1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 - 2021 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* Functions for handling an incoming SMTP call. */
16 /* Initialize for TCP wrappers if so configured. It appears that the macro
17 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
18 including that header, and restore its value afterwards. */
20 #ifdef USE_TCP_WRAPPERS
23 #define EXIM_HAVE_IPV6
29 #define HAVE_IPV6 TRUE
32 int allow_severity = LOG_INFO;
33 int deny_severity = LOG_NOTICE;
34 uschar *tcp_wrappers_name;
38 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
39 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
40 commands that accept arguments, and this in particular applies to AUTH, where
41 the data can be quite long. More recently this value was 2048 in Exim;
42 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
43 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
44 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
45 we need room to handle large base64-encoded AUTHs for GSSAPI.
48 #define SMTP_CMD_BUFFER_SIZE 16384
50 /* Size of buffer for reading SMTP incoming packets */
52 #define IN_BUFFER_SIZE 8192
54 /* Structure for SMTP command list */
61 short int is_mail_cmd;
64 /* Codes for identifying commands. We order them so that those that come first
65 are those for which synchronization is always required. Checking this can help
69 /* These commands are required to be synchronized, i.e. to be the last in a
70 block of commands when pipelining. */
72 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
73 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
74 ETRN_CMD, /* This by analogy with TURN from the RFC */
75 STARTTLS_CMD, /* Required by the STARTTLS RFC */
76 TLS_AUTH_CMD, /* auto-command at start of SSL */
78 /* This is a dummy to identify the non-sync commands when pipelining */
80 NON_SYNC_CMD_PIPELINING,
82 /* These commands need not be synchronized when pipelining */
84 MAIL_CMD, RCPT_CMD, RSET_CMD,
86 /* This is a dummy to identify the non-sync commands when not pipelining */
88 NON_SYNC_CMD_NON_PIPELINING,
90 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
91 processed the message is sent using a series of BDAT commands"
92 implies that BDAT should be synchronized. However, we see Google, at least,
93 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
94 processing of the RCPT response(s). We shall do the same, and not require
95 synch for BDAT. Worse, as the chunk may (very likely will) follow the
96 command-header in the same packet we cannot do the usual "is there any
97 follow-on data after the command line" even for non-pipeline mode.
98 So we'll need an explicit check after reading the expected chunk amount
99 when non-pipe, before sending the ACK. */
103 /* I have been unable to find a statement about the use of pipelining
104 with AUTH, so to be on the safe side it is here, though I kind of feel
105 it should be up there with the synchronized commands. */
109 /* I'm not sure about these, but I don't think they matter. */
114 PROXY_FAIL_IGNORE_CMD,
117 /* These are specials that don't correspond to actual commands */
119 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
120 TOO_MANY_NONMAIL_CMD };
123 /* This is a convenience macro for adding the identity of an SMTP command
124 to the circular buffer that holds a list of the last n received. */
127 smtp_connection_had[smtp_ch_index++] = n; \
128 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
131 /*************************************************
132 * Local static variables *
133 *************************************************/
136 BOOL auth_advertised :1;
138 BOOL tls_advertised :1;
140 BOOL dsn_advertised :1;
142 BOOL helo_verify_required :1;
145 BOOL helo_accept_junk :1;
146 #ifndef DISABLE_PIPE_CONNECT
147 BOOL pipe_connect_acceptable :1;
149 BOOL rcpt_smtp_response_same :1;
150 BOOL rcpt_in_progress :1;
151 BOOL smtp_exit_function_called :1;
153 BOOL smtputf8_advertised :1;
156 .helo_verify_required = FALSE,
157 .helo_verify = FALSE,
158 .smtp_exit_function_called = FALSE,
161 static auth_instance *authenticated_by;
162 static int count_nonmail;
163 static int nonmail_command_count;
164 static int synprot_error_count;
165 static int unknown_command_count;
166 static int sync_cmd_limit;
167 static int smtp_write_error = 0;
169 static uschar *rcpt_smtp_response;
170 static uschar *smtp_data_buffer;
171 static uschar *smtp_cmd_data;
173 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
174 final fields of all except AUTH are forced TRUE at the start of a new message
175 setup, to allow one of each between messages that is not counted as a nonmail
176 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
177 allow a new EHLO after starting up TLS.
179 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
180 counted. However, the flag is changed when AUTH is received, so that multiple
181 failing AUTHs will eventually hit the limit. After a successful AUTH, another
182 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
183 forced TRUE, to allow for the re-authentication that can happen at that point.
185 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
186 count of non-mail commands and possibly provoke an error.
188 tls_auth is a pseudo-command, never expected in input. It is activated
189 on TLS startup and looks for a tls authenticator. */
191 static smtp_cmd_list cmd_list[] = {
192 /* name len cmd has_arg is_mail_cmd */
194 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
195 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
196 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
197 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
199 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
200 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
203 /* If you change anything above here, also fix the definitions below. */
205 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
206 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
207 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
208 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
209 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
210 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
211 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
212 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
213 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
214 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
217 static smtp_cmd_list *cmd_list_end =
218 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
220 #define CMD_LIST_RSET 0
221 #define CMD_LIST_HELO 1
222 #define CMD_LIST_EHLO 2
223 #define CMD_LIST_AUTH 3
224 #define CMD_LIST_STARTTLS 4
225 #define CMD_LIST_TLS_AUTH 5
227 /* This list of names is used for performing the smtp_no_mail logging action.
228 It must be kept in step with the SCH_xxx enumerations. */
230 uschar * smtp_names[] =
232 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
233 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
234 US"STARTTLS", US"VRFY" };
236 static uschar *protocols_local[] = {
237 US"local-smtp", /* HELO */
238 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
239 US"local-esmtp", /* EHLO */
240 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
241 US"local-esmtpa", /* EHLO->AUTH */
242 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
244 static uschar *protocols[] = {
246 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
247 US"esmtp", /* EHLO */
248 US"esmtps", /* EHLO->STARTTLS->EHLO */
249 US"esmtpa", /* EHLO->AUTH */
250 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
255 #define pcrpted 1 /* added to pextend or pnormal */
256 #define pauthed 2 /* added to pextend */
258 /* Sanity check and validate optional args to MAIL FROM: envelope */
261 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
265 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
271 uschar * name; /* option requested during MAIL cmd */
272 int value; /* enum type */
273 BOOL need_value; /* TRUE requires value (name=value pair format)
274 FALSE is a singleton */
276 static env_mail_type_t env_mail_type_list[] = {
277 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
278 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
279 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
281 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
283 { US"RET", ENV_MAIL_OPT_RET, TRUE },
284 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
286 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
288 /* keep this the last entry */
289 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
292 /* When reading SMTP from a remote host, we have to use our own versions of the
293 C input-reading functions, in order to be able to flush the SMTP output only
294 when about to read more data from the socket. This is the only way to get
295 optimal performance when the client is using pipelining. Flushing for every
296 command causes a separate packet and reply packet each time; saving all the
297 responses up (when pipelining) combines them into one packet and one response.
299 For simplicity, these functions are used for *all* SMTP input, not only when
300 receiving over a socket. However, after setting up a secure socket (SSL), input
301 is read via the OpenSSL library, and another set of functions is used instead
304 These functions are set in the receive_getc etc. variables and called with the
305 same interface as the C functions. However, since there can only ever be
306 one incoming SMTP call, we just use a single buffer and flags. There is no need
307 to implement a complicated private FILE-like structure.*/
309 static uschar *smtp_inbuffer;
310 static uschar *smtp_inptr;
311 static uschar *smtp_inend;
312 static int smtp_had_eof;
313 static int smtp_had_error;
316 /* forward declarations */
317 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
318 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
319 static void smtp_quit_handler(uschar **, uschar **);
320 static void smtp_rset_handler(void);
322 /*************************************************
323 * Log incomplete transactions *
324 *************************************************/
326 /* This function is called after a transaction has been aborted by RSET, QUIT,
327 connection drops or other errors. It logs the envelope information received
328 so far in order to preserve address verification attempts.
330 Argument: string to indicate what aborted the transaction
335 incomplete_transaction_log(uschar *what)
337 if (!sender_address /* No transaction in progress */
338 || !LOGGING(smtp_incomplete_transaction))
341 /* Build list of recipients for logging */
343 if (recipients_count > 0)
345 raw_recipients = store_get(recipients_count * sizeof(uschar *), FALSE);
346 for (int i = 0; i < recipients_count; i++)
347 raw_recipients[i] = recipients_list[i].address;
348 raw_recipients_count = recipients_count;
351 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
352 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
359 smtp_command_timeout_exit(void)
361 log_write(L_lost_incoming_connection,
362 LOG_MAIN, "SMTP command timeout on%s connection from %s",
363 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
364 if (smtp_batched_input)
365 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
366 smtp_notquit_exit(US"command-timeout", US"421",
367 US"%s: SMTP command timeout - closing connection",
368 smtp_active_hostname);
369 exim_exit(EXIT_FAILURE);
373 smtp_command_sigterm_exit(void)
375 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
376 if (smtp_batched_input)
377 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
378 smtp_notquit_exit(US"signal-exit", US"421",
379 US"%s: Service not available - closing connection", smtp_active_hostname);
380 exim_exit(EXIT_FAILURE);
384 smtp_data_timeout_exit(void)
386 log_write(L_lost_incoming_connection,
387 LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
388 sender_fullhost ? sender_fullhost : US"local process", sender_address);
389 receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
390 /* Does not return */
394 smtp_data_sigint_exit(void)
396 log_write(0, LOG_MAIN, "%s closed after %s",
397 smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
398 receive_bomb_out(US"signal-exit",
399 US"Service not available - SIGTERM or SIGINT received");
400 /* Does not return */
404 /******************************************************************************/
405 /* SMTP input buffer handling. Most of these are similar to stdio routines. */
410 /* Set up the buffer for inputting using direct read() calls, and arrange to
411 call the local functions instead of the standard C ones. Place a NUL at the
412 end of the buffer to safety-stop C-string reads from it. */
414 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
415 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
416 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
418 smtp_inptr = smtp_inend = smtp_inbuffer;
419 smtp_had_eof = smtp_had_error = 0;
424 /* Refill the buffer, and notify DKIM verification code.
425 Return false for error or EOF.
429 smtp_refill(unsigned lim)
433 if (!smtp_out) return FALSE;
435 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
437 /* Limit amount read, so non-message data is not fed to DKIM.
438 Take care to not touch the safety NUL at the end of the buffer. */
440 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
442 if (smtp_receive_timeout > 0) ALARM_CLR(0);
445 /* Must put the error text in fixed store, because this might be during
446 header reading, where it releases unused store above the header. */
449 if (had_command_timeout) /* set by signal handler */
450 smtp_command_timeout_exit(); /* does not return */
451 if (had_command_sigterm)
452 smtp_command_sigterm_exit();
453 if (had_data_timeout)
454 smtp_data_timeout_exit();
456 smtp_data_sigint_exit();
458 smtp_had_error = save_errno;
459 smtp_read_error = string_copy_perm(
460 string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
467 dkim_exim_verify_feed(smtp_inbuffer, rc);
469 smtp_inend = smtp_inbuffer + rc;
470 smtp_inptr = smtp_inbuffer;
475 /* Check if there is buffered data */
480 return smtp_inptr < smtp_inend;
483 /* SMTP version of getc()
485 This gets the next byte from the SMTP input buffer. If the buffer is empty,
486 it flushes the output, and refills the buffer, with a timeout. The signal
487 handler is set appropriately by the calling function. This function is not used
488 after a connection has negotiated itself into an TLS/SSL state.
490 Arguments: lim Maximum amount to read/buffer
491 Returns: the next character or EOF
495 smtp_getc(unsigned lim)
497 if (!smtp_hasc() && !smtp_refill(lim)) return EOF;
498 return *smtp_inptr++;
501 /* Get many bytes, refilling buffer if needed */
504 smtp_getbuf(unsigned * len)
509 if (!smtp_hasc() && !smtp_refill(*len))
510 { *len = 0; return NULL; }
512 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
519 /* Copy buffered data to the dkim feed.
520 Called, unless TLS, just before starting to read message headers. */
523 smtp_get_cache(unsigned lim)
526 int n = smtp_inend - smtp_inptr;
530 dkim_exim_verify_feed(smtp_inptr, n);
535 /* SMTP version of ungetc()
536 Puts a character back in the input buffer. Only ever called once.
541 Returns: the character
547 if (smtp_inptr <= smtp_inbuffer) /* NB: NOT smtp_hasc() ! */
548 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in smtp_ungetc");
555 /* SMTP version of feof()
556 Tests for a previous EOF
559 Returns: non-zero if the eof flag is set
569 /* SMTP version of ferror()
570 Tests for a previous read error, and returns with errno
571 restored to what it was when the error was detected.
574 Returns: non-zero if the error flag is set
580 errno = smtp_had_error;
581 return smtp_had_error;
585 /* Check if a getc will block or not */
588 smtp_could_getc(void)
592 struct timeval tzero = {.tv_sec = 0, .tv_usec = 0};
594 if (smtp_inptr < smtp_inend)
597 fd = fileno(smtp_in);
600 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
602 if (rc <= 0) return FALSE; /* Not ready to read */
603 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
604 if (rc < 0) return FALSE; /* End of file or error */
611 /******************************************************************************/
612 /*************************************************
613 * Recheck synchronization *
614 *************************************************/
616 /* Synchronization checks can never be perfect because a packet may be on its
617 way but not arrived when the check is done. Normally, the checks happen when
618 commands are read: Exim ensures that there is no more input in the input buffer.
619 In normal cases, the response to the command will be fast, and there is no
622 However, for some commands an ACL is run, and that can include delays. In those
623 cases, it is useful to do another check on the input just before sending the
624 response. This also applies at the start of a connection. This function does
625 that check by means of the select() function, as long as the facility is not
626 disabled or inappropriate. A failure of select() is ignored.
628 When there is unwanted input, we read it so that it appears in the log of the
632 Returns: TRUE if all is well; FALSE if there is input pending
636 wouldblock_reading(void)
639 if (tls_in.active.sock >= 0)
640 return !tls_could_getc();
643 return !smtp_could_getc();
649 if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
652 return wouldblock_reading();
656 /******************************************************************************/
657 /* Variants of the smtp_* input handling functions for use in CHUNKING mode */
659 /* Forward declarations */
660 static inline void bdat_push_receive_functions(void);
661 static inline void bdat_pop_receive_functions(void);
664 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
665 previous BDAT chunk and getting new ones when we run out. Uses the
666 underlying smtp_getc or tls_getc both for that and for getting the
667 (buffered) data byte. EOD signals (an expected) no further data.
668 ERR signals a protocol error, and EOF a closed input stream.
670 Called from read_bdat_smtp() in receive.c for the message body, but also
671 by the headers read loop in receive_msg(); manipulates chunking_state
672 to handle the BDAT command/response.
673 Placed here due to the correlation with the above smtp_getc(), which it wraps,
674 and also by the need to do smtp command/response handling.
676 Arguments: lim (ignored)
677 Returns: the next character or ERR, EOD or EOF
681 bdat_getc(unsigned lim)
683 uschar * user_msg = NULL;
692 if (chunking_data_left > 0)
693 return lwr_receive_getc(chunking_data_left--);
695 bdat_pop_receive_functions();
697 dkim_save = dkim_collect_input;
698 dkim_collect_input = 0;
701 /* Unless PIPELINING was offered, there should be no next command
702 until after we ack that chunk */
704 if (!f.smtp_in_pipelining_advertised && !check_sync())
706 unsigned n = smtp_inend - smtp_inptr;
709 incomplete_transaction_log(US"sync failure");
710 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
711 "(next input sent too soon: pipelining was not advertised): "
712 "rejected \"%s\" %s next input=\"%s\"%s",
713 smtp_cmd_buffer, host_and_ident(TRUE),
714 string_printing(string_copyn(smtp_inptr, n)),
715 smtp_inend - smtp_inptr > n ? "..." : "");
716 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
717 US"SMTP synchronization error");
718 goto repeat_until_rset;
721 /* If not the last, ack the received chunk. The last response is delayed
722 until after the data ACL decides on it */
724 if (chunking_state == CHUNKING_LAST)
727 dkim_collect_input = dkim_save;
728 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
729 dkim_collect_input = 0;
734 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
735 chunking_state = CHUNKING_OFFERED;
736 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
738 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
739 QUIT, RSET or NOOP but handling them seems obvious */
742 switch(smtp_read_command(TRUE, 1))
745 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
746 US"only BDAT permissible after non-LAST BDAT");
749 switch(smtp_read_command(TRUE, 1))
751 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
752 case EOF_CMD: return EOF;
753 case RSET_CMD: smtp_rset_handler(); return ERR;
754 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
755 US"only RSET accepted now") > 0)
757 goto repeat_until_rset;
761 smtp_quit_handler(&user_msg, &log_msg);
772 smtp_printf("250 OK\r\n", FALSE);
779 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
781 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
782 US"missing size for BDAT command");
785 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
786 ? CHUNKING_LAST : CHUNKING_ACTIVE;
787 chunking_data_left = chunking_datasize;
788 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
789 (int)chunking_state, chunking_data_left);
791 if (chunking_datasize == 0)
792 if (chunking_state == CHUNKING_LAST)
796 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
797 US"zero size for BDAT command");
798 goto repeat_until_rset;
801 bdat_push_receive_functions();
803 dkim_collect_input = dkim_save;
805 break; /* to top of main loop */
814 if (chunking_data_left > 0)
815 return lwr_receive_hasc();
820 bdat_getbuf(unsigned * len)
824 if (chunking_data_left <= 0)
825 { *len = 0; return NULL; }
827 if (*len > chunking_data_left) *len = chunking_data_left;
828 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
829 chunking_data_left -= *len;
834 bdat_flush_data(void)
836 while (chunking_data_left)
838 unsigned n = chunking_data_left;
839 if (!bdat_getbuf(&n)) break;
842 bdat_pop_receive_functions();
844 if (chunking_state != CHUNKING_LAST)
846 chunking_state = CHUNKING_OFFERED;
847 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
853 bdat_push_receive_functions(void)
855 /* push the current receive_* function on the "stack", and
856 replace them by bdat_getc(), which in turn will use the lwr_receive_*
857 functions to do the dirty work. */
858 if (!lwr_receive_getc)
860 lwr_receive_getc = receive_getc;
861 lwr_receive_getbuf = receive_getbuf;
862 lwr_receive_hasc = receive_hasc;
863 lwr_receive_ungetc = receive_ungetc;
867 DEBUG(D_receive) debug_printf("chunking double-push receive functions\n");
870 receive_getc = bdat_getc;
871 receive_getbuf = bdat_getbuf;
872 receive_hasc = bdat_hasc;
873 receive_ungetc = bdat_ungetc;
877 bdat_pop_receive_functions(void)
879 if (!lwr_receive_getc)
881 DEBUG(D_receive) debug_printf("chunking double-pop receive functions\n");
884 receive_getc = lwr_receive_getc;
885 receive_getbuf = lwr_receive_getbuf;
886 receive_hasc = lwr_receive_hasc;
887 receive_ungetc = lwr_receive_ungetc;
889 lwr_receive_getc = NULL;
890 lwr_receive_getbuf = NULL;
891 lwr_receive_hasc = NULL;
892 lwr_receive_ungetc = NULL;
898 chunking_data_left++;
899 bdat_push_receive_functions(); /* we're not done yet, calling push is safe, because it checks the state before pushing anything */
900 return lwr_receive_ungetc(ch);
905 /******************************************************************************/
907 /*************************************************
908 * Write formatted string to SMTP channel *
909 *************************************************/
911 /* This is a separate function so that we don't have to repeat everything for
912 TLS support or debugging. It is global so that the daemon and the
913 authentication functions can use it. It does not return any error indication,
914 because major problems such as dropped connections won't show up till an output
915 flush for non-TLS connections. The smtp_fflush() function is available for
916 checking that: for convenience, TLS output errors are remembered here so that
917 they are also picked up later by smtp_fflush().
919 This function is exposed to the local_scan API; do not change the signature.
923 more further data expected
924 ... optional arguments
930 smtp_printf(const char *format, BOOL more, ...)
935 smtp_vprintf(format, more, ap);
939 /* This is split off so that verify.c:respond_printf() can, in effect, call
940 smtp_printf(), bearing in mind that in C a vararg function can't directly
941 call another vararg function, only a function which accepts a va_list.
943 This function is exposed to the local_scan API; do not change the signature.
945 /*XXX consider passing caller-info in, for string_vformat-onward */
948 smtp_vprintf(const char *format, BOOL more, va_list ap)
950 gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
953 /* Use taint-unchecked routines for writing into big_buffer, trusting
954 that we'll never expand it. */
956 yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
957 string_from_gstring(&gs);
961 uschar *msg_copy, *cr, *end;
962 msg_copy = string_copy(gs.s);
963 end = msg_copy + gs.ptr;
964 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
965 memmove(cr, cr + 1, (end--) - cr);
966 debug_printf("SMTP>> %s", msg_copy);
971 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
972 smtp_closedown(US"Unexpected error");
973 exim_exit(EXIT_FAILURE);
976 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
977 have had the same. Note: this code is also present in smtp_respond(). It would
978 be tidier to have it only in one place, but when it was added, it was easier to
979 do it that way, so as not to have to mess with the code for the RCPT command,
980 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
982 if (fl.rcpt_in_progress)
984 if (rcpt_smtp_response == NULL)
985 rcpt_smtp_response = string_copy(big_buffer);
986 else if (fl.rcpt_smtp_response_same &&
987 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
988 fl.rcpt_smtp_response_same = FALSE;
989 fl.rcpt_in_progress = FALSE;
992 /* Now write the string */
996 tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
998 (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
1000 smtp_write_error = -1;
1005 /*************************************************
1006 * Flush SMTP out and check for error *
1007 *************************************************/
1009 /* This function isn't currently used within Exim (it detects errors when it
1010 tries to read the next SMTP input), but is available for use in local_scan().
1011 It flushes the output and checks for errors.
1014 Returns: 0 for no error; -1 after an error
1020 if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
1024 tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
1026 (fflush(smtp_out) != 0)
1028 smtp_write_error = -1;
1030 return smtp_write_error;
1035 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
1036 a reponse with the one following. */
1039 pipeline_response(void)
1041 if ( !smtp_enforce_sync || !sender_host_address
1042 || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
1045 if (wouldblock_reading()) return FALSE;
1046 f.smtp_in_pipelining_used = TRUE;
1051 #ifndef DISABLE_PIPE_CONNECT
1053 pipeline_connect_sends(void)
1055 if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
1058 if (wouldblock_reading()) return FALSE;
1059 f.smtp_in_early_pipe_used = TRUE;
1064 /*************************************************
1065 * SMTP command read timeout *
1066 *************************************************/
1068 /* Signal handler for timing out incoming SMTP commands. This attempts to
1071 Argument: signal number (SIGALRM)
1076 command_timeout_handler(int sig)
1078 had_command_timeout = sig;
1083 /*************************************************
1084 * SIGTERM received *
1085 *************************************************/
1087 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
1089 Argument: signal number (SIGTERM)
1094 command_sigterm_handler(int sig)
1096 had_command_sigterm = sig;
1102 #ifdef SUPPORT_PROXY
1103 /*************************************************
1104 * Check if host is required proxy host *
1105 *************************************************/
1106 /* The function determines if inbound host will be a regular smtp host
1107 or if it is configured that it must use Proxy Protocol. A local
1115 check_proxy_protocol_host()
1119 if ( sender_host_address
1120 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
1121 sender_host_address, NULL)) == OK)
1124 debug_printf("Detected proxy protocol configured host\n");
1125 proxy_session = TRUE;
1127 return proxy_session;
1131 /*************************************************
1132 * Read data until newline or end of buffer *
1133 *************************************************/
1134 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1135 read an entire buffer and assume there will be nothing past a proxy protocol
1136 header. Our approach normally is to use stdio, but again that relies upon
1137 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1138 reading _nothing_ before client TLS handshake. So we don't want to use the
1139 usual buffering reads which may read enough to block TLS starting.
1141 So unfortunately we're down to "read one byte at a time, with a syscall each,
1142 and expect a little overhead", for all proxy-opened connections which are v1,
1143 just to handle the TLS-on-connect case. Since SSL functions wrap the
1144 underlying fd, we can't assume that we can feed them any already-read content.
1146 We need to know where to read to, the max capacity, and we'll read until we
1147 get a CR and one more character. Let the caller scream if it's CR+!LF.
1149 Return the amount read.
1153 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1155 uschar *to = base + already;
1161 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1162 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1164 cr = memchr(base, '\r', already);
1167 if ((cr - base) < already - 1)
1169 /* \r and presumed \n already within what we have; probably not
1170 actually proxy protocol, but abort cleanly. */
1173 /* \r is last character read, just need one more. */
1177 while (capacity > 0)
1179 do { ret = read(fd, to, 1); } while (ret == -1 && errno == EINTR && !had_command_timeout);
1191 /* reached end without having room for a final newline, abort */
1196 /*************************************************
1197 * Setup host for proxy protocol *
1198 *************************************************/
1199 /* The function configures the connection based on a header from the
1200 inbound host to use Proxy Protocol. The specification is very exact
1201 so exit with an error if do not find the exact required pieces. This
1202 includes an incorrect number of spaces separating args.
1205 Returns: Boolean success
1209 setup_proxy_protocol_host()
1221 struct { /* TCP/UDP over IPv4, len = 12 */
1227 struct { /* TCP/UDP over IPv6, len = 36 */
1228 uint8_t src_addr[16];
1229 uint8_t dst_addr[16];
1233 struct { /* AF_UNIX sockets, len = 216 */
1234 uschar src_addr[108];
1235 uschar dst_addr[108];
1241 /* Temp variables used in PPv2 address:port parsing */
1243 char tmpip[INET_ADDRSTRLEN];
1244 struct sockaddr_in tmpaddr;
1245 char tmpip6[INET6_ADDRSTRLEN];
1246 struct sockaddr_in6 tmpaddr6;
1248 /* We can't read "all data until end" because while SMTP is
1249 server-speaks-first, the TLS handshake is client-speaks-first, so for
1250 TLS-on-connect ports the proxy protocol header will usually be immediately
1251 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1252 reinject data for reading by those. So instead we first read "enough to be
1253 safely read within the header, and figure out how much more to read".
1254 For v1 we will later read to the end-of-line, for v2 we will read based upon
1257 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1258 data is needed total. For v1, where the line looks like:
1259 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1261 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1262 We seem to support that. So, if we read 14 octets then we can tell if we're
1263 v2 or v1. If we're v1, we can continue reading as normal.
1265 If we're v2, we can't slurp up the entire header. We need the length in the
1266 15th & 16th octets, then to read everything after that.
1268 So to safely handle v1 and v2, with client-sent-first supported correctly,
1269 we have to do a minimum of 3 read calls, not 1. Eww.
1272 #define PROXY_INITIAL_READ 14
1273 #define PROXY_V2_HEADER_SIZE 16
1274 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1275 # error Code bug in sizes of data to read for proxy usage
1280 int fd = fileno(smtp_in);
1281 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1282 uschar * iptype; /* To display debug info */
1283 socklen_t vslen = sizeof(struct timeval);
1286 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1287 ALARM(proxy_protocol_timeout);
1291 /* The inbound host was declared to be a Proxy Protocol host, so
1292 don't do a PEEK into the data, actually slurp up enough to be
1293 "safe". Can't take it all because TLS-on-connect clients follow
1294 immediately with TLS handshake. */
1295 ret = read(fd, &hdr, PROXY_INITIAL_READ);
1297 while (ret == -1 && errno == EINTR && !had_command_timeout);
1302 /* For v2, handle reading the length, and then the rest. */
1303 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1308 /* First get the length fields. */
1311 retmore = read(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ);
1312 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1317 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1319 /* May 2014: haproxy combined the version and command into one byte to
1320 allow two full bytes for the length field in order to proxy SSL
1321 connections. SSL Proxy is not supported in this version of Exim, but
1322 must still separate values here. */
1326 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1330 /* The v2 header will always be 16 bytes per the spec. */
1331 size = 16 + ntohs(hdr.v2.len);
1332 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1333 size, (int)sizeof(hdr));
1335 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1336 amount that we need. Double-check that the size is not unreasonable, then
1338 if (size > sizeof(hdr))
1340 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1348 retmore = read(fd, (uschar*)&hdr + ret, size-ret);
1349 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1353 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1354 } while (ret < size);
1356 } /* end scope for getting rest of data for v2 */
1358 /* At this point: if PROXYv2, we've read the exact size required for all data;
1359 if PROXYv1 then we've read "less than required for any valid line" and should
1362 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1364 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1368 case 0x01: /* PROXY command */
1371 case 0x11: /* TCPv4 address type */
1373 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1374 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1375 if (!string_is_ip_address(US tmpip, NULL))
1377 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1380 proxy_local_address = sender_host_address;
1381 sender_host_address = string_copy(US tmpip);
1382 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1383 proxy_local_port = sender_host_port;
1384 sender_host_port = tmpport;
1385 /* Save dest ip/port */
1386 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1387 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1388 if (!string_is_ip_address(US tmpip, NULL))
1390 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1393 proxy_external_address = string_copy(US tmpip);
1394 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1395 proxy_external_port = tmpport;
1397 case 0x21: /* TCPv6 address type */
1399 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1400 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1401 if (!string_is_ip_address(US tmpip6, NULL))
1403 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1406 proxy_local_address = sender_host_address;
1407 sender_host_address = string_copy(US tmpip6);
1408 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1409 proxy_local_port = sender_host_port;
1410 sender_host_port = tmpport;
1411 /* Save dest ip/port */
1412 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1413 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1414 if (!string_is_ip_address(US tmpip6, NULL))
1416 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1419 proxy_external_address = string_copy(US tmpip6);
1420 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1421 proxy_external_port = tmpport;
1425 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1429 /* Unsupported protocol, keep local connection address */
1431 case 0x00: /* LOCAL command */
1432 /* Keep local connection address for LOCAL */
1437 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1441 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1445 uschar *sp; /* Utility variables follow */
1450 /* get the rest of the line */
1451 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1456 p = string_copy(hdr.v1.line);
1457 end = memchr(p, '\r', ret - 1);
1459 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1461 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1464 *end = '\0'; /* Terminate the string */
1465 size = end + 2 - p; /* Skip header + CRLF */
1466 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1467 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1468 /* Step through the string looking for the required fields. Ensure
1469 strict adherence to required formatting, exit for any error. */
1471 if (!isspace(*(p++)))
1473 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1476 if (!Ustrncmp(p, CCS"TCP4", 4))
1478 else if (!Ustrncmp(p,CCS"TCP6", 4))
1480 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1482 iptype = US"Unknown";
1487 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1491 p += Ustrlen(iptype);
1492 if (!isspace(*(p++)))
1494 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1497 /* Find the end of the arg */
1498 if ((sp = Ustrchr(p, ' ')) == NULL)
1501 debug_printf("Did not find proxied src %s\n", iptype);
1505 if(!string_is_ip_address(p, NULL))
1508 debug_printf("Proxied src arg is not an %s address\n", iptype);
1511 proxy_local_address = sender_host_address;
1512 sender_host_address = p;
1514 if ((sp = Ustrchr(p, ' ')) == NULL)
1517 debug_printf("Did not find proxy dest %s\n", iptype);
1521 if(!string_is_ip_address(p, NULL))
1524 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1527 proxy_external_address = p;
1529 if ((sp = Ustrchr(p, ' ')) == NULL)
1531 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1535 tmp_port = strtol(CCS p, &endc, 10);
1536 if (*endc || tmp_port == 0)
1539 debug_printf("Proxied src port '%s' not an integer\n", p);
1542 proxy_local_port = sender_host_port;
1543 sender_host_port = tmp_port;
1545 if ((sp = Ustrchr(p, '\0')) == NULL)
1547 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1550 tmp_port = strtol(CCS p, &endc, 10);
1551 if (*endc || tmp_port == 0)
1554 debug_printf("Proxy dest port '%s' not an integer\n", p);
1557 proxy_external_port = tmp_port;
1558 /* Already checked for /r /n above. Good V1 header received. */
1562 /* Wrong protocol */
1563 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1564 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1570 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1571 yield = proxy_session;
1573 /* Don't flush any potential buffer contents. Any input on proxyfail
1574 should cause a synchronization failure */
1577 DEBUG(D_receive) if (had_command_timeout)
1578 debug_printf("Timeout while reading proxy header\n");
1583 sender_host_name = NULL;
1584 (void) host_name_lookup();
1585 host_build_sender_fullhost();
1589 f.proxy_session_failed = TRUE;
1591 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1599 /*************************************************
1600 * Read one command line *
1601 *************************************************/
1603 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1604 There are sites that don't do this, and in any case internal SMTP probably
1605 should check only for LF. Consequently, we check here for LF only. The line
1606 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1607 an unknown command. The command is read into the global smtp_cmd_buffer so that
1608 it is available via $smtp_command.
1610 The character reading routine sets up a timeout for each block actually read
1611 from the input (which may contain more than one command). We set up a special
1612 signal handler that closes down the session on a timeout. Control does not
1613 return when it runs.
1616 check_sync if TRUE, check synchronization rules if global option is TRUE
1617 buffer_lim maximum to buffer in lower layer
1619 Returns: a code identifying the command (enumerated above)
1623 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1627 BOOL hadnull = FALSE;
1629 had_command_timeout = 0;
1630 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1632 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1634 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1636 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1644 smtp_cmd_buffer[ptr++] = c;
1647 receive_linecount++; /* For BSMTP errors */
1648 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1650 /* If hit end of file, return pseudo EOF command. Whether we have a
1651 part-line already read doesn't matter, since this is an error state. */
1653 if (c == EOF) return EOF_CMD;
1655 /* Remove any CR and white space at the end of the line, and terminate the
1658 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1659 smtp_cmd_buffer[ptr] = 0;
1661 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1663 /* NULLs are not allowed in SMTP commands */
1665 if (hadnull) return BADCHAR_CMD;
1667 /* Scan command list and return identity, having set the data pointer
1668 to the start of the actual data characters. Check for SMTP synchronization
1671 for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
1673 #ifdef SUPPORT_PROXY
1674 /* Only allow QUIT command if Proxy Protocol parsing failed */
1675 if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
1679 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1680 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1681 || smtp_cmd_buffer[p->len] == 0
1682 || smtp_cmd_buffer[p->len] == ' '
1685 if ( smtp_inptr < smtp_inend /* Outstanding input */
1686 && p->cmd < sync_cmd_limit /* Command should sync */
1687 && check_sync /* Local flag set */
1688 && smtp_enforce_sync /* Global flag set */
1689 && sender_host_address != NULL /* Not local input */
1690 && !f.sender_host_notsocket /* Really is a socket */
1694 /* The variables $smtp_command and $smtp_command_argument point into the
1695 unmodified input buffer. A copy of the latter is taken for actual
1696 processing, so that it can be chopped up into separate parts if necessary,
1697 for example, when processing a MAIL command options such as SIZE that can
1698 follow the sender address. */
1700 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1701 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1702 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1703 smtp_cmd_data = smtp_data_buffer;
1705 /* Count non-mail commands from those hosts that are controlled in this
1706 way. The default is all hosts. We don't waste effort checking the list
1707 until we get a non-mail command, but then cache the result to save checking
1708 again. If there's a DEFER while checking the host, assume it's in the list.
1710 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1711 start of each incoming message by fiddling with the value in the table. */
1713 if (!p->is_mail_cmd)
1715 if (count_nonmail == TRUE_UNSET) count_nonmail =
1716 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1717 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1718 return TOO_MANY_NONMAIL_CMD;
1721 /* If there is data for a command that does not expect it, generate the
1724 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1728 #ifdef SUPPORT_PROXY
1729 /* Only allow QUIT command if Proxy Protocol parsing failed */
1730 if (proxy_session && f.proxy_session_failed)
1731 return PROXY_FAIL_IGNORE_CMD;
1734 /* Enforce synchronization for unknown commands */
1736 if ( smtp_inptr < smtp_inend /* Outstanding input */
1737 && check_sync /* Local flag set */
1738 && smtp_enforce_sync /* Global flag set */
1739 && sender_host_address /* Not local input */
1740 && !f.sender_host_notsocket /* Really is a socket */
1749 /*************************************************
1750 * Forced closedown of call *
1751 *************************************************/
1753 /* This function is called from log.c when Exim is dying because of a serious
1754 disaster, and also from some other places. If an incoming non-batched SMTP
1755 channel is open, it swallows the rest of the incoming message if in the DATA
1756 phase, sends the reply string, and gives an error to all subsequent commands
1757 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1761 message SMTP reply string to send, excluding the code
1767 smtp_closedown(uschar *message)
1769 if (!smtp_in || smtp_batched_input) return;
1770 receive_swallow_smtp();
1771 smtp_printf("421 %s\r\n", FALSE, message);
1773 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1779 f.smtp_in_quit = TRUE;
1780 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1785 smtp_printf("250 Reset OK\r\n", FALSE);
1789 smtp_printf("421 %s\r\n", FALSE, message);
1797 /*************************************************
1798 * Set up connection info for logging *
1799 *************************************************/
1801 /* This function is called when logging information about an SMTP connection.
1802 It sets up appropriate source information, depending on the type of connection.
1803 If sender_fullhost is NULL, we are at a very early stage of the connection;
1804 just use the IP address.
1807 Returns: a string describing the connection
1811 smtp_get_connection_info(void)
1813 const uschar * hostname = sender_fullhost
1814 ? sender_fullhost : sender_host_address;
1817 return string_sprintf("SMTP connection from %s", hostname);
1819 if (f.sender_host_unknown || f.sender_host_notsocket)
1820 return string_sprintf("SMTP connection from %s", sender_ident);
1823 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1825 if (LOGGING(incoming_interface) && interface_address)
1826 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1827 interface_address, interface_port);
1829 return string_sprintf("SMTP connection from %s", hostname);
1835 /* Append TLS-related information to a log line
1838 g String under construction: allocated string to extend, or NULL
1840 Returns: Allocated string or NULL
1843 s_tlslog(gstring * g)
1845 if (LOGGING(tls_cipher) && tls_in.cipher)
1847 g = string_append(g, 2, US" X=", tls_in.cipher);
1848 #ifndef DISABLE_TLS_RESUME
1849 if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
1850 g = string_catn(g, US"*", 1);
1853 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1854 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1855 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1856 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1857 if (LOGGING(tls_sni) && tls_in.sni)
1858 g = string_append(g, 2, US" SNI=", string_printing2(tls_in.sni, SP_TAB|SP_SPACE));
1866 s_connhad_log(gstring * g)
1868 const uschar * sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE
1869 ? US" C=..." : US" C=";
1871 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1872 if (smtp_connection_had[i] != SCH_NONE)
1874 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1877 for (int i = 0; i < smtp_ch_index; i++, sep = US",")
1878 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1883 /*************************************************
1884 * Log lack of MAIL if so configured *
1885 *************************************************/
1887 /* This function is called when an SMTP session ends. If the log selector
1888 smtp_no_mail is set, write a log line giving some details of what has happened
1889 in the SMTP session.
1896 smtp_log_no_mail(void)
1901 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1904 if (sender_host_authenticated)
1906 g = string_append(g, 2, US" A=", sender_host_authenticated);
1907 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1914 g = s_connhad_log(g);
1916 if (!(s = string_from_gstring(g))) s = US"";
1918 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1919 f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
1920 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1924 /* Return list of recent smtp commands */
1929 gstring * list = NULL;
1932 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1933 if (smtp_connection_had[i] != SCH_NONE)
1934 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1936 for (int i = 0; i < smtp_ch_index; i++)
1937 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1939 s = string_from_gstring(list);
1940 return s ? s : US"";
1946 /*************************************************
1947 * Check HELO line and set sender_helo_name *
1948 *************************************************/
1950 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1951 the domain name of the sending host, or an ip literal in square brackets. The
1952 argument is placed in sender_helo_name, which is in malloc store, because it
1953 must persist over multiple incoming messages. If helo_accept_junk is set, this
1954 host is permitted to send any old junk (needed for some broken hosts).
1955 Otherwise, helo_allow_chars can be used for rogue characters in general
1956 (typically people want to let in underscores).
1959 s the data portion of the line (already past any white space)
1961 Returns: TRUE or FALSE
1965 check_helo(uschar *s)
1968 uschar *end = s + Ustrlen(s);
1969 BOOL yield = fl.helo_accept_junk;
1971 /* Discard any previous helo name */
1973 sender_helo_name = NULL;
1975 /* Skip tests if junk is permitted. */
1979 /* Allow the new standard form for IPv6 address literals, namely,
1980 [IPv6:....], and because someone is bound to use it, allow an equivalent
1981 IPv4 form. Allow plain addresses as well. */
1988 if (strncmpic(s, US"[IPv6:", 6) == 0)
1989 yield = (string_is_ip_address(s+6, NULL) == 6);
1990 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1991 yield = (string_is_ip_address(s+6, NULL) == 4);
1993 yield = (string_is_ip_address(s+1, NULL) != 0);
1998 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1999 that have been configured (usually underscore - sigh). */
2002 for (yield = TRUE; *s; s++)
2003 if (!isalnum(*s) && *s != '.' && *s != '-' &&
2004 Ustrchr(helo_allow_chars, *s) == NULL)
2010 /* Save argument if OK */
2012 if (yield) sender_helo_name = string_copy_perm(start, TRUE);
2020 /*************************************************
2021 * Extract SMTP command option *
2022 *************************************************/
2024 /* This function picks the next option setting off the end of smtp_cmd_data. It
2025 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
2026 things that can appear there.
2029 name point this at the name
2030 value point this at the data string
2032 Returns: TRUE if found an option
2036 extract_option(uschar **name, uschar **value)
2040 if (Ustrlen(smtp_cmd_data) <= 0) return FALSE;
2041 v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
2042 while (v > smtp_cmd_data && isspace(*v)) v--;
2045 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
2047 /* Take care to not stop at a space embedded in a quoted local-part */
2050 do v--; while (v > smtp_cmd_data && *v != '"');
2051 if (v <= smtp_cmd_data) return FALSE;
2055 if (v <= smtp_cmd_data) return FALSE;
2060 while (n > smtp_cmd_data && isalpha(n[-1])) n--;
2061 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
2062 if (n <= smtp_cmd_data || !isspace(n[-1])) return FALSE;
2079 /*************************************************
2080 * Reset for new message *
2081 *************************************************/
2083 /* This function is called whenever the SMTP session is reset from
2084 within either of the setup functions; also from the daemon loop.
2086 Argument: the stacking pool storage reset point
2091 smtp_reset(void *reset_point)
2093 recipients_list = NULL;
2094 rcpt_count = rcpt_defer_count = rcpt_fail_count =
2095 raw_recipients_count = recipients_count = recipients_list_max = 0;
2096 message_linecount = 0;
2098 message_body = message_body_end = NULL;
2099 acl_added_headers = NULL;
2100 acl_removed_headers = NULL;
2101 f.queue_only_policy = FALSE;
2102 rcpt_smtp_response = NULL;
2103 fl.rcpt_smtp_response_same = TRUE;
2104 fl.rcpt_in_progress = FALSE;
2105 f.deliver_freeze = FALSE; /* Can be set by ACL */
2106 freeze_tell = freeze_tell_config; /* Can be set by ACL */
2107 fake_response = OK; /* Can be set by ACL */
2108 #ifdef WITH_CONTENT_SCAN
2109 f.no_mbox_unspool = FALSE; /* Can be set by ACL */
2111 f.submission_mode = FALSE; /* Can be set by ACL */
2112 f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
2113 f.active_local_from_check = local_from_check; /* Can be set by ACL */
2114 f.active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
2115 sending_ip_address = NULL;
2116 return_path = sender_address = NULL;
2117 deliver_localpart_data = deliver_domain_data =
2118 recipient_data = sender_data = NULL; /* Can be set by ACL */
2119 recipient_verify_failure = NULL;
2120 deliver_localpart_parent = deliver_localpart_orig = NULL;
2121 deliver_domain_parent = deliver_domain_orig = NULL;
2122 callout_address = NULL;
2123 submission_name = NULL; /* Can be set by ACL */
2124 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
2125 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
2126 sender_verified_list = NULL; /* No senders verified */
2127 memset(sender_address_cache, 0, sizeof(sender_address_cache));
2128 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
2130 authenticated_sender = NULL;
2131 #ifdef EXPERIMENTAL_BRIGHTMAIL
2133 bmi_verdicts = NULL;
2135 dnslist_domain = dnslist_matched = NULL;
2137 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2138 spf_result_guessed = FALSE;
2140 #ifndef DISABLE_DKIM
2141 dkim_cur_signer = dkim_signers =
2142 dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
2143 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2144 f.dkim_disable_verify = FALSE;
2145 dkim_collect_input = 0;
2146 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2147 dkim_key_length = 0;
2149 #ifdef SUPPORT_DMARC
2150 f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
2151 dmarc_domain_policy = dmarc_status = dmarc_status_text =
2152 dmarc_used_domain = NULL;
2154 #ifdef EXPERIMENTAL_ARC
2155 arc_state = arc_state_reason = NULL;
2156 arc_received_instance = 0;
2160 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2161 #ifndef DISABLE_PRDR
2162 prdr_requested = FALSE;
2165 message_smtputf8 = FALSE;
2167 body_linecount = body_zerocount = 0;
2169 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2170 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2171 /* Note that ratelimiters_conn persists across resets. */
2173 /* Reset message ACL variables */
2177 /* Warning log messages are saved in malloc store. They are saved to avoid
2178 repetition in the same message, but it seems right to repeat them for different
2181 while (acl_warn_logged)
2183 string_item *this = acl_warn_logged;
2184 acl_warn_logged = acl_warn_logged->next;
2189 store_reset(reset_point);
2192 return store_mark();
2199 /*************************************************
2200 * Initialize for incoming batched SMTP message *
2201 *************************************************/
2203 /* This function is called from smtp_setup_msg() in the case when
2204 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2205 of messages in one file with SMTP commands between them. All errors must be
2206 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2207 relevant. After an error on a sender, or an invalid recipient, the remainder
2208 of the message is skipped. The value of received_protocol is already set.
2211 Returns: > 0 message successfully started (reached DATA)
2212 = 0 QUIT read or end of file reached
2213 < 0 should not occur
2217 smtp_setup_batch_msg(void)
2220 rmark reset_point = store_mark();
2222 /* Save the line count at the start of each transaction - single commands
2223 like HELO and RSET count as whole transactions. */
2225 bsmtp_transaction_linecount = receive_linecount;
2227 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2229 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2230 reset_point = smtp_reset(reset_point); /* Reset for start of message */
2232 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2233 value. The values are 2 larger than the required yield of the function. */
2238 uschar *recipient = NULL;
2239 int start, end, sender_domain, recipient_domain;
2241 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2243 /* The HELO/EHLO commands set sender_address_helo if they have
2244 valid data; otherwise they are ignored, except that they do
2245 a reset of the state. */
2250 check_helo(smtp_cmd_data);
2254 cancel_cutthrough_connection(TRUE, US"RSET received");
2255 reset_point = smtp_reset(reset_point);
2256 bsmtp_transaction_linecount = receive_linecount;
2260 /* The MAIL FROM command requires an address as an operand. All we
2261 do here is to parse it for syntactic correctness. The form "<>" is
2262 a special case which converts into an empty string. The start/end
2263 pointers in the original are not used further for this address, as
2264 it is the canonical extracted address which is all that is kept. */
2267 smtp_mailcmd_count++; /* Count for no-mail log */
2269 /* The function moan_smtp_batch() does not return. */
2270 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2272 if (smtp_cmd_data[0] == 0)
2273 /* The function moan_smtp_batch() does not return. */
2274 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2276 /* Reset to start of message */
2278 cancel_cutthrough_connection(TRUE, US"MAIL received");
2279 reset_point = smtp_reset(reset_point);
2281 /* Apply SMTP rewrite */
2283 raw_sender = rewrite_existflags & rewrite_smtp
2284 /* deconst ok as smtp_cmd_data was not const */
2285 ? US rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL,
2286 FALSE, US"", global_rewrite_rules)
2289 /* Extract the address; the TRUE flag allows <> as valid */
2292 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2296 /* The function moan_smtp_batch() does not return. */
2297 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2299 sender_address = string_copy(raw_sender);
2301 /* Qualify unqualified sender addresses if permitted to do so. */
2304 && sender_address[0] != 0 && sender_address[0] != '@')
2305 if (f.allow_unqualified_sender)
2307 /* deconst ok as sender_address was not const */
2308 sender_address = US rewrite_address_qualify(sender_address, FALSE);
2309 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2310 "and rewritten\n", raw_sender);
2312 /* The function moan_smtp_batch() does not return. */
2314 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2319 /* The RCPT TO command requires an address as an operand. All we do
2320 here is to parse it for syntactic correctness. There may be any number
2321 of RCPT TO commands, specifying multiple senders. We build them all into
2322 a data structure that is in argc/argv format. The start/end values
2323 given by parse_extract_address are not used, as we keep only the
2324 extracted address. */
2327 if (!sender_address)
2328 /* The function moan_smtp_batch() does not return. */
2329 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2331 if (smtp_cmd_data[0] == 0)
2332 /* The function moan_smtp_batch() does not return. */
2333 moan_smtp_batch(smtp_cmd_buffer,
2334 "501 RCPT TO must have an address operand");
2336 /* Check maximum number allowed */
2338 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2339 /* The function moan_smtp_batch() does not return. */
2340 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2341 recipients_max_reject? "552": "452");
2343 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2344 recipient address */
2346 recipient = rewrite_existflags & rewrite_smtp
2347 /* deconst ok as smtp_cmd_data was not const */
2348 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2349 global_rewrite_rules)
2352 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2353 &recipient_domain, FALSE);
2356 /* The function moan_smtp_batch() does not return. */
2357 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2359 /* If the recipient address is unqualified, qualify it if permitted. Then
2360 add it to the list of recipients. */
2362 if (!recipient_domain)
2363 if (f.allow_unqualified_recipient)
2365 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2367 /* deconst ok as recipient was not const */
2368 recipient = US rewrite_address_qualify(recipient, TRUE);
2370 /* The function moan_smtp_batch() does not return. */
2372 moan_smtp_batch(smtp_cmd_buffer,
2373 "501 recipient address must contain a domain");
2375 receive_add_recipient(recipient, -1);
2379 /* The DATA command is legal only if it follows successful MAIL FROM
2380 and RCPT TO commands. This function is complete when a valid DATA
2381 command is encountered. */
2384 if (!sender_address || recipients_count <= 0)
2385 /* The function moan_smtp_batch() does not return. */
2386 if (!sender_address)
2387 moan_smtp_batch(smtp_cmd_buffer,
2388 "503 MAIL FROM:<sender> command must precede DATA");
2390 moan_smtp_batch(smtp_cmd_buffer,
2391 "503 RCPT TO:<recipient> must precede DATA");
2394 done = 3; /* DATA successfully achieved */
2395 message_ended = END_NOTENDED; /* Indicate in middle of message */
2400 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2407 bsmtp_transaction_linecount = receive_linecount;
2412 f.smtp_in_quit = TRUE;
2419 /* The function moan_smtp_batch() does not return. */
2420 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2425 /* The function moan_smtp_batch() does not return. */
2426 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2431 /* The function moan_smtp_batch() does not return. */
2432 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2437 return done - 2; /* Convert yield values */
2445 smtp_log_tls_fail(uschar * errstr)
2447 uschar * conn_info = smtp_get_connection_info();
2449 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2450 /* I'd like to get separated H= here, but too hard for now */
2452 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2466 socklen_t len = sizeof(is_fastopen);
2468 /* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
2469 TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
2471 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
2476 debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
2477 f.tcp_in_fastopen = TRUE;
2480 else DEBUG(D_receive)
2481 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2483 # elif defined(TCP_INFO)
2484 struct tcp_info tinfo;
2485 socklen_t len = sizeof(tinfo);
2487 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
2488 # ifdef TCPI_OPT_SYN_DATA /* FreeBSD 11,12 do not seem to have this yet */
2489 if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
2492 debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
2493 f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
2497 if (tinfo.tcpi_state == TCP_SYN_RECV) /* Not seen on FreeBSD 12.1 */
2500 debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
2501 f.tcp_in_fastopen = TRUE;
2503 else DEBUG(D_receive)
2504 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2510 /*************************************************
2511 * Start an SMTP session *
2512 *************************************************/
2514 /* This function is called at the start of an SMTP session. Thereafter,
2515 smtp_setup_msg() is called to initiate each separate message. This
2516 function does host-specific testing, and outputs the banner line.
2519 Returns: FALSE if the session can not continue; something has
2520 gone wrong, or the connection to the host is blocked
2524 smtp_start_session(void)
2527 uschar *user_msg, *log_msg;
2532 gettimeofday(&smtp_connection_start, NULL);
2533 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2534 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2537 /* Default values for certain variables */
2539 fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
2540 smtp_mailcmd_count = 0;
2541 count_nonmail = TRUE_UNSET;
2542 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2543 smtp_delay_mail = smtp_rlm_base;
2544 fl.auth_advertised = FALSE;
2545 f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
2546 f.pipelining_enable = TRUE;
2547 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2548 fl.smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2550 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2551 authentication settings from -oMaa to remain in force. */
2553 if (!host_checking && !f.sender_host_notsocket)
2554 sender_host_auth_pubname = sender_host_authenticated = NULL;
2555 authenticated_by = NULL;
2558 tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
2559 tls_in.ourcert = tls_in.peercert = NULL;
2561 tls_in.ocsp = OCSP_NOT_REQ;
2562 fl.tls_advertised = FALSE;
2564 fl.dsn_advertised = FALSE;
2566 fl.smtputf8_advertised = FALSE;
2569 /* Reset ACL connection variables */
2573 /* Allow for trailing 0 in the command and data buffers. Tainted. */
2575 smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, TRUE);
2577 smtp_cmd_buffer[0] = 0;
2578 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2580 /* For batched input, the protocol setting can be overridden from the
2581 command line by a trusted caller. */
2583 if (smtp_batched_input)
2585 if (!received_protocol) received_protocol = US"local-bsmtp";
2588 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2589 reset later if any of EHLO/AUTH/STARTTLS are received. */
2593 (sender_host_address ? protocols : protocols_local) [pnormal];
2595 /* Set up the buffer for inputting using direct read() calls, and arrange to
2596 call the local functions instead of the standard C ones. */
2600 receive_getc = smtp_getc;
2601 receive_getbuf = smtp_getbuf;
2602 receive_get_cache = smtp_get_cache;
2603 receive_hasc = smtp_hasc;
2604 receive_ungetc = smtp_ungetc;
2605 receive_feof = smtp_feof;
2606 receive_ferror = smtp_ferror;
2607 lwr_receive_getc = NULL;
2608 lwr_receive_getbuf = NULL;
2609 lwr_receive_hasc = NULL;
2610 lwr_receive_ungetc = NULL;
2612 /* Set up the message size limit; this may be host-specific */
2614 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2615 if (expand_string_message)
2617 if (thismessage_size_limit == -1)
2618 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2619 "%s", expand_string_message);
2621 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2622 "%s", expand_string_message);
2623 smtp_closedown(US"Temporary local problem - please try later");
2627 /* When a message is input locally via the -bs or -bS options, sender_host_
2628 unknown is set unless -oMa was used to force an IP address, in which case it
2629 is checked like a real remote connection. When -bs is used from inetd, this
2630 flag is not set, causing the sending host to be checked. The code that deals
2631 with IP source routing (if configured) is never required for -bs or -bS and
2632 the flag sender_host_notsocket is used to suppress it.
2634 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2635 reserve for certain hosts and/or networks. */
2637 if (!f.sender_host_unknown)
2640 BOOL reserved_host = FALSE;
2642 /* Look up IP options (source routing info) on the socket if this is not an
2643 -oMa "host", and if any are found, log them and drop the connection.
2645 Linux (and others now, see below) is different to everyone else, so there
2646 has to be some conditional compilation here. Versions of Linux before 2.1.15
2647 used a structure whose name was "options". Somebody finally realized that
2648 this name was silly, and it got changed to "ip_options". I use the
2649 newer name here, but there is a fudge in the script that sets up os.h
2650 to define a macro in older Linux systems.
2652 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2653 glibc 2, which has chosen ip_opts for the structure name. This is now
2654 really a glibc thing rather than a Linux thing, so the condition name
2655 has been changed to reflect this. It is relevant also to GNU/Hurd.
2657 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2658 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2659 a special macro defined in the os.h file.
2661 Some DGUX versions on older hardware appear not to support IP options at
2662 all, so there is now a general macro which can be set to cut out this
2665 How to do this properly in IPv6 is not yet known. */
2667 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2669 #ifdef GLIBC_IP_OPTIONS
2670 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2675 #elif defined DARWIN_IP_OPTIONS
2681 if (!host_checking && !f.sender_host_notsocket)
2684 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2685 struct ip_options *ipopt = store_get(optlen, FALSE);
2687 struct ip_opts ipoptblock;
2688 struct ip_opts *ipopt = &ipoptblock;
2689 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2691 struct ipoption ipoptblock;
2692 struct ipoption *ipopt = &ipoptblock;
2693 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2696 /* Occasional genuine failures of getsockopt() have been seen - for
2697 example, "reset by peer". Therefore, just log and give up on this
2698 call, unless the error is ENOPROTOOPT. This error is given by systems
2699 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2700 of writing. So for that error, carry on - we just can't do an IP options
2703 DEBUG(D_receive) debug_printf("checking for IP options\n");
2705 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2708 if (errno != ENOPROTOOPT)
2710 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2711 host_and_ident(FALSE), strerror(errno));
2712 smtp_printf("451 SMTP service not available\r\n", FALSE);
2717 /* Deal with any IP options that are set. On the systems I have looked at,
2718 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2719 more logging data than will fit in big_buffer. Nevertheless, after somebody
2720 questioned this code, I've added in some paranoid checking. */
2722 else if (optlen > 0)
2724 uschar *p = big_buffer;
2725 uschar *pend = big_buffer + big_buffer_size;
2728 struct in_addr addr;
2731 uschar *optstart = US (ipopt->__data);
2733 uschar *optstart = US (ipopt->ip_opts);
2735 uschar *optstart = US (ipopt->ipopt_list);
2738 DEBUG(D_receive) debug_printf("IP options exist\n");
2740 Ustrcpy(p, "IP options on incoming call:");
2743 for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
2756 if (!string_format(p, pend-p, " %s [@%s",
2757 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2759 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2761 inet_ntoa(ipopt->ip_dst)))
2763 inet_ntoa(ipopt->ipopt_dst)))
2771 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2773 while (optcount-- > 0)
2775 memcpy(&addr, adptr, sizeof(addr));
2776 if (!string_format(p, pend - p - 1, "%s%s",
2777 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2783 adptr += sizeof(struct in_addr);
2791 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2794 for (int i = 0; i < opt[1]; i++)
2795 p += sprintf(CS p, "%2.2x ", opt[i]);
2803 log_write(0, LOG_MAIN, "%s", big_buffer);
2805 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2807 log_write(0, LOG_MAIN|LOG_REJECT,
2808 "connection from %s refused (IP options)", host_and_ident(FALSE));
2810 smtp_printf("554 SMTP service not available\r\n", FALSE);
2814 /* Length of options = 0 => there are no options */
2816 else DEBUG(D_receive) debug_printf("no IP options found\n");
2818 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2820 /* Set keep-alive in socket options. The option is on by default. This
2821 setting is an attempt to get rid of some hanging connections that stick in
2822 read() when the remote end (usually a dialup) goes away. */
2824 if (smtp_accept_keepalive && !f.sender_host_notsocket)
2825 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2827 /* If the current host matches host_lookup, set the name by doing a
2828 reverse lookup. On failure, sender_host_name will be NULL and
2829 host_lookup_failed will be TRUE. This may or may not be serious - optional
2832 if (verify_check_host(&host_lookup) == OK)
2834 (void)host_name_lookup();
2835 host_build_sender_fullhost();
2838 /* Delay this until we have the full name, if it is looked up. */
2840 set_process_info("handling incoming connection from %s",
2841 host_and_ident(FALSE));
2843 /* Expand smtp_receive_timeout, if needed */
2845 if (smtp_receive_timeout_s)
2848 if ( !(exp = expand_string(smtp_receive_timeout_s))
2850 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2852 log_write(0, LOG_MAIN|LOG_PANIC,
2853 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2856 /* Test for explicit connection rejection */
2858 if (verify_check_host(&host_reject_connection) == OK)
2860 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2861 "from %s (host_reject_connection)", host_and_ident(FALSE));
2862 smtp_printf("554 SMTP service not available\r\n", FALSE);
2866 /* Test with TCP Wrappers if so configured. There is a problem in that
2867 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2868 such as disks dying. In these cases, it is desirable to reject with a 4xx
2869 error instead of a 5xx error. There isn't a "right" way to detect such
2870 problems. The following kludge is used: errno is zeroed before calling
2871 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2872 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2875 #ifdef USE_TCP_WRAPPERS
2877 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2878 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2879 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2880 expand_string_message);
2882 if (!hosts_ctl(tcp_wrappers_name,
2883 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2884 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2885 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2887 if (errno == 0 || errno == ENOENT)
2889 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2890 log_write(L_connection_reject,
2891 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2892 "(tcp wrappers)", host_and_ident(FALSE));
2893 smtp_printf("554 SMTP service not available\r\n", FALSE);
2897 int save_errno = errno;
2898 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2899 "errno value %d\n", save_errno);
2900 log_write(L_connection_reject,
2901 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2902 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2903 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2909 /* Check for reserved slots. The value of smtp_accept_count has already been
2910 incremented to include this process. */
2912 if (smtp_accept_max > 0 &&
2913 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2915 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2917 log_write(L_connection_reject,
2918 LOG_MAIN, "temporarily refused connection from %s: not in "
2919 "reserve list: connected=%d max=%d reserve=%d%s",
2920 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2921 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2922 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2923 "please try again later\r\n", FALSE, smtp_active_hostname);
2926 reserved_host = TRUE;
2929 /* If a load level above which only messages from reserved hosts are
2930 accepted is set, check the load. For incoming calls via the daemon, the
2931 check is done in the superior process if there are no reserved hosts, to
2932 save a fork. In all cases, the load average will already be available
2933 in a global variable at this point. */
2935 if (smtp_load_reserve >= 0 &&
2936 load_average > smtp_load_reserve &&
2938 verify_check_host(&smtp_reserve_hosts) != OK)
2940 log_write(L_connection_reject,
2941 LOG_MAIN, "temporarily refused connection from %s: not in "
2942 "reserve list and load average = %.2f", host_and_ident(FALSE),
2943 (double)load_average/1000.0);
2944 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2945 smtp_active_hostname);
2949 /* Determine whether unqualified senders or recipients are permitted
2950 for this host. Unfortunately, we have to do this every time, in order to
2951 set the flags so that they can be inspected when considering qualifying
2952 addresses in the headers. For a site that permits no qualification, this
2953 won't take long, however. */
2955 f.allow_unqualified_sender =
2956 verify_check_host(&sender_unqualified_hosts) == OK;
2958 f.allow_unqualified_recipient =
2959 verify_check_host(&recipient_unqualified_hosts) == OK;
2961 /* Determine whether HELO/EHLO is required for this host. The requirement
2962 can be hard or soft. */
2964 fl.helo_verify_required = verify_check_host(&helo_verify_hosts) == OK;
2965 if (!fl.helo_verify_required)
2966 fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2968 /* Determine whether this hosts is permitted to send syntactic junk
2969 after a HELO or EHLO command. */
2971 fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2974 /* For batch SMTP input we are now done. */
2976 if (smtp_batched_input) return TRUE;
2978 /* If valid Proxy Protocol source is connecting, set up session.
2979 Failure will not allow any SMTP function other than QUIT. */
2981 #ifdef SUPPORT_PROXY
2982 proxy_session = FALSE;
2983 f.proxy_session_failed = FALSE;
2984 if (check_proxy_protocol_host())
2985 setup_proxy_protocol_host();
2988 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2989 smtps port for use with older style SSL MTAs. */
2992 if (tls_in.on_connect)
2994 if (tls_server_start(&user_msg) != OK)
2995 return smtp_log_tls_fail(user_msg);
2996 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
3000 /* Run the connect ACL if it exists */
3003 if (acl_smtp_connect)
3006 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
3009 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
3014 /* Output the initial message for a two-way SMTP connection. It may contain
3015 newlines, which then cause a multi-line response to be given. */
3017 code = US"220"; /* Default status code */
3018 esc = US""; /* Default extended status code */
3019 esclen = 0; /* Length of esc */
3023 if (!(s = expand_string(smtp_banner)))
3024 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
3025 "failed: %s", smtp_banner, expand_string_message);
3031 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
3035 esclen = codelen - 4;
3039 /* Remove any terminating newlines; might as well remove trailing space too */
3042 while (p > s && isspace(p[-1])) p--;
3043 s = string_copyn(s, p-s);
3045 /* It seems that CC:Mail is braindead, and assumes that the greeting message
3046 is all contained in a single IP packet. The original code wrote out the
3047 greeting using several calls to fprint/fputc, and on busy servers this could
3048 cause it to be split over more than one packet - which caused CC:Mail to fall
3049 over when it got the second part of the greeting after sending its first
3050 command. Sigh. To try to avoid this, build the complete greeting message
3051 first, and output it in one fell swoop. This gives a better chance of it
3052 ending up as a single packet. */
3054 ss = string_get(256);
3057 do /* At least once, in case we have an empty string */
3060 uschar *linebreak = Ustrchr(p, '\n');
3061 ss = string_catn(ss, code, 3);
3065 ss = string_catn(ss, US" ", 1);
3069 len = linebreak - p;
3070 ss = string_catn(ss, US"-", 1);
3072 ss = string_catn(ss, esc, esclen);
3073 ss = string_catn(ss, p, len);
3074 ss = string_catn(ss, US"\r\n", 2);
3080 /* Before we write the banner, check that there is no input pending, unless
3081 this synchronisation check is disabled. */
3083 #ifndef DISABLE_PIPE_CONNECT
3084 fl.pipe_connect_acceptable =
3085 sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
3088 if (fl.pipe_connect_acceptable)
3089 f.smtp_in_early_pipe_used = TRUE;
3095 unsigned n = smtp_inend - smtp_inptr;
3096 if (n > 128) n = 128;
3098 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
3099 "synchronization error (input sent without waiting for greeting): "
3100 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
3101 string_printing(string_copyn(smtp_inptr, n)));
3102 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
3106 /* Now output the banner */
3107 /*XXX the ehlo-resp code does its own tls/nontls bit. Maybe subroutine that? */
3110 #ifndef DISABLE_PIPE_CONNECT
3111 fl.pipe_connect_acceptable && pipeline_connect_sends(),
3115 string_from_gstring(ss));
3117 /* Attempt to see if we sent the banner before the last ACK of the 3-way
3118 handshake arrived. If so we must have managed a TFO. */
3121 if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
3131 /*************************************************
3132 * Handle SMTP syntax and protocol errors *
3133 *************************************************/
3135 /* Write to the log for SMTP syntax errors in incoming commands, if configured
3136 to do so. Then transmit the error response. The return value depends on the
3137 number of syntax and protocol errors in this SMTP session.
3140 type error type, given as a log flag bit
3141 code response code; <= 0 means don't send a response
3142 data data to reflect in the response (can be NULL)
3143 errmess the error message
3145 Returns: -1 limit of syntax/protocol errors NOT exceeded
3146 +1 limit of syntax/protocol errors IS exceeded
3148 These values fit in with the values of the "done" variable in the main
3149 processing loop in smtp_setup_msg(). */
3152 synprot_error(int type, int code, uschar *data, uschar *errmess)
3156 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
3157 type == L_smtp_syntax_error ? "syntax" : "protocol",
3158 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
3160 if (++synprot_error_count > smtp_max_synprot_errors)
3163 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3164 "syntax or protocol errors (last command was \"%s\", %s)",
3165 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
3166 string_from_gstring(s_connhad_log(NULL))
3172 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
3173 data ? data : US"", data ? US": " : US"", errmess);
3175 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
3184 /*************************************************
3185 * Send SMTP response, possibly multiline *
3186 *************************************************/
3188 /* There are, it seems, broken clients out there that cannot handle multiline
3189 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3190 output nothing for non-final calls, and only the first line for anything else.
3193 code SMTP code, may involve extended status codes
3194 codelen length of smtp code; if > 4 there's an ESC
3195 final FALSE if the last line isn't the final line
3196 msg message text, possibly containing newlines
3202 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3207 if (!final && f.no_multiline_responses) return;
3212 esclen = codelen - 4;
3215 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3216 have had the same. Note: this code is also present in smtp_printf(). It would
3217 be tidier to have it only in one place, but when it was added, it was easier to
3218 do it that way, so as not to have to mess with the code for the RCPT command,
3219 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3221 if (fl.rcpt_in_progress)
3223 if (!rcpt_smtp_response)
3224 rcpt_smtp_response = string_copy(msg);
3225 else if (fl.rcpt_smtp_response_same &&
3226 Ustrcmp(rcpt_smtp_response, msg) != 0)
3227 fl.rcpt_smtp_response_same = FALSE;
3228 fl.rcpt_in_progress = FALSE;
3231 /* Now output the message, splitting it up into multiple lines if necessary.
3232 We only handle pipelining these responses as far as nonfinal/final groups,
3233 not the whole MAIL/RCPT/DATA response set. */
3237 uschar *nl = Ustrchr(msg, '\n');
3240 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3243 else if (nl[1] == 0 || f.no_multiline_responses)
3245 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3246 (int)(nl - msg), msg);
3251 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3253 Uskip_whitespace(&msg);
3261 /*************************************************
3262 * Parse user SMTP message *
3263 *************************************************/
3265 /* This function allows for user messages overriding the response code details
3266 by providing a suitable response code string at the start of the message
3267 user_msg. Check the message for starting with a response code and optionally an
3268 extended status code. If found, check that the first digit is valid, and if so,
3269 change the code pointer and length to use the replacement. An invalid code
3270 causes a panic log; in this case, if the log messages is the same as the user
3271 message, we must also adjust the value of the log message to show the code that
3272 is actually going to be used (the original one).
3274 This function is global because it is called from receive.c as well as within
3277 Note that the code length returned includes the terminating whitespace
3278 character, which is always included in the regex match.
3281 code SMTP code, may involve extended status codes
3282 codelen length of smtp code; if > 4 there's an ESC
3284 log_msg optional log message, to be adjusted with the new SMTP code
3285 check_valid if true, verify the response code
3291 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3297 if (!msg || !*msg || !regex_match(regex_smtp_code, *msg, -1, &match))
3300 len = Ustrlen(match);
3301 if (check_valid && (*msg)[0] != (*code)[0])
3303 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3304 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3305 if (log_msg && *log_msg == *msg)
3306 *log_msg = string_sprintf("%s %s", *code, *log_msg + len);
3311 *codelen = len; /* Includes final space */
3313 *msg += len; /* Chop the code off the message */
3320 /*************************************************
3321 * Handle an ACL failure *
3322 *************************************************/
3324 /* This function is called when acl_check() fails. As well as calls from within
3325 this module, it is called from receive.c for an ACL after DATA. It sorts out
3326 logging the incident, and sends the error response. A message containing
3327 newlines is turned into a multiline SMTP response, but for logging, only the
3330 There's a table of default permanent failure response codes to use in
3331 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3332 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3333 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3334 state, because there are broken clients that try VRFY before RCPT. A 5xx
3335 response should be given only when the address is positively known to be
3336 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3337 no explicit code, but if there is one we let it know best.
3338 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3340 From Exim 4.63, it is possible to override the response code details by
3341 providing a suitable response code string at the start of the message provided
3342 in user_msg. The code's first digit is checked for validity.
3345 where where the ACL was called from
3347 user_msg a message that can be included in an SMTP response
3348 log_msg a message for logging
3350 Returns: 0 in most cases
3351 2 if the failure code was FAIL_DROP, in which case the
3352 SMTP connection should be dropped (this value fits with the
3353 "done" variable in smtp_setup_msg() below)
3357 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3359 BOOL drop = rc == FAIL_DROP;
3363 uschar *sender_info = US"";
3366 if (drop) rc = FAIL;
3368 /* Set the default SMTP code, and allow a user message to change it. */
3370 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3371 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3372 where != ACL_WHERE_VRFY);
3374 /* We used to have sender_address here; however, there was a bug that was not
3375 updating sender_address after a rewrite during a verify. When this bug was
3376 fixed, sender_address at this point became the rewritten address. I'm not sure
3377 this is what should be logged, so I've changed to logging the unrewritten
3378 address to retain backward compatibility. */
3382 #ifdef WITH_CONTENT_SCAN
3383 case ACL_WHERE_MIME: what = US"during MIME ACL checks"; break;
3385 case ACL_WHERE_PREDATA: what = US"DATA"; break;
3386 case ACL_WHERE_DATA: what = US"after DATA"; break;
3387 #ifndef DISABLE_PRDR
3388 case ACL_WHERE_PRDR: what = US"after DATA PRDR"; break;
3392 uschar * place = smtp_cmd_data ? smtp_cmd_data : US"in \"connect\" ACL";
3395 if (where == ACL_WHERE_AUTH) /* avoid logging auth creds */
3398 for (s = smtp_cmd_data; *s && !isspace(*s); ) s++;
3399 lim = s - smtp_cmd_data; /* atop after method */
3401 what = string_sprintf("%s %.*s", acl_wherenames[where], lim, place);
3406 case ACL_WHERE_RCPT:
3407 case ACL_WHERE_DATA:
3408 #ifdef WITH_CONTENT_SCAN
3409 case ACL_WHERE_MIME:
3411 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3412 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3413 sender_host_authenticated ? US" A=" : US"",
3414 sender_host_authenticated ? sender_host_authenticated : US"",
3415 sender_host_authenticated && authenticated_id ? US":" : US"",
3416 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3421 /* If there's been a sender verification failure with a specific message, and
3422 we have not sent a response about it yet, do so now, as a preliminary line for
3423 failures, but not defers. However, always log it for defer, and log it for fail
3424 unless the sender_verify_fail log selector has been turned off. */
3426 if (sender_verified_failed &&
3427 !testflag(sender_verified_failed, af_sverify_told))
3429 BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
3430 fl.rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3432 setflag(sender_verified_failed, af_sverify_told);
3434 if (rc != FAIL || LOGGING(sender_verify_fail))
3435 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3436 host_and_ident(TRUE),
3437 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3438 sender_verified_failed->address,
3439 (sender_verified_failed->message == NULL)? US"" :
3440 string_sprintf(": %s", sender_verified_failed->message));
3442 if (rc == FAIL && sender_verified_failed->user_message)
3443 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3444 testflag(sender_verified_failed, af_verify_pmfail)?
3445 "Postmaster verification failed while checking <%s>\n%s\n"
3446 "Several RFCs state that you are required to have a postmaster\n"
3447 "mailbox for each mail domain. This host does not accept mail\n"
3448 "from domains whose servers reject the postmaster address."
3450 testflag(sender_verified_failed, af_verify_nsfail)?
3451 "Callback setup failed while verifying <%s>\n%s\n"
3452 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3453 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3454 "RFC requirements, and stops you from receiving standard bounce\n"
3455 "messages. This host does not accept mail from domains whose servers\n"
3458 "Verification failed for <%s>\n%s",
3459 sender_verified_failed->address,
3460 sender_verified_failed->user_message));
3462 fl.rcpt_in_progress = save_rcpt_in_progress;
3465 /* Sort out text for logging */
3467 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3468 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3470 /* Send permanent failure response to the command, but the code used isn't
3471 always a 5xx one - see comments at the start of this function. If the original
3472 rc was FAIL_DROP we drop the connection and yield 2. */
3475 smtp_respond(smtp_code, codelen, TRUE,
3476 user_msg ? user_msg : US"Administrative prohibition");
3478 /* Send temporary failure response to the command. Don't give any details,
3479 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3480 verb, and for a header verify when smtp_return_error_details is set.
3482 This conditional logic is all somewhat of a mess because of the odd
3483 interactions between temp_details and return_error_details. One day it should
3484 be re-implemented in a tidier fashion. */
3487 if (f.acl_temp_details && user_msg)
3489 if ( smtp_return_error_details
3490 && sender_verified_failed
3491 && sender_verified_failed->message
3493 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3495 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3498 smtp_respond(smtp_code, codelen, TRUE,
3499 US"Temporary local problem - please try later");
3501 /* Log the incident to the logs that are specified by log_reject_target
3502 (default main, reject). This can be empty to suppress logging of rejections. If
3503 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3504 is closing if required and return 2. */
3506 if (log_reject_target != 0)
3509 gstring * g = s_tlslog(NULL);
3510 uschar * tls = string_from_gstring(g);
3511 if (!tls) tls = US"";
3513 uschar * tls = US"";
3515 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3516 log_reject_target, "%s%s%s %s%srejected %s%s",
3517 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3518 host_and_ident(TRUE),
3521 rc == FAIL ? US"" : US"temporarily ",
3525 if (!drop) return 0;
3527 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3528 smtp_get_connection_info());
3530 /* Run the not-quit ACL, but without any custom messages. This should not be a
3531 problem, because we get here only if some other ACL has issued "drop", and
3532 in that case, *its* custom messages will have been used above. */
3534 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3541 /*************************************************
3542 * Handle SMTP exit when QUIT is not given *
3543 *************************************************/
3545 /* This function provides a logging/statistics hook for when an SMTP connection
3546 is dropped on the floor or the other end goes away. It's a global function
3547 because it's called from receive.c as well as this module. As well as running
3548 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3549 response, either with a custom message from the ACL, or using a default. There
3550 is one case, however, when no message is output - after "drop". In that case,
3551 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3552 passed to this function.
3554 In case things go wrong while processing this function, causing an error that
3555 may re-enter this function, there is a recursion check.
3558 reason What $smtp_notquit_reason will be set to in the ACL;
3559 if NULL, the ACL is not run
3560 code The error code to return as part of the response
3561 defaultrespond The default message if there's no user_msg
3567 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3570 uschar *user_msg = NULL;
3571 uschar *log_msg = NULL;
3573 /* Check for recursive call */
3575 if (fl.smtp_exit_function_called)
3577 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3581 fl.smtp_exit_function_called = TRUE;
3583 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3585 if (acl_smtp_notquit && reason)
3587 smtp_notquit_reason = reason;
3588 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3589 &log_msg)) == ERROR)
3590 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3594 /* If the connection was dropped, we certainly are no longer talking TLS */
3595 tls_in.active.sock = -1;
3597 /* Write an SMTP response if we are expected to give one. As the default
3598 responses are all internal, they should be reasonable size. */
3600 if (code && defaultrespond)
3603 smtp_respond(code, 3, TRUE, user_msg);
3609 va_start(ap, defaultrespond);
3610 g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, CS defaultrespond, ap);
3612 smtp_printf("%s %s\r\n", FALSE, code, string_from_gstring(g));
3621 /*************************************************
3622 * Verify HELO argument *
3623 *************************************************/
3625 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3626 matched. It is also called from ACL processing if verify = helo is used and
3627 verification was not previously tried (i.e. helo_try_verify_hosts was not
3628 matched). The result of its processing is to set helo_verified and
3629 helo_verify_failed. These variables should both be FALSE for this function to
3632 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3633 for IPv6 ::ffff: literals.
3636 Returns: TRUE if testing was completed;
3637 FALSE on a temporary failure
3641 smtp_verify_helo(void)
3645 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3648 if (sender_helo_name == NULL)
3650 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3653 /* Deal with the case of -bs without an IP address */
3655 else if (sender_host_address == NULL)
3657 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3658 f.helo_verified = TRUE;
3661 /* Deal with the more common case when there is a sending IP address */
3663 else if (sender_helo_name[0] == '[')
3665 f.helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3666 Ustrlen(sender_host_address)) == 0;
3669 if (!f.helo_verified)
3671 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3672 f.helo_verified = Ustrncmp(sender_helo_name + 1,
3673 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3678 { if (f.helo_verified) debug_printf("matched host address\n"); }
3681 /* Do a reverse lookup if one hasn't already given a positive or negative
3682 response. If that fails, or the name doesn't match, try checking with a forward
3687 if (sender_host_name == NULL && !host_lookup_failed)
3688 yield = host_name_lookup() != DEFER;
3690 /* If a host name is known, check it and all its aliases. */
3692 if (sender_host_name)
3693 if ((f.helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3695 sender_helo_dnssec = sender_host_dnssec;
3696 HDEBUG(D_receive) debug_printf("matched host name\n");
3700 uschar **aliases = sender_host_aliases;
3702 if ((f.helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3704 sender_helo_dnssec = sender_host_dnssec;
3708 HDEBUG(D_receive) if (f.helo_verified)
3709 debug_printf("matched alias %s\n", *(--aliases));
3712 /* Final attempt: try a forward lookup of the helo name */
3714 if (!f.helo_verified)
3718 {.name = sender_helo_name, .address = NULL, .mx = MX_NONE, .next = NULL};
3720 {.request = US"*", .require = US""};
3722 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
3724 rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
3725 NULL, NULL, NULL, &d, NULL, NULL);
3726 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
3727 for (host_item * hh = &h; hh; hh = hh->next)
3728 if (Ustrcmp(hh->address, sender_host_address) == 0)
3730 f.helo_verified = TRUE;
3731 if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
3733 debug_printf("IP address for %s matches calling address\n"
3734 "Forward DNS security status: %sverified\n",
3735 sender_helo_name, sender_helo_dnssec ? "" : "un");
3741 if (!f.helo_verified) f.helo_verify_failed = TRUE; /* We've tried ... */
3748 /*************************************************
3749 * Send user response message *
3750 *************************************************/
3752 /* This function is passed a default response code and a user message. It calls
3753 smtp_message_code() to check and possibly modify the response code, and then
3754 calls smtp_respond() to transmit the response. I put this into a function
3755 just to avoid a lot of repetition.
3758 code the response code
3759 user_msg the user message
3765 smtp_user_msg(uschar *code, uschar *user_msg)
3768 smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
3769 smtp_respond(code, len, TRUE, user_msg);
3775 smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
3777 const uschar *set_id = NULL;
3780 /* Run the checking code, passing the remainder of the command line as
3781 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
3782 it as the only set numerical variable. The authenticator may set $auth<n>
3783 and also set other numeric variables. The $auth<n> variables are preferred
3784 nowadays; the numerical variables remain for backwards compatibility.
3786 Afterwards, have a go at expanding the set_id string, even if
3787 authentication failed - for bad passwords it can be useful to log the
3788 userid. On success, require set_id to expand and exist, and put it in
3789 authenticated_id. Save this in permanent store, as the working store gets
3790 reset at HELO, RSET, etc. */
3792 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
3794 expand_nlength[0] = 0; /* $0 contains nothing */
3796 rc = (au->info->servercode)(au, smtp_cmd_data);
3797 if (au->set_id) set_id = expand_string(au->set_id);
3798 expand_nmax = -1; /* Reset numeric variables */
3799 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
3801 /* The value of authenticated_id is stored in the spool file and printed in
3802 log lines. It must not contain binary zeros or newline characters. In
3803 normal use, it never will, but when playing around or testing, this error
3804 can (did) happen. To guard against this, ensure that the id contains only
3805 printing characters. */
3807 if (set_id) set_id = string_printing(set_id);
3809 /* For the non-OK cases, set up additional logging data if set_id
3813 set_id = set_id && *set_id
3814 ? string_sprintf(" (set_id=%s)", set_id) : US"";
3816 /* Switch on the result */
3821 if (!au->set_id || set_id) /* Complete success */
3823 if (set_id) authenticated_id = string_copy_perm(set_id, TRUE);
3824 sender_host_authenticated = au->name;
3825 sender_host_auth_pubname = au->public_name;
3826 authentication_failed = FALSE;
3827 authenticated_fail_id = NULL; /* Impossible to already be set? */
3830 (sender_host_address ? protocols : protocols_local)
3831 [pextend + pauthed + (tls_in.active.sock >= 0 ? pcrpted:0)];
3832 *s = *ss = US"235 Authentication succeeded";
3833 authenticated_by = au;
3837 /* Authentication succeeded, but we failed to expand the set_id string.
3838 Treat this as a temporary error. */
3840 auth_defer_msg = expand_string_message;
3844 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3845 *s = string_sprintf("435 Unable to authenticate at present%s",
3846 auth_defer_user_msg);
3847 *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
3848 set_id, auth_defer_msg);
3852 *s = *ss = US"501 Invalid base64 data";
3856 *s = *ss = US"501 Authentication cancelled";
3860 *s = *ss = US"553 Initial data not expected";
3864 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3865 *s = US"535 Incorrect authentication data";
3866 *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
3870 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3871 *s = US"435 Internal error";
3872 *ss = string_sprintf("435 Internal error%s: return %d from authentication "
3873 "check", set_id, rc);
3885 qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
3888 if (f.allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
3890 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3892 rd = Ustrlen(recipient) + 1;
3893 /* deconst ok as *recipient was not const */
3894 *recipient = US rewrite_address_qualify(*recipient, TRUE);
3897 smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
3899 log_write(L_smtp_syntax_error,
3900 LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
3901 tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
3909 smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
3912 f.smtp_in_quit = TRUE;
3913 incomplete_transaction_log(US"QUIT");
3915 && acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp)
3917 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3920 #ifdef EXIM_TCP_CORK
3921 (void) setsockopt(fileno(smtp_out), IPPROTO_TCP, EXIM_TCP_CORK, US &on, sizeof(on));
3925 smtp_respond(US"221", 3, TRUE, *user_msgp);
3927 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
3929 #ifdef SERVERSIDE_CLOSE_NOWAIT
3930 # ifndef DISABLE_TLS
3931 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
3934 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3935 smtp_get_connection_info());
3938 # ifndef DISABLE_TLS
3939 tls_close(NULL, TLS_SHUTDOWN_WAIT);
3942 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3943 smtp_get_connection_info());
3945 /* Pause, hoping client will FIN first so that they get the TIME_WAIT.
3946 The socket should become readble (though with no data) */
3948 (void) poll_one_fd(fileno(smtp_in), POLLIN, 200);
3949 #endif /*!SERVERSIDE_CLOSE_NOWAIT*/
3954 smtp_rset_handler(void)
3957 incomplete_transaction_log(US"RSET");
3958 smtp_printf("250 Reset OK\r\n", FALSE);
3959 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3964 expand_mailmax(const uschar * s)
3966 if (!(s = expand_cstring(s)))
3967 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand smtp_accept_max_per_connection");
3968 return *s ? Uatoi(s) : 0;
3971 /*************************************************
3972 * Initialize for SMTP incoming message *
3973 *************************************************/
3975 /* This function conducts the initial dialogue at the start of an incoming SMTP
3976 message, and builds a list of recipients. However, if the incoming message
3977 is part of a batch (-bS option) a separate function is called since it would
3978 be messy having tests splattered about all over this function. This function
3979 therefore handles the case where interaction is occurring. The input and output
3980 files are set up in smtp_in and smtp_out.
3982 The global recipients_list is set to point to a vector of recipient_item
3983 blocks, whose number is given by recipients_count. This is extended by the
3984 receive_add_recipient() function. The global variable sender_address is set to
3985 the sender's address. The yield is +1 if a message has been successfully
3986 started, 0 if a QUIT command was encountered or the connection was refused from
3987 the particular host, or -1 if the connection was lost.
3991 Returns: > 0 message successfully started (reached DATA)
3992 = 0 QUIT read or end of file reached or call refused
3997 smtp_setup_msg(void)
4000 BOOL toomany = FALSE;
4001 BOOL discarded = FALSE;
4002 BOOL last_was_rej_mail = FALSE;
4003 BOOL last_was_rcpt = FALSE;
4004 rmark reset_point = store_mark();
4006 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
4008 /* Reset for start of new message. We allow one RSET not to be counted as a
4009 nonmail command, for those MTAs that insist on sending it between every
4010 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
4011 TLS between messages (an Exim client may do this if it has messages queued up
4012 for the host). Note: we do NOT reset AUTH at this point. */
4014 reset_point = smtp_reset(reset_point);
4015 message_ended = END_NOTSTARTED;
4017 chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
4019 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
4020 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
4021 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
4023 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
4026 if (lwr_receive_getc != NULL)
4028 /* This should have already happened, but if we've gotten confused,
4029 force a reset here. */
4030 DEBUG(D_receive) debug_printf("WARNING: smtp_setup_msg had to restore receive functions to lowers\n");
4031 bdat_pop_receive_functions();
4034 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
4036 had_command_sigterm = 0;
4037 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
4039 /* Batched SMTP is handled in a different function. */
4041 if (smtp_batched_input) return smtp_setup_batch_msg();
4044 if (smtp_in) /* Avoid pure-ACKs while in cmd pingpong phase */
4045 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
4046 US &off, sizeof(off));
4049 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
4050 value. The values are 2 larger than the required yield of the function. */
4054 const uschar **argv;
4055 uschar *etrn_command;
4056 uschar *etrn_serialize_key;
4058 uschar *log_msg, *smtp_code;
4059 uschar *user_msg = NULL;
4060 uschar *recipient = NULL;
4061 uschar *hello = NULL;
4063 BOOL was_rej_mail = FALSE;
4064 BOOL was_rcpt = FALSE;
4065 void (*oldsignal)(int);
4067 int start, end, sender_domain, recipient_domain;
4070 uschar *orcpt = NULL;
4075 /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
4076 if ( tls_in.active.sock >= 0
4078 && tls_in.certificate_verified
4079 && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
4082 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
4084 for (auth_instance * au = auths; au; au = au->next)
4085 if (strcmpic(US"tls", au->driver_name) == 0)
4088 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4089 &user_msg, &log_msg)) != OK
4091 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4094 smtp_cmd_data = NULL;
4096 if (smtp_in_auth(au, &s, &ss) == OK)
4097 { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
4099 { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
4106 switch(smtp_read_command(
4107 #ifndef DISABLE_PIPE_CONNECT
4108 !fl.pipe_connect_acceptable,
4112 GETC_BUFFER_UNLIMITED))
4114 /* The AUTH command is not permitted to occur inside a transaction, and may
4115 occur successfully only once per connection. Actually, that isn't quite
4116 true. When TLS is started, all previous information about a connection must
4117 be discarded, so a new AUTH is permitted at that time.
4119 AUTH may only be used when it has been advertised. However, it seems that
4120 there are clients that send AUTH when it hasn't been advertised, some of
4121 them even doing this after HELO. And there are MTAs that accept this. Sigh.
4122 So there's a get-out that allows this to happen.
4124 AUTH is initially labelled as a "nonmail command" so that one occurrence
4125 doesn't get counted. We change the label here so that multiple failing
4126 AUTHS will eventually hit the nonmail threshold. */
4130 authentication_failed = TRUE;
4131 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
4133 if (!fl.auth_advertised && !f.allow_auth_unadvertised)
4135 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4136 US"AUTH command used when not advertised");
4139 if (sender_host_authenticated)
4141 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4142 US"already authenticated");
4147 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4148 US"not permitted in mail transaction");
4155 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4156 &user_msg, &log_msg)) != OK
4159 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4163 /* Find the name of the requested authentication mechanism. */
4166 for (; (c = *smtp_cmd_data) && !isspace(c); smtp_cmd_data++)
4167 if (!isalnum(c) && c != '-' && c != '_')
4169 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4170 US"invalid character in authentication mechanism name");
4174 /* If not at the end of the line, we must be at white space. Terminate the
4175 name and move the pointer on to any data that may be present. */
4179 *smtp_cmd_data++ = 0;
4180 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
4183 /* Search for an authentication mechanism which is configured for use
4184 as a server and which has been advertised (unless, sigh, allow_auth_
4185 unadvertised is set). */
4189 for (au = auths; au; au = au->next)
4190 if (strcmpic(s, au->public_name) == 0 && au->server &&
4191 (au->advertised || f.allow_auth_unadvertised))
4196 c = smtp_in_auth(au, &s, &ss);
4198 smtp_printf("%s\r\n", FALSE, s);
4200 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
4201 au->name, host_and_ident(FALSE), ss);
4204 done = synprot_error(L_smtp_protocol_error, 504, NULL,
4205 string_sprintf("%s authentication mechanism not supported", s));
4208 break; /* AUTH_CMD */
4210 /* The HELO/EHLO commands are permitted to appear in the middle of a
4211 session as well as at the beginning. They have the effect of a reset in
4212 addition to their other functions. Their absence at the start cannot be
4213 taken to be an error.
4217 If the EHLO command is not acceptable to the SMTP server, 501, 500,
4218 or 502 failure replies MUST be returned as appropriate. The SMTP
4219 server MUST stay in the same state after transmitting these replies
4220 that it was in before the EHLO was received.
4222 Therefore, we do not do the reset until after checking the command for
4223 acceptability. This change was made for Exim release 4.11. Previously
4224 it did the reset first. */
4237 HELO_EHLO: /* Common code for HELO and EHLO */
4238 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
4239 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
4241 /* Reject the HELO if its argument was invalid or non-existent. A
4242 successful check causes the argument to be saved in malloc store. */
4244 if (!check_helo(smtp_cmd_data))
4246 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
4248 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
4249 "invalid argument(s): %s", hello, host_and_ident(FALSE),
4250 *smtp_cmd_argument == 0 ? US"(no argument given)" :
4251 string_printing(smtp_cmd_argument));
4253 if (++synprot_error_count > smtp_max_synprot_errors)
4255 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4256 "syntax or protocol errors (last command was \"%s\", %s)",
4257 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
4258 string_from_gstring(s_connhad_log(NULL))
4266 /* If sender_host_unknown is true, we have got here via the -bs interface,
4267 not called from inetd. Otherwise, we are running an IP connection and the
4268 host address will be set. If the helo name is the primary name of this
4269 host and we haven't done a reverse lookup, force one now. If helo_verify_required
4270 is set, ensure that the HELO name matches the actual host. If helo_verify
4271 is set, do the same check, but softly. */
4273 if (!f.sender_host_unknown)
4275 BOOL old_helo_verified = f.helo_verified;
4276 uschar *p = smtp_cmd_data;
4278 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
4281 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
4282 because otherwise the log can be confusing. */
4284 if ( !sender_host_name
4285 && match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
4286 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL) == OK)
4287 (void)host_name_lookup();
4289 /* Rebuild the fullhost info to include the HELO name (and the real name
4290 if it was looked up.) */
4292 host_build_sender_fullhost(); /* Rebuild */
4293 set_process_info("handling%s incoming connection from %s",
4294 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
4296 /* Verify if configured. This doesn't give much security, but it does
4297 make some people happy to be able to do it. If helo_verify_required is set,
4298 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
4299 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
4300 now obsolescent, since the verification can now be requested selectively
4303 f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
4304 if (fl.helo_verify_required || fl.helo_verify)
4306 BOOL tempfail = !smtp_verify_helo();
4307 if (!f.helo_verified)
4309 if (fl.helo_verify_required)
4311 smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
4312 tempfail? 451 : 550, hello);
4313 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
4314 tempfail? "temporarily " : "",
4315 hello, sender_helo_name, host_and_ident(FALSE));
4316 f.helo_verified = old_helo_verified;
4317 break; /* End of HELO/EHLO processing */
4319 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
4320 "helo_try_verify_hosts\n", hello);
4326 /* set up SPF context */
4327 spf_conn_init(sender_helo_name, sender_host_address);
4330 /* Apply an ACL check if one is defined; afterwards, recheck
4331 synchronization in case the client started sending in a delay. */
4334 if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
4335 &user_msg, &log_msg)) != OK)
4337 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
4338 sender_helo_name = NULL;
4339 host_build_sender_fullhost(); /* Rebuild */
4342 #ifndef DISABLE_PIPE_CONNECT
4343 else if (!fl.pipe_connect_acceptable && !check_sync())
4345 else if (!check_sync())
4349 /* Generate an OK reply. The default string includes the ident if present,
4350 and also the IP address if present. Reflecting back the ident is intended
4351 as a deterrent to mail forgers. For maximum efficiency, and also because
4352 some broken systems expect each response to be in a single packet, arrange
4353 that the entire reply is sent in one write(). */
4355 fl.auth_advertised = FALSE;
4356 f.smtp_in_pipelining_advertised = FALSE;
4358 fl.tls_advertised = FALSE;
4360 fl.dsn_advertised = FALSE;
4362 fl.smtputf8_advertised = FALSE;
4365 /* Expand the per-connection message count limit option */
4366 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4368 smtp_code = US"250 "; /* Default response code plus space*/
4371 /* sender_host_name below will be tainted, so save on copy when we hit it */
4372 g = string_get_tainted(24, TRUE);
4373 g = string_fmt_append(g, "%.3s %s Hello %s%s%s",
4375 smtp_active_hostname,
4376 sender_ident ? sender_ident : US"",
4377 sender_ident ? US" at " : US"",
4378 sender_host_name ? sender_host_name : sender_helo_name);
4380 if (sender_host_address)
4381 g = string_fmt_append(g, " [%s]", sender_host_address);
4384 /* A user-supplied EHLO greeting may not contain more than one line. Note
4385 that the code returned by smtp_message_code() includes the terminating
4386 whitespace character. */
4392 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
4393 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
4394 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
4396 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
4397 "newlines: message truncated: %s", string_printing(s));
4400 g = string_cat(NULL, s);
4403 g = string_catn(g, US"\r\n", 2);
4405 /* If we received EHLO, we must create a multiline response which includes
4406 the functions supported. */
4412 /* I'm not entirely happy with this, as an MTA is supposed to check
4413 that it has enough room to accept a message of maximum size before
4414 it sends this. However, there seems little point in not sending it.
4415 The actual size check happens later at MAIL FROM time. By postponing it
4416 till then, VRFY and EXPN can be used after EHLO when space is short. */
4418 if (thismessage_size_limit > 0)
4419 g = string_fmt_append(g, "%.3s-SIZE %d\r\n", smtp_code,
4420 thismessage_size_limit);
4423 g = string_catn(g, smtp_code, 3);
4424 g = string_catn(g, US"-SIZE\r\n", 7);
4427 #ifdef EXPERIMENTAL_ESMTP_LIMITS
4428 if ( (smtp_mailcmd_max > 0 || recipients_max)
4429 && verify_check_host(&limits_advertise_hosts) == OK)
4431 g = string_fmt_append(g, "%.3s-LIMITS", smtp_code);
4432 if (smtp_mailcmd_max > 0)
4433 g = string_fmt_append(g, " MAILMAX=%d", smtp_mailcmd_max);
4435 g = string_fmt_append(g, " RCPTMAX=%d", recipients_max);
4436 g = string_catn(g, US"\r\n", 2);
4440 /* Exim does not do protocol conversion or data conversion. It is 8-bit
4441 clean; if it has an 8-bit character in its hand, it just sends it. It
4442 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
4443 However, some users want this option simply in order to stop MUAs
4444 mangling messages that contain top-bit-set characters. It is therefore
4445 provided as an option. */
4447 if (accept_8bitmime)
4449 g = string_catn(g, smtp_code, 3);
4450 g = string_catn(g, US"-8BITMIME\r\n", 11);
4453 /* Advertise DSN support if configured to do so. */
4454 if (verify_check_host(&dsn_advertise_hosts) != FAIL)
4456 g = string_catn(g, smtp_code, 3);
4457 g = string_catn(g, US"-DSN\r\n", 6);
4458 fl.dsn_advertised = TRUE;
4461 /* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
4462 permitted to issue them; a check is made when any host actually tries. */
4466 g = string_catn(g, smtp_code, 3);
4467 g = string_catn(g, US"-ETRN\r\n", 7);
4471 g = string_catn(g, smtp_code, 3);
4472 g = string_catn(g, US"-VRFY\r\n", 7);
4476 g = string_catn(g, smtp_code, 3);
4477 g = string_catn(g, US"-EXPN\r\n", 7);
4480 /* Exim is quite happy with pipelining, so let the other end know that
4481 it is safe to use it, unless advertising is disabled. */
4483 if ( f.pipelining_enable
4484 && verify_check_host(&pipelining_advertise_hosts) == OK)
4486 g = string_catn(g, smtp_code, 3);
4487 g = string_catn(g, US"-PIPELINING\r\n", 13);
4488 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
4489 f.smtp_in_pipelining_advertised = TRUE;
4491 #ifndef DISABLE_PIPE_CONNECT
4492 if (fl.pipe_connect_acceptable)
4494 f.smtp_in_early_pipe_advertised = TRUE;
4495 g = string_catn(g, smtp_code, 3);
4496 g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
4502 /* If any server authentication mechanisms are configured, advertise
4503 them if the current host is in auth_advertise_hosts. The problem with
4504 advertising always is that some clients then require users to
4505 authenticate (and aren't configurable otherwise) even though it may not
4506 be necessary (e.g. if the host is in host_accept_relay).
4508 RFC 2222 states that SASL mechanism names contain only upper case
4509 letters, so output the names in upper case, though we actually recognize
4510 them in either case in the AUTH command. */
4514 && !sender_host_authenticated
4516 && verify_check_host(&auth_advertise_hosts) == OK
4520 for (auth_instance * au = auths; au; au = au->next)
4522 au->advertised = FALSE;
4525 DEBUG(D_auth+D_expand) debug_printf_indent(
4526 "Evaluating advertise_condition for %s %s athenticator\n",
4527 au->name, au->public_name);
4528 if ( !au->advertise_condition
4529 || expand_check_condition(au->advertise_condition, au->name,
4536 g = string_catn(g, smtp_code, 3);
4537 g = string_catn(g, US"-AUTH", 5);
4539 fl.auth_advertised = TRUE;
4542 g = string_catn(g, US" ", 1);
4543 g = string_cat (g, au->public_name);
4544 while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
4545 au->advertised = TRUE;
4550 if (!first) g = string_catn(g, US"\r\n", 2);
4553 /* RFC 3030 CHUNKING */
4555 if (verify_check_host(&chunking_advertise_hosts) != FAIL)
4557 g = string_catn(g, smtp_code, 3);
4558 g = string_catn(g, US"-CHUNKING\r\n", 11);
4559 f.chunking_offered = TRUE;
4560 chunking_state = CHUNKING_OFFERED;
4563 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
4564 if it has been included in the binary, and the host matches
4565 tls_advertise_hosts. We must *not* advertise if we are already in a
4566 secure connection. */
4569 if (tls_in.active.sock < 0 &&
4570 verify_check_host(&tls_advertise_hosts) != FAIL)
4572 g = string_catn(g, smtp_code, 3);
4573 g = string_catn(g, US"-STARTTLS\r\n", 11);
4574 fl.tls_advertised = TRUE;
4578 #ifndef DISABLE_PRDR
4579 /* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
4582 g = string_catn(g, smtp_code, 3);
4583 g = string_catn(g, US"-PRDR\r\n", 7);
4588 if ( accept_8bitmime
4589 && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
4591 g = string_catn(g, smtp_code, 3);
4592 g = string_catn(g, US"-SMTPUTF8\r\n", 11);
4593 fl.smtputf8_advertised = TRUE;
4597 /* Finish off the multiline reply with one that is always available. */
4599 g = string_catn(g, smtp_code, 3);
4600 g = string_catn(g, US" HELP\r\n", 7);
4603 /* Terminate the string (for debug), write it, and note that HELO/EHLO
4607 if (tls_in.active.sock >= 0)
4608 (void)tls_write(NULL, g->s, g->ptr,
4609 # ifndef DISABLE_PIPE_CONNECT
4610 fl.pipe_connect_acceptable && pipeline_connect_sends());
4616 (void) fwrite(g->s, 1, g->ptr, smtp_out);
4622 (void) string_from_gstring(g);
4623 while ((cr = Ustrchr(g->s, '\r')) != NULL) /* lose CRs */
4624 memmove(cr, cr + 1, (g->ptr--) - (cr - g->s));
4625 debug_printf("SMTP>> %s", g->s);
4627 fl.helo_seen = TRUE;
4629 /* Reset the protocol and the state, abandoning any previous message. */
4631 (sender_host_address ? protocols : protocols_local)
4633 ? pextend + (sender_host_authenticated ? pauthed : 0)
4635 + (tls_in.active.sock >= 0 ? pcrpted : 0)
4637 cancel_cutthrough_connection(TRUE, US"sent EHLO response");
4638 reset_point = smtp_reset(reset_point);
4640 break; /* HELO/EHLO */
4643 /* The MAIL command requires an address as an operand. All we do
4644 here is to parse it for syntactic correctness. The form "<>" is
4645 a special case which converts into an empty string. The start/end
4646 pointers in the original are not used further for this address, as
4647 it is the canonical extracted address which is all that is kept. */
4651 smtp_mailcmd_count++; /* Count for limit and ratelimit */
4653 was_rej_mail = TRUE; /* Reset if accepted */
4654 env_mail_type_t * mail_args; /* Sanity check & validate args */
4657 if ( fl.helo_verify_required
4658 || verify_check_host(&hosts_require_helo) == OK)
4660 smtp_printf("503 HELO or EHLO required\r\n", FALSE);
4661 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
4662 "HELO/EHLO given", host_and_ident(FALSE));
4665 else if (smtp_mailcmd_max < 0)
4666 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4670 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4671 US"sender already given");
4675 if (!*smtp_cmd_data)
4677 done = synprot_error(L_smtp_protocol_error, 501, NULL,
4678 US"MAIL must have an address operand");
4682 /* Check to see if the limit for messages per connection would be
4683 exceeded by accepting further messages. */
4685 if (smtp_mailcmd_max > 0 && smtp_mailcmd_count > smtp_mailcmd_max)
4687 smtp_printf("421 too many messages in this connection\r\n", FALSE);
4688 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
4689 "messages in one connection", host_and_ident(TRUE));
4693 /* Reset for start of message - even if this is going to fail, we
4694 obviously need to throw away any previous data. */
4696 cancel_cutthrough_connection(TRUE, US"MAIL received");
4697 reset_point = smtp_reset(reset_point);
4699 sender_data = recipient_data = NULL;
4701 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
4703 if (fl.esmtp) for(;;)
4705 uschar *name, *value, *end;
4706 unsigned long int size;
4707 BOOL arg_error = FALSE;
4709 if (!extract_option(&name, &value)) break;
4711 for (mail_args = env_mail_type_list;
4712 mail_args->value != ENV_MAIL_OPT_NULL;
4715 if (strcmpic(name, mail_args->name) == 0)
4717 if (mail_args->need_value && strcmpic(value, US"") == 0)
4720 switch(mail_args->value)
4722 /* Handle SIZE= by reading the value. We don't do the check till later,
4723 in order to be able to log the sender address on failure. */
4724 case ENV_MAIL_OPT_SIZE:
4725 if (((size = Ustrtoul(value, &end, 10)), *end == 0))
4727 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
4729 message_size = (int)size;
4735 /* If this session was initiated with EHLO and accept_8bitmime is set,
4736 Exim will have indicated that it supports the BODY=8BITMIME option. In
4737 fact, it does not support this according to the RFCs, in that it does not
4738 take any special action for forwarding messages containing 8-bit
4739 characters. That is why accept_8bitmime is not the default setting, but
4740 some sites want the action that is provided. We recognize both "8BITMIME"
4741 and "7BIT" as body types, but take no action. */
4742 case ENV_MAIL_OPT_BODY:
4743 if (accept_8bitmime) {
4744 if (strcmpic(value, US"8BITMIME") == 0)
4746 else if (strcmpic(value, US"7BIT") == 0)
4751 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4752 US"invalid data for BODY");
4755 DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
4761 /* Handle the two DSN options, but only if configured to do so (which
4762 will have caused "DSN" to be given in the EHLO response). The code itself
4763 is included only if configured in at build time. */
4765 case ENV_MAIL_OPT_RET:
4766 if (fl.dsn_advertised)
4768 /* Check if RET has already been set */
4771 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4772 US"RET can be specified once only");
4775 dsn_ret = strcmpic(value, US"HDRS") == 0
4777 : strcmpic(value, US"FULL") == 0
4780 DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
4781 /* Check for invalid invalid value, and exit with error */
4784 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4785 US"Value for RET is invalid");
4790 case ENV_MAIL_OPT_ENVID:
4791 if (fl.dsn_advertised)
4793 /* Check if the dsn envid has been already set */
4796 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4797 US"ENVID can be specified once only");
4800 dsn_envid = string_copy(value);
4801 DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
4805 /* Handle the AUTH extension. If the value given is not "<>" and either
4806 the ACL says "yes" or there is no ACL but the sending host is
4807 authenticated, we set it up as the authenticated sender. However, if the
4808 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
4809 the condition is met. The value of AUTH is an xtext, which means that +,
4810 = and cntrl chars are coded in hex; however "<>" is unaffected by this
4812 case ENV_MAIL_OPT_AUTH:
4813 if (Ustrcmp(value, "<>") != 0)
4818 if (auth_xtextdecode(value, &authenticated_sender) < 0)
4820 /* Put back terminator overrides for error message */
4823 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4824 US"invalid data for AUTH");
4827 if (!acl_smtp_mailauth)
4829 ignore_msg = US"client not authenticated";
4830 rc = sender_host_authenticated ? OK : FAIL;
4834 ignore_msg = US"rejected by ACL";
4835 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
4836 &user_msg, &log_msg);
4842 if (authenticated_by == NULL ||
4843 authenticated_by->mail_auth_condition == NULL ||
4844 expand_check_condition(authenticated_by->mail_auth_condition,
4845 authenticated_by->name, US"authenticator"))
4846 break; /* Accept the AUTH */
4848 ignore_msg = US"server_mail_auth_condition failed";
4849 if (authenticated_id != NULL)
4850 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
4851 ignore_msg, authenticated_id);
4856 authenticated_sender = NULL;
4857 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
4858 value, host_and_ident(TRUE), ignore_msg);
4861 /* Should only get DEFER or ERROR here. Put back terminator
4862 overrides for error message */
4867 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
4874 #ifndef DISABLE_PRDR
4875 case ENV_MAIL_OPT_PRDR:
4877 prdr_requested = TRUE;
4882 case ENV_MAIL_OPT_UTF8:
4883 if (!fl.smtputf8_advertised)
4885 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4886 US"SMTPUTF8 used when not advertised");
4890 DEBUG(D_receive) debug_printf("smtputf8 requested\n");
4891 message_smtputf8 = allow_utf8_domains = TRUE;
4892 if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
4894 int old_pool = store_pool;
4895 store_pool = POOL_PERM;
4896 received_protocol = string_sprintf("utf8%s", received_protocol);
4897 store_pool = old_pool;
4902 /* No valid option. Stick back the terminator characters and break
4903 the loop. Do the name-terminator second as extract_option sets
4904 value==name when it found no equal-sign.
4905 An error for a malformed address will occur. */
4906 case ENV_MAIL_OPT_NULL:
4914 /* Break out of for loop if switch() had bad argument or
4915 when start of the email address is reached */
4916 if (arg_error) break;
4919 /* If we have passed the threshold for rate limiting, apply the current
4920 delay, and update it for next time, provided this is a limited host. */
4922 if (smtp_mailcmd_count > smtp_rlm_threshold &&
4923 verify_check_host(&smtp_ratelimit_hosts) == OK)
4925 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
4926 smtp_delay_mail/1000.0);
4927 millisleep((int)smtp_delay_mail);
4928 smtp_delay_mail *= smtp_rlm_factor;
4929 if (smtp_delay_mail > (double)smtp_rlm_limit)
4930 smtp_delay_mail = (double)smtp_rlm_limit;
4933 /* Now extract the address, first applying any SMTP-time rewriting. The
4934 TRUE flag allows "<>" as a sender address. */
4936 raw_sender = rewrite_existflags & rewrite_smtp
4937 /* deconst ok as smtp_cmd_data was not const */
4938 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
4939 global_rewrite_rules)
4943 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
4948 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
4952 sender_address = raw_sender;
4954 /* If there is a configured size limit for mail, check that this message
4955 doesn't exceed it. The check is postponed to this point so that the sender
4958 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
4960 smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
4961 log_write(L_size_reject,
4962 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
4963 "message too big: size%s=%d max=%d",
4965 host_and_ident(TRUE),
4966 (message_size == INT_MAX)? ">" : "",
4968 thismessage_size_limit);
4969 sender_address = NULL;
4973 /* Check there is enough space on the disk unless configured not to.
4974 When smtp_check_spool_space is set, the check is for thismessage_size_limit
4975 plus the current message - i.e. we accept the message only if it won't
4976 reduce the space below the threshold. Add 5000 to the size to allow for
4977 overheads such as the Received: line and storing of recipients, etc.
4978 By putting the check here, even when SIZE is not given, it allow VRFY
4979 and EXPN etc. to be used when space is short. */
4981 if (!receive_check_fs(
4982 smtp_check_spool_space && message_size >= 0
4983 ? message_size + 5000 : 0))
4985 smtp_printf("452 Space shortage, please try later\r\n", FALSE);
4986 sender_address = NULL;
4990 /* If sender_address is unqualified, reject it, unless this is a locally
4991 generated message, or the sending host or net is permitted to send
4992 unqualified addresses - typically local machines behaving as MUAs -
4993 in which case just qualify the address. The flag is set above at the start
4994 of the SMTP connection. */
4996 if (!sender_domain && *sender_address)
4997 if (f.allow_unqualified_sender)
4999 sender_domain = Ustrlen(sender_address) + 1;
5000 /* deconst ok as sender_address was not const */
5001 sender_address = US rewrite_address_qualify(sender_address, FALSE);
5002 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
5007 smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
5009 log_write(L_smtp_syntax_error,
5010 LOG_MAIN|LOG_REJECT,
5011 "unqualified sender rejected: <%s> %s%s",
5013 host_and_ident(TRUE),
5015 sender_address = NULL;
5019 /* Apply an ACL check if one is defined, before responding. Afterwards,
5020 when pipelining is not advertised, do another sync check in case the ACL
5021 delayed and the client started sending in the meantime. */
5025 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
5026 if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
5032 if (rc == OK || rc == DISCARD)
5034 BOOL more = pipeline_response();
5037 smtp_printf("%s%s%s", more, US"250 OK",
5038 #ifndef DISABLE_PRDR
5039 prdr_requested ? US", PRDR Requested" : US"",
5046 #ifndef DISABLE_PRDR
5048 user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
5050 smtp_user_msg(US"250", user_msg);
5052 smtp_delay_rcpt = smtp_rlr_base;
5053 f.recipients_discarded = (rc == DISCARD);
5054 was_rej_mail = FALSE;
5058 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
5059 sender_address = NULL;
5064 /* The RCPT command requires an address as an operand. There may be any
5065 number of RCPT commands, specifying multiple recipients. We build them all
5066 into a data structure. The start/end values given by parse_extract_address
5067 are not used, as we keep only the extracted address. */
5071 /* We got really to many recipients. A check against configured
5072 limits is done later */
5073 if (rcpt_count < 0 || rcpt_count >= INT_MAX/2)
5074 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Too many recipients: %d", rcpt_count);
5076 was_rcpt = fl.rcpt_in_progress = TRUE;
5078 /* There must be a sender address; if the sender was rejected and
5079 pipelining was advertised, we assume the client was pipelining, and do not
5080 count this as a protocol error. Reset was_rej_mail so that further RCPTs
5081 get the same treatment. */
5083 if (sender_address == NULL)
5085 if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
5087 smtp_printf("503 sender not yet given\r\n", FALSE);
5088 was_rej_mail = TRUE;
5092 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5093 US"sender not yet given");
5094 was_rcpt = FALSE; /* Not a valid RCPT */
5100 /* Check for an operand */
5102 if (smtp_cmd_data[0] == 0)
5104 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5105 US"RCPT must have an address operand");
5110 /* Set the DSN flags orcpt and dsn_flags from the session*/
5114 if (fl.esmtp) for(;;)
5116 uschar *name, *value;
5118 if (!extract_option(&name, &value))
5121 if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
5123 /* Check whether orcpt has been already set */
5126 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5127 US"ORCPT can be specified once only");
5130 orcpt = string_copy(value);
5131 DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
5134 else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
5136 /* Check if the notify flags have been already set */
5139 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5140 US"NOTIFY can be specified once only");
5143 if (strcmpic(value, US"NEVER") == 0)
5144 dsn_flags |= rf_notify_never;
5151 while (*pp != 0 && *pp != ',') pp++;
5152 if (*pp == ',') *pp++ = 0;
5153 if (strcmpic(p, US"SUCCESS") == 0)
5155 DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
5156 dsn_flags |= rf_notify_success;
5158 else if (strcmpic(p, US"FAILURE") == 0)
5160 DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
5161 dsn_flags |= rf_notify_failure;
5163 else if (strcmpic(p, US"DELAY") == 0)
5165 DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
5166 dsn_flags |= rf_notify_delay;
5170 /* Catch any strange values */
5171 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5172 US"Invalid value for NOTIFY parameter");
5177 DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
5181 /* Unknown option. Stick back the terminator characters and break
5182 the loop. An error for a malformed address will occur. */
5186 DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
5193 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
5194 as a recipient address */
5196 recipient = rewrite_existflags & rewrite_smtp
5197 /* deconst ok as smtp_cmd_data was not const */
5198 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
5199 global_rewrite_rules)
5202 if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
5203 &recipient_domain, FALSE)))
5205 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
5210 /* If the recipient address is unqualified, reject it, unless this is a
5211 locally generated message. However, unqualified addresses are permitted
5212 from a configured list of hosts and nets - typically when behaving as
5213 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
5214 really. The flag is set at the start of the SMTP connection.
5216 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
5217 assumed this meant "reserved local part", but the revision of RFC 821 and
5218 friends now makes it absolutely clear that it means *mailbox*. Consequently
5219 we must always qualify this address, regardless. */
5221 if (!recipient_domain)
5222 if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
5229 /* Check maximum allowed */
5231 if (rcpt_count+1 < 0 || rcpt_count > recipients_max && recipients_max > 0)
5233 if (recipients_max_reject)
5236 smtp_printf("552 too many recipients\r\n", FALSE);
5238 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
5239 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
5244 smtp_printf("452 too many recipients\r\n", FALSE);
5246 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
5247 "temporarily rejected: sender=<%s> %s", sender_address,
5248 host_and_ident(TRUE));
5255 /* If we have passed the threshold for rate limiting, apply the current
5256 delay, and update it for next time, provided this is a limited host. */
5258 if (rcpt_count > smtp_rlr_threshold &&
5259 verify_check_host(&smtp_ratelimit_hosts) == OK)
5261 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
5262 smtp_delay_rcpt/1000.0);
5263 millisleep((int)smtp_delay_rcpt);
5264 smtp_delay_rcpt *= smtp_rlr_factor;
5265 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
5266 smtp_delay_rcpt = (double)smtp_rlr_limit;
5269 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
5270 for them. Otherwise, check the access control list for this recipient. As
5271 there may be a delay in this, re-check for a synchronization error
5272 afterwards, unless pipelining was advertised. */
5274 if (f.recipients_discarded)
5277 if ( (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
5279 && !f.smtp_in_pipelining_advertised && !check_sync())
5282 /* The ACL was happy */
5286 BOOL more = pipeline_response();
5289 smtp_user_msg(US"250", user_msg);
5291 smtp_printf("250 Accepted\r\n", more);
5292 receive_add_recipient(recipient, -1);
5294 /* Set the dsn flags in the recipients_list */
5295 recipients_list[recipients_count-1].orcpt = orcpt;
5296 recipients_list[recipients_count-1].dsn_flags = dsn_flags;
5298 /* DEBUG(D_receive) debug_printf("DSN: orcpt: %s flags: %d\n",
5299 recipients_list[recipients_count-1].orcpt,
5300 recipients_list[recipients_count-1].dsn_flags); */
5303 /* The recipient was discarded */
5305 else if (rc == DISCARD)
5308 smtp_user_msg(US"250", user_msg);
5310 smtp_printf("250 Accepted\r\n", FALSE);
5313 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
5314 "discarded by %s ACL%s%s", host_and_ident(TRUE),
5315 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
5316 smtp_cmd_argument, f.recipients_discarded ? "MAIL" : "RCPT",
5317 log_msg ? US": " : US"", log_msg ? log_msg : US"");
5320 /* Either the ACL failed the address, or it was deferred. */
5324 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
5325 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
5330 /* The DATA command is legal only if it follows successful MAIL FROM
5331 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
5332 not counted as a protocol error if it follows RCPT (which must have been
5333 rejected if there are no recipients.) This function is complete when a
5334 valid DATA command is encountered.
5336 Note concerning the code used: RFC 2821 says this:
5338 - If there was no MAIL, or no RCPT, command, or all such commands
5339 were rejected, the server MAY return a "command out of sequence"
5340 (503) or "no valid recipients" (554) reply in response to the
5343 The example in the pipelining RFC 2920 uses 554, but I use 503 here
5344 because it is the same whether pipelining is in use or not.
5346 If all the RCPT commands that precede DATA provoked the same error message
5347 (often indicating some kind of system error), it is helpful to include it
5348 with the DATA rejection (an idea suggested by Tony Finch). */
5355 if (chunking_state != CHUNKING_OFFERED)
5357 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5358 US"BDAT command used when CHUNKING not advertised");
5362 /* grab size, endmarker */
5364 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
5366 done = synprot_error(L_smtp_protocol_error, 501, NULL,
5367 US"missing size for BDAT command");
5370 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
5371 ? CHUNKING_LAST : CHUNKING_ACTIVE;
5372 chunking_data_left = chunking_datasize;
5373 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
5374 (int)chunking_state, chunking_data_left);
5376 f.bdat_readers_wanted = TRUE; /* FIXME: redundant vs chunking_state? */
5385 f.bdat_readers_wanted = FALSE;
5387 DATA_BDAT: /* Common code for DATA and BDAT */
5388 #ifndef DISABLE_PIPE_CONNECT
5389 fl.pipe_connect_acceptable = FALSE;
5391 if (!discarded && recipients_count <= 0)
5393 if (fl.rcpt_smtp_response_same && rcpt_smtp_response != NULL)
5395 uschar *code = US"503";
5396 int len = Ustrlen(rcpt_smtp_response);
5397 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
5399 /* Responses from smtp_printf() will have \r\n on the end */
5400 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
5401 rcpt_smtp_response[len-2] = 0;
5402 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
5404 if (f.smtp_in_pipelining_advertised && last_was_rcpt)
5405 smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
5406 smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]);
5408 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5409 smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA
5410 ? US"valid RCPT command must precede DATA"
5411 : US"valid RCPT command must precede BDAT");
5413 if (chunking_state > CHUNKING_OFFERED)
5415 bdat_push_receive_functions();
5421 if (toomany && recipients_max_reject)
5423 sender_address = NULL; /* This will allow a new MAIL without RSET */
5424 sender_address_unrewritten = NULL;
5425 smtp_printf("554 Too many recipients\r\n", FALSE);
5427 if (chunking_state > CHUNKING_OFFERED)
5429 bdat_push_receive_functions();
5435 if (chunking_state > CHUNKING_OFFERED)
5436 rc = OK; /* No predata ACL or go-ahead output for BDAT */
5439 /* If there is an ACL, re-check the synchronization afterwards, since the
5440 ACL may have delayed. To handle cutthrough delivery enforce a dummy call
5441 to get the DATA command sent. */
5443 if (acl_smtp_predata == NULL && cutthrough.cctx.sock < 0)
5447 uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
5448 f.enable_dollar_recipients = TRUE;
5449 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
5451 f.enable_dollar_recipients = FALSE;
5452 if (rc == OK && !check_sync())
5456 { /* Either the ACL failed the address, or it was deferred. */
5457 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
5463 smtp_user_msg(US"354", user_msg);
5466 "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
5469 if (f.bdat_readers_wanted)
5470 bdat_push_receive_functions();
5473 if (smtp_in) /* all ACKs needed to ramp window up for bulk data */
5474 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
5475 US &on, sizeof(on));
5478 message_ended = END_NOTENDED; /* Indicate in middle of data */
5489 if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
5490 &start, &end, &recipient_domain, FALSE)))
5492 smtp_printf("501 %s\r\n", FALSE, errmess);
5496 if (!recipient_domain)
5497 if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
5501 if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
5502 &user_msg, &log_msg)) != OK)
5503 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
5507 address_item * addr = deliver_make_addr(address, FALSE);
5509 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
5510 -1, -1, NULL, NULL, NULL))
5513 s = string_sprintf("250 <%s> is deliverable", address);
5517 s = (addr->user_message != NULL)?
5518 string_sprintf("451 <%s> %s", address, addr->user_message) :
5519 string_sprintf("451 Cannot resolve <%s> at this time", address);
5523 s = (addr->user_message != NULL)?
5524 string_sprintf("550 <%s> %s", address, addr->user_message) :
5525 string_sprintf("550 <%s> is not deliverable", address);
5526 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
5527 smtp_cmd_argument, host_and_ident(TRUE));
5531 smtp_printf("%s\r\n", FALSE, s);
5539 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
5541 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
5544 BOOL save_log_testing_mode = f.log_testing_mode;
5545 f.address_test_mode = f.log_testing_mode = TRUE;
5546 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
5547 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
5549 f.address_test_mode = FALSE;
5550 f.log_testing_mode = save_log_testing_mode; /* true for -bh */
5559 if (!fl.tls_advertised)
5561 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5562 US"STARTTLS command used when not advertised");
5566 /* Apply an ACL check if one is defined */
5568 if ( acl_smtp_starttls
5569 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
5570 &user_msg, &log_msg)) != OK
5573 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
5577 /* RFC 2487 is not clear on when this command may be sent, though it
5578 does state that all information previously obtained from the client
5579 must be discarded if a TLS session is started. It seems reasonable to
5580 do an implied RSET when STARTTLS is received. */
5582 incomplete_transaction_log(US"STARTTLS");
5583 cancel_cutthrough_connection(TRUE, US"STARTTLS received");
5584 reset_point = smtp_reset(reset_point);
5586 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
5588 /* There's an attack where more data is read in past the STARTTLS command
5589 before TLS is negotiated, then assumed to be part of the secure session
5590 when used afterwards; we use segregated input buffers, so are not
5591 vulnerable, but we want to note when it happens and, for sheer paranoia,
5592 ensure that the buffer is "wiped".
5593 Pipelining sync checks will normally have protected us too, unless disabled
5594 by configuration. */
5599 debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
5600 if (tls_in.active.sock < 0)
5601 smtp_inend = smtp_inptr = smtp_inbuffer;
5602 /* and if TLS is already active, tls_server_start() should fail */
5605 /* There is nothing we value in the input buffer and if TLS is successfully
5606 negotiated, we won't use this buffer again; if TLS fails, we'll just read
5607 fresh content into it. The buffer contains arbitrary content from an
5608 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
5609 It seems safest to just wipe away the content rather than leave it as a
5610 target to jump to. */
5612 memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);
5614 /* Attempt to start up a TLS session, and if successful, discard all
5615 knowledge that was obtained previously. At least, that's what the RFC says,
5616 and that's what happens by default. However, in order to work round YAEB,
5617 there is an option to remember the esmtp state. Sigh.
5619 We must allow for an extra EHLO command and an extra AUTH command after
5620 STARTTLS that don't add to the nonmail command count. */
5623 if ((rc = tls_server_start(&s)) == OK)
5625 if (!tls_remember_esmtp)
5626 fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
5627 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
5628 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
5629 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
5630 if (sender_helo_name)
5632 sender_helo_name = NULL;
5633 host_build_sender_fullhost(); /* Rebuild */
5634 set_process_info("handling incoming TLS connection from %s",
5635 host_and_ident(FALSE));
5638 (sender_host_address ? protocols : protocols_local)
5640 ? pextend + (sender_host_authenticated ? pauthed : 0)
5642 + (tls_in.active.sock >= 0 ? pcrpted : 0)
5645 sender_host_auth_pubname = sender_host_authenticated = NULL;
5646 authenticated_id = NULL;
5647 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
5648 DEBUG(D_tls) debug_printf("TLS active\n");
5649 break; /* Successful STARTTLS */
5652 (void) smtp_log_tls_fail(s);
5654 /* Some local configuration problem was discovered before actually trying
5655 to do a TLS handshake; give a temporary error. */
5659 smtp_printf("454 TLS currently unavailable\r\n", FALSE);
5663 /* Hard failure. Reject everything except QUIT or closed connection. One
5664 cause for failure is a nested STARTTLS, in which case tls_in.active remains
5665 set, but we must still reject all incoming commands. Another is a handshake
5666 failure - and there may some encrypted data still in the pipe to us, which we
5667 see as garbage commands. */
5669 DEBUG(D_tls) debug_printf("TLS failed to start\n");
5670 while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
5673 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
5674 smtp_get_connection_info());
5675 smtp_notquit_exit(US"tls-failed", NULL, NULL);
5679 /* It is perhaps arguable as to which exit ACL should be called here,
5680 but as it is probably a situation that almost never arises, it
5681 probably doesn't matter. We choose to call the real QUIT ACL, which in
5682 some sense is perhaps "right". */
5685 f.smtp_in_quit = TRUE;
5688 && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
5689 &log_msg)) == ERROR))
5690 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
5693 smtp_respond(US"221", 3, TRUE, user_msg);
5695 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
5696 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
5697 smtp_get_connection_info());
5702 smtp_printf("554 Security failure\r\n", FALSE);
5705 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
5710 /* The ACL for QUIT is provided for gathering statistical information or
5711 similar; it does not affect the response code, but it can supply a custom
5715 smtp_quit_handler(&user_msg, &log_msg);
5721 smtp_rset_handler();
5722 cancel_cutthrough_connection(TRUE, US"RSET received");
5723 reset_point = smtp_reset(reset_point);
5730 smtp_printf("250 OK\r\n", FALSE);
5734 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
5735 used, a check will be done for permitted hosts. Show STARTTLS only if not
5736 already in a TLS session and if it would be advertised in the EHLO
5741 smtp_printf("214-Commands supported:\r\n", TRUE);
5745 Ustrcat(buffer, US" AUTH");
5747 if (tls_in.active.sock < 0 &&
5748 verify_check_host(&tls_advertise_hosts) != FAIL)
5749 Ustrcat(buffer, US" STARTTLS");
5751 Ustrcat(buffer, US" HELO EHLO MAIL RCPT DATA BDAT");
5752 Ustrcat(buffer, US" NOOP QUIT RSET HELP");
5753 if (acl_smtp_etrn) Ustrcat(buffer, US" ETRN");
5754 if (acl_smtp_expn) Ustrcat(buffer, US" EXPN");
5755 if (acl_smtp_vrfy) Ustrcat(buffer, US" VRFY");
5756 smtp_printf("214%s\r\n", FALSE, buffer);
5762 incomplete_transaction_log(US"connection lost");
5763 smtp_notquit_exit(US"connection-lost", US"421",
5764 US"%s lost input connection", smtp_active_hostname);
5766 /* Don't log by default unless in the middle of a message, as some mailers
5767 just drop the call rather than sending QUIT, and it clutters up the logs.
5770 if (sender_address || recipients_count > 0)
5771 log_write(L_lost_incoming_connection, LOG_MAIN,
5772 "unexpected %s while reading SMTP command from %s%s%s D=%s",
5773 f.sender_host_unknown ? "EOF" : "disconnection",
5774 f.tcp_in_fastopen_logged
5777 ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
5779 host_and_ident(FALSE), smtp_read_error,
5780 string_timesince(&smtp_connection_start)
5784 log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
5785 smtp_get_connection_info(),
5786 f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
5788 string_timesince(&smtp_connection_start)
5799 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5800 US"ETRN is not permitted inside a transaction");
5804 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
5805 host_and_ident(FALSE));
5807 if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
5808 &user_msg, &log_msg)) != OK)
5810 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
5814 /* Compute the serialization key for this command. */
5816 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
5818 /* If a command has been specified for running as a result of ETRN, we
5819 permit any argument to ETRN. If not, only the # standard form is permitted,
5820 since that is strictly the only kind of ETRN that can be implemented
5821 according to the RFC. */
5823 if (smtp_etrn_command)
5827 etrn_command = smtp_etrn_command;
5828 deliver_domain = smtp_cmd_data;
5829 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
5830 US"ETRN processing", &error);
5831 deliver_domain = NULL;
5834 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
5836 smtp_printf("458 Internal failure\r\n", FALSE);
5841 /* Else set up to call Exim with the -R option. */
5845 if (*smtp_cmd_data++ != '#')
5847 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5848 US"argument must begin with #");
5851 etrn_command = US"exim -R";
5852 argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
5853 *queue_name ? 4 : 2,
5854 US"-R", smtp_cmd_data,
5855 US"-MCG", queue_name);
5858 /* If we are host-testing, don't actually do anything. */
5864 debug_printf("ETRN command is: %s\n", etrn_command);
5865 debug_printf("ETRN command execution skipped\n");
5867 if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
5868 else smtp_user_msg(US"250", user_msg);
5873 /* If ETRN queue runs are to be serialized, check the database to
5874 ensure one isn't already running. */
5876 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
5878 smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
5882 /* Fork a child process and run the command. We don't want to have to
5883 wait for the process at any point, so set SIGCHLD to SIG_IGN before
5884 forking. It should be set that way anyway for external incoming SMTP,
5885 but we save and restore to be tidy. If serialization is required, we
5886 actually run the command in yet another process, so we can wait for it
5887 to complete and then remove the serialization lock. */
5889 oldsignal = signal(SIGCHLD, SIG_IGN);
5891 if ((pid = exim_fork(US"etrn-command")) == 0)
5893 smtp_input = FALSE; /* This process is not associated with the */
5894 (void)fclose(smtp_in); /* SMTP call any more. */
5895 (void)fclose(smtp_out);
5897 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
5899 /* If not serializing, do the exec right away. Otherwise, fork down
5900 into another process. */
5902 if ( !smtp_etrn_serialize
5903 || (pid = exim_fork(US"etrn-serialised-command")) == 0)
5905 DEBUG(D_exec) debug_print_argv(argv);
5906 exim_nullstd(); /* Ensure std{in,out,err} exist */
5907 execv(CS argv[0], (char *const *)argv);
5908 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
5909 etrn_command, strerror(errno));
5910 _exit(EXIT_FAILURE); /* paranoia */
5913 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
5914 is, we are in the first subprocess, after forking again. All we can do
5915 for a failing fork is to log it. Otherwise, wait for the 2nd process to
5916 complete, before removing the serialization. */
5919 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
5920 "failed: %s", strerror(errno));
5924 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
5926 (void)wait(&status);
5927 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
5931 enq_end(etrn_serialize_key);
5932 exim_underbar_exit(EXIT_SUCCESS);
5935 /* Back in the top level SMTP process. Check that we started a subprocess
5936 and restore the signal state. */
5940 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
5942 smtp_printf("458 Unable to fork process\r\n", FALSE);
5943 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
5947 smtp_printf("250 OK\r\n", FALSE);
5949 smtp_user_msg(US"250", user_msg);
5951 signal(SIGCHLD, oldsignal);
5956 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5957 US"unexpected argument data");
5961 /* This currently happens only for NULLs, but could be extended. */
5964 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
5965 US"NUL character(s) present (shown as '?')");
5966 smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
5973 if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
5974 smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
5975 c = smtp_inend - smtp_inptr;
5976 if (c > 150) c = 150; /* limit logged amount */
5978 incomplete_transaction_log(US"sync failure");
5979 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
5980 "(next input sent too soon: pipelining was%s advertised): "
5981 "rejected \"%s\" %s next input=\"%s\"",
5982 f.smtp_in_pipelining_advertised ? "" : " not",
5983 smtp_cmd_buffer, host_and_ident(TRUE),
5984 string_printing(smtp_inptr));
5985 smtp_notquit_exit(US"synchronization-error", US"554",
5986 US"SMTP synchronization error");
5987 done = 1; /* Pretend eof - drops connection */
5991 case TOO_MANY_NONMAIL_CMD:
5992 s = smtp_cmd_buffer;
5993 while (*s != 0 && !isspace(*s)) s++;
5994 incomplete_transaction_log(US"too many non-mail commands");
5995 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
5996 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
5997 (int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
5998 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
5999 done = 1; /* Pretend eof - drops connection */
6002 #ifdef SUPPORT_PROXY
6003 case PROXY_FAIL_IGNORE_CMD:
6004 smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
6009 if (unknown_command_count++ >= smtp_max_unknown_commands)
6011 log_write(L_smtp_syntax_error, LOG_MAIN,
6012 "SMTP syntax error in \"%s\" %s %s",
6013 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
6014 US"unrecognized command");
6015 incomplete_transaction_log(US"unrecognized command");
6016 smtp_notquit_exit(US"bad-commands", US"500",
6017 US"Too many unrecognized commands");
6019 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
6020 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
6021 string_printing(smtp_cmd_buffer));
6024 done = synprot_error(L_smtp_syntax_error, 500, NULL,
6025 US"unrecognized command");
6029 /* This label is used by goto's inside loops that want to break out to
6030 the end of the command-processing loop. */
6033 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
6034 last_was_rcpt = was_rcpt; /* protocol error handling */
6038 return done - 2; /* Convert yield values */
6044 authres_smtpauth(gstring * g)
6046 if (!sender_host_authenticated)
6049 g = string_append(g, 2, US";\n\tauth=pass (", sender_host_auth_pubname);
6051 if (Ustrcmp(sender_host_auth_pubname, "tls") == 0)
6052 g = authenticated_id
6053 ? string_append(g, 2, US") x509.auth=", authenticated_id)
6054 : string_cat(g, US") reason=x509.auth");
6056 g = authenticated_id
6057 ? string_append(g, 2, US") smtp.auth=", authenticated_id)
6058 : string_cat(g, US", no id saved)");
6060 if (authenticated_sender)
6061 g = string_append(g, 2, US" smtp.mailfrom=", authenticated_sender);
6069 /* End of smtp_in.c */