1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
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 * Recheck synchronization *
324 *************************************************/
326 /* Synchronization checks can never be perfect because a packet may be on its
327 way but not arrived when the check is done. Normally, the checks happen when
328 commands are read: Exim ensures that there is no more input in the input buffer.
329 In normal cases, the response to the command will be fast, and there is no
332 However, for some commands an ACL is run, and that can include delays. In those
333 cases, it is useful to do another check on the input just before sending the
334 response. This also applies at the start of a connection. This function does
335 that check by means of the select() function, as long as the facility is not
336 disabled or inappropriate. A failure of select() is ignored.
338 When there is unwanted input, we read it so that it appears in the log of the
342 Returns: TRUE if all is well; FALSE if there is input pending
346 wouldblock_reading(void)
350 struct timeval tzero = {.tv_sec = 0, .tv_usec = 0};
353 if (tls_in.active.sock >= 0)
354 return !tls_could_read();
357 if (smtp_inptr < smtp_inend)
360 fd = fileno(smtp_in);
363 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
365 if (rc <= 0) return TRUE; /* Not ready to read */
366 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
367 if (rc < 0) return TRUE; /* End of file or error */
376 if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
379 return wouldblock_reading();
383 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
384 a reponse with the one following. */
387 pipeline_response(void)
389 if ( !smtp_enforce_sync || !sender_host_address
390 || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
393 if (wouldblock_reading()) return FALSE;
394 f.smtp_in_pipelining_used = TRUE;
399 #ifndef DISABLE_PIPE_CONNECT
401 pipeline_connect_sends(void)
403 if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
406 if (wouldblock_reading()) return FALSE;
407 f.smtp_in_early_pipe_used = TRUE;
412 /*************************************************
413 * Log incomplete transactions *
414 *************************************************/
416 /* This function is called after a transaction has been aborted by RSET, QUIT,
417 connection drops or other errors. It logs the envelope information received
418 so far in order to preserve address verification attempts.
420 Argument: string to indicate what aborted the transaction
425 incomplete_transaction_log(uschar *what)
427 if (!sender_address /* No transaction in progress */
428 || !LOGGING(smtp_incomplete_transaction))
431 /* Build list of recipients for logging */
433 if (recipients_count > 0)
435 raw_recipients = store_get(recipients_count * sizeof(uschar *), FALSE);
436 for (int i = 0; i < recipients_count; i++)
437 raw_recipients[i] = recipients_list[i].address;
438 raw_recipients_count = recipients_count;
441 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
442 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
449 smtp_command_timeout_exit(void)
451 log_write(L_lost_incoming_connection,
452 LOG_MAIN, "SMTP command timeout on%s connection from %s",
453 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
454 if (smtp_batched_input)
455 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
456 smtp_notquit_exit(US"command-timeout", US"421",
457 US"%s: SMTP command timeout - closing connection",
458 smtp_active_hostname);
459 exim_exit(EXIT_FAILURE);
463 smtp_command_sigterm_exit(void)
465 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
466 if (smtp_batched_input)
467 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
468 smtp_notquit_exit(US"signal-exit", US"421",
469 US"%s: Service not available - closing connection", smtp_active_hostname);
470 exim_exit(EXIT_FAILURE);
474 smtp_data_timeout_exit(void)
476 log_write(L_lost_incoming_connection,
477 LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
478 sender_fullhost ? sender_fullhost : US"local process", sender_address);
479 receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
480 /* Does not return */
484 smtp_data_sigint_exit(void)
486 log_write(0, LOG_MAIN, "%s closed after %s",
487 smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
488 receive_bomb_out(US"signal-exit",
489 US"Service not available - SIGTERM or SIGINT received");
490 /* Does not return */
495 /* Refill the buffer, and notify DKIM verification code.
496 Return false for error or EOF.
500 smtp_refill(unsigned lim)
503 if (!smtp_out) return FALSE;
505 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
507 /* Limit amount read, so non-message data is not fed to DKIM.
508 Take care to not touch the safety NUL at the end of the buffer. */
510 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
512 if (smtp_receive_timeout > 0) ALARM_CLR(0);
515 /* Must put the error text in fixed store, because this might be during
516 header reading, where it releases unused store above the header. */
519 if (had_command_timeout) /* set by signal handler */
520 smtp_command_timeout_exit(); /* does not return */
521 if (had_command_sigterm)
522 smtp_command_sigterm_exit();
523 if (had_data_timeout)
524 smtp_data_timeout_exit();
526 smtp_data_sigint_exit();
528 smtp_had_error = save_errno;
529 smtp_read_error = string_copy_perm(
530 string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
537 dkim_exim_verify_feed(smtp_inbuffer, rc);
539 smtp_inend = smtp_inbuffer + rc;
540 smtp_inptr = smtp_inbuffer;
544 /*************************************************
545 * SMTP version of getc() *
546 *************************************************/
548 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
549 it flushes the output, and refills the buffer, with a timeout. The signal
550 handler is set appropriately by the calling function. This function is not used
551 after a connection has negotiated itself into an TLS/SSL state.
553 Arguments: lim Maximum amount to read/buffer
554 Returns: the next character or EOF
558 smtp_getc(unsigned lim)
560 if (smtp_inptr >= smtp_inend)
561 if (!smtp_refill(lim))
563 return *smtp_inptr++;
567 smtp_getbuf(unsigned * len)
572 if (smtp_inptr >= smtp_inend)
573 if (!smtp_refill(*len))
574 { *len = 0; return NULL; }
576 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
587 int n = smtp_inend - smtp_inptr;
588 if (chunking_state == CHUNKING_LAST && chunking_data_left < n)
589 n = chunking_data_left;
591 dkim_exim_verify_feed(smtp_inptr, n);
596 /* Forward declarations */
597 static inline void bdat_push_receive_functions(void);
598 static inline void bdat_pop_receive_functions(void);
601 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
602 previous BDAT chunk and getting new ones when we run out. Uses the
603 underlying smtp_getc or tls_getc both for that and for getting the
604 (buffered) data byte. EOD signals (an expected) no further data.
605 ERR signals a protocol error, and EOF a closed input stream.
607 Called from read_bdat_smtp() in receive.c for the message body, but also
608 by the headers read loop in receive_msg(); manipulates chunking_state
609 to handle the BDAT command/response.
610 Placed here due to the correlation with the above smtp_getc(), which it wraps,
611 and also by the need to do smtp command/response handling.
613 Arguments: lim (ignored)
614 Returns: the next character or ERR, EOD or EOF
618 bdat_getc(unsigned lim)
620 uschar * user_msg = NULL;
629 if (chunking_data_left > 0)
630 return lwr_receive_getc(chunking_data_left--);
632 bdat_pop_receive_functions();
634 dkim_save = dkim_collect_input;
635 dkim_collect_input = 0;
638 /* Unless PIPELINING was offered, there should be no next command
639 until after we ack that chunk */
641 if (!f.smtp_in_pipelining_advertised && !check_sync())
643 unsigned n = smtp_inend - smtp_inptr;
646 incomplete_transaction_log(US"sync failure");
647 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
648 "(next input sent too soon: pipelining was not advertised): "
649 "rejected \"%s\" %s next input=\"%s\"%s",
650 smtp_cmd_buffer, host_and_ident(TRUE),
651 string_printing(string_copyn(smtp_inptr, n)),
652 smtp_inend - smtp_inptr > n ? "..." : "");
653 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
654 US"SMTP synchronization error");
655 goto repeat_until_rset;
658 /* If not the last, ack the received chunk. The last response is delayed
659 until after the data ACL decides on it */
661 if (chunking_state == CHUNKING_LAST)
664 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
669 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
670 chunking_state = CHUNKING_OFFERED;
671 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
673 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
674 QUIT, RSET or NOOP but handling them seems obvious */
677 switch(smtp_read_command(TRUE, 1))
680 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
681 US"only BDAT permissible after non-LAST BDAT");
684 switch(smtp_read_command(TRUE, 1))
686 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
687 case EOF_CMD: return EOF;
688 case RSET_CMD: smtp_rset_handler(); return ERR;
689 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
690 US"only RSET accepted now") > 0)
692 goto repeat_until_rset;
696 smtp_quit_handler(&user_msg, &log_msg);
707 smtp_printf("250 OK\r\n", FALSE);
714 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
716 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
717 US"missing size for BDAT command");
720 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
721 ? CHUNKING_LAST : CHUNKING_ACTIVE;
722 chunking_data_left = chunking_datasize;
723 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
724 (int)chunking_state, chunking_data_left);
726 if (chunking_datasize == 0)
727 if (chunking_state == CHUNKING_LAST)
731 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
732 US"zero size for BDAT command");
733 goto repeat_until_rset;
736 bdat_push_receive_functions();
738 dkim_collect_input = dkim_save;
740 break; /* to top of main loop */
747 bdat_getbuf(unsigned * len)
751 if (chunking_data_left <= 0)
752 { *len = 0; return NULL; }
754 if (*len > chunking_data_left) *len = chunking_data_left;
755 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
756 chunking_data_left -= *len;
761 bdat_flush_data(void)
763 while (chunking_data_left)
765 unsigned n = chunking_data_left;
766 if (!bdat_getbuf(&n)) break;
769 bdat_pop_receive_functions();
771 if (chunking_state != CHUNKING_LAST)
773 chunking_state = CHUNKING_OFFERED;
774 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
780 bdat_push_receive_functions(void)
782 /* push the current receive_* function on the "stack", and
783 replace them by bdat_getc(), which in turn will use the lwr_receive_*
784 functions to do the dirty work. */
785 if (lwr_receive_getc == NULL)
787 lwr_receive_getc = receive_getc;
788 lwr_receive_getbuf = receive_getbuf;
789 lwr_receive_ungetc = receive_ungetc;
793 DEBUG(D_receive) debug_printf("chunking double-push receive functions\n");
796 receive_getc = bdat_getc;
797 receive_getbuf = bdat_getbuf;
798 receive_ungetc = bdat_ungetc;
802 bdat_pop_receive_functions(void)
804 if (lwr_receive_getc == NULL)
806 DEBUG(D_receive) debug_printf("chunking double-pop receive functions\n");
809 receive_getc = lwr_receive_getc;
810 receive_getbuf = lwr_receive_getbuf;
811 receive_ungetc = lwr_receive_ungetc;
813 lwr_receive_getc = NULL;
814 lwr_receive_getbuf = NULL;
815 lwr_receive_ungetc = NULL;
818 /*************************************************
819 * SMTP version of ungetc() *
820 *************************************************/
822 /* Puts a character back in the input buffer. Only ever
828 Returns: the character
834 if (smtp_inptr <= smtp_inbuffer)
835 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in smtp_ungetc");
845 chunking_data_left++;
846 bdat_push_receive_functions(); /* we're not done yet, calling push is safe, because it checks the state before pushing anything */
847 return lwr_receive_ungetc(ch);
852 /*************************************************
853 * SMTP version of feof() *
854 *************************************************/
856 /* Tests for a previous EOF
859 Returns: non-zero if the eof flag is set
871 /*************************************************
872 * SMTP version of ferror() *
873 *************************************************/
875 /* Tests for a previous read error, and returns with errno
876 restored to what it was when the error was detected.
879 Returns: non-zero if the error flag is set
885 errno = smtp_had_error;
886 return smtp_had_error;
891 /*************************************************
892 * Test for characters in the SMTP buffer *
893 *************************************************/
895 /* Used at the end of a message
904 return smtp_inptr < smtp_inend;
909 /*************************************************
910 * Write formatted string to SMTP channel *
911 *************************************************/
913 /* This is a separate function so that we don't have to repeat everything for
914 TLS support or debugging. It is global so that the daemon and the
915 authentication functions can use it. It does not return any error indication,
916 because major problems such as dropped connections won't show up till an output
917 flush for non-TLS connections. The smtp_fflush() function is available for
918 checking that: for convenience, TLS output errors are remembered here so that
919 they are also picked up later by smtp_fflush().
921 This function is exposed to the local_scan API; do not change the signature.
925 more further data expected
926 ... optional arguments
932 smtp_printf(const char *format, BOOL more, ...)
937 smtp_vprintf(format, more, ap);
941 /* This is split off so that verify.c:respond_printf() can, in effect, call
942 smtp_printf(), bearing in mind that in C a vararg function can't directly
943 call another vararg function, only a function which accepts a va_list.
945 This function is exposed to the local_scan API; do not change the signature.
947 /*XXX consider passing caller-info in, for string_vformat-onward */
950 smtp_vprintf(const char *format, BOOL more, va_list ap)
952 gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
955 /* Use taint-unchecked routines for writing into big_buffer, trusting
956 that we'll never expand it. */
958 yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
959 string_from_gstring(&gs);
963 uschar *msg_copy, *cr, *end;
964 msg_copy = string_copy(gs.s);
965 end = msg_copy + gs.ptr;
966 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
967 memmove(cr, cr + 1, (end--) - cr);
968 debug_printf("SMTP>> %s", msg_copy);
973 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
974 smtp_closedown(US"Unexpected error");
975 exim_exit(EXIT_FAILURE);
978 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
979 have had the same. Note: this code is also present in smtp_respond(). It would
980 be tidier to have it only in one place, but when it was added, it was easier to
981 do it that way, so as not to have to mess with the code for the RCPT command,
982 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
984 if (fl.rcpt_in_progress)
986 if (rcpt_smtp_response == NULL)
987 rcpt_smtp_response = string_copy(big_buffer);
988 else if (fl.rcpt_smtp_response_same &&
989 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
990 fl.rcpt_smtp_response_same = FALSE;
991 fl.rcpt_in_progress = FALSE;
994 /* Now write the string */
998 tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
1000 (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
1002 smtp_write_error = -1;
1007 /*************************************************
1008 * Flush SMTP out and check for error *
1009 *************************************************/
1011 /* This function isn't currently used within Exim (it detects errors when it
1012 tries to read the next SMTP input), but is available for use in local_scan().
1013 It flushes the output and checks for errors.
1016 Returns: 0 for no error; -1 after an error
1022 if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
1026 tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
1028 (fflush(smtp_out) != 0)
1030 smtp_write_error = -1;
1032 return smtp_write_error;
1037 /*************************************************
1038 * SMTP command read timeout *
1039 *************************************************/
1041 /* Signal handler for timing out incoming SMTP commands. This attempts to
1044 Argument: signal number (SIGALRM)
1049 command_timeout_handler(int sig)
1051 had_command_timeout = sig;
1056 /*************************************************
1057 * SIGTERM received *
1058 *************************************************/
1060 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
1062 Argument: signal number (SIGTERM)
1067 command_sigterm_handler(int sig)
1069 had_command_sigterm = sig;
1075 #ifdef SUPPORT_PROXY
1076 /*************************************************
1077 * Check if host is required proxy host *
1078 *************************************************/
1079 /* The function determines if inbound host will be a regular smtp host
1080 or if it is configured that it must use Proxy Protocol. A local
1088 check_proxy_protocol_host()
1092 if ( sender_host_address
1093 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
1094 sender_host_address, NULL)) == OK)
1097 debug_printf("Detected proxy protocol configured host\n");
1098 proxy_session = TRUE;
1100 return proxy_session;
1104 /*************************************************
1105 * Read data until newline or end of buffer *
1106 *************************************************/
1107 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1108 read an entire buffer and assume there will be nothing past a proxy protocol
1109 header. Our approach normally is to use stdio, but again that relies upon
1110 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1111 reading _nothing_ before client TLS handshake. So we don't want to use the
1112 usual buffering reads which may read enough to block TLS starting.
1114 So unfortunately we're down to "read one byte at a time, with a syscall each,
1115 and expect a little overhead", for all proxy-opened connections which are v1,
1116 just to handle the TLS-on-connect case. Since SSL functions wrap the
1117 underlying fd, we can't assume that we can feed them any already-read content.
1119 We need to know where to read to, the max capacity, and we'll read until we
1120 get a CR and one more character. Let the caller scream if it's CR+!LF.
1122 Return the amount read.
1126 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1128 uschar *to = base + already;
1134 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1135 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1137 cr = memchr(base, '\r', already);
1140 if ((cr - base) < already - 1)
1142 /* \r and presumed \n already within what we have; probably not
1143 actually proxy protocol, but abort cleanly. */
1146 /* \r is last character read, just need one more. */
1150 while (capacity > 0)
1152 do { ret = read(fd, to, 1); } while (ret == -1 && errno == EINTR && !had_command_timeout);
1164 /* reached end without having room for a final newline, abort */
1169 /*************************************************
1170 * Setup host for proxy protocol *
1171 *************************************************/
1172 /* The function configures the connection based on a header from the
1173 inbound host to use Proxy Protocol. The specification is very exact
1174 so exit with an error if do not find the exact required pieces. This
1175 includes an incorrect number of spaces separating args.
1178 Returns: Boolean success
1182 setup_proxy_protocol_host()
1194 struct { /* TCP/UDP over IPv4, len = 12 */
1200 struct { /* TCP/UDP over IPv6, len = 36 */
1201 uint8_t src_addr[16];
1202 uint8_t dst_addr[16];
1206 struct { /* AF_UNIX sockets, len = 216 */
1207 uschar src_addr[108];
1208 uschar dst_addr[108];
1214 /* Temp variables used in PPv2 address:port parsing */
1216 char tmpip[INET_ADDRSTRLEN];
1217 struct sockaddr_in tmpaddr;
1218 char tmpip6[INET6_ADDRSTRLEN];
1219 struct sockaddr_in6 tmpaddr6;
1221 /* We can't read "all data until end" because while SMTP is
1222 server-speaks-first, the TLS handshake is client-speaks-first, so for
1223 TLS-on-connect ports the proxy protocol header will usually be immediately
1224 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1225 reinject data for reading by those. So instead we first read "enough to be
1226 safely read within the header, and figure out how much more to read".
1227 For v1 we will later read to the end-of-line, for v2 we will read based upon
1230 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1231 data is needed total. For v1, where the line looks like:
1232 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1234 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1235 We seem to support that. So, if we read 14 octets then we can tell if we're
1236 v2 or v1. If we're v1, we can continue reading as normal.
1238 If we're v2, we can't slurp up the entire header. We need the length in the
1239 15th & 16th octets, then to read everything after that.
1241 So to safely handle v1 and v2, with client-sent-first supported correctly,
1242 we have to do a minimum of 3 read calls, not 1. Eww.
1245 #define PROXY_INITIAL_READ 14
1246 #define PROXY_V2_HEADER_SIZE 16
1247 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1248 # error Code bug in sizes of data to read for proxy usage
1253 int fd = fileno(smtp_in);
1254 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1255 uschar * iptype; /* To display debug info */
1256 socklen_t vslen = sizeof(struct timeval);
1259 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1260 ALARM(proxy_protocol_timeout);
1264 /* The inbound host was declared to be a Proxy Protocol host, so
1265 don't do a PEEK into the data, actually slurp up enough to be
1266 "safe". Can't take it all because TLS-on-connect clients follow
1267 immediately with TLS handshake. */
1268 ret = read(fd, &hdr, PROXY_INITIAL_READ);
1270 while (ret == -1 && errno == EINTR && !had_command_timeout);
1275 /* For v2, handle reading the length, and then the rest. */
1276 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1281 /* First get the length fields. */
1284 retmore = read(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ);
1285 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1290 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1292 /* May 2014: haproxy combined the version and command into one byte to
1293 allow two full bytes for the length field in order to proxy SSL
1294 connections. SSL Proxy is not supported in this version of Exim, but
1295 must still separate values here. */
1299 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1303 /* The v2 header will always be 16 bytes per the spec. */
1304 size = 16 + ntohs(hdr.v2.len);
1305 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1306 size, (int)sizeof(hdr));
1308 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1309 amount that we need. Double-check that the size is not unreasonable, then
1311 if (size > sizeof(hdr))
1313 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1321 retmore = read(fd, (uschar*)&hdr + ret, size-ret);
1322 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1326 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1327 } while (ret < size);
1329 } /* end scope for getting rest of data for v2 */
1331 /* At this point: if PROXYv2, we've read the exact size required for all data;
1332 if PROXYv1 then we've read "less than required for any valid line" and should
1335 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1337 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1341 case 0x01: /* PROXY command */
1344 case 0x11: /* TCPv4 address type */
1346 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1347 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1348 if (!string_is_ip_address(US tmpip, NULL))
1350 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1353 proxy_local_address = sender_host_address;
1354 sender_host_address = string_copy(US tmpip);
1355 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1356 proxy_local_port = sender_host_port;
1357 sender_host_port = tmpport;
1358 /* Save dest ip/port */
1359 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1360 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1361 if (!string_is_ip_address(US tmpip, NULL))
1363 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1366 proxy_external_address = string_copy(US tmpip);
1367 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1368 proxy_external_port = tmpport;
1370 case 0x21: /* TCPv6 address type */
1372 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1373 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1374 if (!string_is_ip_address(US tmpip6, NULL))
1376 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1379 proxy_local_address = sender_host_address;
1380 sender_host_address = string_copy(US tmpip6);
1381 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1382 proxy_local_port = sender_host_port;
1383 sender_host_port = tmpport;
1384 /* Save dest ip/port */
1385 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1386 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1387 if (!string_is_ip_address(US tmpip6, NULL))
1389 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1392 proxy_external_address = string_copy(US tmpip6);
1393 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1394 proxy_external_port = tmpport;
1398 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1402 /* Unsupported protocol, keep local connection address */
1404 case 0x00: /* LOCAL command */
1405 /* Keep local connection address for LOCAL */
1410 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1414 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1418 uschar *sp; /* Utility variables follow */
1423 /* get the rest of the line */
1424 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1429 p = string_copy(hdr.v1.line);
1430 end = memchr(p, '\r', ret - 1);
1432 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1434 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1437 *end = '\0'; /* Terminate the string */
1438 size = end + 2 - p; /* Skip header + CRLF */
1439 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1440 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1441 /* Step through the string looking for the required fields. Ensure
1442 strict adherence to required formatting, exit for any error. */
1444 if (!isspace(*(p++)))
1446 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1449 if (!Ustrncmp(p, CCS"TCP4", 4))
1451 else if (!Ustrncmp(p,CCS"TCP6", 4))
1453 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1455 iptype = US"Unknown";
1460 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1464 p += Ustrlen(iptype);
1465 if (!isspace(*(p++)))
1467 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1470 /* Find the end of the arg */
1471 if ((sp = Ustrchr(p, ' ')) == NULL)
1474 debug_printf("Did not find proxied src %s\n", iptype);
1478 if(!string_is_ip_address(p, NULL))
1481 debug_printf("Proxied src arg is not an %s address\n", iptype);
1484 proxy_local_address = sender_host_address;
1485 sender_host_address = p;
1487 if ((sp = Ustrchr(p, ' ')) == NULL)
1490 debug_printf("Did not find proxy dest %s\n", iptype);
1494 if(!string_is_ip_address(p, NULL))
1497 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1500 proxy_external_address = p;
1502 if ((sp = Ustrchr(p, ' ')) == NULL)
1504 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1508 tmp_port = strtol(CCS p, &endc, 10);
1509 if (*endc || tmp_port == 0)
1512 debug_printf("Proxied src port '%s' not an integer\n", p);
1515 proxy_local_port = sender_host_port;
1516 sender_host_port = tmp_port;
1518 if ((sp = Ustrchr(p, '\0')) == NULL)
1520 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1523 tmp_port = strtol(CCS p, &endc, 10);
1524 if (*endc || tmp_port == 0)
1527 debug_printf("Proxy dest port '%s' not an integer\n", p);
1530 proxy_external_port = tmp_port;
1531 /* Already checked for /r /n above. Good V1 header received. */
1535 /* Wrong protocol */
1536 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1537 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1543 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1544 yield = proxy_session;
1546 /* Don't flush any potential buffer contents. Any input on proxyfail
1547 should cause a synchronization failure */
1550 DEBUG(D_receive) if (had_command_timeout)
1551 debug_printf("Timeout while reading proxy header\n");
1556 sender_host_name = NULL;
1557 (void) host_name_lookup();
1558 host_build_sender_fullhost();
1562 f.proxy_session_failed = TRUE;
1564 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1572 /*************************************************
1573 * Read one command line *
1574 *************************************************/
1576 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1577 There are sites that don't do this, and in any case internal SMTP probably
1578 should check only for LF. Consequently, we check here for LF only. The line
1579 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1580 an unknown command. The command is read into the global smtp_cmd_buffer so that
1581 it is available via $smtp_command.
1583 The character reading routine sets up a timeout for each block actually read
1584 from the input (which may contain more than one command). We set up a special
1585 signal handler that closes down the session on a timeout. Control does not
1586 return when it runs.
1589 check_sync if TRUE, check synchronization rules if global option is TRUE
1590 buffer_lim maximum to buffer in lower layer
1592 Returns: a code identifying the command (enumerated above)
1596 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1600 BOOL hadnull = FALSE;
1602 had_command_timeout = 0;
1603 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1605 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1607 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1609 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1617 smtp_cmd_buffer[ptr++] = c;
1620 receive_linecount++; /* For BSMTP errors */
1621 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1623 /* If hit end of file, return pseudo EOF command. Whether we have a
1624 part-line already read doesn't matter, since this is an error state. */
1626 if (c == EOF) return EOF_CMD;
1628 /* Remove any CR and white space at the end of the line, and terminate the
1631 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1632 smtp_cmd_buffer[ptr] = 0;
1634 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1636 /* NULLs are not allowed in SMTP commands */
1638 if (hadnull) return BADCHAR_CMD;
1640 /* Scan command list and return identity, having set the data pointer
1641 to the start of the actual data characters. Check for SMTP synchronization
1644 for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
1646 #ifdef SUPPORT_PROXY
1647 /* Only allow QUIT command if Proxy Protocol parsing failed */
1648 if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
1652 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1653 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1654 || smtp_cmd_buffer[p->len] == 0
1655 || smtp_cmd_buffer[p->len] == ' '
1658 if (smtp_inptr < smtp_inend && /* Outstanding input */
1659 p->cmd < sync_cmd_limit && /* Command should sync */
1660 check_sync && /* Local flag set */
1661 smtp_enforce_sync && /* Global flag set */
1662 sender_host_address != NULL && /* Not local input */
1663 !f.sender_host_notsocket) /* Really is a socket */
1666 /* The variables $smtp_command and $smtp_command_argument point into the
1667 unmodified input buffer. A copy of the latter is taken for actual
1668 processing, so that it can be chopped up into separate parts if necessary,
1669 for example, when processing a MAIL command options such as SIZE that can
1670 follow the sender address. */
1672 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1673 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1674 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1675 smtp_cmd_data = smtp_data_buffer;
1677 /* Count non-mail commands from those hosts that are controlled in this
1678 way. The default is all hosts. We don't waste effort checking the list
1679 until we get a non-mail command, but then cache the result to save checking
1680 again. If there's a DEFER while checking the host, assume it's in the list.
1682 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1683 start of each incoming message by fiddling with the value in the table. */
1685 if (!p->is_mail_cmd)
1687 if (count_nonmail == TRUE_UNSET) count_nonmail =
1688 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1689 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1690 return TOO_MANY_NONMAIL_CMD;
1693 /* If there is data for a command that does not expect it, generate the
1696 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1700 #ifdef SUPPORT_PROXY
1701 /* Only allow QUIT command if Proxy Protocol parsing failed */
1702 if (proxy_session && f.proxy_session_failed)
1703 return PROXY_FAIL_IGNORE_CMD;
1706 /* Enforce synchronization for unknown commands */
1708 if ( smtp_inptr < smtp_inend /* Outstanding input */
1709 && check_sync /* Local flag set */
1710 && smtp_enforce_sync /* Global flag set */
1711 && sender_host_address /* Not local input */
1712 && !f.sender_host_notsocket) /* Really is a socket */
1720 /*************************************************
1721 * Forced closedown of call *
1722 *************************************************/
1724 /* This function is called from log.c when Exim is dying because of a serious
1725 disaster, and also from some other places. If an incoming non-batched SMTP
1726 channel is open, it swallows the rest of the incoming message if in the DATA
1727 phase, sends the reply string, and gives an error to all subsequent commands
1728 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1732 message SMTP reply string to send, excluding the code
1738 smtp_closedown(uschar *message)
1740 if (!smtp_in || smtp_batched_input) return;
1741 receive_swallow_smtp();
1742 smtp_printf("421 %s\r\n", FALSE, message);
1744 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1750 f.smtp_in_quit = TRUE;
1751 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1756 smtp_printf("250 Reset OK\r\n", FALSE);
1760 smtp_printf("421 %s\r\n", FALSE, message);
1768 /*************************************************
1769 * Set up connection info for logging *
1770 *************************************************/
1772 /* This function is called when logging information about an SMTP connection.
1773 It sets up appropriate source information, depending on the type of connection.
1774 If sender_fullhost is NULL, we are at a very early stage of the connection;
1775 just use the IP address.
1778 Returns: a string describing the connection
1782 smtp_get_connection_info(void)
1784 const uschar * hostname = sender_fullhost
1785 ? sender_fullhost : sender_host_address;
1788 return string_sprintf("SMTP connection from %s", hostname);
1790 if (f.sender_host_unknown || f.sender_host_notsocket)
1791 return string_sprintf("SMTP connection from %s", sender_ident);
1794 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1796 if (LOGGING(incoming_interface) && interface_address)
1797 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1798 interface_address, interface_port);
1800 return string_sprintf("SMTP connection from %s", hostname);
1806 /* Append TLS-related information to a log line
1809 g String under construction: allocated string to extend, or NULL
1811 Returns: Allocated string or NULL
1814 s_tlslog(gstring * g)
1816 if (LOGGING(tls_cipher) && tls_in.cipher)
1818 g = string_append(g, 2, US" X=", tls_in.cipher);
1819 #ifndef DISABLE_TLS_RESUME
1820 if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
1821 g = string_catn(g, US"*", 1);
1824 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1825 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1826 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1827 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1828 if (LOGGING(tls_sni) && tls_in.sni)
1829 g = string_append(g, 2, US" SNI=", string_printing2(tls_in.sni, SP_TAB|SP_SPACE));
1837 s_connhad_log(gstring * g)
1839 const uschar * sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE
1840 ? US" C=..." : US" C=";
1842 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1843 if (smtp_connection_had[i] != SCH_NONE)
1845 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1848 for (int i = 0; i < smtp_ch_index; i++, sep = US",")
1849 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1854 /*************************************************
1855 * Log lack of MAIL if so configured *
1856 *************************************************/
1858 /* This function is called when an SMTP session ends. If the log selector
1859 smtp_no_mail is set, write a log line giving some details of what has happened
1860 in the SMTP session.
1867 smtp_log_no_mail(void)
1872 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1875 if (sender_host_authenticated)
1877 g = string_append(g, 2, US" A=", sender_host_authenticated);
1878 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1885 g = s_connhad_log(g);
1887 if (!(s = string_from_gstring(g))) s = US"";
1889 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1890 f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
1891 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1895 /* Return list of recent smtp commands */
1900 gstring * list = NULL;
1903 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1904 if (smtp_connection_had[i] != SCH_NONE)
1905 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1907 for (int i = 0; i < smtp_ch_index; i++)
1908 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1910 s = string_from_gstring(list);
1911 return s ? s : US"";
1917 /*************************************************
1918 * Check HELO line and set sender_helo_name *
1919 *************************************************/
1921 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1922 the domain name of the sending host, or an ip literal in square brackets. The
1923 argument is placed in sender_helo_name, which is in malloc store, because it
1924 must persist over multiple incoming messages. If helo_accept_junk is set, this
1925 host is permitted to send any old junk (needed for some broken hosts).
1926 Otherwise, helo_allow_chars can be used for rogue characters in general
1927 (typically people want to let in underscores).
1930 s the data portion of the line (already past any white space)
1932 Returns: TRUE or FALSE
1936 check_helo(uschar *s)
1939 uschar *end = s + Ustrlen(s);
1940 BOOL yield = fl.helo_accept_junk;
1942 /* Discard any previous helo name */
1944 sender_helo_name = NULL;
1946 /* Skip tests if junk is permitted. */
1950 /* Allow the new standard form for IPv6 address literals, namely,
1951 [IPv6:....], and because someone is bound to use it, allow an equivalent
1952 IPv4 form. Allow plain addresses as well. */
1959 if (strncmpic(s, US"[IPv6:", 6) == 0)
1960 yield = (string_is_ip_address(s+6, NULL) == 6);
1961 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1962 yield = (string_is_ip_address(s+6, NULL) == 4);
1964 yield = (string_is_ip_address(s+1, NULL) != 0);
1969 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1970 that have been configured (usually underscore - sigh). */
1973 for (yield = TRUE; *s; s++)
1974 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1975 Ustrchr(helo_allow_chars, *s) == NULL)
1981 /* Save argument if OK */
1983 if (yield) sender_helo_name = string_copy_perm(start, TRUE);
1991 /*************************************************
1992 * Extract SMTP command option *
1993 *************************************************/
1995 /* This function picks the next option setting off the end of smtp_cmd_data. It
1996 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
1997 things that can appear there.
2000 name point this at the name
2001 value point this at the data string
2003 Returns: TRUE if found an option
2007 extract_option(uschar **name, uschar **value)
2011 if (Ustrlen(smtp_cmd_data) <= 0) return FALSE;
2012 v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
2013 while (v > smtp_cmd_data && isspace(*v)) v--;
2016 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
2018 /* Take care to not stop at a space embedded in a quoted local-part */
2021 do v--; while (v > smtp_cmd_data && *v != '"');
2022 if (v <= smtp_cmd_data) return FALSE;
2026 if (v <= smtp_cmd_data) return FALSE;
2031 while (n > smtp_cmd_data && isalpha(n[-1])) n--;
2032 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
2033 if (n <= smtp_cmd_data || !isspace(n[-1])) return FALSE;
2050 /*************************************************
2051 * Reset for new message *
2052 *************************************************/
2054 /* This function is called whenever the SMTP session is reset from
2055 within either of the setup functions; also from the daemon loop.
2057 Argument: the stacking pool storage reset point
2062 smtp_reset(void *reset_point)
2064 recipients_list = NULL;
2065 rcpt_count = rcpt_defer_count = rcpt_fail_count =
2066 raw_recipients_count = recipients_count = recipients_list_max = 0;
2067 message_linecount = 0;
2069 message_body = message_body_end = NULL;
2070 acl_added_headers = NULL;
2071 acl_removed_headers = NULL;
2072 f.queue_only_policy = FALSE;
2073 rcpt_smtp_response = NULL;
2074 fl.rcpt_smtp_response_same = TRUE;
2075 fl.rcpt_in_progress = FALSE;
2076 f.deliver_freeze = FALSE; /* Can be set by ACL */
2077 freeze_tell = freeze_tell_config; /* Can be set by ACL */
2078 fake_response = OK; /* Can be set by ACL */
2079 #ifdef WITH_CONTENT_SCAN
2080 f.no_mbox_unspool = FALSE; /* Can be set by ACL */
2082 f.submission_mode = FALSE; /* Can be set by ACL */
2083 f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
2084 f.active_local_from_check = local_from_check; /* Can be set by ACL */
2085 f.active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
2086 sending_ip_address = NULL;
2087 return_path = sender_address = NULL;
2088 deliver_localpart_data = deliver_domain_data =
2089 recipient_data = sender_data = NULL; /* Can be set by ACL */
2090 recipient_verify_failure = NULL;
2091 deliver_localpart_parent = deliver_localpart_orig = NULL;
2092 deliver_domain_parent = deliver_domain_orig = NULL;
2093 callout_address = NULL;
2094 submission_name = NULL; /* Can be set by ACL */
2095 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
2096 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
2097 sender_verified_list = NULL; /* No senders verified */
2098 memset(sender_address_cache, 0, sizeof(sender_address_cache));
2099 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
2101 authenticated_sender = NULL;
2102 #ifdef EXPERIMENTAL_BRIGHTMAIL
2104 bmi_verdicts = NULL;
2106 dnslist_domain = dnslist_matched = NULL;
2108 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2109 spf_result_guessed = FALSE;
2111 #ifndef DISABLE_DKIM
2112 dkim_cur_signer = dkim_signers =
2113 dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
2114 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2115 f.dkim_disable_verify = FALSE;
2116 dkim_collect_input = 0;
2117 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2118 dkim_key_length = 0;
2120 #ifdef SUPPORT_DMARC
2121 f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
2122 dmarc_domain_policy = dmarc_status = dmarc_status_text =
2123 dmarc_used_domain = NULL;
2125 #ifdef EXPERIMENTAL_ARC
2126 arc_state = arc_state_reason = NULL;
2127 arc_received_instance = 0;
2131 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2132 #ifndef DISABLE_PRDR
2133 prdr_requested = FALSE;
2136 message_smtputf8 = FALSE;
2138 body_linecount = body_zerocount = 0;
2140 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2141 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2142 /* Note that ratelimiters_conn persists across resets. */
2144 /* Reset message ACL variables */
2148 /* Warning log messages are saved in malloc store. They are saved to avoid
2149 repetition in the same message, but it seems right to repeat them for different
2152 while (acl_warn_logged)
2154 string_item *this = acl_warn_logged;
2155 acl_warn_logged = acl_warn_logged->next;
2160 store_reset(reset_point);
2163 return store_mark();
2170 /*************************************************
2171 * Initialize for incoming batched SMTP message *
2172 *************************************************/
2174 /* This function is called from smtp_setup_msg() in the case when
2175 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2176 of messages in one file with SMTP commands between them. All errors must be
2177 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2178 relevant. After an error on a sender, or an invalid recipient, the remainder
2179 of the message is skipped. The value of received_protocol is already set.
2182 Returns: > 0 message successfully started (reached DATA)
2183 = 0 QUIT read or end of file reached
2184 < 0 should not occur
2188 smtp_setup_batch_msg(void)
2191 rmark reset_point = store_mark();
2193 /* Save the line count at the start of each transaction - single commands
2194 like HELO and RSET count as whole transactions. */
2196 bsmtp_transaction_linecount = receive_linecount;
2198 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2200 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2201 reset_point = smtp_reset(reset_point); /* Reset for start of message */
2203 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2204 value. The values are 2 larger than the required yield of the function. */
2209 uschar *recipient = NULL;
2210 int start, end, sender_domain, recipient_domain;
2212 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2214 /* The HELO/EHLO commands set sender_address_helo if they have
2215 valid data; otherwise they are ignored, except that they do
2216 a reset of the state. */
2221 check_helo(smtp_cmd_data);
2225 cancel_cutthrough_connection(TRUE, US"RSET received");
2226 reset_point = smtp_reset(reset_point);
2227 bsmtp_transaction_linecount = receive_linecount;
2231 /* The MAIL FROM command requires an address as an operand. All we
2232 do here is to parse it for syntactic correctness. The form "<>" is
2233 a special case which converts into an empty string. The start/end
2234 pointers in the original are not used further for this address, as
2235 it is the canonical extracted address which is all that is kept. */
2238 smtp_mailcmd_count++; /* Count for no-mail log */
2240 /* The function moan_smtp_batch() does not return. */
2241 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2243 if (smtp_cmd_data[0] == 0)
2244 /* The function moan_smtp_batch() does not return. */
2245 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2247 /* Reset to start of message */
2249 cancel_cutthrough_connection(TRUE, US"MAIL received");
2250 reset_point = smtp_reset(reset_point);
2252 /* Apply SMTP rewrite */
2254 raw_sender = rewrite_existflags & rewrite_smtp
2255 /* deconst ok as smtp_cmd_data was not const */
2256 ? US rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL,
2257 FALSE, US"", global_rewrite_rules)
2260 /* Extract the address; the TRUE flag allows <> as valid */
2263 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2267 /* The function moan_smtp_batch() does not return. */
2268 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2270 sender_address = string_copy(raw_sender);
2272 /* Qualify unqualified sender addresses if permitted to do so. */
2275 && sender_address[0] != 0 && sender_address[0] != '@')
2276 if (f.allow_unqualified_sender)
2278 /* deconst ok as sender_address was not const */
2279 sender_address = US rewrite_address_qualify(sender_address, FALSE);
2280 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2281 "and rewritten\n", raw_sender);
2283 /* The function moan_smtp_batch() does not return. */
2285 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2290 /* The RCPT TO command requires an address as an operand. All we do
2291 here is to parse it for syntactic correctness. There may be any number
2292 of RCPT TO commands, specifying multiple senders. We build them all into
2293 a data structure that is in argc/argv format. The start/end values
2294 given by parse_extract_address are not used, as we keep only the
2295 extracted address. */
2298 if (!sender_address)
2299 /* The function moan_smtp_batch() does not return. */
2300 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2302 if (smtp_cmd_data[0] == 0)
2303 /* The function moan_smtp_batch() does not return. */
2304 moan_smtp_batch(smtp_cmd_buffer,
2305 "501 RCPT TO must have an address operand");
2307 /* Check maximum number allowed */
2309 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2310 /* The function moan_smtp_batch() does not return. */
2311 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2312 recipients_max_reject? "552": "452");
2314 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2315 recipient address */
2317 recipient = rewrite_existflags & rewrite_smtp
2318 /* deconst ok as smtp_cmd_data was not const */
2319 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2320 global_rewrite_rules)
2323 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2324 &recipient_domain, FALSE);
2327 /* The function moan_smtp_batch() does not return. */
2328 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2330 /* If the recipient address is unqualified, qualify it if permitted. Then
2331 add it to the list of recipients. */
2333 if (!recipient_domain)
2334 if (f.allow_unqualified_recipient)
2336 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2338 /* deconst ok as recipient was not const */
2339 recipient = US rewrite_address_qualify(recipient, TRUE);
2341 /* The function moan_smtp_batch() does not return. */
2343 moan_smtp_batch(smtp_cmd_buffer,
2344 "501 recipient address must contain a domain");
2346 receive_add_recipient(recipient, -1);
2350 /* The DATA command is legal only if it follows successful MAIL FROM
2351 and RCPT TO commands. This function is complete when a valid DATA
2352 command is encountered. */
2355 if (!sender_address || recipients_count <= 0)
2356 /* The function moan_smtp_batch() does not return. */
2357 if (!sender_address)
2358 moan_smtp_batch(smtp_cmd_buffer,
2359 "503 MAIL FROM:<sender> command must precede DATA");
2361 moan_smtp_batch(smtp_cmd_buffer,
2362 "503 RCPT TO:<recipient> must precede DATA");
2365 done = 3; /* DATA successfully achieved */
2366 message_ended = END_NOTENDED; /* Indicate in middle of message */
2371 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2378 bsmtp_transaction_linecount = receive_linecount;
2383 f.smtp_in_quit = TRUE;
2390 /* The function moan_smtp_batch() does not return. */
2391 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2396 /* The function moan_smtp_batch() does not return. */
2397 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2402 /* The function moan_smtp_batch() does not return. */
2403 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2408 return done - 2; /* Convert yield values */
2416 smtp_log_tls_fail(uschar * errstr)
2418 uschar * conn_info = smtp_get_connection_info();
2420 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2421 /* I'd like to get separated H= here, but too hard for now */
2423 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2437 socklen_t len = sizeof(is_fastopen);
2439 /* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
2440 TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
2442 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
2447 debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
2448 f.tcp_in_fastopen = TRUE;
2451 else DEBUG(D_receive)
2452 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2454 # elif defined(TCP_INFO)
2455 struct tcp_info tinfo;
2456 socklen_t len = sizeof(tinfo);
2458 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
2459 # ifdef TCPI_OPT_SYN_DATA /* FreeBSD 11,12 do not seem to have this yet */
2460 if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
2463 debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
2464 f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
2468 if (tinfo.tcpi_state == TCP_SYN_RECV) /* Not seen on FreeBSD 12.1 */
2471 debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
2472 f.tcp_in_fastopen = TRUE;
2474 else DEBUG(D_receive)
2475 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2481 /*************************************************
2482 * Start an SMTP session *
2483 *************************************************/
2485 /* This function is called at the start of an SMTP session. Thereafter,
2486 smtp_setup_msg() is called to initiate each separate message. This
2487 function does host-specific testing, and outputs the banner line.
2490 Returns: FALSE if the session can not continue; something has
2491 gone wrong, or the connection to the host is blocked
2495 smtp_start_session(void)
2498 uschar *user_msg, *log_msg;
2503 gettimeofday(&smtp_connection_start, NULL);
2504 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2505 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2508 /* Default values for certain variables */
2510 fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
2511 smtp_mailcmd_count = 0;
2512 count_nonmail = TRUE_UNSET;
2513 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2514 smtp_delay_mail = smtp_rlm_base;
2515 fl.auth_advertised = FALSE;
2516 f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
2517 f.pipelining_enable = TRUE;
2518 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2519 fl.smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2521 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2522 authentication settings from -oMaa to remain in force. */
2524 if (!host_checking && !f.sender_host_notsocket)
2525 sender_host_auth_pubname = sender_host_authenticated = NULL;
2526 authenticated_by = NULL;
2529 tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
2530 tls_in.ourcert = tls_in.peercert = NULL;
2532 tls_in.ocsp = OCSP_NOT_REQ;
2533 fl.tls_advertised = FALSE;
2535 fl.dsn_advertised = FALSE;
2537 fl.smtputf8_advertised = FALSE;
2540 /* Reset ACL connection variables */
2544 /* Allow for trailing 0 in the command and data buffers. Tainted. */
2546 smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, TRUE);
2548 smtp_cmd_buffer[0] = 0;
2549 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2551 /* For batched input, the protocol setting can be overridden from the
2552 command line by a trusted caller. */
2554 if (smtp_batched_input)
2556 if (!received_protocol) received_protocol = US"local-bsmtp";
2559 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2560 reset later if any of EHLO/AUTH/STARTTLS are received. */
2564 (sender_host_address ? protocols : protocols_local) [pnormal];
2566 /* Set up the buffer for inputting using direct read() calls, and arrange to
2567 call the local functions instead of the standard C ones. Place a NUL at the
2568 end of the buffer to safety-stop C-string reads from it. */
2570 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2571 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2572 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2574 receive_getc = smtp_getc;
2575 receive_getbuf = smtp_getbuf;
2576 receive_get_cache = smtp_get_cache;
2577 receive_ungetc = smtp_ungetc;
2578 receive_feof = smtp_feof;
2579 receive_ferror = smtp_ferror;
2580 receive_smtp_buffered = smtp_buffered;
2581 lwr_receive_getc = NULL;
2582 lwr_receive_getbuf = NULL;
2583 lwr_receive_ungetc = NULL;
2584 smtp_inptr = smtp_inend = smtp_inbuffer;
2585 smtp_had_eof = smtp_had_error = 0;
2587 /* Set up the message size limit; this may be host-specific */
2589 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2590 if (expand_string_message)
2592 if (thismessage_size_limit == -1)
2593 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2594 "%s", expand_string_message);
2596 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2597 "%s", expand_string_message);
2598 smtp_closedown(US"Temporary local problem - please try later");
2602 /* When a message is input locally via the -bs or -bS options, sender_host_
2603 unknown is set unless -oMa was used to force an IP address, in which case it
2604 is checked like a real remote connection. When -bs is used from inetd, this
2605 flag is not set, causing the sending host to be checked. The code that deals
2606 with IP source routing (if configured) is never required for -bs or -bS and
2607 the flag sender_host_notsocket is used to suppress it.
2609 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2610 reserve for certain hosts and/or networks. */
2612 if (!f.sender_host_unknown)
2615 BOOL reserved_host = FALSE;
2617 /* Look up IP options (source routing info) on the socket if this is not an
2618 -oMa "host", and if any are found, log them and drop the connection.
2620 Linux (and others now, see below) is different to everyone else, so there
2621 has to be some conditional compilation here. Versions of Linux before 2.1.15
2622 used a structure whose name was "options". Somebody finally realized that
2623 this name was silly, and it got changed to "ip_options". I use the
2624 newer name here, but there is a fudge in the script that sets up os.h
2625 to define a macro in older Linux systems.
2627 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2628 glibc 2, which has chosen ip_opts for the structure name. This is now
2629 really a glibc thing rather than a Linux thing, so the condition name
2630 has been changed to reflect this. It is relevant also to GNU/Hurd.
2632 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2633 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2634 a special macro defined in the os.h file.
2636 Some DGUX versions on older hardware appear not to support IP options at
2637 all, so there is now a general macro which can be set to cut out this
2640 How to do this properly in IPv6 is not yet known. */
2642 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2644 #ifdef GLIBC_IP_OPTIONS
2645 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2650 #elif defined DARWIN_IP_OPTIONS
2656 if (!host_checking && !f.sender_host_notsocket)
2659 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2660 struct ip_options *ipopt = store_get(optlen, FALSE);
2662 struct ip_opts ipoptblock;
2663 struct ip_opts *ipopt = &ipoptblock;
2664 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2666 struct ipoption ipoptblock;
2667 struct ipoption *ipopt = &ipoptblock;
2668 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2671 /* Occasional genuine failures of getsockopt() have been seen - for
2672 example, "reset by peer". Therefore, just log and give up on this
2673 call, unless the error is ENOPROTOOPT. This error is given by systems
2674 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2675 of writing. So for that error, carry on - we just can't do an IP options
2678 DEBUG(D_receive) debug_printf("checking for IP options\n");
2680 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2683 if (errno != ENOPROTOOPT)
2685 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2686 host_and_ident(FALSE), strerror(errno));
2687 smtp_printf("451 SMTP service not available\r\n", FALSE);
2692 /* Deal with any IP options that are set. On the systems I have looked at,
2693 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2694 more logging data than will fit in big_buffer. Nevertheless, after somebody
2695 questioned this code, I've added in some paranoid checking. */
2697 else if (optlen > 0)
2699 uschar *p = big_buffer;
2700 uschar *pend = big_buffer + big_buffer_size;
2703 struct in_addr addr;
2706 uschar *optstart = US (ipopt->__data);
2708 uschar *optstart = US (ipopt->ip_opts);
2710 uschar *optstart = US (ipopt->ipopt_list);
2713 DEBUG(D_receive) debug_printf("IP options exist\n");
2715 Ustrcpy(p, "IP options on incoming call:");
2718 for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
2731 if (!string_format(p, pend-p, " %s [@%s",
2732 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2734 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2736 inet_ntoa(ipopt->ip_dst)))
2738 inet_ntoa(ipopt->ipopt_dst)))
2746 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2748 while (optcount-- > 0)
2750 memcpy(&addr, adptr, sizeof(addr));
2751 if (!string_format(p, pend - p - 1, "%s%s",
2752 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2758 adptr += sizeof(struct in_addr);
2766 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2769 for (int i = 0; i < opt[1]; i++)
2770 p += sprintf(CS p, "%2.2x ", opt[i]);
2778 log_write(0, LOG_MAIN, "%s", big_buffer);
2780 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2782 log_write(0, LOG_MAIN|LOG_REJECT,
2783 "connection from %s refused (IP options)", host_and_ident(FALSE));
2785 smtp_printf("554 SMTP service not available\r\n", FALSE);
2789 /* Length of options = 0 => there are no options */
2791 else DEBUG(D_receive) debug_printf("no IP options found\n");
2793 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2795 /* Set keep-alive in socket options. The option is on by default. This
2796 setting is an attempt to get rid of some hanging connections that stick in
2797 read() when the remote end (usually a dialup) goes away. */
2799 if (smtp_accept_keepalive && !f.sender_host_notsocket)
2800 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2802 /* If the current host matches host_lookup, set the name by doing a
2803 reverse lookup. On failure, sender_host_name will be NULL and
2804 host_lookup_failed will be TRUE. This may or may not be serious - optional
2807 if (verify_check_host(&host_lookup) == OK)
2809 (void)host_name_lookup();
2810 host_build_sender_fullhost();
2813 /* Delay this until we have the full name, if it is looked up. */
2815 set_process_info("handling incoming connection from %s",
2816 host_and_ident(FALSE));
2818 /* Expand smtp_receive_timeout, if needed */
2820 if (smtp_receive_timeout_s)
2823 if ( !(exp = expand_string(smtp_receive_timeout_s))
2825 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2827 log_write(0, LOG_MAIN|LOG_PANIC,
2828 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2831 /* Test for explicit connection rejection */
2833 if (verify_check_host(&host_reject_connection) == OK)
2835 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2836 "from %s (host_reject_connection)", host_and_ident(FALSE));
2837 smtp_printf("554 SMTP service not available\r\n", FALSE);
2841 /* Test with TCP Wrappers if so configured. There is a problem in that
2842 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2843 such as disks dying. In these cases, it is desirable to reject with a 4xx
2844 error instead of a 5xx error. There isn't a "right" way to detect such
2845 problems. The following kludge is used: errno is zeroed before calling
2846 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2847 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2850 #ifdef USE_TCP_WRAPPERS
2852 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2853 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2854 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2855 expand_string_message);
2857 if (!hosts_ctl(tcp_wrappers_name,
2858 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2859 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2860 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2862 if (errno == 0 || errno == ENOENT)
2864 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2865 log_write(L_connection_reject,
2866 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2867 "(tcp wrappers)", host_and_ident(FALSE));
2868 smtp_printf("554 SMTP service not available\r\n", FALSE);
2872 int save_errno = errno;
2873 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2874 "errno value %d\n", save_errno);
2875 log_write(L_connection_reject,
2876 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2877 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2878 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2884 /* Check for reserved slots. The value of smtp_accept_count has already been
2885 incremented to include this process. */
2887 if (smtp_accept_max > 0 &&
2888 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2890 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2892 log_write(L_connection_reject,
2893 LOG_MAIN, "temporarily refused connection from %s: not in "
2894 "reserve list: connected=%d max=%d reserve=%d%s",
2895 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2896 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2897 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2898 "please try again later\r\n", FALSE, smtp_active_hostname);
2901 reserved_host = TRUE;
2904 /* If a load level above which only messages from reserved hosts are
2905 accepted is set, check the load. For incoming calls via the daemon, the
2906 check is done in the superior process if there are no reserved hosts, to
2907 save a fork. In all cases, the load average will already be available
2908 in a global variable at this point. */
2910 if (smtp_load_reserve >= 0 &&
2911 load_average > smtp_load_reserve &&
2913 verify_check_host(&smtp_reserve_hosts) != OK)
2915 log_write(L_connection_reject,
2916 LOG_MAIN, "temporarily refused connection from %s: not in "
2917 "reserve list and load average = %.2f", host_and_ident(FALSE),
2918 (double)load_average/1000.0);
2919 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2920 smtp_active_hostname);
2924 /* Determine whether unqualified senders or recipients are permitted
2925 for this host. Unfortunately, we have to do this every time, in order to
2926 set the flags so that they can be inspected when considering qualifying
2927 addresses in the headers. For a site that permits no qualification, this
2928 won't take long, however. */
2930 f.allow_unqualified_sender =
2931 verify_check_host(&sender_unqualified_hosts) == OK;
2933 f.allow_unqualified_recipient =
2934 verify_check_host(&recipient_unqualified_hosts) == OK;
2936 /* Determine whether HELO/EHLO is required for this host. The requirement
2937 can be hard or soft. */
2939 fl.helo_verify_required = verify_check_host(&helo_verify_hosts) == OK;
2940 if (!fl.helo_verify_required)
2941 fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2943 /* Determine whether this hosts is permitted to send syntactic junk
2944 after a HELO or EHLO command. */
2946 fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2949 /* For batch SMTP input we are now done. */
2951 if (smtp_batched_input) return TRUE;
2953 /* If valid Proxy Protocol source is connecting, set up session.
2954 Failure will not allow any SMTP function other than QUIT. */
2956 #ifdef SUPPORT_PROXY
2957 proxy_session = FALSE;
2958 f.proxy_session_failed = FALSE;
2959 if (check_proxy_protocol_host())
2960 setup_proxy_protocol_host();
2963 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2964 smtps port for use with older style SSL MTAs. */
2967 if (tls_in.on_connect)
2969 if (tls_server_start(&user_msg) != OK)
2970 return smtp_log_tls_fail(user_msg);
2971 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2975 /* Run the connect ACL if it exists */
2978 if (acl_smtp_connect)
2981 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
2984 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
2989 /* Output the initial message for a two-way SMTP connection. It may contain
2990 newlines, which then cause a multi-line response to be given. */
2992 code = US"220"; /* Default status code */
2993 esc = US""; /* Default extended status code */
2994 esclen = 0; /* Length of esc */
2998 if (!(s = expand_string(smtp_banner)))
2999 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
3000 "failed: %s", smtp_banner, expand_string_message);
3006 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
3010 esclen = codelen - 4;
3014 /* Remove any terminating newlines; might as well remove trailing space too */
3017 while (p > s && isspace(p[-1])) p--;
3018 s = string_copyn(s, p-s);
3020 /* It seems that CC:Mail is braindead, and assumes that the greeting message
3021 is all contained in a single IP packet. The original code wrote out the
3022 greeting using several calls to fprint/fputc, and on busy servers this could
3023 cause it to be split over more than one packet - which caused CC:Mail to fall
3024 over when it got the second part of the greeting after sending its first
3025 command. Sigh. To try to avoid this, build the complete greeting message
3026 first, and output it in one fell swoop. This gives a better chance of it
3027 ending up as a single packet. */
3029 ss = string_get(256);
3032 do /* At least once, in case we have an empty string */
3035 uschar *linebreak = Ustrchr(p, '\n');
3036 ss = string_catn(ss, code, 3);
3040 ss = string_catn(ss, US" ", 1);
3044 len = linebreak - p;
3045 ss = string_catn(ss, US"-", 1);
3047 ss = string_catn(ss, esc, esclen);
3048 ss = string_catn(ss, p, len);
3049 ss = string_catn(ss, US"\r\n", 2);
3055 /* Before we write the banner, check that there is no input pending, unless
3056 this synchronisation check is disabled. */
3058 #ifndef DISABLE_PIPE_CONNECT
3059 fl.pipe_connect_acceptable =
3060 sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
3063 if (fl.pipe_connect_acceptable)
3064 f.smtp_in_early_pipe_used = TRUE;
3070 unsigned n = smtp_inend - smtp_inptr;
3071 if (n > 128) n = 128;
3073 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
3074 "synchronization error (input sent without waiting for greeting): "
3075 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
3076 string_printing(string_copyn(smtp_inptr, n)));
3077 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
3081 /* Now output the banner */
3082 /*XXX the ehlo-resp code does its own tls/nontls bit. Maybe subroutine that? */
3085 #ifndef DISABLE_PIPE_CONNECT
3086 fl.pipe_connect_acceptable && pipeline_connect_sends(),
3090 string_from_gstring(ss));
3092 /* Attempt to see if we sent the banner before the last ACK of the 3-way
3093 handshake arrived. If so we must have managed a TFO. */
3096 if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
3106 /*************************************************
3107 * Handle SMTP syntax and protocol errors *
3108 *************************************************/
3110 /* Write to the log for SMTP syntax errors in incoming commands, if configured
3111 to do so. Then transmit the error response. The return value depends on the
3112 number of syntax and protocol errors in this SMTP session.
3115 type error type, given as a log flag bit
3116 code response code; <= 0 means don't send a response
3117 data data to reflect in the response (can be NULL)
3118 errmess the error message
3120 Returns: -1 limit of syntax/protocol errors NOT exceeded
3121 +1 limit of syntax/protocol errors IS exceeded
3123 These values fit in with the values of the "done" variable in the main
3124 processing loop in smtp_setup_msg(). */
3127 synprot_error(int type, int code, uschar *data, uschar *errmess)
3131 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
3132 type == L_smtp_syntax_error ? "syntax" : "protocol",
3133 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
3135 if (++synprot_error_count > smtp_max_synprot_errors)
3138 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3139 "syntax or protocol errors (last command was \"%s\", %s)",
3140 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
3141 string_from_gstring(s_connhad_log(NULL))
3147 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
3148 data ? data : US"", data ? US": " : US"", errmess);
3150 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
3159 /*************************************************
3160 * Send SMTP response, possibly multiline *
3161 *************************************************/
3163 /* There are, it seems, broken clients out there that cannot handle multiline
3164 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3165 output nothing for non-final calls, and only the first line for anything else.
3168 code SMTP code, may involve extended status codes
3169 codelen length of smtp code; if > 4 there's an ESC
3170 final FALSE if the last line isn't the final line
3171 msg message text, possibly containing newlines
3177 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3182 if (!final && f.no_multiline_responses) return;
3187 esclen = codelen - 4;
3190 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3191 have had the same. Note: this code is also present in smtp_printf(). It would
3192 be tidier to have it only in one place, but when it was added, it was easier to
3193 do it that way, so as not to have to mess with the code for the RCPT command,
3194 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3196 if (fl.rcpt_in_progress)
3198 if (rcpt_smtp_response == NULL)
3199 rcpt_smtp_response = string_copy(msg);
3200 else if (fl.rcpt_smtp_response_same &&
3201 Ustrcmp(rcpt_smtp_response, msg) != 0)
3202 fl.rcpt_smtp_response_same = FALSE;
3203 fl.rcpt_in_progress = FALSE;
3206 /* Now output the message, splitting it up into multiple lines if necessary.
3207 We only handle pipelining these responses as far as nonfinal/final groups,
3208 not the whole MAIL/RCPT/DATA response set. */
3212 uschar *nl = Ustrchr(msg, '\n');
3215 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3218 else if (nl[1] == 0 || f.no_multiline_responses)
3220 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3221 (int)(nl - msg), msg);
3226 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3228 Uskip_whitespace(&msg);
3236 /*************************************************
3237 * Parse user SMTP message *
3238 *************************************************/
3240 /* This function allows for user messages overriding the response code details
3241 by providing a suitable response code string at the start of the message
3242 user_msg. Check the message for starting with a response code and optionally an
3243 extended status code. If found, check that the first digit is valid, and if so,
3244 change the code pointer and length to use the replacement. An invalid code
3245 causes a panic log; in this case, if the log messages is the same as the user
3246 message, we must also adjust the value of the log message to show the code that
3247 is actually going to be used (the original one).
3249 This function is global because it is called from receive.c as well as within
3252 Note that the code length returned includes the terminating whitespace
3253 character, which is always included in the regex match.
3256 code SMTP code, may involve extended status codes
3257 codelen length of smtp code; if > 4 there's an ESC
3259 log_msg optional log message, to be adjusted with the new SMTP code
3260 check_valid if true, verify the response code
3266 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3272 if (!msg || !*msg) return;
3274 if ((n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
3275 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int))) < 0) return;
3277 if (check_valid && (*msg)[0] != (*code)[0])
3279 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3280 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3281 if (log_msg != NULL && *log_msg == *msg)
3282 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
3287 *codelen = ovector[1]; /* Includes final space */
3289 *msg += ovector[1]; /* Chop the code off the message */
3296 /*************************************************
3297 * Handle an ACL failure *
3298 *************************************************/
3300 /* This function is called when acl_check() fails. As well as calls from within
3301 this module, it is called from receive.c for an ACL after DATA. It sorts out
3302 logging the incident, and sends the error response. A message containing
3303 newlines is turned into a multiline SMTP response, but for logging, only the
3306 There's a table of default permanent failure response codes to use in
3307 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3308 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3309 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3310 state, because there are broken clients that try VRFY before RCPT. A 5xx
3311 response should be given only when the address is positively known to be
3312 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3313 no explicit code, but if there is one we let it know best.
3314 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3316 From Exim 4.63, it is possible to override the response code details by
3317 providing a suitable response code string at the start of the message provided
3318 in user_msg. The code's first digit is checked for validity.
3321 where where the ACL was called from
3323 user_msg a message that can be included in an SMTP response
3324 log_msg a message for logging
3326 Returns: 0 in most cases
3327 2 if the failure code was FAIL_DROP, in which case the
3328 SMTP connection should be dropped (this value fits with the
3329 "done" variable in smtp_setup_msg() below)
3333 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3335 BOOL drop = rc == FAIL_DROP;
3339 uschar *sender_info = US"";
3342 if (drop) rc = FAIL;
3344 /* Set the default SMTP code, and allow a user message to change it. */
3346 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3347 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3348 where != ACL_WHERE_VRFY);
3350 /* We used to have sender_address here; however, there was a bug that was not
3351 updating sender_address after a rewrite during a verify. When this bug was
3352 fixed, sender_address at this point became the rewritten address. I'm not sure
3353 this is what should be logged, so I've changed to logging the unrewritten
3354 address to retain backward compatibility. */
3358 #ifdef WITH_CONTENT_SCAN
3359 case ACL_WHERE_MIME: what = US"during MIME ACL checks"; break;
3361 case ACL_WHERE_PREDATA: what = US"DATA"; break;
3362 case ACL_WHERE_DATA: what = US"after DATA"; break;
3363 #ifndef DISABLE_PRDR
3364 case ACL_WHERE_PRDR: what = US"after DATA PRDR"; break;
3368 uschar * place = smtp_cmd_data ? smtp_cmd_data : US"in \"connect\" ACL";
3371 if (where == ACL_WHERE_AUTH) /* avoid logging auth creds */
3374 for (s = smtp_cmd_data; *s && !isspace(*s); ) s++;
3375 lim = s - smtp_cmd_data; /* atop after method */
3377 what = string_sprintf("%s %.*s", acl_wherenames[where], lim, place);
3382 case ACL_WHERE_RCPT:
3383 case ACL_WHERE_DATA:
3384 #ifdef WITH_CONTENT_SCAN
3385 case ACL_WHERE_MIME:
3387 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3388 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3389 sender_host_authenticated ? US" A=" : US"",
3390 sender_host_authenticated ? sender_host_authenticated : US"",
3391 sender_host_authenticated && authenticated_id ? US":" : US"",
3392 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3397 /* If there's been a sender verification failure with a specific message, and
3398 we have not sent a response about it yet, do so now, as a preliminary line for
3399 failures, but not defers. However, always log it for defer, and log it for fail
3400 unless the sender_verify_fail log selector has been turned off. */
3402 if (sender_verified_failed &&
3403 !testflag(sender_verified_failed, af_sverify_told))
3405 BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
3406 fl.rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3408 setflag(sender_verified_failed, af_sverify_told);
3410 if (rc != FAIL || LOGGING(sender_verify_fail))
3411 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3412 host_and_ident(TRUE),
3413 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3414 sender_verified_failed->address,
3415 (sender_verified_failed->message == NULL)? US"" :
3416 string_sprintf(": %s", sender_verified_failed->message));
3418 if (rc == FAIL && sender_verified_failed->user_message)
3419 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3420 testflag(sender_verified_failed, af_verify_pmfail)?
3421 "Postmaster verification failed while checking <%s>\n%s\n"
3422 "Several RFCs state that you are required to have a postmaster\n"
3423 "mailbox for each mail domain. This host does not accept mail\n"
3424 "from domains whose servers reject the postmaster address."
3426 testflag(sender_verified_failed, af_verify_nsfail)?
3427 "Callback setup failed while verifying <%s>\n%s\n"
3428 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3429 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3430 "RFC requirements, and stops you from receiving standard bounce\n"
3431 "messages. This host does not accept mail from domains whose servers\n"
3434 "Verification failed for <%s>\n%s",
3435 sender_verified_failed->address,
3436 sender_verified_failed->user_message));
3438 fl.rcpt_in_progress = save_rcpt_in_progress;
3441 /* Sort out text for logging */
3443 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3444 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3446 /* Send permanent failure response to the command, but the code used isn't
3447 always a 5xx one - see comments at the start of this function. If the original
3448 rc was FAIL_DROP we drop the connection and yield 2. */
3451 smtp_respond(smtp_code, codelen, TRUE,
3452 user_msg ? user_msg : US"Administrative prohibition");
3454 /* Send temporary failure response to the command. Don't give any details,
3455 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3456 verb, and for a header verify when smtp_return_error_details is set.
3458 This conditional logic is all somewhat of a mess because of the odd
3459 interactions between temp_details and return_error_details. One day it should
3460 be re-implemented in a tidier fashion. */
3463 if (f.acl_temp_details && user_msg)
3465 if ( smtp_return_error_details
3466 && sender_verified_failed
3467 && sender_verified_failed->message
3469 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3471 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3474 smtp_respond(smtp_code, codelen, TRUE,
3475 US"Temporary local problem - please try later");
3477 /* Log the incident to the logs that are specified by log_reject_target
3478 (default main, reject). This can be empty to suppress logging of rejections. If
3479 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3480 is closing if required and return 2. */
3482 if (log_reject_target != 0)
3485 gstring * g = s_tlslog(NULL);
3486 uschar * tls = string_from_gstring(g);
3487 if (!tls) tls = US"";
3489 uschar * tls = US"";
3491 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3492 log_reject_target, "%s%s%s %s%srejected %s%s",
3493 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3494 host_and_ident(TRUE),
3497 rc == FAIL ? US"" : US"temporarily ",
3501 if (!drop) return 0;
3503 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3504 smtp_get_connection_info());
3506 /* Run the not-quit ACL, but without any custom messages. This should not be a
3507 problem, because we get here only if some other ACL has issued "drop", and
3508 in that case, *its* custom messages will have been used above. */
3510 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3517 /*************************************************
3518 * Handle SMTP exit when QUIT is not given *
3519 *************************************************/
3521 /* This function provides a logging/statistics hook for when an SMTP connection
3522 is dropped on the floor or the other end goes away. It's a global function
3523 because it's called from receive.c as well as this module. As well as running
3524 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3525 response, either with a custom message from the ACL, or using a default. There
3526 is one case, however, when no message is output - after "drop". In that case,
3527 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3528 passed to this function.
3530 In case things go wrong while processing this function, causing an error that
3531 may re-enter this function, there is a recursion check.
3534 reason What $smtp_notquit_reason will be set to in the ACL;
3535 if NULL, the ACL is not run
3536 code The error code to return as part of the response
3537 defaultrespond The default message if there's no user_msg
3543 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3546 uschar *user_msg = NULL;
3547 uschar *log_msg = NULL;
3549 /* Check for recursive call */
3551 if (fl.smtp_exit_function_called)
3553 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3557 fl.smtp_exit_function_called = TRUE;
3559 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3561 if (acl_smtp_notquit && reason)
3563 smtp_notquit_reason = reason;
3564 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3565 &log_msg)) == ERROR)
3566 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3570 /* If the connection was dropped, we certainly are no longer talking TLS */
3571 tls_in.active.sock = -1;
3573 /* Write an SMTP response if we are expected to give one. As the default
3574 responses are all internal, they should be reasonable size. */
3576 if (code && defaultrespond)
3579 smtp_respond(code, 3, TRUE, user_msg);
3585 va_start(ap, defaultrespond);
3586 g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, CS defaultrespond, ap);
3588 smtp_printf("%s %s\r\n", FALSE, code, string_from_gstring(g));
3597 /*************************************************
3598 * Verify HELO argument *
3599 *************************************************/
3601 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3602 matched. It is also called from ACL processing if verify = helo is used and
3603 verification was not previously tried (i.e. helo_try_verify_hosts was not
3604 matched). The result of its processing is to set helo_verified and
3605 helo_verify_failed. These variables should both be FALSE for this function to
3608 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3609 for IPv6 ::ffff: literals.
3612 Returns: TRUE if testing was completed;
3613 FALSE on a temporary failure
3617 smtp_verify_helo(void)
3621 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3624 if (sender_helo_name == NULL)
3626 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3629 /* Deal with the case of -bs without an IP address */
3631 else if (sender_host_address == NULL)
3633 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3634 f.helo_verified = TRUE;
3637 /* Deal with the more common case when there is a sending IP address */
3639 else if (sender_helo_name[0] == '[')
3641 f.helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3642 Ustrlen(sender_host_address)) == 0;
3645 if (!f.helo_verified)
3647 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3648 f.helo_verified = Ustrncmp(sender_helo_name + 1,
3649 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3654 { if (f.helo_verified) debug_printf("matched host address\n"); }
3657 /* Do a reverse lookup if one hasn't already given a positive or negative
3658 response. If that fails, or the name doesn't match, try checking with a forward
3663 if (sender_host_name == NULL && !host_lookup_failed)
3664 yield = host_name_lookup() != DEFER;
3666 /* If a host name is known, check it and all its aliases. */
3668 if (sender_host_name)
3669 if ((f.helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3671 sender_helo_dnssec = sender_host_dnssec;
3672 HDEBUG(D_receive) debug_printf("matched host name\n");
3676 uschar **aliases = sender_host_aliases;
3678 if ((f.helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3680 sender_helo_dnssec = sender_host_dnssec;
3684 HDEBUG(D_receive) if (f.helo_verified)
3685 debug_printf("matched alias %s\n", *(--aliases));
3688 /* Final attempt: try a forward lookup of the helo name */
3690 if (!f.helo_verified)
3694 {.name = sender_helo_name, .address = NULL, .mx = MX_NONE, .next = NULL};
3696 {.request = US"*", .require = US""};
3698 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
3700 rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
3701 NULL, NULL, NULL, &d, NULL, NULL);
3702 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
3703 for (host_item * hh = &h; hh; hh = hh->next)
3704 if (Ustrcmp(hh->address, sender_host_address) == 0)
3706 f.helo_verified = TRUE;
3707 if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
3709 debug_printf("IP address for %s matches calling address\n"
3710 "Forward DNS security status: %sverified\n",
3711 sender_helo_name, sender_helo_dnssec ? "" : "un");
3717 if (!f.helo_verified) f.helo_verify_failed = TRUE; /* We've tried ... */
3724 /*************************************************
3725 * Send user response message *
3726 *************************************************/
3728 /* This function is passed a default response code and a user message. It calls
3729 smtp_message_code() to check and possibly modify the response code, and then
3730 calls smtp_respond() to transmit the response. I put this into a function
3731 just to avoid a lot of repetition.
3734 code the response code
3735 user_msg the user message
3741 smtp_user_msg(uschar *code, uschar *user_msg)
3744 smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
3745 smtp_respond(code, len, TRUE, user_msg);
3751 smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
3753 const uschar *set_id = NULL;
3756 /* Run the checking code, passing the remainder of the command line as
3757 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
3758 it as the only set numerical variable. The authenticator may set $auth<n>
3759 and also set other numeric variables. The $auth<n> variables are preferred
3760 nowadays; the numerical variables remain for backwards compatibility.
3762 Afterwards, have a go at expanding the set_id string, even if
3763 authentication failed - for bad passwords it can be useful to log the
3764 userid. On success, require set_id to expand and exist, and put it in
3765 authenticated_id. Save this in permanent store, as the working store gets
3766 reset at HELO, RSET, etc. */
3768 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
3770 expand_nlength[0] = 0; /* $0 contains nothing */
3772 rc = (au->info->servercode)(au, smtp_cmd_data);
3773 if (au->set_id) set_id = expand_string(au->set_id);
3774 expand_nmax = -1; /* Reset numeric variables */
3775 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
3777 /* The value of authenticated_id is stored in the spool file and printed in
3778 log lines. It must not contain binary zeros or newline characters. In
3779 normal use, it never will, but when playing around or testing, this error
3780 can (did) happen. To guard against this, ensure that the id contains only
3781 printing characters. */
3783 if (set_id) set_id = string_printing(set_id);
3785 /* For the non-OK cases, set up additional logging data if set_id
3789 set_id = set_id && *set_id
3790 ? string_sprintf(" (set_id=%s)", set_id) : US"";
3792 /* Switch on the result */
3797 if (!au->set_id || set_id) /* Complete success */
3799 if (set_id) authenticated_id = string_copy_perm(set_id, TRUE);
3800 sender_host_authenticated = au->name;
3801 sender_host_auth_pubname = au->public_name;
3802 authentication_failed = FALSE;
3803 authenticated_fail_id = NULL; /* Impossible to already be set? */
3806 (sender_host_address ? protocols : protocols_local)
3807 [pextend + pauthed + (tls_in.active.sock >= 0 ? pcrpted:0)];
3808 *s = *ss = US"235 Authentication succeeded";
3809 authenticated_by = au;
3813 /* Authentication succeeded, but we failed to expand the set_id string.
3814 Treat this as a temporary error. */
3816 auth_defer_msg = expand_string_message;
3820 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3821 *s = string_sprintf("435 Unable to authenticate at present%s",
3822 auth_defer_user_msg);
3823 *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
3824 set_id, auth_defer_msg);
3828 *s = *ss = US"501 Invalid base64 data";
3832 *s = *ss = US"501 Authentication cancelled";
3836 *s = *ss = US"553 Initial data not expected";
3840 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3841 *s = US"535 Incorrect authentication data";
3842 *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
3846 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3847 *s = US"435 Internal error";
3848 *ss = string_sprintf("435 Internal error%s: return %d from authentication "
3849 "check", set_id, rc);
3861 qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
3864 if (f.allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
3866 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3868 rd = Ustrlen(recipient) + 1;
3869 /* deconst ok as *recipient was not const */
3870 *recipient = US rewrite_address_qualify(*recipient, TRUE);
3873 smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
3875 log_write(L_smtp_syntax_error,
3876 LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
3877 tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
3885 smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
3888 f.smtp_in_quit = TRUE;
3889 incomplete_transaction_log(US"QUIT");
3891 && acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp)
3893 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3896 #ifdef EXIM_TCP_CORK
3897 (void) setsockopt(fileno(smtp_out), IPPROTO_TCP, EXIM_TCP_CORK, US &on, sizeof(on));
3901 smtp_respond(US"221", 3, TRUE, *user_msgp);
3903 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
3905 #ifdef SERVERSIDE_CLOSE_NOWAIT
3906 # ifndef DISABLE_TLS
3907 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
3910 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3911 smtp_get_connection_info());
3914 # ifndef DISABLE_TLS
3915 tls_close(NULL, TLS_SHUTDOWN_WAIT);
3918 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3919 smtp_get_connection_info());
3921 /* Pause, hoping client will FIN first so that they get the TIME_WAIT.
3922 The socket should become readble (though with no data) */
3925 int fd = fileno(smtp_in);
3927 struct timeval t_limit = {.tv_sec = 0, .tv_usec = 200*1000};
3931 (void) select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &t_limit);
3933 #endif /*!DAEMON_CLOSE_NOWAIT*/
3938 smtp_rset_handler(void)
3941 incomplete_transaction_log(US"RSET");
3942 smtp_printf("250 Reset OK\r\n", FALSE);
3943 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3948 expand_mailmax(const uschar * s)
3950 if (!(s = expand_cstring(s)))
3951 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand smtp_accept_max_per_connection");
3952 return *s ? Uatoi(s) : 0;
3955 /*************************************************
3956 * Initialize for SMTP incoming message *
3957 *************************************************/
3959 /* This function conducts the initial dialogue at the start of an incoming SMTP
3960 message, and builds a list of recipients. However, if the incoming message
3961 is part of a batch (-bS option) a separate function is called since it would
3962 be messy having tests splattered about all over this function. This function
3963 therefore handles the case where interaction is occurring. The input and output
3964 files are set up in smtp_in and smtp_out.
3966 The global recipients_list is set to point to a vector of recipient_item
3967 blocks, whose number is given by recipients_count. This is extended by the
3968 receive_add_recipient() function. The global variable sender_address is set to
3969 the sender's address. The yield is +1 if a message has been successfully
3970 started, 0 if a QUIT command was encountered or the connection was refused from
3971 the particular host, or -1 if the connection was lost.
3975 Returns: > 0 message successfully started (reached DATA)
3976 = 0 QUIT read or end of file reached or call refused
3981 smtp_setup_msg(void)
3984 BOOL toomany = FALSE;
3985 BOOL discarded = FALSE;
3986 BOOL last_was_rej_mail = FALSE;
3987 BOOL last_was_rcpt = FALSE;
3988 rmark reset_point = store_mark();
3990 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
3992 /* Reset for start of new message. We allow one RSET not to be counted as a
3993 nonmail command, for those MTAs that insist on sending it between every
3994 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
3995 TLS between messages (an Exim client may do this if it has messages queued up
3996 for the host). Note: we do NOT reset AUTH at this point. */
3998 reset_point = smtp_reset(reset_point);
3999 message_ended = END_NOTSTARTED;
4001 chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
4003 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
4004 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
4005 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
4007 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
4010 if (lwr_receive_getc != NULL)
4012 /* This should have already happened, but if we've gotten confused,
4013 force a reset here. */
4014 DEBUG(D_receive) debug_printf("WARNING: smtp_setup_msg had to restore receive functions to lowers\n");
4015 bdat_pop_receive_functions();
4018 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
4020 had_command_sigterm = 0;
4021 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
4023 /* Batched SMTP is handled in a different function. */
4025 if (smtp_batched_input) return smtp_setup_batch_msg();
4028 if (smtp_in) /* Avoid pure-ACKs while in cmd pingpong phase */
4029 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
4030 US &off, sizeof(off));
4033 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
4034 value. The values are 2 larger than the required yield of the function. */
4038 const uschar **argv;
4039 uschar *etrn_command;
4040 uschar *etrn_serialize_key;
4042 uschar *log_msg, *smtp_code;
4043 uschar *user_msg = NULL;
4044 uschar *recipient = NULL;
4045 uschar *hello = NULL;
4047 BOOL was_rej_mail = FALSE;
4048 BOOL was_rcpt = FALSE;
4049 void (*oldsignal)(int);
4051 int start, end, sender_domain, recipient_domain;
4054 uschar *orcpt = NULL;
4059 /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
4060 if ( tls_in.active.sock >= 0
4062 && tls_in.certificate_verified
4063 && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
4066 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
4068 for (auth_instance * au = auths; au; au = au->next)
4069 if (strcmpic(US"tls", au->driver_name) == 0)
4072 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4073 &user_msg, &log_msg)) != OK
4075 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4078 smtp_cmd_data = NULL;
4080 if (smtp_in_auth(au, &s, &ss) == OK)
4081 { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
4083 { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
4090 switch(smtp_read_command(
4091 #ifndef DISABLE_PIPE_CONNECT
4092 !fl.pipe_connect_acceptable,
4096 GETC_BUFFER_UNLIMITED))
4098 /* The AUTH command is not permitted to occur inside a transaction, and may
4099 occur successfully only once per connection. Actually, that isn't quite
4100 true. When TLS is started, all previous information about a connection must
4101 be discarded, so a new AUTH is permitted at that time.
4103 AUTH may only be used when it has been advertised. However, it seems that
4104 there are clients that send AUTH when it hasn't been advertised, some of
4105 them even doing this after HELO. And there are MTAs that accept this. Sigh.
4106 So there's a get-out that allows this to happen.
4108 AUTH is initially labelled as a "nonmail command" so that one occurrence
4109 doesn't get counted. We change the label here so that multiple failing
4110 AUTHS will eventually hit the nonmail threshold. */
4114 authentication_failed = TRUE;
4115 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
4117 if (!fl.auth_advertised && !f.allow_auth_unadvertised)
4119 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4120 US"AUTH command used when not advertised");
4123 if (sender_host_authenticated)
4125 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4126 US"already authenticated");
4131 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4132 US"not permitted in mail transaction");
4139 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4140 &user_msg, &log_msg)) != OK
4143 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4147 /* Find the name of the requested authentication mechanism. */
4150 for (; (c = *smtp_cmd_data) && !isspace(c); smtp_cmd_data++)
4151 if (!isalnum(c) && c != '-' && c != '_')
4153 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4154 US"invalid character in authentication mechanism name");
4158 /* If not at the end of the line, we must be at white space. Terminate the
4159 name and move the pointer on to any data that may be present. */
4163 *smtp_cmd_data++ = 0;
4164 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
4167 /* Search for an authentication mechanism which is configured for use
4168 as a server and which has been advertised (unless, sigh, allow_auth_
4169 unadvertised is set). */
4173 for (au = auths; au; au = au->next)
4174 if (strcmpic(s, au->public_name) == 0 && au->server &&
4175 (au->advertised || f.allow_auth_unadvertised))
4180 c = smtp_in_auth(au, &s, &ss);
4182 smtp_printf("%s\r\n", FALSE, s);
4184 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
4185 au->name, host_and_ident(FALSE), ss);
4188 done = synprot_error(L_smtp_protocol_error, 504, NULL,
4189 string_sprintf("%s authentication mechanism not supported", s));
4192 break; /* AUTH_CMD */
4194 /* The HELO/EHLO commands are permitted to appear in the middle of a
4195 session as well as at the beginning. They have the effect of a reset in
4196 addition to their other functions. Their absence at the start cannot be
4197 taken to be an error.
4201 If the EHLO command is not acceptable to the SMTP server, 501, 500,
4202 or 502 failure replies MUST be returned as appropriate. The SMTP
4203 server MUST stay in the same state after transmitting these replies
4204 that it was in before the EHLO was received.
4206 Therefore, we do not do the reset until after checking the command for
4207 acceptability. This change was made for Exim release 4.11. Previously
4208 it did the reset first. */
4221 HELO_EHLO: /* Common code for HELO and EHLO */
4222 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
4223 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
4225 /* Reject the HELO if its argument was invalid or non-existent. A
4226 successful check causes the argument to be saved in malloc store. */
4228 if (!check_helo(smtp_cmd_data))
4230 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
4232 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
4233 "invalid argument(s): %s", hello, host_and_ident(FALSE),
4234 *smtp_cmd_argument == 0 ? US"(no argument given)" :
4235 string_printing(smtp_cmd_argument));
4237 if (++synprot_error_count > smtp_max_synprot_errors)
4239 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4240 "syntax or protocol errors (last command was \"%s\", %s)",
4241 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
4242 string_from_gstring(s_connhad_log(NULL))
4250 /* If sender_host_unknown is true, we have got here via the -bs interface,
4251 not called from inetd. Otherwise, we are running an IP connection and the
4252 host address will be set. If the helo name is the primary name of this
4253 host and we haven't done a reverse lookup, force one now. If helo_verify_required
4254 is set, ensure that the HELO name matches the actual host. If helo_verify
4255 is set, do the same check, but softly. */
4257 if (!f.sender_host_unknown)
4259 BOOL old_helo_verified = f.helo_verified;
4260 uschar *p = smtp_cmd_data;
4262 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
4265 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
4266 because otherwise the log can be confusing. */
4268 if ( !sender_host_name
4269 && match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
4270 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL) == OK)
4271 (void)host_name_lookup();
4273 /* Rebuild the fullhost info to include the HELO name (and the real name
4274 if it was looked up.) */
4276 host_build_sender_fullhost(); /* Rebuild */
4277 set_process_info("handling%s incoming connection from %s",
4278 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
4280 /* Verify if configured. This doesn't give much security, but it does
4281 make some people happy to be able to do it. If helo_verify_required is set,
4282 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
4283 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
4284 now obsolescent, since the verification can now be requested selectively
4287 f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
4288 if (fl.helo_verify_required || fl.helo_verify)
4290 BOOL tempfail = !smtp_verify_helo();
4291 if (!f.helo_verified)
4293 if (fl.helo_verify_required)
4295 smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
4296 tempfail? 451 : 550, hello);
4297 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
4298 tempfail? "temporarily " : "",
4299 hello, sender_helo_name, host_and_ident(FALSE));
4300 f.helo_verified = old_helo_verified;
4301 break; /* End of HELO/EHLO processing */
4303 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
4304 "helo_try_verify_hosts\n", hello);
4310 /* set up SPF context */
4311 spf_conn_init(sender_helo_name, sender_host_address);
4314 /* Apply an ACL check if one is defined; afterwards, recheck
4315 synchronization in case the client started sending in a delay. */
4318 if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
4319 &user_msg, &log_msg)) != OK)
4321 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
4322 sender_helo_name = NULL;
4323 host_build_sender_fullhost(); /* Rebuild */
4326 #ifndef DISABLE_PIPE_CONNECT
4327 else if (!fl.pipe_connect_acceptable && !check_sync())
4329 else if (!check_sync())
4333 /* Generate an OK reply. The default string includes the ident if present,
4334 and also the IP address if present. Reflecting back the ident is intended
4335 as a deterrent to mail forgers. For maximum efficiency, and also because
4336 some broken systems expect each response to be in a single packet, arrange
4337 that the entire reply is sent in one write(). */
4339 fl.auth_advertised = FALSE;
4340 f.smtp_in_pipelining_advertised = FALSE;
4342 fl.tls_advertised = FALSE;
4344 fl.dsn_advertised = FALSE;
4346 fl.smtputf8_advertised = FALSE;
4349 /* Expand the per-connection message count limit option */
4350 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4352 smtp_code = US"250 "; /* Default response code plus space*/
4355 /* sender_host_name below will be tainted, so save on copy when we hit it */
4356 g = string_get_tainted(24, TRUE);
4357 g = string_fmt_append(g, "%.3s %s Hello %s%s%s",
4359 smtp_active_hostname,
4360 sender_ident ? sender_ident : US"",
4361 sender_ident ? US" at " : US"",
4362 sender_host_name ? sender_host_name : sender_helo_name);
4364 if (sender_host_address)
4365 g = string_fmt_append(g, " [%s]", sender_host_address);
4368 /* A user-supplied EHLO greeting may not contain more than one line. Note
4369 that the code returned by smtp_message_code() includes the terminating
4370 whitespace character. */
4376 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
4377 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
4378 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
4380 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
4381 "newlines: message truncated: %s", string_printing(s));
4384 g = string_cat(NULL, s);
4387 g = string_catn(g, US"\r\n", 2);
4389 /* If we received EHLO, we must create a multiline response which includes
4390 the functions supported. */
4396 /* I'm not entirely happy with this, as an MTA is supposed to check
4397 that it has enough room to accept a message of maximum size before
4398 it sends this. However, there seems little point in not sending it.
4399 The actual size check happens later at MAIL FROM time. By postponing it
4400 till then, VRFY and EXPN can be used after EHLO when space is short. */
4402 if (thismessage_size_limit > 0)
4403 g = string_fmt_append(g, "%.3s-SIZE %d\r\n", smtp_code,
4404 thismessage_size_limit);
4407 g = string_catn(g, smtp_code, 3);
4408 g = string_catn(g, US"-SIZE\r\n", 7);
4411 #ifdef EXPERIMENTAL_ESMTP_LIMITS
4412 if ( (smtp_mailcmd_max > 0 || recipients_max)
4413 && verify_check_host(&limits_advertise_hosts) == OK)
4415 g = string_fmt_append(g, "%.3s-LIMITS", smtp_code);
4416 if (smtp_mailcmd_max > 0)
4417 g = string_fmt_append(g, " MAILMAX=%d", smtp_mailcmd_max);
4419 g = string_fmt_append(g, " RCPTMAX=%d", recipients_max);
4420 g = string_catn(g, US"\r\n", 2);
4424 /* Exim does not do protocol conversion or data conversion. It is 8-bit
4425 clean; if it has an 8-bit character in its hand, it just sends it. It
4426 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
4427 However, some users want this option simply in order to stop MUAs
4428 mangling messages that contain top-bit-set characters. It is therefore
4429 provided as an option. */
4431 if (accept_8bitmime)
4433 g = string_catn(g, smtp_code, 3);
4434 g = string_catn(g, US"-8BITMIME\r\n", 11);
4437 /* Advertise DSN support if configured to do so. */
4438 if (verify_check_host(&dsn_advertise_hosts) != FAIL)
4440 g = string_catn(g, smtp_code, 3);
4441 g = string_catn(g, US"-DSN\r\n", 6);
4442 fl.dsn_advertised = TRUE;
4445 /* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
4446 permitted to issue them; a check is made when any host actually tries. */
4450 g = string_catn(g, smtp_code, 3);
4451 g = string_catn(g, US"-ETRN\r\n", 7);
4455 g = string_catn(g, smtp_code, 3);
4456 g = string_catn(g, US"-VRFY\r\n", 7);
4460 g = string_catn(g, smtp_code, 3);
4461 g = string_catn(g, US"-EXPN\r\n", 7);
4464 /* Exim is quite happy with pipelining, so let the other end know that
4465 it is safe to use it, unless advertising is disabled. */
4467 if ( f.pipelining_enable
4468 && verify_check_host(&pipelining_advertise_hosts) == OK)
4470 g = string_catn(g, smtp_code, 3);
4471 g = string_catn(g, US"-PIPELINING\r\n", 13);
4472 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
4473 f.smtp_in_pipelining_advertised = TRUE;
4475 #ifndef DISABLE_PIPE_CONNECT
4476 if (fl.pipe_connect_acceptable)
4478 f.smtp_in_early_pipe_advertised = TRUE;
4479 g = string_catn(g, smtp_code, 3);
4480 g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
4486 /* If any server authentication mechanisms are configured, advertise
4487 them if the current host is in auth_advertise_hosts. The problem with
4488 advertising always is that some clients then require users to
4489 authenticate (and aren't configurable otherwise) even though it may not
4490 be necessary (e.g. if the host is in host_accept_relay).
4492 RFC 2222 states that SASL mechanism names contain only upper case
4493 letters, so output the names in upper case, though we actually recognize
4494 them in either case in the AUTH command. */
4498 && !sender_host_authenticated
4500 && verify_check_host(&auth_advertise_hosts) == OK
4504 for (auth_instance * au = auths; au; au = au->next)
4506 au->advertised = FALSE;
4509 DEBUG(D_auth+D_expand) debug_printf_indent(
4510 "Evaluating advertise_condition for %s %s athenticator\n",
4511 au->name, au->public_name);
4512 if ( !au->advertise_condition
4513 || expand_check_condition(au->advertise_condition, au->name,
4520 g = string_catn(g, smtp_code, 3);
4521 g = string_catn(g, US"-AUTH", 5);
4523 fl.auth_advertised = TRUE;
4526 g = string_catn(g, US" ", 1);
4527 g = string_cat (g, au->public_name);
4528 while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
4529 au->advertised = TRUE;
4534 if (!first) g = string_catn(g, US"\r\n", 2);
4537 /* RFC 3030 CHUNKING */
4539 if (verify_check_host(&chunking_advertise_hosts) != FAIL)
4541 g = string_catn(g, smtp_code, 3);
4542 g = string_catn(g, US"-CHUNKING\r\n", 11);
4543 f.chunking_offered = TRUE;
4544 chunking_state = CHUNKING_OFFERED;
4547 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
4548 if it has been included in the binary, and the host matches
4549 tls_advertise_hosts. We must *not* advertise if we are already in a
4550 secure connection. */
4553 if (tls_in.active.sock < 0 &&
4554 verify_check_host(&tls_advertise_hosts) != FAIL)
4556 g = string_catn(g, smtp_code, 3);
4557 g = string_catn(g, US"-STARTTLS\r\n", 11);
4558 fl.tls_advertised = TRUE;
4562 #ifndef DISABLE_PRDR
4563 /* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
4566 g = string_catn(g, smtp_code, 3);
4567 g = string_catn(g, US"-PRDR\r\n", 7);
4572 if ( accept_8bitmime
4573 && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
4575 g = string_catn(g, smtp_code, 3);
4576 g = string_catn(g, US"-SMTPUTF8\r\n", 11);
4577 fl.smtputf8_advertised = TRUE;
4581 /* Finish off the multiline reply with one that is always available. */
4583 g = string_catn(g, smtp_code, 3);
4584 g = string_catn(g, US" HELP\r\n", 7);
4587 /* Terminate the string (for debug), write it, and note that HELO/EHLO
4591 if (tls_in.active.sock >= 0)
4592 (void)tls_write(NULL, g->s, g->ptr,
4593 # ifndef DISABLE_PIPE_CONNECT
4594 fl.pipe_connect_acceptable && pipeline_connect_sends());
4600 (void) fwrite(g->s, 1, g->ptr, smtp_out);
4606 (void) string_from_gstring(g);
4607 while ((cr = Ustrchr(g->s, '\r')) != NULL) /* lose CRs */
4608 memmove(cr, cr + 1, (g->ptr--) - (cr - g->s));
4609 debug_printf("SMTP>> %s", g->s);
4611 fl.helo_seen = TRUE;
4613 /* Reset the protocol and the state, abandoning any previous message. */
4615 (sender_host_address ? protocols : protocols_local)
4617 ? pextend + (sender_host_authenticated ? pauthed : 0)
4619 + (tls_in.active.sock >= 0 ? pcrpted : 0)
4621 cancel_cutthrough_connection(TRUE, US"sent EHLO response");
4622 reset_point = smtp_reset(reset_point);
4624 break; /* HELO/EHLO */
4627 /* The MAIL command requires an address as an operand. All we do
4628 here is to parse it for syntactic correctness. The form "<>" is
4629 a special case which converts into an empty string. The start/end
4630 pointers in the original are not used further for this address, as
4631 it is the canonical extracted address which is all that is kept. */
4635 smtp_mailcmd_count++; /* Count for limit and ratelimit */
4637 was_rej_mail = TRUE; /* Reset if accepted */
4638 env_mail_type_t * mail_args; /* Sanity check & validate args */
4641 if ( fl.helo_verify_required
4642 || verify_check_host(&hosts_require_helo) == OK)
4644 smtp_printf("503 HELO or EHLO required\r\n", FALSE);
4645 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
4646 "HELO/EHLO given", host_and_ident(FALSE));
4649 else if (smtp_mailcmd_max < 0)
4650 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4654 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4655 US"sender already given");
4659 if (!*smtp_cmd_data)
4661 done = synprot_error(L_smtp_protocol_error, 501, NULL,
4662 US"MAIL must have an address operand");
4666 /* Check to see if the limit for messages per connection would be
4667 exceeded by accepting further messages. */
4669 if (smtp_mailcmd_max > 0 && smtp_mailcmd_count > smtp_mailcmd_max)
4671 smtp_printf("421 too many messages in this connection\r\n", FALSE);
4672 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
4673 "messages in one connection", host_and_ident(TRUE));
4677 /* Reset for start of message - even if this is going to fail, we
4678 obviously need to throw away any previous data. */
4680 cancel_cutthrough_connection(TRUE, US"MAIL received");
4681 reset_point = smtp_reset(reset_point);
4683 sender_data = recipient_data = NULL;
4685 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
4687 if (fl.esmtp) for(;;)
4689 uschar *name, *value, *end;
4690 unsigned long int size;
4691 BOOL arg_error = FALSE;
4693 if (!extract_option(&name, &value)) break;
4695 for (mail_args = env_mail_type_list;
4696 mail_args->value != ENV_MAIL_OPT_NULL;
4699 if (strcmpic(name, mail_args->name) == 0)
4701 if (mail_args->need_value && strcmpic(value, US"") == 0)
4704 switch(mail_args->value)
4706 /* Handle SIZE= by reading the value. We don't do the check till later,
4707 in order to be able to log the sender address on failure. */
4708 case ENV_MAIL_OPT_SIZE:
4709 if (((size = Ustrtoul(value, &end, 10)), *end == 0))
4711 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
4713 message_size = (int)size;
4719 /* If this session was initiated with EHLO and accept_8bitmime is set,
4720 Exim will have indicated that it supports the BODY=8BITMIME option. In
4721 fact, it does not support this according to the RFCs, in that it does not
4722 take any special action for forwarding messages containing 8-bit
4723 characters. That is why accept_8bitmime is not the default setting, but
4724 some sites want the action that is provided. We recognize both "8BITMIME"
4725 and "7BIT" as body types, but take no action. */
4726 case ENV_MAIL_OPT_BODY:
4727 if (accept_8bitmime) {
4728 if (strcmpic(value, US"8BITMIME") == 0)
4730 else if (strcmpic(value, US"7BIT") == 0)
4735 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4736 US"invalid data for BODY");
4739 DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
4745 /* Handle the two DSN options, but only if configured to do so (which
4746 will have caused "DSN" to be given in the EHLO response). The code itself
4747 is included only if configured in at build time. */
4749 case ENV_MAIL_OPT_RET:
4750 if (fl.dsn_advertised)
4752 /* Check if RET has already been set */
4755 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4756 US"RET can be specified once only");
4759 dsn_ret = strcmpic(value, US"HDRS") == 0
4761 : strcmpic(value, US"FULL") == 0
4764 DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
4765 /* Check for invalid invalid value, and exit with error */
4768 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4769 US"Value for RET is invalid");
4774 case ENV_MAIL_OPT_ENVID:
4775 if (fl.dsn_advertised)
4777 /* Check if the dsn envid has been already set */
4780 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4781 US"ENVID can be specified once only");
4784 dsn_envid = string_copy(value);
4785 DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
4789 /* Handle the AUTH extension. If the value given is not "<>" and either
4790 the ACL says "yes" or there is no ACL but the sending host is
4791 authenticated, we set it up as the authenticated sender. However, if the
4792 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
4793 the condition is met. The value of AUTH is an xtext, which means that +,
4794 = and cntrl chars are coded in hex; however "<>" is unaffected by this
4796 case ENV_MAIL_OPT_AUTH:
4797 if (Ustrcmp(value, "<>") != 0)
4802 if (auth_xtextdecode(value, &authenticated_sender) < 0)
4804 /* Put back terminator overrides for error message */
4807 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4808 US"invalid data for AUTH");
4811 if (!acl_smtp_mailauth)
4813 ignore_msg = US"client not authenticated";
4814 rc = sender_host_authenticated ? OK : FAIL;
4818 ignore_msg = US"rejected by ACL";
4819 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
4820 &user_msg, &log_msg);
4826 if (authenticated_by == NULL ||
4827 authenticated_by->mail_auth_condition == NULL ||
4828 expand_check_condition(authenticated_by->mail_auth_condition,
4829 authenticated_by->name, US"authenticator"))
4830 break; /* Accept the AUTH */
4832 ignore_msg = US"server_mail_auth_condition failed";
4833 if (authenticated_id != NULL)
4834 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
4835 ignore_msg, authenticated_id);
4840 authenticated_sender = NULL;
4841 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
4842 value, host_and_ident(TRUE), ignore_msg);
4845 /* Should only get DEFER or ERROR here. Put back terminator
4846 overrides for error message */
4851 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
4858 #ifndef DISABLE_PRDR
4859 case ENV_MAIL_OPT_PRDR:
4861 prdr_requested = TRUE;
4866 case ENV_MAIL_OPT_UTF8:
4867 if (!fl.smtputf8_advertised)
4869 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4870 US"SMTPUTF8 used when not advertised");
4874 DEBUG(D_receive) debug_printf("smtputf8 requested\n");
4875 message_smtputf8 = allow_utf8_domains = TRUE;
4876 if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
4878 int old_pool = store_pool;
4879 store_pool = POOL_PERM;
4880 received_protocol = string_sprintf("utf8%s", received_protocol);
4881 store_pool = old_pool;
4886 /* No valid option. Stick back the terminator characters and break
4887 the loop. Do the name-terminator second as extract_option sets
4888 value==name when it found no equal-sign.
4889 An error for a malformed address will occur. */
4890 case ENV_MAIL_OPT_NULL:
4898 /* Break out of for loop if switch() had bad argument or
4899 when start of the email address is reached */
4900 if (arg_error) break;
4903 /* If we have passed the threshold for rate limiting, apply the current
4904 delay, and update it for next time, provided this is a limited host. */
4906 if (smtp_mailcmd_count > smtp_rlm_threshold &&
4907 verify_check_host(&smtp_ratelimit_hosts) == OK)
4909 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
4910 smtp_delay_mail/1000.0);
4911 millisleep((int)smtp_delay_mail);
4912 smtp_delay_mail *= smtp_rlm_factor;
4913 if (smtp_delay_mail > (double)smtp_rlm_limit)
4914 smtp_delay_mail = (double)smtp_rlm_limit;
4917 /* Now extract the address, first applying any SMTP-time rewriting. The
4918 TRUE flag allows "<>" as a sender address. */
4920 raw_sender = rewrite_existflags & rewrite_smtp
4921 /* deconst ok as smtp_cmd_data was not const */
4922 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
4923 global_rewrite_rules)
4927 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
4932 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
4936 sender_address = raw_sender;
4938 /* If there is a configured size limit for mail, check that this message
4939 doesn't exceed it. The check is postponed to this point so that the sender
4942 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
4944 smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
4945 log_write(L_size_reject,
4946 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
4947 "message too big: size%s=%d max=%d",
4949 host_and_ident(TRUE),
4950 (message_size == INT_MAX)? ">" : "",
4952 thismessage_size_limit);
4953 sender_address = NULL;
4957 /* Check there is enough space on the disk unless configured not to.
4958 When smtp_check_spool_space is set, the check is for thismessage_size_limit
4959 plus the current message - i.e. we accept the message only if it won't
4960 reduce the space below the threshold. Add 5000 to the size to allow for
4961 overheads such as the Received: line and storing of recipients, etc.
4962 By putting the check here, even when SIZE is not given, it allow VRFY
4963 and EXPN etc. to be used when space is short. */
4965 if (!receive_check_fs(
4966 smtp_check_spool_space && message_size >= 0
4967 ? message_size + 5000 : 0))
4969 smtp_printf("452 Space shortage, please try later\r\n", FALSE);
4970 sender_address = NULL;
4974 /* If sender_address is unqualified, reject it, unless this is a locally
4975 generated message, or the sending host or net is permitted to send
4976 unqualified addresses - typically local machines behaving as MUAs -
4977 in which case just qualify the address. The flag is set above at the start
4978 of the SMTP connection. */
4980 if (!sender_domain && *sender_address)
4981 if (f.allow_unqualified_sender)
4983 sender_domain = Ustrlen(sender_address) + 1;
4984 /* deconst ok as sender_address was not const */
4985 sender_address = US rewrite_address_qualify(sender_address, FALSE);
4986 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
4991 smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
4993 log_write(L_smtp_syntax_error,
4994 LOG_MAIN|LOG_REJECT,
4995 "unqualified sender rejected: <%s> %s%s",
4997 host_and_ident(TRUE),
4999 sender_address = NULL;
5003 /* Apply an ACL check if one is defined, before responding. Afterwards,
5004 when pipelining is not advertised, do another sync check in case the ACL
5005 delayed and the client started sending in the meantime. */
5009 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
5010 if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
5016 if (rc == OK || rc == DISCARD)
5018 BOOL more = pipeline_response();
5021 smtp_printf("%s%s%s", more, US"250 OK",
5022 #ifndef DISABLE_PRDR
5023 prdr_requested ? US", PRDR Requested" : US"",
5030 #ifndef DISABLE_PRDR
5032 user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
5034 smtp_user_msg(US"250", user_msg);
5036 smtp_delay_rcpt = smtp_rlr_base;
5037 f.recipients_discarded = (rc == DISCARD);
5038 was_rej_mail = FALSE;
5042 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
5043 sender_address = NULL;
5048 /* The RCPT command requires an address as an operand. There may be any
5049 number of RCPT commands, specifying multiple recipients. We build them all
5050 into a data structure. The start/end values given by parse_extract_address
5051 are not used, as we keep only the extracted address. */
5055 /* We got really to many recipients. A check against configured
5056 limits is done later */
5057 if (rcpt_count < 0 || rcpt_count >= INT_MAX/2)
5058 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Too many recipients: %d", rcpt_count);
5060 was_rcpt = fl.rcpt_in_progress = TRUE;
5062 /* There must be a sender address; if the sender was rejected and
5063 pipelining was advertised, we assume the client was pipelining, and do not
5064 count this as a protocol error. Reset was_rej_mail so that further RCPTs
5065 get the same treatment. */
5067 if (sender_address == NULL)
5069 if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
5071 smtp_printf("503 sender not yet given\r\n", FALSE);
5072 was_rej_mail = TRUE;
5076 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5077 US"sender not yet given");
5078 was_rcpt = FALSE; /* Not a valid RCPT */
5084 /* Check for an operand */
5086 if (smtp_cmd_data[0] == 0)
5088 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5089 US"RCPT must have an address operand");
5094 /* Set the DSN flags orcpt and dsn_flags from the session*/
5098 if (fl.esmtp) for(;;)
5100 uschar *name, *value;
5102 if (!extract_option(&name, &value))
5105 if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
5107 /* Check whether orcpt has been already set */
5110 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5111 US"ORCPT can be specified once only");
5114 orcpt = string_copy(value);
5115 DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
5118 else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
5120 /* Check if the notify flags have been already set */
5123 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5124 US"NOTIFY can be specified once only");
5127 if (strcmpic(value, US"NEVER") == 0)
5128 dsn_flags |= rf_notify_never;
5135 while (*pp != 0 && *pp != ',') pp++;
5136 if (*pp == ',') *pp++ = 0;
5137 if (strcmpic(p, US"SUCCESS") == 0)
5139 DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
5140 dsn_flags |= rf_notify_success;
5142 else if (strcmpic(p, US"FAILURE") == 0)
5144 DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
5145 dsn_flags |= rf_notify_failure;
5147 else if (strcmpic(p, US"DELAY") == 0)
5149 DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
5150 dsn_flags |= rf_notify_delay;
5154 /* Catch any strange values */
5155 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5156 US"Invalid value for NOTIFY parameter");
5161 DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
5165 /* Unknown option. Stick back the terminator characters and break
5166 the loop. An error for a malformed address will occur. */
5170 DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
5177 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
5178 as a recipient address */
5180 recipient = rewrite_existflags & rewrite_smtp
5181 /* deconst ok as smtp_cmd_data was not const */
5182 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
5183 global_rewrite_rules)
5186 if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
5187 &recipient_domain, FALSE)))
5189 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
5194 /* If the recipient address is unqualified, reject it, unless this is a
5195 locally generated message. However, unqualified addresses are permitted
5196 from a configured list of hosts and nets - typically when behaving as
5197 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
5198 really. The flag is set at the start of the SMTP connection.
5200 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
5201 assumed this meant "reserved local part", but the revision of RFC 821 and
5202 friends now makes it absolutely clear that it means *mailbox*. Consequently
5203 we must always qualify this address, regardless. */
5205 if (!recipient_domain)
5206 if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
5213 /* Check maximum allowed */
5215 if (rcpt_count+1 < 0 || rcpt_count > recipients_max && recipients_max > 0)
5217 if (recipients_max_reject)
5220 smtp_printf("552 too many recipients\r\n", FALSE);
5222 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
5223 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
5228 smtp_printf("452 too many recipients\r\n", FALSE);
5230 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
5231 "temporarily rejected: sender=<%s> %s", sender_address,
5232 host_and_ident(TRUE));
5239 /* If we have passed the threshold for rate limiting, apply the current
5240 delay, and update it for next time, provided this is a limited host. */
5242 if (rcpt_count > smtp_rlr_threshold &&
5243 verify_check_host(&smtp_ratelimit_hosts) == OK)
5245 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
5246 smtp_delay_rcpt/1000.0);
5247 millisleep((int)smtp_delay_rcpt);
5248 smtp_delay_rcpt *= smtp_rlr_factor;
5249 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
5250 smtp_delay_rcpt = (double)smtp_rlr_limit;
5253 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
5254 for them. Otherwise, check the access control list for this recipient. As
5255 there may be a delay in this, re-check for a synchronization error
5256 afterwards, unless pipelining was advertised. */
5258 if (f.recipients_discarded)
5261 if ( (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
5263 && !f.smtp_in_pipelining_advertised && !check_sync())
5266 /* The ACL was happy */
5270 BOOL more = pipeline_response();
5273 smtp_user_msg(US"250", user_msg);
5275 smtp_printf("250 Accepted\r\n", more);
5276 receive_add_recipient(recipient, -1);
5278 /* Set the dsn flags in the recipients_list */
5279 recipients_list[recipients_count-1].orcpt = orcpt;
5280 recipients_list[recipients_count-1].dsn_flags = dsn_flags;
5282 /* DEBUG(D_receive) debug_printf("DSN: orcpt: %s flags: %d\n",
5283 recipients_list[recipients_count-1].orcpt,
5284 recipients_list[recipients_count-1].dsn_flags); */
5287 /* The recipient was discarded */
5289 else if (rc == DISCARD)
5292 smtp_user_msg(US"250", user_msg);
5294 smtp_printf("250 Accepted\r\n", FALSE);
5297 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
5298 "discarded by %s ACL%s%s", host_and_ident(TRUE),
5299 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
5300 smtp_cmd_argument, f.recipients_discarded ? "MAIL" : "RCPT",
5301 log_msg ? US": " : US"", log_msg ? log_msg : US"");
5304 /* Either the ACL failed the address, or it was deferred. */
5308 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
5309 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
5314 /* The DATA command is legal only if it follows successful MAIL FROM
5315 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
5316 not counted as a protocol error if it follows RCPT (which must have been
5317 rejected if there are no recipients.) This function is complete when a
5318 valid DATA command is encountered.
5320 Note concerning the code used: RFC 2821 says this:
5322 - If there was no MAIL, or no RCPT, command, or all such commands
5323 were rejected, the server MAY return a "command out of sequence"
5324 (503) or "no valid recipients" (554) reply in response to the
5327 The example in the pipelining RFC 2920 uses 554, but I use 503 here
5328 because it is the same whether pipelining is in use or not.
5330 If all the RCPT commands that precede DATA provoked the same error message
5331 (often indicating some kind of system error), it is helpful to include it
5332 with the DATA rejection (an idea suggested by Tony Finch). */
5339 if (chunking_state != CHUNKING_OFFERED)
5341 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5342 US"BDAT command used when CHUNKING not advertised");
5346 /* grab size, endmarker */
5348 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
5350 done = synprot_error(L_smtp_protocol_error, 501, NULL,
5351 US"missing size for BDAT command");
5354 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
5355 ? CHUNKING_LAST : CHUNKING_ACTIVE;
5356 chunking_data_left = chunking_datasize;
5357 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
5358 (int)chunking_state, chunking_data_left);
5360 f.bdat_readers_wanted = TRUE; /* FIXME: redundant vs chunking_state? */
5369 f.bdat_readers_wanted = FALSE;
5371 DATA_BDAT: /* Common code for DATA and BDAT */
5372 #ifndef DISABLE_PIPE_CONNECT
5373 fl.pipe_connect_acceptable = FALSE;
5375 if (!discarded && recipients_count <= 0)
5377 if (fl.rcpt_smtp_response_same && rcpt_smtp_response != NULL)
5379 uschar *code = US"503";
5380 int len = Ustrlen(rcpt_smtp_response);
5381 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
5383 /* Responses from smtp_printf() will have \r\n on the end */
5384 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
5385 rcpt_smtp_response[len-2] = 0;
5386 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
5388 if (f.smtp_in_pipelining_advertised && last_was_rcpt)
5389 smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
5390 smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]);
5392 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5393 smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA
5394 ? US"valid RCPT command must precede DATA"
5395 : US"valid RCPT command must precede BDAT");
5397 if (chunking_state > CHUNKING_OFFERED)
5399 bdat_push_receive_functions();
5405 if (toomany && recipients_max_reject)
5407 sender_address = NULL; /* This will allow a new MAIL without RSET */
5408 sender_address_unrewritten = NULL;
5409 smtp_printf("554 Too many recipients\r\n", FALSE);
5411 if (chunking_state > CHUNKING_OFFERED)
5413 bdat_push_receive_functions();
5419 if (chunking_state > CHUNKING_OFFERED)
5420 rc = OK; /* No predata ACL or go-ahead output for BDAT */
5423 /* If there is an ACL, re-check the synchronization afterwards, since the
5424 ACL may have delayed. To handle cutthrough delivery enforce a dummy call
5425 to get the DATA command sent. */
5427 if (acl_smtp_predata == NULL && cutthrough.cctx.sock < 0)
5431 uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
5432 f.enable_dollar_recipients = TRUE;
5433 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
5435 f.enable_dollar_recipients = FALSE;
5436 if (rc == OK && !check_sync())
5440 { /* Either the ACL failed the address, or it was deferred. */
5441 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
5447 smtp_user_msg(US"354", user_msg);
5450 "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
5453 if (f.bdat_readers_wanted)
5454 bdat_push_receive_functions();
5457 if (smtp_in) /* all ACKs needed to ramp window up for bulk data */
5458 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
5459 US &on, sizeof(on));
5462 message_ended = END_NOTENDED; /* Indicate in middle of data */
5473 if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
5474 &start, &end, &recipient_domain, FALSE)))
5476 smtp_printf("501 %s\r\n", FALSE, errmess);
5480 if (!recipient_domain)
5481 if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
5485 if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
5486 &user_msg, &log_msg)) != OK)
5487 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
5491 address_item * addr = deliver_make_addr(address, FALSE);
5493 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
5494 -1, -1, NULL, NULL, NULL))
5497 s = string_sprintf("250 <%s> is deliverable", address);
5501 s = (addr->user_message != NULL)?
5502 string_sprintf("451 <%s> %s", address, addr->user_message) :
5503 string_sprintf("451 Cannot resolve <%s> at this time", address);
5507 s = (addr->user_message != NULL)?
5508 string_sprintf("550 <%s> %s", address, addr->user_message) :
5509 string_sprintf("550 <%s> is not deliverable", address);
5510 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
5511 smtp_cmd_argument, host_and_ident(TRUE));
5515 smtp_printf("%s\r\n", FALSE, s);
5523 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
5525 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
5528 BOOL save_log_testing_mode = f.log_testing_mode;
5529 f.address_test_mode = f.log_testing_mode = TRUE;
5530 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
5531 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
5533 f.address_test_mode = FALSE;
5534 f.log_testing_mode = save_log_testing_mode; /* true for -bh */
5543 if (!fl.tls_advertised)
5545 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5546 US"STARTTLS command used when not advertised");
5550 /* Apply an ACL check if one is defined */
5552 if ( acl_smtp_starttls
5553 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
5554 &user_msg, &log_msg)) != OK
5557 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
5561 /* RFC 2487 is not clear on when this command may be sent, though it
5562 does state that all information previously obtained from the client
5563 must be discarded if a TLS session is started. It seems reasonable to
5564 do an implied RSET when STARTTLS is received. */
5566 incomplete_transaction_log(US"STARTTLS");
5567 cancel_cutthrough_connection(TRUE, US"STARTTLS received");
5568 reset_point = smtp_reset(reset_point);
5570 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
5572 /* There's an attack where more data is read in past the STARTTLS command
5573 before TLS is negotiated, then assumed to be part of the secure session
5574 when used afterwards; we use segregated input buffers, so are not
5575 vulnerable, but we want to note when it happens and, for sheer paranoia,
5576 ensure that the buffer is "wiped".
5577 Pipelining sync checks will normally have protected us too, unless disabled
5578 by configuration. */
5580 if (receive_smtp_buffered())
5583 debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
5584 if (tls_in.active.sock < 0)
5585 smtp_inend = smtp_inptr = smtp_inbuffer;
5586 /* and if TLS is already active, tls_server_start() should fail */
5589 /* There is nothing we value in the input buffer and if TLS is successfully
5590 negotiated, we won't use this buffer again; if TLS fails, we'll just read
5591 fresh content into it. The buffer contains arbitrary content from an
5592 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
5593 It seems safest to just wipe away the content rather than leave it as a
5594 target to jump to. */
5596 memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);
5598 /* Attempt to start up a TLS session, and if successful, discard all
5599 knowledge that was obtained previously. At least, that's what the RFC says,
5600 and that's what happens by default. However, in order to work round YAEB,
5601 there is an option to remember the esmtp state. Sigh.
5603 We must allow for an extra EHLO command and an extra AUTH command after
5604 STARTTLS that don't add to the nonmail command count. */
5607 if ((rc = tls_server_start(&s)) == OK)
5609 if (!tls_remember_esmtp)
5610 fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
5611 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
5612 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
5613 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
5614 if (sender_helo_name)
5616 sender_helo_name = NULL;
5617 host_build_sender_fullhost(); /* Rebuild */
5618 set_process_info("handling incoming TLS connection from %s",
5619 host_and_ident(FALSE));
5622 (sender_host_address ? protocols : protocols_local)
5624 ? pextend + (sender_host_authenticated ? pauthed : 0)
5626 + (tls_in.active.sock >= 0 ? pcrpted : 0)
5629 sender_host_auth_pubname = sender_host_authenticated = NULL;
5630 authenticated_id = NULL;
5631 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
5632 DEBUG(D_tls) debug_printf("TLS active\n");
5633 break; /* Successful STARTTLS */
5636 (void) smtp_log_tls_fail(s);
5638 /* Some local configuration problem was discovered before actually trying
5639 to do a TLS handshake; give a temporary error. */
5643 smtp_printf("454 TLS currently unavailable\r\n", FALSE);
5647 /* Hard failure. Reject everything except QUIT or closed connection. One
5648 cause for failure is a nested STARTTLS, in which case tls_in.active remains
5649 set, but we must still reject all incoming commands. Another is a handshake
5650 failure - and there may some encrypted data still in the pipe to us, which we
5651 see as garbage commands. */
5653 DEBUG(D_tls) debug_printf("TLS failed to start\n");
5654 while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
5657 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
5658 smtp_get_connection_info());
5659 smtp_notquit_exit(US"tls-failed", NULL, NULL);
5663 /* It is perhaps arguable as to which exit ACL should be called here,
5664 but as it is probably a situation that almost never arises, it
5665 probably doesn't matter. We choose to call the real QUIT ACL, which in
5666 some sense is perhaps "right". */
5669 f.smtp_in_quit = TRUE;
5672 && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
5673 &log_msg)) == ERROR))
5674 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
5677 smtp_respond(US"221", 3, TRUE, user_msg);
5679 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
5680 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
5681 smtp_get_connection_info());
5686 smtp_printf("554 Security failure\r\n", FALSE);
5689 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
5694 /* The ACL for QUIT is provided for gathering statistical information or
5695 similar; it does not affect the response code, but it can supply a custom
5699 smtp_quit_handler(&user_msg, &log_msg);
5705 smtp_rset_handler();
5706 cancel_cutthrough_connection(TRUE, US"RSET received");
5707 reset_point = smtp_reset(reset_point);
5714 smtp_printf("250 OK\r\n", FALSE);
5718 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
5719 used, a check will be done for permitted hosts. Show STARTTLS only if not
5720 already in a TLS session and if it would be advertised in the EHLO
5725 smtp_printf("214-Commands supported:\r\n", TRUE);
5729 Ustrcat(buffer, US" AUTH");
5731 if (tls_in.active.sock < 0 &&
5732 verify_check_host(&tls_advertise_hosts) != FAIL)
5733 Ustrcat(buffer, US" STARTTLS");
5735 Ustrcat(buffer, US" HELO EHLO MAIL RCPT DATA BDAT");
5736 Ustrcat(buffer, US" NOOP QUIT RSET HELP");
5737 if (acl_smtp_etrn) Ustrcat(buffer, US" ETRN");
5738 if (acl_smtp_expn) Ustrcat(buffer, US" EXPN");
5739 if (acl_smtp_vrfy) Ustrcat(buffer, US" VRFY");
5740 smtp_printf("214%s\r\n", FALSE, buffer);
5746 incomplete_transaction_log(US"connection lost");
5747 smtp_notquit_exit(US"connection-lost", US"421",
5748 US"%s lost input connection", smtp_active_hostname);
5750 /* Don't log by default unless in the middle of a message, as some mailers
5751 just drop the call rather than sending QUIT, and it clutters up the logs.
5754 if (sender_address || recipients_count > 0)
5755 log_write(L_lost_incoming_connection, LOG_MAIN,
5756 "unexpected %s while reading SMTP command from %s%s%s D=%s",
5757 f.sender_host_unknown ? "EOF" : "disconnection",
5758 f.tcp_in_fastopen_logged
5761 ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
5763 host_and_ident(FALSE), smtp_read_error,
5764 string_timesince(&smtp_connection_start)
5768 log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
5769 smtp_get_connection_info(),
5770 f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
5772 string_timesince(&smtp_connection_start)
5783 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5784 US"ETRN is not permitted inside a transaction");
5788 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
5789 host_and_ident(FALSE));
5791 if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
5792 &user_msg, &log_msg)) != OK)
5794 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
5798 /* Compute the serialization key for this command. */
5800 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
5802 /* If a command has been specified for running as a result of ETRN, we
5803 permit any argument to ETRN. If not, only the # standard form is permitted,
5804 since that is strictly the only kind of ETRN that can be implemented
5805 according to the RFC. */
5807 if (smtp_etrn_command)
5811 etrn_command = smtp_etrn_command;
5812 deliver_domain = smtp_cmd_data;
5813 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
5814 US"ETRN processing", &error);
5815 deliver_domain = NULL;
5818 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
5820 smtp_printf("458 Internal failure\r\n", FALSE);
5825 /* Else set up to call Exim with the -R option. */
5829 if (*smtp_cmd_data++ != '#')
5831 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5832 US"argument must begin with #");
5835 etrn_command = US"exim -R";
5836 argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
5837 *queue_name ? 4 : 2,
5838 US"-R", smtp_cmd_data,
5839 US"-MCG", queue_name);
5842 /* If we are host-testing, don't actually do anything. */
5848 debug_printf("ETRN command is: %s\n", etrn_command);
5849 debug_printf("ETRN command execution skipped\n");
5851 if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
5852 else smtp_user_msg(US"250", user_msg);
5857 /* If ETRN queue runs are to be serialized, check the database to
5858 ensure one isn't already running. */
5860 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
5862 smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
5866 /* Fork a child process and run the command. We don't want to have to
5867 wait for the process at any point, so set SIGCHLD to SIG_IGN before
5868 forking. It should be set that way anyway for external incoming SMTP,
5869 but we save and restore to be tidy. If serialization is required, we
5870 actually run the command in yet another process, so we can wait for it
5871 to complete and then remove the serialization lock. */
5873 oldsignal = signal(SIGCHLD, SIG_IGN);
5875 if ((pid = exim_fork(US"etrn-command")) == 0)
5877 smtp_input = FALSE; /* This process is not associated with the */
5878 (void)fclose(smtp_in); /* SMTP call any more. */
5879 (void)fclose(smtp_out);
5881 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
5883 /* If not serializing, do the exec right away. Otherwise, fork down
5884 into another process. */
5886 if ( !smtp_etrn_serialize
5887 || (pid = exim_fork(US"etrn-serialised-command")) == 0)
5889 DEBUG(D_exec) debug_print_argv(argv);
5890 exim_nullstd(); /* Ensure std{in,out,err} exist */
5891 execv(CS argv[0], (char *const *)argv);
5892 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
5893 etrn_command, strerror(errno));
5894 _exit(EXIT_FAILURE); /* paranoia */
5897 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
5898 is, we are in the first subprocess, after forking again. All we can do
5899 for a failing fork is to log it. Otherwise, wait for the 2nd process to
5900 complete, before removing the serialization. */
5903 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
5904 "failed: %s", strerror(errno));
5908 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
5910 (void)wait(&status);
5911 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
5915 enq_end(etrn_serialize_key);
5916 exim_underbar_exit(EXIT_SUCCESS);
5919 /* Back in the top level SMTP process. Check that we started a subprocess
5920 and restore the signal state. */
5924 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
5926 smtp_printf("458 Unable to fork process\r\n", FALSE);
5927 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
5931 smtp_printf("250 OK\r\n", FALSE);
5933 smtp_user_msg(US"250", user_msg);
5935 signal(SIGCHLD, oldsignal);
5940 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5941 US"unexpected argument data");
5945 /* This currently happens only for NULLs, but could be extended. */
5948 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
5949 US"NUL character(s) present (shown as '?')");
5950 smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
5957 if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
5958 smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
5959 c = smtp_inend - smtp_inptr;
5960 if (c > 150) c = 150; /* limit logged amount */
5962 incomplete_transaction_log(US"sync failure");
5963 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
5964 "(next input sent too soon: pipelining was%s advertised): "
5965 "rejected \"%s\" %s next input=\"%s\"",
5966 f.smtp_in_pipelining_advertised ? "" : " not",
5967 smtp_cmd_buffer, host_and_ident(TRUE),
5968 string_printing(smtp_inptr));
5969 smtp_notquit_exit(US"synchronization-error", US"554",
5970 US"SMTP synchronization error");
5971 done = 1; /* Pretend eof - drops connection */
5975 case TOO_MANY_NONMAIL_CMD:
5976 s = smtp_cmd_buffer;
5977 while (*s != 0 && !isspace(*s)) s++;
5978 incomplete_transaction_log(US"too many non-mail commands");
5979 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
5980 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
5981 (int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
5982 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
5983 done = 1; /* Pretend eof - drops connection */
5986 #ifdef SUPPORT_PROXY
5987 case PROXY_FAIL_IGNORE_CMD:
5988 smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
5993 if (unknown_command_count++ >= smtp_max_unknown_commands)
5995 log_write(L_smtp_syntax_error, LOG_MAIN,
5996 "SMTP syntax error in \"%s\" %s %s",
5997 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
5998 US"unrecognized command");
5999 incomplete_transaction_log(US"unrecognized command");
6000 smtp_notquit_exit(US"bad-commands", US"500",
6001 US"Too many unrecognized commands");
6003 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
6004 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
6005 string_printing(smtp_cmd_buffer));
6008 done = synprot_error(L_smtp_syntax_error, 500, NULL,
6009 US"unrecognized command");
6013 /* This label is used by goto's inside loops that want to break out to
6014 the end of the command-processing loop. */
6017 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
6018 last_was_rcpt = was_rcpt; /* protocol error handling */
6022 return done - 2; /* Convert yield values */
6028 authres_smtpauth(gstring * g)
6030 if (!sender_host_authenticated)
6033 g = string_append(g, 2, US";\n\tauth=pass (", sender_host_auth_pubname);
6035 if (Ustrcmp(sender_host_auth_pubname, "tls") == 0)
6036 g = authenticated_id
6037 ? string_append(g, 2, US") x509.auth=", authenticated_id)
6038 : string_cat(g, US") reason=x509.auth");
6040 g = authenticated_id
6041 ? string_append(g, 2, US") smtp.auth=", authenticated_id)
6042 : string_cat(g, US", no id saved)");
6044 if (authenticated_sender)
6045 g = string_append(g, 2, US" smtp.mailfrom=", authenticated_sender);
6053 /* End of smtp_in.c */