1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2016 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* A number of functions for driving outgoing SMTP calls. */
12 #include "transports/smtp.h"
16 /*************************************************
17 * Find an outgoing interface *
18 *************************************************/
20 /* This function is called from the smtp transport and also from the callout
21 code in verify.c. Its job is to expand a string to get a list of interfaces,
22 and choose a suitable one (IPv4 or IPv6) for the outgoing address.
25 istring string interface setting, may be NULL, meaning "any", in
26 which case the function does nothing
27 host_af AF_INET or AF_INET6 for the outgoing IP address
28 addr the mail address being handled (for setting errors)
29 interface point this to the interface
30 msg to add to any error message
32 Returns: TRUE on success, FALSE on failure, with error message
33 set in addr and transport_return set to PANIC
37 smtp_get_interface(uschar *istring, int host_af, address_item *addr,
38 uschar **interface, uschar *msg)
40 const uschar * expint;
44 if (!istring) return TRUE;
46 if (!(expint = expand_string(istring)))
48 if (expand_string_forcedfail) return TRUE;
49 addr->transport_return = PANIC;
50 addr->message = string_sprintf("failed to expand \"interface\" "
51 "option for %s: %s", msg, expand_string_message);
55 while (isspace(*expint)) expint++;
56 if (*expint == 0) return TRUE;
58 while ((iface = string_nextinlist(&expint, &sep, big_buffer,
61 if (string_is_ip_address(iface, NULL) == 0)
63 addr->transport_return = PANIC;
64 addr->message = string_sprintf("\"%s\" is not a valid IP "
65 "address for the \"interface\" option for %s",
70 if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af)
74 if (iface) *interface = string_copy(iface);
80 /*************************************************
81 * Find an outgoing port *
82 *************************************************/
84 /* This function is called from the smtp transport and also from the callout
85 code in verify.c. Its job is to find a port number. Note that getservbyname()
86 produces the number in network byte order.
89 rstring raw (unexpanded) string representation of the port
90 addr the mail address being handled (for setting errors)
91 port stick the port in here
92 msg for adding to error message
94 Returns: TRUE on success, FALSE on failure, with error message set
95 in addr, and transport_return set to PANIC
99 smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg)
101 uschar *pstring = expand_string(rstring);
105 addr->transport_return = PANIC;
106 addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) "
107 "for %s: %s", rstring, msg, expand_string_message);
111 if (isdigit(*pstring))
114 *port = Ustrtol(pstring, &end, 0);
115 if (end != pstring + Ustrlen(pstring))
117 addr->transport_return = PANIC;
118 addr->message = string_sprintf("invalid port number for %s: %s", msg,
126 struct servent *smtp_service = getservbyname(CS pstring, "tcp");
129 addr->transport_return = PANIC;
130 addr->message = string_sprintf("TCP port \"%s\" is not defined for %s",
134 *port = ntohs(smtp_service->s_port);
143 /* Arguments as for smtp_connect(), plus
144 early_data if non-NULL, data to be sent - preferably in the TCP SYN segment
146 Returns: connected socket number, or -1 with errno set
150 smtp_sock_connect(host_item * host, int host_af, int port, uschar * interface,
151 transport_instance * tb, int timeout, const blob * early_data)
153 smtp_transport_options_block * ob =
154 (smtp_transport_options_block *)tb->options_block;
155 const uschar * dscp = ob->dscp;
162 #ifndef DISABLE_EVENT
163 deliver_host_address = host->address;
164 deliver_host_port = port;
165 if (event_raise(tb->event_action, US"tcp:connect", NULL)) return -1;
168 if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1;
170 /* Set TCP_NODELAY; Exim does its own buffering. */
172 if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
173 HDEBUG(D_transport|D_acl|D_v)
174 debug_printf_indent("failed to set NODELAY: %s ", strerror(errno));
176 /* Set DSCP value, if we can. For now, if we fail to set the value, we don't
177 bomb out, just log it and continue in default traffic class. */
179 if (dscp && dscp_lookup(dscp, host_af, &dscp_level, &dscp_option, &dscp_value))
181 HDEBUG(D_transport|D_acl|D_v)
182 debug_printf_indent("DSCP \"%s\"=%x ", dscp, dscp_value);
183 if (setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value)) < 0)
184 HDEBUG(D_transport|D_acl|D_v)
185 debug_printf_indent("failed to set DSCP: %s ", strerror(errno));
186 /* If the kernel supports IPv4 and IPv6 on an IPv6 socket, we need to set the
187 option for both; ignore failures here */
188 if (host_af == AF_INET6 &&
189 dscp_lookup(dscp, AF_INET, &dscp_level, &dscp_option, &dscp_value))
190 (void) setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value));
193 /* Bind to a specific interface if requested. Caller must ensure the interface
194 is the same type (IPv4 or IPv6) as the outgoing address. */
196 if (interface && ip_bind(sock, host_af, interface, 0) < 0)
199 HDEBUG(D_transport|D_acl|D_v)
200 debug_printf_indent("unable to bind outgoing SMTP call to %s: %s", interface,
204 /* Connect to the remote host, and add keepalive to the socket before returning
205 it, if requested. If the build supports TFO, request it - and if the caller
206 requested some early-data then include that in the TFO request. */
210 const blob * fastopen = NULL;
213 if (verify_check_given_host(&ob->hosts_try_fastopen, host) == OK)
214 fastopen = early_data ? early_data : &tcp_fastopen_nodata;
217 if (ip_connect(sock, host_af, host->address, port, timeout, fastopen) < 0)
219 else if (early_data && !fastopen && early_data->data && early_data->len)
220 if (send(sock, early_data->data, early_data->len, 0) < 0)
224 /* Either bind() or connect() failed */
228 HDEBUG(D_transport|D_acl|D_v)
230 debug_printf_indent("failed: %s", CUstrerror(save_errno));
231 if (save_errno == ETIMEDOUT)
232 debug_printf(" (timeout=%s)", readconf_printtime(timeout));
240 /* Both bind() and connect() succeeded */
244 union sockaddr_46 interface_sock;
245 EXIM_SOCKLEN_T size = sizeof(interface_sock);
246 HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("connected\n");
247 if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0)
248 sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port);
251 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
252 "getsockname() failed: %s", strerror(errno));
256 if (ob->keepalive) ip_keepalive(sock, host->address, TRUE);
266 smtp_port_for_connect(host_item * host, int port)
268 if (host->port != PORT_NONE)
270 HDEBUG(D_transport|D_acl|D_v)
271 debug_printf_indent("Transport port=%d replaced by host-specific port=%d\n", port,
275 else host->port = port; /* Set the port actually used */
279 /*************************************************
280 * Connect to remote host *
281 *************************************************/
283 /* Create a socket, and connect it to a remote host. IPv6 addresses are
284 detected by checking for a colon in the address. AF_INET6 is defined even on
285 non-IPv6 systems, to enable the code to be less messy. However, on such systems
286 host->address will always be an IPv4 address.
289 host host item containing name and address and port
290 host_af AF_INET or AF_INET6
291 interface outgoing interface address or NULL
292 timeout timeout value or 0
295 Returns: connected socket number, or -1 with errno set
299 smtp_connect(host_item *host, int host_af, uschar *interface,
300 int timeout, transport_instance * tb)
302 int port = host->port;
304 smtp_transport_options_block * ob =
305 (smtp_transport_options_block *)tb->options_block;
308 callout_address = string_sprintf("[%s]:%d", host->address, port);
310 HDEBUG(D_transport|D_acl|D_v)
313 if (interface) s = string_sprintf(" from %s ", interface);
315 if (ob->socks_proxy) s = string_sprintf("%svia proxy ", s);
317 debug_printf_indent("Connecting to %s %s%s... ", host->name, callout_address, s);
320 /* Create and connect the socket */
324 return socks_sock_connect(host, host_af, port, interface, tb, timeout);
327 return smtp_sock_connect(host, host_af, port, interface, tb, timeout, NULL);
331 /*************************************************
332 * Flush outgoing command buffer *
333 *************************************************/
335 /* This function is called only from smtp_write_command() below. It flushes
336 the buffer of outgoing commands. There is more than one in the buffer only when
340 outblock the SMTP output block
341 mode further data expected, or plain
343 Returns: TRUE if OK, FALSE on error, with errno set
347 flush_buffer(smtp_outblock * outblock, int mode)
350 int n = outblock->ptr - outblock->buffer;
351 BOOL more = mode == SCMD_MORE;
353 HDEBUG(D_transport|D_acl) debug_printf_indent("cmd buf flush %d bytes%s\n", n,
354 more ? " (more expected)" : "");
357 if (tls_out.active == outblock->sock)
358 rc = tls_write(FALSE, outblock->buffer, n, more);
361 rc = send(outblock->sock, outblock->buffer, n,
371 HDEBUG(D_transport|D_acl) debug_printf_indent("send failed: %s\n", strerror(errno));
375 outblock->ptr = outblock->buffer;
376 outblock->cmd_count = 0;
382 /*************************************************
383 * Write SMTP command *
384 *************************************************/
386 /* The formatted command is left in big_buffer so that it can be reflected in
390 outblock contains buffer for pipelining, and socket
391 mode buffer, write-with-more-likely, write
392 format a format, starting with one of
393 of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT.
394 If NULL, flush pipeline buffer only.
395 ... data for the format
397 Returns: 0 if command added to pipelining buffer, with nothing transmitted
398 +n if n commands transmitted (may still have buffered the new one)
399 -1 on error, with errno set
403 smtp_write_command(smtp_outblock * outblock, int mode, const char *format, ...)
411 va_start(ap, format);
412 if (!string_vformat(big_buffer, big_buffer_size, CS format, ap))
413 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
416 count = Ustrlen(big_buffer);
418 if (count > outblock->buffersize)
419 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
422 if (count > outblock->buffersize - (outblock->ptr - outblock->buffer))
424 rc = outblock->cmd_count; /* flush resets */
425 if (!flush_buffer(outblock, SCMD_FLUSH)) return -1;
428 Ustrncpy(CS outblock->ptr, big_buffer, count);
429 outblock->ptr += count;
430 outblock->cmd_count++;
432 big_buffer[count] = 0; /* remove \r\n for error message */
434 /* We want to hide the actual data sent in AUTH transactions from reflections
435 and logs. While authenticating, a flag is set in the outblock to enable this.
436 The AUTH command itself gets any data flattened. Other lines are flattened
439 if (outblock->authenticating)
441 uschar *p = big_buffer;
442 if (Ustrncmp(big_buffer, "AUTH ", 5) == 0)
445 while (isspace(*p)) p++;
446 while (!isspace(*p)) p++;
447 while (isspace(*p)) p++;
449 while (*p != 0) *p++ = '*';
452 HDEBUG(D_transport|D_acl|D_v) debug_printf_indent(" SMTP>> %s\n", big_buffer);
455 if (mode != SCMD_BUFFER)
457 rc += outblock->cmd_count; /* flush resets */
458 if (!flush_buffer(outblock, mode)) return -1;
466 /*************************************************
467 * Read one line of SMTP response *
468 *************************************************/
470 /* This function reads one line of SMTP response from the server host. This may
471 not be a complete response - it could be just part of a multiline response. We
472 have to use a buffer for incoming packets, because when pipelining or using
473 LMTP, there may well be more than one response in a single packet. This
474 function is called only from the one that follows.
477 inblock the SMTP input block (contains holding buffer, socket, etc.)
478 buffer where to put the line
479 size space available for the line
480 timeout the timeout to use when reading a packet
482 Returns: length of a line that has been put in the buffer
483 -1 otherwise, with errno set
487 read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout)
490 uschar *ptr = inblock->ptr;
491 uschar *ptrend = inblock->ptrend;
492 int sock = inblock->sock;
494 /* Loop for reading multiple packets or reading another packet after emptying
495 a previously-read one. */
501 /* If there is data in the input buffer left over from last time, copy
502 characters from it until the end of a line, at which point we can return,
503 having removed any whitespace (which will include CR) at the end of the line.
504 The rules for SMTP say that lines end in CRLF, but there are have been cases
505 of hosts using just LF, and other MTAs are reported to handle this, so we
506 just look for LF. If we run out of characters before the end of a line,
507 carry on to read the next incoming packet. */
514 while (p > buffer && isspace(p[-1])) p--;
522 *p = 0; /* Leave malformed line for error message */
523 errno = ERRNO_SMTPFORMAT;
528 /* Need to read a new input packet. */
530 if((rc = ip_recv(sock, inblock->buffer, inblock->buffersize, timeout)) <= 0)
532 DEBUG(D_deliver|D_transport|D_acl)
533 debug_printf_indent(errno ? " SMTP(%s)<<\n" : " SMTP(closed)<<\n",
538 /* Another block of data has been successfully read. Set up the pointers
539 and let the loop continue. */
541 ptrend = inblock->ptrend = inblock->buffer + rc;
542 ptr = inblock->buffer;
543 DEBUG(D_transport|D_acl) debug_printf_indent("read response data: size=%d\n", rc);
546 /* Get here if there has been some kind of recv() error; errno is set, but we
547 ensure that the result buffer is empty before returning. */
557 /*************************************************
558 * Read SMTP response *
559 *************************************************/
561 /* This function reads an SMTP response with a timeout, and returns the
562 response in the given buffer, as a string. A multiline response will contain
563 newline characters between the lines. The function also analyzes the first
564 digit of the reply code and returns FALSE if it is not acceptable. FALSE is
565 also returned after a reading error. In this case buffer[0] will be zero, and
566 the error code will be in errno.
569 inblock the SMTP input block (contains holding buffer, socket, etc.)
570 buffer where to put the response
571 size the size of the buffer
572 okdigit the expected first digit of the response
573 timeout the timeout to use, in seconds
575 Returns: TRUE if a valid, non-error response was received; else FALSE
579 smtp_read_response(smtp_inblock *inblock, uschar *buffer, int size, int okdigit,
582 uschar *ptr = buffer;
585 errno = 0; /* Ensure errno starts out zero */
587 /* This is a loop to read and concatenate the lines that make up a multi-line
592 if ((count = read_response_line(inblock, ptr, size, timeout)) < 0)
595 HDEBUG(D_transport|D_acl|D_v)
596 debug_printf_indent(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr);
598 /* Check the format of the response: it must start with three digits; if
599 these are followed by a space or end of line, the response is complete. If
600 they are followed by '-' this is a multi-line response and we must look for
601 another line until the final line is reached. The only use made of multi-line
602 responses is to pass them back as error messages. We therefore just
603 concatenate them all within the buffer, which should be large enough to
604 accept any reasonable number of lines. */
610 (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0))
612 errno = ERRNO_SMTPFORMAT; /* format error */
616 /* If the line we have just read is a terminal line, line, we are done.
617 Otherwise more data has to be read. */
619 if (ptr[3] != '-') break;
621 /* Move the reading pointer upwards in the buffer and insert \n between the
622 components of a multiline response. Space is left for this by read_response_
630 /* Return a value that depends on the SMTP return code. On some systems a
631 non-zero value of errno has been seen at this point, so ensure it is zero,
632 because the caller of this function looks at errno when FALSE is returned, to
633 distinguish between an unexpected return code and other errors such as
634 timeouts, lost connections, etc. */
637 return buffer[0] == okdigit;
640 /* End of smtp_out.c */