1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
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 changed if not NULL, set TRUE if expansion actually changed istring
30 interface point this to the interface
31 msg to add to any error message
33 Returns: TRUE on success, FALSE on failure, with error message
34 set in addr and transport_return set to PANIC
38 smtp_get_interface(uschar *istring, int host_af, address_item *addr,
39 BOOL *changed, uschar **interface, uschar *msg)
41 const uschar * expint;
45 if (istring == NULL) return TRUE;
47 expint = expand_string(istring);
50 if (expand_string_forcedfail) return TRUE;
51 addr->transport_return = PANIC;
52 addr->message = string_sprintf("failed to expand \"interface\" "
53 "option for %s: %s", msg, expand_string_message);
57 if (changed != NULL) *changed = expint != istring;
59 while (isspace(*expint)) expint++;
60 if (*expint == 0) return TRUE;
62 while ((iface = string_nextinlist(&expint, &sep, big_buffer,
63 big_buffer_size)) != NULL)
65 if (string_is_ip_address(iface, NULL) == 0)
67 addr->transport_return = PANIC;
68 addr->message = string_sprintf("\"%s\" is not a valid IP "
69 "address for the \"interface\" option for %s",
74 if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af)
78 if (iface != NULL) *interface = string_copy(iface);
84 /*************************************************
85 * Find an outgoing port *
86 *************************************************/
88 /* This function is called from the smtp transport and also from the callout
89 code in verify.c. Its job is to find a port number. Note that getservbyname()
90 produces the number in network byte order.
93 rstring raw (unexpanded) string representation of the port
94 addr the mail address being handled (for setting errors)
95 port stick the port in here
96 msg for adding to error message
98 Returns: TRUE on success, FALSE on failure, with error message set
99 in addr, and transport_return set to PANIC
103 smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg)
105 uschar *pstring = expand_string(rstring);
109 addr->transport_return = PANIC;
110 addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) "
111 "for %s: %s", rstring, msg, expand_string_message);
115 if (isdigit(*pstring))
118 *port = Ustrtol(pstring, &end, 0);
119 if (end != pstring + Ustrlen(pstring))
121 addr->transport_return = PANIC;
122 addr->message = string_sprintf("invalid port number for %s: %s", msg,
130 struct servent *smtp_service = getservbyname(CS pstring, "tcp");
131 if (smtp_service == NULL)
133 addr->transport_return = PANIC;
134 addr->message = string_sprintf("TCP port \"%s\" is not defined for %s",
138 *port = ntohs(smtp_service->s_port);
148 smtp_sock_connect(host_item * host, int host_af, int port, uschar * interface,
149 transport_instance * tb, int timeout)
151 smtp_transport_options_block * ob =
152 (smtp_transport_options_block *)tb->options_block;
153 const uschar * dscp = ob->dscp;
161 #ifdef EXPERIMENTAL_EVENT
162 deliver_host_address = host->address;
163 deliver_host_port = port;
164 if (event_raise(tb->event_action, US"tcp:connect", NULL)) return -1;
167 if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1;
169 /* Set TCP_NODELAY; Exim does its own buffering. */
171 setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (uschar *)(&on), sizeof(on));
173 /* Set DSCP value, if we can. For now, if we fail to set the value, we don't
174 bomb out, just log it and continue in default traffic class. */
176 if (dscp && dscp_lookup(dscp, host_af, &dscp_level, &dscp_option, &dscp_value))
178 HDEBUG(D_transport|D_acl|D_v)
179 debug_printf("DSCP \"%s\"=%x ", dscp, dscp_value);
180 if (setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value)) < 0)
181 HDEBUG(D_transport|D_acl|D_v)
182 debug_printf("failed to set DSCP: %s ", strerror(errno));
183 /* If the kernel supports IPv4 and IPv6 on an IPv6 socket, we need to set the
184 option for both; ignore failures here */
185 if (host_af == AF_INET6 &&
186 dscp_lookup(dscp, AF_INET, &dscp_level, &dscp_option, &dscp_value))
187 (void) setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value));
190 /* Bind to a specific interface if requested. Caller must ensure the interface
191 is the same type (IPv4 or IPv6) as the outgoing address. */
193 if (interface && ip_bind(sock, host_af, interface, 0) < 0)
196 HDEBUG(D_transport|D_acl|D_v)
197 debug_printf("unable to bind outgoing SMTP call to %s: %s", interface,
201 /* Connect to the remote host, and add keepalive to the socket before returning
204 else if (ip_connect(sock, host_af, host->address, port, timeout) < 0)
207 /* Either bind() or connect() failed */
211 HDEBUG(D_transport|D_acl|D_v)
213 debug_printf("failed: %s", CUstrerror(save_errno));
214 if (save_errno == ETIMEDOUT)
215 debug_printf(" (timeout=%s)", readconf_printtime(timeout));
223 /* Both bind() and connect() succeeded */
227 union sockaddr_46 interface_sock;
228 EXIM_SOCKLEN_T size = sizeof(interface_sock);
229 HDEBUG(D_transport|D_acl|D_v) debug_printf("connected\n");
230 if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0)
231 sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port);
234 log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
235 "getsockname() failed: %s", strerror(errno));
239 if (ob->keepalive) ip_keepalive(sock, host->address, TRUE);
244 /*************************************************
245 * Connect to remote host *
246 *************************************************/
248 /* Create a socket, and connect it to a remote host. IPv6 addresses are
249 detected by checking for a colon in the address. AF_INET6 is defined even on
250 non-IPv6 systems, to enable the code to be less messy. However, on such systems
251 host->address will always be an IPv4 address.
253 The port field in the host item is used if it is set (usually router from SRV
254 records or elsewhere). In other cases, the default passed as an argument is
255 used, and the host item is updated with its value.
258 host host item containing name and address (and sometimes port)
259 host_af AF_INET or AF_INET6
260 port default remote port to connect to, in host byte order, for those
261 hosts whose port setting is PORT_NONE
262 interface outgoing interface address or NULL
263 timeout timeout value or 0
266 Returns: connected socket number, or -1 with errno set
270 smtp_connect(host_item *host, int host_af, int port, uschar *interface,
271 int timeout, transport_instance * tb)
273 smtp_transport_options_block * ob =
274 (smtp_transport_options_block *)tb->options_block;
276 if (host->port != PORT_NONE)
278 HDEBUG(D_transport|D_acl|D_v)
279 debug_printf("Transport port=%d replaced by host-specific port=%d\n", port,
283 else host->port = port; /* Set the port actually used */
285 HDEBUG(D_transport|D_acl|D_v)
288 if (interface) s = string_sprintf(" from %s ", interface);
289 #ifdef EXPERIMENTAL_SOCKS
290 if (ob->socks_proxy) s = string_sprintf("%svia proxy ", s);
292 debug_printf("Connecting to %s [%s]:%d%s... ",
293 host->name, host->address, port, s);
296 /* Create and connect the socket */
298 #ifdef EXPERIMENTAL_SOCKS
300 return socks_sock_connect(host, host_af, port, interface, tb, timeout);
303 return smtp_sock_connect(host, host_af, port, interface, tb, timeout);
307 /*************************************************
308 * Flush outgoing command buffer *
309 *************************************************/
311 /* This function is called only from smtp_write_command() below. It flushes
312 the buffer of outgoing commands. There is more than one in the buffer only when
316 outblock the SMTP output block
318 Returns: TRUE if OK, FALSE on error, with errno set
322 flush_buffer(smtp_outblock *outblock)
327 if (tls_out.active == outblock->sock)
328 rc = tls_write(FALSE, outblock->buffer, outblock->ptr - outblock->buffer);
332 rc = send(outblock->sock, outblock->buffer, outblock->ptr - outblock->buffer, 0);
335 HDEBUG(D_transport|D_acl) debug_printf("send failed: %s\n", strerror(errno));
339 outblock->ptr = outblock->buffer;
340 outblock->cmd_count = 0;
346 /*************************************************
347 * Write SMTP command *
348 *************************************************/
350 /* The formatted command is left in big_buffer so that it can be reflected in
354 outblock contains buffer for pipelining, and socket
355 noflush if TRUE, save the command in the output buffer, for pipelining
356 format a format, starting with one of
357 of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT.
358 ... data for the format
360 Returns: 0 if command added to pipelining buffer, with nothing transmitted
361 +n if n commands transmitted (may still have buffered the new one)
362 -1 on error, with errno set
366 smtp_write_command(smtp_outblock *outblock, BOOL noflush, const char *format, ...)
372 va_start(ap, format);
373 if (!string_vformat(big_buffer, big_buffer_size, CS format, ap))
374 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
377 count = Ustrlen(big_buffer);
379 if (count > outblock->buffersize)
380 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
383 if (count > outblock->buffersize - (outblock->ptr - outblock->buffer))
385 rc = outblock->cmd_count; /* flush resets */
386 if (!flush_buffer(outblock)) return -1;
389 Ustrncpy(CS outblock->ptr, big_buffer, count);
390 outblock->ptr += count;
391 outblock->cmd_count++;
393 big_buffer[count] = 0; /* remove \r\n for error message */
395 /* We want to hide the actual data sent in AUTH transactions from reflections
396 and logs. While authenticating, a flag is set in the outblock to enable this.
397 The AUTH command itself gets any data flattened. Other lines are flattened
400 if (outblock->authenticating)
402 uschar *p = big_buffer;
403 if (Ustrncmp(big_buffer, "AUTH ", 5) == 0)
406 while (isspace(*p)) p++;
407 while (!isspace(*p)) p++;
408 while (isspace(*p)) p++;
410 while (*p != 0) *p++ = '*';
413 HDEBUG(D_transport|D_acl|D_v) debug_printf(" SMTP>> %s\n", big_buffer);
417 rc += outblock->cmd_count; /* flush resets */
418 if (!flush_buffer(outblock)) return -1;
426 /*************************************************
427 * Read one line of SMTP response *
428 *************************************************/
430 /* This function reads one line of SMTP response from the server host. This may
431 not be a complete response - it could be just part of a multiline response. We
432 have to use a buffer for incoming packets, because when pipelining or using
433 LMTP, there may well be more than one response in a single packet. This
434 function is called only from the one that follows.
437 inblock the SMTP input block (contains holding buffer, socket, etc.)
438 buffer where to put the line
439 size space available for the line
440 timeout the timeout to use when reading a packet
442 Returns: length of a line that has been put in the buffer
443 -1 otherwise, with errno set
447 read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout)
450 uschar *ptr = inblock->ptr;
451 uschar *ptrend = inblock->ptrend;
452 int sock = inblock->sock;
454 /* Loop for reading multiple packets or reading another packet after emptying
455 a previously-read one. */
461 /* If there is data in the input buffer left over from last time, copy
462 characters from it until the end of a line, at which point we can return,
463 having removed any whitespace (which will include CR) at the end of the line.
464 The rules for SMTP say that lines end in CRLF, but there are have been cases
465 of hosts using just LF, and other MTAs are reported to handle this, so we
466 just look for LF. If we run out of characters before the end of a line,
467 carry on to read the next incoming packet. */
474 while (p > buffer && isspace(p[-1])) p--;
482 *p = 0; /* Leave malformed line for error message */
483 errno = ERRNO_SMTPFORMAT;
488 /* Need to read a new input packet. */
490 rc = ip_recv(sock, inblock->buffer, inblock->buffersize, timeout);
493 /* Another block of data has been successfully read. Set up the pointers
494 and let the loop continue. */
496 ptrend = inblock->ptrend = inblock->buffer + rc;
497 ptr = inblock->buffer;
498 DEBUG(D_transport|D_acl) debug_printf("read response data: size=%d\n", rc);
501 /* Get here if there has been some kind of recv() error; errno is set, but we
502 ensure that the result buffer is empty before returning. */
512 /*************************************************
513 * Read SMTP response *
514 *************************************************/
516 /* This function reads an SMTP response with a timeout, and returns the
517 response in the given buffer, as a string. A multiline response will contain
518 newline characters between the lines. The function also analyzes the first
519 digit of the reply code and returns FALSE if it is not acceptable. FALSE is
520 also returned after a reading error. In this case buffer[0] will be zero, and
521 the error code will be in errno.
524 inblock the SMTP input block (contains holding buffer, socket, etc.)
525 buffer where to put the response
526 size the size of the buffer
527 okdigit the expected first digit of the response
528 timeout the timeout to use
530 Returns: TRUE if a valid, non-error response was received; else FALSE
534 smtp_read_response(smtp_inblock *inblock, uschar *buffer, int size, int okdigit,
537 uschar *ptr = buffer;
540 errno = 0; /* Ensure errno starts out zero */
542 /* This is a loop to read and concatentate the lines that make up a multi-line
547 if ((count = read_response_line(inblock, ptr, size, timeout)) < 0)
550 HDEBUG(D_transport|D_acl|D_v)
551 debug_printf(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr);
553 /* Check the format of the response: it must start with three digits; if
554 these are followed by a space or end of line, the response is complete. If
555 they are followed by '-' this is a multi-line response and we must look for
556 another line until the final line is reached. The only use made of multi-line
557 responses is to pass them back as error messages. We therefore just
558 concatenate them all within the buffer, which should be large enough to
559 accept any reasonable number of lines. */
565 (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0))
567 errno = ERRNO_SMTPFORMAT; /* format error */
571 /* If the line we have just read is a terminal line, line, we are done.
572 Otherwise more data has to be read. */
574 if (ptr[3] != '-') break;
576 /* Move the reading pointer upwards in the buffer and insert \n between the
577 components of a multiline response. Space is left for this by read_response_
585 /* Return a value that depends on the SMTP return code. On some systems a
586 non-zero value of errno has been seen at this point, so ensure it is zero,
587 because the caller of this function looks at errno when FALSE is returned, to
588 distinguish between an unexpected return code and other errors such as
589 timeouts, lost connections, etc. */
592 return buffer[0] == okdigit;
595 /* End of smtp_out.c */