2 * sink.c -- forwarding/delivery support for fetchmail
4 * The interface of this module (open_sink(), stuff_line(), close_sink(),
5 * release_sink()) seals off the delivery logic from the protocol machine,
6 * so the latter won't have to care whether it's shipping to an [SL]MTP
7 * listener daemon or an MDA pipe.
9 * Copyright 1998 by Eric S. Raymond
10 * For license terms, see the file COPYING in this directory.
12 * i18n by Arnaldo Carvalho de Melo <acme@conectiva.com.br> 7-Nov-1998
22 #endif /* HAVE_MEMORY_H */
23 #if defined(STDC_HEADERS)
26 #if defined(HAVE_UNISTD_H)
29 #if defined(HAVE_STDARG_H)
35 #include "fetchmail.h"
40 /* BSD portability hack...I know, this is an ugly place to put it */
41 #if !defined(SIGCHLD) && defined(SIGCLD)
42 #define SIGCHLD SIGCLD
45 static int smtp_open(struct query *ctl)
46 /* try to open a socket to the appropriate SMTP server for this query */
48 /* maybe it's time to close the socket in order to force delivery */
49 if (NUM_NONZERO(ctl->batchlimit) && (ctl->smtp_socket != -1) && batchcount++ == ctl->batchlimit)
51 close(ctl->smtp_socket);
52 ctl->smtp_socket = -1;
56 /* if no socket to any SMTP host is already set up, try to open one */
57 if (ctl->smtp_socket == -1)
60 * RFC 1123 requires that the domain name in HELO address is a
61 * "valid principal domain name" for the client host. If we're
62 * running in invisible mode, violate this with malice
63 * aforethought in order to make the Received headers and
66 * In fact this code relies on the RFC1123 requirement that the
67 * SMTP listener must accept messages even if verification of the
68 * HELO name fails (RFC1123 section 5.2.5, paragraph 2).
70 * How we compute the true mailhost name to pass to the
71 * listener doesn't affect behavior on RFC1123- violating
72 * listeners that check for name match; we're going to lose
73 * on those anyway because we can never give them a name
74 * that matches the local machine fetchmail is running on.
75 * What it will affect is the listener's logging.
78 const char *id_me = run.invisible ? ctl->server.truename : fetchmailhost;
84 * Run down the SMTP hunt list looking for a server that's up.
85 * Use both explicit hunt entries (value TRUE) and implicit
86 * (default) ones (value FALSE).
89 phase = LISTENER_WAIT;
91 set_timeout(ctl->server.timeout);
92 for (idp = ctl->smtphunt; idp; idp = idp->next)
94 char *cp, *parsed_host;
96 char *portnum = SMTP_PORT;
98 int portnum = SMTP_PORT;
101 xalloca(parsed_host, char *, strlen(idp->id) + 1);
103 ctl->smtphost = idp->id; /* remember last host tried. */
105 strcpy(parsed_host, idp->id);
106 if ((cp = strrchr(parsed_host, '/')))
116 if ((ctl->smtp_socket = SockOpen(parsed_host,portnum,NULL,
117 ctl->server.plugout)) == -1)
120 /* are we doing SMTP or LMTP? */
121 SMTP_setmode(ctl->listener);
123 /* first, probe for ESMTP */
124 if (SMTP_ok(ctl->smtp_socket) == SM_OK &&
125 SMTP_ehlo(ctl->smtp_socket, id_me,
126 &ctl->server.esmtp_options) == SM_OK)
130 * RFC 1869 warns that some listeners hang up on a failed EHLO,
131 * so it's safest not to assume the socket will still be good.
133 SockClose(ctl->smtp_socket);
134 ctl->smtp_socket = -1;
136 /* if opening for ESMTP failed, try SMTP */
137 if ((ctl->smtp_socket = SockOpen(parsed_host,portnum,NULL,
138 ctl->server.plugout)) == -1)
141 if (SMTP_ok(ctl->smtp_socket) == SM_OK &&
142 SMTP_helo(ctl->smtp_socket, id_me) == SM_OK)
145 SockClose(ctl->smtp_socket);
146 ctl->smtp_socket = -1;
153 * RFC 1123 requires that the domain name part of the
154 * RCPT TO address be "canonicalized", that is a FQDN
155 * or MX but not a CNAME. Some listeners (like exim)
156 * enforce this. Now that we have the actual hostname,
157 * compute what we should canonicalize with.
159 ctl->destaddr = ctl->smtpaddress ? ctl->smtpaddress : ( ctl->smtphost ? ctl->smtphost : "localhost");
161 if (outlevel >= O_DEBUG && ctl->smtp_socket != -1)
162 error(0, 0, _("forwarding to %s"), ctl->smtphost);
164 return(ctl->smtp_socket);
167 /* these are shared by open_sink and stuffline */
169 static RETSIGTYPE (*sigchld)(int);
171 int stuffline(struct query *ctl, char *buf)
172 /* ship a line to the given control block's output sink (SMTP server or MDA) */
177 /* The line may contain NUL characters. Find the last char to use
178 * -- the real line termination is the sequence "\n\0".
181 while ((last += strlen(last)) && (last[-1] != '\n'))
184 /* fix message lines that have only \n termination (for qmail) */
187 if (last - 1 == buf || last[-2] != '\r')
196 phase = FORWARDING_WAIT;
199 * SMTP byte-stuffing. We only do this if the protocol does *not*
200 * use .<CR><LF> as EOM. If it does, the server will already have
201 * decorated any . lines it sends back up.
204 if (ctl->server.base_protocol->delimited) /* server has already byte-stuffed */
209 /* writing to SMTP, leave the byte-stuffing in place */;
211 else /* if (!protocol->delimited) -- not byte-stuffed already */
214 SockWrite(ctl->smtp_socket, buf, 1); /* byte-stuff it */
216 /* leave it alone */;
219 /* we may need to strip carriage returns */
224 for (sp = tp = buf; sp < last; sp++)
232 if (ctl->mda || ctl->bsmtp)
233 n = fwrite(buf, 1, last - buf, sinkfp);
234 else if (ctl->smtp_socket != -1)
235 n = SockWrite(ctl->smtp_socket, buf, last - buf);
242 static void sanitize(char *s)
243 /* replace unsafe shellchars by an _ */
245 const static char *ok_chars = " 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
248 for (cp = s; *(cp += strspn(cp, ok_chars)); /* NO INCREMENT */)
252 static int send_bouncemail(struct msgblk *msg,
253 char *message, int nerrors, char *errors[])
254 /* bounce back an error report a la RFC 1892 */
256 char daemon_name[MSGBUFSIZE] = "FETCHMAIL-DAEMON@";
259 /* don't bounce in reply to undeliverable bounces */
260 if (!msg->return_path[0] || strcmp(msg->return_path, "<>") == 0)
263 SMTP_setmode(SMTP_MODE);
265 strcat(daemon_name, fetchmailhost);
267 /* we need only SMTP for this purpose */
268 if ((sock = SockOpen("localhost", SMTP_PORT, NULL, NULL)) == -1
269 || SMTP_ok(sock) != SM_OK
270 || SMTP_helo(sock, "localhost") != SM_OK
271 || SMTP_from(sock, daemon_name, (char *)NULL) != SM_OK
272 || SMTP_rcpt(sock, msg->return_path) != SM_OK
273 || SMTP_data(sock) != SM_OK)
276 error(0, 0, "SMTP: (bounce-message body)");
278 /* bouncemail headers */
279 SockPrintf(sock, "Return-Path: <>");
280 SockPrintf(sock, "From: FETCHMAIL-DAEMON@%s\r\n", fetchmailhost);
281 SockPrintf(sock, "To: %s\n", msg->return_path);
282 SockPrintf(sock, "MIME-Version: 1.0\r\n");
283 SockPrintf(sock, "Content-Type: multipart/report report-type=text/plain boundary=\"om-mani-padme-hum\"\r\n");
284 SockPrintf(sock, "Content-Transfer-Encoding: 7bit\r\n");
285 SockPrintf(sock, "\r\n");
287 /* RFC1892 part 1 -- human-readable message */
288 SockPrintf(sock, "-- om-mani-padme-hum\r\n");
289 SockPrintf(sock,"Content-Type: text/plain\r\n");
290 SockPrintf(sock, "\r\n");
291 SockWrite(sock, message, strlen(message));
293 /* RFC1892 part 2 -- machine-readable responses */
294 SockPrintf(sock, "-- om-mani-padme-hum\r\n");
295 SockPrintf(sock,"Content-Type: message/delivery-status\r\n");
296 SockPrintf(sock, "\r\n");
297 for (i = 0; i < nerrors; i++)
298 SockPrintf(sock, errors[i]);
300 /* RFC1892 part 3 -- headers of undelivered message */
301 SockPrintf(sock, "-- om-mani-padme-hum\r\n");
302 SockPrintf(sock, "Content-Type: text/rfc822-headers\r\n");
303 SockPrintf(sock, "\r\n");
304 SockWrite(sock, msg->headers, strlen(msg->headers));
305 SockPrintf(sock, "-- om-mani-padme-hum --\r\n");
307 if (SMTP_eom(sock) != SM_OK || SMTP_quit(sock))
315 int open_sink(struct query *ctl, struct msgblk *msg,
316 int *good_addresses, int *bad_addresses)
317 /* set up sinkfp to be an input sink we can ship a message to */
321 *bad_addresses = *good_addresses = 0;
323 if (ctl->bsmtp) /* dump to a BSMTP batch file */
325 if (strcmp(ctl->bsmtp, "-") == 0)
328 sinkfp = fopen(ctl->bsmtp, "a");
330 /* see the ap computation under the SMTP branch */
332 "MAIL FROM: %s", (msg->return_path[0]) ? msg->return_path : user);
334 if (ctl->pass8bits || (ctl->mimemsg & MSG_IS_8BIT))
335 fputs(" BODY=8BITMIME", sinkfp);
336 else if (ctl->mimemsg & MSG_IS_7BIT)
337 fputs(" BODY=7BIT", sinkfp);
339 fprintf(sinkfp, " SIZE=%ld\r\n", msg->reallen);
342 * RFC 1123 requires that the domain name part of the
343 * RCPT TO address be "canonicalized", that is a FQDN
344 * or MX but not a CNAME. Some listeners (like exim)
345 * enforce this. Now that we have the actual hostname,
346 * compute what we should canonicalize with.
348 ctl->destaddr = ctl->smtpaddress ? ctl->smtpaddress : "localhost";
351 for (idp = msg->recipients; idp; idp = idp->next)
352 if (idp->val.status.mark == XMIT_ACCEPT)
354 if (strchr(idp->id, '@'))
356 "RCPT TO: %s\r\n", idp->id);
359 "RCPT TO: %s@%s\r\n", idp->id, ctl->destaddr);
363 fputs("DATA\r\n", sinkfp);
367 error(0, -1, _("BSMTP file open or preamble write failed"));
371 else if (ctl->mda) /* we have a declared MDA */
373 int length = 0, fromlen = 0, nameslen = 0;
374 char *names = NULL, *before, *after, *from = NULL;
376 ctl->destaddr = "localhost";
378 for (idp = msg->recipients; idp; idp = idp->next)
379 if (idp->val.status.mark == XMIT_ACCEPT)
382 length = strlen(ctl->mda);
383 before = xstrdup(ctl->mda);
385 /* get user addresses for %T (or %s for backward compatibility) */
386 if (strstr(before, "%s") || strstr(before, "%T"))
389 * We go through this in order to be able to handle very
390 * long lists of users and (re)implement %s.
393 for (idp = msg->recipients; idp; idp = idp->next)
394 if ((idp->val.status.mark == XMIT_ACCEPT))
395 nameslen += (strlen(idp->id) + 1); /* string + ' ' */
396 if ((*good_addresses == 0))
397 nameslen = strlen(run.postmaster);
399 names = (char *)xmalloc(nameslen + 1); /* account for '\0' */
400 if (*good_addresses == 0)
401 strcpy(names, run.postmaster);
405 for (idp = msg->recipients; idp; idp = idp->next)
406 if (idp->val.status.mark == XMIT_ACCEPT)
408 strcat(names, idp->id);
411 names[--nameslen] = '\0'; /* chop trailing space */
414 /* sanitize names in order to contain only harmless shell chars */
418 /* get From address for %F */
419 if (strstr(before, "%F"))
421 from = xstrdup(msg->return_path);
423 /* sanitize from in order to contain *only* harmless shell chars */
426 fromlen = strlen(from);
429 /* do we have to build an mda string? */
434 /* find length of resulting mda string */
436 while ((sp = strstr(sp, "%s"))) {
437 length += nameslen - 2; /* subtract %s */
441 while ((sp = strstr(sp, "%T"))) {
442 length += nameslen - 2; /* subtract %T */
446 while ((sp = strstr(sp, "%F"))) {
447 length += fromlen - 2; /* subtract %F */
451 after = xmalloc(length + 1);
453 /* copy mda source string to after, while expanding %[sTF] */
454 for (dp = after, sp = before; (*dp = *sp); dp++, sp++) {
455 if (sp[0] != '%') continue;
457 /* need to expand? BTW, no here overflow, because in
458 ** the worst case (end of string) sp[1] == '\0' */
459 if (sp[1] == 's' || sp[1] == 'T') {
462 sp++; /* position sp over [sT] */
463 dp--; /* adjust dp */
464 } else if (sp[1] == 'F') {
467 sp++; /* position sp over F */
468 dp--; /* adjust dp */
487 if (outlevel >= O_DEBUG)
488 error(0, 0, _("about to deliver with: %s"), before);
492 * Arrange to run with user's permissions if we're root.
493 * This will initialize the ownership of any files the
494 * MDA creates properly. (The seteuid call is available
495 * under all BSDs and Linux)
498 #endif /* HAVE_SETEUID */
500 sinkfp = popen(before, "w");
505 /* this will fail quietly if we didn't start as root */
507 #endif /* HAVE_SETEUID */
511 error(0, 0, _("MDA open failed"));
515 sigchld = signal(SIGCHLD, SIG_DFL);
517 else /* forward to an SMTP or LMTP listener */
520 char options[MSGBUFSIZE], addr[128];
522 /* build a connection to the SMTP listener */
523 if ((smtp_open(ctl) == -1))
525 error(0, errno, _("%cMTP connect to %s failed"),
527 ctl->smtphost ? ctl->smtphost : "localhost");
532 * Compute ESMTP options.
535 if (ctl->server.esmtp_options & ESMTP_8BITMIME) {
536 if (ctl->pass8bits || (ctl->mimemsg & MSG_IS_8BIT))
537 strcpy(options, " BODY=8BITMIME");
538 else if (ctl->mimemsg & MSG_IS_7BIT)
539 strcpy(options, " BODY=7BIT");
542 if ((ctl->server.esmtp_options & ESMTP_SIZE) && msg->reallen > 0)
543 sprintf(options + strlen(options), " SIZE=%ld", msg->reallen);
546 * Try to get the SMTP listener to take the Return-Path
547 * address as MAIL FROM . If it won't, fall back on the
548 * calling-user ID. This won't affect replies, which use the
549 * header From address anyway.
551 * RFC 1123 requires that the domain name part of the
552 * MAIL FROM address be "canonicalized", that is a
553 * FQDN or MX but not a CNAME. We'll assume the From
554 * header is already in this form here (it certainly
555 * is if rewrite is on). RFC 1123 is silent on whether
556 * a nonexistent hostname part is considered canonical.
558 * This is a potential problem if the MTAs further upstream
559 * didn't pass canonicalized From/Return-Path lines, *and* the
560 * local SMTP listener insists on them.
562 ap = (msg->return_path[0]) ? msg->return_path : user;
563 if (SMTP_from(ctl->smtp_socket, ap, options) != SM_OK)
565 int smtperr = atoi(smtp_response);
568 responses[0] = smtp_response;
570 if (str_find(&ctl->antispam, smtperr))
573 * SMTP listener explicitly refuses to deliver mail
574 * coming from this address, probably due to an
575 * anti-spam domain exclusion. Respect this. Don't
576 * try to ship the message, and don't prevent it from
577 * being deleted. Typical values:
579 * 501 = exim's old antispam response
580 * 550 = exim's new antispam response (temporary)
581 * 553 = sendmail 8.8.7's generic REJECT
582 * 571 = sendmail's "unsolicited email refused"
585 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
587 _("We do not accept mail from you.)\r\n"),
593 * Suppress error message only if the response specifically
594 * meant `excluded for policy reasons'. We *should* see
595 * an error when the return code is less specific.
598 error(0, -1, _("%cMTP error: %s"),
604 case 452: /* insufficient system storage */
606 * Temporary out-of-queue-space condition on the
607 * ESMTP server. Don't try to ship the message,
608 * and suppress deletion so it can be retried on
609 * a future retrieval cycle.
611 * Bouncemail *might* be appropriate here as a delay
612 * notification. But it's not really necessary because
613 * this is not an actual failure, we're very likely to be
614 * able to recover on the next cycle.
616 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
617 return(PS_TRANSIENT);
619 case 552: /* message exceeds fixed maximum message size */
621 * Permanent no-go condition on the
622 * ESMTP server. Don't try to ship the message,
623 * and allow it to be deleted.
625 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
627 _("This message was too large.\r\n"),
631 case 553: /* invalid sending domain */
633 * These latter days 553 usually means a spammer is trying to
636 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
638 _("Invalid address.\r\n"),
642 default: /* retry with postmaster's address */
643 if (SMTP_from(ctl->smtp_socket,run.postmaster,options)!=SM_OK)
645 error(0, -1, _("%cMTP error: %s"),
648 return(PS_SMTP); /* should never happen */
654 * Now list the recipient addressees
656 for (idp = msg->recipients; idp; idp = idp->next)
657 if (idp->val.status.mark == XMIT_ACCEPT)
659 if (strchr(idp->id, '@'))
660 strcpy(addr, idp->id);
663 snprintf(addr, sizeof(addr)-1, "%s@%s", idp->id, ctl->destaddr);
665 sprintf(addr, "%s@%s", idp->id, ctl->destaddr);
666 #endif /* HAVE_SNPRINTF */
668 if (SMTP_rcpt(ctl->smtp_socket, addr) == SM_OK)
673 idp->val.status.mark = XMIT_ANTISPAM;
675 _("%cMTP listener doesn't like recipient address `%s'"),
676 ctl->listener, addr);
679 if (!(*good_addresses))
682 snprintf(addr, sizeof(addr)-1, "%s@%s", run.postmaster, ctl->destaddr);
684 sprintf(addr, "%s@%s", run.postmaster, ctl->destaddr);
685 #endif /* HAVE_SNPRINTF */
687 if (SMTP_rcpt(ctl->smtp_socket, addr) != SM_OK)
689 error(0, 0, _("can't even send to %s!"), run.postmaster);
690 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
695 /* tell it we're ready to send data */
696 SMTP_data(ctl->smtp_socket);
700 * We need to stash this away in order to know how many
701 * response lines to expect after the LMTP end-of-message.
703 msg->lmtp_responses = *good_addresses;
708 void release_sink(struct query *ctl)
709 /* release the per-message output sink, whether it's a pipe or SMTP socket */
718 sinkfp = (FILE *)NULL;
720 signal(SIGCHLD, sigchld);
724 int close_sink(struct query *ctl, struct msgblk *msg, flag forward)
725 /* perform end-of-message actions on the current output sink */
731 /* close the delivery pipe, we'll reopen before next message */
735 sinkfp = (FILE *)NULL;
739 signal(SIGCHLD, sigchld);
742 error(0, -1, _("MDA exited abnormally or returned nonzero status"));
748 /* implicit disk-full check here... */
749 fputs("..\r\n", sinkfp);
750 if (strcmp(ctl->bsmtp, "-"))
754 error(0, -1, _("Message termination or close of BSMTP file failed"));
760 /* write message terminator */
761 if (SMTP_eom(ctl->smtp_socket) != SM_OK)
763 error(0, -1, _("SMTP listener refused delivery"));
768 * If this is an SMTP connection, SMTP_eom() ate the response.
769 * But could be this is an LMTP connection, in which case we have to
770 * interpret either (a) a single 503 response meaning there
771 * were no successful RCPT TOs, or (b) a variable number of
772 * responses, one for each successful RCPT TO. We need to send
773 * bouncemail on each failed response and then return TRUE anyway,
774 * otherwise the message will get left in the queue and resent
775 * to people who got it the first time.
777 if (ctl->listener == LMTP_MODE)
778 if (msg->lmtp_responses == 0)
780 SMTP_ok(ctl->smtp_socket);
783 * According to RFC2033, 503 is the only legal response
784 * if no RCPT TO commands succeeded. No error recovery
785 * is really possible here, as we have no idea what
786 * insane thing the listener might be doing if it doesn't
789 if (atoi(smtp_response) == 503)
790 error(0, -1, _("LMTP delivery error on EOM"));
793 _("Unexpected non-503 response to LMTP EOM: %s"),
797 * It's not completely clear what to do here. We choose to
798 * interpret delivery failure here as a transient error,
799 * the same way SMTP delivery failure is handled. If we're
800 * wrong, an undead message will get stuck in the queue.
809 /* eat the RFC2033-required responses, saving errors */
810 xalloca(responses, char **, sizeof(char *) * msg->lmtp_responses);
811 for (errors = i = 0; i < msg->lmtp_responses; i++)
813 if (SMTP_ok(ctl->smtp_socket) == SM_OK)
814 responses[i] = (char *)NULL;
817 xalloca(responses[errors],
819 strlen(smtp_response)+1);
820 strcpy(responses[errors], smtp_response);
826 return(TRUE); /* all deliveries succeeded */
830 * One or more deliveries failed.
831 * If we can bounce a failures list back to the sender,
832 * return TRUE, deleting the message from the server so
833 * it won't be re-forwarded on subsequent poll
836 return(send_bouncemail(msg,
837 "LSMTP partial delivery failure.\r\n",
846 int open_warning_by_mail(struct query *ctl, struct msgblk *msg)
847 /* set up output sink for a mailed warning to calling user */
852 * Dispatching warning email is a little complicated. The problem is
853 * that we have to deal with three distinct cases:
855 * 1. Single-drop running from user account. Warning mail should
856 * go to the local name for which we're collecting (coincides
857 * with calling user).
859 * 2. Single-drop running from root or other privileged ID, with rc
860 * file generated on the fly (Ken Estes's weird setup...) Mail
861 * should go to the local name for which we're collecting (does not
862 * coincide with calling user).
864 * 3. Multidrop. Mail must go to postmaster. We leave the recipients
865 * member null so this message will fall through to run.postmaster.
867 * The zero in the reallen element means we won't pass a SIZE
868 * option to ESMTP; the message length would be more trouble than
869 * it's worth to compute.
871 struct msgblk reply = {NULL, NULL, "FETCHMAIL-DAEMON", 0};
873 if (!MULTIDROP(ctl)) /* send to calling user */
877 save_str(&reply.recipients, ctl->localnames->id, XMIT_ACCEPT);
878 status = open_sink(ctl, &reply, &good, &bad);
879 free_str_list(&reply.recipients);
882 else /* send to postmaster */
883 return(open_sink(ctl, &reply, &good, &bad));
886 #if defined(HAVE_STDARG_H)
887 void stuff_warning(struct query *ctl, const char *fmt, ... )
889 void stuff_warning(struct query *ctl, fmt, va_alist)
891 const char *fmt; /* printf-style format */
894 /* format and ship a warning message line by mail */
896 char buf[POPBUFSIZE];
900 * stuffline() requires its input to be writeable (for CR stripping),
901 * so we needed to copy the message to a writeable buffer anyway in
902 * case it was a string constant. We make a virtue of that necessity
903 * here by supporting stdargs/varargs.
905 #if defined(HAVE_STDARG_H)
910 #ifdef HAVE_VSNPRINTF
911 vsnprintf(buf, sizeof(buf), fmt, ap);
913 vsprintf(buf, fmt, ap);
922 void close_warning_by_mail(struct query *ctl, struct msgblk *msg)
923 /* sign and send mailed warnings */
925 stuff_warning(ctl, "--\r\n\t\t\t\tThe Fetchmail Daemon\r\n");
926 close_sink(ctl, msg, TRUE);
929 /* sink.c ends here */