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[18 + HOSTLEN] = "FETCHMAIL-DAEMON@";
257 char boundary[BUFSIZ];
260 /* don't bounce in reply to undeliverable bounces */
261 if (!msg->return_path[0] || strcmp(msg->return_path, "<>") == 0)
264 SMTP_setmode(SMTP_MODE);
266 strcat(daemon_name, fetchmailhost);
268 /* we need only SMTP for this purpose */
269 if ((sock = SockOpen("localhost", SMTP_PORT, NULL, NULL)) == -1
270 || SMTP_ok(sock) != SM_OK
271 || SMTP_helo(sock, "localhost") != SM_OK
272 || SMTP_from(sock, daemon_name, (char *)NULL) != SM_OK
273 || SMTP_rcpt(sock, msg->return_path) != SM_OK
274 || SMTP_data(sock) != SM_OK)
278 "om-mani-padme-hum-%d-%d-%ld",
279 getpid(), getppid(), time((time_t *)NULL));
281 if (outlevel >= O_VERBOSE)
282 error(0, 0, "SMTP: (bounce-message body)");
284 /* bouncemail headers */
285 SockPrintf(sock, "Return-Path: <>");
286 SockPrintf(sock, "From: FETCHMAIL-DAEMON@%s\r\n", fetchmailhost);
287 SockPrintf(sock, "To: %s\n", msg->return_path);
288 SockPrintf(sock, "MIME-Version: 1.0\r\n");
289 SockPrintf(sock, "Content-Type: multipart/report; report-type=delivery-status boundary=\"%s\"\r\n", boundary);
290 SockPrintf(sock, "\r\n");
291 SockPrintf(sock, "Content-Transfer-Encoding: 7bit\r\n");
292 SockPrintf(sock, "\r\n");
294 /* RFC1892 part 1 -- human-readable message */
295 SockPrintf(sock, "--%s\r\n", boundary);
296 SockPrintf(sock,"Content-Type: text/plain\r\n");
297 SockPrintf(sock, "\r\n");
298 SockWrite(sock, message, strlen(message));
299 SockPrintf(sock, "\r\n");
303 /* RFC1892 part 2 -- machine-readable responses */
304 SockPrintf(sock, "--%s\r\n", boundary);
305 SockPrintf(sock,"Content-Type: message/delivery-status\r\n");
306 SockPrintf(sock, "\r\n");
307 for (i = 0; i < nerrors; i++)
308 SockPrintf(sock, errors[i]);
309 SockPrintf(sock, "\r\n");
312 /* RFC1892 part 3 -- headers of undelivered message */
313 SockPrintf(sock, "--%s\r\n", boundary);
314 SockPrintf(sock, "Content-Type: text/rfc822-headers\r\n");
315 SockPrintf(sock, "\r\n");
316 SockWrite(sock, msg->headers, strlen(msg->headers));
317 SockPrintf(sock, "\r\n");
318 SockPrintf(sock, "--%s--\r\n", boundary);
320 if (SMTP_eom(sock) != SM_OK || SMTP_quit(sock))
328 int open_sink(struct query *ctl, struct msgblk *msg,
329 int *good_addresses, int *bad_addresses)
330 /* set up sinkfp to be an input sink we can ship a message to */
334 *bad_addresses = *good_addresses = 0;
336 if (ctl->bsmtp) /* dump to a BSMTP batch file */
338 if (strcmp(ctl->bsmtp, "-") == 0)
341 sinkfp = fopen(ctl->bsmtp, "a");
343 /* see the ap computation under the SMTP branch */
345 "MAIL FROM: %s", (msg->return_path[0]) ? msg->return_path : user);
347 if (ctl->pass8bits || (ctl->mimemsg & MSG_IS_8BIT))
348 fputs(" BODY=8BITMIME", sinkfp);
349 else if (ctl->mimemsg & MSG_IS_7BIT)
350 fputs(" BODY=7BIT", sinkfp);
352 fprintf(sinkfp, " SIZE=%ld\r\n", msg->reallen);
355 * RFC 1123 requires that the domain name part of the
356 * RCPT TO address be "canonicalized", that is a FQDN
357 * or MX but not a CNAME. Some listeners (like exim)
358 * enforce this. Now that we have the actual hostname,
359 * compute what we should canonicalize with.
361 ctl->destaddr = ctl->smtpaddress ? ctl->smtpaddress : "localhost";
364 for (idp = msg->recipients; idp; idp = idp->next)
365 if (idp->val.status.mark == XMIT_ACCEPT)
367 if (strchr(idp->id, '@'))
369 "RCPT TO: %s\r\n", idp->id);
372 "RCPT TO: %s@%s\r\n", idp->id, ctl->destaddr);
376 fputs("DATA\r\n", sinkfp);
380 error(0, -1, _("BSMTP file open or preamble write failed"));
384 else if (ctl->mda) /* we have a declared MDA */
386 int length = 0, fromlen = 0, nameslen = 0;
387 char *names = NULL, *before, *after, *from = NULL;
389 ctl->destaddr = "localhost";
391 for (idp = msg->recipients; idp; idp = idp->next)
392 if (idp->val.status.mark == XMIT_ACCEPT)
395 length = strlen(ctl->mda);
396 before = xstrdup(ctl->mda);
398 /* get user addresses for %T (or %s for backward compatibility) */
399 if (strstr(before, "%s") || strstr(before, "%T"))
402 * We go through this in order to be able to handle very
403 * long lists of users and (re)implement %s.
406 for (idp = msg->recipients; idp; idp = idp->next)
407 if ((idp->val.status.mark == XMIT_ACCEPT))
408 nameslen += (strlen(idp->id) + 1); /* string + ' ' */
409 if ((*good_addresses == 0))
410 nameslen = strlen(run.postmaster);
412 names = (char *)xmalloc(nameslen + 1); /* account for '\0' */
413 if (*good_addresses == 0)
414 strcpy(names, run.postmaster);
418 for (idp = msg->recipients; idp; idp = idp->next)
419 if (idp->val.status.mark == XMIT_ACCEPT)
421 strcat(names, idp->id);
424 names[--nameslen] = '\0'; /* chop trailing space */
427 /* sanitize names in order to contain only harmless shell chars */
431 /* get From address for %F */
432 if (strstr(before, "%F"))
434 from = xstrdup(msg->return_path);
436 /* sanitize from in order to contain *only* harmless shell chars */
439 fromlen = strlen(from);
442 /* do we have to build an mda string? */
447 /* find length of resulting mda string */
449 while ((sp = strstr(sp, "%s"))) {
450 length += nameslen - 2; /* subtract %s */
454 while ((sp = strstr(sp, "%T"))) {
455 length += nameslen - 2; /* subtract %T */
459 while ((sp = strstr(sp, "%F"))) {
460 length += fromlen - 2; /* subtract %F */
464 after = xmalloc(length + 1);
466 /* copy mda source string to after, while expanding %[sTF] */
467 for (dp = after, sp = before; (*dp = *sp); dp++, sp++) {
468 if (sp[0] != '%') continue;
470 /* need to expand? BTW, no here overflow, because in
471 ** the worst case (end of string) sp[1] == '\0' */
472 if (sp[1] == 's' || sp[1] == 'T') {
475 sp++; /* position sp over [sT] */
476 dp--; /* adjust dp */
477 } else if (sp[1] == 'F') {
480 sp++; /* position sp over F */
481 dp--; /* adjust dp */
500 if (outlevel >= O_DEBUG)
501 error(0, 0, _("about to deliver with: %s"), before);
505 * Arrange to run with user's permissions if we're root.
506 * This will initialize the ownership of any files the
507 * MDA creates properly. (The seteuid call is available
508 * under all BSDs and Linux)
511 #endif /* HAVE_SETEUID */
513 sinkfp = popen(before, "w");
518 /* this will fail quietly if we didn't start as root */
520 #endif /* HAVE_SETEUID */
524 error(0, 0, _("MDA open failed"));
528 sigchld = signal(SIGCHLD, SIG_DFL);
530 else /* forward to an SMTP or LMTP listener */
533 char options[MSGBUFSIZE], addr[128];
535 /* build a connection to the SMTP listener */
536 if ((smtp_open(ctl) == -1))
538 error(0, errno, _("%cMTP connect to %s failed"),
540 ctl->smtphost ? ctl->smtphost : "localhost");
545 * Compute ESMTP options.
548 if (ctl->server.esmtp_options & ESMTP_8BITMIME) {
549 if (ctl->pass8bits || (ctl->mimemsg & MSG_IS_8BIT))
550 strcpy(options, " BODY=8BITMIME");
551 else if (ctl->mimemsg & MSG_IS_7BIT)
552 strcpy(options, " BODY=7BIT");
555 if ((ctl->server.esmtp_options & ESMTP_SIZE) && msg->reallen > 0)
556 sprintf(options + strlen(options), " SIZE=%ld", msg->reallen);
559 * Try to get the SMTP listener to take the Return-Path
560 * address as MAIL FROM . If it won't, fall back on the
561 * calling-user ID. This won't affect replies, which use the
562 * header From address anyway.
564 * RFC 1123 requires that the domain name part of the
565 * MAIL FROM address be "canonicalized", that is a
566 * FQDN or MX but not a CNAME. We'll assume the From
567 * header is already in this form here (it certainly
568 * is if rewrite is on). RFC 1123 is silent on whether
569 * a nonexistent hostname part is considered canonical.
571 * This is a potential problem if the MTAs further upstream
572 * didn't pass canonicalized From/Return-Path lines, *and* the
573 * local SMTP listener insists on them.
575 * Note: send_bouncemail message strings are not made subject
576 * to gettext translation because (a) they're going to be
577 * embedded in a text/plain 7bit part, and (b) they're
578 * going to be associated with listener error-response
579 * messages, which are probably in English (none of the
580 * MTAs I know about are internationalized).
582 ap = (msg->return_path[0]) ? msg->return_path : user;
583 if (SMTP_from(ctl->smtp_socket, ap, options) != SM_OK)
585 int smtperr = atoi(smtp_response);
588 responses[0] = smtp_response;
590 /* required by RFC1870; sets us up to be able to send bouncemail */
591 SMTP_rset(ctl->smtp_socket);
593 if (str_find(&ctl->antispam, smtperr))
596 * SMTP listener explicitly refuses to deliver mail
597 * coming from this address, probably due to an
598 * anti-spam domain exclusion. Respect this. Don't
599 * try to ship the message, and don't prevent it from
600 * being deleted. Typical values:
602 * 501 = exim's old antispam response
603 * 550 = exim's new antispam response (temporary)
604 * 553 = sendmail 8.8.7's generic REJECT
605 * 571 = sendmail's "unsolicited email refused"
609 "We do not accept mail from you.\r\n",
615 * Suppress error message only if the response specifically
616 * meant `excluded for policy reasons'. We *should* see
617 * an error when the return code is less specific.
620 error(0, -1, _("%cMTP error: %s"),
626 case 452: /* insufficient system storage */
628 * Temporary out-of-queue-space condition on the
629 * ESMTP server. Don't try to ship the message,
630 * and suppress deletion so it can be retried on
631 * a future retrieval cycle.
633 * Bouncemail *might* be appropriate here as a delay
634 * notification. But it's not really necessary because
635 * this is not an actual failure, we're very likely to be
636 * able to recover on the next cycle.
638 return(PS_TRANSIENT);
640 case 552: /* message exceeds fixed maximum message size */
642 * Permanent no-go condition on the
643 * ESMTP server. Don't try to ship the message,
644 * and allow it to be deleted.
647 "This message was too large.\r\n",
651 case 553: /* invalid sending domain */
653 * These latter days 553 usually means a spammer is trying to
657 "Invalid address.\r\n",
661 default: /* bounce the error back to the sender */
663 "General SMTP/ESMTP error.\r\n",
670 * Now list the recipient addressees
672 for (idp = msg->recipients; idp; idp = idp->next)
673 if (idp->val.status.mark == XMIT_ACCEPT)
675 if (strchr(idp->id, '@'))
676 strcpy(addr, idp->id);
679 snprintf(addr, sizeof(addr)-1, "%s@%s", idp->id, ctl->destaddr);
681 sprintf(addr, "%s@%s", idp->id, ctl->destaddr);
682 #endif /* HAVE_SNPRINTF */
684 if (SMTP_rcpt(ctl->smtp_socket, addr) == SM_OK)
689 idp->val.status.mark = XMIT_ANTISPAM;
691 _("%cMTP listener doesn't like recipient address `%s'"),
692 ctl->listener, addr);
695 if (!(*good_addresses))
698 snprintf(addr, sizeof(addr)-1, "%s@%s", run.postmaster, ctl->destaddr);
700 sprintf(addr, "%s@%s", run.postmaster, ctl->destaddr);
701 #endif /* HAVE_SNPRINTF */
703 if (SMTP_rcpt(ctl->smtp_socket, addr) != SM_OK)
705 error(0, 0, _("can't even send to %s!"), run.postmaster);
706 SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
711 /* tell it we're ready to send data */
712 SMTP_data(ctl->smtp_socket);
716 * We need to stash this away in order to know how many
717 * response lines to expect after the LMTP end-of-message.
719 msg->lmtp_responses = *good_addresses;
724 void release_sink(struct query *ctl)
725 /* release the per-message output sink, whether it's a pipe or SMTP socket */
734 sinkfp = (FILE *)NULL;
736 signal(SIGCHLD, sigchld);
740 int close_sink(struct query *ctl, struct msgblk *msg, flag forward)
741 /* perform end-of-message actions on the current output sink */
747 /* close the delivery pipe, we'll reopen before next message */
751 sinkfp = (FILE *)NULL;
755 signal(SIGCHLD, sigchld);
758 error(0, -1, _("MDA exited abnormally or returned nonzero status"));
764 /* implicit disk-full check here... */
765 fputs("..\r\n", sinkfp);
766 if (strcmp(ctl->bsmtp, "-"))
770 error(0, -1, _("Message termination or close of BSMTP file failed"));
776 /* write message terminator */
777 if (SMTP_eom(ctl->smtp_socket) != SM_OK)
779 error(0, -1, _("SMTP listener refused delivery"));
784 * If this is an SMTP connection, SMTP_eom() ate the response.
785 * But could be this is an LMTP connection, in which case we have to
786 * interpret either (a) a single 503 response meaning there
787 * were no successful RCPT TOs, or (b) a variable number of
788 * responses, one for each successful RCPT TO. We need to send
789 * bouncemail on each failed response and then return TRUE anyway,
790 * otherwise the message will get left in the queue and resent
791 * to people who got it the first time.
793 if (ctl->listener == LMTP_MODE)
794 if (msg->lmtp_responses == 0)
796 SMTP_ok(ctl->smtp_socket);
799 * According to RFC2033, 503 is the only legal response
800 * if no RCPT TO commands succeeded. No error recovery
801 * is really possible here, as we have no idea what
802 * insane thing the listener might be doing if it doesn't
805 if (atoi(smtp_response) == 503)
806 error(0, -1, _("LMTP delivery error on EOM"));
809 _("Unexpected non-503 response to LMTP EOM: %s"),
813 * It's not completely clear what to do here. We choose to
814 * interpret delivery failure here as a transient error,
815 * the same way SMTP delivery failure is handled. If we're
816 * wrong, an undead message will get stuck in the queue.
825 /* eat the RFC2033-required responses, saving errors */
826 xalloca(responses, char **, sizeof(char *) * msg->lmtp_responses);
827 for (errors = i = 0; i < msg->lmtp_responses; i++)
829 if (SMTP_ok(ctl->smtp_socket) == SM_OK)
830 responses[i] = (char *)NULL;
833 xalloca(responses[errors],
835 strlen(smtp_response)+1);
836 strcpy(responses[errors], smtp_response);
842 return(TRUE); /* all deliveries succeeded */
845 * One or more deliveries failed.
846 * If we can bounce a failures list back to the sender,
847 * return TRUE, deleting the message from the server so
848 * it won't be re-forwarded on subsequent poll cycles.
850 return(send_bouncemail(msg,
851 "LSMTP partial delivery failure.\r\n",
859 int open_warning_by_mail(struct query *ctl, struct msgblk *msg)
860 /* set up output sink for a mailed warning to calling user */
865 * Dispatching warning email is a little complicated. The problem is
866 * that we have to deal with three distinct cases:
868 * 1. Single-drop running from user account. Warning mail should
869 * go to the local name for which we're collecting (coincides
870 * with calling user).
872 * 2. Single-drop running from root or other privileged ID, with rc
873 * file generated on the fly (Ken Estes's weird setup...) Mail
874 * should go to the local name for which we're collecting (does not
875 * coincide with calling user).
877 * 3. Multidrop. Mail must go to postmaster. We leave the recipients
878 * member null so this message will fall through to run.postmaster.
880 * The zero in the reallen element means we won't pass a SIZE
881 * option to ESMTP; the message length would be more trouble than
882 * it's worth to compute.
884 struct msgblk reply = {NULL, NULL, "FETCHMAIL-DAEMON", 0};
886 if (!MULTIDROP(ctl)) /* send to calling user */
890 save_str(&reply.recipients, ctl->localnames->id, XMIT_ACCEPT);
891 status = open_sink(ctl, &reply, &good, &bad);
892 free_str_list(&reply.recipients);
895 else /* send to postmaster */
896 return(open_sink(ctl, &reply, &good, &bad));
899 #if defined(HAVE_STDARG_H)
900 void stuff_warning(struct query *ctl, const char *fmt, ... )
902 void stuff_warning(struct query *ctl, fmt, va_alist)
904 const char *fmt; /* printf-style format */
907 /* format and ship a warning message line by mail */
909 char buf[POPBUFSIZE];
913 * stuffline() requires its input to be writeable (for CR stripping),
914 * so we needed to copy the message to a writeable buffer anyway in
915 * case it was a string constant. We make a virtue of that necessity
916 * here by supporting stdargs/varargs.
918 #if defined(HAVE_STDARG_H)
923 #ifdef HAVE_VSNPRINTF
924 vsnprintf(buf, sizeof(buf), fmt, ap);
926 vsprintf(buf, fmt, ap);
935 void close_warning_by_mail(struct query *ctl, struct msgblk *msg)
936 /* sign and send mailed warnings */
938 stuff_warning(ctl, "--\r\n\t\t\t\tThe Fetchmail Daemon\r\n");
939 close_sink(ctl, msg, TRUE);
942 /* sink.c ends here */