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 /* Functions concerned with rewriting headers */
13 /* Names for testing rewriting */
15 static const char *rrname[] = {
26 /* Structure and table for finding source of address for debug printing */
28 typedef struct where_list_block {
33 static where_list_block where_list[] = {
34 { rewrite_sender, CUS"sender:" },
35 { rewrite_from, CUS"from:" },
36 { rewrite_to, CUS"to:" },
37 { rewrite_cc, CUS"cc:" },
38 { rewrite_bcc, CUS"bcc:" },
39 { rewrite_replyto, CUS"reply-to:" },
40 { rewrite_envfrom, CUS"env-from" },
41 { rewrite_envto, CUS"env-to" },
42 { rewrite_smtp, CUS"smtp recipient" },
43 { rewrite_smtp|rewrite_smtp_sender, CUS"smtp sender" }
46 static int where_list_size = sizeof(where_list)/sizeof(where_list_block);
50 /*************************************************
51 * Ensure an address is qualified *
52 *************************************************/
57 is_recipient TRUE if a recipient address; FALSE if a sender address
59 Returns: fully-qualified address
63 rewrite_address_qualify(uschar *s, BOOL is_recipient)
65 return (parse_find_at(s) != NULL)? s :
66 string_sprintf("%s@%s", s,
67 is_recipient? qualify_domain_recipient : qualify_domain_sender);
72 /*************************************************
73 * Rewrite a single address *
74 *************************************************/
76 /* The yield is the input address if there is no rewriting to be done. Assume
77 the input is a valid address, except in the case of SMTP-time rewriting, which
78 is handled specially. When this function is called while processing filter and
79 forward files, the uid may be that of the user. Ensure it is reset while
80 expanding a replacement, in case that involves file lookups.
84 flag indicates where this address comes from; it must match the
85 flags in the rewriting rule
86 whole if not NULL, set TRUE if any rewriting rule contained the
87 "whole" bit and it is a header that is being rewritten
88 add_header if TRUE and rewriting occurs, add an "X-rewrote-xxx" header
89 if headers are in existence; this should be TRUE only when
90 a message is being received, not during delivery
91 name name of header, for use when adding X-rewrote-xxxx
92 rewrite_rules chain of rewriting rules
94 Returns: new address if rewritten; the input address if no change;
95 for a header rewrite, if the "whole" bit is set, the entire
96 rewritten address is returned, not just the active bit.
100 rewrite_one(uschar *s, int flag, BOOL *whole, BOOL add_header, uschar *name,
101 rewrite_rule *rewrite_rules)
106 uschar *domain = NULL;
109 int yield_start = 0, yield_end = 0;
111 if (whole != NULL) *whole = FALSE;
113 /* Scan the rewriting rules */
115 for (rule = rewrite_rules;
116 rule != NULL && !done;
117 rule_number++, rule = rule->next)
119 int start, end, pdomain;
121 uschar *save_localpart;
122 const uschar *save_domain;
123 uschar *error, *new, *newparsed;
125 /* Ensure that the flag matches the flags in the rule. */
127 if ((rule->flags & flag) == 0) continue;
129 /* Come back here for a repeat after a successful rewrite. We do this
130 only so many times. */
134 /* If this is an SMTP-time rewrite, the pattern must be a regex and
135 the subject may have any structure. No local part or domain variables
136 can be set for the expansion. We expand the pattern in order to be consistent
137 with the other kinds of rewrite, where expansion happens inside
138 match_address_list(). */
140 if ((flag & rewrite_smtp) != 0)
142 uschar *key = expand_string(rule->key);
145 if (!expand_string_forcedfail)
146 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand \"%s\" while "
147 "checking for SMTP rewriting: %s", rule->key, expand_string_message);
150 if (match_check_string(subject, key, 0, TRUE, FALSE, FALSE, NULL) != OK)
152 new = expand_string(rule->replacement);
155 /* All other rewrites expect the input to be a valid address, so local part
156 and domain variables can be set for expansion. For the first rule, to be
157 applied to this address, domain will be NULL and needs to be set. */
161 if (domain == NULL) domain = Ustrrchr(subject, '@') + 1;
163 /* Use the general function for matching an address against a list (here
164 just one item, so use the "impossible value" separator UCHAR_MAX+1). */
166 if (match_address_list(subject, FALSE, TRUE, CUSS &(rule->key), NULL, 0,
167 UCHAR_MAX + 1, NULL) != OK)
170 /* The source address matches, and numerical variables have been
171 set up. If the replacement string consists of precisely "*" then no
172 rewriting is required for this address - the behaviour is as for "fail"
173 in the replacement expansion, but assuming the quit flag. */
175 if (Ustrcmp(rule->replacement, "*") == 0) break;
177 /* Otherwise, expand the replacement string. Set $local_part and $domain to
178 the appropriate values, restoring whatever value they previously had
181 save_localpart = deliver_localpart;
182 save_domain = deliver_domain;
184 /* We have subject pointing to "localpart@domain" and domain pointing to
185 the domain. Temporarily terminate the local part so that it can be
186 set up as an expansion variable */
189 deliver_localpart = subject;
190 deliver_domain = domain;
192 new = expand_string(rule->replacement);
195 deliver_localpart = save_localpart;
196 deliver_domain = save_domain;
199 /* If the expansion failed with the "forcedfail" flag, don't generate
200 an error - just give up on this rewriting rule. If the "q" flag is set,
201 give up altogether. For other expansion failures we have a configuration
206 if (expand_string_forcedfail)
207 { if ((rule->flags & rewrite_quit) != 0) break; else continue; }
208 log_write(0, LOG_MAIN|LOG_PANIC, "Expansion of %s failed while rewriting: "
209 "%s", rule->replacement, expand_string_message);
213 /* Check the what has been generated is a valid RFC 2822 address. Only
214 envelope from or SMTP sender is permitted to be rewritten as <>.*/
216 newparsed = parse_extract_address(new, &error, &start, &end, &pdomain,
217 flag == rewrite_envfrom || flag == (rewrite_smtp|rewrite_smtp_sender));
219 if (newparsed == NULL)
221 log_write(0, LOG_MAIN|LOG_PANIC, "Rewrite of %s yielded unparseable "
222 "address: %s in address %s", subject, error, new);
223 break; /* Give up on this address */
226 /* A non-null unqualified address can be qualified if requested. Otherwise,
227 this is an error unless it's the empty address in circumstances where that is
230 if (pdomain == 0 && (*newparsed != 0 ||
231 (flag != rewrite_envfrom && flag != (rewrite_smtp|rewrite_smtp_sender))))
233 if ((rule->flags & rewrite_qualify) != 0)
235 newparsed = rewrite_address_qualify(newparsed, TRUE);
236 new = string_sprintf("%.*s%s%.*s", start, new, newparsed,
237 Ustrlen(new) - end, new + end);
238 end = start + Ustrlen(newparsed);
242 log_write(0, LOG_MAIN|LOG_PANIC, "Rewrite of %s yielded unqualified "
243 "address \"%s\"", subject, new);
244 break; /* Give up on this address */
248 /* We have a validly rewritten address */
250 if (LOGGING(address_rewrite) || (debug_selector & D_rewrite) != 0)
253 const uschar *where = CUS"?";
255 for (i = 0; i < where_list_size; i++)
257 if (flag == where_list[i].bit)
259 where = where_list[i].string;
263 log_write(L_address_rewrite,
264 LOG_MAIN, "\"%s\" from %s rewritten as \"%s\" by rule %d",
265 yield, where, new, rule_number);
268 /* A header will only actually be added if header_last is non-NULL,
269 i.e. during message reception or delivery, but add_header should not
270 be set TRUE during delivery, as otherwise multiple instances of the header
271 can fill up the -H file and make it embarrassingly large. We don't need
272 to set header_rewritten because the -H file always gets written at the end
273 of message reception. */
276 header_add(htype_old, "X-rewrote-%s: %s\n", name, subject);
278 /* Handle the case when replacement of the whole address is possible.
279 This happens only when whole is not NULL and we are rewriting a header.
280 If *whole is already TRUE it means that a previous rule had the w
281 flag set and so we must preserve the non-active portion of the current
282 subject unless the current rule also has the w flag set. */
284 if (whole != NULL && (flag & rewrite_all_headers) != 0)
286 /* Current rule has the w flag set. We must ensure the phrase parts
287 are syntactically valid if they are present. */
289 if ((rule->flags & rewrite_whole) != 0)
291 if (start > 0 && new[start-1] == '<')
293 uschar *p1 = new + start - 1;
294 uschar *p2 = new + end + 1;
295 const uschar *pf1, *pf2;
296 uschar buff1[256], buff2[256];
298 while (p1 > new && p1[-1] == ' ') p1--;
299 pf1 = parse_fix_phrase(new, p1 - new, buff1, sizeof(buff1));
300 while (*p2 == ' ') p2++;
301 pf2 = parse_fix_phrase(p2, Ustrlen(p2), buff2, sizeof(buff2));
303 /* Note that pf1 and pf2 are NOT necessarily buff1 and buff2. For
304 a non-RFC 2047 phrase that does not need to be RFC 2822 quoted, they
305 will be buff1+1 and buff2+1. */
307 start = Ustrlen(pf1) + start + new - p1;
308 end = start + Ustrlen(newparsed);
309 new = string_sprintf("%s%.*s%s", pf1, p2 - p1, p1, pf2);
312 /* Now accept the whole thing */
321 /* Current rule does not have the w flag set; if not previously
322 done any whole rewriting, behave in non-whole manner. */
324 else if (!*whole) goto NEVER_WHOLE;
326 /* Current rule does not have the w flag set, but a previous
327 rule did rewrite the whole address. Thus yield and subject will be
328 different. Preserve the previous non-active part of the address. */
333 new = string_sprintf("%.*s%s%n%s",
334 yield_start, yield, subject, &end, yield + yield_end);
340 /* Rule just rewrites active part, or handling an envelope. This
341 code is obeyed only when all rules so far have not done "whole"
347 subject = yield = newparsed;
350 domain = NULL; /* Reset for next rule */
352 /* If no further rewrites are to be done, set the done flag. This allows
353 repeats of the current rule if configured before breaking the loop. */
355 if ((rule->flags & rewrite_quit) != 0) done = TRUE;
357 /* Allow the current rule to be applied up to 10 times if
360 if ((rule->flags & rewrite_repeat) != 0)
362 if (count++ < 10) goto REPEAT_RULE;
363 log_write(0, LOG_MAIN|LOG_PANIC, "rewrite rule repeat ignored after 10 "
368 /* Unset expansion numeric variables, and that's it. */
376 /*************************************************
377 * Ensure qualification and rewrite *
378 *************************************************/
380 /* This function is called for envelope addresses, the boolean specifying
381 whether a recipient or a sender. It must first of all ensure the address is
382 fully qualified, and then apply any relevant re-writing rules. The add-header
383 flag causes a header to be added, recording the old address. This is marked
384 "old", so that it is never transported anywhere; it exists for local checking
385 and debugging purposes.
388 s the address to be considered
389 is_recipient TRUE for recipient addresses; FALSE otherwise
390 add_header add "X-rewrote-xxx" header when rewriting; this is
391 set TRUE only for calls from the reception functions
392 rewrite_rules points to chain of rewrite rules
393 existflags bits indicating which headers there are rewrites for
394 (just an optimisation)
396 Returns: possibly rewritten address
400 rewrite_address(uschar *s, BOOL is_recipient, BOOL add_header,
401 rewrite_rule *rewrite_rules, int existflags)
403 int flag = is_recipient? rewrite_envto : rewrite_envfrom;
404 s = rewrite_address_qualify(s, is_recipient);
405 if ((existflags & flag) != 0)
407 uschar *new = rewrite_one(s, flag, NULL, add_header, is_recipient?
408 US"original-recipient" : US"sender", rewrite_rules);
409 if (new != s) s = new;
416 /*************************************************
417 * Qualify and possibly rewrite one header *
418 *************************************************/
420 /* This is called only from rewrite_header() below, either when reading a
421 message. or when routing, in order to rewrite addresses that get changed by a
422 router. This is normally the addition of full qualification to a partial
423 domain. The first rewriting rule in this case is "change routed_old into
424 routed_new", and it applies to all header lines that contain addresses. Then
425 header-specific rewriting rules are applied.
427 Before rewriting can be done, addresses without domains have to be qualified.
428 This should only be done for messages from "local" senders. This is a difficult
429 concept to pin down, what with the use of SMTP both as a submission and as a
430 transmission protocol. Exim normally requires incoming SMTP to contain fully-
431 qualified addresses, but there are options to permit unqualified ones from
432 certain hosts. For those hosts only, addresses in headers can also be
433 qualified. For other hosts, unqualified addresses in headers do not get touched
434 in any way. For locally sourced messages, unqualified addresses always get
435 qualified, except when -bnq is used to explicitly suppress this.
438 h pointer to header line block
439 flag indicates which header this is
440 routed_old if not NULL, this is a rewrite caused by a router, changing
441 this domain into routed_new
442 routed_new new routed domain if routed_old is not NULL
443 rewrite_rules points to chain of rewriting rules
444 existflags bits indicating which rewrites exist
445 replace if TRUE, insert the new header in the chain after the old
446 one, and mark the old one "replaced"
448 Returns: NULL if header unchanged; otherwise the rewritten header
452 rewrite_one_header(header_line *h, int flag,
453 const uschar *routed_old, const uschar *routed_new,
454 rewrite_rule *rewrite_rules, int existflags, BOOL replace)
457 header_line *newh = NULL;
458 void *function_reset_point = store_get(0);
459 uschar *s = Ustrchr(h->text, ':') + 1;
460 while (isspace(*s)) s++;
463 debug_printf("rewrite_one_header: type=%c:\n %s", h->type, h->text);
465 parse_allow_group = TRUE; /* Allow group syntax */
467 /* Loop for multiple addresses in the header. We have to go through them all
468 in case any need qualifying, even if there's no rewriting. Pathological headers
469 may have thousands of addresses in them, so cause the store to be reset for
470 any that don't actually get rewritten. We also play silly games for those that
471 _are_ rewritten so as to avoid runaway store usage for these kinds of header.
472 We want to avoid keeping store for any intermediate versions. */
477 uschar *ss = parse_find_address_end(s, FALSE);
478 uschar *recipient, *new, *errmess;
479 void *loop_reset_point = store_get(0);
480 BOOL changed = FALSE;
481 int terminator = *ss;
482 int start, end, domain;
484 /* Temporarily terminate the string at this point, and extract the
485 operative address within. Then put back the terminator and prepare for
486 the next address, saving the start of the old one. */
489 recipient = parse_extract_address(s,&errmess,&start,&end,&domain,FALSE);
492 s = ss + (terminator? 1:0);
493 while (isspace(*s)) s++;
495 /* There isn't much we can do for syntactic disasters at this stage.
496 Pro tem (possibly for ever) ignore them. */
498 if (recipient == NULL)
500 store_reset(loop_reset_point);
504 /* If routed_old is not NULL, this is a rewrite caused by a router,
505 consisting of changing routed_old into routed_new, and applying to all
506 headers. If the header address has no domain, it is excluded, since a router
507 rewrite affects domains only. The new value should always be fully qualified,
508 but it may be something that has an explicit re-write rule set, so we need to
509 check the configured rules subsequently as well. (Example: there's an
510 explicit rewrite turning *.foo.com into foo.com, and an address is supplied
511 as abc@xyz, which the DNS lookup turns into abc@xyz.foo.com). However, if no
512 change is made here, don't bother carrying on. */
514 if (routed_old != NULL)
516 if (domain <= 0 || strcmpic(recipient+domain, routed_old) != 0) continue;
517 recipient[domain-1] = 0;
518 new = string_sprintf("%s@%s", recipient, routed_new);
521 recipient[domain-1] = '@';
522 debug_printf("%s rewritten by router as %s\n", recipient, new);
528 /* This is not a router-inspired rewrite. Ensure the address is fully
529 qualified if that is permitted. If an unqualified address was received
530 from a host that isn't listed, do not continue rewriting this address.
531 Sender, From or Reply-To headers are treated as senders, the rest as
532 recipients. This matters only when there are different qualify strings. */
537 (flag & (rewrite_sender | rewrite_from | rewrite_replyto)) == 0;
538 new = rewrite_address_qualify(recipient, is_recipient);
539 changed = (new != recipient);
542 /* Can only qualify if permitted; if not, no rewrite. */
544 if (changed && ((is_recipient && !allow_unqualified_recipient) ||
545 (!is_recipient && !allow_unqualified_sender)))
547 store_reset(loop_reset_point);
552 /* If there are rewrite rules for this type of header, apply
553 them. This test is just for efficiency, to save scanning the rules
554 in cases when nothing is going to change. If any rewrite rule had the
555 "whole" flag set, adjust the pointers so that the whole address gets
556 replaced, except possibly a final \n. */
558 if ((existflags & flag) != 0)
561 new = rewrite_one(recipient, flag, &whole, FALSE, NULL, rewrite_rules);
562 if (new != recipient)
569 if (sprev[end-1] == '\n') end--;
574 /* If nothing has changed, lose all dynamic store obtained in this loop, and
575 move on to the next address. We can't reset to the function start store
576 point, because we may have a rewritten line from a previous time round the
579 if (!changed) store_reset(loop_reset_point);
581 /* If the address has changed, create a new header containing the
582 rewritten address. We do not need to set the chain pointers at this
583 stage. We want to avoid using more and more memory if the header is very long
584 and contains lots and lots of rewritten addresses. Therefore, we build the
585 new text string in malloc store, then at the end we reset dynamic store
586 before copying the new header to a new block (and then freeing the malloc
587 block). The header must end up in dynamic store so that it's freed at the end
588 of receiving a message. */
593 int newlen = Ustrlen(new);
594 int oldlen = end - start;
596 header_line *prev = (newh == NULL)? h : newh;
597 uschar *newt = store_malloc(prev->slen - oldlen + newlen + 4);
598 uschar *newtstart = newt;
600 int type = prev->type;
601 int slen = prev->slen - oldlen + newlen;
603 /* Build the new header text by copying the old and putting in the
604 replacement. This process may make the header substantially longer
605 than it was before - qualification of a list of bare addresses can
606 often do this - so we stick in a newline after the re-written address
607 if it has increased in length and ends more than 40 characters in. In
608 fact, the code is not perfect, since it does not scan for existing
609 newlines in the header, but it doesn't seem worth going to that
610 amount of trouble. */
612 Ustrncpy(newt, prev->text, sprev - prev->text + start);
613 newt += sprev - prev->text + start;
617 remlen = s - (sprev + end);
620 Ustrncpy(newt, sprev + end, remlen);
625 /* Must check that there isn't a newline here anyway; in particular, there
626 will be one at the very end of the header, where we DON'T want to insert
627 another one! The pointer s has been skipped over white space, so just
628 look back to see if the last non-space-or-tab was a newline. */
630 if (newlen > oldlen && newt - newtstart - lastnewline > 40)
633 while (p >= prev->text && (*p == ' ' || *p == '\t')) p--;
636 lastnewline = newt - newtstart;
637 Ustrcat(newt, "\n\t");
642 /* Finally, the remaining unprocessed addresses, if any. */
646 DEBUG(D_rewrite) debug_printf("newlen=%d newtype=%c newtext:\n%s",
647 slen, type, newtstart);
649 /* Compute the length of the rest of the header line before we possibly
650 flatten a previously rewritten copy. */
652 remlen = (s - prev->text) - oldlen + newlen;
654 /* We have the new text in a malloc block. That enables us to release all
655 the memory that has been used, back to the point at which the function was
656 entered. Then set up a new header in dynamic store. This will override a
657 rewritten copy from a previous time round this loop. */
659 store_reset(function_reset_point);
660 newh = store_get(sizeof(header_line));
663 newh->text = string_copyn(newtstart, slen);
664 store_free(newtstart);
666 /* Set up for scanning the rest of the header */
668 s = newh->text + remlen;
669 DEBUG(D_rewrite) debug_printf("remainder: %s", (*s == 0)? US"\n" : s);
673 parse_allow_group = FALSE; /* Reset group flags */
674 parse_found_group = FALSE;
676 /* If a rewrite happened and "replace" is true, put the new header into the
677 chain following the old one, and mark the old one as replaced. */
679 if (newh != NULL && replace)
681 newh->next = h->next;
682 if (newh->next == NULL) header_last = newh;
693 /*************************************************
694 * Rewrite a header line *
695 *************************************************/
697 /* This function may be passed any old header line. It must detect those which
698 contain addresses, then then apply any rewriting rules that apply. If
699 routed_old is NULL, only the configured rewriting rules are consulted.
700 Otherwise, the rewriting rule is "change routed_old into routed_new", and it
701 applies to all header lines that contain addresses. Then header-specific
702 rewriting rules are applied.
704 The old header line is flagged as "old". Old headers are saved on the spool for
705 debugging but are never sent to any recipients.
708 h header line to rewrite
709 routed_old if not NULL, this is a rewrite caused by a router, changing
710 this domain into routed_new
711 routed_new new routed domain if routed_old is not NULL
712 rewrite_rules points to chain of rewrite rules
713 existflags bits indicating which rewrites exist
714 replace if TRUE, the new header is inserted into the header chain
715 after the old one, and the old one is marked replaced
717 Returns: NULL if header unchanged; otherwise the rewritten header
721 rewrite_header(header_line *h,
722 const uschar *routed_old, const uschar *routed_new,
723 rewrite_rule *rewrite_rules, int existflags, BOOL replace)
728 return rewrite_one_header(h, rewrite_sender, routed_old, routed_new,
729 rewrite_rules, existflags, replace);
732 return rewrite_one_header(h, rewrite_from, routed_old, routed_new,
733 rewrite_rules, existflags, replace);
736 return rewrite_one_header(h, rewrite_to, routed_old, routed_new,
737 rewrite_rules, existflags, replace);
740 return rewrite_one_header(h, rewrite_cc, routed_old, routed_new,
741 rewrite_rules, existflags, replace);
744 return rewrite_one_header(h, rewrite_bcc, routed_old, routed_new,
745 rewrite_rules, existflags, replace);
748 return rewrite_one_header(h, rewrite_replyto, routed_old, routed_new,
749 rewrite_rules, existflags, replace);
757 /************************************************
758 * Test rewriting rules *
759 ************************************************/
761 /* Called from the mainline as a result of the -brw option. Test the
762 address for all possible cases.
764 Argument: the address to test
768 void rewrite_test(uschar *s)
770 uschar *recipient, *error;
771 int i, start, end, domain;
772 BOOL done_smtp = FALSE;
774 if (rewrite_existflags == 0)
776 printf("No rewrite rules are defined\n");
780 /* Do SMTP rewrite only if a rule with the S flag exists. Allow <> by
781 pretending it is a sender. */
783 if ((rewrite_existflags & rewrite_smtp) != 0)
785 uschar *new = rewrite_one(s, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
786 US"", global_rewrite_rules);
790 printf(" SMTP: <>\n");
792 printf(" SMTP: %s\n", new);
797 /* Do the other rewrites only if a rule without the S flag exists */
799 if ((rewrite_existflags & ~rewrite_smtp) == 0) return;
801 /* Qualify if necessary before extracting the address */
803 if (parse_find_at(s) == NULL)
804 s = string_sprintf("%s@%s", s, qualify_domain_recipient);
806 recipient = parse_extract_address(s, &error, &start, &end, &domain, FALSE);
808 if (recipient == NULL)
811 printf("Syntax error in %s\n%c%s\n", s, toupper(error[0]), error+1);
815 for (i = 0; i < 8; i++)
819 uschar *new = rewrite_one(recipient, flag, &whole, FALSE, US"",
820 global_rewrite_rules);
821 printf("%s: ", rrname[i]);
824 else if (whole || (flag & rewrite_all_headers) == 0)
825 printf("%s\n", CS new);
826 else printf("%.*s%s%s\n", start, s, new, s+end);
830 /* End of rewrite.c */