1b6bf56d1d2eba734c1f217b456a8205090f5bc3
[exim.git] / src / src / header.c
1 /* $Cambridge: exim/src/src/header.c,v 1.8 2009/11/16 19:50:37 nm4 Exp $ */
2
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
6
7 /* Copyright (c) University of Cambridge 1995 - 2009 */
8 /* See the file NOTICE for conditions of use and distribution. */
9
10
11 #include "exim.h"
12
13
14 /*************************************************
15 * Test a header for matching name *
16 *************************************************/
17
18 /* This function tests the name of a header. It is made into a function because
19 it isn't just a string comparison: spaces and tabs are permitted between the
20 name and the colon. The h->text field should nowadays never be NULL, but check
21 it just in case.
22
23 Arguments:
24 h points to the header
25 name the name to test
26 len the length of the name
27 notdel if TRUE, force FALSE for deleted headers
28
29 Returns: TRUE or FALSE
30 */
31
32 BOOL
33 header_testname(header_line *h, uschar *name, int len, BOOL notdel)
34 {
35 uschar *tt;
36 if (h->type == '*' && notdel) return FALSE;
37 if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE;
38 tt = h->text + len;
39 while (*tt == ' ' || *tt == '\t') tt++;
40 return *tt == ':';
41 }
42
43 /* This is a copy of the function above, only that it is possible to pass
44 only the beginning of a header name. It simply does a front-anchored
45 substring match. Arguments and Return codes are the same as for
46 header_testname() above. */
47
48 BOOL
49 header_testname_incomplete(header_line *h, uschar *name, int len, BOOL notdel)
50 {
51 if (h->type == '*' && notdel) return FALSE;
52 if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE;
53 return TRUE;
54 }
55
56
57 /*************************************************
58 * Add new header backend function *
59 *************************************************/
60
61 /* The header_last variable points to the last header during message reception
62 and delivery; otherwise it is NULL. We add new headers only when header_last is
63 not NULL. The function may get called sometimes when it is NULL (e.g. during
64 address verification where rewriting options exist). When called from a filter,
65 there may be multiple header lines in a single string.
66
67 This is an internal static function that is the common back end to the external
68 functions defined below. The general interface allows the header to be inserted
69 before or after a given occurrence of a given header.
70
71 (a) if "name" is NULL, the header is added at the end of all the existing
72 headers if "after" is true, or at the start if it is false. The "topnot"
73 flag is not used.
74
75 (b) If "name" is not NULL, the first existing header with that name is sought.
76 If "after" is false, the new header is added before it. If "after" is true,
77 a check is made for adjacent headers with the same name, and the new header
78 is added after the last of them. If a header of the given name is not
79 found, the new header is added first if "topnot" is true, and at the bottom
80 otherwise.
81
82 Arguments:
83 after TRUE for "after", FALSE for "before"
84 name name if adding at a specific header, else NULL
85 topnot TRUE to add at top if no header found
86 type Exim header type character (htype_something)
87 format sprintf format
88 ap va_list value for format arguments
89
90 Returns: nothing
91 */
92
93 static void
94 header_add_backend(BOOL after, uschar *name, BOOL topnot, int type,
95 char *format, va_list ap)
96 {
97 header_line *h, *new;
98 header_line **hptr;
99
100 uschar *p, *q;
101 uschar buffer[HEADER_ADD_BUFFER_SIZE];
102
103 if (header_last == NULL) return;
104
105 if (!string_vformat(buffer, sizeof(buffer), format, ap))
106 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "string too long in header_add: "
107 "%.100s ...", buffer);
108
109 /* Find where to insert this header */
110
111 if (name == NULL)
112 {
113 if (after)
114 {
115 hptr = &(header_last->next);
116 h = NULL;
117 }
118 else
119 {
120 hptr = &header_list;
121
122 /* header_list->text can be NULL if we get here between when the new
123 received header is allocated and when it is acutally filled in. We want
124 that header to be first, so skip it for now. */
125
126 if (header_list->text == NULL)
127 hptr = &header_list->next;
128 h = *hptr;
129 }
130 }
131
132 else
133 {
134 int len = Ustrlen(name);
135
136 /* Find the first non-deleted header witht the correct name. */
137
138 for (hptr = &header_list; (h = *hptr) != NULL; hptr = &(h->next))
139 {
140 if (header_testname(h, name, len, TRUE)) break;
141 }
142
143 /* Handle the case where no header is found. To insert at the bottom, nothing
144 needs to be done. */
145
146 if (h == NULL)
147 {
148 if (topnot)
149 {
150 hptr = &header_list;
151 h = header_list;
152 }
153 }
154
155 /* Handle the case where a header is found. Check for more if "after" is
156 true. In this case, we want to include deleted headers in the block. */
157
158 else if (after)
159 {
160 for (;;)
161 {
162 if (h->next == NULL || !header_testname(h, name, len, FALSE)) break;
163 hptr = &(h->next);
164 h = h->next;
165 }
166 }
167 }
168
169 /* Loop for multiple header lines, taking care about continuations. At this
170 point, we have hptr pointing to the link field that will point to the new
171 header, and h containing the following header, or NULL. */
172
173 for (p = q = buffer; *p != 0; )
174 {
175 for (;;)
176 {
177 q = Ustrchr(q, '\n');
178 if (q == NULL) q = p + Ustrlen(p);
179 if (*(++q) != ' ' && *q != '\t') break;
180 }
181
182 new = store_get(sizeof(header_line));
183 new->text = string_copyn(p, q - p);
184 new->slen = q - p;
185 new->type = type;
186 new->next = h;
187
188 *hptr = new;
189 hptr = &(new->next);
190
191 if (h == NULL) header_last = new;
192 p = q;
193 }
194 }
195
196
197 /*************************************************
198 * Add new header anywhere in the chain *
199 *************************************************/
200
201 /* This is an external interface to header_add_backend().
202
203 Arguments:
204 after TRUE for "after", FALSE for "before"
205 name name if adding at a specific header, else NULL
206 topnot TRUE to add at top if no header found
207 type Exim header type character (htype_something)
208 format sprintf format
209 ... format arguments
210
211 Returns: nothing
212 */
213
214 void
215 header_add_at_position(BOOL after, uschar *name, BOOL topnot, int type,
216 char *format, ...)
217 {
218 va_list ap;
219 va_start(ap, format);
220 header_add_backend(after, name, topnot, type, format, ap);
221 va_end(ap);
222 }
223
224
225
226 /*************************************************
227 * Add new header on end of chain *
228 *************************************************/
229
230 /* This is now a convenience interface to header_add_backend().
231
232 Arguments:
233 type Exim header type character
234 format sprintf format
235 ... arguments for the format
236
237 Returns: nothing
238 */
239
240 void
241 header_add(int type, char *format, ...)
242 {
243 va_list ap;
244 va_start(ap, format);
245 header_add_backend(TRUE, NULL, FALSE, type, format, ap);
246 va_end(ap);
247 }
248
249
250
251 /*************************************************
252 * Remove (mark as old) a header *
253 *************************************************/
254
255 /* This function is used by the filter code; it is also exported in the
256 local_scan() API. If no header is found, the function does nothing.
257
258 Arguments:
259 occ the occurrence number for multiply-defined headers
260 <= 0 means "all"; deleted headers are not counted
261 name the header name
262
263 Returns: nothing
264 */
265
266 void
267 header_remove(int occ, uschar *name)
268 {
269 header_line *h;
270 int hcount = 0;
271 int len = Ustrlen(name);
272 for (h = header_list; h != NULL; h = h->next)
273 {
274 if (header_testname(h, name, len, TRUE) && (occ <= 0 || ++hcount == occ))
275 {
276 h->type = htype_old;
277 if (occ > 0) return;
278 }
279 }
280 }
281
282
283
284 /*************************************************
285 * Check the name of a header *
286 *************************************************/
287
288 /* This function scans a table of header field names that Exim recognizes, and
289 returns the identification of a match. If "resent" is true, the header is known
290 to start with "resent-". In that case, the function matches only those fields
291 that are allowed to appear with resent- in front of them.
292
293 Arguments:
294 h points to the header line
295 is_resent TRUE if the name starts "Resent-"
296
297 Returns: One of the htype_ enum values, identifying the header
298 */
299
300 int
301 header_checkname(header_line *h, BOOL is_resent)
302 {
303 uschar *text = h->text;
304 header_name *bot = header_names;
305 header_name *top = header_names + header_names_size;
306
307 if (is_resent) text += 7;
308
309 while (bot < top)
310 {
311 header_name *mid = bot + (top - bot)/2;
312 int c = strncmpic(text, mid->name, mid->len);
313
314 if (c == 0)
315 {
316 uschar *s = text + mid->len;
317 while (isspace(*s)) s++;
318 if (*s == ':')
319 return (!is_resent || mid->allow_resent)? mid->htype : htype_other;
320 c = 1;
321 }
322
323 if (c > 0) bot = mid + 1; else top = mid;
324 }
325
326 return htype_other;
327 }
328
329
330 /*************************************************
331 * Scan a header for certain strings *
332 *************************************************/
333
334 /* This function is used for the "personal" test. It scans a particular header
335 line for any one of a number of strings, matched caselessly either as plain
336 strings, or as regular expressions. If the header line contains a list of
337 addresses, each match is applied only to the operative part of each address in
338 the header, and non-regular expressions must be exact matches.
339
340 The patterns can be provided either as a chain of string_item structures, or
341 inline in the argument list, or both. If there is more than one header of the
342 same name, they are all searched.
343
344 Arguments:
345 name header name, including the trailing colon
346 has_addresses TRUE if the header contains a list of addresses
347 cond value to return if the header contains any of the strings
348 strings points to a chain of string_item blocks
349 count number of inline strings
350 ... the inline strings
351
352 Returns: cond if the header exists and contains one of the strings;
353 otherwise !cond
354 */
355
356
357 /* First we have a local subroutine to handle a single pattern */
358
359 static BOOL
360 one_pattern_match(uschar *name, int slen, BOOL has_addresses, uschar *pattern)
361 {
362 BOOL yield = FALSE;
363 header_line *h;
364 const pcre *re = NULL;
365
366 /* If the pattern is a regex, compile it. Bomb out if compiling fails; these
367 patterns are all constructed internally and should be valid. */
368
369 if (*pattern == '^') re = regex_must_compile(pattern, TRUE, FALSE);
370
371 /* Scan for the required header(s) and scan each one */
372
373 for (h = header_list; !yield && h != NULL; h = h->next)
374 {
375 if (h->type == htype_old || slen > h->slen ||
376 strncmpic(name, h->text, slen) != 0)
377 continue;
378
379 /* If the header is a list of addresses, extract each one in turn, and scan
380 it. A non-regex scan must be an exact match for the address. */
381
382 if (has_addresses)
383 {
384 uschar *s = h->text + slen;
385
386 while (!yield && *s != 0)
387 {
388 uschar *error, *next;
389 uschar *e = parse_find_address_end(s, FALSE);
390 int terminator = *e;
391 int start, end, domain;
392
393 /* Temporarily terminate the string at the address end while extracting
394 the operative address within. */
395
396 *e = 0;
397 next = parse_extract_address(s, &error, &start, &end, &domain, FALSE);
398 *e = terminator;
399
400 /* Move on, ready for the next address */
401
402 s = e;
403 if (*s == ',') s++;
404
405 /* If there is some kind of syntax error, just give up on this header
406 line. */
407
408 if (next == NULL) break;
409
410 /* Otherwise, test for the pattern; a non-regex must be an exact match */
411
412 yield = (re == NULL)?
413 (strcmpic(next, pattern) == 0)
414 :
415 (pcre_exec(re, NULL, CS next, Ustrlen(next), 0, PCRE_EOPT, NULL, 0)
416 >= 0);
417 }
418 }
419
420 /* For headers that are not lists of addresses, scan the entire header line,
421 and just require "contains" for non-regex patterns. */
422
423 else
424 {
425 yield = (re == NULL)?
426 (strstric(h->text, pattern, FALSE) != NULL)
427 :
428 (pcre_exec(re, NULL, CS h->text, h->slen, 0, PCRE_EOPT, NULL, 0) >= 0);
429 }
430 }
431
432 return yield;
433 }
434
435
436 /* The externally visible interface */
437
438 BOOL
439 header_match(uschar *name, BOOL has_addresses, BOOL cond, string_item *strings,
440 int count, ...)
441 {
442 va_list ap;
443 string_item *s;
444 int i;
445 int slen = Ustrlen(name);
446
447 for (s = strings; s != NULL; s = s->next)
448 {
449 if (one_pattern_match(name, slen, has_addresses, s->text)) return cond;
450 }
451
452 va_start(ap, count);
453 for (i = 0; i < count; i++)
454 {
455 if (one_pattern_match(name, slen, has_addresses, va_arg(ap, uschar *)))
456 return cond;
457 }
458 va_end(ap);
459
460 return !cond;
461 }
462
463 /* End of header.c */