51aa9f953e6f4638300107b5d9f8e53df1fd34df
[exim.git] / src / src / header.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2016 */
6 /* See the file NOTICE for conditions of use and distribution. */
7
8
9 #include "exim.h"
10
11
12 /*************************************************
13 * Test a header for matching name *
14 *************************************************/
15
16 /* This function tests the name of a header. It is made into a function because
17 it isn't just a string comparison: spaces and tabs are permitted between the
18 name and the colon. The h->text field should nowadays never be NULL, but check
19 it just in case.
20
21 Arguments:
22 h points to the header
23 name the name to test
24 len the length of the name
25 notdel if TRUE, force FALSE for deleted headers
26
27 Returns: TRUE or FALSE
28 */
29
30 BOOL
31 header_testname(header_line *h, const uschar *name, int len, BOOL notdel)
32 {
33 uschar *tt;
34 if (h->type == '*' && notdel) return FALSE;
35 if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE;
36 tt = h->text + len;
37 while (*tt == ' ' || *tt == '\t') tt++;
38 return *tt == ':';
39 }
40
41 /* This is a copy of the function above, only that it is possible to pass
42 only the beginning of a header name. It simply does a front-anchored
43 substring match. Arguments and Return codes are the same as for
44 header_testname() above. */
45
46 BOOL
47 header_testname_incomplete(header_line *h, const uschar *name,
48 int len, BOOL notdel)
49 {
50 if (h->type == '*' && notdel) return FALSE;
51 if (h->text == NULL || strncmpic(h->text, name, len) != 0) return FALSE;
52 return TRUE;
53 }
54
55
56 /*************************************************
57 * Add new header backend function *
58 *************************************************/
59
60 /* The header_last variable points to the last header during message reception
61 and delivery; otherwise it is NULL. We add new headers only when header_last is
62 not NULL. The function may get called sometimes when it is NULL (e.g. during
63 address verification where rewriting options exist). When called from a filter,
64 there may be multiple header lines in a single string.
65
66 This is an internal static function that is the common back end to the external
67 functions defined below. The general interface allows the header to be inserted
68 before or after a given occurrence of a given header.
69
70 (a) if "name" is NULL, the header is added at the end of all the existing
71 headers if "after" is true, or at the start if it is false. The "topnot"
72 flag is not used.
73
74 (b) If "name" is not NULL, the first existing header with that name is sought.
75 If "after" is false, the new header is added before it. If "after" is true,
76 a check is made for adjacent headers with the same name, and the new header
77 is added after the last of them. If a header of the given name is not
78 found, the new header is added first if "topnot" is true, and at the bottom
79 otherwise.
80
81 Arguments:
82 after TRUE for "after", FALSE for "before"
83 name name if adding at a specific header, else NULL
84 topnot TRUE to add at top if no header found
85 type Exim header type character (htype_something)
86 format sprintf format
87 ap va_list value for format arguments
88
89 Returns: nothing
90 */
91
92 static void
93 header_add_backend(BOOL after, uschar *name, BOOL topnot, int type,
94 const char *format, va_list ap)
95 {
96 header_line *h, *new;
97 header_line **hptr;
98
99 uschar *p, *q;
100 uschar buffer[HEADER_ADD_BUFFER_SIZE];
101
102 if (!header_last) return;
103
104 if (!string_vformat(buffer, sizeof(buffer), format, ap))
105 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "string too long in header_add: "
106 "%.100s ...", buffer);
107
108 /* Find where to insert this header */
109
110 if (!name)
111 {
112 if (after)
113 {
114 hptr = &(header_last->next);
115 h = NULL;
116 }
117 else
118 {
119 hptr = &header_list;
120
121 /* header_list->text can be NULL if we get here between when the new
122 received header is allocated and when it is actually filled in. We want
123 that header to be first, so skip it for now. */
124
125 if (!header_list->text)
126 hptr = &header_list->next;
127 h = *hptr;
128 }
129 }
130
131 else
132 {
133 int len = Ustrlen(name);
134
135 /* Find the first non-deleted header with the correct name. */
136
137 for (hptr = &header_list; (h = *hptr); hptr = &h->next)
138 if (header_testname(h, name, len, TRUE))
139 break;
140
141 /* Handle the case where no header is found. To insert at the bottom, nothing
142 needs to be done. */
143
144 if (!h)
145 {
146 if (topnot)
147 {
148 hptr = &header_list;
149 h = header_list;
150 }
151 }
152
153 /* Handle the case where a header is found. Check for more if "after" is
154 true. In this case, we want to include deleted headers in the block. */
155
156 else if (after)
157 for (;;)
158 {
159 if (!h->next || !header_testname(h, name, len, FALSE)) break;
160 hptr = &(h->next);
161 h = h->next;
162 }
163 }
164
165 /* Loop for multiple header lines, taking care about continuations. At this
166 point, we have hptr pointing to the link field that will point to the new
167 header, and h containing the following header, or NULL. */
168
169 for (p = q = buffer; *p != 0; )
170 {
171 for (;;)
172 {
173 q = Ustrchr(q, '\n');
174 if (!q) q = p + Ustrlen(p);
175 if (*(++q) != ' ' && *q != '\t') break;
176 }
177
178 new = store_get(sizeof(header_line));
179 new->text = string_copyn(p, q - p);
180 new->slen = q - p;
181 new->type = type;
182 new->next = h;
183
184 *hptr = new;
185 hptr = &(new->next);
186
187 if (!h) header_last = new;
188 p = q;
189 }
190 }
191
192
193 /*************************************************
194 * Add new header anywhere in the chain *
195 *************************************************/
196
197 /* This is an external interface to header_add_backend().
198
199 Arguments:
200 after TRUE for "after", FALSE for "before"
201 name name if adding at a specific header, else NULL
202 topnot TRUE to add at top if no header found
203 type Exim header type character (htype_something)
204 format sprintf format
205 ... format arguments
206
207 Returns: nothing
208 */
209
210 void
211 header_add_at_position(BOOL after, uschar *name, BOOL topnot, int type,
212 const char *format, ...)
213 {
214 va_list ap;
215 va_start(ap, format);
216 header_add_backend(after, name, topnot, type, format, ap);
217 va_end(ap);
218 }
219
220
221
222 /*************************************************
223 * Add new header on end of chain *
224 *************************************************/
225
226 /* This is now a convenience interface to header_add_backend().
227
228 Arguments:
229 type Exim header type character
230 format sprintf format
231 ... arguments for the format
232
233 Returns: nothing
234 */
235
236 void
237 header_add(int type, const char *format, ...)
238 {
239 va_list ap;
240 va_start(ap, format);
241 header_add_backend(TRUE, NULL, FALSE, type, format, ap);
242 va_end(ap);
243 }
244
245
246
247 /*************************************************
248 * Remove (mark as old) a header *
249 *************************************************/
250
251 /* This function is used by the filter code; it is also exported in the
252 local_scan() API. If no header is found, the function does nothing.
253
254 Arguments:
255 occ the occurrence number for multiply-defined headers
256 <= 0 means "all"; deleted headers are not counted
257 name the header name
258
259 Returns: nothing
260 */
261
262 void
263 header_remove(int occ, const uschar *name)
264 {
265 header_line *h;
266 int hcount = 0;
267 int len = Ustrlen(name);
268 for (h = header_list; h != NULL; h = h->next)
269 {
270 if (header_testname(h, name, len, TRUE) && (occ <= 0 || ++hcount == occ))
271 {
272 h->type = htype_old;
273 if (occ > 0) return;
274 }
275 }
276 }
277
278
279
280 /*************************************************
281 * Check the name of a header *
282 *************************************************/
283
284 /* This function scans a table of header field names that Exim recognizes, and
285 returns the identification of a match. If "resent" is true, the header is known
286 to start with "resent-". In that case, the function matches only those fields
287 that are allowed to appear with resent- in front of them.
288
289 Arguments:
290 h points to the header line
291 is_resent TRUE if the name starts "Resent-"
292
293 Returns: One of the htype_ enum values, identifying the header
294 */
295
296 int
297 header_checkname(header_line *h, BOOL is_resent)
298 {
299 uschar *text = h->text;
300 header_name *bot = header_names;
301 header_name *top = header_names + header_names_size;
302
303 if (is_resent) text += 7;
304
305 while (bot < top)
306 {
307 header_name *mid = bot + (top - bot)/2;
308 int c = strncmpic(text, mid->name, mid->len);
309
310 if (c == 0)
311 {
312 uschar *s = text + mid->len;
313 while (isspace(*s)) s++;
314 if (*s == ':')
315 return (!is_resent || mid->allow_resent)? mid->htype : htype_other;
316 c = 1;
317 }
318
319 if (c > 0) bot = mid + 1; else top = mid;
320 }
321
322 return htype_other;
323 }
324
325
326 /*************************************************
327 * Scan a header for certain strings *
328 *************************************************/
329
330 /* This function is used for the "personal" test. It scans a particular header
331 line for any one of a number of strings, matched caselessly either as plain
332 strings, or as regular expressions. If the header line contains a list of
333 addresses, each match is applied only to the operative part of each address in
334 the header, and non-regular expressions must be exact matches.
335
336 The patterns can be provided either as a chain of string_item structures, or
337 inline in the argument list, or both. If there is more than one header of the
338 same name, they are all searched.
339
340 Arguments:
341 name header name, including the trailing colon
342 has_addresses TRUE if the header contains a list of addresses
343 cond value to return if the header contains any of the strings
344 strings points to a chain of string_item blocks
345 count number of inline strings
346 ... the inline strings
347
348 Returns: cond if the header exists and contains one of the strings;
349 otherwise !cond
350 */
351
352
353 /* First we have a local subroutine to handle a single pattern */
354
355 static BOOL
356 one_pattern_match(uschar *name, int slen, BOOL has_addresses, uschar *pattern)
357 {
358 BOOL yield = FALSE;
359 header_line *h;
360 const pcre *re = NULL;
361
362 /* If the pattern is a regex, compile it. Bomb out if compiling fails; these
363 patterns are all constructed internally and should be valid. */
364
365 if (*pattern == '^') re = regex_must_compile(pattern, TRUE, FALSE);
366
367 /* Scan for the required header(s) and scan each one */
368
369 for (h = header_list; !yield && h != NULL; h = h->next)
370 {
371 if (h->type == htype_old || slen > h->slen ||
372 strncmpic(name, h->text, slen) != 0)
373 continue;
374
375 /* If the header is a list of addresses, extract each one in turn, and scan
376 it. A non-regex scan must be an exact match for the address. */
377
378 if (has_addresses)
379 {
380 uschar *s = h->text + slen;
381
382 while (!yield && *s != 0)
383 {
384 uschar *error, *next;
385 uschar *e = parse_find_address_end(s, FALSE);
386 int terminator = *e;
387 int start, end, domain;
388
389 /* Temporarily terminate the string at the address end while extracting
390 the operative address within. */
391
392 *e = 0;
393 next = parse_extract_address(s, &error, &start, &end, &domain, FALSE);
394 *e = terminator;
395
396 /* Move on, ready for the next address */
397
398 s = e;
399 if (*s == ',') s++;
400
401 /* If there is some kind of syntax error, just give up on this header
402 line. */
403
404 if (next == NULL) break;
405
406 /* Otherwise, test for the pattern; a non-regex must be an exact match */
407
408 yield = (re == NULL)?
409 (strcmpic(next, pattern) == 0)
410 :
411 (pcre_exec(re, NULL, CS next, Ustrlen(next), 0, PCRE_EOPT, NULL, 0)
412 >= 0);
413 }
414 }
415
416 /* For headers that are not lists of addresses, scan the entire header line,
417 and just require "contains" for non-regex patterns. */
418
419 else
420 {
421 yield = (re == NULL)?
422 (strstric(h->text, pattern, FALSE) != NULL)
423 :
424 (pcre_exec(re, NULL, CS h->text, h->slen, 0, PCRE_EOPT, NULL, 0) >= 0);
425 }
426 }
427
428 return yield;
429 }
430
431
432 /* The externally visible interface */
433
434 BOOL
435 header_match(uschar *name, BOOL has_addresses, BOOL cond, string_item *strings,
436 int count, ...)
437 {
438 va_list ap;
439 string_item *s;
440 int i;
441 int slen = Ustrlen(name);
442
443 for (s = strings; s != NULL; s = s->next)
444 {
445 if (one_pattern_match(name, slen, has_addresses, s->text)) return cond;
446 }
447
448 va_start(ap, count);
449 for (i = 0; i < count; i++)
450 if (one_pattern_match(name, slen, has_addresses, va_arg(ap, uschar *)))
451 {
452 va_end(ap);
453 return cond;
454 }
455 va_end(ap);
456
457 return !cond;
458 }
459
460 /* End of header.c */