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75e0e026 | 1 | /* $Cambridge: exim/test/src/fakens.c,v 1.2 2006/02/16 10:05:34 ph10 Exp $ */ |
c55a77db PH |
2 | |
3 | /************************************************* | |
4 | * fakens - A Fake Nameserver Program * | |
5 | *************************************************/ | |
6 | ||
7 | /* This program exists to support the testing of DNS handling code in Exim. It | |
8 | avoids the need to install special zones in a real nameserver. When Exim is | |
9 | running in its (new) test harness, DNS lookups are first passed to this program | |
10 | instead of to the real resolver. (With a few exceptions - see the discussion in | |
11 | the test suite's README file.) The program is also passed the name of the Exim | |
12 | spool directory; it expects to find its "zone files" in ../dnszones relative to | |
13 | that directory. Note that there is little checking in this program. The fake | |
14 | zone files are assumed to be syntactically valid. | |
15 | ||
16 | The zones that are handled are found by scanning the dnszones directory. A file | |
17 | whose name is of the form db.ip4.x is a zone file for .x.in-addr.arpa; a file | |
18 | whose name is of the form db.ip6.x is a zone file for .x.ip6.arpa; a file of | |
19 | the form db.anything.else is a zone file for .anything.else. A file of the form | |
20 | qualify.x.y specifies the domain that is used to qualify single-component | |
21 | names, except for the name "dontqualify". | |
22 | ||
23 | The arguments to the program are: | |
24 | ||
25 | the name of the Exim spool directory | |
26 | the domain name that is being sought | |
27 | the DNS record type that is being sought | |
28 | ||
29 | The output from the program is written to stdout. It is supposed to be in | |
30 | exactly the same format as a traditional namserver response (see RFC 1035) so | |
31 | that Exim can process it as normal. At present, no compression is used. | |
32 | Error messages are written to stderr. | |
33 | ||
34 | The return codes from the program are zero for success, and otherwise the | |
35 | values that are set in h_errno after a failing call to the normal resolver: | |
36 | ||
37 | 1 HOST_NOT_FOUND host not found (authoritative) | |
38 | 2 TRY_AGAIN server failure | |
39 | 3 NO_RECOVERY non-recoverable error | |
40 | 4 NO_DATA valid name, no data of requested type | |
41 | ||
42 | In a real nameserver, TRY_AGAIN is also used for a non-authoritative not found, | |
43 | but it is not used for that here. There is also one extra return code: | |
44 | ||
45 | 5 PASS_ON requests Exim to call res_search() | |
46 | ||
47 | This is used for zones that fakens does not recognize. It is also used if a | |
48 | line in the zone file contains exactly this: | |
49 | ||
50 | PASS ON NOT FOUND | |
51 | ||
52 | and the domain is not found. It converts the the result to PASS_ON instead of | |
53 | HOST_NOT_FOUND. */ | |
54 | ||
55 | #include <ctype.h> | |
56 | #include <stdarg.h> | |
57 | #include <stdio.h> | |
58 | #include <string.h> | |
59 | #include <netdb.h> | |
60 | #include <errno.h> | |
61 | #include <arpa/nameser.h> | |
62 | #include <sys/types.h> | |
63 | #include <dirent.h> | |
64 | ||
65 | #define FALSE 0 | |
66 | #define TRUE 1 | |
67 | #define PASS_ON 5 | |
68 | ||
69 | typedef int BOOL; | |
70 | typedef unsigned char uschar; | |
71 | ||
72 | #define CS (char *) | |
73 | #define CCS (const char *) | |
74 | #define US (unsigned char *) | |
75 | ||
76 | #define Ustrcat(s,t) strcat(CS(s),CCS(t)) | |
77 | #define Ustrchr(s,n) US strchr(CCS(s),n) | |
78 | #define Ustrcmp(s,t) strcmp(CCS(s),CCS(t)) | |
79 | #define Ustrcpy(s,t) strcpy(CS(s),CCS(t)) | |
80 | #define Ustrlen(s) (int)strlen(CCS(s)) | |
81 | #define Ustrncmp(s,t,n) strncmp(CCS(s),CCS(t),n) | |
82 | #define Ustrncpy(s,t,n) strncpy(CS(s),CCS(t),n) | |
83 | ||
c55a77db PH |
84 | typedef struct zoneitem { |
85 | uschar *zone; | |
86 | uschar *zonefile; | |
87 | } zoneitem; | |
88 | ||
89 | typedef struct tlist { | |
90 | uschar *name; | |
91 | int value; | |
92 | } tlist; | |
93 | ||
94 | /* On some (older?) operating systems, the standard ns_t_xxx definitions are | |
95 | not available, and only the older T_xxx ones exist in nameser.h. If ns_t_a is | |
96 | not defined, assume we are in this state. A really old system might not even | |
97 | know about AAAA and SRV at all. */ | |
98 | ||
99 | #ifndef ns_t_a | |
100 | #define ns_t_a T_A | |
101 | #define ns_t_ns T_NS | |
102 | #define ns_t_cname T_CNAME | |
103 | #define ns_t_soa T_SOA | |
104 | #define ns_t_ptr T_PTR | |
105 | #define ns_t_mx T_MX | |
106 | #define ns_t_txt T_TXT | |
107 | #define ns_t_aaaa T_AAAA | |
108 | #define ns_t_srv T_SRV | |
109 | #ifndef T_AAAA | |
110 | #define T_AAAA 28 | |
111 | #endif | |
112 | #ifndef T_SRV | |
113 | #define T_SRV 33 | |
114 | #endif | |
115 | #endif | |
116 | ||
117 | static tlist type_list[] = { | |
118 | { US"A", ns_t_a }, | |
119 | { US"NS", ns_t_ns }, | |
120 | { US"CNAME", ns_t_cname }, | |
121 | /* { US"SOA", ns_t_soa }, Not currently in use */ | |
122 | { US"PTR", ns_t_ptr }, | |
123 | { US"MX", ns_t_mx }, | |
124 | { US"TXT", ns_t_txt }, | |
125 | { US"AAAA", ns_t_aaaa }, | |
126 | { US"SRV", ns_t_srv }, | |
127 | { NULL, 0 } | |
128 | }; | |
129 | ||
130 | ||
131 | ||
132 | /************************************************* | |
133 | * Get memory and sprintf into it * | |
134 | *************************************************/ | |
135 | ||
136 | /* This is used when building a table of zones and their files. | |
137 | ||
138 | Arguments: | |
139 | format a format string | |
140 | ... arguments | |
141 | ||
142 | Returns: pointer to formatted string | |
143 | */ | |
144 | ||
145 | static uschar * | |
146 | fcopystring(uschar *format, ...) | |
147 | { | |
148 | uschar *yield; | |
149 | char buffer[256]; | |
150 | va_list ap; | |
151 | va_start(ap, format); | |
152 | vsprintf(buffer, format, ap); | |
153 | va_end(ap); | |
154 | yield = (uschar *)malloc(Ustrlen(buffer) + 1); | |
155 | Ustrcpy(yield, buffer); | |
156 | return yield; | |
157 | } | |
158 | ||
159 | ||
160 | /************************************************* | |
161 | * Pack name into memory * | |
162 | *************************************************/ | |
163 | ||
164 | /* This function packs a domain name into memory according to DNS rules. At | |
165 | present, it doesn't do any compression. | |
166 | ||
167 | Arguments: | |
168 | name the name | |
169 | pk where to put it | |
170 | ||
171 | Returns: the updated value of pk | |
172 | */ | |
173 | ||
174 | static uschar * | |
175 | packname(uschar *name, uschar *pk) | |
176 | { | |
177 | while (*name != 0) | |
178 | { | |
179 | uschar *p = name; | |
180 | while (*p != 0 && *p != '.') p++; | |
181 | *pk++ = (p - name); | |
182 | memmove(pk, name, p - name); | |
183 | pk += p - name; | |
184 | name = (*p == 0)? p : p + 1; | |
185 | } | |
186 | *pk++ = 0; | |
187 | return pk; | |
188 | } | |
189 | ||
190 | ||
191 | ||
192 | /************************************************* | |
193 | * Scan file for RRs * | |
194 | *************************************************/ | |
195 | ||
196 | /* This function scans an open "zone file" for appropriate records, and adds | |
197 | any that are found to the output buffer. | |
198 | ||
199 | Arguments: | |
200 | f the input FILE | |
201 | zone the current zone name | |
202 | domain the domain we are looking for | |
203 | qtype the type of RR we want | |
204 | qtypelen the length of qtype | |
205 | pkptr points to the output buffer pointer; this is updated | |
206 | countptr points to the record count; this is updated | |
c55a77db PH |
207 | |
208 | Returns: 0 on success, else HOST_NOT_FOUND or NO_DATA or NO_RECOVERY or | |
209 | PASS_ON - the latter if a "PASS ON NOT FOUND" line is seen | |
210 | */ | |
211 | ||
212 | static int | |
213 | find_records(FILE *f, uschar *zone, uschar *domain, uschar *qtype, | |
75e0e026 | 214 | int qtypelen, uschar **pkptr, int *countptr) |
c55a77db PH |
215 | { |
216 | int yield = HOST_NOT_FOUND; | |
c55a77db PH |
217 | int domainlen = Ustrlen(domain); |
218 | BOOL pass_on_not_found = FALSE; | |
219 | tlist *typeptr; | |
220 | uschar *pk = *pkptr; | |
221 | uschar buffer[256]; | |
222 | uschar rrdomain[256]; | |
75e0e026 | 223 | uschar RRdomain[256]; |
c55a77db PH |
224 | |
225 | /* Decode the required type */ | |
226 | ||
227 | for (typeptr = type_list; typeptr->name != NULL; typeptr++) | |
228 | { if (Ustrcmp(typeptr->name, qtype) == 0) break; } | |
229 | if (typeptr->name == NULL) | |
230 | { | |
231 | fprintf(stderr, "fakens: unknown record type %s\n", qtype); | |
232 | return NO_RECOVERY; | |
233 | } | |
234 | ||
235 | rrdomain[0] = 0; /* No previous domain */ | |
236 | (void)fseek(f, 0, SEEK_SET); /* Start again at the beginning */ | |
237 | ||
238 | /* Scan for RRs */ | |
239 | ||
240 | while (fgets(CS buffer, sizeof(buffer), f) != NULL) | |
241 | { | |
242 | uschar *rdlptr; | |
243 | uschar *p, *ep, *pp; | |
244 | BOOL found_cname = FALSE; | |
245 | int i, plen, value; | |
246 | int tvalue = typeptr->value; | |
247 | int qtlen = qtypelen; | |
248 | ||
249 | p = buffer; | |
250 | while (isspace(*p)) p++; | |
251 | if (*p == 0 || *p == ';') continue; | |
252 | ||
253 | if (Ustrncmp(p, "PASS ON NOT FOUND", 17) == 0) | |
254 | { | |
255 | pass_on_not_found = TRUE; | |
256 | continue; | |
257 | } | |
258 | ||
259 | ep = buffer + Ustrlen(buffer); | |
260 | while (isspace(ep[-1])) ep--; | |
261 | *ep = 0; | |
262 | ||
263 | p = buffer; | |
264 | if (!isspace(*p)) | |
265 | { | |
266 | uschar *pp = rrdomain; | |
75e0e026 PH |
267 | uschar *PP = RRdomain; |
268 | while (!isspace(*p)) | |
269 | { | |
270 | *pp++ = tolower(*p); | |
271 | *PP++ = *p++; | |
272 | } | |
273 | if (pp[-1] != '.') | |
274 | { | |
275 | Ustrcpy(pp, zone); | |
276 | Ustrcpy(PP, zone); | |
277 | } | |
278 | else | |
279 | { | |
280 | pp[-1] = 0; | |
281 | PP[-1] = 0; | |
282 | } | |
c55a77db PH |
283 | } |
284 | ||
285 | /* Compare domain names; first check for a wildcard */ | |
286 | ||
287 | if (rrdomain[0] == '*') | |
288 | { | |
289 | int restlen = Ustrlen(rrdomain) - 1; | |
290 | if (domainlen > restlen && | |
291 | Ustrcmp(domain + domainlen - restlen, rrdomain + 1) != 0) continue; | |
292 | } | |
293 | ||
294 | /* Not a wildcard RR */ | |
295 | ||
296 | else if (Ustrcmp(domain, rrdomain) != 0) continue; | |
297 | ||
298 | /* The domain matches */ | |
299 | ||
300 | if (yield == HOST_NOT_FOUND) yield = NO_DATA; | |
301 | ||
302 | /* Compare RR types; a CNAME record is always returned */ | |
303 | ||
304 | while (isspace(*p)) p++; | |
305 | ||
306 | if (Ustrncmp(p, "CNAME", 5) == 0) | |
307 | { | |
308 | tvalue = ns_t_cname; | |
309 | qtlen = 5; | |
310 | found_cname = TRUE; | |
311 | } | |
312 | else if (Ustrncmp(p, qtype, qtypelen) != 0 || !isspace(p[qtypelen])) continue; | |
313 | ||
314 | /* Found a relevant record */ | |
315 | ||
316 | yield = 0; | |
317 | *countptr = *countptr + 1; | |
318 | ||
319 | p += qtlen; | |
320 | while (isspace(*p)) p++; | |
321 | ||
75e0e026 PH |
322 | /* For a wildcard record, use the search name; otherwise use the record's |
323 | name in its original case because it might contain upper case letters. */ | |
324 | ||
325 | pk = packname((rrdomain[0] == '*')? domain : RRdomain, pk); | |
c55a77db PH |
326 | *pk++ = (tvalue >> 8) & 255; |
327 | *pk++ = (tvalue) & 255; | |
328 | *pk++ = 0; | |
329 | *pk++ = 1; /* class = IN */ | |
330 | ||
331 | pk += 4; /* TTL field; don't care */ | |
332 | ||
333 | rdlptr = pk; /* remember rdlength field */ | |
334 | pk += 2; | |
335 | ||
336 | /* The rest of the data depends on the type */ | |
337 | ||
338 | switch (tvalue) | |
339 | { | |
340 | case ns_t_soa: /* Not currently used */ | |
341 | break; | |
342 | ||
343 | case ns_t_a: | |
344 | for (i = 0; i < 4; i++) | |
345 | { | |
346 | value = 0; | |
347 | while (isdigit(*p)) value = value*10 + *p++ - '0'; | |
348 | *pk++ = value; | |
349 | p++; | |
350 | } | |
351 | break; | |
352 | ||
353 | /* The only occurrence of a double colon is for ::1 */ | |
354 | case ns_t_aaaa: | |
355 | if (Ustrcmp(p, "::1") == 0) | |
356 | { | |
357 | memset(pk, 0, 15); | |
358 | pk += 15; | |
359 | *pk++ = 1; | |
360 | } | |
361 | else for (i = 0; i < 8; i++) | |
362 | { | |
363 | value = 0; | |
364 | while (isxdigit(*p)) | |
365 | { | |
366 | value = value * 16 + toupper(*p) - (isdigit(*p)? '0' : '7'); | |
367 | p++; | |
368 | } | |
369 | *pk++ = (value >> 8) & 255; | |
370 | *pk++ = value & 255; | |
371 | p++; | |
372 | } | |
373 | break; | |
374 | ||
375 | case ns_t_mx: | |
376 | value = 0; | |
377 | while (isdigit(*p)) value = value*10 + *p++ - '0'; | |
378 | while (isspace(*p)) p++; | |
379 | *pk++ = (value >> 8) & 255; | |
380 | *pk++ = value & 255; | |
75e0e026 PH |
381 | if (ep[-1] != '.') sprintf(ep, "%s.", zone); |
382 | pk = packname(p, pk); | |
383 | plen = Ustrlen(p); | |
384 | break; | |
c55a77db PH |
385 | |
386 | case ns_t_txt: | |
387 | pp = pk++; | |
388 | if (*p == '"') p++; /* Should always be the case */ | |
389 | while (*p != 0 && *p != '"') *pk++ = *p++; | |
390 | *pp = pk - pp - 1; | |
391 | break; | |
392 | ||
393 | case ns_t_srv: | |
394 | for (i = 0; i < 3; i++) | |
395 | { | |
396 | value = 0; | |
397 | while (isdigit(*p)) value = value*10 + *p++ - '0'; | |
398 | while (isspace(*p)) p++; | |
399 | *pk++ = (value >> 8) & 255; | |
400 | *pk++ = value & 255; | |
401 | } | |
402 | ||
403 | /* Fall through */ | |
404 | ||
405 | case ns_t_cname: | |
406 | case ns_t_ns: | |
407 | case ns_t_ptr: | |
c55a77db PH |
408 | if (ep[-1] != '.') sprintf(ep, "%s.", zone); |
409 | pk = packname(p, pk); | |
410 | plen = Ustrlen(p); | |
c55a77db PH |
411 | break; |
412 | } | |
413 | ||
414 | /* Fill in the length, and we are done with this RR */ | |
415 | ||
416 | rdlptr[0] = ((pk - rdlptr - 2) >> 8) & 255; | |
417 | rdlptr[1] = (pk -rdlptr - 2) & 255; | |
418 | ||
419 | /* If we have just yielded a CNAME, we must change the domain name to the | |
420 | new domain, and re-start the scan from the beginning. */ | |
421 | ||
422 | if (found_cname) | |
423 | { | |
424 | domain = fcopystring("%s", p); | |
425 | domainlen = Ustrlen(domain); | |
426 | domain[domainlen - 1] = 0; /* Removed trailing dot */ | |
427 | rrdomain[0] = 0; /* No previous domain */ | |
428 | (void)fseek(f, 0, SEEK_SET); /* Start again at the beginning */ | |
429 | } | |
430 | } | |
431 | ||
432 | *pkptr = pk; | |
433 | return (yield == HOST_NOT_FOUND && pass_on_not_found)? PASS_ON : yield; | |
434 | } | |
435 | ||
436 | ||
437 | ||
438 | /************************************************* | |
439 | * Entry point and main program * | |
440 | *************************************************/ | |
441 | ||
442 | int | |
443 | main(int argc, char **argv) | |
444 | { | |
445 | FILE *f; | |
446 | DIR *d; | |
75e0e026 | 447 | int domlen, qtypelen; |
c55a77db PH |
448 | int yield, count; |
449 | int i; | |
450 | int zonecount = 0; | |
c55a77db | 451 | struct dirent *de; |
c55a77db PH |
452 | zoneitem zones[32]; |
453 | uschar *qualify = NULL; | |
454 | uschar *p, *zone; | |
455 | uschar *zonefile = NULL; | |
456 | uschar domain[256]; | |
457 | uschar buffer[256]; | |
458 | uschar qtype[12]; | |
459 | uschar packet[512]; | |
460 | uschar *pk = packet; | |
461 | ||
462 | if (argc != 4) | |
463 | { | |
464 | fprintf(stderr, "fakens: expected 3 arguments, received %d\n", argc-1); | |
465 | return NO_RECOVERY; | |
466 | } | |
467 | ||
468 | /* Find the zones */ | |
469 | ||
470 | (void)sprintf(buffer, "%s/../dnszones", argv[1]); | |
471 | ||
472 | d = opendir(CCS buffer); | |
473 | if (d == NULL) | |
474 | { | |
475 | fprintf(stderr, "fakens: failed to opendir %s: %s\n", buffer, | |
476 | strerror(errno)); | |
477 | return NO_RECOVERY; | |
478 | } | |
479 | ||
480 | while ((de = readdir(d)) != NULL) | |
481 | { | |
482 | uschar *name = de->d_name; | |
483 | if (Ustrncmp(name, "qualify.", 8) == 0) | |
484 | { | |
485 | qualify = fcopystring("%s", name + 7); | |
486 | continue; | |
487 | } | |
488 | if (Ustrncmp(name, "db.", 3) != 0) continue; | |
489 | if (Ustrncmp(name + 3, "ip4.", 4) == 0) | |
490 | zones[zonecount].zone = fcopystring("%s.in-addr.arpa", name + 6); | |
491 | else if (Ustrncmp(name + 3, "ip6.", 4) == 0) | |
492 | zones[zonecount].zone = fcopystring("%s.ip6.arpa", name + 6); | |
493 | else | |
494 | zones[zonecount].zone = fcopystring("%s", name + 2); | |
495 | zones[zonecount++].zonefile = fcopystring("%s", name); | |
496 | } | |
497 | (void)closedir(d); | |
498 | ||
499 | /* Get the RR type and upper case it, and check that we recognize it. */ | |
500 | ||
501 | Ustrncpy(qtype, argv[3], sizeof(qtype)); | |
502 | qtypelen = Ustrlen(qtype); | |
503 | for (p = qtype; *p != 0; p++) *p = toupper(*p); | |
504 | ||
505 | /* Find the domain, lower case it, check that it is in a zone that we handle, | |
506 | and set up the zone file name. The zone names in the table all start with a | |
507 | dot. */ | |
508 | ||
509 | domlen = Ustrlen(argv[2]); | |
510 | if (argv[2][domlen-1] == '.') domlen--; | |
511 | Ustrncpy(domain, argv[2], domlen); | |
512 | domain[domlen] = 0; | |
513 | for (i = 0; i < domlen; i++) domain[i] = tolower(domain[i]); | |
514 | ||
515 | if (Ustrchr(domain, '.') == NULL && qualify != NULL && | |
516 | Ustrcmp(domain, "dontqualify") != 0) | |
517 | { | |
518 | Ustrcat(domain, qualify); | |
519 | domlen += Ustrlen(qualify); | |
520 | } | |
521 | ||
522 | for (i = 0; i < zonecount; i++) | |
523 | { | |
524 | int zlen; | |
525 | zone = zones[i].zone; | |
526 | zlen = Ustrlen(zone); | |
527 | if (Ustrcmp(domain, zone+1) == 0 || (domlen >= zlen && | |
528 | Ustrcmp(domain + domlen - zlen, zone) == 0)) | |
529 | { | |
530 | zonefile = zones[i].zonefile; | |
531 | break; | |
532 | } | |
533 | } | |
534 | ||
535 | if (zonefile == NULL) | |
536 | { | |
537 | fprintf(stderr, "fakens: query not in faked zone: domain is: %s\n", domain); | |
538 | return PASS_ON; | |
539 | } | |
540 | ||
541 | (void)sprintf(buffer, "%s/../dnszones/%s", argv[1], zonefile); | |
542 | ||
543 | /* Initialize the start of the response packet. We don't have to fake up | |
544 | everything, because we know that Exim will look only at the answer and | |
545 | additional section parts. */ | |
546 | ||
547 | memset(packet, 0, 12); | |
548 | pk += 12; | |
549 | ||
550 | /* Open the zone file. */ | |
551 | ||
552 | f = fopen(buffer, "r"); | |
553 | if (f == NULL) | |
554 | { | |
555 | fprintf(stderr, "fakens: failed to open %s: %s\n", buffer, strerror(errno)); | |
556 | return NO_RECOVERY; | |
557 | } | |
558 | ||
559 | /* Find the records we want, and add them to the result. */ | |
560 | ||
561 | count = 0; | |
75e0e026 | 562 | yield = find_records(f, zone, domain, qtype, qtypelen, &pk, &count); |
c55a77db PH |
563 | if (yield == NO_RECOVERY) goto END_OFF; |
564 | ||
565 | packet[6] = (count >> 8) & 255; | |
566 | packet[7] = count & 255; | |
567 | ||
75e0e026 PH |
568 | /* There is no need to return any additional records because Exim no longer |
569 | (from release 4.61) makes any use of them. */ | |
c55a77db | 570 | |
75e0e026 PH |
571 | packet[10] = 0; |
572 | packet[11] = 0; | |
c55a77db PH |
573 | |
574 | /* Close the zone file, write the result, and return. */ | |
575 | ||
576 | END_OFF: | |
577 | (void)fclose(f); | |
578 | (void)fwrite(packet, 1, pk - packet, stdout); | |
579 | return yield; | |
580 | } | |
581 | ||
582 | /* End of fakens.c */ |