1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
|
/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
/*! \file resconf.c */
/**
* Module for parsing resolv.conf files (largely derived from lwconfig.c).
*
* irs_resconf_load() opens the file filename and parses it to initialize
* the configuration structure.
*
* \section lwconfig_return Return Values
*
* irs_resconf_load() returns #IRS_R_SUCCESS if it successfully read and
* parsed filename. It returns a non-0 error code if filename could not be
* opened or contained incorrect resolver statements.
*
* \section lwconfig_see See Also
*
* stdio(3), \link resolver resolver \endlink
*
* \section files Files
*
* /etc/resolv.conf
*/
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/netaddr.h>
#include <isc/sockaddr.h>
#include <isc/util.h>
#include <irs/resconf.h>
#define IRS_RESCONF_MAGIC ISC_MAGIC('R', 'E', 'S', 'c')
#define IRS_RESCONF_VALID(c) ISC_MAGIC_VALID(c, IRS_RESCONF_MAGIC)
/*!
* protocol constants
*/
#if !defined(NS_INADDRSZ)
#define NS_INADDRSZ 4
#endif /* if !defined(NS_INADDRSZ) */
#if !defined(NS_IN6ADDRSZ)
#define NS_IN6ADDRSZ 16
#endif /* if !defined(NS_IN6ADDRSZ) */
/*!
* resolv.conf parameters
*/
#define RESCONFMAXNAMESERVERS 3U /*%< max 3 "nameserver" entries */
#define RESCONFMAXSEARCH 8U /*%< max 8 domains in "search" entry */
#define RESCONFMAXLINELEN 256U /*%< max size of a line */
#define RESCONFMAXSORTLIST 10U /*%< max 10 */
#define CHECK(op) \
do { \
result = (op); \
if (result != ISC_R_SUCCESS) \
goto cleanup; \
} while (0)
/*!
* configuration data structure
*/
struct irs_resconf {
/*
* The configuration data is a thread-specific object, and does not
* need to be locked.
*/
unsigned int magic;
isc_mem_t *mctx;
isc_sockaddrlist_t nameservers;
unsigned int numns; /*%< number of configured servers
* */
char *domainname;
char *search[RESCONFMAXSEARCH];
uint8_t searchnxt; /*%< index for next free slot
* */
irs_resconf_searchlist_t searchlist;
struct {
isc_netaddr_t addr;
/*% mask has a non-zero 'family' if set */
isc_netaddr_t mask;
} sortlist[RESCONFMAXSORTLIST];
uint8_t sortlistnxt;
/*%< non-zero if 'options debug' set */
uint8_t resdebug;
/*%< set to n in 'options ndots:n' */
uint8_t ndots;
/*%< set to n in 'options attempts:n' */
uint8_t attempts;
/*%< set to n in 'options timeout:n' */
uint8_t timeout;
};
static isc_result_t
resconf_parsenameserver(irs_resconf_t *conf, FILE *fp);
static isc_result_t
resconf_parsedomain(irs_resconf_t *conf, FILE *fp);
static isc_result_t
resconf_parsesearch(irs_resconf_t *conf, FILE *fp);
static isc_result_t
resconf_parsesortlist(irs_resconf_t *conf, FILE *fp);
static isc_result_t
resconf_parseoption(irs_resconf_t *ctx, FILE *fp);
/*!
* Eat characters from FP until EOL or EOF. Returns EOF or '\n'
*/
static int
eatline(FILE *fp) {
int ch;
ch = fgetc(fp);
while (ch != '\n' && ch != EOF) {
ch = fgetc(fp);
}
return (ch);
}
/*!
* Eats white space up to next newline or non-whitespace character (of
* EOF). Returns the last character read. Comments are considered white
* space.
*/
static int
eatwhite(FILE *fp) {
int ch;
ch = fgetc(fp);
while (ch != '\n' && ch != EOF && isspace((unsigned char)ch)) {
ch = fgetc(fp);
}
if (ch == ';' || ch == '#') {
ch = eatline(fp);
}
return (ch);
}
/*!
* Skip over any leading whitespace and then read in the next sequence of
* non-whitespace characters. In this context newline is not considered
* whitespace. Returns EOF on end-of-file, or the character
* that caused the reading to stop.
*/
static int
getword(FILE *fp, char *buffer, size_t size) {
char *p = NULL;
int ch;
REQUIRE(buffer != NULL);
REQUIRE(size > 0U);
p = buffer;
*p = '\0';
ch = eatwhite(fp);
if (ch == EOF) {
return (EOF);
}
do {
*p = '\0';
if (ch == EOF || isspace((unsigned char)ch)) {
break;
} else if ((size_t)(p - buffer) == size - 1) {
return (EOF); /* Not enough space. */
}
*p++ = (char)ch;
ch = fgetc(fp);
} while (1);
return (ch);
}
static isc_result_t
add_server(isc_mem_t *mctx, const char *address_str,
isc_sockaddrlist_t *nameservers) {
int error;
isc_sockaddr_t *address = NULL;
struct addrinfo hints, *res;
isc_result_t result = ISC_R_SUCCESS;
res = NULL;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = IPPROTO_UDP;
hints.ai_flags = AI_NUMERICHOST;
error = getaddrinfo(address_str, "53", &hints, &res);
if (error != 0) {
return (ISC_R_BADADDRESSFORM);
}
/* XXX: special case: treat all-0 IPv4 address as loopback */
if (res->ai_family == AF_INET) {
struct in_addr *v4;
unsigned char zeroaddress[] = { 0, 0, 0, 0 };
unsigned char loopaddress[] = { 127, 0, 0, 1 };
v4 = &((struct sockaddr_in *)res->ai_addr)->sin_addr;
if (memcmp(v4, zeroaddress, 4) == 0) {
memmove(v4, loopaddress, 4);
}
}
address = isc_mem_get(mctx, sizeof(*address));
if (res->ai_addrlen > sizeof(address->type)) {
isc_mem_put(mctx, address, sizeof(*address));
result = ISC_R_RANGE;
goto cleanup;
}
address->length = (unsigned int)res->ai_addrlen;
memmove(&address->type.ss, res->ai_addr, res->ai_addrlen);
ISC_LINK_INIT(address, link);
ISC_LIST_APPEND(*nameservers, address, link);
cleanup:
freeaddrinfo(res);
return (result);
}
static isc_result_t
create_addr(const char *buffer, isc_netaddr_t *addr, int convert_zero) {
struct in_addr v4;
struct in6_addr v6;
if (inet_pton(AF_INET, buffer, &v4) == 1) {
if (convert_zero) {
unsigned char zeroaddress[] = { 0, 0, 0, 0 };
unsigned char loopaddress[] = { 127, 0, 0, 1 };
if (memcmp(&v4, zeroaddress, 4) == 0) {
memmove(&v4, loopaddress, 4);
}
}
addr->family = AF_INET;
memmove(&addr->type.in, &v4, NS_INADDRSZ);
addr->zone = 0;
} else if (inet_pton(AF_INET6, buffer, &v6) == 1) {
addr->family = AF_INET6;
memmove(&addr->type.in6, &v6, NS_IN6ADDRSZ);
addr->zone = 0;
} else {
return (ISC_R_BADADDRESSFORM); /* Unrecognised format. */
}
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_parsenameserver(irs_resconf_t *conf, FILE *fp) {
char word[RESCONFMAXLINELEN];
int cp;
isc_result_t result;
cp = getword(fp, word, sizeof(word));
if (strlen(word) == 0U) {
return (ISC_R_UNEXPECTEDEND); /* Nothing on line. */
} else if (cp == ' ' || cp == '\t') {
cp = eatwhite(fp);
}
if (cp != EOF && cp != '\n') {
return (ISC_R_UNEXPECTEDTOKEN); /* Extra junk on line. */
}
if (conf->numns == RESCONFMAXNAMESERVERS) {
return (ISC_R_SUCCESS);
}
result = add_server(conf->mctx, word, &conf->nameservers);
if (result != ISC_R_SUCCESS) {
return (result);
}
conf->numns++;
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_parsedomain(irs_resconf_t *conf, FILE *fp) {
char word[RESCONFMAXLINELEN];
int res;
unsigned int i;
res = getword(fp, word, sizeof(word));
if (strlen(word) == 0U) {
return (ISC_R_UNEXPECTEDEND); /* Nothing else on line. */
} else if (res == ' ' || res == '\t') {
res = eatwhite(fp);
}
if (res != EOF && res != '\n') {
return (ISC_R_UNEXPECTEDTOKEN); /* Extra junk on line. */
}
if (conf->domainname != NULL) {
isc_mem_free(conf->mctx, conf->domainname);
}
/*
* Search and domain are mutually exclusive.
*/
for (i = 0; i < RESCONFMAXSEARCH; i++) {
if (conf->search[i] != NULL) {
isc_mem_free(conf->mctx, conf->search[i]);
conf->search[i] = NULL;
}
}
conf->searchnxt = 0;
conf->domainname = isc_mem_strdup(conf->mctx, word);
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_parsesearch(irs_resconf_t *conf, FILE *fp) {
int delim;
unsigned int idx;
char word[RESCONFMAXLINELEN];
if (conf->domainname != NULL) {
/*
* Search and domain are mutually exclusive.
*/
isc_mem_free(conf->mctx, conf->domainname);
conf->domainname = NULL;
}
/*
* Remove any previous search definitions.
*/
for (idx = 0; idx < RESCONFMAXSEARCH; idx++) {
if (conf->search[idx] != NULL) {
isc_mem_free(conf->mctx, conf->search[idx]);
conf->search[idx] = NULL;
}
}
conf->searchnxt = 0;
delim = getword(fp, word, sizeof(word));
if (strlen(word) == 0U) {
return (ISC_R_UNEXPECTEDEND); /* Nothing else on line. */
}
idx = 0;
while (strlen(word) > 0U) {
if (conf->searchnxt == RESCONFMAXSEARCH) {
goto ignore; /* Too many domains. */
}
INSIST(idx < sizeof(conf->search) / sizeof(conf->search[0]));
conf->search[idx] = isc_mem_strdup(conf->mctx, word);
idx++;
conf->searchnxt++;
ignore:
if (delim == EOF || delim == '\n') {
break;
} else {
delim = getword(fp, word, sizeof(word));
}
}
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_parsesortlist(irs_resconf_t *conf, FILE *fp) {
int delim, res;
unsigned int idx;
char word[RESCONFMAXLINELEN];
char *p;
delim = getword(fp, word, sizeof(word));
if (strlen(word) == 0U) {
return (ISC_R_UNEXPECTEDEND); /* Empty line after keyword. */
}
while (strlen(word) > 0U) {
if (conf->sortlistnxt == RESCONFMAXSORTLIST) {
return (ISC_R_QUOTA); /* Too many values. */
}
p = strchr(word, '/');
if (p != NULL) {
*p++ = '\0';
}
idx = conf->sortlistnxt;
INSIST(idx <
sizeof(conf->sortlist) / sizeof(conf->sortlist[0]));
res = create_addr(word, &conf->sortlist[idx].addr, 1);
if (res != ISC_R_SUCCESS) {
return (res);
}
if (p != NULL) {
res = create_addr(p, &conf->sortlist[idx].mask, 0);
if (res != ISC_R_SUCCESS) {
return (res);
}
} else {
/*
* Make up a mask. (XXX: is this correct?)
*/
conf->sortlist[idx].mask = conf->sortlist[idx].addr;
memset(&conf->sortlist[idx].mask.type, 0xff,
sizeof(conf->sortlist[idx].mask.type));
}
conf->sortlistnxt++;
if (delim == EOF || delim == '\n') {
break;
} else {
delim = getword(fp, word, sizeof(word));
}
}
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_optionnumber(const char *word, uint8_t *number) {
char *p;
long n;
n = strtol(word, &p, 10);
if (*p != '\0') { /* Bad string. */
return (ISC_R_UNEXPECTEDTOKEN);
}
if (n < 0 || n > 0xff) { /* Out of range. */
return (ISC_R_RANGE);
}
*number = n;
return (ISC_R_SUCCESS);
}
static isc_result_t
resconf_parseoption(irs_resconf_t *conf, FILE *fp) {
int delim;
isc_result_t result = ISC_R_SUCCESS;
char word[RESCONFMAXLINELEN];
delim = getword(fp, word, sizeof(word));
if (strlen(word) == 0U) {
return (ISC_R_UNEXPECTEDEND); /* Empty line after keyword. */
}
while (strlen(word) > 0U) {
if (strcmp("debug", word) == 0) {
conf->resdebug = 1;
} else if (strncmp("ndots:", word, 6) == 0) {
CHECK(resconf_optionnumber(word + 6, &conf->ndots));
} else if (strncmp("attempts:", word, 9) == 0) {
CHECK(resconf_optionnumber(word + 9, &conf->attempts));
} else if (strncmp("timeout:", word, 8) == 0) {
CHECK(resconf_optionnumber(word + 8, &conf->timeout));
}
if (delim == EOF || delim == '\n') {
break;
} else {
delim = getword(fp, word, sizeof(word));
}
}
cleanup:
return (result);
}
static isc_result_t
add_search(irs_resconf_t *conf, char *domain) {
irs_resconf_search_t *entry;
entry = isc_mem_get(conf->mctx, sizeof(*entry));
entry->domain = domain;
ISC_LINK_INIT(entry, link);
ISC_LIST_APPEND(conf->searchlist, entry, link);
return (ISC_R_SUCCESS);
}
/*% parses a file and fills in the data structure. */
isc_result_t
irs_resconf_load(isc_mem_t *mctx, const char *filename, irs_resconf_t **confp) {
FILE *fp = NULL;
char word[256];
isc_result_t rval, ret = ISC_R_SUCCESS;
irs_resconf_t *conf;
unsigned int i;
int stopchar;
REQUIRE(mctx != NULL);
REQUIRE(filename != NULL);
REQUIRE(strlen(filename) > 0U);
REQUIRE(confp != NULL && *confp == NULL);
conf = isc_mem_get(mctx, sizeof(*conf));
conf->mctx = mctx;
ISC_LIST_INIT(conf->nameservers);
ISC_LIST_INIT(conf->searchlist);
conf->numns = 0;
conf->domainname = NULL;
conf->searchnxt = 0;
conf->sortlistnxt = 0;
conf->resdebug = 0;
conf->ndots = 1;
conf->attempts = 3;
conf->timeout = 0;
for (i = 0; i < RESCONFMAXSEARCH; i++) {
conf->search[i] = NULL;
}
errno = 0;
if ((fp = fopen(filename, "r")) != NULL) {
do {
stopchar = getword(fp, word, sizeof(word));
if (stopchar == EOF) {
rval = ISC_R_SUCCESS;
POST(rval);
break;
}
if (strlen(word) == 0U) {
rval = ISC_R_SUCCESS;
} else if (strcmp(word, "nameserver") == 0) {
rval = resconf_parsenameserver(conf, fp);
} else if (strcmp(word, "domain") == 0) {
rval = resconf_parsedomain(conf, fp);
} else if (strcmp(word, "search") == 0) {
rval = resconf_parsesearch(conf, fp);
} else if (strcmp(word, "sortlist") == 0) {
rval = resconf_parsesortlist(conf, fp);
} else if (strcmp(word, "options") == 0) {
rval = resconf_parseoption(conf, fp);
} else {
/* unrecognised word. Ignore entire line */
rval = ISC_R_SUCCESS;
stopchar = eatline(fp);
if (stopchar == EOF) {
break;
}
}
if (ret == ISC_R_SUCCESS && rval != ISC_R_SUCCESS) {
ret = rval;
}
} while (1);
fclose(fp);
} else {
switch (errno) {
case ENOENT:
break;
default:
isc_mem_put(mctx, conf, sizeof(*conf));
return (ISC_R_INVALIDFILE);
}
}
if (ret != ISC_R_SUCCESS) {
goto error;
}
/*
* Construct unified search list from domain or configured
* search list
*/
if (conf->domainname != NULL) {
ret = add_search(conf, conf->domainname);
} else if (conf->searchnxt > 0) {
for (i = 0; i < conf->searchnxt; i++) {
ret = add_search(conf, conf->search[i]);
if (ret != ISC_R_SUCCESS) {
break;
}
}
}
/* If we don't find a nameserver fall back to localhost */
if (conf->numns == 0U) {
INSIST(ISC_LIST_EMPTY(conf->nameservers));
/* XXX: should we catch errors? */
(void)add_server(conf->mctx, "::1", &conf->nameservers);
(void)add_server(conf->mctx, "127.0.0.1", &conf->nameservers);
}
error:
conf->magic = IRS_RESCONF_MAGIC;
if (ret != ISC_R_SUCCESS) {
irs_resconf_destroy(&conf);
} else {
if (fp == NULL) {
ret = ISC_R_FILENOTFOUND;
}
*confp = conf;
}
return (ret);
}
void
irs_resconf_destroy(irs_resconf_t **confp) {
irs_resconf_t *conf;
isc_sockaddr_t *address;
irs_resconf_search_t *searchentry;
unsigned int i;
REQUIRE(confp != NULL);
conf = *confp;
*confp = NULL;
REQUIRE(IRS_RESCONF_VALID(conf));
while ((searchentry = ISC_LIST_HEAD(conf->searchlist)) != NULL) {
ISC_LIST_UNLINK(conf->searchlist, searchentry, link);
isc_mem_put(conf->mctx, searchentry, sizeof(*searchentry));
}
while ((address = ISC_LIST_HEAD(conf->nameservers)) != NULL) {
ISC_LIST_UNLINK(conf->nameservers, address, link);
isc_mem_put(conf->mctx, address, sizeof(*address));
}
if (conf->domainname != NULL) {
isc_mem_free(conf->mctx, conf->domainname);
}
for (i = 0; i < RESCONFMAXSEARCH; i++) {
if (conf->search[i] != NULL) {
isc_mem_free(conf->mctx, conf->search[i]);
}
}
isc_mem_put(conf->mctx, conf, sizeof(*conf));
}
isc_sockaddrlist_t *
irs_resconf_getnameservers(irs_resconf_t *conf) {
REQUIRE(IRS_RESCONF_VALID(conf));
return (&conf->nameservers);
}
irs_resconf_searchlist_t *
irs_resconf_getsearchlist(irs_resconf_t *conf) {
REQUIRE(IRS_RESCONF_VALID(conf));
return (&conf->searchlist);
}
unsigned int
irs_resconf_getndots(irs_resconf_t *conf) {
REQUIRE(IRS_RESCONF_VALID(conf));
return ((unsigned int)conf->ndots);
}
unsigned int
irs_resconf_getattempts(irs_resconf_t *conf) {
REQUIRE(IRS_RESCONF_VALID(conf));
return ((unsigned int)conf->attempts);
}
unsigned int
irs_resconf_gettimeout(irs_resconf_t *conf) {
REQUIRE(IRS_RESCONF_VALID(conf));
return ((unsigned int)conf->timeout);
}
|