1 /* $NetBSD: dns_nw.c,v 1.1.1.2 2012/09/09 16:07:52 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #if defined(LIBC_SCCS) && !defined(lint)
21 static const char rcsid[] = "Id: dns_nw.c,v 1.12 2005/04/27 04:56:22 sra Exp ";
22 #endif /* LIBC_SCCS and not lint */
23
24 /* Imports. */
25
26 #include "port_before.h"
27
28 #include <sys/param.h>
29 #include <sys/socket.h>
30
31 #include <netinet/in.h>
32 #include <arpa/inet.h>
33 #include <arpa/nameser.h>
34
35 #include <ctype.h>
36 #include <errno.h>
37 #include <netdb.h>
38 #include <resolv.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42
43 #include <isc/memcluster.h>
44 #include <irs.h>
45
46 #include "port_after.h"
47
48 #include "irs_p.h"
49 #include "dns_p.h"
50
51 #ifdef SPRINTF_CHAR
52 # define SPRINTF(x) strlen(sprintf/**/x)
53 #else
54 # define SPRINTF(x) sprintf x
55 #endif
56
57 /* Definitions. */
58
59 #define MAXALIASES 35
60
61 #define MAXPACKET (64*1024)
62
63 struct pvt {
64 struct nwent net;
65 char * ali[MAXALIASES];
66 char buf[BUFSIZ+1];
67 struct __res_state * res;
68 void (*free_res)(void *);
69 };
70
71 typedef union {
72 long al;
73 char ac;
74 } align;
75
76 enum by_what { by_addr, by_name };
77
78 /* Forwards. */
79
80 static void nw_close(struct irs_nw *);
81 static struct nwent * nw_byname(struct irs_nw *, const char *, int);
82 static struct nwent * nw_byaddr(struct irs_nw *, void *, int, int);
83 static struct nwent * nw_next(struct irs_nw *);
84 static void nw_rewind(struct irs_nw *);
85 static void nw_minimize(struct irs_nw *);
86 static struct __res_state * nw_res_get(struct irs_nw *this);
87 static void nw_res_set(struct irs_nw *this,
88 struct __res_state *res,
89 void (*free_res)(void *));
90
91 static struct nwent * get1101byaddr(struct irs_nw *, u_char *, int);
92 static struct nwent * get1101byname(struct irs_nw *, const char *);
93 static struct nwent * get1101answer(struct irs_nw *,
94 u_char *ansbuf, int anslen,
95 enum by_what by_what,
96 int af, const char *name,
97 const u_char *addr, int addrlen);
98 static struct nwent * get1101mask(struct irs_nw *this, struct nwent *);
99 static int make1101inaddr(const u_char *, int, char *, int);
100 static void normalize_name(char *name);
101 static int init(struct irs_nw *this);
102
103 /* Exports. */
104
105 struct irs_nw *
irs_dns_nw(struct irs_acc * this)106 irs_dns_nw(struct irs_acc *this) {
107 struct irs_nw *nw;
108 struct pvt *pvt;
109
110 UNUSED(this);
111
112 if (!(pvt = memget(sizeof *pvt))) {
113 errno = ENOMEM;
114 return (NULL);
115 }
116 memset(pvt, 0, sizeof *pvt);
117 if (!(nw = memget(sizeof *nw))) {
118 memput(pvt, sizeof *pvt);
119 errno = ENOMEM;
120 return (NULL);
121 }
122 memset(nw, 0x5e, sizeof *nw);
123 nw->private = pvt;
124 nw->close = nw_close;
125 nw->byname = nw_byname;
126 nw->byaddr = nw_byaddr;
127 nw->next = nw_next;
128 nw->rewind = nw_rewind;
129 nw->minimize = nw_minimize;
130 nw->res_get = nw_res_get;
131 nw->res_set = nw_res_set;
132 return (nw);
133 }
134
135 /* Methods. */
136
137 static void
nw_close(struct irs_nw * this)138 nw_close(struct irs_nw *this) {
139 struct pvt *pvt = (struct pvt *)this->private;
140
141 nw_minimize(this);
142
143 if (pvt->res && pvt->free_res)
144 (*pvt->free_res)(pvt->res);
145
146 memput(pvt, sizeof *pvt);
147 memput(this, sizeof *this);
148 }
149
150 static struct nwent *
nw_byname(struct irs_nw * this,const char * name,int af)151 nw_byname(struct irs_nw *this, const char *name, int af) {
152 struct pvt *pvt = (struct pvt *)this->private;
153
154 if (init(this) == -1)
155 return (NULL);
156
157 switch (af) {
158 case AF_INET:
159 return (get1101byname(this, name));
160 default:
161 (void)NULL;
162 }
163 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
164 errno = EAFNOSUPPORT;
165 return (NULL);
166 }
167
168 static struct nwent *
nw_byaddr(struct irs_nw * this,void * net,int len,int af)169 nw_byaddr(struct irs_nw *this, void *net, int len, int af) {
170 struct pvt *pvt = (struct pvt *)this->private;
171
172 if (init(this) == -1)
173 return (NULL);
174
175 switch (af) {
176 case AF_INET:
177 return (get1101byaddr(this, net, len));
178 default:
179 (void)NULL;
180 }
181 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
182 errno = EAFNOSUPPORT;
183 return (NULL);
184 }
185
186 static struct nwent *
nw_next(struct irs_nw * this)187 nw_next(struct irs_nw *this) {
188
189 UNUSED(this);
190
191 return (NULL);
192 }
193
194 static void
nw_rewind(struct irs_nw * this)195 nw_rewind(struct irs_nw *this) {
196 UNUSED(this);
197 /* NOOP */
198 }
199
200 static void
nw_minimize(struct irs_nw * this)201 nw_minimize(struct irs_nw *this) {
202 struct pvt *pvt = (struct pvt *)this->private;
203
204 if (pvt->res)
205 res_nclose(pvt->res);
206 }
207
208 static struct __res_state *
nw_res_get(struct irs_nw * this)209 nw_res_get(struct irs_nw *this) {
210 struct pvt *pvt = (struct pvt *)this->private;
211
212 if (!pvt->res) {
213 struct __res_state *res;
214 res = (struct __res_state *)malloc(sizeof *res);
215 if (!res) {
216 errno = ENOMEM;
217 return (NULL);
218 }
219 memset(res, 0, sizeof *res);
220 nw_res_set(this, res, free);
221 }
222
223 return (pvt->res);
224 }
225
226 static void
nw_res_set(struct irs_nw * this,struct __res_state * res,void (* free_res)(void *))227 nw_res_set(struct irs_nw *this, struct __res_state *res,
228 void (*free_res)(void *)) {
229 struct pvt *pvt = (struct pvt *)this->private;
230
231 if (pvt->res && pvt->free_res) {
232 res_nclose(pvt->res);
233 (*pvt->free_res)(pvt->res);
234 }
235
236 pvt->res = res;
237 pvt->free_res = free_res;
238 }
239
240 /* Private. */
241
242 static struct nwent *
get1101byname(struct irs_nw * this,const char * name)243 get1101byname(struct irs_nw *this, const char *name) {
244 struct pvt *pvt = (struct pvt *)this->private;
245 u_char *ansbuf;
246 int anslen;
247 struct nwent *result;
248
249 ansbuf = memget(MAXPACKET);
250 if (ansbuf == NULL) {
251 errno = ENOMEM;
252 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
253 return (NULL);
254 }
255 anslen = res_nsearch(pvt->res, name, C_IN, T_PTR, ansbuf, MAXPACKET);
256 if (anslen < 0) {
257 memput(ansbuf, MAXPACKET);
258 return (NULL);
259 }
260 result = get1101mask(this, get1101answer(this, ansbuf, anslen, by_name,
261 AF_INET, name, NULL, 0));
262 memput(ansbuf, MAXPACKET);
263 return (result);
264 }
265
266 static struct nwent *
get1101byaddr(struct irs_nw * this,u_char * net,int len)267 get1101byaddr(struct irs_nw *this, u_char *net, int len) {
268 struct pvt *pvt = (struct pvt *)this->private;
269 char qbuf[sizeof "255.255.255.255.in-addr.arpa"];
270 struct nwent *result;
271 u_char *ansbuf;
272 int anslen;
273
274 if (len < 1 || len > 32) {
275 errno = EINVAL;
276 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
277 return (NULL);
278 }
279 if (make1101inaddr(net, len, qbuf, sizeof qbuf) < 0)
280 return (NULL);
281 ansbuf = memget(MAXPACKET);
282 if (ansbuf == NULL) {
283 errno = ENOMEM;
284 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
285 return (NULL);
286 }
287 anslen = res_nquery(pvt->res, qbuf, C_IN, T_PTR, ansbuf, MAXPACKET);
288 if (anslen < 0) {
289 memput(ansbuf, MAXPACKET);
290 return (NULL);
291 }
292 result = get1101mask(this, get1101answer(this, ansbuf, anslen, by_addr,
293 AF_INET, NULL, net, len));
294 memput(ansbuf, MAXPACKET);
295 return (result);
296 }
297
298 static struct nwent *
get1101answer(struct irs_nw * this,u_char * ansbuf,int anslen,enum by_what by_what,int af,const char * name,const u_char * addr,int addrlen)299 get1101answer(struct irs_nw *this,
300 u_char *ansbuf, int anslen, enum by_what by_what,
301 int af, const char *name, const u_char *addr, int addrlen)
302 {
303 struct pvt *pvt = (struct pvt *)this->private;
304 int type, class, ancount, qdcount, haveanswer;
305 char *bp, *ep, **ap;
306 u_char *cp, *eom;
307 HEADER *hp;
308
309 /* Initialize, and parse header. */
310 eom = ansbuf + anslen;
311 if (ansbuf + HFIXEDSZ > eom) {
312 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
313 return (NULL);
314 }
315 hp = (HEADER *)ansbuf;
316 cp = ansbuf + HFIXEDSZ;
317 qdcount = ntohs(hp->qdcount);
318 while (qdcount-- > 0) {
319 int n = dn_skipname(cp, eom);
320 cp += n + QFIXEDSZ;
321 if (n < 0 || cp > eom) {
322 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
323 return (NULL);
324 }
325 }
326 ancount = ntohs(hp->ancount);
327 if (!ancount) {
328 if (hp->aa)
329 RES_SET_H_ERRNO(pvt->res, HOST_NOT_FOUND);
330 else
331 RES_SET_H_ERRNO(pvt->res, TRY_AGAIN);
332 return (NULL);
333 }
334
335 /* Prepare a return structure. */
336 bp = pvt->buf;
337 ep = pvt->buf + sizeof(pvt->buf);
338 pvt->net.n_name = NULL;
339 pvt->net.n_aliases = pvt->ali;
340 pvt->net.n_addrtype = af;
341 pvt->net.n_addr = NULL;
342 pvt->net.n_length = addrlen;
343
344 /* Save input key if given. */
345 switch (by_what) {
346 case by_name:
347 if (name != NULL) {
348 int n = strlen(name) + 1;
349
350 if (n > (ep - bp)) {
351 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
352 return (NULL);
353 }
354 pvt->net.n_name = strcpy(bp, name); /* (checked) */
355 bp += n;
356 }
357 break;
358 case by_addr:
359 if (addr != NULL && addrlen != 0) {
360 int n = addrlen / 8 + ((addrlen % 8) != 0);
361
362 if (INADDRSZ > (ep - bp)) {
363 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
364 return (NULL);
365 }
366 memset(bp, 0, INADDRSZ);
367 memcpy(bp, addr, n);
368 pvt->net.n_addr = bp;
369 bp += INADDRSZ;
370 }
371 break;
372 default:
373 abort();
374 }
375
376 /* Parse the answer, collect aliases. */
377 ap = pvt->ali;
378 haveanswer = 0;
379 while (--ancount >= 0 && cp < eom) {
380 int n = dn_expand(ansbuf, eom, cp, bp, ep - bp);
381
382 cp += n; /*%< Owner */
383 if (n < 0 || !maybe_dnok(pvt->res, bp) ||
384 cp + 3 * INT16SZ + INT32SZ > eom) {
385 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
386 return (NULL);
387 }
388 GETSHORT(type, cp); /*%< Type */
389 GETSHORT(class, cp); /*%< Class */
390 cp += INT32SZ; /*%< TTL */
391 GETSHORT(n, cp); /*%< RDLENGTH */
392 if (class == C_IN && type == T_PTR) {
393 int nn;
394
395 nn = dn_expand(ansbuf, eom, cp, bp, ep - bp);
396 if (nn < 0 || !maybe_hnok(pvt->res, bp) || nn != n) {
397 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
398 return (NULL);
399 }
400 normalize_name(bp);
401 switch (by_what) {
402 case by_addr: {
403 if (pvt->net.n_name == NULL)
404 pvt->net.n_name = bp;
405 else if (ns_samename(pvt->net.n_name, bp) == 1)
406 break;
407 else
408 *ap++ = bp;
409 nn = strlen(bp) + 1;
410 bp += nn;
411 haveanswer++;
412 break;
413 }
414 case by_name: {
415 u_int b1, b2, b3, b4;
416
417 if (pvt->net.n_addr != NULL ||
418 sscanf(bp, "%u.%u.%u.%u.in-addr.arpa",
419 &b1, &b2, &b3, &b4) != 4)
420 break;
421 if ((ep - bp) < INADDRSZ) {
422 RES_SET_H_ERRNO(pvt->res, NO_RECOVERY);
423 return (NULL);
424 }
425 pvt->net.n_addr = bp;
426 *bp++ = b4;
427 *bp++ = b3;
428 *bp++ = b2;
429 *bp++ = b1;
430 pvt->net.n_length = INADDRSZ * 8;
431 haveanswer++;
432 }
433 }
434 }
435 cp += n; /*%< RDATA */
436 }
437 if (!haveanswer) {
438 RES_SET_H_ERRNO(pvt->res, TRY_AGAIN);
439 return (NULL);
440 }
441 *ap = NULL;
442
443 return (&pvt->net);
444 }
445
446 static struct nwent *
get1101mask(struct irs_nw * this,struct nwent * nwent)447 get1101mask(struct irs_nw *this, struct nwent *nwent) {
448 struct pvt *pvt = (struct pvt *)this->private;
449 char qbuf[sizeof "255.255.255.255.in-addr.arpa"], owner[MAXDNAME];
450 int anslen, type, class, ancount, qdcount;
451 u_char *ansbuf, *cp, *eom;
452 HEADER *hp;
453
454 if (!nwent)
455 return (NULL);
456 if (make1101inaddr(nwent->n_addr, nwent->n_length, qbuf, sizeof qbuf)
457 < 0) {
458 /* "First, do no harm." */
459 return (nwent);
460 }
461
462 ansbuf = memget(MAXPACKET);
463 if (ansbuf == NULL) {
464 errno = ENOMEM;
465 RES_SET_H_ERRNO(pvt->res, NETDB_INTERNAL);
466 return (NULL);
467 }
468 /* Query for the A RR that would hold this network's mask. */
469 anslen = res_nquery(pvt->res, qbuf, C_IN, T_A, ansbuf, MAXPACKET);
470 if (anslen < HFIXEDSZ) {
471 memput(ansbuf, MAXPACKET);
472 return (nwent);
473 }
474
475 /* Initialize, and parse header. */
476 hp = (HEADER *)ansbuf;
477 cp = ansbuf + HFIXEDSZ;
478 eom = ansbuf + anslen;
479 qdcount = ntohs(hp->qdcount);
480 while (qdcount-- > 0) {
481 int n = dn_skipname(cp, eom);
482 cp += n + QFIXEDSZ;
483 if (n < 0 || cp > eom) {
484 memput(ansbuf, MAXPACKET);
485 return (nwent);
486 }
487 }
488 ancount = ntohs(hp->ancount);
489
490 /* Parse the answer, collect aliases. */
491 while (--ancount >= 0 && cp < eom) {
492 int n = dn_expand(ansbuf, eom, cp, owner, sizeof owner);
493
494 if (n < 0 || !maybe_dnok(pvt->res, owner))
495 break;
496 cp += n; /*%< Owner */
497 if (cp + 3 * INT16SZ + INT32SZ > eom)
498 break;
499 GETSHORT(type, cp); /*%< Type */
500 GETSHORT(class, cp); /*%< Class */
501 cp += INT32SZ; /*%< TTL */
502 GETSHORT(n, cp); /*%< RDLENGTH */
503 if (cp + n > eom)
504 break;
505 if (n == INADDRSZ && class == C_IN && type == T_A &&
506 ns_samename(qbuf, owner) == 1) {
507 /* This A RR indicates the actual netmask. */
508 int nn, mm;
509
510 nwent->n_length = 0;
511 for (nn = 0; nn < INADDRSZ; nn++)
512 for (mm = 7; mm >= 0; mm--)
513 if (cp[nn] & (1 << mm))
514 nwent->n_length++;
515 else
516 break;
517 }
518 cp += n; /*%< RDATA */
519 }
520 memput(ansbuf, MAXPACKET);
521 return (nwent);
522 }
523
524 static int
make1101inaddr(const u_char * net,int bits,char * name,int size)525 make1101inaddr(const u_char *net, int bits, char *name, int size) {
526 int n, m;
527 char *ep;
528
529 ep = name + size;
530
531 /* Zero fill any whole bytes left out of the prefix. */
532 for (n = (32 - bits) / 8; n > 0; n--) {
533 if (ep - name < (int)(sizeof "0."))
534 goto emsgsize;
535 m = SPRINTF((name, "0."));
536 name += m;
537 }
538
539 /* Format the partial byte, if any, within the prefix. */
540 if ((n = bits % 8) != 0) {
541 if (ep - name < (int)(sizeof "255."))
542 goto emsgsize;
543 m = SPRINTF((name, "%u.",
544 net[bits / 8] & ~((1 << (8 - n)) - 1)));
545 name += m;
546 }
547
548 /* Format the whole bytes within the prefix. */
549 for (n = bits / 8; n > 0; n--) {
550 if (ep - name < (int)(sizeof "255."))
551 goto emsgsize;
552 m = SPRINTF((name, "%u.", net[n - 1]));
553 name += m;
554 }
555
556 /* Add the static text. */
557 if (ep - name < (int)(sizeof "in-addr.arpa"))
558 goto emsgsize;
559 (void) SPRINTF((name, "in-addr.arpa"));
560 return (0);
561
562 emsgsize:
563 errno = EMSGSIZE;
564 return (-1);
565 }
566
567 static void
normalize_name(char * name)568 normalize_name(char *name) {
569 char *t;
570
571 /* Make lower case. */
572 for (t = name; *t; t++)
573 if (isascii((unsigned char)*t) && isupper((unsigned char)*t))
574 *t = tolower((*t)&0xff);
575
576 /* Remove trailing dots. */
577 while (t > name && t[-1] == '.')
578 *--t = '\0';
579 }
580
581 static int
init(struct irs_nw * this)582 init(struct irs_nw *this) {
583 struct pvt *pvt = (struct pvt *)this->private;
584
585 if (!pvt->res && !nw_res_get(this))
586 return (-1);
587 if (((pvt->res->options & RES_INIT) == 0U) &&
588 res_ninit(pvt->res) == -1)
589 return (-1);
590 return (0);
591 }
592
593 /*! \file */
594