about summary refs log tree commit diff
path: root/resolv/nss_dns/dns-host.c
blob: f8345bb5912176dbb0636472ccd7ea1236f5d52e (plain) (blame)
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
/* Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* Parts of this file are plain copies of the file `gethtnamadr.c' from
   the bind package and it has the following copyright.  */

/*
 * ++Copyright++ 1985, 1988, 1993
 * -
 * Copyright (c) 1985, 1988, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <sys/syslog.h>

#include "nsswitch.h"

/* Get implementation for some internal functions.  */
#include <resolv/mapv4v6addr.h>
#include <resolv/mapv4v6hostent.h>

/* Maximum number of aliases we allow.  */
#define MAX_NR_ALIASES	48
#define MAX_NR_ADDRS	48

#if PACKETSZ > 1024
# define MAXPACKET	PACKETSZ
#else
# define MAXPACKET	1024
#endif
/* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length.  */
#ifdef MAXHOSTNAMELEN
# undef MAXHOSTNAMELEN
#endif
#define MAXHOSTNAMELEN 256

static const char AskedForGot[] = "\
gethostby*.getanswer: asked for \"%s\", got \"%s\"";


/* We need this time later.  */
typedef union querybuf
{
  HEADER hdr;
  u_char buf[MAXPACKET];
} querybuf;


static enum nss_status getanswer_r (const querybuf *answer, int anslen,
				    const char *qname, int qtype,
				    struct hostent *result, char *buffer,
				    size_t buflen, int *h_errnop);

enum nss_status
_nss_dns_gethostbyname2_r (const char *name, int af, struct hostent *result,
			   char *buffer, size_t buflen, int *h_errnop)
{
  querybuf host_buffer;
  int size, type, n;
  const char *cp;

  switch (af) {
  case AF_INET:
    size = INADDRSZ;
    type = T_A;
    break;
  case AF_INET6:
    size = IN6ADDRSZ;
    type = T_AAAA;
    break;
  default:
    *h_errnop = NETDB_INTERNAL;
    __set_errno (EAFNOSUPPORT);
    return NSS_STATUS_UNAVAIL;
  }

  result->h_addrtype = af;
  result->h_length = size;

  /*
   * if there aren't any dots, it could be a user-level alias.
   * this is also done in res_query() since we are not the only
   * function that looks up host names.
   */
  if (strchr (name, '.') == NULL && (cp = __hostalias (name)) != NULL)
    name = cp;

  n = res_search (name, C_IN, type, host_buffer.buf, sizeof (host_buffer.buf));
  if (n < 0)
    {
      *h_errnop = h_errno;
      return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
    }

  return getanswer_r (&host_buffer, n, name, type, result, buffer, buflen,
		      h_errnop);
}


enum nss_status
_nss_dns_gethostbyname_r (const char *name, struct hostent *result,
			  char *buffer, size_t buflen, int *h_errnop)
{
  enum nss_status status = NSS_STATUS_NOTFOUND;

  if (_res.options & RES_USE_INET6)
    status = _nss_dns_gethostbyname2_r (name, AF_INET6, result, buffer,
					buflen, h_errnop);
  if (status == NSS_STATUS_NOTFOUND)
    status = _nss_dns_gethostbyname2_r (name, AF_INET, result, buffer,
					buflen, h_errnop);

  return status;
}


enum nss_status
_nss_dns_gethostbyaddr_r (const char *addr, int len, int af,
			  struct hostent *result, char *buffer, size_t buflen,
			  int *h_errnop)
{
  static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
  static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
  const u_char *uaddr = (const u_char *)addr;
  struct host_data
  {
    char *aliases[MAX_NR_ALIASES];
    unsigned char host_addr[16];	/* IPv4 or IPv6 */
    char *h_addr_ptrs[MAX_NR_ADDRS + 1];
    char linebuffer[0];
  } *host_data = (struct host_data *) buffer;
  querybuf host_buffer;
  char qbuf[MAXDNAME+1], *qp;
  int size, n, status;

  if (af == AF_INET6 && len == IN6ADDRSZ &&
      (memcmp (uaddr, mapped, sizeof mapped) == 0
       || memcmp (uaddr, tunnelled, sizeof tunnelled) == 0))
    {
      /* Unmap. */
      addr += sizeof mapped;
      uaddr += sizeof mapped;
      af = AF_INET;
      len = INADDRSZ;
    }

  switch (af)
    {
    case AF_INET:
      size = INADDRSZ;
      break;
    case AF_INET6:
      size = IN6ADDRSZ;
      break;
    default:
      __set_errno (EAFNOSUPPORT);
      *h_errnop = NETDB_INTERNAL;
      return NSS_STATUS_UNAVAIL;
    }
  if (size != len)
    {
      __set_errno (EAFNOSUPPORT);
      *h_errnop = NETDB_INTERNAL;
      return NSS_STATUS_UNAVAIL;
    }

  switch (af)
    {
    case AF_INET:
      sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", (uaddr[3] & 0xff),
	       (uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff));
      break;
    case AF_INET6:
      qp = qbuf;
      for (n = IN6ADDRSZ - 1; n >= 0; n--)
	qp += sprintf (qp, "%x.%x.", uaddr[n] & 0xf, (uaddr[n] >> 4) & 0xf);
      strcpy (qp, "ip6.int");
      break;
    default:
      /* Cannot happen.  */
    }

  n = res_query (qbuf, C_IN, T_PTR, (u_char *)host_buffer.buf,
		 sizeof host_buffer);
  if (n < 0)
    {
      *h_errnop = h_errno;
      return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
    }

  status = getanswer_r (&host_buffer, n, qbuf, T_PTR, result, buffer, buflen,
			h_errnop);
  if (status != NSS_STATUS_SUCCESS)
    {
      *h_errnop = h_errno;
      return status;
    }

#ifdef SUNSECURITY
  This is not implemented because it is not possible to use the current
  source from bind in a multi-threaded program.
#endif

  result->h_addrtype = af;
  result->h_length = len;
  memcpy (host_data->host_addr, addr, len);
  host_data->h_addr_ptrs[0] = (char *) host_data->host_addr;
  host_data->h_addr_ptrs[1] = NULL;
  if (af == AF_INET && (_res.options & RES_USE_INET6))
    {
      map_v4v6_address ((char *) host_data->host_addr,
			(char *) host_data->host_addr);
      result->h_addrtype = AF_INET6;
      result->h_length = IN6ADDRSZ;
    }
  *h_errnop = NETDB_SUCCESS;
  return NSS_STATUS_SUCCESS;
}


static enum nss_status
getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
	     struct hostent *result, char *buffer, size_t buflen,
	     int *h_errnop)
{
  struct host_data
  {
    char *aliases[MAX_NR_ALIASES];
    unsigned char host_addr[16];	/* IPv4 or IPv6 */
    char *h_addr_ptrs[MAX_NR_ADDRS + 1];
    char linebuffer[0];
  } *host_data = (struct host_data *) buffer;
  int linebuflen = buflen - offsetof (struct host_data, linebuffer);
  register const HEADER *hp;
  const u_char *end_of_message, *cp;
  int n, ancount, qdcount;
  int haveanswer, had_error;
  char *bp, **ap, **hap;
  char tbuf[MAXDNAME];
  const char *tname;
  int (*name_ok) __P ((const char *));

  tname = qname;
  result->h_name = NULL;
  end_of_message = answer->buf + anslen;
  switch (qtype)
    {
    case T_A:
    case T_AAAA:
      name_ok = res_hnok;
      break;
    case T_PTR:
      name_ok = res_dnok;
      break;
    default:
      return NSS_STATUS_UNAVAIL;  /* XXX should be abort(); */
    }

  /*
   * find first satisfactory answer
   */
  hp = &answer->hdr;
  bp = host_data->linebuffer;
  ancount = ntohs (hp->ancount);
  qdcount = ntohs (hp->qdcount);
  cp = answer->buf + HFIXEDSZ;
  if (qdcount != 1)
    {
      *h_errnop = NO_RECOVERY;
      return NSS_STATUS_UNAVAIL;
    }

  n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
  if (n < 0 || (*name_ok) (bp) == 0)
    {
      *h_errnop = NO_RECOVERY;
      return NSS_STATUS_UNAVAIL;
    }
  cp += n + QFIXEDSZ;

  if (qtype == T_A || qtype == T_AAAA)
    {
      /* res_send() has already verified that the query name is the
       * same as the one we sent; this just gets the expanded name
       * (i.e., with the succeeding search-domain tacked on).
       */
      n = strlen (bp) + 1;             /* for the \0 */
      if (n >= MAXHOSTNAMELEN)
	{
	  __set_h_errno (NO_RECOVERY);
	  return NSS_STATUS_TRYAGAIN;
	}
      result->h_name = bp;
      bp += n;
      linebuflen -= n;
      /* The qname can be abbreviated, but h_name is now absolute. */
      qname = result->h_name;
    }

  ap = host_data->aliases;
  *ap = NULL;
  result->h_aliases = host_data->aliases;
  hap = host_data->h_addr_ptrs;
  *hap = NULL;
  result->h_addr_list = host_data->h_addr_ptrs;
  haveanswer = 0;
  had_error = 0;

  while (ancount-- > 0 && cp < end_of_message && had_error == 0)
    {
      int type, class;

      n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
      if (n < 0 || (*name_ok) (bp) == 0)
	{
	  ++had_error;
	  continue;
	}
      cp += n;				/* name */
      type = _getshort (cp);
      cp += INT16SZ;			/* type */
      class = _getshort(cp);
      cp += INT16SZ + INT32SZ;		/* class, TTL */
      n = _getshort(cp);
      cp += INT16SZ;			/* len */
      if (class != C_IN)
	{
	  /* XXX - debug? syslog? */
	  cp += n;
	  continue;			/* XXX - had_error++ ? */
	}

      if ((qtype ==T_A || qtype == T_AAAA) && type == T_CNAME)
	{
	  if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1])
	    continue;
	  n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
	  if (n < 0 || (*name_ok) (tbuf) == 0)
	    {
	      ++had_error;
	      continue;
	    }
	  cp += n;
	  /* Store alias.  */
	  *ap++ = bp;
	  n = strlen (bp) + 1;		/* For the \0.  */
	  if (n >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  bp += n;
	  linebuflen -= n;
	  /* Get canonical name.  */
	  n = strlen (tbuf) + 1;	/* For the \0.  */
	  if ((size_t) n > buflen || n >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  result->h_name = strcpy (bp, tbuf);	/* Cannot overflow.  */
	  bp += n;
	  linebuflen -= n;
	  continue;
	}

      if (qtype == T_PTR && type == T_CNAME)
	{
	  n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
	  if (n < 0 || res_dnok (tbuf) == 0)
	    {
	      ++had_error;
	      continue;
	    }
	  cp += n;
	  /* Get canonical name.  */
	  n = strlen (tbuf) + 1;   /* For the \0.  */
	  if ((size_t) n > buflen || n >= MAXHOSTNAMELEN)
	    {
	      ++had_error;
	      continue;
	    }
	  tname = strcpy (bp, tbuf);	/* Cannot overflow.  */
	  bp += n;
	  linebuflen -= n;
	  continue;
	}
      if (type != qtype)
	{
	  syslog (LOG_NOTICE | LOG_AUTH,
	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
		  qname, p_class (C_IN), p_type (qtype), p_type (type));
	  cp += n;
	  continue;			/* XXX - had_error++ ? */
	}

      switch (type)
	{
	case T_PTR:
	  if (strcasecmp (tname, bp) != 0)
	    {
	      syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, qname, bp);
	      cp += n;
	      continue;			/* XXX - had_error++ ? */
	    }
	  n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
	  if (n < 0 || res_hnok (bp) == 0)
	    {
	      ++had_error;
	      break;
	    }
#if MULTI_PTRS_ARE_ALIASES
	  cp += n;
	  if (haveanswer == 0)
	    result->h_name = bp;
	  else if (ap < &host_data->aliases[MAXALIASES-1])
	    *ap++ = bp;
	  else
	    n = -1;
	  if (n != -1)
	    {
	      n = strlen (bp) + 1;	/* for the \0 */
	      if (n >= MAXHOSTNAMELEN)
		{
		  ++had_error;
		  break;
		}
	      bp += n;
	      linebuflen -= n;
	    }
	  break;
#else
	  result->h_name = bp;
	  if (_res.options & RES_USE_INET6)
	    {
	      n = strlen (bp) + 1;	/* for the \0 */
	      if (n >= MAXHOSTNAMELEN)
		{
		  ++had_error;
		  break;
		}
	      bp += n;
	      linebuflen -= n;
	      map_v4v6_hostent (result, &bp, &linebuflen);
	    }
	  *h_errnop = NETDB_SUCCESS;
	  return NSS_STATUS_SUCCESS;
#endif
	case T_A:
	case T_AAAA:
	  if (strcasecmp (result->h_name, bp) != 0)
	    {
	      syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, result->h_name, bp);
	      cp += n;
	      continue;			/* XXX - had_error++ ? */
	    }
	  if (n != result->h_length)
	    {
	      cp += n;
	      continue;
	    }
	  if (!haveanswer)
	    {
	      register int nn;

	      result->h_name = bp;
	      nn = strlen (bp) + 1;	/* for the \0 */
	      bp += nn;
	      linebuflen -= nn;
	    }

	  bp += sizeof (align) - ((u_long) bp % sizeof (align));

	  if (n >= linebuflen)
	    {
	      ++had_error;
	      continue;
	    }
	  if (hap >= &host_data->h_addr_ptrs[MAX_NR_ADDRS-1])
	    {
	      cp += n;
	      continue;
	    }
	  memcpy (*hap++ = bp, cp, n);
	  bp += n;
	  cp += n;
	  linebuflen -= n;
	  break;
	default:
	  abort ();
	}
      if (had_error == 0)
	++haveanswer;
    }

  if (haveanswer > 0)
    {
      *ap = NULL;
      *hap = NULL;
#if defined RESOLVSORT
      /*
       * Note: we sort even if host can take only one address
       * in its return structures - should give it the "best"
       * address in that case, not some random one
       */
      if (_res.nsort && haveanswer > 1 && qtype == T_A)
	addrsort (host_data->h_addr_ptrs, haveanswer);
#endif /*RESOLVSORT*/

      if (result->h_name == NULL)
	{
	  n = strlen (qname) + 1;	/* For the \0.  */
	  if (n > linebuflen || n >= MAXHOSTNAMELEN)
	    goto no_recovery;
	  result->h_name = strcpy (bp, qname);	/* Cannot overflow.  */
	  bp += n;
	  linebuflen -= n;
	}

      if (_res.options & RES_USE_INET6)
	map_v4v6_hostent (result, &bp, &linebuflen);
      *h_errnop = NETDB_SUCCESS;
      return NSS_STATUS_SUCCESS;
    }
 no_recovery:
  *h_errnop = NO_RECOVERY;
  return NSS_STATUS_TRYAGAIN;
}