summaryrefslogtreecommitdiff
path: root/resolv/nss_dns/dns-network.c
blob: 8e80a6010e1f25d86c2bdd48c3378ade70150db8 (plain)
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
/* Copyright (C) 1996-2014 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

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

/* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
 *      Dep. Matematica Universidade de Coimbra, Portugal, Europe
 *
 * 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.
 */
/*
 * Copyright (c) 1983, 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.
 * 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.
 */

#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#include "nsswitch.h"
#include <arpa/inet.h>

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


#if PACKETSZ > 65536
# define MAXPACKET	PACKETSZ
#else
# define MAXPACKET	65536
#endif


typedef enum
{
  BYADDR,
  BYNAME
} lookup_method;


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

/* These functions are defined in res_comp.c.  */
#define NS_MAXCDNAME	255	/* maximum compressed domain name */
extern int __ns_name_ntop (const u_char *, char *, size_t) __THROW;
extern int __ns_name_unpack (const u_char *, const u_char *,
			     const u_char *, u_char *, size_t) __THROW;


/* Prototypes for local functions.  */
static enum nss_status getanswer_r (const querybuf *answer, int anslen,
				    struct netent *result, char *buffer,
				    size_t buflen, int *errnop, int *h_errnop,
				    lookup_method net_i);


enum nss_status
_nss_dns_getnetbyname_r (const char *name, struct netent *result,
			 char *buffer, size_t buflen, int *errnop,
			 int *herrnop)
{
  /* Return entry for network with NAME.  */
  union
  {
    querybuf *buf;
    u_char *ptr;
  } net_buffer;
  querybuf *orig_net_buffer;
  int anslen;
  char *qbuf;
  enum nss_status status;

  if (__res_maybe_init (&_res, 0) == -1)
    return NSS_STATUS_UNAVAIL;

  qbuf = strdupa (name);

  net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);

  anslen = __libc_res_nsearch (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
			       1024, &net_buffer.ptr, NULL, NULL, NULL);
  if (anslen < 0)
    {
      /* Nothing found.  */
      *errnop = errno;
      if (net_buffer.buf != orig_net_buffer)
	free (net_buffer.buf);
      return (errno == ECONNREFUSED
	      || errno == EPFNOSUPPORT
	      || errno == EAFNOSUPPORT)
	? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
    }

  status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
			errnop, herrnop, BYNAME);
  if (net_buffer.buf != orig_net_buffer)
    free (net_buffer.buf);
  return status;
}


enum nss_status
_nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
			 char *buffer, size_t buflen, int *errnop,
			 int *herrnop)
{
  /* Return entry for network with NAME.  */
  enum nss_status status;
  union
  {
    querybuf *buf;
    u_char *ptr;
  } net_buffer;
  querybuf *orig_net_buffer;
  unsigned int net_bytes[4];
  char qbuf[MAXDNAME];
  int cnt, anslen;
  u_int32_t net2;
  int olderr = errno;

  /* No net address lookup for IPv6 yet.  */
  if (type != AF_INET)
    return NSS_STATUS_UNAVAIL;

  if (__res_maybe_init (&_res, 0) == -1)
    return NSS_STATUS_UNAVAIL;

  net2 = (u_int32_t) net;
  for (cnt = 4; net2 != 0; net2 >>= 8)
    net_bytes[--cnt] = net2 & 0xff;

  switch (cnt)
    {
    case 3:
      /* Class A network.  */
      sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
      break;
    case 2:
      /* Class B network.  */
      sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
      break;
    case 1:
      /* Class C network.  */
      sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
	       net_bytes[1]);
      break;
    case 0:
      /* Class D - E network.  */
      sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
	       net_bytes[1], net_bytes[0]);
      break;
    }

  net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);

  anslen = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
			      1024, &net_buffer.ptr, NULL, NULL, NULL);
  if (anslen < 0)
    {
      /* Nothing found.  */
      int err = errno;
      __set_errno (olderr);
      if (net_buffer.buf != orig_net_buffer)
	free (net_buffer.buf);
      return (err == ECONNREFUSED
	      || err == EPFNOSUPPORT
	      || err == EAFNOSUPPORT)
	? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
    }

  status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
			errnop, herrnop, BYADDR);
  if (net_buffer.buf != orig_net_buffer)
    free (net_buffer.buf);
  if (status == NSS_STATUS_SUCCESS)
    {
      /* Strip trailing zeros.  */
      unsigned int u_net = net;	/* Maybe net should be unsigned?  */

      while ((u_net & 0xff) == 0 && u_net != 0)
	u_net >>= 8;
      result->n_net = u_net;
    }

  return status;
}


#undef offsetof
#define offsetof(Type, Member) ((size_t) &((Type *) NULL)->Member)

static enum nss_status
getanswer_r (const querybuf *answer, int anslen, struct netent *result,
	     char *buffer, size_t buflen, int *errnop, int *h_errnop,
	     lookup_method net_i)
{
  /*
   * Find first satisfactory answer
   *
   *      answer --> +------------+  ( MESSAGE )
   *                 |   Header   |
   *                 +------------+
   *                 |  Question  | the question for the name server
   *                 +------------+
   *                 |   Answer   | RRs answering the question
   *                 +------------+
   *                 | Authority  | RRs pointing toward an authority
   *                 | Additional | RRs holding additional information
   *                 +------------+
   */
  struct net_data
  {
    char *aliases[MAX_NR_ALIASES];
    char linebuffer[0];
  } *net_data;

  uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
  buffer += pad;

  if (__builtin_expect (buflen < sizeof (*net_data) + pad, 0))
    {
      /* The buffer is too small.  */
    too_small:
      *errnop = ERANGE;
      *h_errnop = NETDB_INTERNAL;
      return NSS_STATUS_TRYAGAIN;
    }
  buflen -= pad;

  net_data = (struct net_data *) buffer;
  int linebuflen = buflen - offsetof (struct net_data, linebuffer);
  if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
    linebuflen = INT_MAX;
  const unsigned char *end_of_message = &answer->buf[anslen];
  const HEADER *header_pointer = &answer->hdr;
  /* #/records in the answer section.  */
  int answer_count =  ntohs (header_pointer->ancount);
  /* #/entries in the question section.  */
  int question_count = ntohs (header_pointer->qdcount);
  char *bp = net_data->linebuffer;
  const unsigned char *cp = &answer->buf[HFIXEDSZ];
  char **alias_pointer;
  int have_answer;
  u_char packtmp[NS_MAXCDNAME];

  if (question_count == 0)
    {
      /* FIXME: the Sun version uses for host name lookup an additional
	 parameter for pointing to h_errno.  this is missing here.
	 OSF/1 has a per-thread h_errno variable.  */
      if (header_pointer->aa != 0)
	{
	  __set_h_errno (HOST_NOT_FOUND);
	  return NSS_STATUS_NOTFOUND;
	}
      else
	{
	  __set_h_errno (TRY_AGAIN);
	  return NSS_STATUS_TRYAGAIN;
	}
    }

  /* Skip the question part.  */
  while (question_count-- > 0)
    {
      int n = __dn_skipname (cp, end_of_message);
      if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
       {
         __set_h_errno (NO_RECOVERY);
         return NSS_STATUS_UNAVAIL;
       }
      cp += n + QFIXEDSZ;
    }

  alias_pointer = result->n_aliases = &net_data->aliases[0];
  *alias_pointer = NULL;
  have_answer = 0;

  while (--answer_count >= 0 && cp < end_of_message)
    {
      int n = dn_expand (answer->buf, end_of_message, cp, bp, linebuflen);
      int type, class;

      n = __ns_name_unpack (answer->buf, end_of_message, cp,
			    packtmp, sizeof packtmp);
      if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
	{
	  if (errno == EMSGSIZE)
	    goto too_small;

	  n = -1;
	}

      if (n > 0 && bp[0] == '.')
	bp[0] = '\0';

      if (n < 0 || res_dnok (bp) == 0)
	break;
      cp += n;
      GETSHORT (type, cp);
      GETSHORT (class, cp);
      cp += INT32SZ;		/* TTL */
      GETSHORT (n, cp);

      if (class == C_IN && type == T_PTR)
	{
	  n = __ns_name_unpack (answer->buf, end_of_message, cp,
				packtmp, sizeof packtmp);
	  if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
	    {
	      if (errno == EMSGSIZE)
		goto too_small;

	      n = -1;
	    }

	  if (n < 0 || !res_hnok (bp))
	    {
	      /* XXX What does this mean?  The original form from bind
		 returns NULL. Incrementing cp has no effect in any case.
		 What should I return here. ??? */
	      cp += n;
	      return NSS_STATUS_UNAVAIL;
	    }
	  cp += n;
         if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
           {
             *alias_pointer++ = bp;
             n = strlen (bp) + 1;
             bp += n;
             linebuflen -= n;
             result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
             ++have_answer;
           }
	}
    }

  if (have_answer)
    {
      *alias_pointer = NULL;
      switch (net_i)
	{
	case BYADDR:
	  result->n_name = *result->n_aliases++;
	  result->n_net = 0L;
	  return NSS_STATUS_SUCCESS;

	case BYNAME:
	  {
	    char **ap = result->n_aliases++;
	    while (*ap != NULL)
	      {
		/* Check each alias name for being of the forms:
		   4.3.2.1.in-addr.arpa		= net 1.2.3.4
		   3.2.1.in-addr.arpa		= net 0.1.2.3
		   2.1.in-addr.arpa		= net 0.0.1.2
		   1.in-addr.arpa		= net 0.0.0.1
		*/
		uint32_t val = 0;	/* Accumulator for n_net value.  */
		unsigned int shift = 0; /* Which part we are parsing now.  */
		const char *p = *ap; /* Consuming the string.  */
		do
		  {
		    /* Match the leading 0 or 0[xX] base indicator.  */
		    unsigned int base = 10;
		    if (*p == '0' && p[1] != '.')
		      {
			base = 8;
			++p;
			if (*p == 'x' || *p == 'X')
			  {
			    base = 16;
			    ++p;
			    if (*p == '.')
			      break; /* No digit here.  Give up on alias.  */
			  }
			if (*p == '\0')
			  break;
		      }

		    uint32_t part = 0; /* Accumulates this part's number.  */
		    do
		      {
			if (isdigit (*p) && (*p - '0' < base))
			  part = (part * base) + (*p - '0');
			else if (base == 16 && isxdigit (*p))
			  part = (part << 4) + 10 + (tolower (*p) - 'a');
			++p;
		      } while (*p != '\0' && *p != '.');

		    if (*p != '.')
		      break;	/* Bad form.  Give up on this name.  */

		    /* Install this as the next more significant byte.  */
		    val |= part << shift;
		    shift += 8;
		    ++p;

		    /* If we are out of digits now, there are two cases:
		       1. We are done with digits and now see "in-addr.arpa".
		       2. This is not the droid we are looking for.  */
		    if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
		      {
			result->n_net = val;
			return NSS_STATUS_SUCCESS;
		      }

		    /* Keep going when we have seen fewer than 4 parts.  */
		  } while (shift < 32);
	      }
	  }
	  break;
	}
    }

  __set_h_errno (TRY_AGAIN);
  return NSS_STATUS_TRYAGAIN;
}