about summary refs log tree commit diff
path: root/nss/nss_files/files-hosts.c
blob: da5967a87dddf1fb0488049204236217727923ed (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
/* Hosts file parser in nss_files module.
   Copyright (C) 1996-2019 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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/>.  */

#include <assert.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv/resolv-internal.h>
#include <scratch_buffer.h>
#include <alloc_buffer.h>


/* Get implementation for some internal functions.  */
#include "../resolv/res_hconf.h"


#define ENTNAME		hostent
#define DATABASE	"hosts"
#define NEED_H_ERRNO

#define EXTRA_ARGS	 , af
#define EXTRA_ARGS_DECL	 , int af

#define ENTDATA hostent_data
struct hostent_data
  {
    unsigned char host_addr[16]; /* IPv4 or IPv6 address.  */
    char *h_addr_ptrs[2];	/* Points to that and null terminator.  */
  };

#define TRAILING_LIST_MEMBER		h_aliases
#define TRAILING_LIST_SEPARATOR_P	isspace
#include "files-parse.c"
LINE_PARSER
("#",
 {
   char *addr;

   STRING_FIELD (addr, isspace, 1);

   /* Parse address.  */
   if (inet_pton (af == AF_UNSPEC ? AF_INET : af, addr, entdata->host_addr)
       > 0)
     af = af == AF_UNSPEC ? AF_INET : af;
   else
     {
       if (af == AF_INET && inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
	 {
	   if (IN6_IS_ADDR_V4MAPPED (entdata->host_addr))
	     memcpy (entdata->host_addr, entdata->host_addr + 12, INADDRSZ);
	   else if (IN6_IS_ADDR_LOOPBACK (entdata->host_addr))
	     {
	       in_addr_t localhost = htonl (INADDR_LOOPBACK);
	       memcpy (entdata->host_addr, &localhost, sizeof (localhost));
	     }
	   else
	     /* Illegal address: ignore line.  */
	     return 0;
	 }
       else if (af == AF_UNSPEC
		&& inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
	 af = AF_INET6;
       else
	 /* Illegal address: ignore line.  */
	 return 0;
     }

   /* We always return entries of the requested form.  */
   result->h_addrtype = af;
   result->h_length = af == AF_INET ? INADDRSZ : IN6ADDRSZ;

   /* Store a pointer to the address in the expected form.  */
   entdata->h_addr_ptrs[0] = (char *) entdata->host_addr;
   entdata->h_addr_ptrs[1] = NULL;
   result->h_addr_list = entdata->h_addr_ptrs;

   STRING_FIELD (result->h_name, isspace, 1);
 })

#define EXTRA_ARGS_VALUE , AF_INET
#include "files-XXX.c"
#undef EXTRA_ARGS_VALUE

/* We only need to consider IPv4 mapped addresses if the input to the
   gethostbyaddr() function is an IPv6 address.  */
#define EXTRA_ARGS_VALUE , af
DB_LOOKUP (hostbyaddr, ,,,
	   {
	     if (result->h_length == (int) len
		 && ! memcmp (addr, result->h_addr_list[0], len))
	       break;
	   }, const void *addr, socklen_t len, int af)
#undef EXTRA_ARGS_VALUE

/* Type of the address and alias arrays.  */
#define DYNARRAY_STRUCT array
#define DYNARRAY_ELEMENT char *
#define DYNARRAY_PREFIX array_
#include <malloc/dynarray-skeleton.c>

static enum nss_status
gethostbyname3_multi (FILE * stream, const char *name, int af,
		      struct hostent *result, char *buffer, size_t buflen,
		      int *errnop, int *herrnop)
{
  assert (af == AF_INET || af == AF_INET6);

  /* We have to get all host entries from the file.  */
  struct scratch_buffer tmp_buffer;
  scratch_buffer_init (&tmp_buffer);
  struct hostent tmp_result_buf;
  struct array addresses;
  array_init (&addresses);
  struct array aliases;
  array_init (&aliases);
  enum nss_status status;

  /* Preserve the addresses and aliases encountered so far.  */
  for (size_t i = 0; result->h_addr_list[i] != NULL; ++i)
    array_add (&addresses, result->h_addr_list[i]);
  for (size_t i = 0; result->h_aliases[i] != NULL; ++i)
    array_add (&aliases, result->h_aliases[i]);

  /* The output buffer re-uses now-unused space at the end of the
     buffer, starting with the aliases array.  It comes last in the
     data produced by internal_getent.  (The alias names themselves
     are still located in the line read in internal_getent, which is
     stored at the beginning of the buffer.)  */
  struct alloc_buffer outbuf;
  {
    char *bufferend = (char *) result->h_aliases;
    outbuf = alloc_buffer_create (bufferend, buffer + buflen - bufferend);
  }

  while (true)
    {
      status = internal_getent (stream, &tmp_result_buf, tmp_buffer.data,
				tmp_buffer.length, errnop, herrnop, af);
      /* Enlarge the buffer if necessary.  */
      if (status == NSS_STATUS_TRYAGAIN && *herrnop == NETDB_INTERNAL
	  && *errnop == ERANGE)
	{
	  if (!scratch_buffer_grow (&tmp_buffer))
	    {
	      *errnop = ENOMEM;
	      /* *herrnop and status already have the right value.  */
	      break;
	    }
	  /* Loop around and retry with a larger buffer.  */
	}
      else if (status == NSS_STATUS_SUCCESS)
	{
	  /* A line was read.  Check that it matches the search
	     criteria.  */

	  int matches = 1;
	  struct hostent *old_result = result;
	  result = &tmp_result_buf;
	  /* The following piece is a bit clumsy but we want to use
	     the `LOOKUP_NAME_CASE' value.  The optimizer should do
	     its job.  */
	  do
	    {
	      LOOKUP_NAME_CASE (h_name, h_aliases)
		result = old_result;
	    }
	  while ((matches = 0));

	  /* If the line matches, we need to copy the addresses and
	     aliases, so that we can reuse tmp_buffer for the next
	     line.  */
	  if (matches)
	    {
	      /* Record the addresses.  */
	      for (size_t i = 0; tmp_result_buf.h_addr_list[i] != NULL; ++i)
		{
		  /* Allocate the target space in the output buffer,
		     depending on the address family.  */
		  void *target;
		  if (af == AF_INET)
		    {
		      assert (tmp_result_buf.h_length == 4);
		      target = alloc_buffer_alloc (&outbuf, struct in_addr);
		    }
		  else if (af == AF_INET6)
		    {
		      assert (tmp_result_buf.h_length == 16);
		      target = alloc_buffer_alloc (&outbuf, struct in6_addr);
		    }
		  else
		    __builtin_unreachable ();

		  if (target == NULL)
		    {
		      /* Request a larger output buffer.  */
		      *errnop = ERANGE;
		      *herrnop = NETDB_INTERNAL;
		      status = NSS_STATUS_TRYAGAIN;
		      break;
		    }
		  memcpy (target, tmp_result_buf.h_addr_list[i],
			  tmp_result_buf.h_length);
		  array_add (&addresses, target);
		}

	      /* Record the aliases.  */
	      for (size_t i = 0; tmp_result_buf.h_aliases[i] != NULL; ++i)
		{
		  char *alias = tmp_result_buf.h_aliases[i];
		  array_add (&aliases,
			     alloc_buffer_copy_string (&outbuf, alias));
		}

	      /* If the real name is different add, it also to the
		 aliases.  This means that there is a duplication in
		 the alias list but this is really the user's
		 problem.  */
	      {
		char *new_name = tmp_result_buf.h_name;
		if (strcmp (old_result->h_name, new_name) != 0)
		  array_add (&aliases,
			     alloc_buffer_copy_string (&outbuf, new_name));
	      }

	      /* Report memory allocation failures during the
		 expansion of the temporary arrays.  */
	      if (array_has_failed (&addresses) || array_has_failed (&aliases))
		{
		  *errnop = ENOMEM;
		  *herrnop = NETDB_INTERNAL;
		  status = NSS_STATUS_UNAVAIL;
		  break;
		}

	      /* Request a larger output buffer if we ran out of room.  */
	      if (alloc_buffer_has_failed (&outbuf))
		{
		  *errnop = ERANGE;
		  *herrnop = NETDB_INTERNAL;
		  status = NSS_STATUS_TRYAGAIN;
		  break;
		}

	      result = old_result;
	    } /* If match was found.  */

	  /* If no match is found, loop around and fetch another
	     line.  */

	} /* status == NSS_STATUS_SUCCESS.  */
      else
	/* internal_getent returned an error.  */
	break;
    } /* while (true) */

  /* Propagate the NSS_STATUS_TRYAGAIN error to the caller.  It means
     that we may not have loaded the complete result.
     NSS_STATUS_NOTFOUND, however, means that we reached the end of
     the file successfully.  */
  if (status != NSS_STATUS_TRYAGAIN)
    status = NSS_STATUS_SUCCESS;

  if (status == NSS_STATUS_SUCCESS)
    {
      /* Copy the address and alias arrays into the output buffer and
	 add NULL terminators.  The pointed-to elements were directly
	 written into the output buffer above and do not need to be
	 copied again.  */
      size_t addresses_count = array_size (&addresses);
      size_t aliases_count = array_size (&aliases);
      char **out_addresses = alloc_buffer_alloc_array
	(&outbuf, char *, addresses_count + 1);
      char **out_aliases = alloc_buffer_alloc_array
	(&outbuf, char *, aliases_count + 1);
      if (out_addresses == NULL || out_aliases == NULL)
	{
	  /* The output buffer is not large enough.  */
	  *errnop = ERANGE;
	  *herrnop = NETDB_INTERNAL;
	  status = NSS_STATUS_TRYAGAIN;
	  /* Fall through to function exit.  */
	}
      else
	{
	  /* Everything is allocated in place.  Make the copies and
	     adjust the array pointers.  */
	  memcpy (out_addresses, array_begin (&addresses),
		  addresses_count * sizeof (char *));
	  out_addresses[addresses_count] = NULL;
	  memcpy (out_aliases, array_begin (&aliases),
		  aliases_count * sizeof (char *));
	  out_aliases[aliases_count] = NULL;

	  result->h_addr_list = out_addresses;
	  result->h_aliases = out_aliases;

	  status = NSS_STATUS_SUCCESS;
	}
    }

  scratch_buffer_free (&tmp_buffer);
  array_free (&addresses);
  array_free (&aliases);
  return status;
}

enum nss_status
_nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
			     char *buffer, size_t buflen, int *errnop,
			     int *herrnop, int32_t *ttlp, char **canonp)
{
  FILE *stream = NULL;
  uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct hostent_data);
  buffer += pad;
  buflen = buflen > pad ? buflen - pad : 0;

  /* Open file.  */
  enum nss_status status = internal_setent (&stream);

  if (status == NSS_STATUS_SUCCESS)
    {
      while ((status = internal_getent (stream, result, buffer, buflen, errnop,
					herrnop, af))
	     == NSS_STATUS_SUCCESS)
	{
	  LOOKUP_NAME_CASE (h_name, h_aliases)
	}

      if (status == NSS_STATUS_SUCCESS
	  && _res_hconf.flags & HCONF_FLAG_MULTI)
	status = gethostbyname3_multi
	  (stream, name, af, result, buffer, buflen, errnop, herrnop);

      internal_endent (&stream);
    }

  if (canonp && status == NSS_STATUS_SUCCESS)
    *canonp = result->h_name;

  return status;
}

enum nss_status
_nss_files_gethostbyname_r (const char *name, struct hostent *result,
			    char *buffer, size_t buflen, int *errnop,
			    int *herrnop)
{
  return _nss_files_gethostbyname3_r (name, AF_INET, result, buffer, buflen,
				      errnop, herrnop, NULL, NULL);
}

enum nss_status
_nss_files_gethostbyname2_r (const char *name, int af, struct hostent *result,
			     char *buffer, size_t buflen, int *errnop,
			     int *herrnop)
{
  return _nss_files_gethostbyname3_r (name, af, result, buffer, buflen,
				      errnop, herrnop, NULL, NULL);
}

enum nss_status
_nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
			     char *buffer, size_t buflen, int *errnop,
			     int *herrnop, int32_t *ttlp)
{
  FILE *stream = NULL;

  /* Open file.  */
  enum nss_status status = internal_setent (&stream);

  if (status == NSS_STATUS_SUCCESS)
    {
      bool any = false;
      bool got_canon = false;
      while (1)
	{
	  /* Align the buffer for the next record.  */
	  uintptr_t pad = (-(uintptr_t) buffer
			   % __alignof__ (struct hostent_data));
	  buffer += pad;
	  buflen = buflen > pad ? buflen - pad : 0;

	  struct hostent result;
	  status = internal_getent (stream, &result, buffer, buflen, errnop,
				    herrnop, AF_UNSPEC);
	  if (status != NSS_STATUS_SUCCESS)
	    break;

	  int naliases = 0;
	  if (__strcasecmp (name, result.h_name) != 0)
	    {
	      for (; result.h_aliases[naliases] != NULL; ++naliases)
		if (! __strcasecmp (name, result.h_aliases[naliases]))
		  break;
	      if (result.h_aliases[naliases] == NULL)
		continue;

	      /* We know this alias exist.  Count it.  */
	      ++naliases;
	    }

	  /* Determine how much memory has been used so far.  */
	  // XXX It is not necessary to preserve the aliases array
	  while (result.h_aliases[naliases] != NULL)
	    ++naliases;
	  char *bufferend = (char *) &result.h_aliases[naliases + 1];
	  assert (buflen >= bufferend - buffer);
	  buflen -= bufferend - buffer;
	  buffer = bufferend;

	  /* We found something.  */
	  any = true;

	  /* Create the record the caller expects.  There is only one
	     address.  */
	  assert (result.h_addr_list[1] == NULL);
	  if (*pat == NULL)
	    {
	      uintptr_t pad = (-(uintptr_t) buffer
			       % __alignof__ (struct gaih_addrtuple));
	      buffer += pad;
	      buflen = buflen > pad ? buflen - pad : 0;

	      if (__builtin_expect (buflen < sizeof (struct gaih_addrtuple),
				    0))
		{
		  *errnop = ERANGE;
		  *herrnop = NETDB_INTERNAL;
		  status = NSS_STATUS_TRYAGAIN;
		  break;
		}

	      *pat = (struct gaih_addrtuple *) buffer;
	      buffer += sizeof (struct gaih_addrtuple);
	      buflen -= sizeof (struct gaih_addrtuple);
	    }

	  (*pat)->next = NULL;
	  (*pat)->name = got_canon ? NULL : result.h_name;
	  got_canon = true;
	  (*pat)->family = result.h_addrtype;
	  memcpy ((*pat)->addr, result.h_addr_list[0], result.h_length);
	  (*pat)->scopeid = 0;

	  pat = &((*pat)->next);

	  /* If we only look for the first matching entry we are done.  */
	  if ((_res_hconf.flags & HCONF_FLAG_MULTI) == 0)
	    break;
	}

      /* If we have to look for multiple records and found one, this
	 is a success.  */
      if (status == NSS_STATUS_NOTFOUND && any)
	{
	  assert ((_res_hconf.flags & HCONF_FLAG_MULTI) != 0);
	  status = NSS_STATUS_SUCCESS;
	}

      internal_endent (&stream);
    }
  else if (status == NSS_STATUS_TRYAGAIN)
    {
      *errnop = errno;
      *herrnop = TRY_AGAIN;
    }
  else
    {
      *errnop = errno;
      *herrnop = NO_DATA;
    }

  return status;
}