about summary refs log tree commit diff
path: root/nscd/nscd_gethst_r.c
blob: 407be1441f17be4c5c486eb8ecfde585431a314f (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
/* Copyright (C) 1998-2002, 2003, 2004 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/nameser.h>
#include <not-cancel.h>

#include "nscd-client.h"
#include "nscd_proto.h"

int __nss_not_use_nscd_hosts;

static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
			  struct hostent *resultbuf, char *buffer,
			  size_t buflen, struct hostent **result,
			  int *h_errnop) internal_function;


int
__nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
			char *buffer, size_t buflen, struct hostent **result,
			int *h_errnop)
{
  request_type reqtype;

  reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

  return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
			buffer, buflen, result, h_errnop);
}


int
__nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
			 char *buffer, size_t buflen, struct hostent **result,
			 int *h_errnop)
{
  request_type reqtype;

  reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

  return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
			buffer, buflen, result, h_errnop);
}


int
__nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
			struct hostent *resultbuf, char *buffer, size_t buflen,
			struct hostent **result, int *h_errnop)
{
  request_type reqtype;

  if (!((len == INADDRSZ && type == AF_INET)
	|| (len == IN6ADDRSZ && type == AF_INET6)))
    /* LEN and TYPE do not match.  */
    return -1;

  reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;

  return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
			h_errnop);
}


libc_locked_map_ptr (map_handle);
/* Note that we only free the structure if necessary.  The memory
   mapping is not removed since it is not visible to the malloc
   handling.  */
libc_freeres_fn (gr_map_free)
{
  if (map_handle.mapped != NO_MAPPING)
    free (map_handle.mapped);
}


static int
internal_function
nscd_gethst_r (const char *key, size_t keylen, request_type type,
	       struct hostent *resultbuf, char *buffer, size_t buflen,
	       struct hostent **result, int *h_errnop)
{
  int gc_cycle;
  int nretries = 0;

  /* If the mapping is available, try to search there instead of
     communicating with the nscd.  */
  struct mapped_database *mapped;
  mapped = __nscd_get_map_ref (GETFDHST, "hosts", &map_handle, &gc_cycle);

 retry:;
  const hst_response_header *hst_resp = NULL;
  const char *h_name = NULL;
  const uint32_t *aliases_len = NULL;
  const char *addr_list = NULL;
  size_t addr_list_len = 0;
  int retval = -1;
  const char *recend = (const char *) ~UINTMAX_C (0);
  int sock = -1;
  if (mapped != NO_MAPPING)
    {
      const struct datahead *found = __nscd_cache_search (type, key, keylen,
							  mapped);
      if (found != NULL)
	{
	  hst_resp = &found->data[0].hstdata;
	  h_name = (char *) (hst_resp + 1);
	  aliases_len = (uint32_t *) (h_name + hst_resp->h_name_len);
	  addr_list = ((char *) aliases_len
		       + hst_resp->h_aliases_cnt * sizeof (uint32_t));
	  addr_list_len = hst_resp->h_addr_list_cnt * INADDRSZ;

#ifndef _STRING_ARCH_unaligned
	  /* The aliases_len array in the mapped database might very
	     well be unaligned.  We will access it word-wise so on
	     platforms which do not tolerate unaligned accesses we
	     need to make an aligned copy.  */
	  if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
	      != 0)
	    {
	      uint32_t *tmp = alloca (hst_resp->h_aliases_cnt
				      * sizeof (uint32_t));
	      aliases_len = memcpy (tmp, aliases_len,
				    hst_resp->h_aliases_cnt
				    * sizeof (uint32_t));
	    }
#endif
	  if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
	    {
	      if (hst_resp->h_length == INADDRSZ)
		addr_list += addr_list_len;
	      addr_list_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;
	    }
	  recend = (const char *) found->data + found->recsize;
	  if (__builtin_expect ((const char *) addr_list + addr_list_len
				> recend, 0))
	    goto out_close;
	}
    }

  hst_response_header hst_resp_mem;
  if (hst_resp == NULL)
    {
      sock = __nscd_open_socket (key, keylen, type, &hst_resp_mem,
				 sizeof (hst_resp_mem));
      if (sock == -1)
	{
	  __nss_not_use_nscd_hosts = 1;
	  goto out;;
	}

      hst_resp = &hst_resp_mem;
    }

  /* No value found so far.  */
  *result = NULL;

  if (__builtin_expect (hst_resp->found == -1, 0))
    {
      /* The daemon does not cache this database.  */
      __nss_not_use_nscd_hosts = 1;
      goto out_close;
    }

  if (hst_resp->found == 1)
    {
      struct iovec vec[4];
      char *cp = buffer;
      uintptr_t align1;
      uintptr_t align2;
      size_t total_len;
      ssize_t cnt;
      char *ignore;
      int n;

      /* A first check whether the buffer is sufficiently large is possible.  */
      /* Now allocate the buffer the array for the group members.  We must
	 align the pointer and the base of the h_addr_list pointers.  */
      align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
		& (__alignof__ (char *) - 1));
      align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp->h_name_len)
					 - ((char *) 0)))
		& (__alignof__ (char *) - 1));
      if (buflen < (align1 + hst_resp->h_name_len + align2
		    + ((hst_resp->h_aliases_cnt + hst_resp->h_addr_list_cnt
			+ 2)
		       * sizeof (char *))
		    + hst_resp->h_addr_list_cnt * (type == AF_INET
						   ? INADDRSZ : IN6ADDRSZ)))
	{
	no_room:
	  __set_errno (ERANGE);
	  retval = ERANGE;
	  goto out_close;
	}
      cp += align1;

      /* Prepare the result as far as we can.  */
      resultbuf->h_aliases = (char **) cp;
      cp += (hst_resp->h_aliases_cnt + 1) * sizeof (char *);
      resultbuf->h_addr_list = (char **) cp;
      cp += (hst_resp->h_addr_list_cnt + 1) * sizeof (char *);

      resultbuf->h_name = cp;
      cp += hst_resp->h_name_len + align2;

      if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
	{
	  resultbuf->h_addrtype = AF_INET;
	  resultbuf->h_length = INADDRSZ;
	}
      else
	{
	  resultbuf->h_addrtype = AF_INET6;
	  resultbuf->h_length = IN6ADDRSZ;
	}
      for (cnt = 0; cnt < hst_resp->h_addr_list_cnt; ++cnt)
	{
	  resultbuf->h_addr_list[cnt] = cp;
	  cp += resultbuf->h_length;
	}
      resultbuf->h_addr_list[cnt] = NULL;

      if (h_name == NULL)
	{
	  vec[0].iov_base = resultbuf->h_name;
	  vec[0].iov_len = hst_resp->h_name_len;
	  total_len = hst_resp->h_name_len;
	  n = 1;

	  if (hst_resp->h_aliases_cnt > 0)
	    {
	      aliases_len = alloca (hst_resp->h_aliases_cnt
				    * sizeof (uint32_t));
	      vec[n].iov_base = (void *) aliases_len;
	      vec[n].iov_len = hst_resp->h_aliases_cnt * sizeof (uint32_t);

	      total_len += hst_resp->h_aliases_cnt * sizeof (uint32_t);
	      ++n;
	    }

	  if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
	    {
	      vec[n].iov_base = resultbuf->h_addr_list[0];
	      vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;

	      total_len += hst_resp->h_addr_list_cnt * INADDRSZ;

	      ++n;
	    }
	  else
	    {
	      if (hst_resp->h_length == INADDRSZ)
		{
		  ignore = alloca (hst_resp->h_addr_list_cnt * INADDRSZ);
		  vec[n].iov_base = ignore;
		  vec[n].iov_len = hst_resp->h_addr_list_cnt * INADDRSZ;

		  total_len += hst_resp->h_addr_list_cnt * INADDRSZ;

		  ++n;
		}

	      vec[n].iov_base = resultbuf->h_addr_list[0];
	      vec[n].iov_len = hst_resp->h_addr_list_cnt * IN6ADDRSZ;

	      total_len += hst_resp->h_addr_list_cnt * IN6ADDRSZ;

	      ++n;
	    }

	  if ((size_t) TEMP_FAILURE_RETRY (__readv (sock, vec, n))
	      != total_len)
	    goto out_close;
	}
      else
	{
	  memcpy (resultbuf->h_name, h_name, hst_resp->h_name_len);
	  memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
	}

      /*  Now we also can read the aliases.  */
      total_len = 0;
      for (cnt = 0; cnt < hst_resp->h_aliases_cnt; ++cnt)
	{
	  resultbuf->h_aliases[cnt] = cp;
	  cp += aliases_len[cnt];
	  total_len += aliases_len[cnt];
	}
      resultbuf->h_aliases[cnt] = NULL;

      if (__builtin_expect ((const char *) addr_list + addr_list_len
			    + total_len > recend, 0))
	goto out_close;
      /* See whether this would exceed the buffer capacity.  */
      if (__builtin_expect (cp > buffer + buflen, 0))
	goto no_room;

      /* And finally read the aliases.  */
      if (addr_list == NULL)
	{
	  if ((size_t) TEMP_FAILURE_RETRY (__read (sock,
						   resultbuf->h_aliases[0],
						   total_len)) == total_len)
	    {
	      retval = 0;
	      *result = resultbuf;
	    }
	}
      else
	{
	  memcpy (resultbuf->h_aliases[0],
		  (const char *) addr_list + addr_list_len, total_len);

	  retval = 0;
	  *result = resultbuf;
	}
    }
  else
    {
      /* Store the error number.  */
      *h_errnop = hst_resp->error;

      /* The `errno' to some value != ERANGE.  */
      __set_errno (ENOENT);
      /* Even though we have not found anything, the result is zero.  */
      retval = 0;
    }

 out_close:
  if (sock != -1)
    close_not_cancel_no_status (sock);
 out:
  if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
    {
      /* When we come here this means there has been a GC cycle while we
	 were looking for the data.  This means the data might have been
	 inconsistent.  Retry if possible.  */
      if ((gc_cycle & 1) != 0 || ++nretries == 5)
	{
	  /* nscd is just running gc now.  Disable using the mapping.  */
	  __nscd_unmap (mapped);
	  mapped = NO_MAPPING;
	}

      goto retry;
    }

  return retval;
}