1/* Copyright (C) 1996-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* Parts of this file are plain copies of the file `getnetnamadr.c' from
20 the bind package and it has the following copyright. */
21
22/* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
23 * Dep. Matematica Universidade de Coimbra, Portugal, Europe
24 *
25 * Permission to use, copy, modify, and distribute this software for any
26 * purpose with or without fee is hereby granted, provided that the above
27 * copyright notice and this permission notice appear in all copies.
28 */
29/*
30 * Copyright (c) 1983, 1993
31 * The Regents of the University of California. All rights reserved.
32 *
33 * Redistribution and use in source and binary forms, with or without
34 * modification, are permitted provided that the following conditions
35 * are met:
36 * 1. Redistributions of source code must retain the above copyright
37 * notice, this list of conditions and the following disclaimer.
38 * 2. Redistributions in binary form must reproduce the above copyright
39 * notice, this list of conditions and the following disclaimer in the
40 * documentation and/or other materials provided with the distribution.
41 * 4. Neither the name of the University nor the names of its contributors
42 * may be used to endorse or promote products derived from this software
43 * without specific prior written permission.
44 *
45 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
48 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
55 * SUCH DAMAGE.
56 */
57
58#include <ctype.h>
59#include <errno.h>
60#include <netdb.h>
61#include <stdio.h>
62#include <stdlib.h>
63#include <string.h>
64#include <stdint.h>
65#include <stddef.h>
66
67#include "nsswitch.h"
68#include <arpa/inet.h>
69#include <arpa/nameser.h>
70#include <resolv/resolv-internal.h>
71#include <resolv/resolv_context.h>
72
73NSS_DECLARE_MODULE_FUNCTIONS (dns)
74
75/* Maximum number of aliases we allow. */
76#define MAX_NR_ALIASES 48
77
78
79#if PACKETSZ > 65536
80# define MAXPACKET PACKETSZ
81#else
82# define MAXPACKET 65536
83#endif
84
85
86typedef enum
87{
88 BYADDR,
89 BYNAME
90} lookup_method;
91
92
93/* We need this time later. */
94typedef union querybuf
95{
96 HEADER hdr;
97 u_char buf[MAXPACKET];
98} querybuf;
99
100/* Prototypes for local functions. */
101static enum nss_status getanswer_r (const querybuf *answer, int anslen,
102 struct netent *result, char *buffer,
103 size_t buflen, int *errnop, int *h_errnop,
104 lookup_method net_i);
105
106
107enum nss_status
108_nss_dns_getnetbyname_r (const char *name, struct netent *result,
109 char *buffer, size_t buflen, int *errnop,
110 int *herrnop)
111{
112 /* Return entry for network with NAME. */
113 union
114 {
115 querybuf *buf;
116 u_char *ptr;
117 } net_buffer;
118 querybuf *orig_net_buffer;
119 int anslen;
120 enum nss_status status;
121
122 struct resolv_context *ctx = __resolv_context_get ();
123 if (ctx == NULL)
124 {
125 *errnop = errno;
126 *herrnop = NETDB_INTERNAL;
127 return NSS_STATUS_UNAVAIL;
128 }
129
130 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
131
132 anslen = __res_context_search
133 (ctx, name, C_IN, T_PTR, net_buffer.buf->buf,
134 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
135 if (anslen < 0)
136 {
137 /* Nothing found. */
138 *errnop = errno;
139 if (net_buffer.buf != orig_net_buffer)
140 free (net_buffer.buf);
141 __resolv_context_put (ctx);
142 return (errno == ECONNREFUSED
143 || errno == EPFNOSUPPORT
144 || errno == EAFNOSUPPORT)
145 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
146 }
147
148 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
149 errnop, herrnop, BYNAME);
150 if (net_buffer.buf != orig_net_buffer)
151 free (net_buffer.buf);
152 __resolv_context_put (ctx);
153 return status;
154}
155
156
157enum nss_status
158_nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
159 char *buffer, size_t buflen, int *errnop,
160 int *herrnop)
161{
162 /* Return entry for network with NAME. */
163 enum nss_status status;
164 union
165 {
166 querybuf *buf;
167 u_char *ptr;
168 } net_buffer;
169 querybuf *orig_net_buffer;
170 unsigned int net_bytes[4];
171 char qbuf[MAXDNAME];
172 int cnt, anslen;
173 uint32_t net2;
174 int olderr = errno;
175
176 /* No net address lookup for IPv6 yet. */
177 if (type != AF_INET)
178 return NSS_STATUS_UNAVAIL;
179
180 struct resolv_context *ctx = __resolv_context_get ();
181 if (ctx == NULL)
182 {
183 *errnop = errno;
184 *herrnop = NETDB_INTERNAL;
185 return NSS_STATUS_UNAVAIL;
186 }
187
188 net2 = (uint32_t) net;
189 for (cnt = 4; net2 != 0; net2 >>= 8)
190 net_bytes[--cnt] = net2 & 0xff;
191
192 switch (cnt)
193 {
194 case 3:
195 /* Class A network. */
196 sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
197 break;
198 case 2:
199 /* Class B network. */
200 sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
201 break;
202 case 1:
203 /* Class C network. */
204 sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
205 net_bytes[1]);
206 break;
207 case 0:
208 /* Class D - E network. */
209 sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
210 net_bytes[1], net_bytes[0]);
211 break;
212 }
213
214 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
215
216 anslen = __res_context_query (ctx, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
217 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
218 if (anslen < 0)
219 {
220 /* Nothing found. */
221 int err = errno;
222 __set_errno (olderr);
223 if (net_buffer.buf != orig_net_buffer)
224 free (net_buffer.buf);
225 __resolv_context_put (ctx);
226 return (err == ECONNREFUSED
227 || err == EPFNOSUPPORT
228 || err == EAFNOSUPPORT)
229 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
230 }
231
232 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
233 errnop, herrnop, BYADDR);
234 if (net_buffer.buf != orig_net_buffer)
235 free (net_buffer.buf);
236 if (status == NSS_STATUS_SUCCESS)
237 {
238 /* Strip trailing zeros. */
239 unsigned int u_net = net; /* Maybe net should be unsigned? */
240
241 while ((u_net & 0xff) == 0 && u_net != 0)
242 u_net >>= 8;
243 result->n_net = u_net;
244 }
245
246 __resolv_context_put (ctx);
247 return status;
248}
249
250
251static enum nss_status
252getanswer_r (const querybuf *answer, int anslen, struct netent *result,
253 char *buffer, size_t buflen, int *errnop, int *h_errnop,
254 lookup_method net_i)
255{
256 /*
257 * Find first satisfactory answer
258 *
259 * answer --> +------------+ ( MESSAGE )
260 * | Header |
261 * +------------+
262 * | Question | the question for the name server
263 * +------------+
264 * | Answer | RRs answering the question
265 * +------------+
266 * | Authority | RRs pointing toward an authority
267 * | Additional | RRs holding additional information
268 * +------------+
269 */
270 struct net_data
271 {
272 char *aliases[MAX_NR_ALIASES];
273 char linebuffer[0];
274 } *net_data;
275
276 uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
277 buffer += pad;
278
279 if (__glibc_unlikely (buflen < sizeof (*net_data) + pad))
280 {
281 /* The buffer is too small. */
282 too_small:
283 *errnop = ERANGE;
284 *h_errnop = NETDB_INTERNAL;
285 return NSS_STATUS_TRYAGAIN;
286 }
287 buflen -= pad;
288
289 net_data = (struct net_data *) buffer;
290 int linebuflen = buflen - offsetof (struct net_data, linebuffer);
291 if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
292 linebuflen = INT_MAX;
293 const unsigned char *end_of_message = &answer->buf[anslen];
294 const HEADER *header_pointer = &answer->hdr;
295 /* #/records in the answer section. */
296 int answer_count = ntohs (header_pointer->ancount);
297 /* #/entries in the question section. */
298 int question_count = ntohs (header_pointer->qdcount);
299 char *bp = net_data->linebuffer;
300 const unsigned char *cp = &answer->buf[HFIXEDSZ];
301 char **alias_pointer;
302 int have_answer;
303 u_char packtmp[NS_MAXCDNAME];
304
305 if (question_count == 0)
306 {
307 /* FIXME: the Sun version uses for host name lookup an additional
308 parameter for pointing to h_errno. this is missing here.
309 OSF/1 has a per-thread h_errno variable. */
310 if (header_pointer->aa != 0)
311 {
312 __set_h_errno (HOST_NOT_FOUND);
313 return NSS_STATUS_NOTFOUND;
314 }
315 else
316 {
317 __set_h_errno (TRY_AGAIN);
318 return NSS_STATUS_TRYAGAIN;
319 }
320 }
321
322 /* Skip the question part. */
323 while (question_count-- > 0)
324 {
325 int n = __dn_skipname (cp, end_of_message);
326 if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
327 {
328 __set_h_errno (NO_RECOVERY);
329 return NSS_STATUS_UNAVAIL;
330 }
331 cp += n + QFIXEDSZ;
332 }
333
334 alias_pointer = result->n_aliases = &net_data->aliases[0];
335 *alias_pointer = NULL;
336 have_answer = 0;
337
338 while (--answer_count >= 0 && cp < end_of_message)
339 {
340 int n = __ns_name_unpack (answer->buf, end_of_message, cp,
341 packtmp, sizeof packtmp);
342 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
343 {
344 if (errno == EMSGSIZE)
345 goto too_small;
346
347 n = -1;
348 }
349
350 if (n < 0 || res_dnok (bp) == 0)
351 break;
352 cp += n;
353
354 if (end_of_message - cp < 10)
355 {
356 __set_h_errno (NO_RECOVERY);
357 return NSS_STATUS_UNAVAIL;
358 }
359
360 int type, class;
361 GETSHORT (type, cp);
362 GETSHORT (class, cp);
363 cp += INT32SZ; /* TTL */
364 uint16_t rdatalen;
365 GETSHORT (rdatalen, cp);
366 if (end_of_message - cp < rdatalen)
367 {
368 __set_h_errno (NO_RECOVERY);
369 return NSS_STATUS_UNAVAIL;
370 }
371
372 if (class == C_IN && type == T_PTR)
373 {
374 n = __ns_name_unpack (answer->buf, end_of_message, cp,
375 packtmp, sizeof packtmp);
376 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
377 {
378 if (errno == EMSGSIZE)
379 goto too_small;
380
381 n = -1;
382 }
383
384 if (n < 0 || !res_hnok (bp))
385 {
386 /* XXX What does this mean? The original form from bind
387 returns NULL. Incrementing cp has no effect in any case.
388 What should I return here. ??? */
389 cp += n;
390 return NSS_STATUS_UNAVAIL;
391 }
392 cp += rdatalen;
393 if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
394 {
395 *alias_pointer++ = bp;
396 n = strlen (bp) + 1;
397 bp += n;
398 linebuflen -= n;
399 result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
400 ++have_answer;
401 }
402 }
403 else
404 /* Skip over unknown record data. */
405 cp += rdatalen;
406 }
407
408 if (have_answer)
409 {
410 *alias_pointer = NULL;
411 switch (net_i)
412 {
413 case BYADDR:
414 result->n_name = *result->n_aliases++;
415 result->n_net = 0L;
416 return NSS_STATUS_SUCCESS;
417
418 case BYNAME:
419 {
420 char **ap;
421 for (ap = result->n_aliases; *ap != NULL; ++ap)
422 {
423 /* Check each alias name for being of the forms:
424 4.3.2.1.in-addr.arpa = net 1.2.3.4
425 3.2.1.in-addr.arpa = net 0.1.2.3
426 2.1.in-addr.arpa = net 0.0.1.2
427 1.in-addr.arpa = net 0.0.0.1
428 */
429 uint32_t val = 0; /* Accumulator for n_net value. */
430 unsigned int shift = 0; /* Which part we are parsing now. */
431 const char *p = *ap; /* Consuming the string. */
432 do
433 {
434 /* Match the leading 0 or 0[xX] base indicator. */
435 unsigned int base = 10;
436 if (*p == '0' && p[1] != '.')
437 {
438 base = 8;
439 ++p;
440 if (*p == 'x' || *p == 'X')
441 {
442 base = 16;
443 ++p;
444 if (*p == '.')
445 break; /* No digit here. Give up on alias. */
446 }
447 if (*p == '\0')
448 break;
449 }
450
451 uint32_t part = 0; /* Accumulates this part's number. */
452 do
453 {
454 if (isdigit (*p) && (*p - '0' < base))
455 part = (part * base) + (*p - '0');
456 else if (base == 16 && isxdigit (*p))
457 part = (part << 4) + 10 + (tolower (*p) - 'a');
458 ++p;
459 } while (*p != '\0' && *p != '.');
460
461 if (*p != '.')
462 break; /* Bad form. Give up on this name. */
463
464 /* Install this as the next more significant byte. */
465 val |= part << shift;
466 shift += 8;
467 ++p;
468
469 /* If we are out of digits now, there are two cases:
470 1. We are done with digits and now see "in-addr.arpa".
471 2. This is not the droid we are looking for. */
472 if (!isdigit (*p) && !strcasecmp (p, "in-addr.arpa"))
473 {
474 result->n_net = val;
475 return NSS_STATUS_SUCCESS;
476 }
477
478 /* Keep going when we have seen fewer than 4 parts. */
479 } while (shift < 32);
480 }
481 }
482 break;
483 }
484 }
485
486 __set_h_errno (TRY_AGAIN);
487 return NSS_STATUS_TRYAGAIN;
488}
489