1/* Copyright (C) 1996-2022 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18/* Parts of this file are plain copies of the file `getnetnamadr.c' from
19 the bind package and it has the following copyright. */
20
21/* Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
22 * Dep. Matematica Universidade de Coimbra, Portugal, Europe
23 *
24 * Permission to use, copy, modify, and distribute this software for any
25 * purpose with or without fee is hereby granted, provided that the above
26 * copyright notice and this permission notice appear in all copies.
27 */
28/*
29 * Copyright (c) 1983, 1993
30 * The Regents of the University of California. All rights reserved.
31 *
32 * Redistribution and use in source and binary forms, with or without
33 * modification, are permitted provided that the following conditions
34 * are met:
35 * 1. Redistributions of source code must retain the above copyright
36 * notice, this list of conditions and the following disclaimer.
37 * 2. Redistributions in binary form must reproduce the above copyright
38 * notice, this list of conditions and the following disclaimer in the
39 * documentation and/or other materials provided with the distribution.
40 * 4. Neither the name of the University nor the names of its contributors
41 * may be used to endorse or promote products derived from this software
42 * without specific prior written permission.
43 *
44 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
45 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
46 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
47 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
48 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
49 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
50 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
51 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
52 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
53 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
54 * SUCH DAMAGE.
55 */
56
57#include <ctype.h>
58#include <errno.h>
59#include <netdb.h>
60#include <stdio.h>
61#include <stdlib.h>
62#include <string.h>
63#include <stdint.h>
64#include <stddef.h>
65
66#include "nsswitch.h"
67#include <arpa/inet.h>
68#include <arpa/nameser.h>
69#include <nss_dns.h>
70#include <resolv/resolv-internal.h>
71#include <resolv/resolv_context.h>
72
73/* Maximum number of aliases we allow. */
74#define MAX_NR_ALIASES 48
75
76
77#if PACKETSZ > 65536
78# define MAXPACKET PACKETSZ
79#else
80# define MAXPACKET 65536
81#endif
82
83
84typedef enum
85{
86 BYADDR,
87 BYNAME
88} lookup_method;
89
90
91/* We need this time later. */
92typedef union querybuf
93{
94 HEADER hdr;
95 u_char buf[MAXPACKET];
96} querybuf;
97
98/* Prototypes for local functions. */
99static enum nss_status getanswer_r (const querybuf *answer, int anslen,
100 struct netent *result, char *buffer,
101 size_t buflen, int *errnop, int *h_errnop,
102 lookup_method net_i);
103
104
105enum nss_status
106_nss_dns_getnetbyname_r (const char *name, struct netent *result,
107 char *buffer, size_t buflen, int *errnop,
108 int *herrnop)
109{
110 /* Return entry for network with NAME. */
111 union
112 {
113 querybuf *buf;
114 u_char *ptr;
115 } net_buffer;
116 querybuf *orig_net_buffer;
117 int anslen;
118 enum nss_status status;
119
120 struct resolv_context *ctx = __resolv_context_get ();
121 if (ctx == NULL)
122 {
123 *errnop = errno;
124 *herrnop = NETDB_INTERNAL;
125 return NSS_STATUS_UNAVAIL;
126 }
127
128 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
129
130 anslen = __res_context_search
131 (ctx, name, C_IN, T_PTR, net_buffer.buf->buf,
132 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
133 if (anslen < 0)
134 {
135 /* Nothing found. */
136 *errnop = errno;
137 if (net_buffer.buf != orig_net_buffer)
138 free (net_buffer.buf);
139 __resolv_context_put (ctx);
140 return (errno == ECONNREFUSED
141 || errno == EPFNOSUPPORT
142 || errno == EAFNOSUPPORT)
143 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
144 }
145
146 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
147 errnop, herrnop, BYNAME);
148 if (net_buffer.buf != orig_net_buffer)
149 free (net_buffer.buf);
150 __resolv_context_put (ctx);
151 return status;
152}
153libc_hidden_def (_nss_dns_getnetbyname_r)
154
155enum nss_status
156_nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
157 char *buffer, size_t buflen, int *errnop,
158 int *herrnop)
159{
160 /* Return entry for network with NAME. */
161 enum nss_status status;
162 union
163 {
164 querybuf *buf;
165 u_char *ptr;
166 } net_buffer;
167 querybuf *orig_net_buffer;
168 unsigned int net_bytes[4];
169 char qbuf[MAXDNAME];
170 int cnt, anslen;
171 uint32_t net2;
172 int olderr = errno;
173
174 /* No net address lookup for IPv6 yet. */
175 if (type != AF_INET)
176 return NSS_STATUS_UNAVAIL;
177
178 struct resolv_context *ctx = __resolv_context_get ();
179 if (ctx == NULL)
180 {
181 *errnop = errno;
182 *herrnop = NETDB_INTERNAL;
183 return NSS_STATUS_UNAVAIL;
184 }
185
186 net2 = (uint32_t) net;
187 for (cnt = 4; net2 != 0; net2 >>= 8)
188 net_bytes[--cnt] = net2 & 0xff;
189
190 switch (cnt)
191 {
192 case 3:
193 /* Class A network. */
194 sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
195 break;
196 case 2:
197 /* Class B network. */
198 sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
199 break;
200 case 1:
201 /* Class C network. */
202 sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
203 net_bytes[1]);
204 break;
205 case 0:
206 /* Class D - E network. */
207 sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
208 net_bytes[1], net_bytes[0]);
209 break;
210 }
211
212 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
213
214 anslen = __res_context_query (ctx, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
215 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
216 if (anslen < 0)
217 {
218 /* Nothing found. */
219 int err = errno;
220 __set_errno (olderr);
221 if (net_buffer.buf != orig_net_buffer)
222 free (net_buffer.buf);
223 __resolv_context_put (ctx);
224 return (err == ECONNREFUSED
225 || err == EPFNOSUPPORT
226 || err == EAFNOSUPPORT)
227 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
228 }
229
230 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
231 errnop, herrnop, BYADDR);
232 if (net_buffer.buf != orig_net_buffer)
233 free (net_buffer.buf);
234 if (status == NSS_STATUS_SUCCESS)
235 {
236 /* Strip trailing zeros. */
237 unsigned int u_net = net; /* Maybe net should be unsigned? */
238
239 while ((u_net & 0xff) == 0 && u_net != 0)
240 u_net >>= 8;
241 result->n_net = u_net;
242 }
243
244 __resolv_context_put (ctx);
245 return status;
246}
247libc_hidden_def (_nss_dns_getnetbyaddr_r)
248
249static enum nss_status
250getanswer_r (const querybuf *answer, int anslen, struct netent *result,
251 char *buffer, size_t buflen, int *errnop, int *h_errnop,
252 lookup_method net_i)
253{
254 /*
255 * Find first satisfactory answer
256 *
257 * answer --> +------------+ ( MESSAGE )
258 * | Header |
259 * +------------+
260 * | Question | the question for the name server
261 * +------------+
262 * | Answer | RRs answering the question
263 * +------------+
264 * | Authority | RRs pointing toward an authority
265 * | Additional | RRs holding additional information
266 * +------------+
267 */
268 struct net_data
269 {
270 char *aliases[MAX_NR_ALIASES];
271 char linebuffer[0];
272 } *net_data;
273
274 uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
275 buffer += pad;
276
277 if (__glibc_unlikely (buflen < sizeof (*net_data) + pad))
278 {
279 /* The buffer is too small. */
280 too_small:
281 *errnop = ERANGE;
282 *h_errnop = NETDB_INTERNAL;
283 return NSS_STATUS_TRYAGAIN;
284 }
285 buflen -= pad;
286
287 net_data = (struct net_data *) buffer;
288 int linebuflen = buflen - offsetof (struct net_data, linebuffer);
289 if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
290 linebuflen = INT_MAX;
291 const unsigned char *end_of_message = &answer->buf[anslen];
292 const HEADER *header_pointer = &answer->hdr;
293 /* #/records in the answer section. */
294 int answer_count = ntohs (header_pointer->ancount);
295 /* #/entries in the question section. */
296 int question_count = ntohs (header_pointer->qdcount);
297 char *bp = net_data->linebuffer;
298 const unsigned char *cp = &answer->buf[HFIXEDSZ];
299 char **alias_pointer;
300 int have_answer;
301 u_char packtmp[NS_MAXCDNAME];
302
303 if (question_count == 0)
304 {
305 /* FIXME: the Sun version uses for host name lookup an additional
306 parameter for pointing to h_errno. this is missing here.
307 OSF/1 has a per-thread h_errno variable. */
308 if (header_pointer->aa != 0)
309 {
310 __set_h_errno (HOST_NOT_FOUND);
311 return NSS_STATUS_NOTFOUND;
312 }
313 else
314 {
315 __set_h_errno (TRY_AGAIN);
316 return NSS_STATUS_TRYAGAIN;
317 }
318 }
319
320 /* Skip the question part. */
321 while (question_count-- > 0)
322 {
323 int n = __libc_dn_skipname (cp, end_of_message);
324 if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
325 {
326 __set_h_errno (NO_RECOVERY);
327 return NSS_STATUS_UNAVAIL;
328 }
329 cp += n + QFIXEDSZ;
330 }
331
332 alias_pointer = result->n_aliases = &net_data->aliases[0];
333 *alias_pointer = NULL;
334 have_answer = 0;
335
336 while (--answer_count >= 0 && cp < end_of_message)
337 {
338 int n = __ns_name_unpack (answer->buf, end_of_message, cp,
339 packtmp, sizeof packtmp);
340 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
341 {
342 if (errno == EMSGSIZE)
343 goto too_small;
344
345 n = -1;
346 }
347
348 if (n < 0 || __libc_res_dnok (bp) == 0)
349 break;
350 cp += n;
351
352 if (end_of_message - cp < 10)
353 {
354 __set_h_errno (NO_RECOVERY);
355 return NSS_STATUS_UNAVAIL;
356 }
357
358 int type, class;
359 GETSHORT (type, cp);
360 GETSHORT (class, cp);
361 cp += INT32SZ; /* TTL */
362 uint16_t rdatalen;
363 GETSHORT (rdatalen, cp);
364 if (end_of_message - cp < rdatalen)
365 {
366 __set_h_errno (NO_RECOVERY);
367 return NSS_STATUS_UNAVAIL;
368 }
369
370 if (class == C_IN && type == T_PTR)
371 {
372 n = __ns_name_unpack (answer->buf, end_of_message, cp,
373 packtmp, sizeof packtmp);
374 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
375 {
376 if (errno == EMSGSIZE)
377 goto too_small;
378
379 n = -1;
380 }
381
382 if (n < 0 || !__libc_res_hnok (bp))
383 {
384 /* XXX What does this mean? The original form from bind
385 returns NULL. Incrementing cp has no effect in any case.
386 What should I return here. ??? */
387 cp += n;
388 return NSS_STATUS_UNAVAIL;
389 }
390 cp += rdatalen;
391 if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
392 {
393 *alias_pointer++ = bp;
394 n = strlen (bp) + 1;
395 bp += n;
396 linebuflen -= n;
397 result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
398 ++have_answer;
399 }
400 }
401 else
402 /* Skip over unknown record data. */
403 cp += rdatalen;
404 }
405
406 if (have_answer)
407 {
408 *alias_pointer = NULL;
409 switch (net_i)
410 {
411 case BYADDR:
412 result->n_name = *result->n_aliases++;
413 result->n_net = 0L;
414 return NSS_STATUS_SUCCESS;
415
416 case BYNAME:
417 {
418 char **ap;
419 for (ap = result->n_aliases; *ap != NULL; ++ap)
420 {
421 /* Check each alias name for being of the forms:
422 4.3.2.1.in-addr.arpa = net 1.2.3.4
423 3.2.1.in-addr.arpa = net 0.1.2.3
424 2.1.in-addr.arpa = net 0.0.1.2
425 1.in-addr.arpa = net 0.0.0.1
426 */
427 uint32_t val = 0; /* Accumulator for n_net value. */
428 unsigned int shift = 0; /* Which part we are parsing now. */
429 const char *p = *ap; /* Consuming the string. */
430 do
431 {
432 /* Match the leading 0 or 0[xX] base indicator. */
433 unsigned int base = 10;
434 if (*p == '0' && p[1] != '.')
435 {
436 base = 8;
437 ++p;
438 if (*p == 'x' || *p == 'X')
439 {
440 base = 16;
441 ++p;
442 if (*p == '.')
443 break; /* No digit here. Give up on alias. */
444 }
445 if (*p == '\0')
446 break;
447 }
448
449 uint32_t part = 0; /* Accumulates this part's number. */
450 do
451 {
452 if (isdigit (*p) && (*p - '0' < base))
453 part = (part * base) + (*p - '0');
454 else if (base == 16 && isxdigit (*p))
455 part = (part << 4) + 10 + (tolower (*p) - 'a');
456 ++p;
457 } while (*p != '\0' && *p != '.');
458
459 if (*p != '.')
460 break; /* Bad form. Give up on this name. */
461
462 /* Install this as the next more significant byte. */
463 val |= part << shift;
464 shift += 8;
465 ++p;
466
467 /* If we are out of digits now, there are two cases:
468 1. We are done with digits and now see "in-addr.arpa".
469 2. This is not the droid we are looking for. */
470 if (!isdigit (*p) && !__strcasecmp (p, "in-addr.arpa"))
471 {
472 result->n_net = val;
473 return NSS_STATUS_SUCCESS;
474 }
475
476 /* Keep going when we have seen fewer than 4 parts. */
477 } while (shift < 32);
478 }
479 }
480 break;
481 }
482 }
483
484 __set_h_errno (TRY_AGAIN);
485 return NSS_STATUS_TRYAGAIN;
486}
487

source code of glibc/resolv/nss_dns/dns-network.c