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 <nss_dns.h>
71#include <resolv/resolv-internal.h>
72#include <resolv/resolv_context.h>
73
74/* Maximum number of aliases we allow. */
75#define MAX_NR_ALIASES 48
76
77
78#if PACKETSZ > 65536
79# define MAXPACKET PACKETSZ
80#else
81# define MAXPACKET 65536
82#endif
83
84
85typedef enum
86{
87 BYADDR,
88 BYNAME
89} lookup_method;
90
91
92/* We need this time later. */
93typedef union querybuf
94{
95 HEADER hdr;
96 u_char buf[MAXPACKET];
97} querybuf;
98
99/* Prototypes for local functions. */
100static enum nss_status getanswer_r (const querybuf *answer, int anslen,
101 struct netent *result, char *buffer,
102 size_t buflen, int *errnop, int *h_errnop,
103 lookup_method net_i);
104
105
106enum nss_status
107_nss_dns_getnetbyname_r (const char *name, struct netent *result,
108 char *buffer, size_t buflen, int *errnop,
109 int *herrnop)
110{
111 /* Return entry for network with NAME. */
112 union
113 {
114 querybuf *buf;
115 u_char *ptr;
116 } net_buffer;
117 querybuf *orig_net_buffer;
118 int anslen;
119 enum nss_status status;
120
121 struct resolv_context *ctx = __resolv_context_get ();
122 if (ctx == NULL)
123 {
124 *errnop = errno;
125 *herrnop = NETDB_INTERNAL;
126 return NSS_STATUS_UNAVAIL;
127 }
128
129 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
130
131 anslen = __res_context_search
132 (ctx, name, C_IN, T_PTR, net_buffer.buf->buf,
133 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
134 if (anslen < 0)
135 {
136 /* Nothing found. */
137 *errnop = errno;
138 if (net_buffer.buf != orig_net_buffer)
139 free (net_buffer.buf);
140 __resolv_context_put (ctx);
141 return (errno == ECONNREFUSED
142 || errno == EPFNOSUPPORT
143 || errno == EAFNOSUPPORT)
144 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
145 }
146
147 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
148 errnop, herrnop, BYNAME);
149 if (net_buffer.buf != orig_net_buffer)
150 free (net_buffer.buf);
151 __resolv_context_put (ctx);
152 return status;
153}
154libc_hidden_def (_nss_dns_getnetbyname_r)
155
156enum nss_status
157_nss_dns_getnetbyaddr_r (uint32_t net, int type, struct netent *result,
158 char *buffer, size_t buflen, int *errnop,
159 int *herrnop)
160{
161 /* Return entry for network with NAME. */
162 enum nss_status status;
163 union
164 {
165 querybuf *buf;
166 u_char *ptr;
167 } net_buffer;
168 querybuf *orig_net_buffer;
169 unsigned int net_bytes[4];
170 char qbuf[MAXDNAME];
171 int cnt, anslen;
172 uint32_t net2;
173 int olderr = errno;
174
175 /* No net address lookup for IPv6 yet. */
176 if (type != AF_INET)
177 return NSS_STATUS_UNAVAIL;
178
179 struct resolv_context *ctx = __resolv_context_get ();
180 if (ctx == NULL)
181 {
182 *errnop = errno;
183 *herrnop = NETDB_INTERNAL;
184 return NSS_STATUS_UNAVAIL;
185 }
186
187 net2 = (uint32_t) net;
188 for (cnt = 4; net2 != 0; net2 >>= 8)
189 net_bytes[--cnt] = net2 & 0xff;
190
191 switch (cnt)
192 {
193 case 3:
194 /* Class A network. */
195 sprintf (qbuf, "0.0.0.%u.in-addr.arpa", net_bytes[3]);
196 break;
197 case 2:
198 /* Class B network. */
199 sprintf (qbuf, "0.0.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2]);
200 break;
201 case 1:
202 /* Class C network. */
203 sprintf (qbuf, "0.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
204 net_bytes[1]);
205 break;
206 case 0:
207 /* Class D - E network. */
208 sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", net_bytes[3], net_bytes[2],
209 net_bytes[1], net_bytes[0]);
210 break;
211 }
212
213 net_buffer.buf = orig_net_buffer = (querybuf *) alloca (1024);
214
215 anslen = __res_context_query (ctx, qbuf, C_IN, T_PTR, net_buffer.buf->buf,
216 1024, &net_buffer.ptr, NULL, NULL, NULL, NULL);
217 if (anslen < 0)
218 {
219 /* Nothing found. */
220 int err = errno;
221 __set_errno (olderr);
222 if (net_buffer.buf != orig_net_buffer)
223 free (net_buffer.buf);
224 __resolv_context_put (ctx);
225 return (err == ECONNREFUSED
226 || err == EPFNOSUPPORT
227 || err == EAFNOSUPPORT)
228 ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
229 }
230
231 status = getanswer_r (net_buffer.buf, anslen, result, buffer, buflen,
232 errnop, herrnop, BYADDR);
233 if (net_buffer.buf != orig_net_buffer)
234 free (net_buffer.buf);
235 if (status == NSS_STATUS_SUCCESS)
236 {
237 /* Strip trailing zeros. */
238 unsigned int u_net = net; /* Maybe net should be unsigned? */
239
240 while ((u_net & 0xff) == 0 && u_net != 0)
241 u_net >>= 8;
242 result->n_net = u_net;
243 }
244
245 __resolv_context_put (ctx);
246 return status;
247}
248libc_hidden_def (_nss_dns_getnetbyaddr_r)
249
250static enum nss_status
251getanswer_r (const querybuf *answer, int anslen, struct netent *result,
252 char *buffer, size_t buflen, int *errnop, int *h_errnop,
253 lookup_method net_i)
254{
255 /*
256 * Find first satisfactory answer
257 *
258 * answer --> +------------+ ( MESSAGE )
259 * | Header |
260 * +------------+
261 * | Question | the question for the name server
262 * +------------+
263 * | Answer | RRs answering the question
264 * +------------+
265 * | Authority | RRs pointing toward an authority
266 * | Additional | RRs holding additional information
267 * +------------+
268 */
269 struct net_data
270 {
271 char *aliases[MAX_NR_ALIASES];
272 char linebuffer[0];
273 } *net_data;
274
275 uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct net_data);
276 buffer += pad;
277
278 if (__glibc_unlikely (buflen < sizeof (*net_data) + pad))
279 {
280 /* The buffer is too small. */
281 too_small:
282 *errnop = ERANGE;
283 *h_errnop = NETDB_INTERNAL;
284 return NSS_STATUS_TRYAGAIN;
285 }
286 buflen -= pad;
287
288 net_data = (struct net_data *) buffer;
289 int linebuflen = buflen - offsetof (struct net_data, linebuffer);
290 if (buflen - offsetof (struct net_data, linebuffer) != linebuflen)
291 linebuflen = INT_MAX;
292 const unsigned char *end_of_message = &answer->buf[anslen];
293 const HEADER *header_pointer = &answer->hdr;
294 /* #/records in the answer section. */
295 int answer_count = ntohs (header_pointer->ancount);
296 /* #/entries in the question section. */
297 int question_count = ntohs (header_pointer->qdcount);
298 char *bp = net_data->linebuffer;
299 const unsigned char *cp = &answer->buf[HFIXEDSZ];
300 char **alias_pointer;
301 int have_answer;
302 u_char packtmp[NS_MAXCDNAME];
303
304 if (question_count == 0)
305 {
306 /* FIXME: the Sun version uses for host name lookup an additional
307 parameter for pointing to h_errno. this is missing here.
308 OSF/1 has a per-thread h_errno variable. */
309 if (header_pointer->aa != 0)
310 {
311 __set_h_errno (HOST_NOT_FOUND);
312 return NSS_STATUS_NOTFOUND;
313 }
314 else
315 {
316 __set_h_errno (TRY_AGAIN);
317 return NSS_STATUS_TRYAGAIN;
318 }
319 }
320
321 /* Skip the question part. */
322 while (question_count-- > 0)
323 {
324 int n = __libc_dn_skipname (cp, end_of_message);
325 if (n < 0 || end_of_message - (cp + n) < QFIXEDSZ)
326 {
327 __set_h_errno (NO_RECOVERY);
328 return NSS_STATUS_UNAVAIL;
329 }
330 cp += n + QFIXEDSZ;
331 }
332
333 alias_pointer = result->n_aliases = &net_data->aliases[0];
334 *alias_pointer = NULL;
335 have_answer = 0;
336
337 while (--answer_count >= 0 && cp < end_of_message)
338 {
339 int n = __ns_name_unpack (answer->buf, end_of_message, cp,
340 packtmp, sizeof packtmp);
341 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
342 {
343 if (errno == EMSGSIZE)
344 goto too_small;
345
346 n = -1;
347 }
348
349 if (n < 0 || __libc_res_dnok (bp) == 0)
350 break;
351 cp += n;
352
353 if (end_of_message - cp < 10)
354 {
355 __set_h_errno (NO_RECOVERY);
356 return NSS_STATUS_UNAVAIL;
357 }
358
359 int type, class;
360 GETSHORT (type, cp);
361 GETSHORT (class, cp);
362 cp += INT32SZ; /* TTL */
363 uint16_t rdatalen;
364 GETSHORT (rdatalen, cp);
365 if (end_of_message - cp < rdatalen)
366 {
367 __set_h_errno (NO_RECOVERY);
368 return NSS_STATUS_UNAVAIL;
369 }
370
371 if (class == C_IN && type == T_PTR)
372 {
373 n = __ns_name_unpack (answer->buf, end_of_message, cp,
374 packtmp, sizeof packtmp);
375 if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
376 {
377 if (errno == EMSGSIZE)
378 goto too_small;
379
380 n = -1;
381 }
382
383 if (n < 0 || !__libc_res_hnok (bp))
384 {
385 /* XXX What does this mean? The original form from bind
386 returns NULL. Incrementing cp has no effect in any case.
387 What should I return here. ??? */
388 cp += n;
389 return NSS_STATUS_UNAVAIL;
390 }
391 cp += rdatalen;
392 if (alias_pointer + 2 < &net_data->aliases[MAX_NR_ALIASES])
393 {
394 *alias_pointer++ = bp;
395 n = strlen (bp) + 1;
396 bp += n;
397 linebuflen -= n;
398 result->n_addrtype = class == C_IN ? AF_INET : AF_UNSPEC;
399 ++have_answer;
400 }
401 }
402 else
403 /* Skip over unknown record data. */
404 cp += rdatalen;
405 }
406
407 if (have_answer)
408 {
409 *alias_pointer = NULL;
410 switch (net_i)
411 {
412 case BYADDR:
413 result->n_name = *result->n_aliases++;
414 result->n_net = 0L;
415 return NSS_STATUS_SUCCESS;
416
417 case BYNAME:
418 {
419 char **ap;
420 for (ap = result->n_aliases; *ap != NULL; ++ap)
421 {
422 /* Check each alias name for being of the forms:
423 4.3.2.1.in-addr.arpa = net 1.2.3.4
424 3.2.1.in-addr.arpa = net 0.1.2.3
425 2.1.in-addr.arpa = net 0.0.1.2
426 1.in-addr.arpa = net 0.0.0.1
427 */
428 uint32_t val = 0; /* Accumulator for n_net value. */
429 unsigned int shift = 0; /* Which part we are parsing now. */
430 const char *p = *ap; /* Consuming the string. */
431 do
432 {
433 /* Match the leading 0 or 0[xX] base indicator. */
434 unsigned int base = 10;
435 if (*p == '0' && p[1] != '.')
436 {
437 base = 8;
438 ++p;
439 if (*p == 'x' || *p == 'X')
440 {
441 base = 16;
442 ++p;
443 if (*p == '.')
444 break; /* No digit here. Give up on alias. */
445 }
446 if (*p == '\0')
447 break;
448 }
449
450 uint32_t part = 0; /* Accumulates this part's number. */
451 do
452 {
453 if (isdigit (*p) && (*p - '0' < base))
454 part = (part * base) + (*p - '0');
455 else if (base == 16 && isxdigit (*p))
456 part = (part << 4) + 10 + (tolower (*p) - 'a');
457 ++p;
458 } while (*p != '\0' && *p != '.');
459
460 if (*p != '.')
461 break; /* Bad form. Give up on this name. */
462
463 /* Install this as the next more significant byte. */
464 val |= part << shift;
465 shift += 8;
466 ++p;
467
468 /* If we are out of digits now, there are two cases:
469 1. We are done with digits and now see "in-addr.arpa".
470 2. This is not the droid we are looking for. */
471 if (!isdigit (*p) && !__strcasecmp (p, "in-addr.arpa"))
472 {
473 result->n_net = val;
474 return NSS_STATUS_SUCCESS;
475 }
476
477 /* Keep going when we have seen fewer than 4 parts. */
478 } while (shift < 32);
479 }
480 }
481 break;
482 }
483 }
484
485 __set_h_errno (TRY_AGAIN);
486 return NSS_STATUS_TRYAGAIN;
487}
488