1/* Resolver state initialization and resolv.conf parsing.
2 Copyright (C) 1995-2017 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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 <http://www.gnu.org/licenses/>. */
18
19/*
20 * Copyright (c) 1985, 1989, 1993
21 * The Regents of the University of California. All rights reserved.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the above copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 4. Neither the name of the University nor the names of its contributors
32 * may be used to endorse or promote products derived from this software
33 * without specific prior written permission.
34 *
35 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
36 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
38 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
39 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
40 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
41 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
43 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
44 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
45 * SUCH DAMAGE.
46 */
47
48/*
49 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
50 *
51 * Permission to use, copy, modify, and distribute this software for any
52 * purpose with or without fee is hereby granted, provided that the above
53 * copyright notice and this permission notice appear in all copies, and that
54 * the name of Digital Equipment Corporation not be used in advertising or
55 * publicity pertaining to distribution of the document or software without
56 * specific, written prior permission.
57 *
58 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
59 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
60 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
61 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
62 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
63 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
64 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
65 * SOFTWARE.
66 */
67
68/*
69 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
70 *
71 * Permission to use, copy, modify, and distribute this software for any
72 * purpose with or without fee is hereby granted, provided that the above
73 * copyright notice and this permission notice appear in all copies.
74 *
75 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
76 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
77 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
78 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
79 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
80 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
81 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
82 * SOFTWARE.
83 */
84
85#include <ctype.h>
86#include <netdb.h>
87#include <resolv/resolv-internal.h>
88#include <res_hconf.h>
89#include <stdio.h>
90#include <stdio_ext.h>
91#include <stdlib.h>
92#include <string.h>
93#include <unistd.h>
94#include <stdint.h>
95#include <arpa/inet.h>
96#include <arpa/nameser.h>
97#include <net/if.h>
98#include <netinet/in.h>
99#include <sys/param.h>
100#include <sys/socket.h>
101#include <sys/time.h>
102#include <sys/types.h>
103#include <inet/net-internal.h>
104#include <errno.h>
105#include <resolv_conf.h>
106
107static uint32_t net_mask (struct in_addr);
108
109int
110res_ninit (res_state statp)
111{
112 return __res_vinit (statp, 0);
113}
114libc_hidden_def (__res_ninit)
115
116/* Return true if CH separates the netmask in the "sortlist"
117 directive. */
118static inline bool
119is_sort_mask (char ch)
120{
121 return ch == '/' || ch == '&';
122}
123
124/* Array of name server addresses. */
125#define DYNARRAY_STRUCT nameserver_list
126#define DYNARRAY_ELEMENT const struct sockaddr *
127#define DYNARRAY_ELEMENT_FREE(e) free ((struct sockaddr *) *(e))
128#define DYNARRAY_INITIAL_SIZE 3
129#define DYNARRAY_PREFIX nameserver_list_
130#include <malloc/dynarray-skeleton.c>
131
132/* Array of strings for the search array. The backing store is
133 managed separately. */
134#define DYNARRAY_STRUCT search_list
135#define DYNARRAY_ELEMENT const char *
136#define DYNARRAY_INITIAL_SIZE 6
137#define DYNARRAY_PREFIX search_list_
138#include <malloc/dynarray-skeleton.c>
139
140/* Array of name server addresses. */
141#define DYNARRAY_STRUCT sort_list
142#define DYNARRAY_ELEMENT struct resolv_sortlist_entry
143#define DYNARRAY_INITIAL_SIZE 0
144#define DYNARRAY_PREFIX sort_list_
145#include <malloc/dynarray-skeleton.c>
146
147/* resolv.conf parser state and results. */
148struct resolv_conf_parser
149{
150 char *buffer; /* Temporary buffer for reading lines. */
151
152 struct nameserver_list nameserver_list; /* Nameserver addresses. */
153
154 char *search_list_store; /* Backing storage for search list entries. */
155 struct search_list search_list; /* Points into search_list_store. */
156
157 struct sort_list sort_list; /* Address preference sorting list. */
158
159 /* Configuration template. The non-array elements are filled in
160 directly. The array elements are updated prior to the call to
161 __resolv_conf_attach. */
162 struct resolv_conf template;
163};
164
165/* Return true if *PREINIT contains actual preinitialization. */
166static bool
167has_preinit_values (const struct __res_state *preinit)
168{
169 return (preinit->retrans != 0 && preinit->retrans != RES_TIMEOUT)
170 || (preinit->retry != 0 && preinit->retry != RES_DFLRETRY)
171 || (preinit->options != 0
172 && (preinit->options & ~RES_INIT) != RES_DEFAULT);
173}
174
175static void
176resolv_conf_parser_init (struct resolv_conf_parser *parser,
177 const struct __res_state *preinit)
178{
179 parser->buffer = NULL;
180 parser->search_list_store = NULL;
181 nameserver_list_init (&parser->nameserver_list);
182 search_list_init (&parser->search_list);
183 sort_list_init (&parser->sort_list);
184
185 if (preinit != NULL)
186 {
187 parser->template.retrans = preinit->retrans;
188 parser->template.retry = preinit->retry;
189 parser->template.options = preinit->options | RES_INIT;
190 }
191 else
192 {
193 parser->template.retrans = RES_TIMEOUT;
194 parser->template.retry = RES_DFLRETRY;
195 parser->template.options = RES_DEFAULT | RES_INIT;
196 }
197 parser->template.ndots = 1;
198}
199
200static void
201resolv_conf_parser_free (struct resolv_conf_parser *parser)
202{
203 free (parser->buffer);
204 free (parser->search_list_store);
205 nameserver_list_free (&parser->nameserver_list);
206 search_list_free (&parser->search_list);
207 sort_list_free (&parser->sort_list);
208}
209
210/* Allocate a struct sockaddr_in object on the heap, with the
211 specified address and port. */
212static struct sockaddr *
213allocate_address_v4 (struct in_addr a, uint16_t port)
214{
215 struct sockaddr_in *sa4 = malloc (sizeof (*sa4));
216 if (sa4 == NULL)
217 return NULL;
218 sa4->sin_family = AF_INET;
219 sa4->sin_addr = a;
220 sa4->sin_port = htons (port);
221 return (struct sockaddr *) sa4;
222}
223
224/* Try to obtain the domain name from the host name and store it in
225 *RESULT. Return false on memory allocation failure. If the domain
226 name cannot be determined for any other reason, write NULL to
227 *RESULT and return true. */
228static bool
229domain_from_hostname (char **result)
230{
231 char buf[256];
232 /* gethostbyname may not terminate the buffer. */
233 buf[sizeof (buf) - 1] = '\0';
234 if (__gethostname (buf, sizeof (buf) - 1) == 0)
235 {
236 char *dot = strchr (buf, '.');
237 if (dot != NULL)
238 {
239 *result = __strdup (dot + 1);
240 if (*result == NULL)
241 return false;
242 return true;
243 }
244 }
245 *result = NULL;
246 return true;
247}
248
249static void res_setoptions (struct resolv_conf_parser *, const char *options);
250
251/* Internal helper function for __res_vinit, to aid with resource
252 deallocation and error handling. Return true on success, false on
253 failure. */
254static bool
255res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
256{
257 char *cp;
258 size_t buffer_size = 0;
259 bool haveenv = false;
260
261 /* Allow user to override the local domain definition. */
262 if ((cp = getenv ("LOCALDOMAIN")) != NULL)
263 {
264 /* The code below splits the string in place. */
265 cp = __strdup (cp);
266 if (cp == NULL)
267 return false;
268 free (parser->search_list_store);
269 parser->search_list_store = cp;
270 haveenv = true;
271
272 /* The string will be truncated as needed below. */
273 search_list_add (&parser->search_list, cp);
274
275 /* Set search list to be blank-separated strings from rest of
276 env value. Permits users of LOCALDOMAIN to still have a
277 search list, and anyone to set the one that they want to use
278 as an individual (even more important now that the rfc1535
279 stuff restricts searches). */
280 for (bool in_name = true; *cp != '\0'; cp++)
281 {
282 if (*cp == '\n')
283 {
284 *cp = '\0';
285 break;
286 }
287 else if (*cp == ' ' || *cp == '\t')
288 {
289 *cp = '\0';
290 in_name = false;
291 }
292 else if (!in_name)
293 {
294 search_list_add (&parser->search_list, cp);
295 in_name = true;
296 }
297 }
298 }
299
300#define MATCH(line, name) \
301 (!strncmp ((line), name, sizeof (name) - 1) \
302 && ((line)[sizeof (name) - 1] == ' ' \
303 || (line)[sizeof (name) - 1] == '\t'))
304
305 if (fp != NULL)
306 {
307 /* No threads use this stream. */
308 __fsetlocking (fp, FSETLOCKING_BYCALLER);
309 /* Read the config file. */
310 while (true)
311 {
312 {
313 ssize_t ret = __getline (&parser->buffer, &buffer_size, fp);
314 if (ret <= 0)
315 {
316 if (_IO_ferror_unlocked (fp))
317 return false;
318 else
319 break;
320 }
321 }
322
323 /* Skip comments. */
324 if (*parser->buffer == ';' || *parser->buffer == '#')
325 continue;
326 /* Read default domain name. */
327 if (MATCH (parser->buffer, "domain"))
328 {
329 if (haveenv)
330 /* LOCALDOMAIN overrides the configuration file. */
331 continue;
332 cp = parser->buffer + sizeof ("domain") - 1;
333 while (*cp == ' ' || *cp == '\t')
334 cp++;
335 if ((*cp == '\0') || (*cp == '\n'))
336 continue;
337
338 cp = __strdup (cp);
339 if (cp == NULL)
340 return false;
341 free (parser->search_list_store);
342 parser->search_list_store = cp;
343 search_list_clear (&parser->search_list);
344 search_list_add (&parser->search_list, cp);
345 /* Replace trailing whitespace. */
346 if ((cp = strpbrk (cp, " \t\n")) != NULL)
347 *cp = '\0';
348 continue;
349 }
350 /* Set search list. */
351 if (MATCH (parser->buffer, "search"))
352 {
353 if (haveenv)
354 /* LOCALDOMAIN overrides the configuration file. */
355 continue;
356 cp = parser->buffer + sizeof ("search") - 1;
357 while (*cp == ' ' || *cp == '\t')
358 cp++;
359 if ((*cp == '\0') || (*cp == '\n'))
360 continue;
361
362 {
363 char *p = strchr (cp, '\n');
364 if (p != NULL)
365 *p = '\0';
366 }
367 cp = __strdup (cp);
368 if (cp == NULL)
369 return false;
370 free (parser->search_list_store);
371 parser->search_list_store = cp;
372
373 /* The string is truncated below. */
374 search_list_clear (&parser->search_list);
375 search_list_add (&parser->search_list, cp);
376
377 /* Set search list to be blank-separated strings on rest
378 of line. */
379 for (bool in_name = true; *cp != '\0'; cp++)
380 {
381 if (*cp == ' ' || *cp == '\t')
382 {
383 *cp = '\0';
384 in_name = false;
385 }
386 else if (!in_name)
387 {
388 search_list_add (&parser->search_list, cp);
389 in_name = true;
390 }
391 }
392 continue;
393 }
394 /* Read nameservers to query. */
395 if (MATCH (parser->buffer, "nameserver"))
396 {
397 struct in_addr a;
398
399 cp = parser->buffer + sizeof ("nameserver") - 1;
400 while (*cp == ' ' || *cp == '\t')
401 cp++;
402 struct sockaddr *sa;
403 if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
404 {
405 sa = allocate_address_v4 (a, NAMESERVER_PORT);
406 if (sa == NULL)
407 return false;
408 }
409 else
410 {
411 struct in6_addr a6;
412 char *el;
413
414 if ((el = strpbrk (cp, " \t\n")) != NULL)
415 *el = '\0';
416 if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
417 *el = '\0';
418 if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
419 {
420 struct sockaddr_in6 *sa6;
421
422 sa6 = malloc (sizeof (*sa6));
423 if (sa6 == NULL)
424 return false;
425
426 sa6->sin6_family = AF_INET6;
427 sa6->sin6_port = htons (NAMESERVER_PORT);
428 sa6->sin6_flowinfo = 0;
429 sa6->sin6_addr = a6;
430
431 sa6->sin6_scope_id = 0;
432 if (__glibc_likely (el != NULL))
433 /* Ignore errors, for backwards
434 compatibility. */
435 __inet6_scopeid_pton
436 (&a6, el + 1, &sa6->sin6_scope_id);
437 sa = (struct sockaddr *) sa6;
438 }
439 else
440 /* IPv6 address parse failure. */
441 sa = NULL;
442 }
443 if (sa != NULL)
444 {
445 const struct sockaddr **p = nameserver_list_emplace
446 (&parser->nameserver_list);
447 if (p != NULL)
448 *p = sa;
449 }
450 continue;
451 }
452 if (MATCH (parser->buffer, "sortlist"))
453 {
454 struct in_addr a;
455
456 cp = parser->buffer + sizeof ("sortlist") - 1;
457 while (true)
458 {
459 while (*cp == ' ' || *cp == '\t')
460 cp++;
461 if (*cp == '\0' || *cp == '\n' || *cp == ';')
462 break;
463 char *net = cp;
464 while (*cp && !is_sort_mask (*cp) && *cp != ';'
465 && isascii (*cp) && !isspace (*cp))
466 cp++;
467 char separator = *cp;
468 *cp = 0;
469 struct resolv_sortlist_entry e;
470 if (__inet_aton (net, &a))
471 {
472 e.addr = a;
473 if (is_sort_mask (separator))
474 {
475 *cp++ = separator;
476 net = cp;
477 while (*cp && *cp != ';'
478 && isascii (*cp) && !isspace (*cp))
479 cp++;
480 separator = *cp;
481 *cp = 0;
482 if (__inet_aton (net, &a))
483 e.mask = a.s_addr;
484 else
485 e.mask = net_mask (e.addr);
486 }
487 else
488 e.mask = net_mask (e.addr);
489 sort_list_add (&parser->sort_list, e);
490 }
491 *cp = separator;
492 }
493 continue;
494 }
495 if (MATCH (parser->buffer, "options"))
496 {
497 res_setoptions (parser, parser->buffer + sizeof ("options") - 1);
498 continue;
499 }
500 }
501 fclose (fp);
502 }
503 if (__glibc_unlikely (nameserver_list_size (&parser->nameserver_list) == 0))
504 {
505 const struct sockaddr **p
506 = nameserver_list_emplace (&parser->nameserver_list);
507 if (p == NULL)
508 return false;
509 *p = allocate_address_v4 (__inet_makeaddr (IN_LOOPBACKNET, 1),
510 NAMESERVER_PORT);
511 if (*p == NULL)
512 return false;
513 }
514
515 if (search_list_size (&parser->search_list) == 0)
516 {
517 char *domain;
518 if (!domain_from_hostname (&domain))
519 return false;
520 if (domain != NULL)
521 {
522 free (parser->search_list_store);
523 parser->search_list_store = domain;
524 search_list_add (&parser->search_list, domain);
525 }
526 }
527
528 if ((cp = getenv ("RES_OPTIONS")) != NULL)
529 res_setoptions (parser, cp);
530
531 if (nameserver_list_has_failed (&parser->nameserver_list)
532 || search_list_has_failed (&parser->search_list)
533 || sort_list_has_failed (&parser->sort_list))
534 {
535 __set_errno (ENOMEM);
536 return false;
537 }
538
539 return true;
540}
541
542struct resolv_conf *
543__resolv_conf_load (struct __res_state *preinit)
544{
545 /* Ensure that /etc/hosts.conf has been loaded (once). */
546 _res_hconf_init ();
547
548 FILE *fp = fopen (_PATH_RESCONF, "rce");
549 if (fp == NULL)
550 switch (errno)
551 {
552 case EACCES:
553 case EISDIR:
554 case ELOOP:
555 case ENOENT:
556 case ENOTDIR:
557 case EPERM:
558 /* Ignore these errors. They are persistent errors caused
559 by file system contents. */
560 break;
561 default:
562 /* Other errors refer to resource allocation problems and
563 need to be handled by the application. */
564 return NULL;
565 }
566
567 struct resolv_conf_parser parser;
568 resolv_conf_parser_init (&parser, preinit);
569
570 struct resolv_conf *conf = NULL;
571 if (res_vinit_1 (fp, &parser))
572 {
573 parser.template.nameserver_list
574 = nameserver_list_begin (&parser.nameserver_list);
575 parser.template.nameserver_list_size
576 = nameserver_list_size (&parser.nameserver_list);
577 parser.template.search_list = search_list_begin (&parser.search_list);
578 parser.template.search_list_size
579 = search_list_size (&parser.search_list);
580 parser.template.sort_list = sort_list_begin (&parser.sort_list);
581 parser.template.sort_list_size = sort_list_size (&parser.sort_list);
582 conf = __resolv_conf_allocate (&parser.template);
583 }
584 resolv_conf_parser_free (&parser);
585
586 return conf;
587}
588
589/* Set up default settings. If the /etc/resolv.conf configuration
590 file exist, the values there will have precedence. Otherwise, the
591 server address is set to INADDR_LOOPBACK and the default domain
592 name comes from gethostname. The RES_OPTIONS and LOCALDOMAIN
593 environment variables can be used to override some settings.
594 Return 0 if completes successfully, -1 on error. */
595int
596__res_vinit (res_state statp, int preinit)
597{
598 struct resolv_conf *conf;
599 if (preinit && has_preinit_values (statp))
600 /* For the preinit case, we cannot use the cached configuration
601 because some settings could be different. */
602 conf = __resolv_conf_load (statp);
603 else
604 conf = __resolv_conf_get_current ();
605 if (conf == NULL)
606 return -1;
607
608 bool ok = __resolv_conf_attach (statp, conf);
609 __resolv_conf_put (conf);
610 if (ok)
611 {
612 if (preinit)
613 statp->id = res_randomid ();
614 return 0;
615 }
616 else
617 return -1;
618}
619
620static void
621res_setoptions (struct resolv_conf_parser *parser, const char *options)
622{
623 const char *cp = options;
624
625 while (*cp)
626 {
627 /* Skip leading and inner runs of spaces. */
628 while (*cp == ' ' || *cp == '\t')
629 cp++;
630 /* Search for and process individual options. */
631 if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
632 {
633 int i = atoi (cp + sizeof ("ndots:") - 1);
634 if (i <= RES_MAXNDOTS)
635 parser->template.ndots = i;
636 else
637 parser->template.ndots = RES_MAXNDOTS;
638 }
639 else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
640 {
641 int i = atoi (cp + sizeof ("timeout:") - 1);
642 if (i <= RES_MAXRETRANS)
643 parser->template.retrans = i;
644 else
645 parser->template.retrans = RES_MAXRETRANS;
646 }
647 else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
648 {
649 int i = atoi (cp + sizeof ("attempts:") - 1);
650 if (i <= RES_MAXRETRY)
651 parser->template.retry = i;
652 else
653 parser->template.retry = RES_MAXRETRY;
654 }
655 else
656 {
657 static const struct
658 {
659 char str[22];
660 uint8_t len;
661 uint8_t clear;
662 unsigned long int flag;
663 } options[] = {
664#define STRnLEN(str) str, sizeof (str) - 1
665 { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
666 { STRnLEN ("rotate"), 0, RES_ROTATE },
667 { STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
668 { STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
669 { STRnLEN ("single-request"), 0, RES_SNGLKUP },
670 { STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
671 { STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
672 { STRnLEN ("no-reload"), 0, RES_NORELOAD },
673 { STRnLEN ("use-vc"), 0, RES_USEVC }
674 };
675#define noptions (sizeof (options) / sizeof (options[0]))
676 for (int i = 0; i < noptions; ++i)
677 if (strncmp (cp, options[i].str, options[i].len) == 0)
678 {
679 if (options[i].clear)
680 parser->template.options &= options[i].flag;
681 else
682 parser->template.options |= options[i].flag;
683 break;
684 }
685 }
686 /* Skip to next run of spaces. */
687 while (*cp && *cp != ' ' && *cp != '\t')
688 cp++;
689 }
690}
691
692static uint32_t
693net_mask (struct in_addr in)
694{
695 uint32_t i = ntohl (in.s_addr);
696
697 if (IN_CLASSA (i))
698 return htonl (IN_CLASSA_NET);
699 else if (IN_CLASSB (i))
700 return htonl (IN_CLASSB_NET);
701 return htonl (IN_CLASSC_NET);
702}
703