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[glibc.git] / resolv / res_hconf.c
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1 /* Copyright (C) 1993, 1995-2001, 2002 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by David Mosberger (davidm@azstarnet.com).
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
20 /* This file provides a Linux /etc/host.conf compatible front end to
21 the various name resolvers (/etc/hosts, named, NIS server, etc.).
22 Though mostly compatibly, the following differences exist compared
23 to the original implementation:
25 - new command "spoof" takes an arguments like RESOLV_SPOOF_CHECK
26 environment variable (i.e., `off', `nowarn', or `warn').
28 - line comments can appear anywhere (not just at the beginning of
29 a line)
32 #include <errno.h>
33 #include <ctype.h>
34 #include <libintl.h>
35 #include <memory.h>
36 #include <stdio.h>
37 #include <stdio_ext.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <net/if.h>
41 #include <sys/ioctl.h>
42 #include <unistd.h>
43 #include <netinet/in.h>
44 #include <bits/libc-lock.h>
45 #include "ifreq.h"
46 #include "res_hconf.h"
47 #ifdef USE_IN_LIBIO
48 # include <wchar.h>
49 #endif
51 #define _PATH_HOSTCONF "/etc/host.conf"
53 /* Environment vars that all user to override default behavior: */
54 #define ENV_HOSTCONF "RESOLV_HOST_CONF"
55 #define ENV_SERVORDER "RESOLV_SERV_ORDER"
56 #define ENV_SPOOF "RESOLV_SPOOF_CHECK"
57 #define ENV_TRIM_OVERR "RESOLV_OVERRIDE_TRIM_DOMAINS"
58 #define ENV_TRIM_ADD "RESOLV_ADD_TRIM_DOMAINS"
59 #define ENV_MULTI "RESOLV_MULTI"
60 #define ENV_REORDER "RESOLV_REORDER"
62 static const char *arg_service_list (const char *, int, const char *,
63 unsigned int);
64 static const char *arg_trimdomain_list (const char *, int, const char *,
65 unsigned int);
66 static const char *arg_spoof (const char *, int, const char *, unsigned int);
67 static const char *arg_bool (const char *, int, const char *, unsigned int);
69 static struct cmd
71 const char *name;
72 const char *(*parse_args) (const char * filename, int line_num,
73 const char * args, unsigned int arg);
74 unsigned int arg;
75 } cmd[] =
77 {"order", arg_service_list, 0},
78 {"trim", arg_trimdomain_list, 0},
79 {"spoof", arg_spoof, 0},
80 {"multi", arg_bool, HCONF_FLAG_MULTI},
81 {"nospoof", arg_bool, HCONF_FLAG_SPOOF},
82 {"spoofalert", arg_bool, HCONF_FLAG_SPOOFALERT},
83 {"reorder", arg_bool, HCONF_FLAG_REORDER}
86 /* Structure containing the state. */
87 struct hconf _res_hconf;
89 /* Skip white space. */
90 static const char *
91 skip_ws (const char *str)
93 while (isspace (*str)) ++str;
94 return str;
98 /* Skip until whitespace, comma, end of line, or comment character. */
99 static const char *
100 skip_string (const char *str)
102 while (*str && !isspace (*str) && *str != '#' && *str != ',')
103 ++str;
104 return str;
108 static const char *
109 arg_service_list (const char *fname, int line_num, const char *args,
110 unsigned int arg)
112 enum Name_Service service;
113 const char *start;
114 size_t len;
115 int i;
116 static struct
118 const char * name;
119 enum Name_Service service;
120 } svcs[] =
122 {"bind", SERVICE_BIND},
123 {"hosts", SERVICE_HOSTS},
124 {"nis", SERVICE_NIS},
129 start = args;
130 args = skip_string (args);
131 len = args - start;
133 service = SERVICE_NONE;
134 for (i = 0; i < sizeof (svcs) / sizeof (svcs[0]); ++i)
136 if (__strncasecmp (start, svcs[i].name, len) == 0
137 && len == strlen (svcs[i].name))
139 service = svcs[i].service;
140 break;
143 if (service == SERVICE_NONE)
145 char *buf;
147 __asprintf (&buf, _("%s: line %d: expected service, found `%s'\n"),
148 fname, line_num, start);
150 #ifdef USE_IN_LIBIO
151 if (_IO_fwide (stderr, 0) > 0)
152 __fwprintf (stderr, L"%s", buf);
153 else
154 #endif
155 fputs (buf, stderr);
157 free (buf);
158 return 0;
160 if (_res_hconf.num_services >= SERVICE_MAX)
162 char *buf;
164 __asprintf (&buf,
165 _("%s: line %d: cannot specify more than %d services"),
166 fname, line_num, SERVICE_MAX);
168 #ifdef USE_IN_LIBIO
169 if (_IO_fwide (stderr, 0) > 0)
170 __fwprintf (stderr, L"%s", buf);
171 else
172 #endif
173 fputs (buf, stderr);
175 free (buf);
176 return 0;
178 _res_hconf.service[_res_hconf.num_services++] = service;
180 args = skip_ws (args);
181 switch (*args)
183 case ',':
184 case ';':
185 case ':':
186 args = skip_ws (++args);
187 if (!*args || *args == '#')
189 char *buf;
191 __asprintf (&buf, _("\
192 %s: line %d: list delimiter not followed by keyword"),
193 fname, line_num);
195 #ifdef USE_IN_LIBIO
196 if (_IO_fwide (stderr, 0) > 0)
197 __fwprintf (stderr, L"%s", buf);
198 else
199 #endif
200 fputs (buf, stderr);
202 free (buf);
203 return 0;
205 default:
206 break;
209 while (*args && *args != '#');
210 return args;
214 static const char *
215 arg_trimdomain_list (const char *fname, int line_num, const char *args,
216 unsigned int flag)
218 const char * start;
219 size_t len;
223 start = args;
224 args = skip_string (args);
225 len = args - start;
227 if (_res_hconf.num_trimdomains >= TRIMDOMAINS_MAX)
229 char *buf;
231 __asprintf (&buf, _("\
232 %s: line %d: cannot specify more than %d trim domains"),
233 fname, line_num, TRIMDOMAINS_MAX);
235 #ifdef USE_IN_LIBIO
236 if (_IO_fwide (stderr, 0) > 0)
237 __fwprintf (stderr, L"%s", buf);
238 else
239 #endif
240 fputs (buf, stderr);
242 free (buf);
243 return 0;
245 _res_hconf.trimdomain[_res_hconf.num_trimdomains++] =
246 __strndup (start, len);
247 args = skip_ws (args);
248 switch (*args)
250 case ',': case ';': case ':':
251 args = skip_ws (++args);
252 if (!*args || *args == '#')
254 char *buf;
256 __asprintf (&buf, _("\
257 %s: line %d: list delimiter not followed by domain"),
258 fname, line_num);
260 #ifdef USE_IN_LIBIO
261 if (_IO_fwide (stderr, 0) > 0)
262 __fwprintf (stderr, L"%s", buf);
263 else
264 #endif
265 fputs (buf, stderr);
267 free (buf);
268 return 0;
270 default:
271 break;
274 while (*args && *args != '#');
275 return args;
279 static const char *
280 arg_spoof (const char *fname, int line_num, const char *args, unsigned flag)
282 const char *start = args;
283 size_t len;
285 args = skip_string (args);
286 len = args - start;
288 if (len == 3 && __strncasecmp (start, "off", len) == 0)
289 _res_hconf.flags &= ~(HCONF_FLAG_SPOOF | HCONF_FLAG_SPOOFALERT);
290 else
292 _res_hconf.flags |= (HCONF_FLAG_SPOOF | HCONF_FLAG_SPOOFALERT);
293 if ((len == 6 && __strncasecmp (start, "nowarn", len) == 0)
294 || !(len == 4 && __strncasecmp (start, "warn", len) == 0))
295 _res_hconf.flags &= ~HCONF_FLAG_SPOOFALERT;
297 return args;
301 static const char *
302 arg_bool (const char *fname, int line_num, const char *args, unsigned flag)
304 if (__strncasecmp (args, "on", 2) == 0)
306 args += 2;
307 _res_hconf.flags |= flag;
309 else if (__strncasecmp (args, "off", 3) == 0)
311 args += 3;
312 _res_hconf.flags &= ~flag;
314 else
316 char *buf;
318 __asprintf (&buf,
319 _("%s: line %d: expected `on' or `off', found `%s'\n"),
320 fname, line_num, args);
322 #ifdef USE_IN_LIBIO
323 if (_IO_fwide (stderr, 0) > 0)
324 __fwprintf (stderr, L"%s", buf);
325 else
326 #endif
327 fputs (buf, stderr);
329 free (buf);
330 return 0;
332 return args;
336 static void
337 parse_line (const char *fname, int line_num, const char *str)
339 const char *start;
340 struct cmd *c = 0;
341 size_t len;
342 int i;
344 str = skip_ws (str);
346 /* skip line comment and empty lines: */
347 if (*str == '\0' || *str == '#') return;
349 start = str;
350 str = skip_string (str);
351 len = str - start;
353 for (i = 0; i < sizeof (cmd) / sizeof (cmd[0]); ++i)
355 if (__strncasecmp (start, cmd[i].name, len) == 0
356 && strlen (cmd[i].name) == len)
358 c = &cmd[i];
359 break;
362 if (c == NULL)
364 char *buf;
366 __asprintf (&buf, _("%s: line %d: bad command `%s'\n"),
367 fname, line_num, start);
369 #ifdef USE_IN_LIBIO
370 if (_IO_fwide (stderr, 0) > 0)
371 __fwprintf (stderr, L"%s", buf);
372 else
373 #endif
374 fputs (buf, stderr);
376 free (buf);
377 return;
380 /* process args: */
381 str = skip_ws (str);
382 str = (*c->parse_args) (fname, line_num, str, c->arg);
383 if (!str)
384 return;
386 /* rest of line must contain white space or comment only: */
387 while (*str)
389 if (!isspace (*str)) {
390 if (*str != '#')
392 char *buf;
394 __asprintf (&buf,
395 _("%s: line %d: ignoring trailing garbage `%s'\n"),
396 fname, line_num, str);
398 #ifdef USE_IN_LIBIO
399 if (_IO_fwide (stderr, 0) > 0)
400 __fwprintf (stderr, L"%s", buf);
401 else
402 #endif
403 fputs (buf, stderr);
405 free (buf);
407 break;
409 ++str;
414 static void
415 do_init (void)
417 const char *hconf_name;
418 int line_num = 0;
419 char buf[256], *envval;
420 FILE *fp;
422 memset (&_res_hconf, '\0', sizeof (_res_hconf));
424 hconf_name = getenv (ENV_HOSTCONF);
425 if (hconf_name == NULL)
426 hconf_name = _PATH_HOSTCONF;
428 fp = fopen (hconf_name, "r");
429 if (!fp)
430 /* make up something reasonable: */
431 _res_hconf.service[_res_hconf.num_services++] = SERVICE_BIND;
432 else
434 /* No threads using this stream. */
435 __fsetlocking (fp, FSETLOCKING_BYCALLER);
437 while (fgets_unlocked (buf, sizeof (buf), fp))
439 ++line_num;
440 *__strchrnul (buf, '\n') = '\0';
441 parse_line (hconf_name, line_num, buf);
443 fclose (fp);
446 envval = getenv (ENV_SERVORDER);
447 if (envval)
449 _res_hconf.num_services = 0;
450 arg_service_list (ENV_SERVORDER, 1, envval, 0);
453 envval = getenv (ENV_SPOOF);
454 if (envval)
455 arg_spoof (ENV_SPOOF, 1, envval, 0);
457 envval = getenv (ENV_MULTI);
458 if (envval)
459 arg_bool (ENV_MULTI, 1, envval, HCONF_FLAG_MULTI);
461 envval = getenv (ENV_REORDER);
462 if (envval)
463 arg_bool (ENV_REORDER, 1, envval, HCONF_FLAG_REORDER);
465 envval = getenv (ENV_TRIM_ADD);
466 if (envval)
467 arg_trimdomain_list (ENV_TRIM_ADD, 1, envval, 0);
469 envval = getenv (ENV_TRIM_OVERR);
470 if (envval)
472 _res_hconf.num_trimdomains = 0;
473 arg_trimdomain_list (ENV_TRIM_OVERR, 1, envval, 0);
476 _res_hconf.initialized = 1;
480 /* Initialize hconf datastructure by reading host.conf file and
481 environment variables. */
482 void
483 _res_hconf_init (void)
485 __libc_once_define (static, once);
487 __libc_once (once, do_init);
491 /* List of known interfaces. */
492 static struct netaddr
494 int addrtype;
495 union
497 struct
499 u_int32_t addr;
500 u_int32_t mask;
501 } ipv4;
502 } u;
503 } *ifaddrs;
505 /* We need to protect the dynamic buffer handling. */
506 __libc_lock_define_initialized (static, lock);
508 /* Reorder addresses returned in a hostent such that the first address
509 is an address on the local subnet, if there is such an address.
510 Otherwise, nothing is changed.
512 Note that this function currently only handles IPv4 addresses. */
514 void
515 _res_hconf_reorder_addrs (struct hostent *hp)
517 #if defined SIOCGIFCONF && defined SIOCGIFNETMASK
518 int i, j;
519 /* Number of interfaces. */
520 static int num_ifs = -1;
522 /* Only reorder if we're supposed to. */
523 if ((_res_hconf.flags & HCONF_FLAG_REORDER) == 0)
524 return;
526 /* Can't deal with anything but IPv4 for now... */
527 if (hp->h_addrtype != AF_INET)
528 return;
530 if (num_ifs <= 0)
532 struct ifreq *ifr, *cur_ifr;
533 int sd, num, i;
534 /* Save errno. */
535 int save = errno;
537 /* Initialize interface table. */
539 num_ifs = 0;
541 /* The SIOCGIFNETMASK ioctl will only work on an AF_INET socket. */
542 sd = __socket (AF_INET, SOCK_DGRAM, 0);
543 if (sd < 0)
544 return;
546 /* Get lock. */
547 __libc_lock_lock (lock);
549 /* Get a list of interfaces. */
550 __ifreq (&ifr, &num, sd);
551 if (!ifr)
552 goto cleanup;
554 ifaddrs = malloc (num * sizeof (ifaddrs[0]));
555 if (!ifaddrs)
556 goto cleanup1;
558 /* Copy usable interfaces in ifaddrs structure. */
559 for (cur_ifr = ifr, i = 0; i < num; ++cur_ifr, ++i)
561 if (cur_ifr->ifr_addr.sa_family != AF_INET)
562 continue;
564 ifaddrs[num_ifs].addrtype = AF_INET;
565 ifaddrs[num_ifs].u.ipv4.addr =
566 ((struct sockaddr_in *) &cur_ifr->ifr_addr)->sin_addr.s_addr;
568 if (__ioctl (sd, SIOCGIFNETMASK, cur_ifr) < 0)
569 continue;
571 ifaddrs[num_ifs].u.ipv4.mask =
572 ((struct sockaddr_in *) &cur_ifr->ifr_netmask)->sin_addr.s_addr;
574 /* Now we're committed to this entry. */
575 ++num_ifs;
577 /* Just keep enough memory to hold all the interfaces we want. */
578 ifaddrs = realloc (ifaddrs, num_ifs * sizeof (ifaddrs[0]));
580 cleanup1:
581 __if_freereq (ifr, num);
583 cleanup:
584 /* Release lock, preserve error value, and close socket. */
585 save = errno;
586 __libc_lock_unlock (lock);
587 __close (sd);
590 if (num_ifs == 0)
591 return;
593 /* Find an address for which we have a direct connection. */
594 for (i = 0; hp->h_addr_list[i]; ++i)
596 struct in_addr *haddr = (struct in_addr *) hp->h_addr_list[i];
598 for (j = 0; j < num_ifs; ++j)
600 u_int32_t if_addr = ifaddrs[j].u.ipv4.addr;
601 u_int32_t if_netmask = ifaddrs[j].u.ipv4.mask;
603 if (((haddr->s_addr ^ if_addr) & if_netmask) == 0)
605 void *tmp;
607 tmp = hp->h_addr_list[i];
608 hp->h_addr_list[i] = hp->h_addr_list[0];
609 hp->h_addr_list[0] = tmp;
610 return;
614 #endif /* defined(SIOCGIFCONF) && ... */
618 /* If HOSTNAME has a postfix matching any of the trimdomains, trim away
619 that postfix. Notice that HOSTNAME is modified inplace. Also, the
620 original code applied all trimdomains in order, meaning that the
621 same domainname could be trimmed multiple times. I believe this
622 was unintentional. */
623 void
624 _res_hconf_trim_domain (char *hostname)
626 size_t hostname_len, trim_len;
627 int i;
629 hostname_len = strlen (hostname);
631 for (i = 0; i < _res_hconf.num_trimdomains; ++i)
633 const char *trim = _res_hconf.trimdomain[i];
635 trim_len = strlen (trim);
636 if (hostname_len > trim_len
637 && __strcasecmp (&hostname[hostname_len - trim_len], trim) == 0)
639 hostname[hostname_len - trim_len] = '\0';
640 break;
646 /* Trim all hostnames/aliases in HP according to the trimdomain list.
647 Notice that HP is modified inplace! */
648 void
649 _res_hconf_trim_domains (struct hostent *hp)
651 int i;
653 if (_res_hconf.num_trimdomains == 0)
654 return;
656 _res_hconf_trim_domain (hp->h_name);
657 for (i = 0; hp->h_aliases[i]; ++i)
658 _res_hconf_trim_domain (hp->h_aliases[i]);
662 /* Free all resources if necessary. */
663 static void __attribute__ ((unused))
664 free_mem (void)
666 free (ifaddrs);
669 text_set_element (__libc_subfreeres, free_mem);