1 /* Copyright (c) 1996 by Internet Software Consortium.
3 * Permission to use, copy, modify, and distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
7 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
8 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
9 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
10 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
11 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
12 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
13 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
17 /* Copyright 1996 by the Massachusetts Institute of Technology.
19 * Permission to use, copy, modify, and distribute this
20 * software and its documentation for any purpose and without
21 * fee is hereby granted, provided that the above copyright
22 * notice appear in all copies and that both that copyright
23 * notice and this permission notice appear in supporting
24 * documentation, and that the name of M.I.T. not be used in
25 * advertising or publicity pertaining to distribution of the
26 * software without specific, written prior permission.
27 * M.I.T. makes no representations about the suitability of
28 * this software for any purpose. It is provided "as is"
29 * without express or implied warranty.
32 /* This file is part of the hesiod library. It implements the core
33 * portion of the hesiod resolver.
35 * This file is loosely based on an interim version of hesiod.c from
36 * the BIND IRS library, which was in turn based on an earlier version
37 * of this file. Extensive changes have been made on each step of the
40 * This implementation is not truly thread-safe at the moment because
41 * it uses res_send() and accesses _res.
44 static const char rcsid[] = "$Id$";
46 #include <sys/types.h>
47 #include <netinet/in.h>
48 #include <arpa/nameser.h>
59 /* A few operating systems don't define these. */
67 static int read_config_file(struct hesiod_p *ctx, const char *filename);
68 static char **get_txt_records(struct hesiod_p *ctx, int class,
71 # define cistrcmp(s1, s2) strcasecmp (s1, s2)
73 static int cistrcmp(const char *s1, const char *s2);
76 /* This function is called to initialize a hesiod_p. */
77 int hesiod_init(void **context)
80 const char *p, *configname;
82 ctx = malloc(sizeof(struct hesiod_p));
86 configname = __secure_getenv("HESIOD_CONFIG");
88 configname = SYSCONFDIR "/hesiod.conf";
89 if (read_config_file(ctx, configname) >= 0)
91 /* The default rhs can be overridden by an environment variable. */
92 p = __secure_getenv("HES_DOMAIN");
97 ctx->rhs = malloc(strlen(p) + 2);
101 strcpy(ctx->rhs + 1, (*p == '.') ? p + 1 : p);
105 __set_errno (ENOMEM);
112 __set_errno (ENOMEM);
123 /* This function deallocates the hesiod_p. */
124 void hesiod_end(void *context)
126 struct hesiod_p *ctx = (struct hesiod_p *) context;
134 /* This function takes a hesiod (name, type) and returns a DNS
135 * name which is to be resolved.
137 char *hesiod_to_bind(void *context, const char *name, const char *type)
139 struct hesiod_p *ctx = (struct hesiod_p *) context;
140 char bindname[MAXDNAME], *p, *endp, *ret, **rhs_list = NULL;
144 endp = stpcpy(bindname, name);
146 /* Find the right right hand side to use, possibly truncating bindname. */
147 p = strchr(bindname, '@');
152 rhs = name + (p - bindname);
155 rhs_list = hesiod_resolve(context, p, "rhs-extension");
160 __set_errno (ENOENT);
167 /* See if we have enough room. */
168 len = (endp - bindname) + 1 + strlen(type);
170 len += strlen(ctx->lhs) + ((ctx->lhs[0] != '.') ? 1 : 0);
171 len += strlen(rhs) + ((rhs[0] != '.') ? 1 : 0);
172 if (len > sizeof(bindname) - 1)
175 hesiod_free_list(context, rhs_list);
176 __set_errno (EMSGSIZE);
180 /* Put together the rest of the domain. */
181 endp = __stpcpy (__stpcpy (endp, "."), type);
184 if (ctx->lhs[0] != '.')
185 endp = __stpcpy (endp, ".");
186 endp = __stpcpy (endp, ctx->lhs);
189 endp = __stpcpy (endp, ".");
190 endp = __stpcpy (endp, rhs);
192 /* rhs_list is no longer needed, since we're done with rhs. */
194 hesiod_free_list(context, rhs_list);
196 /* Make a copy of the result and return it to the caller. */
197 ret = malloc((endp - bindname) + 1);
200 __set_errno (ENOMEM);
203 strcpy(ret, bindname);
207 /* This is the core function. Given a hesiod name and type, it
208 * returns an array of strings returned by the resolver.
210 char **hesiod_resolve(void *context, const char *name, const char *type)
212 struct hesiod_p *ctx = (struct hesiod_p *) context;
213 char *bindname, **retvec;
215 bindname = hesiod_to_bind(context, name, type);
219 retvec = get_txt_records(ctx, ctx->classes[0], bindname);
220 if (retvec == NULL && errno == ENOENT && ctx->classes[1])
221 retvec = get_txt_records(ctx, ctx->classes[1], bindname);
227 void hesiod_free_list(void *context, char **list)
231 for (p = list; *p; p++)
236 /* This function parses the /etc/hesiod.conf file. Returns 0 on success,
237 * -1 on failure. On failure, it might leave values in ctx->lhs or
238 * ctx->rhs which need to be freed by the caller. */
239 static int read_config_file(struct hesiod_p *ctx, const char *filename)
241 char *key, *data, *p, **which;
242 char buf[MAXDNAME + 7];
246 /* Set default query classes. */
247 ctx->classes[0] = C_IN;
248 ctx->classes[1] = C_HS;
250 /* Try to open the configuration file. */
251 fp = fopen(filename, "r");
254 /* Use compiled in default domain names. */
255 ctx->lhs = malloc(strlen(DEF_LHS) + 1);
256 ctx->rhs = malloc(strlen(DEF_RHS) + 1);
257 if (ctx->lhs && ctx->rhs)
259 strcpy(ctx->lhs, DEF_LHS);
260 strcpy(ctx->rhs, DEF_RHS);
265 __set_errno (ENOMEM);
272 while (fgets(buf, sizeof(buf), fp) != NULL)
275 if (*p == '#' || *p == '\n' || *p == '\r')
277 while(*p == ' ' || *p == '\t')
280 while(*p != ' ' && *p != '\t' && *p != '=')
284 while(isspace(*p) || *p == '=')
291 if (cistrcmp(key, "lhs") == 0 || cistrcmp(key, "rhs") == 0)
293 which = (strcmp(key, "lhs") == 0) ? &ctx->lhs : &ctx->rhs;
294 *which = malloc(strlen(data) + 1);
297 __set_errno (ENOMEM);
300 strcpy(*which, data);
302 else if (cistrcmp(key, "classes") == 0)
305 while (*data && n < 2)
308 while (*p && *p != ',')
312 if (cistrcmp(data, "IN") == 0)
313 ctx->classes[n++] = C_IN;
314 else if (cistrcmp(data, "HS") == 0)
315 ctx->classes[n++] = C_HS;
319 ctx->classes[n++] = 0;
324 if (!ctx->rhs || ctx->classes[0] == 0 || ctx->classes[0] == ctx->classes[1])
326 __set_errno (ENOEXEC);
333 /* Given a DNS class and a DNS name, do a lookup for TXT records, and
334 * return a list of them.
336 static char **get_txt_records(struct hesiod_p *ctx, int qclass,
340 unsigned char qbuf[PACKETSZ], abuf[MAX_HESRESP], *p, *eom, *eor;
342 int ancount, qdcount, i, j, n, skip, type, class, len;
344 /* Make sure the resolver is initialized. */
345 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
348 /* Construct the query. */
349 n = res_mkquery(QUERY, name, qclass, T_TXT, NULL, 0,
350 NULL, qbuf, PACKETSZ);
354 /* Send the query. */
355 n = res_send(qbuf, n, abuf, MAX_HESRESP);
358 __set_errno (ECONNREFUSED);
362 /* Parse the header of the result. */
363 hp = (HEADER *) abuf;
364 ancount = ntohs(hp->ancount);
365 qdcount = ntohs(hp->qdcount);
366 p = abuf + sizeof(HEADER);
369 /* Skip questions, trying to get to the answer section which follows. */
370 for (i = 0; i < qdcount; i++)
372 skip = dn_skipname(p, eom);
373 if (skip < 0 || p + skip + QFIXEDSZ > eom)
375 __set_errno (EMSGSIZE);
378 p += skip + QFIXEDSZ;
381 /* Allocate space for the text record answers. */
382 list = malloc((ancount + 1) * sizeof(char *));
385 __set_errno (ENOMEM);
389 /* Parse the answers. */
391 for (i = 0; i < ancount; i++)
393 /* Parse the header of this answer. */
394 skip = dn_skipname(p, eom);
395 if (skip < 0 || p + skip + 10 > eom)
397 type = p[skip + 0] << 8 | p[skip + 1];
398 class = p[skip + 2] << 8 | p[skip + 3];
399 len = p[skip + 8] << 8 | p[skip + 9];
403 __set_errno (EMSGSIZE);
407 /* Skip entries of the wrong class and type. */
408 if (class != qclass || type != T_TXT)
414 /* Allocate space for this answer. */
415 list[j] = malloc(len);
418 __set_errno (ENOMEM);
423 /* Copy answer data into the allocated area. */
427 n = (unsigned char) *p++;
430 __set_errno (EMSGSIZE);
439 __set_errno (EMSGSIZE);
445 /* If we didn't terminate the loop normally, something went wrong. */
448 for (i = 0; i < j; i++)
456 __set_errno (ENOENT);
466 static int cistrcmp(const char *s1, const char *s2)
468 while (*s1 && tolower(*s1) == tolower(*s2))
473 return tolower(*s1) - tolower(*s2);