1 #if defined(LIBC_SCCS) && !defined(lint)
2 static const char rcsid[] = "$BINDId: hesiod.c,v 1.21 2000/02/28 14:51:08 vixie Exp $";
6 * Copyright (c) 1996,1999 by Internet Software Consortium.
8 * Permission to use, copy, modify, and distribute this software for any
9 * purpose with or without fee is hereby granted, provided that the above
10 * copyright notice and this permission notice appear in all copies.
12 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
13 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
14 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
15 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
16 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
17 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
18 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
23 * This file is primarily maintained by <tytso@mit.edu> and <ghudson@mit.edu>.
27 * hesiod.c --- the core portion of the hesiod resolver.
29 * This file is derived from the hesiod library from Project Athena;
30 * It has been extensively rewritten by Theodore Ts'o to have a more
31 * thread-safe interface.
36 #include <sys/types.h>
37 #include <netinet/in.h>
38 #include <arpa/nameser.h>
51 #define _PATH_HESIOD_CONF "/etc/hesiod.conf"
55 int hesiod_init(void **context);
56 void hesiod_end(void *context);
57 char * hesiod_to_bind(void *context, const char *name,
59 char ** hesiod_resolve(void *context, const char *name,
61 void hesiod_free_list(void *context, char **list);
63 static int parse_config_file(struct hesiod_p *ctx, const char *filename);
64 static char ** get_txt_records(struct hesiod_p *ctx, int class,
66 static int init(struct hesiod_p *ctx);
71 * This function is called to initialize a hesiod_p.
74 hesiod_init(void **context) {
76 const char *configname;
79 ctx = malloc(sizeof(struct hesiod_p));
86 /* Set default query classes. */
87 ctx->classes[0] = C_IN;
88 ctx->classes[1] = C_HS;
90 configname = __libc_secure_getenv("HESIOD_CONFIG");
92 configname = _PATH_HESIOD_CONF;
93 if (parse_config_file(ctx, configname) < 0) {
96 * Use compiled in defaults.
98 ctx->LHS = malloc(strlen(DEF_LHS)+1);
99 ctx->RHS = malloc(strlen(DEF_RHS)+1);
100 if (ctx->LHS == 0 || ctx->RHS == 0)
102 strcpy(ctx->LHS, DEF_LHS);
103 strcpy(ctx->RHS, DEF_RHS);
109 * The default RHS can be overridden by an environment
112 if ((cp = __libc_secure_getenv("HES_DOMAIN")) != NULL) {
114 ctx->RHS = malloc(strlen(cp)+2);
118 strcpy(ctx->RHS, cp);
121 strcpy(ctx->RHS + 1, cp);
126 * If there is no default hesiod realm set, we return an
130 __set_errno(ENOEXEC);
135 if (res_ninit(ctx->res) < 0)
148 * This function deallocates the hesiod_p
151 hesiod_end(void *context) {
152 struct hesiod_p *ctx = (struct hesiod_p *) context;
153 int save_errno = errno;
156 res_nclose(ctx->res);
159 if (ctx->res && ctx->free_res)
160 (*ctx->free_res)(ctx->res);
162 __set_errno(save_errno);
166 * This function takes a hesiod (name, type) and returns a DNS
167 * name which is to be resolved.
170 hesiod_to_bind(void *context, const char *name, const char *type) {
171 struct hesiod_p *ctx = (struct hesiod_p *) context;
173 char **rhs_list = NULL;
174 const char *RHS, *cp;
177 /* Decide what our RHS is, and set cp to the end of the actual name. */
178 if ((cp = strchr(name, '@')) != NULL) {
179 if (strchr(cp + 1, '.'))
181 else if ((rhs_list = hesiod_resolve(context, cp + 1,
182 "rhs-extension")) != NULL)
190 cp = name + strlen(name);
194 * Allocate the space we need, including up to three periods and
195 * the terminating NUL.
197 if ((bindname = malloc((cp - name) + strlen(type) + strlen(RHS) +
198 (ctx->LHS ? strlen(ctx->LHS) : 0) + 4)) == NULL) {
200 hesiod_free_list(context, rhs_list);
204 /* Now put together the DNS name. */
205 endp = (char *) __mempcpy (bindname, name, cp - name);
207 endp = (char *) __stpcpy (endp, type);
209 if (ctx->LHS[0] != '.')
211 endp = __stpcpy (endp, ctx->LHS);
218 hesiod_free_list(context, rhs_list);
224 * This is the core function. Given a hesiod (name, type), it
225 * returns an array of strings returned by the resolver.
228 hesiod_resolve(void *context, const char *name, const char *type) {
229 struct hesiod_p *ctx = (struct hesiod_p *) context;
230 char *bindname = hesiod_to_bind(context, name, type);
233 if (bindname == NULL)
235 if (init(ctx) == -1) {
240 retvec = get_txt_records(ctx, ctx->classes[0], bindname);
242 if (retvec == NULL && (errno == ENOENT || errno == ECONNREFUSED) && ctx->classes[1])
243 retvec = get_txt_records(ctx, ctx->classes[1], bindname);
251 hesiod_free_list(void *context, char **list) {
254 for (p = list; *p; p++)
260 * This function parses the /etc/hesiod.conf file
263 parse_config_file(struct hesiod_p *ctx, const char *filename) {
264 char buf[MAXDNAME+7];
268 * Clear the existing configuration variable, just in case
273 ctx->RHS = ctx->LHS = 0;
274 /* Set default query classes. */
275 ctx->classes[0] = C_IN;
276 ctx->classes[1] = C_HS;
279 * Now open and parse the file...
281 if (!(fp = fopen(filename, "rce")))
284 while (fgets(buf, sizeof(buf), fp) != NULL) {
285 char *key, *data, *cp, **cpp;
288 if (*cp == '#' || *cp == '\n' || *cp == '\r')
290 while(*cp == ' ' || *cp == '\t')
293 while(*cp != ' ' && *cp != '\t' && *cp != '=')
297 while(*cp == ' ' || *cp == '\t' || *cp == '=')
300 while(*cp != ' ' && *cp != '\n' && *cp != '\r')
305 if (strcasecmp(key, "lhs") == 0)
307 else if (strcasecmp(key, "rhs") == 0)
313 } else if (strcasecmp(key, "classes") == 0) {
315 while (*data && n < 2) {
316 cp = strchrnul(data, ',');
319 if (strcasecmp(data, "IN") == 0)
320 ctx->classes[n++] = C_IN;
321 else if (strcasecmp(data, "HS") == 0)
322 ctx->classes[n++] = C_HS;
326 /* Restore the default. Better than
328 ctx->classes[0] = C_IN;
329 ctx->classes[1] = C_HS;
331 || ctx->classes[0] == ctx->classes[1])
342 ctx->RHS = ctx->LHS = 0;
347 * Given a DNS class and a DNS name, do a lookup for TXT records, and
348 * return a list of them.
351 get_txt_records(struct hesiod_p *ctx, int class, const char *name) {
353 int type; /* RR type */
354 int class; /* RR class */
355 int dlen; /* len of data section */
356 u_char *data; /* pointer to data */
359 u_char qbuf[MAX_HESRESP], abuf[MAX_HESRESP];
360 u_char *cp, *erdata, *eom;
361 char *dst, *edst, **list;
362 int ancount, qdcount;
366 * Construct the query and send it.
368 n = res_nmkquery(ctx->res, QUERY, name, class, T_TXT, NULL, 0,
369 NULL, qbuf, MAX_HESRESP);
371 __set_errno(EMSGSIZE);
374 n = res_nsend(ctx->res, qbuf, n, abuf, MAX_HESRESP);
376 __set_errno(ECONNREFUSED);
380 __set_errno(EMSGSIZE);
385 * OK, parse the result.
387 hp = (HEADER *) abuf;
388 ancount = ntohs(hp->ancount);
389 qdcount = ntohs(hp->qdcount);
390 cp = abuf + sizeof(HEADER);
393 /* Skip query, trying to get to the answer section which follows. */
394 for (i = 0; i < qdcount; i++) {
395 skip = dn_skipname(cp, eom);
396 if (skip < 0 || cp + skip + QFIXEDSZ > eom) {
397 __set_errno(EMSGSIZE);
400 cp += skip + QFIXEDSZ;
403 list = malloc((ancount + 1) * sizeof(char *));
407 for (i = 0; i < ancount; i++) {
408 skip = dn_skipname(cp, eom);
410 __set_errno(EMSGSIZE);
414 if (cp + 3 * INT16SZ + INT32SZ > eom) {
415 __set_errno(EMSGSIZE);
418 rr.type = ns_get16(cp);
420 rr.class = ns_get16(cp);
421 cp += INT16SZ + INT32SZ; /* skip the ttl, too */
422 rr.dlen = ns_get16(cp);
424 if (cp + rr.dlen > eom) {
425 __set_errno(EMSGSIZE);
430 if (rr.class != class || rr.type != T_TXT)
432 if (!(list[j] = malloc(rr.dlen)))
435 edst = dst + rr.dlen;
436 erdata = rr.data + rr.dlen;
438 while (cp < erdata) {
439 n = (unsigned char) *cp++;
440 if (cp + n > eom || dst + n > edst) {
441 __set_errno(EMSGSIZE);
449 __set_errno(EMSGSIZE);
462 for (i = 0; i < j; i++)
469 __hesiod_res_get(void *context) {
470 struct hesiod_p *ctx = context;
473 struct __res_state *res;
474 res = (struct __res_state *)calloc(1, sizeof *res);
477 __hesiod_res_set(ctx, res, free);
484 __hesiod_res_set(void *context, struct __res_state *res,
485 void (*free_res)(void *)) {
486 struct hesiod_p *ctx = context;
488 if (ctx->res && ctx->free_res) {
489 res_nclose(ctx->res);
490 (*ctx->free_res)(ctx->res);
494 ctx->free_res = free_res;
498 init(struct hesiod_p *ctx) {
500 if (!ctx->res && !__hesiod_res_get(ctx))
503 if (__res_maybe_init (ctx->res, 0) == -1)