#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "$Id: hesiod.c,v 1.7 2005/07/28 06:51:48 marka Exp $";
#endif
/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1996,1999 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*! \file
* \brief
* hesiod.c --- the core portion of the hesiod resolver.
*
* This file is derived from the hesiod library from Project Athena;
* It has been extensively rewritten by Theodore Ts'o to have a more
* thread-safe interface.
* \author
* This file is primarily maintained by <tytso@mit.edu> and <ghudson@mit.edu>.
*/
/* Imports */
#include "port_before.h"
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "port_after.h"
#include "pathnames.h"
#include "hesiod.h"
#include "hesiod_p.h"
/* Forward */
int hesiod_init(void **context);
void hesiod_end(void *context);
char * hesiod_to_bind(void *context, const char *name,
const char *type);
char ** hesiod_resolve(void *context, const char *name,
const char *type);
void hesiod_free_list(void *context, char **list);
static int parse_config_file(struct hesiod_p *ctx, const char *filename);
static char ** get_txt_records(struct hesiod_p *ctx, int class,
const char *name);
static int init(struct hesiod_p *ctx);
/* Public */
/*%
* This function is called to initialize a hesiod_p.
*/
int
hesiod_init(void **context) {
struct hesiod_p *ctx;
char *cp;
ctx = malloc(sizeof(struct hesiod_p));
if (ctx == 0) {
errno = ENOMEM;
return (-1);
}
memset(ctx, 0, sizeof (*ctx));
if (parse_config_file(ctx, _PATH_HESIOD_CONF) < 0) {
#ifdef DEF_RHS
/*
* Use compiled in defaults.
*/
ctx->LHS = malloc(strlen(DEF_LHS) + 1);
ctx->RHS = malloc(strlen(DEF_RHS) + 1);
if (ctx->LHS == NULL || ctx->RHS == NULL) {
errno = ENOMEM;
goto cleanup;
}
strcpy(ctx->LHS, DEF_LHS); /* (checked) */
strcpy(ctx->RHS, DEF_RHS); /* (checked) */
#else
goto cleanup;
#endif
}
/*
* The default RHS can be overridden by an environment
* variable.
*/
if ((cp = getenv("HES_DOMAIN")) != NULL) {
size_t RHSlen = strlen(cp) + 2;
if (ctx->RHS)
free(ctx->RHS);
ctx->RHS = malloc(RHSlen);
if (!ctx->RHS) {
errno = ENOMEM;
goto cleanup;
}
if (cp[0] == '.') {
strcpy(ctx->RHS, cp); /* (checked) */
} else {
strcpy(ctx->RHS, "."); /* (checked) */
strcat(ctx->RHS, cp); /* (checked) */
}
}
/*
* If there is no default hesiod realm set, we return an
* error.
*/
if (!ctx->RHS) {
errno = ENOEXEC;
goto cleanup;
}
#if 0
if (res_ninit(ctx->res) < 0)
goto cleanup;
#endif
*context = ctx;
return (0);
cleanup:
hesiod_end(ctx);
return (-1);
}
/*%
* This function deallocates the hesiod_p
*/
void
hesiod_end(void *context) {
struct hesiod_p *ctx = (struct hesiod_p *) context;
int save_errno = errno;
if (ctx->res)
res_nclose(ctx->res);
if (ctx->RHS)
free(ctx->RHS);
if (ctx->LHS)
free(ctx->LHS);
if (ctx->res && ctx->free_res)
(*ctx->free_res)(ctx->res);
free(ctx);
errno = save_errno;
}
/*%
* This function takes a hesiod (name, type) and returns a DNS
* name which is to be resolved.
*/
char *
hesiod_to_bind(void *context, const char *name, const char *type) {
struct hesiod_p *ctx = (struct hesiod_p *) context;
char *bindname;
char **rhs_list = NULL;
const char *RHS, *cp;
/* Decide what our RHS is, and set cp to the end of the actual name. */
if ((cp = strchr(name, '@')) != NULL) {
if (strchr(cp + 1, '.'))
RHS = cp + 1;
else if ((rhs_list = hesiod_resolve(context, cp + 1,
"rhs-extension")) != NULL)
RHS = *rhs_list;
else {
errno = ENOENT;
return (NULL);
}
} else {
RHS = ctx->RHS;
cp = name + strlen(name);
}
/*
* Allocate the space we need, including up to three periods and
* the terminating NUL.
*/
if ((bindname = malloc((cp - name) + strlen(type) + strlen(RHS) +
(ctx->LHS ? strlen(ctx->LHS) : 0) + 4)) == NULL) {
errno = ENOMEM;
if (rhs_list)
hesiod_free_list(context, rhs_list);
return NULL;
}
/* Now put together the DNS name. */
memcpy(bindname, name, cp - name);
bindname[cp - name] = '\0';
strcat(bindname, ".");
strcat(bindname, type);
if (ctx->LHS) {
if (ctx->LHS[0] != '.')
strcat(bindname, ".");
strcat(bindname, ctx->LHS);
}
if (RHS[0] != '.')
strcat(bindname, ".");
strcat(bindname, RHS);
if (rhs_list)
hesiod_free_list(context, rhs_list);
return (bindname);
}
/*%
* This is the core function. Given a hesiod (name, type), it
* returns an array of strings returned by the resolver.
*/
char **
hesiod_resolve(void *context, const char *name, const char *type) {
struct hesiod_p *ctx = (struct hesiod_p *) context;
char *bindname = hesiod_to_bind(context, name, type);
char **retvec;
if (bindname == NULL)
return (NULL);
if (init(ctx) == -1) {
free(bindname);
return (NULL);
}
if ((retvec = get_txt_records(ctx, C_IN, bindname))) {
free(bindname);
return (retvec);
}
if (errno != ENOENT)
return (NULL);
retvec = get_txt_records(ctx, C_HS, bindname);
free(bindname);
return (retvec);
}
void
hesiod_free_list(void *context, char **list) {
char **p;
UNUSED(context);
for (p = list; *p; p++)
free(*p);
free(list);
}
/*%
* This function parses the /etc/hesiod.conf file
*/
static int
parse_config_file(struct hesiod_p *ctx, const char *filename) {
char *key, *data, *cp, **cpp;
char buf[MAXDNAME+7];
FILE *fp;
/*
* Clear the existing configuration variable, just in case
* they're set.
*/
if (ctx->RHS)
free(ctx->RHS);
if (ctx->LHS)
free(ctx->LHS);
ctx->RHS = ctx->LHS = 0;
/*
* Now open and parse the file...
*/
if (!(fp = fopen(filename, "r")))
return (-1);
while (fgets(buf, sizeof(buf), fp) != NULL) {
cp = buf;
if (*cp == '#' || *cp == '\n' || *cp == '\r')
continue;
while(*cp == ' ' || *cp == '\t')
cp++;
key = cp;
while(*cp != ' ' && *cp != '\t' && *cp != '=')
cp++;
*cp++ = '\0';
while(*cp == ' ' || *cp == '\t' || *cp == '=')
cp++;
data = cp;
while(*cp != ' ' && *cp != '\n' && *cp != '\r')
cp++;
*cp++ = '\0';
if (strcmp(key, "lhs") == 0)
cpp = &ctx->LHS;
else if (strcmp(key, "rhs") == 0)
cpp = &ctx->RHS;
else
continue;
*cpp = malloc(strlen(data) + 1);
if (!*cpp) {
errno = ENOMEM;
goto cleanup;
}
strcpy(*cpp, data);
}
fclose(fp);
return (0);
cleanup:
fclose(fp);
if (ctx->RHS)
free(ctx->RHS);
if (ctx->LHS)
free(ctx->LHS);
ctx->RHS = ctx->LHS = 0;
return (-1);
}
/*%
* Given a DNS class and a DNS name, do a lookup for TXT records, and
* return a list of them.
*/
static char **
get_txt_records(struct hesiod_p *ctx, int class, const char *name) {
struct {
int type; /*%< RR type */
int class; /*%< RR class */
int dlen; /*%< len of data section */
u_char *data; /*%< pointer to data */
} rr;
HEADER *hp;
u_char qbuf[MAX_HESRESP], abuf[MAX_HESRESP];
u_char *cp, *erdata, *eom;
char *dst, *edst, **list;
int ancount, qdcount;
int i, j, n, skip;
/*
* Construct the query and send it.
*/
n = res_nmkquery(ctx->res, QUERY, name, class, T_TXT, NULL, 0,
NULL, qbuf, MAX_HESRESP);
if (n < 0) {
errno = EMSGSIZE;
return (NULL);
}
n = res_nsend(ctx->res, qbuf, n, abuf, MAX_HESRESP);
if (n < 0) {
errno = ECONNREFUSED;
return (NULL);
}
if (n < HFIXEDSZ) {
errno = EMSGSIZE;
return (NULL);
}
/*
* OK, parse the result.
*/
hp = (HEADER *) abuf;
ancount = ntohs(hp->ancount);
qdcount = ntohs(hp->qdcount);
cp = abuf + sizeof(HEADER);
eom = abuf + n;
/* Skip query, trying to get to the answer section which follows. */
for (i = 0; i < qdcount; i++) {
skip = dn_skipname(cp, eom);
if (skip < 0 || cp + skip + QFIXEDSZ > eom) {
errno = EMSGSIZE;
return (NULL);
}
cp += skip + QFIXEDSZ;
}
list = malloc((ancount + 1) * sizeof(char *));
if (!list) {
errno = ENOMEM;
return (NULL);
}
j = 0;
for (i = 0; i < ancount; i++) {
skip = dn_skipname(cp, eom);
if (skip < 0) {
errno = EMSGSIZE;
goto cleanup;
}
cp += skip;
if (cp + 3 * INT16SZ + INT32SZ > eom) {
errno = EMSGSIZE;
goto cleanup;
}
rr.type = ns_get16(cp);
cp += INT16SZ;
rr.class = ns_get16(cp);
cp += INT16SZ + INT32SZ; /*%< skip the ttl, too */
rr.dlen = ns_get16(cp);
cp += INT16SZ;
if (cp + rr.dlen > eom) {
errno = EMSGSIZE;
goto cleanup;
}
rr.data = cp;
cp += rr.dlen;
if (rr.class != class || rr.type != T_TXT)
continue;
if (!(list[j] = malloc(rr.dlen)))
goto cleanup;
dst = list[j++];
edst = dst + rr.dlen;
erdata = rr.data + rr.dlen;
cp = rr.data;
while (cp < erdata) {
n = (unsigned char) *cp++;
if (cp + n > eom || dst + n > edst) {
errno = EMSGSIZE;
goto cleanup;
}
memcpy(dst, cp, n);
cp += n;
dst += n;
}
if (cp != erdata) {
errno = EMSGSIZE;
goto cleanup;
}
*dst = '\0';
}
list[j] = NULL;
if (j == 0) {
errno = ENOENT;
goto cleanup;
}
return (list);
cleanup:
for (i = 0; i < j; i++)
free(list[i]);
free(list);
return (NULL);
}
struct __res_state *
__hesiod_res_get(void *context) {
struct hesiod_p *ctx = context;
if (!ctx->res) {
struct __res_state *res;
res = (struct __res_state *)malloc(sizeof *res);
if (res == NULL) {
errno = ENOMEM;
return (NULL);
}
memset(res, 0, sizeof *res);
__hesiod_res_set(ctx, res, free);
}
return (ctx->res);
}
void
__hesiod_res_set(void *context, struct __res_state *res,
void (*free_res)(void *)) {
struct hesiod_p *ctx = context;
if (ctx->res && ctx->free_res) {
res_nclose(ctx->res);
(*ctx->free_res)(ctx->res);
}
ctx->res = res;
ctx->free_res = free_res;
}
static int
init(struct hesiod_p *ctx) {
if (!ctx->res && !__hesiod_res_get(ctx))
return (-1);
if (((ctx->res->options & RES_INIT) == 0U) &&
(res_ninit(ctx->res) == -1))
return (-1);
return (0);
}