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+/* Copyright (c) 1996 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
+ * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
+ * CONSORTIUM 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.
+ */
+
+/* Copyright 1996 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is"
+ * without express or implied warranty.
+ */
+
+/* This file is part of the hesiod library. It implements the core
+ * portion of the hesiod resolver.
+ *
+ * This file is loosely based on an interim version of hesiod.c from
+ * the BIND IRS library, which was in turn based on an earlier version
+ * of this file. Extensive changes have been made on each step of the
+ * path.
+ *
+ * This implementation is not truly thread-safe at the moment because
+ * it uses res_send() and accesses _res.
+ */
+
+static const char rcsid[] = "$Id$";
+
+#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 <ctype.h>
+#include "hesiod.h"
+#include "hesiod_p.h"
+
+/* A few operating systems don't define these. */
+#ifndef C_HS
+#define C_HS 4
+#endif
+#ifndef T_TXT
+#define T_TXT 16
+#endif
+
+static int read_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 cistrcmp(const char *s1, const char *s2);
+
+/* This function is called to initialize a hesiod_p. */
+int hesiod_init(void **context)
+{
+ struct hesiod_p *ctx;
+ const char *p, *configname;
+
+ ctx = malloc(sizeof(struct hesiod_p));
+ if (ctx)
+ {
+ *context = ctx;
+ configname = __secure_getenv("HESIOD_CONFIG");
+ if (!configname)
+ configname = SYSCONFDIR "/hesiod.conf";
+ if (read_config_file(ctx, configname) >= 0)
+ {
+ /* The default rhs can be overridden by an environment variable. */
+ p = __secure_getenv("HES_DOMAIN");
+ if (p)
+ {
+ if (ctx->rhs)
+ free(ctx->rhs);
+ ctx->rhs = malloc(strlen(p) + 2);
+ if (ctx->rhs)
+ {
+ *ctx->rhs = '.';
+ strcpy(ctx->rhs + 1, (*p == '.') ? p + 1 : p);
+ return 0;
+ }
+ else
+ __set_errno (ENOMEM);
+ }
+ else
+ return 0;
+ }
+ }
+ else
+ __set_errno (ENOMEM);
+
+ if (ctx->lhs)
+ free(ctx->lhs);
+ if (ctx->rhs)
+ free(ctx->rhs);
+ if (ctx)
+ free(ctx);
+ return -1;
+}
+
+/* This function deallocates the hesiod_p. */
+void hesiod_end(void *context)
+{
+ struct hesiod_p *ctx = (struct hesiod_p *) context;
+
+ free(ctx->rhs);
+ if (ctx->lhs)
+ free(ctx->lhs);
+ free(ctx);
+}
+
+/* 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[MAXDNAME], *p, *ret, **rhs_list = NULL;
+ const char *rhs;
+ int len;
+
+ strcpy(bindname, name);
+
+ /* Find the right right hand side to use, possibly truncating bindname. */
+ p = strchr(bindname, '@');
+ if (p)
+ {
+ *p++ = 0;
+ if (strchr(p, '.'))
+ rhs = name + (p - bindname);
+ else
+ {
+ rhs_list = hesiod_resolve(context, p, "rhs-extension");
+ if (rhs_list)
+ rhs = *rhs_list;
+ else
+ {
+ __set_errno (ENOENT);
+ return NULL;
+ }
+ }
+ } else
+ rhs = ctx->rhs;
+
+ /* See if we have enough room. */
+ len = strlen(bindname) + 1 + strlen(type);
+ if (ctx->lhs)
+ len += strlen(ctx->lhs) + ((ctx->lhs[0] != '.') ? 1 : 0);
+ len += strlen(rhs) + ((rhs[0] != '.') ? 1 : 0);
+ if (len > sizeof(bindname) - 1)
+ {
+ if (rhs_list)
+ hesiod_free_list(context, rhs_list);
+ __set_errno (EMSGSIZE);
+ return NULL;
+ }
+
+ /* Put together the rest of the domain. */
+ 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);
+
+ /* rhs_list is no longer needed, since we're done with rhs. */
+ if (rhs_list)
+ hesiod_free_list(context, rhs_list);
+
+ /* Make a copy of the result and return it to the caller. */
+ ret = malloc(strlen(bindname) + 1);
+ if (!ret)
+ {
+ __set_errno (ENOMEM);
+ return NULL;
+ }
+ strcpy(ret, bindname);
+ return ret;
+}
+
+/* This is the core function. Given a hesiod name and 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, **retvec;
+
+ bindname = hesiod_to_bind(context, name, type);
+ if (!bindname)
+ return NULL;
+
+ retvec = get_txt_records(ctx, ctx->classes[0], bindname);
+ if (retvec == NULL && errno == ENOENT && ctx->classes[1])
+ retvec = get_txt_records(ctx, ctx->classes[1], bindname);
+
+ free(bindname);
+ return retvec;
+}
+
+void hesiod_free_list(void *context, char **list)
+{
+ char **p;
+
+ for (p = list; *p; p++)
+ free(*p);
+ free(list);
+}
+
+/* This function parses the /etc/hesiod.conf file. Returns 0 on success,
+ * -1 on failure. On failure, it might leave values in ctx->lhs or
+ * ctx->rhs which need to be freed by the caller. */
+static int read_config_file(struct hesiod_p *ctx, const char *filename)
+{
+ char *key, *data, *p, **which;
+ char buf[MAXDNAME + 7];
+ int n;
+ FILE *fp;
+
+ /* Set default query classes. */
+ ctx->classes[0] = C_IN;
+ ctx->classes[1] = C_HS;
+
+ /* Try to open the configuration file. */
+ fp = fopen(filename, "r");
+ if (!fp)
+ {
+ /* Use compiled in default domain names. */
+ ctx->lhs = malloc(strlen(DEF_LHS) + 1);
+ ctx->rhs = malloc(strlen(DEF_RHS) + 1);
+ if (ctx->lhs && ctx->rhs)
+ {
+ strcpy(ctx->lhs, DEF_LHS);
+ strcpy(ctx->rhs, DEF_RHS);
+ return 0;
+ }
+ else
+ {
+ __set_errno (ENOMEM);
+ return -1;
+ }
+ }
+
+ ctx->lhs = NULL;
+ ctx->rhs = NULL;
+ while (fgets(buf, sizeof(buf), fp) != NULL)
+ {
+ p = buf;
+ if (*p == '#' || *p == '\n' || *p == '\r')
+ continue;
+ while(*p == ' ' || *p == '\t')
+ p++;
+ key = p;
+ while(*p != ' ' && *p != '\t' && *p != '=')
+ p++;
+ *p++ = 0;
+
+ while(isspace(*p) || *p == '=')
+ p++;
+ data = p;
+ while(!isspace(*p))
+ p++;
+ *p = 0;
+
+ if (cistrcmp(key, "lhs") == 0 || cistrcmp(key, "rhs") == 0)
+ {
+ which = (strcmp(key, "lhs") == 0) ? &ctx->lhs : &ctx->rhs;
+ *which = malloc(strlen(data) + 1);
+ if (!*which)
+ {
+ __set_errno (ENOMEM);
+ return -1;
+ }
+ strcpy(*which, data);
+ }
+ else if (cistrcmp(key, "classes") == 0)
+ {
+ n = 0;
+ while (*data && n < 2)
+ {
+ p = data;
+ while (*p && *p != ',')
+ p++;
+ if (*p)
+ *p++ = 0;
+ if (cistrcmp(data, "IN") == 0)
+ ctx->classes[n++] = C_IN;
+ else if (cistrcmp(data, "HS") == 0)
+ ctx->classes[n++] = C_HS;
+ data = p;
+ }
+ while (n < 2)
+ ctx->classes[n++] = 0;
+ }
+ }
+ fclose(fp);
+
+ if (!ctx->rhs || ctx->classes[0] == 0 || ctx->classes[0] == ctx->classes[1])
+ {
+ __set_errno (ENOEXEC);
+ return -1;
+ }
+
+ return 0;
+}
+
+/* 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 qclass,
+ const char *name)
+{
+ HEADER *hp;
+ unsigned char qbuf[PACKETSZ], abuf[MAX_HESRESP], *p, *eom, *eor;
+ char *dst, **list;
+ int ancount, qdcount, i, j, n, skip, type, class, len;
+
+ /* Make sure the resolver is initialized. */
+ if ((_res.options & RES_INIT) == 0 && res_init() == -1)
+ return NULL;
+
+ /* Construct the query. */
+ n = res_mkquery(QUERY, name, qclass, T_TXT, NULL, 0,
+ NULL, qbuf, PACKETSZ);
+ if (n < 0)
+ return NULL;
+
+ /* Send the query. */
+ n = res_send(qbuf, n, abuf, MAX_HESRESP);
+ if (n < 0)
+ {
+ __set_errno (ECONNREFUSED);
+ return NULL;
+ }
+
+ /* Parse the header of the result. */
+ hp = (HEADER *) abuf;
+ ancount = ntohs(hp->ancount);
+ qdcount = ntohs(hp->qdcount);
+ p = abuf + sizeof(HEADER);
+ eom = abuf + n;
+
+ /* Skip questions, trying to get to the answer section which follows. */
+ for (i = 0; i < qdcount; i++)
+ {
+ skip = dn_skipname(p, eom);
+ if (skip < 0 || p + skip + QFIXEDSZ > eom)
+ {
+ __set_errno (EMSGSIZE);
+ return NULL;
+ }
+ p += skip + QFIXEDSZ;
+ }
+
+ /* Allocate space for the text record answers. */
+ list = malloc((ancount + 1) * sizeof(char *));
+ if (!list)
+ {
+ __set_errno (ENOMEM);
+ return NULL;
+ }
+
+ /* Parse the answers. */
+ j = 0;
+ for (i = 0; i < ancount; i++)
+ {
+ /* Parse the header of this answer. */
+ skip = dn_skipname(p, eom);
+ if (skip < 0 || p + skip + 10 > eom)
+ break;
+ type = p[skip + 0] << 8 | p[skip + 1];
+ class = p[skip + 2] << 8 | p[skip + 3];
+ len = p[skip + 8] << 8 | p[skip + 9];
+ p += skip + 10;
+ if (p + len > eom)
+ {
+ __set_errno (EMSGSIZE);
+ break;
+ }
+
+ /* Skip entries of the wrong class and type. */
+ if (class != qclass || type != T_TXT)
+ {
+ p += len;
+ continue;
+ }
+
+ /* Allocate space for this answer. */
+ list[j] = malloc(len);
+ if (!list[j])
+ {
+ __set_errno (ENOMEM);
+ break;
+ }
+ dst = list[j++];
+
+ /* Copy answer data into the allocated area. */
+ eor = p + len;
+ while (p < eor)
+ {
+ n = (unsigned char) *p++;
+ if (p + n > eor)
+ {
+ __set_errno (EMSGSIZE);
+ break;
+ }
+ memcpy(dst, p, n);
+ p += n;
+ dst += n;
+ }
+ if (p < eor)
+ {
+ __set_errno (EMSGSIZE);
+ break;
+ }
+ *dst = 0;
+ }
+
+ /* If we didn't terminate the loop normally, something went wrong. */
+ if (i < ancount)
+ {
+ for (i = 0; i < j; i++)
+ free(list[i]);
+ free(list);
+ return NULL;
+ }
+
+ if (j == 0)
+ {
+ __set_errno (ENOENT);
+ free(list);
+ return NULL;
+ }
+
+ list[j] = NULL;
+ return list;
+}
+
+static int cistrcmp(const char *s1, const char *s2)
+{
+ while (*s1 && tolower(*s1) == tolower(*s2))
+ {
+ s1++;
+ s2++;
+ }
+ return tolower(*s1) - tolower(*s2);
+}
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