meillo@0: /* MasqMail Copyright (C) Oliver Kurth,
meillo@0:  *
meillo@0:  * This program is free software; you can redistribute it and/or modify
meillo@0:  * it under the terms of the GNU General Public License as published by
meillo@0:  * the Free Software Foundation; either version 2 of the License, or
meillo@0:  * (at your option) any later version.
meillo@10:  *
meillo@0:  * This program is distributed in the hope that it will be useful,
meillo@0:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
meillo@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
meillo@0:  * GNU General Public License for more details.
meillo@0:  *
meillo@0:  * You should have received a copy of the GNU General Public License
meillo@0:  * along with this program; if not, write to the Free Software
meillo@0:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
meillo@0:  */
meillo@0: 
meillo@0: #include <sys/types.h>
meillo@0: #include <netinet/in.h>
meillo@0: #include <arpa/nameser.h>
meillo@0: #include <resolv.h>
meillo@0: 
meillo@0: #include "masqmail.h"
meillo@0: 
meillo@0: 
meillo@0: #ifdef ENABLE_RESOLVER
meillo@0: 
meillo@0: static union {
meillo@10: 	HEADER hdr;
meillo@10: 	unsigned char buf[PACKETSZ];
meillo@0: } response;
meillo@0: static unsigned char *resp_end;
meillo@0: static unsigned char *resp_pos;
meillo@0: 
meillo@0: static int num_answers;
meillo@0: static char name[MAX_DNSNAME];
meillo@0: 
meillo@0: unsigned short rr_type;
meillo@0: unsigned short rr_dlen;
meillo@0: 
meillo@10: static unsigned short
meillo@10: getshort(unsigned char *c)
meillo@0: {
meillo@10: 	unsigned short u;
meillo@10: 	u = c[0];
meillo@10: 	return (u << 8) + c[1];
meillo@0: }
meillo@0: 
meillo@10: static int
meillo@10: dns_resolve(char *domain, int type, gboolean do_search)
meillo@0: {
meillo@10: 	int n;
meillo@10: 	int i;
meillo@207: 	int resp_len;
meillo@0: 
meillo@10: 	DEBUG(5) debugf("DNS: before res_search()\n");
meillo@10: 	if (do_search)
meillo@10: 		resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
meillo@10: 	else
meillo@10: 		resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
meillo@10: 	DEBUG(5) debugf("DBG: after res_search()\n");
meillo@0: 
meillo@10: 	if (resp_len <= 0) {
meillo@10: 		/*
meillo@10: 		   if (errno == ECONNREFUSED) return DNS_SOFT;
meillo@10: 		   if (h_errno == TRY_AGAIN) return DNS_SOFT;
meillo@10: 		   return DNS_HARD;
meillo@10: 		 */
meillo@10: 		return -1;
meillo@10: 	}
meillo@10: 	if (resp_len >= sizeof(response))
meillo@10: 		resp_len = sizeof(response);
meillo@0: 
meillo@10: 	resp_end = response.buf + resp_len;
meillo@10: 	resp_pos = response.buf + sizeof(HEADER);
meillo@10: 	n = ntohs(response.hdr.qdcount);
meillo@0: 
meillo@10: 	while (n-- > 0) {
meillo@10: 		i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
meillo@10: 		if (i < 0)
meillo@10: 			return -1;
meillo@10: 		DEBUG(5) debugf("DBG: resolve name = %s\n", name);
meillo@10: 		resp_pos += i;
meillo@10: 		i = resp_end - resp_pos;
meillo@10: 		if (i < QFIXEDSZ)
meillo@10: 			return -1;
meillo@10: 		resp_pos += QFIXEDSZ;
meillo@10: 	}
meillo@10: 	num_answers = ntohs(response.hdr.ancount);
meillo@0: 
meillo@10: 	return 0;
meillo@0: }
meillo@0: 
meillo@10: static int
meillo@10: dns_next()
meillo@0: {
meillo@10: 	int i;
meillo@0: 
meillo@10: 	if (num_answers <= 0)
meillo@10: 		return 2;
meillo@10: 	num_answers--;
meillo@0: 
meillo@10: 	if (resp_pos == resp_end)
meillo@10: 		return -1;  /* soft */
meillo@0: 
meillo@10: 	i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
meillo@10: 	if (i < 0)
meillo@10: 		return -1;  /* soft */
meillo@10: 	resp_pos += i;
meillo@0: 
meillo@10: 	i = resp_end - resp_pos;
meillo@10: 	if (i < 4 + 3 * 2)
meillo@10: 		return -1;  /* soft */
meillo@0: 
meillo@10: 	rr_type = getshort(resp_pos);
meillo@10: 	rr_dlen = getshort(resp_pos + 8);
meillo@10: 	resp_pos += 10;
meillo@10: 
meillo@10: 	return 0;
meillo@0: }
meillo@0: 
meillo@10: static int
meillo@10: dns_getip(guint32 * ip)
meillo@0: {
meillo@10: 	int ret;
meillo@0: 
meillo@10: 	if ((ret = dns_next()))
meillo@10: 		return ret;
meillo@0: 
meillo@10: 	if (rr_type == T_A) {
meillo@10: 		if (rr_dlen < 4)
meillo@10: 			return -1;  /* soft */
meillo@10: 		*ip = *(guint32 *) (resp_pos);
meillo@10: 		DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10: 		resp_pos += rr_dlen;
meillo@0: 
meillo@10: 		return 1;
meillo@10: 	}
meillo@10: 	resp_pos += rr_dlen;
meillo@10: 	return 0;
meillo@0: }
meillo@0: 
meillo@10: static int
meillo@10: dns_getmx(int *pref)
meillo@0: {
meillo@10: 	int ret;
meillo@0: 
meillo@10: 	if ((ret = dns_next()))
meillo@10: 		return ret;
meillo@0: 
meillo@10: 	if (rr_type == T_MX) {
meillo@10: 		if (rr_dlen < 3)
meillo@10: 			return -1;  /* soft */
meillo@0: 
meillo@10: 		*pref = (resp_pos[0] << 8) + resp_pos[1];
meillo@10: 		if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
meillo@10: 			return -1;
meillo@0: 
meillo@10: 		resp_pos += rr_dlen;
meillo@10: 
meillo@10: 		return 1;
meillo@10: 	}
meillo@10: 	resp_pos += rr_dlen;
meillo@10: 	return 0;
meillo@0: }
meillo@0: 
meillo@200: int
meillo@10: dns_look_ip(gchar * domain, guint32 * ip)
meillo@0: {
meillo@10: 	gchar *n = domain;
meillo@0: 
meillo@10: 	while (TRUE) {
meillo@200: 		if (dns_resolve(n, T_A, FALSE) != 0) {
meillo@200: 			return -1;
meillo@200: 		}
meillo@0: 
meillo@200: 		dns_next();
meillo@200: 		if (rr_type == T_A) {
meillo@200: 			if (rr_dlen < 4) {
meillo@200: 				return -1;  /* soft */
meillo@200: 			}
meillo@200: 			*ip = *(guint32 *) (resp_pos);
meillo@10: 
meillo@200: 			DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10: 
meillo@200: 			resp_pos += rr_dlen;
meillo@200: 			return 0;
meillo@200: 		} else if (rr_type == T_CNAME) {
meillo@200: 			if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0) {
meillo@200: 				return -1;
meillo@200: 			}
meillo@10: 
meillo@200: 			DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
meillo@200: 
meillo@200: 			resp_pos += rr_dlen;
meillo@200: 			n = name;
meillo@200: 		} else {
meillo@10: 			return -1;
meillo@200: 		}
meillo@10: 	}
meillo@0: }
meillo@0: 
meillo@10: GList*
meillo@10: resolve_dns_a(GList * list, gchar * domain)
meillo@0: {
meillo@10: 	int ret;
meillo@0: 
meillo@10: 	DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
meillo@0: 
meillo@10: 	if (dns_resolve(domain, T_A, TRUE) == 0) {
meillo@10: 		mxip_addr mxip;
meillo@10: 		while ((ret = dns_getip(&(mxip.ip))) != 2) {
meillo@10: 			if (ret == 1) {
meillo@10: 				mxip.name = g_strdup(name);
meillo@10: 				mxip.pref = 0;
meillo@10: 				list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10: 			}
meillo@10: 		}
meillo@10: 	}
meillo@10: 	return list;
meillo@0: }
meillo@0: 
meillo@10: static gint
meillo@10: _mx_sort_func(gconstpointer aa, gconstpointer bb)
meillo@0: {
meillo@10: 	const mxip_addr *a = (mxip_addr *) aa;
meillo@10: 	const mxip_addr *b = (mxip_addr *) bb;
meillo@0: 
meillo@10: 	if (a->pref == b->pref)
meillo@10: 		return a->ip - b->ip;
meillo@10: 	else
meillo@10: 		return a->pref - b->pref;
meillo@0: }
meillo@0: 
meillo@10: GList*
meillo@10: resolve_dns_mx(GList * list, gchar * domain)
meillo@0: {
meillo@10: 	GList *node;
meillo@10: 	int ret;
meillo@10: 	int cnt = 0;
meillo@0: 
meillo@10: 	DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
meillo@0: 
meillo@10: 	if (dns_resolve(domain, T_MX, TRUE) == 0) {
meillo@10: 		GList *node_next;
meillo@10: 		mxip_addr mxip;
meillo@10: 		while ((ret = dns_getmx(&(mxip.pref))) != 2) {
meillo@10: 			if (ret == 1) {
meillo@10: 				mxip.name = g_strdup(name);
meillo@10: 				mxip.ip = rand();
meillo@10: 				list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10: 				cnt++;
meillo@10: 			}
meillo@10: 		}
meillo@0: 
meillo@10: 		DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
meillo@0: 
meillo@10: 		/* to randomize sequences with equal pref values,
meillo@10: 		   we temporarily 'misused' the ip field and
meillo@10: 		   put a random number in it as a secondary sort key.
meillo@10: 		 */
meillo@10: 		list = g_list_sort(list, _mx_sort_func);
meillo@0: 
meillo@10: 		/* CNAME resolving has to be added as well. */
meillo@0: 
meillo@10: 		for (node = g_list_first(list); node != NULL; node = node_next) {
meillo@0: 
meillo@10: 			mxip_addr *p_mxip = (mxip_addr *) (node->data);
meillo@10: 			node_next = g_list_next(node);
meillo@0: 
meillo@10: 			if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
meillo@10: 				DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
meillo@10: 				list = g_list_remove_link(list, node);
meillo@10: 				g_free(node->data);
meillo@10: 				g_list_free_1(node);
meillo@10: 			}
meillo@10: 		}
meillo@10: 	}
meillo@10: 	return list;
meillo@0: }
meillo@0: 
meillo@0: #endif
meillo@0: 
meillo@0: /* now something completely different... */
meillo@0: 
meillo@10: GList*
meillo@10: resolve_byname(GList * list, gchar * domain)
meillo@0: {
meillo@10: 	struct hostent *hent;
meillo@0: 
meillo@10: 	DEBUG(5) debugf("DNS: resolve_byname entered\n");
meillo@0: 
meillo@10: 	if ((hent = gethostbyname(domain))) {
meillo@10: 		char *haddr;
meillo@10: 		int i = 0;
meillo@10: 		while ((haddr = hent->h_addr_list[i++])) {
meillo@10: 			mxip_addr mxip;
meillo@10: 			mxip.ip = *(guint32 *) (haddr);
meillo@10: 			mxip.pref = 0;
meillo@10: 			mxip.name = g_strdup(hent->h_name);
meillo@10: 			list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10: 		}
meillo@10: 	}
meillo@10: 	return list;
meillo@0: }