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@0:  * 
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: #ifdef RESOLV_TEST
meillo@0: 
meillo@0: #undef DEBUG
meillo@0: #define DEBUG(x) if(x > 0)
meillo@0: 
meillo@0: #define debugf g_print
meillo@0: #endif
meillo@0: 
meillo@0: #ifdef ENABLE_RESOLVER
meillo@0: 
meillo@0: static union {
meillo@0:   HEADER hdr;
meillo@0:   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@0: static
meillo@0: unsigned short getshort(unsigned char *c)
meillo@0: {
meillo@0:   unsigned short u;
meillo@0:   u = c[0];
meillo@0:   return (u << 8) + c[1];
meillo@0: }
meillo@0: 
meillo@0: static
meillo@0: int dns_resolve(char *domain, int type, gboolean do_search)
meillo@0: {
meillo@0:   int n;
meillo@0:   int i;
meillo@0: 
meillo@0:   int resp_len;
meillo@0:   /*errno = 0;*/
meillo@0: 
meillo@0:   /*
meillo@0:   if (!stralloc_copy(&glue,domain)) return DNS_MEM;
meillo@0:   if (!stralloc_0(&glue)) return DNS_MEM;
meillo@0:   */
meillo@0: 
meillo@0:   //  resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
meillo@0:   DEBUG(5) debugf("DNS: before res_search()\n");
meillo@0:   if(do_search)
meillo@0:     resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
meillo@0:   else
meillo@0:     resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
meillo@0:   DEBUG(5) debugf("DBG: after res_search()\n");
meillo@0: 
meillo@0:   if (resp_len <= 0){
meillo@0:     /*
meillo@0:     if (errno == ECONNREFUSED) return DNS_SOFT;
meillo@0:     if (h_errno == TRY_AGAIN) return DNS_SOFT;
meillo@0:     return DNS_HARD;
meillo@0:     */
meillo@0:     return -1;
meillo@0:   }
meillo@0:   if (resp_len >= sizeof(response))
meillo@0:     resp_len = sizeof(response);
meillo@0: 
meillo@0:   resp_end = response.buf + resp_len;
meillo@0:   resp_pos = response.buf + sizeof(HEADER);
meillo@0:   n = ntohs(response.hdr.qdcount);
meillo@0: 
meillo@0:   while (n-- > 0){
meillo@0:     i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
meillo@0:     if (i < 0)
meillo@0:       return -1;
meillo@0:     DEBUG(5) debugf("DBG: resolve name = %s\n", name);
meillo@0:     resp_pos += i;
meillo@0:     i = resp_end - resp_pos;
meillo@0:     if (i < QFIXEDSZ)
meillo@0:       return -1;
meillo@0:     resp_pos += QFIXEDSZ;
meillo@0:   }
meillo@0:   num_answers = ntohs(response.hdr.ancount);
meillo@0: 
meillo@0:   return 0;
meillo@0: }
meillo@0: 
meillo@0: static int dns_next()
meillo@0: {
meillo@0:   int i;
meillo@0: 
meillo@0:   if (num_answers <= 0) return 2;
meillo@0:   num_answers--;
meillo@0: 
meillo@0:   if (resp_pos == resp_end)
meillo@0:     return -1 /* soft */;
meillo@0: 
meillo@0:   i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
meillo@0:   if (i < 0)
meillo@0:     return -1; /* soft */
meillo@0:   resp_pos += i;
meillo@0: 
meillo@0:   i = resp_end - resp_pos;
meillo@0:   if (i < 4 + 3 * 2)
meillo@0:     return -1; /* soft */
meillo@0:    
meillo@0:   rr_type = getshort(resp_pos);
meillo@0:   rr_dlen = getshort(resp_pos + 8);
meillo@0:   resp_pos += 10;
meillo@0: 
meillo@0:   return 0;
meillo@0: }
meillo@0: 
meillo@0: static
meillo@0: int dns_getip(guint32 *ip)
meillo@0: {
meillo@0:   int ret;
meillo@0: 
meillo@0:   if((ret = dns_next())) return ret;
meillo@0: 
meillo@0:   if (rr_type == T_A){
meillo@0:     if (rr_dlen < 4)
meillo@0:       return -1; /* soft */
meillo@0:     *ip = *(guint32 *)(resp_pos);
meillo@0:     DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr*)ip));
meillo@0:     resp_pos += rr_dlen;
meillo@0: 
meillo@0:     return 1;
meillo@0:   }
meillo@0:   resp_pos += rr_dlen;
meillo@0:   return 0;
meillo@0: }
meillo@0: 
meillo@0: static
meillo@0: int dns_getmx(int *pref)
meillo@0: {
meillo@0:   int ret;
meillo@0: 
meillo@0:   if((ret = dns_next())) return ret;
meillo@0: 
meillo@0:   if (rr_type == T_MX){
meillo@0:     if (rr_dlen < 3)
meillo@0:       return -1; /* soft */
meillo@0: 
meillo@0:     *pref = (resp_pos[0] << 8) + resp_pos[1];
meillo@0:     if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
meillo@0:       return -1;
meillo@0:    
meillo@0:     resp_pos += rr_dlen;
meillo@0: 
meillo@0:     return 1;
meillo@0:   }
meillo@0:   resp_pos += rr_dlen;
meillo@0:   return 0;
meillo@0: }
meillo@0: 
meillo@0: /*
meillo@0: static
meillo@0: int dns_getname(int type)
meillo@0: {
meillo@0:   int ret;
meillo@0: 
meillo@0:   if((ret = dns_next())) return ret;
meillo@0: 
meillo@0:   if (rr_type == type){
meillo@0:     if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
meillo@0:       return -1;
meillo@0:    
meillo@0:     resp_pos += rr_dlen;
meillo@0: 
meillo@0:     return 1;
meillo@0:   }
meillo@0:   resp_pos += rr_dlen;
meillo@0:   return 0;
meillo@0: }
meillo@0: */
meillo@0: 
meillo@0: static
meillo@0: int dns_look_ip(gchar *domain, guint32 *ip)
meillo@0: {
meillo@0:   gchar *n = domain;
meillo@0: 
meillo@0:   while(TRUE){
meillo@0:     if(dns_resolve(n, T_A, FALSE) == 0){
meillo@0:       dns_next();
meillo@0:       if(rr_type == T_A){
meillo@0: 	if (rr_dlen < 4)
meillo@0: 	  return -1; /* soft */
meillo@0: 	*ip = *(guint32 *)(resp_pos);
meillo@0: 	
meillo@0: 	DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n",
meillo@0: 			inet_ntoa(*(struct in_addr*)ip));
meillo@0: 	
meillo@0: 	resp_pos += rr_dlen;
meillo@0: 	return 0;
meillo@0:       }else if(rr_type == T_CNAME){
meillo@0: 	if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
meillo@0: 	  return -1;
meillo@0: 
meillo@0: 	DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
meillo@0: 	
meillo@0: 	resp_pos += rr_dlen;
meillo@0: 	n = name;
meillo@0:       }else
meillo@0: 	return -1;
meillo@0:     }else
meillo@0:       return -1;
meillo@0:   }
meillo@0: }
meillo@0: 
meillo@0: GList *resolve_dns_a(GList *list, gchar *domain)
meillo@0: {
meillo@0:   int ret;
meillo@0: 
meillo@0:   DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
meillo@0: 
meillo@0:   if(dns_resolve(domain, T_A, TRUE) == 0){
meillo@0:     mxip_addr mxip;
meillo@0:     while((ret = dns_getip(&(mxip.ip))) != 2){
meillo@0:       if(ret == 1){
meillo@0: 	mxip.name = g_strdup(name);
meillo@0: 	mxip.pref = 0;
meillo@0: 	list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@0:       }
meillo@0:     }
meillo@0:   }
meillo@0:   return list;
meillo@0: }
meillo@0: 
meillo@0: static
meillo@0: gint _mx_sort_func(gconstpointer aa, gconstpointer bb)
meillo@0: {
meillo@0:   const mxip_addr *a = (mxip_addr *)aa;
meillo@0:   const mxip_addr *b = (mxip_addr *)bb;
meillo@0: 
meillo@0:   if(a->pref == b->pref)
meillo@0:     return a->ip - b->ip;
meillo@0:   else
meillo@0:     return a->pref - b->pref;
meillo@0: }
meillo@0: 
meillo@0: GList *resolve_dns_mx(GList *list, gchar *domain)
meillo@0: {
meillo@0:   GList *node;
meillo@0:   int ret;
meillo@0:   int cnt = 0;
meillo@0: 
meillo@0:   DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
meillo@0: 
meillo@0:   if(dns_resolve(domain, T_MX, TRUE) == 0){
meillo@0:     GList *node_next;
meillo@0:     mxip_addr mxip;
meillo@0:     while((ret = dns_getmx(&(mxip.pref))) != 2){
meillo@0:       if(ret == 1){
meillo@0: 	mxip.name = g_strdup(name);
meillo@0: 	mxip.ip = rand();
meillo@0: 	list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@0: 	cnt++;
meillo@0:       }
meillo@0:     }
meillo@0: 
meillo@0:     DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
meillo@0: 
meillo@0:     /* to randomize sequences with equal pref values,
meillo@0:        we temporarily 'misused' the ip field and
meillo@0:        put a random number in it as a secondary sort key.
meillo@0:     */
meillo@0:     list = g_list_sort(list, _mx_sort_func);
meillo@0: 
meillo@0:     /* CNAME resolving has to be added as well. */
meillo@0: 
meillo@0:     for(node = g_list_first(list);
meillo@0: 	node != NULL;
meillo@0: 	node = node_next){
meillo@0: 
meillo@0:       mxip_addr *p_mxip = (mxip_addr *)(node->data);
meillo@0:       node_next = g_list_next(node);
meillo@0: 
meillo@0:       if(dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0){
meillo@0: 	DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
meillo@0: 	list = g_list_remove_link(list, node);
meillo@0: 	g_free(node->data);
meillo@0: 	g_list_free_1(node);
meillo@0:       }
meillo@0:     }
meillo@0:   }
meillo@0:   return list;
meillo@0: }
meillo@0: 
meillo@0: #endif
meillo@0: 
meillo@0: /* now something completely different... */
meillo@0: 
meillo@0: GList *resolve_byname(GList *list, gchar *domain)
meillo@0: {
meillo@0:   struct hostent *hent;
meillo@0: 
meillo@0:   DEBUG(5) debugf("DNS: resolve_byname entered\n");
meillo@0: 
meillo@0:   if((hent = gethostbyname(domain))){
meillo@0:     char *haddr;
meillo@0:     int i = 0;
meillo@0:     while((haddr = hent->h_addr_list[i++])){
meillo@0:       mxip_addr mxip;
meillo@0:       mxip.ip = *(guint32 *)(haddr);
meillo@0:       mxip.pref = 0;
meillo@0:       mxip.name = g_strdup(hent->h_name);
meillo@0:       list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@0:     }
meillo@0:   }
meillo@0:   return list;
meillo@0: }
meillo@0: 
meillo@0: #ifdef RESOLV_TEST
meillo@0: int main(int argc, char *argv[])
meillo@0: {
meillo@0:   GList *addr_list = NULL, *node;
meillo@0: 
meillo@0:   g_print("starting res_init()\n");
meillo@0: 
meillo@0:   g_print("retrans = %d, retry = %d\n", _res.retrans, _res.retry);
meillo@0: 
meillo@0:   if(res_init() == 0){
meillo@0:     
meillo@0:     addr_list = resolve_dns_a(NULL, argv[1]);
meillo@0:     g_print("A:\n");
meillo@0: 
meillo@0:     foreach(addr_list, node){
meillo@0:       mxip_addr *p_mxip = (mxip_addr *)(node->data);
meillo@0:     
meillo@0:       printf("name = %s\n IP = %s\n",
meillo@0: 	     p_mxip->name,
meillo@0: 	     inet_ntoa(*(struct in_addr *)&(p_mxip->ip)));
meillo@0:     }
meillo@0:     addr_list = resolve_dns_mx(NULL, argv[1]);
meillo@0:     g_print("MX:\n");
meillo@0: 
meillo@0:     foreach(addr_list, node){
meillo@0:       mxip_addr *p_mxip = (mxip_addr *)(node->data);
meillo@0:     
meillo@0:       printf("name = %s\n IP = %s pref = %d\n",
meillo@0: 	     p_mxip->name,
meillo@0: 	     inet_ntoa(*(struct in_addr *)&(p_mxip->ip)),
meillo@0: 	     p_mxip->pref);
meillo@0:     }
meillo@0:     {
meillo@0:       guint32 ip;
meillo@0:       dns_look_ip(argv[1], &ip);
meillo@0:       printf("dns_look_ip: %s\n", inet_ntoa(*((struct in_addr *)(&ip))));
meillo@0:     }
meillo@0:   }else
meillo@0:     printf("res_init() failed.\n");
meillo@0:   
meillo@0: }
meillo@0: #endif