masqmail

annotate src/lookup.c @ 215:08b32edca1d5

find changesets by author, revision, files, or words in the commit message
added the contents of the old FAQ page it surely needs an update
author meillo@marmaro.de
date Mon, 19 Jul 2010 14:10:14 +0200
parents 138e66e1a61f
children 996b53a50f55
rev   line source
meillo@0 1 /* MasqMail Copyright (C) Oliver Kurth,
meillo@0 2 *
meillo@0 3 * This program is free software; you can redistribute it and/or modify
meillo@0 4 * it under the terms of the GNU General Public License as published by
meillo@0 5 * the Free Software Foundation; either version 2 of the License, or
meillo@0 6 * (at your option) any later version.
meillo@10 7 *
meillo@0 8 * This program is distributed in the hope that it will be useful,
meillo@0 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
meillo@0 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
meillo@0 11 * GNU General Public License for more details.
meillo@0 12 *
meillo@0 13 * You should have received a copy of the GNU General Public License
meillo@0 14 * along with this program; if not, write to the Free Software
meillo@0 15 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
meillo@0 16 */
meillo@0 17
meillo@0 18 #include <sys/types.h>
meillo@0 19 #include <netinet/in.h>
meillo@0 20 #include <arpa/nameser.h>
meillo@0 21 #include <resolv.h>
meillo@0 22
meillo@0 23 #include "masqmail.h"
meillo@0 24
meillo@0 25
meillo@0 26 #ifdef ENABLE_RESOLVER
meillo@0 27
meillo@0 28 static union {
meillo@10 29 HEADER hdr;
meillo@10 30 unsigned char buf[PACKETSZ];
meillo@0 31 } response;
meillo@0 32 static unsigned char *resp_end;
meillo@0 33 static unsigned char *resp_pos;
meillo@0 34
meillo@0 35 static int num_answers;
meillo@0 36 static char name[MAX_DNSNAME];
meillo@0 37
meillo@0 38 unsigned short rr_type;
meillo@0 39 unsigned short rr_dlen;
meillo@0 40
meillo@10 41 static unsigned short
meillo@10 42 getshort(unsigned char *c)
meillo@0 43 {
meillo@10 44 unsigned short u;
meillo@10 45 u = c[0];
meillo@10 46 return (u << 8) + c[1];
meillo@0 47 }
meillo@0 48
meillo@10 49 static int
meillo@10 50 dns_resolve(char *domain, int type, gboolean do_search)
meillo@0 51 {
meillo@10 52 int n;
meillo@10 53 int i;
meillo@207 54 int resp_len;
meillo@0 55
meillo@10 56 DEBUG(5) debugf("DNS: before res_search()\n");
meillo@10 57 if (do_search)
meillo@10 58 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
meillo@10 59 else
meillo@10 60 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
meillo@10 61 DEBUG(5) debugf("DBG: after res_search()\n");
meillo@0 62
meillo@10 63 if (resp_len <= 0) {
meillo@10 64 /*
meillo@10 65 if (errno == ECONNREFUSED) return DNS_SOFT;
meillo@10 66 if (h_errno == TRY_AGAIN) return DNS_SOFT;
meillo@10 67 return DNS_HARD;
meillo@10 68 */
meillo@10 69 return -1;
meillo@10 70 }
meillo@10 71 if (resp_len >= sizeof(response))
meillo@10 72 resp_len = sizeof(response);
meillo@0 73
meillo@10 74 resp_end = response.buf + resp_len;
meillo@10 75 resp_pos = response.buf + sizeof(HEADER);
meillo@10 76 n = ntohs(response.hdr.qdcount);
meillo@0 77
meillo@10 78 while (n-- > 0) {
meillo@10 79 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
meillo@10 80 if (i < 0)
meillo@10 81 return -1;
meillo@10 82 DEBUG(5) debugf("DBG: resolve name = %s\n", name);
meillo@10 83 resp_pos += i;
meillo@10 84 i = resp_end - resp_pos;
meillo@10 85 if (i < QFIXEDSZ)
meillo@10 86 return -1;
meillo@10 87 resp_pos += QFIXEDSZ;
meillo@10 88 }
meillo@10 89 num_answers = ntohs(response.hdr.ancount);
meillo@0 90
meillo@10 91 return 0;
meillo@0 92 }
meillo@0 93
meillo@10 94 static int
meillo@10 95 dns_next()
meillo@0 96 {
meillo@10 97 int i;
meillo@0 98
meillo@10 99 if (num_answers <= 0)
meillo@10 100 return 2;
meillo@10 101 num_answers--;
meillo@0 102
meillo@10 103 if (resp_pos == resp_end)
meillo@10 104 return -1; /* soft */
meillo@0 105
meillo@10 106 i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
meillo@10 107 if (i < 0)
meillo@10 108 return -1; /* soft */
meillo@10 109 resp_pos += i;
meillo@0 110
meillo@10 111 i = resp_end - resp_pos;
meillo@10 112 if (i < 4 + 3 * 2)
meillo@10 113 return -1; /* soft */
meillo@0 114
meillo@10 115 rr_type = getshort(resp_pos);
meillo@10 116 rr_dlen = getshort(resp_pos + 8);
meillo@10 117 resp_pos += 10;
meillo@10 118
meillo@10 119 return 0;
meillo@0 120 }
meillo@0 121
meillo@10 122 static int
meillo@10 123 dns_getip(guint32 * ip)
meillo@0 124 {
meillo@10 125 int ret;
meillo@0 126
meillo@10 127 if ((ret = dns_next()))
meillo@10 128 return ret;
meillo@0 129
meillo@10 130 if (rr_type == T_A) {
meillo@10 131 if (rr_dlen < 4)
meillo@10 132 return -1; /* soft */
meillo@10 133 *ip = *(guint32 *) (resp_pos);
meillo@10 134 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10 135 resp_pos += rr_dlen;
meillo@0 136
meillo@10 137 return 1;
meillo@10 138 }
meillo@10 139 resp_pos += rr_dlen;
meillo@10 140 return 0;
meillo@0 141 }
meillo@0 142
meillo@10 143 static int
meillo@10 144 dns_getmx(int *pref)
meillo@0 145 {
meillo@10 146 int ret;
meillo@0 147
meillo@10 148 if ((ret = dns_next()))
meillo@10 149 return ret;
meillo@0 150
meillo@10 151 if (rr_type == T_MX) {
meillo@10 152 if (rr_dlen < 3)
meillo@10 153 return -1; /* soft */
meillo@0 154
meillo@10 155 *pref = (resp_pos[0] << 8) + resp_pos[1];
meillo@10 156 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
meillo@10 157 return -1;
meillo@0 158
meillo@10 159 resp_pos += rr_dlen;
meillo@10 160
meillo@10 161 return 1;
meillo@10 162 }
meillo@10 163 resp_pos += rr_dlen;
meillo@10 164 return 0;
meillo@0 165 }
meillo@0 166
meillo@200 167 int
meillo@10 168 dns_look_ip(gchar * domain, guint32 * ip)
meillo@0 169 {
meillo@10 170 gchar *n = domain;
meillo@0 171
meillo@10 172 while (TRUE) {
meillo@200 173 if (dns_resolve(n, T_A, FALSE) != 0) {
meillo@200 174 return -1;
meillo@200 175 }
meillo@0 176
meillo@200 177 dns_next();
meillo@200 178 if (rr_type == T_A) {
meillo@200 179 if (rr_dlen < 4) {
meillo@200 180 return -1; /* soft */
meillo@200 181 }
meillo@200 182 *ip = *(guint32 *) (resp_pos);
meillo@10 183
meillo@200 184 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10 185
meillo@200 186 resp_pos += rr_dlen;
meillo@200 187 return 0;
meillo@200 188 } else if (rr_type == T_CNAME) {
meillo@200 189 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0) {
meillo@200 190 return -1;
meillo@200 191 }
meillo@10 192
meillo@200 193 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
meillo@200 194
meillo@200 195 resp_pos += rr_dlen;
meillo@200 196 n = name;
meillo@200 197 } else {
meillo@10 198 return -1;
meillo@200 199 }
meillo@10 200 }
meillo@0 201 }
meillo@0 202
meillo@10 203 GList*
meillo@10 204 resolve_dns_a(GList * list, gchar * domain)
meillo@0 205 {
meillo@10 206 int ret;
meillo@0 207
meillo@10 208 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
meillo@0 209
meillo@10 210 if (dns_resolve(domain, T_A, TRUE) == 0) {
meillo@10 211 mxip_addr mxip;
meillo@10 212 while ((ret = dns_getip(&(mxip.ip))) != 2) {
meillo@10 213 if (ret == 1) {
meillo@10 214 mxip.name = g_strdup(name);
meillo@10 215 mxip.pref = 0;
meillo@10 216 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 217 }
meillo@10 218 }
meillo@10 219 }
meillo@10 220 return list;
meillo@0 221 }
meillo@0 222
meillo@10 223 static gint
meillo@10 224 _mx_sort_func(gconstpointer aa, gconstpointer bb)
meillo@0 225 {
meillo@10 226 const mxip_addr *a = (mxip_addr *) aa;
meillo@10 227 const mxip_addr *b = (mxip_addr *) bb;
meillo@0 228
meillo@10 229 if (a->pref == b->pref)
meillo@10 230 return a->ip - b->ip;
meillo@10 231 else
meillo@10 232 return a->pref - b->pref;
meillo@0 233 }
meillo@0 234
meillo@10 235 GList*
meillo@10 236 resolve_dns_mx(GList * list, gchar * domain)
meillo@0 237 {
meillo@10 238 GList *node;
meillo@10 239 int ret;
meillo@10 240 int cnt = 0;
meillo@0 241
meillo@10 242 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
meillo@0 243
meillo@10 244 if (dns_resolve(domain, T_MX, TRUE) == 0) {
meillo@10 245 GList *node_next;
meillo@10 246 mxip_addr mxip;
meillo@10 247 while ((ret = dns_getmx(&(mxip.pref))) != 2) {
meillo@10 248 if (ret == 1) {
meillo@10 249 mxip.name = g_strdup(name);
meillo@10 250 mxip.ip = rand();
meillo@10 251 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 252 cnt++;
meillo@10 253 }
meillo@10 254 }
meillo@0 255
meillo@10 256 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
meillo@0 257
meillo@10 258 /* to randomize sequences with equal pref values,
meillo@10 259 we temporarily 'misused' the ip field and
meillo@10 260 put a random number in it as a secondary sort key.
meillo@10 261 */
meillo@10 262 list = g_list_sort(list, _mx_sort_func);
meillo@0 263
meillo@10 264 /* CNAME resolving has to be added as well. */
meillo@0 265
meillo@10 266 for (node = g_list_first(list); node != NULL; node = node_next) {
meillo@0 267
meillo@10 268 mxip_addr *p_mxip = (mxip_addr *) (node->data);
meillo@10 269 node_next = g_list_next(node);
meillo@0 270
meillo@10 271 if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
meillo@10 272 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
meillo@10 273 list = g_list_remove_link(list, node);
meillo@10 274 g_free(node->data);
meillo@10 275 g_list_free_1(node);
meillo@10 276 }
meillo@10 277 }
meillo@10 278 }
meillo@10 279 return list;
meillo@0 280 }
meillo@0 281
meillo@0 282 #endif
meillo@0 283
meillo@0 284 /* now something completely different... */
meillo@0 285
meillo@10 286 GList*
meillo@10 287 resolve_byname(GList * list, gchar * domain)
meillo@0 288 {
meillo@10 289 struct hostent *hent;
meillo@0 290
meillo@10 291 DEBUG(5) debugf("DNS: resolve_byname entered\n");
meillo@0 292
meillo@10 293 if ((hent = gethostbyname(domain))) {
meillo@10 294 char *haddr;
meillo@10 295 int i = 0;
meillo@10 296 while ((haddr = hent->h_addr_list[i++])) {
meillo@10 297 mxip_addr mxip;
meillo@10 298 mxip.ip = *(guint32 *) (haddr);
meillo@10 299 mxip.pref = 0;
meillo@10 300 mxip.name = g_strdup(hent->h_name);
meillo@10 301 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 302 }
meillo@10 303 }
meillo@10 304 return list;
meillo@0 305 }