masqmail

annotate src/lookup.c @ 366:41958685480d

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Switched to `type *name' style Andrew Koenig's ``C Traps and Pitfalls'' (Ch.2.1) convinced me that it is best to go with the way C had been designed. The ``declaration reflects use'' concept conflicts with a ``type* name'' notation. Hence I switched.
author markus schnalke <meillo@marmaro.de>
date Thu, 22 Sep 2011 15:07:40 +0200
parents 996b53a50f55
children b27f66555ba8
rev   line source
meillo@224 1 /* MasqMail
meillo@224 2 * Copyright (C) Oliver Kurth
meillo@224 3 * Copyright (C) markus schnalke <meillo@marmaro.de>
meillo@0 4 *
meillo@0 5 * This program is free software; you can redistribute it and/or modify
meillo@0 6 * it under the terms of the GNU General Public License as published by
meillo@0 7 * the Free Software Foundation; either version 2 of the License, or
meillo@0 8 * (at your option) any later version.
meillo@10 9 *
meillo@0 10 * This program is distributed in the hope that it will be useful,
meillo@0 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
meillo@0 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
meillo@0 13 * GNU General Public License for more details.
meillo@0 14 *
meillo@0 15 * You should have received a copy of the GNU General Public License
meillo@0 16 * along with this program; if not, write to the Free Software
meillo@0 17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
meillo@0 18 */
meillo@0 19
meillo@0 20 #include <sys/types.h>
meillo@0 21 #include <netinet/in.h>
meillo@0 22 #include <arpa/nameser.h>
meillo@0 23 #include <resolv.h>
meillo@0 24
meillo@0 25 #include "masqmail.h"
meillo@0 26
meillo@0 27
meillo@0 28 #ifdef ENABLE_RESOLVER
meillo@0 29
meillo@0 30 static union {
meillo@10 31 HEADER hdr;
meillo@10 32 unsigned char buf[PACKETSZ];
meillo@0 33 } response;
meillo@0 34 static unsigned char *resp_end;
meillo@0 35 static unsigned char *resp_pos;
meillo@0 36
meillo@0 37 static int num_answers;
meillo@0 38 static char name[MAX_DNSNAME];
meillo@0 39
meillo@0 40 unsigned short rr_type;
meillo@0 41 unsigned short rr_dlen;
meillo@0 42
meillo@10 43 static unsigned short
meillo@10 44 getshort(unsigned char *c)
meillo@0 45 {
meillo@10 46 unsigned short u;
meillo@10 47 u = c[0];
meillo@10 48 return (u << 8) + c[1];
meillo@0 49 }
meillo@0 50
meillo@10 51 static int
meillo@10 52 dns_resolve(char *domain, int type, gboolean do_search)
meillo@0 53 {
meillo@10 54 int n;
meillo@10 55 int i;
meillo@207 56 int resp_len;
meillo@0 57
meillo@10 58 DEBUG(5) debugf("DNS: before res_search()\n");
meillo@10 59 if (do_search)
meillo@10 60 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
meillo@10 61 else
meillo@10 62 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
meillo@10 63 DEBUG(5) debugf("DBG: after res_search()\n");
meillo@0 64
meillo@10 65 if (resp_len <= 0) {
meillo@10 66 /*
meillo@10 67 if (errno == ECONNREFUSED) return DNS_SOFT;
meillo@10 68 if (h_errno == TRY_AGAIN) return DNS_SOFT;
meillo@10 69 return DNS_HARD;
meillo@10 70 */
meillo@10 71 return -1;
meillo@10 72 }
meillo@10 73 if (resp_len >= sizeof(response))
meillo@10 74 resp_len = sizeof(response);
meillo@0 75
meillo@10 76 resp_end = response.buf + resp_len;
meillo@10 77 resp_pos = response.buf + sizeof(HEADER);
meillo@10 78 n = ntohs(response.hdr.qdcount);
meillo@0 79
meillo@10 80 while (n-- > 0) {
meillo@10 81 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
meillo@10 82 if (i < 0)
meillo@10 83 return -1;
meillo@10 84 DEBUG(5) debugf("DBG: resolve name = %s\n", name);
meillo@10 85 resp_pos += i;
meillo@10 86 i = resp_end - resp_pos;
meillo@10 87 if (i < QFIXEDSZ)
meillo@10 88 return -1;
meillo@10 89 resp_pos += QFIXEDSZ;
meillo@10 90 }
meillo@10 91 num_answers = ntohs(response.hdr.ancount);
meillo@0 92
meillo@10 93 return 0;
meillo@0 94 }
meillo@0 95
meillo@10 96 static int
meillo@10 97 dns_next()
meillo@0 98 {
meillo@10 99 int i;
meillo@0 100
meillo@10 101 if (num_answers <= 0)
meillo@10 102 return 2;
meillo@10 103 num_answers--;
meillo@0 104
meillo@10 105 if (resp_pos == resp_end)
meillo@10 106 return -1; /* soft */
meillo@0 107
meillo@10 108 i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
meillo@10 109 if (i < 0)
meillo@10 110 return -1; /* soft */
meillo@10 111 resp_pos += i;
meillo@0 112
meillo@10 113 i = resp_end - resp_pos;
meillo@10 114 if (i < 4 + 3 * 2)
meillo@10 115 return -1; /* soft */
meillo@0 116
meillo@10 117 rr_type = getshort(resp_pos);
meillo@10 118 rr_dlen = getshort(resp_pos + 8);
meillo@10 119 resp_pos += 10;
meillo@10 120
meillo@10 121 return 0;
meillo@0 122 }
meillo@0 123
meillo@10 124 static int
meillo@366 125 dns_getip(guint32 *ip)
meillo@0 126 {
meillo@10 127 int ret;
meillo@0 128
meillo@10 129 if ((ret = dns_next()))
meillo@10 130 return ret;
meillo@0 131
meillo@10 132 if (rr_type == T_A) {
meillo@10 133 if (rr_dlen < 4)
meillo@10 134 return -1; /* soft */
meillo@10 135 *ip = *(guint32 *) (resp_pos);
meillo@10 136 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10 137 resp_pos += rr_dlen;
meillo@0 138
meillo@10 139 return 1;
meillo@10 140 }
meillo@10 141 resp_pos += rr_dlen;
meillo@10 142 return 0;
meillo@0 143 }
meillo@0 144
meillo@10 145 static int
meillo@10 146 dns_getmx(int *pref)
meillo@0 147 {
meillo@10 148 int ret;
meillo@0 149
meillo@10 150 if ((ret = dns_next()))
meillo@10 151 return ret;
meillo@0 152
meillo@10 153 if (rr_type == T_MX) {
meillo@10 154 if (rr_dlen < 3)
meillo@10 155 return -1; /* soft */
meillo@0 156
meillo@10 157 *pref = (resp_pos[0] << 8) + resp_pos[1];
meillo@10 158 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
meillo@10 159 return -1;
meillo@0 160
meillo@10 161 resp_pos += rr_dlen;
meillo@10 162
meillo@10 163 return 1;
meillo@10 164 }
meillo@10 165 resp_pos += rr_dlen;
meillo@10 166 return 0;
meillo@0 167 }
meillo@0 168
meillo@200 169 int
meillo@366 170 dns_look_ip(gchar *domain, guint32 *ip)
meillo@0 171 {
meillo@10 172 gchar *n = domain;
meillo@0 173
meillo@10 174 while (TRUE) {
meillo@200 175 if (dns_resolve(n, T_A, FALSE) != 0) {
meillo@200 176 return -1;
meillo@200 177 }
meillo@0 178
meillo@200 179 dns_next();
meillo@200 180 if (rr_type == T_A) {
meillo@200 181 if (rr_dlen < 4) {
meillo@200 182 return -1; /* soft */
meillo@200 183 }
meillo@200 184 *ip = *(guint32 *) (resp_pos);
meillo@10 185
meillo@200 186 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
meillo@10 187
meillo@200 188 resp_pos += rr_dlen;
meillo@200 189 return 0;
meillo@200 190 } else if (rr_type == T_CNAME) {
meillo@200 191 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0) {
meillo@200 192 return -1;
meillo@200 193 }
meillo@10 194
meillo@200 195 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
meillo@200 196
meillo@200 197 resp_pos += rr_dlen;
meillo@200 198 n = name;
meillo@200 199 } else {
meillo@10 200 return -1;
meillo@200 201 }
meillo@10 202 }
meillo@0 203 }
meillo@0 204
meillo@10 205 GList*
meillo@366 206 resolve_dns_a(GList *list, gchar *domain)
meillo@0 207 {
meillo@10 208 int ret;
meillo@0 209
meillo@10 210 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
meillo@0 211
meillo@10 212 if (dns_resolve(domain, T_A, TRUE) == 0) {
meillo@10 213 mxip_addr mxip;
meillo@10 214 while ((ret = dns_getip(&(mxip.ip))) != 2) {
meillo@10 215 if (ret == 1) {
meillo@10 216 mxip.name = g_strdup(name);
meillo@10 217 mxip.pref = 0;
meillo@10 218 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 219 }
meillo@10 220 }
meillo@10 221 }
meillo@10 222 return list;
meillo@0 223 }
meillo@0 224
meillo@10 225 static gint
meillo@10 226 _mx_sort_func(gconstpointer aa, gconstpointer bb)
meillo@0 227 {
meillo@10 228 const mxip_addr *a = (mxip_addr *) aa;
meillo@10 229 const mxip_addr *b = (mxip_addr *) bb;
meillo@0 230
meillo@10 231 if (a->pref == b->pref)
meillo@10 232 return a->ip - b->ip;
meillo@10 233 else
meillo@10 234 return a->pref - b->pref;
meillo@0 235 }
meillo@0 236
meillo@10 237 GList*
meillo@366 238 resolve_dns_mx(GList *list, gchar *domain)
meillo@0 239 {
meillo@10 240 GList *node;
meillo@10 241 int ret;
meillo@10 242 int cnt = 0;
meillo@0 243
meillo@10 244 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
meillo@0 245
meillo@10 246 if (dns_resolve(domain, T_MX, TRUE) == 0) {
meillo@10 247 GList *node_next;
meillo@10 248 mxip_addr mxip;
meillo@10 249 while ((ret = dns_getmx(&(mxip.pref))) != 2) {
meillo@10 250 if (ret == 1) {
meillo@10 251 mxip.name = g_strdup(name);
meillo@10 252 mxip.ip = rand();
meillo@10 253 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 254 cnt++;
meillo@10 255 }
meillo@10 256 }
meillo@0 257
meillo@10 258 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
meillo@0 259
meillo@10 260 /* to randomize sequences with equal pref values,
meillo@10 261 we temporarily 'misused' the ip field and
meillo@10 262 put a random number in it as a secondary sort key.
meillo@10 263 */
meillo@10 264 list = g_list_sort(list, _mx_sort_func);
meillo@0 265
meillo@10 266 /* CNAME resolving has to be added as well. */
meillo@0 267
meillo@10 268 for (node = g_list_first(list); node != NULL; node = node_next) {
meillo@0 269
meillo@10 270 mxip_addr *p_mxip = (mxip_addr *) (node->data);
meillo@10 271 node_next = g_list_next(node);
meillo@0 272
meillo@10 273 if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
meillo@10 274 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
meillo@10 275 list = g_list_remove_link(list, node);
meillo@10 276 g_free(node->data);
meillo@10 277 g_list_free_1(node);
meillo@10 278 }
meillo@10 279 }
meillo@10 280 }
meillo@10 281 return list;
meillo@0 282 }
meillo@0 283
meillo@0 284 #endif
meillo@0 285
meillo@0 286 /* now something completely different... */
meillo@0 287
meillo@10 288 GList*
meillo@366 289 resolve_byname(GList *list, gchar *domain)
meillo@0 290 {
meillo@10 291 struct hostent *hent;
meillo@0 292
meillo@10 293 DEBUG(5) debugf("DNS: resolve_byname entered\n");
meillo@0 294
meillo@10 295 if ((hent = gethostbyname(domain))) {
meillo@10 296 char *haddr;
meillo@10 297 int i = 0;
meillo@10 298 while ((haddr = hent->h_addr_list[i++])) {
meillo@10 299 mxip_addr mxip;
meillo@10 300 mxip.ip = *(guint32 *) (haddr);
meillo@10 301 mxip.pref = 0;
meillo@10 302 mxip.name = g_strdup(hent->h_name);
meillo@10 303 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
meillo@10 304 }
meillo@10 305 }
meillo@10 306 return list;
meillo@0 307 }