masqmail
view src/lookup.c @ 407:164468dd0953
Minor refactoring.
| author | markus schnalke <meillo@marmaro.de> |
|---|---|
| date | Wed, 29 Feb 2012 10:37:21 +0100 |
| parents | 41958685480d |
| children |
line source
1 /*
2 ** MasqMail
3 ** Copyright (C) Oliver Kurth
4 ** Copyright (C) markus schnalke <meillo@marmaro.de>
5 **
6 ** This program is free software; you can redistribute it and/or modify
7 ** it under the terms of the GNU General Public License as published by
8 ** the Free Software Foundation; either version 2 of the License, or
9 ** (at your option) any later version.
10 **
11 ** This program is distributed in the hope that it will be useful,
12 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
13 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ** GNU General Public License for more details.
15 **
16 ** You should have received a copy of the GNU General Public License
17 ** along with this program; if not, write to the Free Software
18 ** Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
21 #include <sys/types.h>
22 #include <netinet/in.h>
23 #include <arpa/nameser.h>
24 #include <resolv.h>
26 #include "masqmail.h"
29 #ifdef ENABLE_RESOLVER
31 static union {
32 HEADER hdr;
33 unsigned char buf[PACKETSZ];
34 } response;
35 static unsigned char *resp_end;
36 static unsigned char *resp_pos;
38 static int num_answers;
39 static char name[MAX_DNSNAME];
41 unsigned short rr_type;
42 unsigned short rr_dlen;
44 static unsigned short
45 getshort(unsigned char *c)
46 {
47 unsigned short u;
48 u = c[0];
49 return (u << 8) + c[1];
50 }
52 static int
53 dns_resolve(char *domain, int type, gboolean do_search)
54 {
55 int n;
56 int i;
57 int resp_len;
59 DEBUG(5) debugf("DNS: before res_search()\n");
60 if (do_search)
61 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
62 else
63 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
64 DEBUG(5) debugf("DBG: after res_search()\n");
66 if (resp_len <= 0) {
67 /*
68 ** if (errno == ECONNREFUSED) return DNS_SOFT;
69 ** if (h_errno == TRY_AGAIN) return DNS_SOFT;
70 ** return DNS_HARD;
71 */
72 return -1;
73 }
74 if (resp_len >= sizeof(response))
75 resp_len = sizeof(response);
77 resp_end = response.buf + resp_len;
78 resp_pos = response.buf + sizeof(HEADER);
79 n = ntohs(response.hdr.qdcount);
81 while (n-- > 0) {
82 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
83 if (i < 0)
84 return -1;
85 DEBUG(5) debugf("DBG: resolve name = %s\n", name);
86 resp_pos += i;
87 i = resp_end - resp_pos;
88 if (i < QFIXEDSZ)
89 return -1;
90 resp_pos += QFIXEDSZ;
91 }
92 num_answers = ntohs(response.hdr.ancount);
94 return 0;
95 }
97 static int
98 dns_next()
99 {
100 int i;
102 if (num_answers <= 0)
103 return 2;
104 num_answers--;
106 if (resp_pos == resp_end)
107 return -1; /* soft */
109 i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
110 if (i < 0)
111 return -1; /* soft */
112 resp_pos += i;
114 i = resp_end - resp_pos;
115 if (i < 4 + 3 * 2)
116 return -1; /* soft */
118 rr_type = getshort(resp_pos);
119 rr_dlen = getshort(resp_pos + 8);
120 resp_pos += 10;
122 return 0;
123 }
125 static int
126 dns_getip(guint32 *ip)
127 {
128 int ret;
130 if ((ret = dns_next()))
131 return ret;
133 if (rr_type == T_A) {
134 if (rr_dlen < 4)
135 return -1; /* soft */
136 *ip = *(guint32 *) (resp_pos);
137 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
138 resp_pos += rr_dlen;
140 return 1;
141 }
142 resp_pos += rr_dlen;
143 return 0;
144 }
146 static int
147 dns_getmx(int *pref)
148 {
149 int ret;
151 if ((ret = dns_next()))
152 return ret;
154 if (rr_type == T_MX) {
155 if (rr_dlen < 3)
156 return -1; /* soft */
158 *pref = (resp_pos[0] << 8) + resp_pos[1];
159 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
160 return -1;
162 resp_pos += rr_dlen;
164 return 1;
165 }
166 resp_pos += rr_dlen;
167 return 0;
168 }
170 int
171 dns_look_ip(gchar *domain, guint32 *ip)
172 {
173 gchar *n = domain;
175 while (TRUE) {
176 if (dns_resolve(n, T_A, FALSE) != 0) {
177 return -1;
178 }
180 dns_next();
181 if (rr_type == T_A) {
182 if (rr_dlen < 4) {
183 return -1; /* soft */
184 }
185 *ip = *(guint32 *) (resp_pos);
187 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
189 resp_pos += rr_dlen;
190 return 0;
191 } else if (rr_type == T_CNAME) {
192 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0) {
193 return -1;
194 }
196 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
198 resp_pos += rr_dlen;
199 n = name;
200 } else {
201 return -1;
202 }
203 }
204 }
206 GList*
207 resolve_dns_a(GList *list, gchar *domain)
208 {
209 int ret;
211 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
213 if (dns_resolve(domain, T_A, TRUE) == 0) {
214 mxip_addr mxip;
215 while ((ret = dns_getip(&(mxip.ip))) != 2) {
216 if (ret == 1) {
217 mxip.name = g_strdup(name);
218 mxip.pref = 0;
219 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
220 }
221 }
222 }
223 return list;
224 }
226 static gint
227 _mx_sort_func(gconstpointer aa, gconstpointer bb)
228 {
229 const mxip_addr *a = (mxip_addr *) aa;
230 const mxip_addr *b = (mxip_addr *) bb;
232 if (a->pref == b->pref)
233 return a->ip - b->ip;
234 else
235 return a->pref - b->pref;
236 }
238 GList*
239 resolve_dns_mx(GList *list, gchar *domain)
240 {
241 GList *node;
242 int ret;
243 int cnt = 0;
245 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
247 if (dns_resolve(domain, T_MX, TRUE) == 0) {
248 GList *node_next;
249 mxip_addr mxip;
250 while ((ret = dns_getmx(&(mxip.pref))) != 2) {
251 if (ret == 1) {
252 mxip.name = g_strdup(name);
253 mxip.ip = rand();
254 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
255 cnt++;
256 }
257 }
259 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
261 /*
262 ** to randomize sequences with equal pref values,
263 ** we temporarily 'misused' the ip field and
264 ** put a random number in it as a secondary sort key.
265 */
266 list = g_list_sort(list, _mx_sort_func);
268 /* CNAME resolving has to be added as well. */
270 for (node = g_list_first(list); node != NULL; node = node_next) {
272 mxip_addr *p_mxip = (mxip_addr *) (node->data);
273 node_next = g_list_next(node);
275 if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
276 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
277 list = g_list_remove_link(list, node);
278 g_free(node->data);
279 g_list_free_1(node);
280 }
281 }
282 }
283 return list;
284 }
286 #endif
288 /* now something completely different... */
290 GList*
291 resolve_byname(GList *list, gchar *domain)
292 {
293 struct hostent *hent;
295 DEBUG(5) debugf("DNS: resolve_byname entered\n");
297 if ((hent = gethostbyname(domain))) {
298 char *haddr;
299 int i = 0;
300 while ((haddr = hent->h_addr_list[i++])) {
301 mxip_addr mxip;
302 mxip.ip = *(guint32 *) (haddr);
303 mxip.pref = 0;
304 mxip.name = g_strdup(hent->h_name);
305 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
306 }
307 }
308 return list;
309 }