masqmail

view src/lookup.c @ 56:f6a6f55b7b9e

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added old manual from the old website it is dated May/July 2000
author meillo@marmaro.de
date Sat, 29 May 2010 21:51:13 +0200
parents 26e34ae9a3e3
children 116b0269c934
line source
1 /* MasqMail Copyright (C) Oliver Kurth,
2 *
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
16 */
17
18 #include <sys/types.h>
19 #include <netinet/in.h>
20 #include <arpa/nameser.h>
21 #include <resolv.h>
22
23 #include "masqmail.h"
24
25 #ifdef RESOLV_TEST
26 #undef DEBUG
27 #define DEBUG(x) if(x > 0)
28 #define debugf g_print
29 #endif
30
31 #ifdef ENABLE_RESOLVER
32
33 static union {
34 HEADER hdr;
35 unsigned char buf[PACKETSZ];
36 } response;
37 static unsigned char *resp_end;
38 static unsigned char *resp_pos;
39
40 static int num_answers;
41 static char name[MAX_DNSNAME];
42
43 unsigned short rr_type;
44 unsigned short rr_dlen;
45
46 static unsigned short
47 getshort(unsigned char *c)
48 {
49 unsigned short u;
50 u = c[0];
51 return (u << 8) + c[1];
52 }
53
54 static int
55 dns_resolve(char *domain, int type, gboolean do_search)
56 {
57 int n;
58 int i;
59
60 int resp_len;
61 /*errno = 0; */
62
63 /*
64 if (!stralloc_copy(&glue,domain)) return DNS_MEM;
65 if (!stralloc_0(&glue)) return DNS_MEM;
66 */
67
68 // resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
69 DEBUG(5) debugf("DNS: before res_search()\n");
70 if (do_search)
71 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));
72 else
73 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));
74 DEBUG(5) debugf("DBG: after res_search()\n");
75
76 if (resp_len <= 0) {
77 /*
78 if (errno == ECONNREFUSED) return DNS_SOFT;
79 if (h_errno == TRY_AGAIN) return DNS_SOFT;
80 return DNS_HARD;
81 */
82 return -1;
83 }
84 if (resp_len >= sizeof(response))
85 resp_len = sizeof(response);
86
87 resp_end = response.buf + resp_len;
88 resp_pos = response.buf + sizeof(HEADER);
89 n = ntohs(response.hdr.qdcount);
90
91 while (n-- > 0) {
92 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);
93 if (i < 0)
94 return -1;
95 DEBUG(5) debugf("DBG: resolve name = %s\n", name);
96 resp_pos += i;
97 i = resp_end - resp_pos;
98 if (i < QFIXEDSZ)
99 return -1;
100 resp_pos += QFIXEDSZ;
101 }
102 num_answers = ntohs(response.hdr.ancount);
103
104 return 0;
105 }
106
107 static int
108 dns_next()
109 {
110 int i;
111
112 if (num_answers <= 0)
113 return 2;
114 num_answers--;
115
116 if (resp_pos == resp_end)
117 return -1; /* soft */
118
119 i = dn_expand(response.buf, resp_end, resp_pos, name, 256);
120 if (i < 0)
121 return -1; /* soft */
122 resp_pos += i;
123
124 i = resp_end - resp_pos;
125 if (i < 4 + 3 * 2)
126 return -1; /* soft */
127
128 rr_type = getshort(resp_pos);
129 rr_dlen = getshort(resp_pos + 8);
130 resp_pos += 10;
131
132 return 0;
133 }
134
135 static int
136 dns_getip(guint32 * ip)
137 {
138 int ret;
139
140 if ((ret = dns_next()))
141 return ret;
142
143 if (rr_type == T_A) {
144 if (rr_dlen < 4)
145 return -1; /* soft */
146 *ip = *(guint32 *) (resp_pos);
147 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
148 resp_pos += rr_dlen;
149
150 return 1;
151 }
152 resp_pos += rr_dlen;
153 return 0;
154 }
155
156 static int
157 dns_getmx(int *pref)
158 {
159 int ret;
160
161 if ((ret = dns_next()))
162 return ret;
163
164 if (rr_type == T_MX) {
165 if (rr_dlen < 3)
166 return -1; /* soft */
167
168 *pref = (resp_pos[0] << 8) + resp_pos[1];
169 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)
170 return -1;
171
172 resp_pos += rr_dlen;
173
174 return 1;
175 }
176 resp_pos += rr_dlen;
177 return 0;
178 }
179
180 /*
181 static int
182 dns_getname(int type)
183 {
184 int ret;
185
186 if((ret = dns_next())) return ret;
187
188 if (rr_type == type){
189 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
190 return -1;
191
192 resp_pos += rr_dlen;
193
194 return 1;
195 }
196 resp_pos += rr_dlen;
197 return 0;
198 }
199 */
200
201 static int
202 dns_look_ip(gchar * domain, guint32 * ip)
203 {
204 gchar *n = domain;
205
206 while (TRUE) {
207 if (dns_resolve(n, T_A, FALSE) == 0) {
208 dns_next();
209 if (rr_type == T_A) {
210 if (rr_dlen < 4)
211 return -1; /* soft */
212 *ip = *(guint32 *) (resp_pos);
213
214 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n", inet_ntoa(*(struct in_addr *) ip));
215
216 resp_pos += rr_dlen;
217 return 0;
218 } else if (rr_type == T_CNAME) {
219 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)
220 return -1;
221
222 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);
223
224 resp_pos += rr_dlen;
225 n = name;
226 } else
227 return -1;
228 } else
229 return -1;
230 }
231 }
232
233 GList*
234 resolve_dns_a(GList * list, gchar * domain)
235 {
236 int ret;
237
238 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");
239
240 if (dns_resolve(domain, T_A, TRUE) == 0) {
241 mxip_addr mxip;
242 while ((ret = dns_getip(&(mxip.ip))) != 2) {
243 if (ret == 1) {
244 mxip.name = g_strdup(name);
245 mxip.pref = 0;
246 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
247 }
248 }
249 }
250 return list;
251 }
252
253 static gint
254 _mx_sort_func(gconstpointer aa, gconstpointer bb)
255 {
256 const mxip_addr *a = (mxip_addr *) aa;
257 const mxip_addr *b = (mxip_addr *) bb;
258
259 if (a->pref == b->pref)
260 return a->ip - b->ip;
261 else
262 return a->pref - b->pref;
263 }
264
265 GList*
266 resolve_dns_mx(GList * list, gchar * domain)
267 {
268 GList *node;
269 int ret;
270 int cnt = 0;
271
272 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");
273
274 if (dns_resolve(domain, T_MX, TRUE) == 0) {
275 GList *node_next;
276 mxip_addr mxip;
277 while ((ret = dns_getmx(&(mxip.pref))) != 2) {
278 if (ret == 1) {
279 mxip.name = g_strdup(name);
280 mxip.ip = rand();
281 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
282 cnt++;
283 }
284 }
285
286 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);
287
288 /* to randomize sequences with equal pref values,
289 we temporarily 'misused' the ip field and
290 put a random number in it as a secondary sort key.
291 */
292 list = g_list_sort(list, _mx_sort_func);
293
294 /* CNAME resolving has to be added as well. */
295
296 for (node = g_list_first(list); node != NULL; node = node_next) {
297
298 mxip_addr *p_mxip = (mxip_addr *) (node->data);
299 node_next = g_list_next(node);
300
301 if (dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0) {
302 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);
303 list = g_list_remove_link(list, node);
304 g_free(node->data);
305 g_list_free_1(node);
306 }
307 }
308 }
309 return list;
310 }
311
312 #endif
313
314 /* now something completely different... */
315
316 GList*
317 resolve_byname(GList * list, gchar * domain)
318 {
319 struct hostent *hent;
320
321 DEBUG(5) debugf("DNS: resolve_byname entered\n");
322
323 if ((hent = gethostbyname(domain))) {
324 char *haddr;
325 int i = 0;
326 while ((haddr = hent->h_addr_list[i++])) {
327 mxip_addr mxip;
328 mxip.ip = *(guint32 *) (haddr);
329 mxip.pref = 0;
330 mxip.name = g_strdup(hent->h_name);
331 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));
332 }
333 }
334 return list;
335 }
336
337 #ifdef RESOLV_TEST
338 int
339 main(int argc, char *argv[])
340 {
341 GList *addr_list = NULL, *node;
342
343 g_print("starting res_init()\n");
344 g_print("retrans = %d, retry = %d\n", _res.retrans, _res.retry);
345 if (res_init() == 0) {
346 addr_list = resolve_dns_a(NULL, argv[1]);
347 g_print("A:\n");
348 foreach(addr_list, node) {
349 mxip_addr *p_mxip = (mxip_addr *) (node->data);
350 printf("name = %s\n IP = %s\n", p_mxip->name, inet_ntoa(*(struct in_addr *) &(p_mxip->ip)));
351 }
352 addr_list = resolve_dns_mx(NULL, argv[1]);
353 g_print("MX:\n");
354 foreach(addr_list, node) {
355 mxip_addr *p_mxip = (mxip_addr *) (node->data);
356 printf("name = %s\n IP = %s pref = %d\n", p_mxip->name,
357 inet_ntoa(*(struct in_addr *) &(p_mxip->ip)), p_mxip->pref);
358 }
359 {
360 guint32 ip;
361 dns_look_ip(argv[1], &ip);
362 printf("dns_look_ip: %s\n", inet_ntoa(*((struct in_addr *) (&ip))));
363 }
364 } else
365 printf("res_init() failed.\n");
366 }
367 #endif