masqmail-0.2: 8c55886cacd8 src/lookup.c

masqmail-0.2

view src/lookup.c @ 3:8c55886cacd8

man pages will be maintained in troff now

author	meillo@marmaro.de
date	Fri, 26 Sep 2008 21:40:10 +0200
parents
children	26e34ae9a3e3

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 */

18 #include <sys/types.h>

19 #include <netinet/in.h>

20 #include <arpa/nameser.h>

21 #include <resolv.h>

23 #include "masqmail.h"

25 #ifdef RESOLV_TEST

27 #undef DEBUG

28 #define DEBUG(x) if(x > 0)

30 #define debugf g_print

31 #endif

33 #ifdef ENABLE_RESOLVER

35 static union {

36 HEADER hdr;

37 unsigned char buf[PACKETSZ];

38 } response;

39 static unsigned char *resp_end;

40 static unsigned char *resp_pos;

42 static int num_answers;

43 static char name[MAX_DNSNAME];

45 unsigned short rr_type;

46 unsigned short rr_dlen;

48 static

49 unsigned short getshort(unsigned char *c)

50 {

51 unsigned short u;

52 u = c[0];

53 return (u << 8) + c[1];

54 }

56 static

57 int dns_resolve(char *domain, int type, gboolean do_search)

58 {

59 int n;

60 int i;

62 int resp_len;

63 /*errno = 0;*/

65 /*

66 if (!stralloc_copy(&glue,domain)) return DNS_MEM;

67 if (!stralloc_0(&glue)) return DNS_MEM;

68 */

70 // resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));

71 DEBUG(5) debugf("DNS: before res_search()\n");

72 if(do_search)

73 resp_len = res_search(domain, C_IN, type, response.buf, sizeof(response));

74 else

75 resp_len = res_query(domain, C_IN, type, response.buf, sizeof(response));

76 DEBUG(5) debugf("DBG: after res_search()\n");

78 if (resp_len <= 0){

79 /*

80 if (errno == ECONNREFUSED) return DNS_SOFT;

81 if (h_errno == TRY_AGAIN) return DNS_SOFT;

82 return DNS_HARD;

83 */

84 return -1;

85 }

86 if (resp_len >= sizeof(response))

87 resp_len = sizeof(response);

89 resp_end = response.buf + resp_len;

90 resp_pos = response.buf + sizeof(HEADER);

91 n = ntohs(response.hdr.qdcount);

93 while (n-- > 0){

94 i = dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME);

95 if (i < 0)

96 return -1;

97 DEBUG(5) debugf("DBG: resolve name = %s\n", name);

98 resp_pos += i;

99 i = resp_end - resp_pos;

100 if (i < QFIXEDSZ)

101 return -1;

102 resp_pos += QFIXEDSZ;

103 }

104 num_answers = ntohs(response.hdr.ancount);

105

106 return 0;

107 }

108

109 static int dns_next()

110 {

111 int i;

112

113 if (num_answers <= 0) 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

136 int dns_getip(guint32 *ip)

137 {

138 int ret;

139

140 if((ret = dns_next())) return ret;

141

142 if (rr_type == T_A){

143 if (rr_dlen < 4)

144 return -1; /* soft */

145 *ip = *(guint32 *)(resp_pos);

146 DEBUG(5) debugf("DNS: dns_getip(): ip = %s\n", inet_ntoa(*(struct in_addr*)ip));

147 resp_pos += rr_dlen;

148

149 return 1;

150 }

151 resp_pos += rr_dlen;

152 return 0;

153 }

154

155 static

156 int dns_getmx(int *pref)

157 {

158 int ret;

159

160 if((ret = dns_next())) return ret;

161

162 if (rr_type == T_MX){

163 if (rr_dlen < 3)

164 return -1; /* soft */

165

166 *pref = (resp_pos[0] << 8) + resp_pos[1];

167 if (dn_expand(response.buf, resp_end, resp_pos + 2, name, MAX_DNSNAME) < 0)

168 return -1;

169

170 resp_pos += rr_dlen;

171

172 return 1;

173 }

174 resp_pos += rr_dlen;

175 return 0;

176 }

177

178 /*

179 static

180 int dns_getname(int type)

181 {

182 int ret;

183

184 if((ret = dns_next())) return ret;

185

186 if (rr_type == type){

187 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)

188 return -1;

189

190 resp_pos += rr_dlen;

191

192 return 1;

193 }

194 resp_pos += rr_dlen;

195 return 0;

196 }

197 */

198

199 static

200 int dns_look_ip(gchar *domain, guint32 *ip)

201 {

202 gchar *n = domain;

203

204 while(TRUE){

205 if(dns_resolve(n, T_A, FALSE) == 0){

206 dns_next();

207 if(rr_type == T_A){

208 if (rr_dlen < 4)

209 return -1; /* soft */

210 *ip = *(guint32 *)(resp_pos);

211

212 DEBUG(5) debugf("DNS: dns_look_ip(): ip = %s\n",

213 inet_ntoa(*(struct in_addr*)ip));

214

215 resp_pos += rr_dlen;

216 return 0;

217 }else if(rr_type == T_CNAME){

218 if (dn_expand(response.buf, resp_end, resp_pos, name, MAX_DNSNAME) < 0)

219 return -1;

220

221 DEBUG(5) debugf("DNS: (CNAME) dns_look_ip(): name = %s\n", name);

222

223 resp_pos += rr_dlen;

224 n = name;

225 }else

226 return -1;

227 }else

228 return -1;

229 }

230 }

231

232 GList *resolve_dns_a(GList *list, gchar *domain)

233 {

234 int ret;

235

236 DEBUG(5) debugf("DNS: resolve_dns_a entered\n");

237

238 if(dns_resolve(domain, T_A, TRUE) == 0){

239 mxip_addr mxip;

240 while((ret = dns_getip(&(mxip.ip))) != 2){

241 if(ret == 1){

242 mxip.name = g_strdup(name);

243 mxip.pref = 0;

244 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));

245 }

246 }

247 }

248 return list;

249 }

250

251 static

252 gint _mx_sort_func(gconstpointer aa, gconstpointer bb)

253 {

254 const mxip_addr *a = (mxip_addr *)aa;

255 const mxip_addr *b = (mxip_addr *)bb;

256

257 if(a->pref == b->pref)

258 return a->ip - b->ip;

259 else

260 return a->pref - b->pref;

261 }

262

263 GList *resolve_dns_mx(GList *list, gchar *domain)

264 {

265 GList *node;

266 int ret;

267 int cnt = 0;

268

269 DEBUG(5) debugf("DNS: resolve_dns_mx entered\n");

270

271 if(dns_resolve(domain, T_MX, TRUE) == 0){

272 GList *node_next;

273 mxip_addr mxip;

274 while((ret = dns_getmx(&(mxip.pref))) != 2){

275 if(ret == 1){

276 mxip.name = g_strdup(name);

277 mxip.ip = rand();

278 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));

279 cnt++;

280 }

281 }

282

283 DEBUG(5) debugf("DNS: found %d mx records\n", cnt);

284

285 /* to randomize sequences with equal pref values,

286 we temporarily 'misused' the ip field and

287 put a random number in it as a secondary sort key.

288 */

289 list = g_list_sort(list, _mx_sort_func);

290

291 /* CNAME resolving has to be added as well. */

292

293 for(node = g_list_first(list);

294 node != NULL;

295 node = node_next){

296

297 mxip_addr *p_mxip = (mxip_addr *)(node->data);

298 node_next = g_list_next(node);

299

300 if(dns_look_ip(p_mxip->name, &(p_mxip->ip)) != 0){

301 DEBUG(1) debugf("DNS: could not resolve target of mx %s\n", p_mxip->name);

302 list = g_list_remove_link(list, node);

303 g_free(node->data);

304 g_list_free_1(node);

305 }

306 }

307 }

308 return list;

309 }

310

311 #endif

312

313 /* now something completely different... */

314

315 GList *resolve_byname(GList *list, gchar *domain)

316 {

317 struct hostent *hent;

318

319 DEBUG(5) debugf("DNS: resolve_byname entered\n");

320

321 if((hent = gethostbyname(domain))){

322 char *haddr;

323 int i = 0;

324 while((haddr = hent->h_addr_list[i++])){

325 mxip_addr mxip;

326 mxip.ip = *(guint32 *)(haddr);

327 mxip.pref = 0;

328 mxip.name = g_strdup(hent->h_name);

329 list = g_list_append(list, g_memdup(&mxip, sizeof(mxip)));

330 }

331 }

332 return list;

333 }

334

335 #ifdef RESOLV_TEST

336 int main(int argc, char *argv[])

337 {

338 GList *addr_list = NULL, *node;

339

340 g_print("starting res_init()\n");

341

342 g_print("retrans = %d, retry = %d\n", _res.retrans, _res.retry);

343

344 if(res_init() == 0){

345

346 addr_list = resolve_dns_a(NULL, argv[1]);

347 g_print("A:\n");

348

349 foreach(addr_list, node){

350 mxip_addr *p_mxip = (mxip_addr *)(node->data);

351

352 printf("name = %s\n IP = %s\n",

353 p_mxip->name,

354 inet_ntoa(*(struct in_addr *)&(p_mxip->ip)));

355 }

356 addr_list = resolve_dns_mx(NULL, argv[1]);

357 g_print("MX:\n");

358

359 foreach(addr_list, node){

360 mxip_addr *p_mxip = (mxip_addr *)(node->data);

361

362 printf("name = %s\n IP = %s pref = %d\n",

363 p_mxip->name,

364 inet_ntoa(*(struct in_addr *)&(p_mxip->ip)),

365 p_mxip->pref);

366 }

367 {

368 guint32 ip;

369 dns_look_ip(argv[1], &ip);

370 printf("dns_look_ip: %s\n", inet_ntoa(*((struct in_addr *)(&ip))));

371 }

372 }else

373 printf("res_init() failed.\n");

374

375 }

376 #endif