Commit | Line | Data |
---|---|---|
b423e985 | 1 | /* |
e9e1a1f3 | 2 | * Copyright (c) 1985, 1989 Regents of the University of California. |
6b2f9dd0 KB |
3 | * All rights reserved. |
4 | * | |
5 | * Redistribution and use in source and binary forms are permitted | |
f4f66d2c KB |
6 | * provided that the above copyright notice and this paragraph are |
7 | * duplicated in all such forms and that any documentation, | |
8 | * advertising materials, and other materials related to such | |
9 | * distribution and use acknowledge that the software was developed | |
10 | * by the University of California, Berkeley. The name of the | |
11 | * University may not be used to endorse or promote products derived | |
12 | * from this software without specific prior written permission. | |
13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
15 | * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
b423e985 RC |
16 | */ |
17 | ||
2ce81398 | 18 | #if defined(LIBC_SCCS) && !defined(lint) |
f7d00d5e | 19 | static char sccsid[] = "@(#)res_send.c 6.24 (Berkeley) %G%"; |
6b2f9dd0 | 20 | #endif /* LIBC_SCCS and not lint */ |
8ea4199d | 21 | |
616a94ba RC |
22 | /* |
23 | * Send query to name server and wait for reply. | |
24 | */ | |
25 | ||
04a773cb | 26 | #include <sys/param.h> |
616a94ba RC |
27 | #include <sys/time.h> |
28 | #include <sys/socket.h> | |
679f3274 | 29 | #include <sys/uio.h> |
616a94ba RC |
30 | #include <netinet/in.h> |
31 | #include <stdio.h> | |
32 | #include <errno.h> | |
27df2740 | 33 | #include <arpa/nameser.h> |
f94b2f50 | 34 | #include <resolv.h> |
616a94ba RC |
35 | |
36 | extern int errno; | |
37 | ||
3126f4c0 | 38 | static int s = -1; /* socket used for communications */ |
9bb3997d | 39 | static struct sockaddr no_addr; |
15537e14 KD |
40 | |
41 | ||
42 | #ifndef FD_SET | |
43 | #define NFDBITS 32 | |
44 | #define FD_SETSIZE 32 | |
45 | #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) | |
46 | #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS))) | |
47 | #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS))) | |
48 | #define FD_ZERO(p) bzero((char *)(p), sizeof(*(p))) | |
49 | #endif | |
3126f4c0 | 50 | |
31f0ead0 | 51 | res_send(buf, buflen, answer, anslen) |
616a94ba RC |
52 | char *buf; |
53 | int buflen; | |
54 | char *answer; | |
55 | int anslen; | |
56 | { | |
57 | register int n; | |
e9e1a1f3 | 58 | int try, v_circuit, resplen, ns; |
2344735f | 59 | int gotsomewhere = 0, connected = 0; |
17b5e053 | 60 | int connreset = 0; |
616a94ba RC |
61 | u_short id, len; |
62 | char *cp; | |
ac3ceb42 | 63 | fd_set dsmask; |
616a94ba RC |
64 | struct timeval timeout; |
65 | HEADER *hp = (HEADER *) buf; | |
66 | HEADER *anhp = (HEADER *) answer; | |
679f3274 | 67 | struct iovec iov[2]; |
1ea504e8 | 68 | int terrno = ETIMEDOUT; |
2344735f | 69 | char junk[512]; |
616a94ba | 70 | |
ae94a224 | 71 | #ifdef DEBUG |
616a94ba | 72 | if (_res.options & RES_DEBUG) { |
31f0ead0 | 73 | printf("res_send()\n"); |
616a94ba RC |
74 | p_query(buf); |
75 | } | |
0b8992ca | 76 | #endif DEBUG |
31f0ead0 | 77 | if (!(_res.options & RES_INIT)) |
ae94a224 JB |
78 | if (res_init() == -1) { |
79 | return(-1); | |
80 | } | |
616a94ba RC |
81 | v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ; |
82 | id = hp->id; | |
83 | /* | |
84 | * Send request, RETRY times, or until successful | |
85 | */ | |
e9e1a1f3 | 86 | for (try = 0; try < _res.retry; try++) { |
0b8992ca KD |
87 | for (ns = 0; ns < _res.nscount; ns++) { |
88 | #ifdef DEBUG | |
89 | if (_res.options & RES_DEBUG) | |
90 | printf("Querying server (# %d) address = %s\n", ns+1, | |
2344735f | 91 | inet_ntoa(_res.nsaddr_list[ns].sin_addr)); |
0b8992ca | 92 | #endif DEBUG |
e9e1a1f3 | 93 | usevc: |
616a94ba | 94 | if (v_circuit) { |
2344735f MK |
95 | int truncated = 0; |
96 | ||
616a94ba | 97 | /* |
e9e1a1f3 MK |
98 | * Use virtual circuit; |
99 | * at most one attempt per server. | |
616a94ba | 100 | */ |
e9e1a1f3 | 101 | try = _res.retry; |
a5d4a4c0 | 102 | if (s < 0) { |
616a94ba | 103 | s = socket(AF_INET, SOCK_STREAM, 0); |
92a82fe4 | 104 | if (s < 0) { |
1ea504e8 | 105 | terrno = errno; |
92a82fe4 MK |
106 | #ifdef DEBUG |
107 | if (_res.options & RES_DEBUG) | |
f7d00d5e | 108 | perror("socket (vc) failed"); |
92a82fe4 MK |
109 | #endif DEBUG |
110 | continue; | |
111 | } | |
747d796e | 112 | if (connect(s, &(_res.nsaddr_list[ns]), |
a5d4a4c0 | 113 | sizeof(struct sockaddr)) < 0) { |
1ea504e8 | 114 | terrno = errno; |
ae94a224 | 115 | #ifdef DEBUG |
a5d4a4c0 | 116 | if (_res.options & RES_DEBUG) |
747d796e | 117 | perror("connect failed"); |
0b8992ca | 118 | #endif DEBUG |
a5d4a4c0 JB |
119 | (void) close(s); |
120 | s = -1; | |
121 | continue; | |
122 | } | |
616a94ba RC |
123 | } |
124 | /* | |
125 | * Send length & message | |
126 | */ | |
3126f4c0 | 127 | len = htons((u_short)buflen); |
679f3274 JB |
128 | iov[0].iov_base = (caddr_t)&len; |
129 | iov[0].iov_len = sizeof(len); | |
130 | iov[1].iov_base = buf; | |
131 | iov[1].iov_len = buflen; | |
132 | if (writev(s, iov, 2) != sizeof(len) + buflen) { | |
1ea504e8 | 133 | terrno = errno; |
ae94a224 | 134 | #ifdef DEBUG |
616a94ba | 135 | if (_res.options & RES_DEBUG) |
747d796e | 136 | perror("write failed"); |
0b8992ca | 137 | #endif DEBUG |
616a94ba RC |
138 | (void) close(s); |
139 | s = -1; | |
140 | continue; | |
141 | } | |
142 | /* | |
143 | * Receive length & response | |
144 | */ | |
145 | cp = answer; | |
146 | len = sizeof(short); | |
679f3274 | 147 | while (len != 0 && |
747d796e | 148 | (n = read(s, (char *)cp, (int)len)) > 0) { |
616a94ba RC |
149 | cp += n; |
150 | len -= n; | |
151 | } | |
152 | if (n <= 0) { | |
1ea504e8 | 153 | terrno = errno; |
ae94a224 | 154 | #ifdef DEBUG |
616a94ba | 155 | if (_res.options & RES_DEBUG) |
747d796e | 156 | perror("read failed"); |
0b8992ca | 157 | #endif DEBUG |
616a94ba RC |
158 | (void) close(s); |
159 | s = -1; | |
17b5e053 JB |
160 | /* |
161 | * A long running process might get its TCP | |
162 | * connection reset if the remote server was | |
163 | * restarted. Requery the server instead of | |
164 | * trying a new one. When there is only one | |
165 | * server, this means that a query might work | |
166 | * instead of failing. We only allow one reset | |
167 | * per query to prevent looping. | |
168 | */ | |
169 | if (terrno == ECONNRESET && !connreset) { | |
170 | connreset = 1; | |
171 | ns--; | |
172 | } | |
616a94ba RC |
173 | continue; |
174 | } | |
175 | cp = answer; | |
2344735f MK |
176 | if ((resplen = ntohs(*(u_short *)cp)) > anslen) { |
177 | #ifdef DEBUG | |
178 | if (_res.options & RES_DEBUG) | |
179 | fprintf(stderr, "response truncated\n"); | |
180 | #endif DEBUG | |
181 | len = anslen; | |
182 | truncated = 1; | |
183 | } else | |
184 | len = resplen; | |
679f3274 | 185 | while (len != 0 && |
747d796e | 186 | (n = read(s, (char *)cp, (int)len)) > 0) { |
616a94ba RC |
187 | cp += n; |
188 | len -= n; | |
189 | } | |
190 | if (n <= 0) { | |
1ea504e8 | 191 | terrno = errno; |
ae94a224 | 192 | #ifdef DEBUG |
616a94ba | 193 | if (_res.options & RES_DEBUG) |
747d796e | 194 | perror("read failed"); |
0b8992ca | 195 | #endif DEBUG |
616a94ba RC |
196 | (void) close(s); |
197 | s = -1; | |
198 | continue; | |
199 | } | |
2344735f MK |
200 | if (truncated) { |
201 | /* | |
202 | * Flush rest of answer | |
203 | * so connection stays in synch. | |
204 | */ | |
205 | anhp->tc = 1; | |
206 | len = resplen - anslen; | |
207 | while (len != 0) { | |
208 | n = (len > sizeof(junk) ? | |
209 | sizeof(junk) : len); | |
210 | if ((n = read(s, junk, n)) > 0) | |
211 | len -= n; | |
212 | else | |
213 | break; | |
214 | } | |
215 | } | |
616a94ba RC |
216 | } else { |
217 | /* | |
218 | * Use datagrams. | |
219 | */ | |
f7d00d5e | 220 | if (s < 0) { |
616a94ba | 221 | s = socket(AF_INET, SOCK_DGRAM, 0); |
f7d00d5e JB |
222 | if (s < 0) { |
223 | terrno = errno; | |
224 | #ifdef DEBUG | |
225 | if (_res.options & RES_DEBUG) | |
226 | perror("socket (dg) failed"); | |
227 | #endif DEBUG | |
228 | continue; | |
229 | } | |
230 | } | |
92a82fe4 | 231 | #if BSD >= 43 |
e9e1a1f3 MK |
232 | /* |
233 | * I'm tired of answering this question, so: | |
234 | * On a 4.3BSD+ machine (client and server, | |
235 | * actually), sending to a nameserver datagram | |
236 | * port with no nameserver will cause an | |
237 | * ICMP port unreachable message to be returned. | |
238 | * If our datagram socket is "connected" to the | |
239 | * server, we get an ECONNREFUSED error on the next | |
240 | * socket operation, and select returns if the | |
241 | * error message is received. We can thus detect | |
242 | * the absence of a nameserver without timing out. | |
243 | * If we have sent queries to at least two servers, | |
244 | * however, we don't want to remain connected, | |
245 | * as we wish to receive answers from the first | |
246 | * server to respond. | |
247 | */ | |
248 | if (_res.nscount == 1 || (try == 0 && ns == 0)) { | |
7a8f7802 | 249 | /* |
9bb3997d MK |
250 | * Don't use connect if we might |
251 | * still receive a response | |
252 | * from another server. | |
7a8f7802 | 253 | */ |
2344735f MK |
254 | if (connected == 0) { |
255 | if (connect(s, &_res.nsaddr_list[ns], | |
256 | sizeof(struct sockaddr)) < 0) { | |
257 | #ifdef DEBUG | |
258 | if (_res.options & RES_DEBUG) | |
259 | perror("connect"); | |
260 | #endif DEBUG | |
261 | continue; | |
262 | } | |
263 | connected = 1; | |
264 | } | |
265 | if (send(s, buf, buflen, 0) != buflen) { | |
ae94a224 | 266 | #ifdef DEBUG |
7a8f7802 | 267 | if (_res.options & RES_DEBUG) |
2344735f | 268 | perror("send"); |
0b8992ca | 269 | #endif DEBUG |
7a8f7802 KD |
270 | continue; |
271 | } | |
fee59cfd MK |
272 | } else { |
273 | /* | |
274 | * Disconnect if we want to listen | |
275 | * for responses from more than one server. | |
276 | */ | |
277 | if (connected) { | |
278 | (void) connect(s, &no_addr, | |
279 | sizeof(no_addr)); | |
280 | connected = 0; | |
281 | } | |
7a8f7802 | 282 | #endif BSD |
fee59cfd MK |
283 | if (sendto(s, buf, buflen, 0, |
284 | &_res.nsaddr_list[ns], | |
285 | sizeof(struct sockaddr)) != buflen) { | |
92a82fe4 | 286 | #ifdef DEBUG |
fee59cfd MK |
287 | if (_res.options & RES_DEBUG) |
288 | perror("sendto"); | |
92a82fe4 | 289 | #endif DEBUG |
fee59cfd MK |
290 | continue; |
291 | } | |
292 | #if BSD >= 43 | |
616a94ba | 293 | } |
fee59cfd | 294 | #endif |
7a8f7802 | 295 | |
616a94ba | 296 | /* |
747d796e | 297 | * Wait for reply |
616a94ba | 298 | */ |
e9e1a1f3 MK |
299 | timeout.tv_sec = (_res.retrans << try); |
300 | if (try > 0) | |
301 | timeout.tv_sec /= _res.nscount; | |
747d796e KD |
302 | if (timeout.tv_sec <= 0) |
303 | timeout.tv_sec = 1; | |
616a94ba | 304 | timeout.tv_usec = 0; |
87b12937 | 305 | wait: |
ac3ceb42 KD |
306 | FD_ZERO(&dsmask); |
307 | FD_SET(s, &dsmask); | |
679f3274 JB |
308 | n = select(s+1, &dsmask, (fd_set *)NULL, |
309 | (fd_set *)NULL, &timeout); | |
616a94ba | 310 | if (n < 0) { |
ae94a224 | 311 | #ifdef DEBUG |
616a94ba | 312 | if (_res.options & RES_DEBUG) |
747d796e | 313 | perror("select"); |
0b8992ca | 314 | #endif DEBUG |
616a94ba RC |
315 | continue; |
316 | } | |
317 | if (n == 0) { | |
318 | /* | |
319 | * timeout | |
320 | */ | |
ae94a224 | 321 | #ifdef DEBUG |
616a94ba RC |
322 | if (_res.options & RES_DEBUG) |
323 | printf("timeout\n"); | |
0b8992ca | 324 | #endif DEBUG |
e9e1a1f3 | 325 | #if BSD >= 43 |
92a82fe4 | 326 | gotsomewhere = 1; |
e9e1a1f3 | 327 | #endif |
616a94ba RC |
328 | continue; |
329 | } | |
dd7a6a73 | 330 | if ((resplen = recv(s, answer, anslen, 0)) <= 0) { |
ae94a224 | 331 | #ifdef DEBUG |
616a94ba | 332 | if (_res.options & RES_DEBUG) |
747d796e | 333 | perror("recvfrom"); |
0b8992ca | 334 | #endif DEBUG |
616a94ba RC |
335 | continue; |
336 | } | |
92a82fe4 | 337 | gotsomewhere = 1; |
616a94ba RC |
338 | if (id != anhp->id) { |
339 | /* | |
340 | * response from old query, ignore it | |
341 | */ | |
ae94a224 | 342 | #ifdef DEBUG |
616a94ba | 343 | if (_res.options & RES_DEBUG) { |
616a94ba | 344 | printf("old answer:\n"); |
616a94ba RC |
345 | p_query(answer); |
346 | } | |
0b8992ca | 347 | #endif DEBUG |
87b12937 | 348 | goto wait; |
616a94ba RC |
349 | } |
350 | if (!(_res.options & RES_IGNTC) && anhp->tc) { | |
351 | /* | |
e9e1a1f3 MK |
352 | * get rest of answer; |
353 | * use TCP with same server. | |
616a94ba | 354 | */ |
ae94a224 | 355 | #ifdef DEBUG |
616a94ba RC |
356 | if (_res.options & RES_DEBUG) |
357 | printf("truncated answer\n"); | |
0b8992ca | 358 | #endif DEBUG |
616a94ba RC |
359 | (void) close(s); |
360 | s = -1; | |
616a94ba | 361 | v_circuit = 1; |
e9e1a1f3 | 362 | goto usevc; |
616a94ba RC |
363 | } |
364 | } | |
ae94a224 | 365 | #ifdef DEBUG |
616a94ba RC |
366 | if (_res.options & RES_DEBUG) { |
367 | printf("got answer:\n"); | |
368 | p_query(answer); | |
369 | } | |
0b8992ca | 370 | #endif DEBUG |
a5d4a4c0 | 371 | /* |
e9e1a1f3 MK |
372 | * If using virtual circuits, we assume that the first server |
373 | * is preferred * over the rest (i.e. it is on the local | |
374 | * machine) and only keep that one open. | |
375 | * If we have temporarily opened a virtual circuit, | |
376 | * or if we haven't been asked to keep a socket open, | |
377 | * close the socket. | |
a5d4a4c0 | 378 | */ |
e9e1a1f3 MK |
379 | if ((v_circuit && |
380 | ((_res.options & RES_USEVC) == 0 || ns != 0)) || | |
381 | (_res.options & RES_STAYOPEN) == 0) { | |
a5d4a4c0 JB |
382 | (void) close(s); |
383 | s = -1; | |
a5d4a4c0 | 384 | } |
fee59cfd | 385 | return (resplen); |
0b8992ca | 386 | } |
616a94ba | 387 | } |
1ea504e8 JB |
388 | if (s >= 0) { |
389 | (void) close(s); | |
390 | s = -1; | |
391 | } | |
392 | if (v_circuit == 0) | |
393 | if (gotsomewhere == 0) | |
e9e1a1f3 | 394 | errno = ECONNREFUSED; /* no nameservers found */ |
1ea504e8 | 395 | else |
e9e1a1f3 | 396 | errno = ETIMEDOUT; /* no answer obtained */ |
92a82fe4 | 397 | else |
1ea504e8 | 398 | errno = terrno; |
616a94ba RC |
399 | return (-1); |
400 | } | |
3126f4c0 JB |
401 | |
402 | /* | |
403 | * This routine is for closing the socket if a virtual circuit is used and | |
404 | * the program wants to close it. This provides support for endhostent() | |
405 | * which expects to close the socket. | |
406 | * | |
407 | * This routine is not expected to be user visible. | |
408 | */ | |
409 | _res_close() | |
410 | { | |
411 | if (s != -1) { | |
412 | (void) close(s); | |
413 | s = -1; | |
414 | } | |
415 | } |