Copyright dates fixed; various TODOs added.
[adns] / src / event.c
CommitLineData
e576be50 1/*
2 * event.c
3 * - event loop core
4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
6 */
7/*
a719a4be 8 * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson
e576be50 9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2, or (at your option)
13 * any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software Foundation,
22 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
23 */
656b2da9 24
4353a5c4 25#include <string.h>
26#include <errno.h>
27#include <stdlib.h>
28
29#include <netdb.h>
30#include <arpa/inet.h>
31
32#include "internal.h"
37e28fde 33
ddfda861 34/* TCP connection management */
656b2da9 35
8402e34c 36void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
37 int serv;
4353a5c4 38 adns_query qu, nqu;
8402e34c 39
40 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
ddfda861 41 serv= ads->tcpserver;
68442019 42 adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why);
37e28fde 43 close(ads->tcpsocket);
44 ads->tcpstate= server_disconnected;
45
4353a5c4 46 for (qu= ads->timew.head; qu; qu= nqu) {
8402e34c 47 nqu= qu->next;
ddfda861 48 if (qu->state == query_udp) continue;
49 assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
50 qu->state= query_tcpwait;
51 qu->tcpfailed |= (1<<serv);
52 if (qu->tcpfailed == (1<<ads->nservers)-1) {
4353a5c4 53 LIST_UNLINK(ads->timew,qu);
3955725c 54 adns__query_fail(qu,adns_s_allservfail);
ddfda861 55 }
8402e34c 56 }
57
4353a5c4 58 ads->tcprecv.used= ads->tcpsend.used= 0;
8402e34c 59 ads->tcpserver= (serv+1)%ads->nservers;
60}
61
ddfda861 62static void tcp_connected(adns_state ads, struct timeval now) {
4353a5c4 63 adns_query qu, nqu;
64
68442019 65 adns__debug(ads,ads->tcpserver,0,"TCP connected");
4353a5c4 66 ads->tcpstate= server_ok;
ddfda861 67 for (qu= ads->timew.head; qu; qu= nqu) {
68 nqu= qu->next;
69 if (qu->state == query_udp) continue;
70 assert (qu->state == query_tcpwait);
3955725c 71 adns__query_tcp(qu,now);
ddfda861 72 }
73}
74
75void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
8402e34c 76 int r, fd, tries;
4353a5c4 77 struct sockaddr_in addr;
78 struct protoent *proto;
8402e34c 79
80 for (tries=0; tries<ads->nservers; tries++) {
81 if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
82 assert(ads->tcpstate == server_disconnected);
4353a5c4 83 assert(!ads->tcpsend.used);
84 assert(!ads->tcprecv.used);
8402e34c 85
86 proto= getprotobyname("tcp");
68442019 87 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
8402e34c 88 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
4353a5c4 89 if (fd<0) {
68442019 90 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
4353a5c4 91 return;
92 }
93 r= adns__setnonblock(ads,fd);
94 if (r) {
68442019 95 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
4353a5c4 96 close(fd);
97 return;
98 }
8402e34c 99 memset(&addr,0,sizeof(addr));
100 addr.sin_family= AF_INET;
98a3f706 101 addr.sin_port= htons(DNS_PORT);
8402e34c 102 addr.sin_addr= ads->servers[ads->tcpserver].addr;
103 r= connect(fd,&addr,sizeof(addr));
104 ads->tcpsocket= fd;
105 ads->tcpstate= server_connecting;
4353a5c4 106 if (r==0) { tcp_connected(ads,now); continue; }
8402e34c 107 if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
ddfda861 108 adns__tcp_broken(ads,"connect",strerror(errno));
8402e34c 109 }
110}
111
4353a5c4 112/* `Interest' functions - find out which fd's we might be interested in,
113 * and when we want to be called back for a timeout.
114 */
115
116static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
117 struct timeval maxto) {
118 struct timeval *rbuf;
119
120 if (!tv_io) return;
121 rbuf= *tv_io;
94436798 122 if (!rbuf) {
123 *tvbuf= maxto; *tv_io= tvbuf;
124 } else {
125 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
126 }
ffbda80c 127/*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
128 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
4353a5c4 129}
130
131static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
132 struct timeval now, struct timeval maxtime) {
133 ldiv_t dr;
134
ffbda80c 135/*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
136 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
4353a5c4 137 if (!tv_io) return;
94436798 138 maxtime.tv_sec -= (now.tv_sec+2);
139 maxtime.tv_usec -= (now.tv_usec-2000000);
140 dr= ldiv(maxtime.tv_usec,1000000);
4353a5c4 141 maxtime.tv_sec += dr.quot;
94436798 142 maxtime.tv_usec -= dr.quot*1000000;
143 if (maxtime.tv_sec<0) timerclear(&maxtime);
4353a5c4 144 inter_maxto(tv_io,tvbuf,maxtime);
145}
146
147static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
148 if (!maxfd || !fds) return;
149 if (fd>=*maxfd) *maxfd= fd+1;
150 FD_SET(fd,fds);
151}
152
153static void checktimeouts(adns_state ads, struct timeval now,
154 struct timeval **tv_io, struct timeval *tvbuf) {
155 adns_query qu, nqu;
156
157 for (qu= ads->timew.head; qu; qu= nqu) {
158 nqu= qu->next;
159 if (timercmp(&now,&qu->timeout,>)) {
160 LIST_UNLINK(ads->timew,qu);
161 if (qu->state != query_udp) {
3955725c 162 adns__query_fail(qu,adns_s_timeout);
4353a5c4 163 } else {
3955725c 164 adns__query_udp(qu,now);
4353a5c4 165 }
166 } else {
167 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
168 }
169 }
170}
171
172void adns_interest(adns_state ads, int *maxfd,
173 fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
174 struct timeval **tv_io, struct timeval *tvbuf) {
175 struct timeval now;
176 struct timeval tvto_lr;
177 int r;
178
ffbda80c 179/*fprintf(stderr,"adns_interest\n");*/
94436798 180
ffbda80c 181 r= gettimeofday(&now,0);
4353a5c4 182 if (r) {
68442019 183 adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s",
184 strerror(errno));
4353a5c4 185 timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
186 inter_maxto(tv_io, tvbuf, tvto_lr);
187 } else {
188 checktimeouts(ads,now,tv_io,tvbuf);
189 }
190
191 inter_addfd(maxfd,readfds,ads->udpsocket);
192
193 switch (ads->tcpstate) {
194 case server_disconnected:
195 break;
196 case server_connecting:
197 inter_addfd(maxfd,writefds,ads->tcpsocket);
198 break;
199 case server_ok:
200 inter_addfd(maxfd,readfds,ads->tcpsocket);
201 inter_addfd(maxfd,exceptfds,ads->tcpsocket);
202 if (ads->tcpsend.used) inter_addfd(maxfd,writefds,ads->tcpsocket);
e062dcae 203 break;
4353a5c4 204 default:
205 abort();
206 }
207}
208
ddfda861 209/* Callback procedures - these do the real work of reception and timeout, etc. */
210
211static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
212 return maxfd<0 || !fds ? 1 :
213 fd<maxfd && FD_ISSET(fd,fds);
214}
215
216static int internal_callback(adns_state ads, int maxfd,
217 const fd_set *readfds, const fd_set *writefds,
4353a5c4 218 const fd_set *exceptfds,
219 struct timeval now) {
220 int skip, want, dgramlen, count, udpaddrlen, r, serv;
98a3f706 221 byte udpbuf[DNS_MAXUDP];
37e28fde 222 struct sockaddr_in udpaddr;
656b2da9 223
224 count= 0;
ddfda861 225
226 switch (ads->tcpstate) {
227 case server_disconnected:
228 break;
229 case server_connecting:
656b2da9 230 if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
231 count++;
232 assert(ads->tcprecv.used==0);
e062dcae 233 if (!adns__vbuf_ensure(&ads->tcprecv,1)) return -1;
656b2da9 234 if (ads->tcprecv.buf) {
235 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
236 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
4353a5c4 237 tcp_connected(ads,now);
656b2da9 238 } else if (r>0) {
4353a5c4 239 adns__tcp_broken(ads,"connect/read","sent data before first request");
656b2da9 240 } else if (errno!=EINTR) {
4353a5c4 241 adns__tcp_broken(ads,"connect/read",strerror(errno));
656b2da9 242 }
243 }
244 }
ddfda861 245 break;
246 case server_ok:
247 count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
248 callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
249 (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
250 if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
656b2da9 251 skip= 0;
252 for (;;) {
253 if (ads->tcprecv.used<skip+2) {
254 want= 2;
255 } else {
256 dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
257 if (ads->tcprecv.used<skip+2+dgramlen) {
258 want= 2+dgramlen;
259 } else {
98a3f706 260 adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now);
656b2da9 261 skip+= 2+dgramlen; continue;
262 }
263 }
37e28fde 264 ads->tcprecv.used -= skip;
656b2da9 265 memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
e062dcae 266 skip= 0;
267 if (!adns__vbuf_ensure(&ads->tcprecv,want)) return -1;
268 assert(ads->tcprecv.used <= ads->tcprecv.avail);
269 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
656b2da9 270 r= read(ads->tcpsocket,
271 ads->tcprecv.buf+ads->tcprecv.used,
272 ads->tcprecv.avail-ads->tcprecv.used);
273 if (r>0) {
274 ads->tcprecv.used+= r;
275 } else {
276 if (r<0) {
277 if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
278 if (errno==EINTR) continue;
279 }
4353a5c4 280 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
656b2da9 281 break;
282 }
283 }
284 } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
4353a5c4 285 adns__tcp_broken(ads,"select","exceptional condition detected");
656b2da9 286 } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
287 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
288 if (r<0) {
289 if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
4353a5c4 290 adns__tcp_broken(ads,"write",strerror(errno));
656b2da9 291 }
292 } else if (r>0) {
293 ads->tcpsend.used -= r;
294 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
295 }
296 }
e062dcae 297 break;
ddfda861 298 default:
299 abort();
656b2da9 300 }
301
37e28fde 302 if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
303 count++;
304 for (;;) {
305 udpaddrlen= sizeof(udpaddr);
306 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
307 if (r<0) {
308 if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
309 errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
68442019 310 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
37e28fde 311 break;
312 }
313 if (udpaddrlen != sizeof(udpaddr)) {
68442019 314 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
315 " (expected %d)", udpaddrlen,sizeof(udpaddr));
37e28fde 316 continue;
317 }
318 if (udpaddr.sin_family != AF_INET) {
68442019 319 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
4353a5c4 320 " %u (expected %u)",udpaddr.sin_family,AF_INET);
37e28fde 321 continue;
322 }
98a3f706 323 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
68442019 324 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
98a3f706 325 ntohs(udpaddr.sin_port),DNS_PORT);
37e28fde 326 continue;
327 }
328 for (serv= 0;
329 serv < ads->nservers &&
330 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
331 serv++);
332 if (serv >= ads->nservers) {
68442019 333 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
4353a5c4 334 inet_ntoa(udpaddr.sin_addr));
37e28fde 335 continue;
336 }
98a3f706 337 adns__procdgram(ads,udpbuf,r,serv,now);
656b2da9 338 }
37e28fde 339 }
4353a5c4 340 return count;
656b2da9 341}
656b2da9 342
ddfda861 343int adns_callback(adns_state ads, int maxfd,
344 const fd_set *readfds, const fd_set *writefds,
345 const fd_set *exceptfds) {
346 struct timeval now;
656b2da9 347 int r;
37e28fde 348
4353a5c4 349 r= gettimeofday(&now,0); if (r) return -1;
350 checktimeouts(ads,now,0,0);
351 return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now);
656b2da9 352}
353
ddfda861 354/* User-visible functions and their implementation. */
355
4353a5c4 356void adns__autosys(adns_state ads, struct timeval now) {
ddfda861 357 if (ads->iflags & adns_if_noautosys) return;
358 adns_callback(ads,-1,0,0,0);
359}
360
656b2da9 361static int internal_check(adns_state ads,
362 adns_query *query_io,
363 adns_answer **answer,
364 void **context_r) {
365 adns_query qu;
366
367 qu= *query_io;
368 if (!qu) {
369 if (!ads->output.head) return EWOULDBLOCK;
370 qu= ads->output.head;
371 } else {
372 if (qu->id>=0) return EWOULDBLOCK;
373 }
374 LIST_UNLINK(ads->output,qu);
8e5b0abb 375 *answer= qu->answer;
a6536d8b 376 if (context_r) *context_r= qu->ctx.ext;
656b2da9 377 free(qu);
378 return 0;
379}
380
381int adns_wait(adns_state ads,
382 adns_query *query_io,
383 adns_answer **answer_r,
384 void **context_r) {
385 int r, maxfd, rsel, rcb;
386 fd_set readfds, writefds, exceptfds;
387 struct timeval tvbuf, *tvp;
388
389 for (;;) {
390 r= internal_check(ads,query_io,answer_r,context_r);
94436798 391 if (r != EWOULDBLOCK) return r;
656b2da9 392 maxfd= 0; tvp= 0;
37e28fde 393 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
656b2da9 394 adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
395 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
88372443 396 if (rsel==-1) {
397 if (errno == EINTR && !(ads->iflags & adns_if_eintr)) continue;
398 return errno;
399 }
4353a5c4 400 rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
656b2da9 401 assert(rcb==rsel);
402 }
403}
404
405int adns_check(adns_state ads,
406 adns_query *query_io,
407 adns_answer **answer_r,
408 void **context_r) {
4353a5c4 409 struct timeval now;
410 int r;
411
412 r= gettimeofday(&now,0); if (r) return errno;
413 adns__autosys(ads,now);
656b2da9 414 return internal_check(ads,query_io,answer_r,context_r);
415}