4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
9 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
11 * It is part of adns, which is
12 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
13 * Copyright (C) 1999 Tony Finch <dot@dotat.at>
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software Foundation,
27 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
34 #include <sys/types.h>
37 #include <sys/socket.h>
38 #include <netinet/in.h>
39 #include <arpa/inet.h>
44 /* TCP connection management. */
46 static void tcp_close(adns_state ads) {
50 close(ads->tcpsocket);
52 ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
55 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
59 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
61 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
63 if (ads->tcpstate == server_connecting) {
64 /* Counts as a retry for all the queries waiting for TCP. */
65 for (qu= ads->tcpw.head; qu; qu= qu->next)
70 ads->tcpstate= server_broken;
71 ads->tcpserver= (serv+1)%ads->nservers;
74 static void tcp_connected(adns_state ads, struct timeval now) {
77 adns__debug(ads,ads->tcpserver,0,"TCP connected");
78 ads->tcpstate= server_ok;
79 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
81 assert(qu->state == query_tcpw);
82 adns__querysend_tcp(qu,now);
86 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
88 struct sockaddr_in addr;
89 struct protoent *proto;
91 for (tries=0; tries<ads->nservers; tries++) {
92 switch (ads->tcpstate) {
93 case server_connecting:
97 case server_disconnected:
103 assert(!ads->tcpsend.used);
104 assert(!ads->tcprecv.used);
105 assert(!ads->tcprecv_skip);
107 proto= getprotobyname("tcp");
108 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
109 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
111 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
114 r= adns__setnonblock(ads,fd);
116 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
120 memset(&addr,0,sizeof(addr));
121 addr.sin_family= AF_INET;
122 addr.sin_port= htons(DNS_PORT);
123 addr.sin_addr= ads->servers[ads->tcpserver].addr;
124 r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
126 ads->tcpstate= server_connecting;
127 if (r==0) { tcp_connected(ads,now); return; }
128 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
129 ads->tcptimeout= now;
130 timevaladd(&ads->tcptimeout,TCPCONNMS);
133 adns__tcp_broken(ads,"connect",strerror(errno));
134 ads->tcpstate= server_disconnected;
138 /* Timeout handling functions. */
140 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
141 struct timeval *tv_buf) {
142 const struct timeval *now;
147 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
148 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
149 adns_globalsystemfailure(ads);
153 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
154 struct timeval *rbuf;
159 if (!rbuf) { *tv_io= rbuf= tvbuf; }
164 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
165 struct timeval maxto) {
166 struct timeval *rbuf;
171 *tvbuf= maxto; *tv_io= tvbuf;
173 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
175 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
176 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
179 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
180 struct timeval now, struct timeval maxtime) {
184 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
185 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
187 maxtime.tv_sec -= (now.tv_sec+2);
188 maxtime.tv_usec -= (now.tv_usec-2000000);
189 dr= ldiv(maxtime.tv_usec,1000000);
190 maxtime.tv_sec += dr.quot;
191 maxtime.tv_usec -= dr.quot*1000000;
192 if (maxtime.tv_sec<0) timerclear(&maxtime);
193 inter_maxto(tv_io,tvbuf,maxtime);
196 static void timeouts_queue(adns_state ads, int act,
197 struct timeval **tv_io, struct timeval *tvbuf,
198 struct timeval now, struct query_queue *queue) {
201 for (qu= queue->head; qu; qu= nqu) {
203 if (!timercmp(&now,&qu->timeout,>)) {
204 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
206 if (!act) { inter_immed(tv_io,tvbuf); return; }
207 LIST_UNLINK(*queue,qu);
208 if (qu->state != query_tosend) {
209 adns__query_fail(qu,adns_s_timeout);
211 adns__query_send(qu,now);
218 static void tcp_events(adns_state ads, int act,
219 struct timeval **tv_io, struct timeval *tvbuf,
220 struct timeval now) {
224 switch (ads->tcpstate) {
226 if (!act) { inter_immed(tv_io,tvbuf); return; }
227 for (qu= ads->tcpw.head; qu; qu= nqu) {
229 assert(qu->state == query_tcpw);
230 if (qu->retries > ads->nservers) {
231 LIST_UNLINK(ads->tcpw,qu);
232 adns__query_fail(qu,adns_s_allservfail);
235 ads->tcpstate= server_disconnected;
236 case server_disconnected: /* fall through */
237 if (!ads->tcpw.head) return;
238 if (!act) { inter_immed(tv_io,tvbuf); return; }
239 adns__tcp_tryconnect(ads,now);
242 if (ads->tcpw.head) return;
243 if (!ads->tcptimeout.tv_sec) {
244 assert(!ads->tcptimeout.tv_usec);
245 ads->tcptimeout= now;
246 timevaladd(&ads->tcptimeout,TCPIDLEMS);
248 case server_connecting: /* fall through */
249 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
250 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
253 /* TCP timeout has happened */
254 switch (ads->tcpstate) {
255 case server_connecting: /* failed to connect */
256 adns__tcp_broken(ads,"unable to make connection","timed out");
258 case server_ok: /* idle timeout */
260 ads->tcpstate= server_disconnected;
274 void adns__timeouts(adns_state ads, int act,
275 struct timeval **tv_io, struct timeval *tvbuf,
276 struct timeval now) {
277 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
278 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
279 tcp_events(ads,act,tv_io,tvbuf,now);
282 void adns_firsttimeout(adns_state ads,
283 struct timeval **tv_io, struct timeval *tvbuf,
284 struct timeval now) {
285 adns__consistency(ads,0,cc_entex);
286 adns__timeouts(ads, 0, tv_io,tvbuf, now);
287 adns__consistency(ads,0,cc_entex);
290 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
291 struct timeval tv_buf;
293 adns__consistency(ads,0,cc_entex);
294 adns__must_gettimeofday(ads,&now,&tv_buf);
295 if (now) adns__timeouts(ads, 1, 0,0, *now);
296 adns__consistency(ads,0,cc_entex);
299 /* fd handling functions. These are the top-level of the real work of
300 * reception and often transmission.
303 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
304 /* Returns the number of entries filled in. Always zeroes revents. */
306 assert(MAX_POLLFDS==2);
308 pollfds_buf[0].fd= ads->udpsocket;
309 pollfds_buf[0].events= POLLIN;
310 pollfds_buf[0].revents= 0;
312 switch (ads->tcpstate) {
313 case server_disconnected:
316 case server_connecting:
317 pollfds_buf[1].events= POLLOUT;
320 pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
325 pollfds_buf[1].fd= ads->tcpsocket;
329 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
330 int want, dgramlen, r, udpaddrlen, serv, old_skip;
331 byte udpbuf[DNS_MAXUDP];
332 struct sockaddr_in udpaddr;
334 adns__consistency(ads,0,cc_entex);
336 switch (ads->tcpstate) {
337 case server_disconnected:
339 case server_connecting:
342 if (fd != ads->tcpsocket) break;
343 assert(!ads->tcprecv_skip);
345 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
346 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
347 ads->tcprecv.buf[ads->tcprecv_skip+1]);
348 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
349 old_skip= ads->tcprecv_skip;
350 ads->tcprecv_skip += 2+dgramlen;
351 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
352 dgramlen, ads->tcpserver, 1,*now);
360 ads->tcprecv.used -= ads->tcprecv_skip;
361 memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
362 ads->tcprecv_skip= 0;
363 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
364 assert(ads->tcprecv.used <= ads->tcprecv.avail);
365 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
366 r= read(ads->tcpsocket,
367 ads->tcprecv.buf+ads->tcprecv.used,
368 ads->tcprecv.avail-ads->tcprecv.used);
370 ads->tcprecv.used+= r;
373 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
374 if (errno==EINTR) continue;
375 if (errno_resources(errno)) { r= errno; goto xit; }
377 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
379 } while (ads->tcpstate == server_ok);
384 if (fd == ads->udpsocket) {
386 udpaddrlen= sizeof(udpaddr);
387 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
388 (struct sockaddr*)&udpaddr,&udpaddrlen);
390 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
391 if (errno == EINTR) continue;
392 if (errno_resources(errno)) { r= errno; goto xit; }
393 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
396 if (udpaddrlen != sizeof(udpaddr)) {
397 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
398 " (expected %d)", udpaddrlen,sizeof(udpaddr));
401 if (udpaddr.sin_family != AF_INET) {
402 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
403 " %u (expected %u)",udpaddr.sin_family,AF_INET);
406 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
407 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
408 ntohs(udpaddr.sin_port),DNS_PORT);
412 serv < ads->nservers &&
413 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
415 if (serv >= ads->nservers) {
416 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
417 inet_ntoa(udpaddr.sin_addr));
420 adns__procdgram(ads,udpbuf,r,serv,0,*now);
425 adns__consistency(ads,0,cc_entex);
429 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
432 adns__consistency(ads,0,cc_entex);
434 switch (ads->tcpstate) {
435 case server_disconnected:
438 case server_connecting:
439 if (fd != ads->tcpsocket) break;
440 assert(ads->tcprecv.used==0);
441 assert(ads->tcprecv_skip==0);
443 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
444 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
445 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
446 tcp_connected(ads,*now);
450 adns__tcp_broken(ads,"connect/read","sent data before first request");
453 if (errno==EINTR) continue;
454 if (errno_resources(errno)) { r= errno; goto xit; }
455 adns__tcp_broken(ads,"connect/read",strerror(errno));
459 if (fd != ads->tcpsocket) break;
460 while (ads->tcpsend.used) {
461 adns__sigpipe_protect(ads);
462 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
463 adns__sigpipe_unprotect(ads);
465 if (errno==EINTR) continue;
466 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
467 if (errno_resources(errno)) { r= errno; goto xit; }
468 adns__tcp_broken(ads,"write",strerror(errno));
471 ads->tcpsend.used -= r;
472 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
482 adns__consistency(ads,0,cc_entex);
486 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
487 adns__consistency(ads,0,cc_entex);
488 switch (ads->tcpstate) {
489 case server_disconnected:
492 case server_connecting:
494 if (fd != ads->tcpsocket) break;
495 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
500 adns__consistency(ads,0,cc_entex);
504 static void fd_event(adns_state ads, int fd,
505 int revent, int pollflag,
506 int maxfd, const fd_set *fds,
507 int (*func)(adns_state, int fd, const struct timeval *now),
508 struct timeval now, int *r_r) {
511 if (!(revent & pollflag)) return;
512 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
513 r= func(ads,fd,&now);
518 adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
519 adns_globalsystemfailure(ads);
524 void adns__fdevents(adns_state ads,
525 const struct pollfd *pollfds, int npollfds,
526 int maxfd, const fd_set *readfds,
527 const fd_set *writefds, const fd_set *exceptfds,
528 struct timeval now, int *r_r) {
531 for (i=0; i<npollfds; i++) {
533 if (fd >= maxfd) maxfd= fd+1;
534 revents= pollfds[i].revents;
535 fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
536 fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
537 fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
541 /* Wrappers for select(2). */
543 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
544 fd_set *writefds_io, fd_set *exceptfds_io,
545 struct timeval **tv_mod, struct timeval *tv_tobuf,
546 const struct timeval *now) {
547 struct timeval tv_nowbuf;
548 struct pollfd pollfds[MAX_POLLFDS];
549 int i, fd, maxfd, npollfds;
551 adns__consistency(ads,0,cc_entex);
553 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
554 /* The caller is planning to sleep. */
555 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
556 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
557 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
560 npollfds= adns__pollfds(ads,pollfds);
562 for (i=0; i<npollfds; i++) {
564 if (fd >= maxfd) maxfd= fd+1;
565 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
566 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
567 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
572 adns__consistency(ads,0,cc_entex);
575 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
576 const fd_set *writefds, const fd_set *exceptfds,
577 const struct timeval *now) {
578 struct timeval tv_buf;
579 struct pollfd pollfds[MAX_POLLFDS];
582 adns__consistency(ads,0,cc_entex);
583 adns__must_gettimeofday(ads,&now,&tv_buf);
585 adns_processtimeouts(ads,now);
587 npollfds= adns__pollfds(ads,pollfds);
588 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
591 maxfd,readfds,writefds,exceptfds,
594 adns__consistency(ads,0,cc_entex);
597 /* General helpful functions. */
599 void adns_globalsystemfailure(adns_state ads) {
600 adns__consistency(ads,0,cc_entex);
602 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
603 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
605 switch (ads->tcpstate) {
606 case server_connecting:
608 adns__tcp_broken(ads,0,0);
610 case server_disconnected:
616 adns__consistency(ads,0,cc_entex);
619 int adns_processany(adns_state ads) {
622 struct pollfd pollfds[MAX_POLLFDS];
625 adns__consistency(ads,0,cc_entex);
627 r= gettimeofday(&now,0);
628 if (!r) adns_processtimeouts(ads,&now);
630 /* We just use adns__fdevents to loop over the fd's trying them.
631 * This seems more sensible than calling select, since we're most
632 * likely just to want to do a read on one or two fds anyway.
634 npollfds= adns__pollfds(ads,pollfds);
635 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
641 adns__consistency(ads,0,cc_entex);
645 void adns__autosys(adns_state ads, struct timeval now) {
646 if (ads->iflags & adns_if_noautosys) return;
647 adns_processany(ads);
650 int adns__internal_check(adns_state ads,
651 adns_query *query_io,
652 adns_answer **answer,
658 if (ads->output.head) {
659 qu= ads->output.head;
660 } else if (ads->udpw.head || ads->tcpw.head) {
666 if (qu->id>=0) return EAGAIN;
668 LIST_UNLINK(ads->output,qu);
670 if (context_r) *context_r= qu->ctx.ext;
676 int adns_wait(adns_state ads,
677 adns_query *query_io,
678 adns_answer **answer_r,
681 fd_set readfds, writefds, exceptfds;
682 struct timeval tvbuf, *tvp;
684 adns__consistency(ads,*query_io,cc_entex);
686 r= adns__internal_check(ads,query_io,answer_r,context_r);
687 if (r != EAGAIN) break;
689 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
690 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
692 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
694 if (errno == EINTR) {
695 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
697 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
698 adns_globalsystemfailure(ads);
702 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
705 adns__consistency(ads,0,cc_entex);
709 int adns_check(adns_state ads,
710 adns_query *query_io,
711 adns_answer **answer_r,
716 adns__consistency(ads,*query_io,cc_entex);
717 r= gettimeofday(&now,0);
718 if (!r) adns__autosys(ads,now);
720 r= adns__internal_check(ads,query_io,answer_r,context_r);
721 adns__consistency(ads,0,cc_entex);