4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
8 * This file is part of adns, which is
9 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
10 * Copyright (C) 1999-2000,2003,2006 Tony Finch
11 * Copyright (C) 1991 Massachusetts Institute of Technology
12 * (See the file INSTALL for full details.)
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
33 #include <sys/types.h>
36 #include <sys/socket.h>
37 #include <netinet/in.h>
38 #include <arpa/inet.h>
43 /* TCP connection management. */
45 static void tcp_close(adns_state ads) {
46 close(ads->tcpsocket);
48 ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
51 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
55 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
57 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
59 if (ads->tcpstate == server_connecting) {
60 /* Counts as a retry for all the queries waiting for TCP. */
61 for (qu= ads->tcpw.head; qu; qu= qu->next)
66 ads->tcpstate= server_broken;
67 ads->tcpserver= (serv+1)%ads->nservers;
70 static void tcp_connected(adns_state ads, struct timeval now) {
73 adns__debug(ads,ads->tcpserver,0,"TCP connected");
74 ads->tcpstate= server_ok;
75 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
77 assert(qu->state == query_tcpw);
78 adns__querysend_tcp(qu,now);
82 static void tcp_broken_events(adns_state ads) {
85 assert(ads->tcpstate == server_broken);
86 for (qu= ads->tcpw.head; qu; qu= nqu) {
88 assert(qu->state == query_tcpw);
89 if (qu->retries > ads->nservers) {
90 LIST_UNLINK(ads->tcpw,qu);
91 adns__query_fail(qu,adns_s_allservfail);
94 ads->tcpstate= server_disconnected;
97 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
100 struct protoent *proto;
102 for (tries=0; tries<ads->nservers; tries++) {
103 switch (ads->tcpstate) {
104 case server_connecting:
108 case server_disconnected:
114 assert(!ads->tcpsend.used);
115 assert(!ads->tcprecv.used);
116 assert(!ads->tcprecv_skip);
118 proto= getprotobyname("tcp");
120 adns__diag(ads,-1,0,"unable to find protocol no. for TCP !");
123 addr = &ads->servers[ads->tcpserver];
124 fd= socket(addr->addr.sa.sa_family, SOCK_STREAM, proto->p_proto);
126 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
129 r= adns__setnonblock(ads,fd);
131 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking:"
136 r= connect(fd,&addr->addr.sa,addr->len);
138 ads->tcpstate= server_connecting;
139 if (r==0) { tcp_connected(ads,now); return; }
140 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
141 ads->tcptimeout= now;
142 timevaladd(&ads->tcptimeout,TCPCONNMS);
145 adns__tcp_broken(ads,"connect",strerror(errno));
146 tcp_broken_events(ads);
150 /* Timeout handling functions. */
152 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
153 struct timeval *tv_buf) {
154 const struct timeval *now;
159 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
160 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
161 adns_globalsystemfailure(ads);
165 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
166 struct timeval *rbuf;
171 if (!rbuf) { *tv_io= rbuf= tvbuf; }
176 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
177 struct timeval maxto) {
178 struct timeval *rbuf;
183 *tvbuf= maxto; *tv_io= tvbuf;
185 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
187 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
188 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
191 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
192 struct timeval now, struct timeval maxtime) {
196 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
197 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
199 maxtime.tv_sec -= (now.tv_sec+2);
200 maxtime.tv_usec -= (now.tv_usec-2000000);
201 dr= ldiv(maxtime.tv_usec,1000000);
202 maxtime.tv_sec += dr.quot;
203 maxtime.tv_usec -= dr.quot*1000000;
204 if (maxtime.tv_sec<0) timerclear(&maxtime);
205 inter_maxto(tv_io,tvbuf,maxtime);
208 static void timeouts_queue(adns_state ads, int act,
209 struct timeval **tv_io, struct timeval *tvbuf,
210 struct timeval now, struct query_queue *queue) {
213 for (qu= queue->head; qu; qu= nqu) {
215 if (!timercmp(&now,&qu->timeout,>)) {
216 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
218 if (!act) { inter_immed(tv_io,tvbuf); return; }
219 LIST_UNLINK(*queue,qu);
220 if (qu->state != query_tosend) {
221 adns__query_fail(qu,adns_s_timeout);
223 adns__query_send(qu,now);
230 static void tcp_events(adns_state ads, int act,
231 struct timeval **tv_io, struct timeval *tvbuf,
232 struct timeval now) {
234 switch (ads->tcpstate) {
236 if (!act) { inter_immed(tv_io,tvbuf); return; }
237 tcp_broken_events(ads);
238 case server_disconnected: /* fall through */
239 if (!ads->tcpw.head) return;
240 if (!act) { inter_immed(tv_io,tvbuf); return; }
241 adns__tcp_tryconnect(ads,now);
244 if (ads->tcpw.head) return;
245 if (!ads->tcptimeout.tv_sec) {
246 assert(!ads->tcptimeout.tv_usec);
247 ads->tcptimeout= now;
248 timevaladd(&ads->tcptimeout,TCPIDLEMS);
250 case server_connecting: /* fall through */
251 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
252 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
255 /* TCP timeout has happened */
256 switch (ads->tcpstate) {
257 case server_connecting: /* failed to connect */
258 adns__tcp_broken(ads,"unable to make connection","timed out");
260 case server_ok: /* idle timeout */
262 ads->tcpstate= server_disconnected;
276 void adns__timeouts(adns_state ads, int act,
277 struct timeval **tv_io, struct timeval *tvbuf,
278 struct timeval now) {
279 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
280 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
281 tcp_events(ads,act,tv_io,tvbuf,now);
284 void adns_firsttimeout(adns_state ads,
285 struct timeval **tv_io, struct timeval *tvbuf,
286 struct timeval now) {
287 adns__consistency(ads,0,cc_entex);
288 adns__timeouts(ads, 0, tv_io,tvbuf, now);
289 adns__consistency(ads,0,cc_entex);
292 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
293 struct timeval tv_buf;
295 adns__consistency(ads,0,cc_entex);
296 adns__must_gettimeofday(ads,&now,&tv_buf);
297 if (now) adns__timeouts(ads, 1, 0,0, *now);
298 adns__consistency(ads,0,cc_entex);
301 /* fd handling functions. These are the top-level of the real work of
302 * reception and often transmission.
305 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
306 /* Returns the number of entries filled in. Always zeroes revents. */
308 assert(MAX_POLLFDS==2);
310 pollfds_buf[0].fd= ads->udpsocket;
311 pollfds_buf[0].events= POLLIN;
312 pollfds_buf[0].revents= 0;
314 switch (ads->tcpstate) {
315 case server_disconnected:
318 case server_connecting:
319 pollfds_buf[1].events= POLLOUT;
322 pollfds_buf[1].events=
323 ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
328 pollfds_buf[1].fd= ads->tcpsocket;
332 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
333 int want, dgramlen, r, udpaddrlen, serv, old_skip;
334 byte udpbuf[DNS_MAXUDP];
335 struct sockaddr_in udpaddr;
337 adns__consistency(ads,0,cc_entex);
339 switch (ads->tcpstate) {
340 case server_disconnected:
342 case server_connecting:
345 if (fd != ads->tcpsocket) break;
346 assert(!ads->tcprecv_skip);
348 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
349 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
350 ads->tcprecv.buf[ads->tcprecv_skip+1]);
351 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
352 old_skip= ads->tcprecv_skip;
353 ads->tcprecv_skip += 2+dgramlen;
354 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
355 dgramlen, ads->tcpserver, 1,*now);
363 ads->tcprecv.used -= ads->tcprecv_skip;
364 memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
366 ads->tcprecv_skip= 0;
367 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
368 assert(ads->tcprecv.used <= ads->tcprecv.avail);
369 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
370 r= read(ads->tcpsocket,
371 ads->tcprecv.buf+ads->tcprecv.used,
372 ads->tcprecv.avail-ads->tcprecv.used);
374 ads->tcprecv.used+= r;
377 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
378 if (errno==EINTR) continue;
379 if (errno_resources(errno)) { r= errno; goto xit; }
381 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
383 } while (ads->tcpstate == server_ok);
388 if (fd == ads->udpsocket) {
390 udpaddrlen= sizeof(udpaddr);
391 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
392 (struct sockaddr*)&udpaddr,&udpaddrlen);
394 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
395 if (errno == EINTR) continue;
396 if (errno_resources(errno)) { r= errno; goto xit; }
397 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
400 if (udpaddrlen != sizeof(udpaddr)) {
401 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
402 " (expected %lu)", udpaddrlen,
403 (unsigned long)sizeof(udpaddr));
406 if (udpaddr.sin_family != AF_INET) {
407 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
408 " %u (expected %u)",udpaddr.sin_family,AF_INET);
411 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
412 adns__diag(ads,-1,0,"datagram received from wrong port"
413 " %u (expected %u)", ntohs(udpaddr.sin_port),DNS_PORT);
417 serv < ads->nservers &&
418 !adns__sockaddr_equal_p(&ads->servers[serv].addr.sa,
419 (const struct sockaddr *)&udpaddr);
421 if (serv >= ads->nservers) {
422 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
423 inet_ntoa(udpaddr.sin_addr));
426 adns__procdgram(ads,udpbuf,r,serv,0,*now);
431 adns__consistency(ads,0,cc_entex);
435 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
438 adns__consistency(ads,0,cc_entex);
440 switch (ads->tcpstate) {
441 case server_disconnected:
444 case server_connecting:
445 if (fd != ads->tcpsocket) break;
446 assert(ads->tcprecv.used==0);
447 assert(ads->tcprecv_skip==0);
449 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
450 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
451 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
452 tcp_connected(ads,*now);
456 adns__tcp_broken(ads,"connect/read","sent data before first request");
459 if (errno==EINTR) continue;
460 if (errno_resources(errno)) { r= errno; goto xit; }
461 adns__tcp_broken(ads,"connect/read",strerror(errno));
465 if (fd != ads->tcpsocket) break;
466 while (ads->tcpsend.used) {
467 adns__sigpipe_protect(ads);
468 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
469 adns__sigpipe_unprotect(ads);
471 if (errno==EINTR) continue;
472 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
473 if (errno_resources(errno)) { r= errno; goto xit; }
474 adns__tcp_broken(ads,"write",strerror(errno));
477 ads->tcpsend.used -= r;
478 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
488 adns__consistency(ads,0,cc_entex);
492 int adns_processexceptional(adns_state ads, int fd,
493 const struct timeval *now) {
494 adns__consistency(ads,0,cc_entex);
495 switch (ads->tcpstate) {
496 case server_disconnected:
499 case server_connecting:
501 if (fd != ads->tcpsocket) break;
502 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
507 adns__consistency(ads,0,cc_entex);
511 static void fd_event(adns_state ads, int fd,
512 int revent, int pollflag,
513 int maxfd, const fd_set *fds,
514 int (*func)(adns_state, int fd,
515 const struct timeval *now),
516 struct timeval now, int *r_r) {
519 if (!(revent & pollflag)) return;
520 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
521 r= func(ads,fd,&now);
526 adns__diag(ads,-1,0,"process fd failed after select:"
527 " %s",strerror(errno));
528 adns_globalsystemfailure(ads);
533 void adns__fdevents(adns_state ads,
534 const struct pollfd *pollfds, int npollfds,
535 int maxfd, const fd_set *readfds,
536 const fd_set *writefds, const fd_set *exceptfds,
537 struct timeval now, int *r_r) {
540 for (i=0; i<npollfds; i++) {
542 if (fd >= maxfd) maxfd= fd+1;
543 revents= pollfds[i].revents;
544 #define EV(pollfl,fds,how) \
545 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
546 EV( POLLIN, readfds, readable );
547 EV( POLLOUT, writefds, writeable );
548 EV( POLLPRI, exceptfds, exceptional );
553 /* Wrappers for select(2). */
555 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
556 fd_set *writefds_io, fd_set *exceptfds_io,
557 struct timeval **tv_mod, struct timeval *tv_tobuf,
558 const struct timeval *now) {
559 struct timeval tv_nowbuf;
560 struct pollfd pollfds[MAX_POLLFDS];
561 int i, fd, maxfd, npollfds;
563 adns__consistency(ads,0,cc_entex);
565 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
566 /* The caller is planning to sleep. */
567 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
568 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
569 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
572 npollfds= adns__pollfds(ads,pollfds);
574 for (i=0; i<npollfds; i++) {
576 if (fd >= maxfd) maxfd= fd+1;
577 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
578 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
579 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
584 adns__consistency(ads,0,cc_entex);
587 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
588 const fd_set *writefds, const fd_set *exceptfds,
589 const struct timeval *now) {
590 struct timeval tv_buf;
591 struct pollfd pollfds[MAX_POLLFDS];
594 adns__consistency(ads,0,cc_entex);
595 adns__must_gettimeofday(ads,&now,&tv_buf);
597 adns_processtimeouts(ads,now);
599 npollfds= adns__pollfds(ads,pollfds);
600 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
603 maxfd,readfds,writefds,exceptfds,
606 adns__consistency(ads,0,cc_entex);
609 /* General helpful functions. */
611 void adns_globalsystemfailure(adns_state ads) {
612 adns__consistency(ads,0,cc_entex);
614 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
615 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
617 switch (ads->tcpstate) {
618 case server_connecting:
620 adns__tcp_broken(ads,0,0);
622 case server_disconnected:
628 adns__consistency(ads,0,cc_entex);
631 int adns_processany(adns_state ads) {
634 struct pollfd pollfds[MAX_POLLFDS];
637 adns__consistency(ads,0,cc_entex);
639 r= gettimeofday(&now,0);
640 if (!r) adns_processtimeouts(ads,&now);
642 /* We just use adns__fdevents to loop over the fd's trying them.
643 * This seems more sensible than calling select, since we're most
644 * likely just to want to do a read on one or two fds anyway.
646 npollfds= adns__pollfds(ads,pollfds);
647 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
653 adns__consistency(ads,0,cc_entex);
657 void adns__autosys(adns_state ads, struct timeval now) {
658 if (ads->iflags & adns_if_noautosys) return;
659 adns_processany(ads);
662 int adns__internal_check(adns_state ads,
663 adns_query *query_io,
664 adns_answer **answer,
670 if (ads->output.head) {
671 qu= ads->output.head;
672 } else if (ads->udpw.head || ads->tcpw.head) {
678 if (qu->id>=0) return EAGAIN;
680 LIST_UNLINK(ads->output,qu);
682 if (context_r) *context_r= qu->ctx.ext;
688 int adns_wait(adns_state ads,
689 adns_query *query_io,
690 adns_answer **answer_r,
693 fd_set readfds, writefds, exceptfds;
694 struct timeval tvbuf, *tvp;
696 adns__consistency(ads,*query_io,cc_entex);
698 r= adns__internal_check(ads,query_io,answer_r,context_r);
699 if (r != EAGAIN) break;
701 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
702 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
704 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
706 if (errno == EINTR) {
707 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
709 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
710 adns_globalsystemfailure(ads);
714 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
717 adns__consistency(ads,0,cc_entex);
721 int adns_check(adns_state ads,
722 adns_query *query_io,
723 adns_answer **answer_r,
728 adns__consistency(ads,*query_io,cc_entex);
729 r= gettimeofday(&now,0);
730 if (!r) adns__autosys(ads,now);
732 r= adns__internal_check(ads,query_io,answer_r,context_r);
733 adns__consistency(ads,0,cc_entex);