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 #define ADD_POLLFD(wantfd, wantevents) do{ \
309 pollfds_buf[nwanted].fd= (wantfd); \
310 pollfds_buf[nwanted].events= (wantevents); \
311 pollfds_buf[nwanted].revents= 0; \
317 assert(MAX_POLLFDS == MAXUDP + 1);
319 for (i=0; i<ads->nudp; i++)
320 ADD_POLLFD(ads->udpsocket[i].fd, POLLIN);
322 switch (ads->tcpstate) {
323 case server_disconnected:
326 case server_connecting:
327 ADD_POLLFD(ads->tcpsocket, POLLOUT);
330 ADD_POLLFD(ads->tcpsocket,
331 ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI);
336 assert(nwanted<=MAX_POLLFDS);
341 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
342 int want, dgramlen, r, i, udpaddrlen, serv, old_skip;
343 byte udpbuf[DNS_MAXUDP];
344 char addrbuf[ADNS_ADDR2TEXT_BUFLEN];
345 struct udpsocket *udp;
346 adns_sockaddr udpaddr;
348 adns__consistency(ads,0,cc_entex);
350 switch (ads->tcpstate) {
351 case server_disconnected:
353 case server_connecting:
356 if (fd != ads->tcpsocket) break;
357 assert(!ads->tcprecv_skip);
359 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
360 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
361 ads->tcprecv.buf[ads->tcprecv_skip+1]);
362 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
363 old_skip= ads->tcprecv_skip;
364 ads->tcprecv_skip += 2+dgramlen;
365 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
366 dgramlen, ads->tcpserver, 1,*now);
374 ads->tcprecv.used -= ads->tcprecv_skip;
375 memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
377 ads->tcprecv_skip= 0;
378 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
379 assert(ads->tcprecv.used <= ads->tcprecv.avail);
380 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
381 r= read(ads->tcpsocket,
382 ads->tcprecv.buf+ads->tcprecv.used,
383 ads->tcprecv.avail-ads->tcprecv.used);
385 ads->tcprecv.used+= r;
388 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
389 if (errno==EINTR) continue;
390 if (errno_resources(errno)) { r= errno; goto xit; }
392 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
394 } while (ads->tcpstate == server_ok);
399 for (i=0; i<ads->nudp; i++) {
400 udp= &ads->udpsocket[i];
403 udpaddrlen= sizeof(udpaddr);
404 r= recvfrom(fd,udpbuf,sizeof(udpbuf),0, &udpaddr.sa,&udpaddrlen);
406 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
407 if (errno == EINTR) continue;
408 if (errno_resources(errno)) { r= errno; goto xit; }
409 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
413 serv < ads->nservers &&
414 !adns__sockaddr_equal_p(&udpaddr.sa,
415 &ads->servers[serv].addr.sa);
417 if (serv >= ads->nservers) {
418 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
419 adns__sockaddr_ntoa(&udpaddr.sa, addrbuf));
422 adns__procdgram(ads,udpbuf,r,serv,0,*now);
429 adns__consistency(ads,0,cc_entex);
433 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
436 adns__consistency(ads,0,cc_entex);
438 switch (ads->tcpstate) {
439 case server_disconnected:
442 case server_connecting:
443 if (fd != ads->tcpsocket) break;
444 assert(ads->tcprecv.used==0);
445 assert(ads->tcprecv_skip==0);
447 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
448 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
449 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
450 tcp_connected(ads,*now);
454 adns__tcp_broken(ads,"connect/read","sent data before first request");
457 if (errno==EINTR) continue;
458 if (errno_resources(errno)) { r= errno; goto xit; }
459 adns__tcp_broken(ads,"connect/read",strerror(errno));
463 if (fd != ads->tcpsocket) break;
464 while (ads->tcpsend.used) {
465 adns__sigpipe_protect(ads);
466 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
467 adns__sigpipe_unprotect(ads);
469 if (errno==EINTR) continue;
470 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
471 if (errno_resources(errno)) { r= errno; goto xit; }
472 adns__tcp_broken(ads,"write",strerror(errno));
475 ads->tcpsend.used -= r;
476 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
486 adns__consistency(ads,0,cc_entex);
490 int adns_processexceptional(adns_state ads, int fd,
491 const struct timeval *now) {
492 adns__consistency(ads,0,cc_entex);
493 switch (ads->tcpstate) {
494 case server_disconnected:
497 case server_connecting:
499 if (fd != ads->tcpsocket) break;
500 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
505 adns__consistency(ads,0,cc_entex);
509 static void fd_event(adns_state ads, int fd,
510 int revent, int pollflag,
511 int maxfd, const fd_set *fds,
512 int (*func)(adns_state, int fd,
513 const struct timeval *now),
514 struct timeval now, int *r_r) {
517 if (!(revent & pollflag)) return;
518 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
519 r= func(ads,fd,&now);
524 adns__diag(ads,-1,0,"process fd failed after select:"
525 " %s",strerror(errno));
526 adns_globalsystemfailure(ads);
531 void adns__fdevents(adns_state ads,
532 const struct pollfd *pollfds, int npollfds,
533 int maxfd, const fd_set *readfds,
534 const fd_set *writefds, const fd_set *exceptfds,
535 struct timeval now, int *r_r) {
538 for (i=0; i<npollfds; i++) {
540 if (fd >= maxfd) maxfd= fd+1;
541 revents= pollfds[i].revents;
542 #define EV(pollfl,fds,how) \
543 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
544 EV( POLLIN, readfds, readable );
545 EV( POLLOUT, writefds, writeable );
546 EV( POLLPRI, exceptfds, exceptional );
551 /* Wrappers for select(2). */
553 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
554 fd_set *writefds_io, fd_set *exceptfds_io,
555 struct timeval **tv_mod, struct timeval *tv_tobuf,
556 const struct timeval *now) {
557 struct timeval tv_nowbuf;
558 struct pollfd pollfds[MAX_POLLFDS];
559 int i, fd, maxfd, npollfds;
561 adns__consistency(ads,0,cc_entex);
563 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
564 /* The caller is planning to sleep. */
565 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
566 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
567 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
570 npollfds= adns__pollfds(ads,pollfds);
572 for (i=0; i<npollfds; i++) {
574 if (fd >= maxfd) maxfd= fd+1;
575 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
576 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
577 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
582 adns__consistency(ads,0,cc_entex);
585 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
586 const fd_set *writefds, const fd_set *exceptfds,
587 const struct timeval *now) {
588 struct timeval tv_buf;
589 struct pollfd pollfds[MAX_POLLFDS];
592 adns__consistency(ads,0,cc_entex);
593 adns__must_gettimeofday(ads,&now,&tv_buf);
595 adns_processtimeouts(ads,now);
597 npollfds= adns__pollfds(ads,pollfds);
598 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
601 maxfd,readfds,writefds,exceptfds,
604 adns__consistency(ads,0,cc_entex);
607 /* General helpful functions. */
609 void adns_globalsystemfailure(adns_state ads) {
610 adns__consistency(ads,0,cc_entex);
612 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
613 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
615 switch (ads->tcpstate) {
616 case server_connecting:
618 adns__tcp_broken(ads,0,0);
620 case server_disconnected:
626 adns__consistency(ads,0,cc_entex);
629 int adns_processany(adns_state ads) {
632 struct pollfd pollfds[MAX_POLLFDS];
635 adns__consistency(ads,0,cc_entex);
637 r= gettimeofday(&now,0);
638 if (!r) adns_processtimeouts(ads,&now);
640 /* We just use adns__fdevents to loop over the fd's trying them.
641 * This seems more sensible than calling select, since we're most
642 * likely just to want to do a read on one or two fds anyway.
644 npollfds= adns__pollfds(ads,pollfds);
645 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
651 adns__consistency(ads,0,cc_entex);
655 void adns__autosys(adns_state ads, struct timeval now) {
656 if (ads->iflags & adns_if_noautosys) return;
657 adns_processany(ads);
660 int adns__internal_check(adns_state ads,
661 adns_query *query_io,
662 adns_answer **answer,
668 if (ads->output.head) {
669 qu= ads->output.head;
670 } else if (ads->udpw.head || ads->tcpw.head) {
676 if (qu->id>=0) return EAGAIN;
678 LIST_UNLINK(ads->output,qu);
680 if (context_r) *context_r= qu->ctx.ext;
686 int adns_wait(adns_state ads,
687 adns_query *query_io,
688 adns_answer **answer_r,
691 fd_set readfds, writefds, exceptfds;
692 struct timeval tvbuf, *tvp;
694 adns__consistency(ads,*query_io,cc_entex);
696 r= adns__internal_check(ads,query_io,answer_r,context_r);
697 if (r != EAGAIN) break;
699 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
700 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
702 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
704 if (errno == EINTR) {
705 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
707 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
708 adns_globalsystemfailure(ads);
712 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
715 adns__consistency(ads,0,cc_entex);
719 int adns_check(adns_state ads,
720 adns_query *query_io,
721 adns_answer **answer_r,
726 adns__consistency(ads,*query_io,cc_entex);
727 r= gettimeofday(&now,0);
728 if (!r) adns__autosys(ads,now);
730 r= adns__internal_check(ads,query_io,answer_r,context_r);
731 adns__consistency(ads,0,cc_entex);