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) 1999-2000 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 static void tcp_broken_events(adns_state ads) {
89 assert(ads->tcpstate == server_broken);
90 for (qu= ads->tcpw.head; qu; qu= nqu) {
92 assert(qu->state == query_tcpw);
93 if (qu->retries > ads->nservers) {
94 LIST_UNLINK(ads->tcpw,qu);
95 adns__query_fail(qu,adns_s_allservfail);
98 ads->tcpstate= server_disconnected;
101 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
103 struct sockaddr_in addr;
104 struct protoent *proto;
106 for (tries=0; tries<ads->nservers; tries++) {
107 switch (ads->tcpstate) {
108 case server_connecting:
112 case server_disconnected:
118 assert(!ads->tcpsend.used);
119 assert(!ads->tcprecv.used);
120 assert(!ads->tcprecv_skip);
122 proto= getprotobyname("tcp");
124 adns__diag(ads,-1,0,"unable to find protocol no. for TCP !");
127 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
129 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
132 r= adns__setnonblock(ads,fd);
134 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking:"
139 memset(&addr,0,sizeof(addr));
140 addr.sin_family= AF_INET;
141 addr.sin_port= htons(DNS_PORT);
142 addr.sin_addr= ads->servers[ads->tcpserver].addr;
143 r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
145 ads->tcpstate= server_connecting;
146 if (r==0) { tcp_connected(ads,now); return; }
147 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
148 ads->tcptimeout= now;
149 timevaladd(&ads->tcptimeout,TCPCONNMS);
152 adns__tcp_broken(ads,"connect",strerror(errno));
153 tcp_broken_events(ads);
157 /* Timeout handling functions. */
159 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
160 struct timeval *tv_buf) {
161 const struct timeval *now;
166 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
167 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
168 adns_globalsystemfailure(ads);
172 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
173 struct timeval *rbuf;
178 if (!rbuf) { *tv_io= rbuf= tvbuf; }
183 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
184 struct timeval maxto) {
185 struct timeval *rbuf;
190 *tvbuf= maxto; *tv_io= tvbuf;
192 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
194 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
195 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
198 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
199 struct timeval now, struct timeval maxtime) {
203 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
204 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
206 maxtime.tv_sec -= (now.tv_sec+2);
207 maxtime.tv_usec -= (now.tv_usec-2000000);
208 dr= ldiv(maxtime.tv_usec,1000000);
209 maxtime.tv_sec += dr.quot;
210 maxtime.tv_usec -= dr.quot*1000000;
211 if (maxtime.tv_sec<0) timerclear(&maxtime);
212 inter_maxto(tv_io,tvbuf,maxtime);
215 static void timeouts_queue(adns_state ads, int act,
216 struct timeval **tv_io, struct timeval *tvbuf,
217 struct timeval now, struct query_queue *queue) {
220 for (qu= queue->head; qu; qu= nqu) {
222 if (!timercmp(&now,&qu->timeout,>)) {
223 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
225 if (!act) { inter_immed(tv_io,tvbuf); return; }
226 LIST_UNLINK(*queue,qu);
227 if (qu->state != query_tosend) {
228 adns__query_fail(qu,adns_s_timeout);
230 adns__query_send(qu,now);
237 static void tcp_events(adns_state ads, int act,
238 struct timeval **tv_io, struct timeval *tvbuf,
239 struct timeval now) {
241 switch (ads->tcpstate) {
243 if (!act) { inter_immed(tv_io,tvbuf); return; }
244 tcp_broken_events(ads);
245 case server_disconnected: /* fall through */
246 if (!ads->tcpw.head) return;
247 if (!act) { inter_immed(tv_io,tvbuf); return; }
248 adns__tcp_tryconnect(ads,now);
251 if (ads->tcpw.head) return;
252 if (!ads->tcptimeout.tv_sec) {
253 assert(!ads->tcptimeout.tv_usec);
254 ads->tcptimeout= now;
255 timevaladd(&ads->tcptimeout,TCPIDLEMS);
257 case server_connecting: /* fall through */
258 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
259 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
262 /* TCP timeout has happened */
263 switch (ads->tcpstate) {
264 case server_connecting: /* failed to connect */
265 adns__tcp_broken(ads,"unable to make connection","timed out");
267 case server_ok: /* idle timeout */
269 ads->tcpstate= server_disconnected;
283 void adns__timeouts(adns_state ads, int act,
284 struct timeval **tv_io, struct timeval *tvbuf,
285 struct timeval now) {
286 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
287 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
288 tcp_events(ads,act,tv_io,tvbuf,now);
291 void adns_firsttimeout(adns_state ads,
292 struct timeval **tv_io, struct timeval *tvbuf,
293 struct timeval now) {
294 adns__consistency(ads,0,cc_entex);
295 adns__timeouts(ads, 0, tv_io,tvbuf, now);
296 adns__consistency(ads,0,cc_entex);
299 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
300 struct timeval tv_buf;
302 adns__consistency(ads,0,cc_entex);
303 adns__must_gettimeofday(ads,&now,&tv_buf);
304 if (now) adns__timeouts(ads, 1, 0,0, *now);
305 adns__consistency(ads,0,cc_entex);
308 /* fd handling functions. These are the top-level of the real work of
309 * reception and often transmission.
312 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
313 /* Returns the number of entries filled in. Always zeroes revents. */
315 assert(MAX_POLLFDS==2);
317 pollfds_buf[0].fd= ads->udpsocket;
318 pollfds_buf[0].events= POLLIN;
319 pollfds_buf[0].revents= 0;
321 switch (ads->tcpstate) {
322 case server_disconnected:
325 case server_connecting:
326 pollfds_buf[1].events= POLLOUT;
329 pollfds_buf[1].events=
330 ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
335 pollfds_buf[1].fd= ads->tcpsocket;
339 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
340 int want, dgramlen, r, udpaddrlen, serv, old_skip;
341 byte udpbuf[DNS_MAXUDP];
342 struct sockaddr_in udpaddr;
344 adns__consistency(ads,0,cc_entex);
346 switch (ads->tcpstate) {
347 case server_disconnected:
349 case server_connecting:
352 if (fd != ads->tcpsocket) break;
353 assert(!ads->tcprecv_skip);
355 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
356 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
357 ads->tcprecv.buf[ads->tcprecv_skip+1]);
358 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
359 old_skip= ads->tcprecv_skip;
360 ads->tcprecv_skip += 2+dgramlen;
361 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
362 dgramlen, ads->tcpserver, 1,*now);
370 ads->tcprecv.used -= ads->tcprecv_skip;
371 memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
373 ads->tcprecv_skip= 0;
374 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
375 assert(ads->tcprecv.used <= ads->tcprecv.avail);
376 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
377 r= read(ads->tcpsocket,
378 ads->tcprecv.buf+ads->tcprecv.used,
379 ads->tcprecv.avail-ads->tcprecv.used);
381 ads->tcprecv.used+= r;
384 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
385 if (errno==EINTR) continue;
386 if (errno_resources(errno)) { r= errno; goto xit; }
388 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
390 } while (ads->tcpstate == server_ok);
395 if (fd == ads->udpsocket) {
397 udpaddrlen= sizeof(udpaddr);
398 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
399 (struct sockaddr*)&udpaddr,&udpaddrlen);
401 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
402 if (errno == EINTR) continue;
403 if (errno_resources(errno)) { r= errno; goto xit; }
404 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
407 if (udpaddrlen != sizeof(udpaddr)) {
408 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
409 " (expected %lu)", udpaddrlen,
410 (unsigned long)sizeof(udpaddr));
413 if (udpaddr.sin_family != AF_INET) {
414 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
415 " %u (expected %u)",udpaddr.sin_family,AF_INET);
418 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
419 adns__diag(ads,-1,0,"datagram received from wrong port"
420 " %u (expected %u)", ntohs(udpaddr.sin_port),DNS_PORT);
424 serv < ads->nservers &&
425 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
427 if (serv >= ads->nservers) {
428 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
429 inet_ntoa(udpaddr.sin_addr));
432 adns__procdgram(ads,udpbuf,r,serv,0,*now);
437 adns__consistency(ads,0,cc_entex);
441 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
444 adns__consistency(ads,0,cc_entex);
446 switch (ads->tcpstate) {
447 case server_disconnected:
450 case server_connecting:
451 if (fd != ads->tcpsocket) break;
452 assert(ads->tcprecv.used==0);
453 assert(ads->tcprecv_skip==0);
455 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
456 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
457 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
458 tcp_connected(ads,*now);
462 adns__tcp_broken(ads,"connect/read","sent data before first request");
465 if (errno==EINTR) continue;
466 if (errno_resources(errno)) { r= errno; goto xit; }
467 adns__tcp_broken(ads,"connect/read",strerror(errno));
471 if (fd != ads->tcpsocket) break;
472 while (ads->tcpsend.used) {
473 adns__sigpipe_protect(ads);
474 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
475 adns__sigpipe_unprotect(ads);
477 if (errno==EINTR) continue;
478 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
479 if (errno_resources(errno)) { r= errno; goto xit; }
480 adns__tcp_broken(ads,"write",strerror(errno));
483 ads->tcpsend.used -= r;
484 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
494 adns__consistency(ads,0,cc_entex);
498 int adns_processexceptional(adns_state ads, int fd,
499 const struct timeval *now) {
500 adns__consistency(ads,0,cc_entex);
501 switch (ads->tcpstate) {
502 case server_disconnected:
505 case server_connecting:
507 if (fd != ads->tcpsocket) break;
508 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
513 adns__consistency(ads,0,cc_entex);
517 static void fd_event(adns_state ads, int fd,
518 int revent, int pollflag,
519 int maxfd, const fd_set *fds,
520 int (*func)(adns_state, int fd,
521 const struct timeval *now),
522 struct timeval now, int *r_r) {
525 if (!(revent & pollflag)) return;
526 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
527 r= func(ads,fd,&now);
532 adns__diag(ads,-1,0,"process fd failed after select:"
533 " %s",strerror(errno));
534 adns_globalsystemfailure(ads);
539 void adns__fdevents(adns_state ads,
540 const struct pollfd *pollfds, int npollfds,
541 int maxfd, const fd_set *readfds,
542 const fd_set *writefds, const fd_set *exceptfds,
543 struct timeval now, int *r_r) {
546 for (i=0; i<npollfds; i++) {
548 if (fd >= maxfd) maxfd= fd+1;
549 revents= pollfds[i].revents;
550 #define EV(pollfl,fds,how) \
551 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
552 EV( POLLIN, readfds, readable );
553 EV( POLLOUT, writefds, writeable );
554 EV( POLLPRI, exceptfds, exceptional );
559 /* Wrappers for select(2). */
561 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
562 fd_set *writefds_io, fd_set *exceptfds_io,
563 struct timeval **tv_mod, struct timeval *tv_tobuf,
564 const struct timeval *now) {
565 struct timeval tv_nowbuf;
566 struct pollfd pollfds[MAX_POLLFDS];
567 int i, fd, maxfd, npollfds;
569 adns__consistency(ads,0,cc_entex);
571 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
572 /* The caller is planning to sleep. */
573 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
574 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
575 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
578 npollfds= adns__pollfds(ads,pollfds);
580 for (i=0; i<npollfds; i++) {
582 if (fd >= maxfd) maxfd= fd+1;
583 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
584 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
585 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
590 adns__consistency(ads,0,cc_entex);
593 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
594 const fd_set *writefds, const fd_set *exceptfds,
595 const struct timeval *now) {
596 struct timeval tv_buf;
597 struct pollfd pollfds[MAX_POLLFDS];
600 adns__consistency(ads,0,cc_entex);
601 adns__must_gettimeofday(ads,&now,&tv_buf);
603 adns_processtimeouts(ads,now);
605 npollfds= adns__pollfds(ads,pollfds);
606 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
609 maxfd,readfds,writefds,exceptfds,
612 adns__consistency(ads,0,cc_entex);
615 /* General helpful functions. */
617 void adns_globalsystemfailure(adns_state ads) {
618 adns__consistency(ads,0,cc_entex);
620 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
621 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
623 switch (ads->tcpstate) {
624 case server_connecting:
626 adns__tcp_broken(ads,0,0);
628 case server_disconnected:
634 adns__consistency(ads,0,cc_entex);
637 int adns_processany(adns_state ads) {
640 struct pollfd pollfds[MAX_POLLFDS];
643 adns__consistency(ads,0,cc_entex);
645 r= gettimeofday(&now,0);
646 if (!r) adns_processtimeouts(ads,&now);
648 /* We just use adns__fdevents to loop over the fd's trying them.
649 * This seems more sensible than calling select, since we're most
650 * likely just to want to do a read on one or two fds anyway.
652 npollfds= adns__pollfds(ads,pollfds);
653 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
659 adns__consistency(ads,0,cc_entex);
663 void adns__autosys(adns_state ads, struct timeval now) {
664 if (ads->iflags & adns_if_noautosys) return;
665 adns_processany(ads);
668 int adns__internal_check(adns_state ads,
669 adns_query *query_io,
670 adns_answer **answer,
676 if (ads->output.head) {
677 qu= ads->output.head;
678 } else if (ads->udpw.head || ads->tcpw.head) {
684 if (qu->id>=0) return EAGAIN;
686 LIST_UNLINK(ads->output,qu);
688 if (context_r) *context_r= qu->ctx.ext;
694 int adns_wait(adns_state ads,
695 adns_query *query_io,
696 adns_answer **answer_r,
699 fd_set readfds, writefds, exceptfds;
700 struct timeval tvbuf, *tvp;
702 adns__consistency(ads,*query_io,cc_entex);
704 r= adns__internal_check(ads,query_io,answer_r,context_r);
705 if (r != EAGAIN) break;
707 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
708 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
710 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
712 if (errno == EINTR) {
713 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
715 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
716 adns_globalsystemfailure(ads);
720 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
723 adns__consistency(ads,0,cc_entex);
727 int adns_check(adns_state ads,
728 adns_query *query_io,
729 adns_answer **answer_r,
734 adns__consistency(ads,*query_io,cc_entex);
735 r= gettimeofday(&now,0);
736 if (!r) adns__autosys(ads,now);
738 r= adns__internal_check(ads,query_io,answer_r,context_r);
739 adns__consistency(ads,0,cc_entex);