4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
9 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
11 * It is part of adns, which is
12 * Copyright (C) 1997-1999 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) {
58 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
60 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
63 ads->tcpstate= server_broken;
64 ads->tcpserver= (serv+1)%ads->nservers;
67 static void tcp_connected(adns_state ads, struct timeval now) {
70 adns__debug(ads,ads->tcpserver,0,"TCP connected");
71 ads->tcpstate= server_ok;
72 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
74 assert(qu->state == query_tcpw);
75 adns__querysend_tcp(qu,now);
79 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
81 struct sockaddr_in addr;
82 struct protoent *proto;
84 for (tries=0; tries<ads->nservers; tries++) {
85 switch (ads->tcpstate) {
86 case server_connecting:
90 case server_disconnected:
96 assert(!ads->tcpsend.used);
97 assert(!ads->tcprecv.used);
98 assert(!ads->tcprecv_skip);
100 proto= getprotobyname("tcp");
101 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
102 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
104 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
107 r= adns__setnonblock(ads,fd);
109 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
113 memset(&addr,0,sizeof(addr));
114 addr.sin_family= AF_INET;
115 addr.sin_port= htons(DNS_PORT);
116 addr.sin_addr= ads->servers[ads->tcpserver].addr;
117 r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
119 ads->tcpstate= server_connecting;
120 if (r==0) { tcp_connected(ads,now); return; }
121 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
122 ads->tcptimeout= now;
123 timevaladd(&ads->tcptimeout,TCPCONNMS);
126 adns__tcp_broken(ads,"connect",strerror(errno));
127 ads->tcpstate= server_disconnected;
131 /* Timeout handling functions. */
133 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
134 struct timeval *tv_buf) {
135 const struct timeval *now;
140 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
141 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
142 adns_globalsystemfailure(ads);
146 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
147 struct timeval *rbuf;
152 if (!rbuf) { *tv_io= rbuf= tvbuf; }
157 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
158 struct timeval maxto) {
159 struct timeval *rbuf;
164 *tvbuf= maxto; *tv_io= tvbuf;
166 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
168 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
169 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
172 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
173 struct timeval now, struct timeval maxtime) {
177 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
178 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
180 maxtime.tv_sec -= (now.tv_sec+2);
181 maxtime.tv_usec -= (now.tv_usec-2000000);
182 dr= ldiv(maxtime.tv_usec,1000000);
183 maxtime.tv_sec += dr.quot;
184 maxtime.tv_usec -= dr.quot*1000000;
185 if (maxtime.tv_sec<0) timerclear(&maxtime);
186 inter_maxto(tv_io,tvbuf,maxtime);
189 static void timeouts_queue(adns_state ads, int act,
190 struct timeval **tv_io, struct timeval *tvbuf,
191 struct timeval now, struct query_queue *queue) {
194 for (qu= queue->head; qu; qu= nqu) {
196 if (!timercmp(&now,&qu->timeout,>)) {
197 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
199 if (!act) { inter_immed(tv_io,tvbuf); return; }
200 LIST_UNLINK(*queue,qu);
201 if (qu->state != query_tosend) {
202 adns__query_fail(qu,adns_s_timeout);
204 adns__query_send(qu,now);
211 static void tcp_events(adns_state ads, int act,
212 struct timeval **tv_io, struct timeval *tvbuf,
213 struct timeval now) {
217 switch (ads->tcpstate) {
219 if (!act) { inter_immed(tv_io,tvbuf); return; }
220 for (qu= ads->tcpw.head; qu; qu= nqu) {
222 assert(qu->state == query_tcpw);
223 if (qu->retries > ads->nservers) {
224 LIST_UNLINK(ads->tcpw,qu);
225 adns__query_fail(qu,adns_s_allservfail);
228 ads->tcpstate= server_disconnected;
229 case server_disconnected: /* fall through */
230 if (!ads->tcpw.head) return;
231 if (!act) { inter_immed(tv_io,tvbuf); return; }
232 adns__tcp_tryconnect(ads,now);
235 if (ads->tcpw.head) return;
236 if (!ads->tcptimeout.tv_sec) {
237 assert(!ads->tcptimeout.tv_usec);
238 ads->tcptimeout= now;
239 timevaladd(&ads->tcptimeout,TCPIDLEMS);
241 case server_connecting: /* fall through */
242 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
243 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
246 /* TCP timeout has happened */
247 switch (ads->tcpstate) {
248 case server_connecting: /* failed to connect */
249 adns__tcp_broken(ads,"unable to make connection","timed out");
251 case server_ok: /* idle timeout */
253 ads->tcpstate= server_disconnected;
267 void adns__timeouts(adns_state ads, int act,
268 struct timeval **tv_io, struct timeval *tvbuf,
269 struct timeval now) {
270 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
271 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
272 tcp_events(ads,act,tv_io,tvbuf,now);
275 void adns_firsttimeout(adns_state ads,
276 struct timeval **tv_io, struct timeval *tvbuf,
277 struct timeval now) {
278 adns__consistency(ads,0,cc_entex);
279 adns__timeouts(ads, 0, tv_io,tvbuf, now);
280 adns__consistency(ads,0,cc_entex);
283 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
284 struct timeval tv_buf;
286 adns__consistency(ads,0,cc_entex);
287 adns__must_gettimeofday(ads,&now,&tv_buf);
288 if (now) adns__timeouts(ads, 1, 0,0, *now);
289 adns__consistency(ads,0,cc_entex);
292 /* fd handling functions. These are the top-level of the real work of
293 * reception and often transmission.
296 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
297 /* Returns the number of entries filled in. Always zeroes revents. */
299 assert(MAX_POLLFDS==2);
301 pollfds_buf[0].fd= ads->udpsocket;
302 pollfds_buf[0].events= POLLIN;
303 pollfds_buf[0].revents= 0;
305 switch (ads->tcpstate) {
306 case server_disconnected:
309 case server_connecting:
310 pollfds_buf[1].events= POLLOUT;
313 pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
318 pollfds_buf[1].fd= ads->tcpsocket;
322 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
323 int want, dgramlen, r, udpaddrlen, serv, old_skip;
324 byte udpbuf[DNS_MAXUDP];
325 struct sockaddr_in udpaddr;
327 adns__consistency(ads,0,cc_entex);
329 switch (ads->tcpstate) {
330 case server_disconnected:
331 case server_connecting:
334 if (fd != ads->tcpsocket) break;
335 assert(!ads->tcprecv_skip);
337 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
338 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
339 ads->tcprecv.buf[ads->tcprecv_skip+1]);
340 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
341 old_skip= ads->tcprecv_skip;
342 ads->tcprecv_skip += 2+dgramlen;
343 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
344 dgramlen, ads->tcpserver, 1,*now);
352 ads->tcprecv.used -= ads->tcprecv_skip;
353 memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
354 ads->tcprecv_skip= 0;
355 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
356 assert(ads->tcprecv.used <= ads->tcprecv.avail);
357 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
358 r= read(ads->tcpsocket,
359 ads->tcprecv.buf+ads->tcprecv.used,
360 ads->tcprecv.avail-ads->tcprecv.used);
362 ads->tcprecv.used+= r;
365 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
366 if (errno==EINTR) continue;
367 if (errno_resources(errno)) { r= errno; goto xit; }
369 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
371 } while (ads->tcpstate == server_ok);
376 if (fd == ads->udpsocket) {
378 udpaddrlen= sizeof(udpaddr);
379 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
380 (struct sockaddr*)&udpaddr,&udpaddrlen);
382 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
383 if (errno == EINTR) continue;
384 if (errno_resources(errno)) { r= errno; goto xit; }
385 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
388 if (udpaddrlen != sizeof(udpaddr)) {
389 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
390 " (expected %d)", udpaddrlen,sizeof(udpaddr));
393 if (udpaddr.sin_family != AF_INET) {
394 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
395 " %u (expected %u)",udpaddr.sin_family,AF_INET);
398 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
399 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
400 ntohs(udpaddr.sin_port),DNS_PORT);
404 serv < ads->nservers &&
405 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
407 if (serv >= ads->nservers) {
408 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
409 inet_ntoa(udpaddr.sin_addr));
412 adns__procdgram(ads,udpbuf,r,serv,0,*now);
417 adns__consistency(ads,0,cc_entex);
421 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
424 adns__consistency(ads,0,cc_entex);
426 switch (ads->tcpstate) {
427 case server_disconnected:
429 case server_connecting:
430 if (fd != ads->tcpsocket) break;
431 assert(ads->tcprecv.used==0);
432 assert(ads->tcprecv_skip==0);
434 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
435 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
436 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
437 tcp_connected(ads,*now);
441 adns__tcp_broken(ads,"connect/read","sent data before first request");
444 if (errno==EINTR) continue;
445 if (errno_resources(errno)) { r= errno; goto xit; }
446 adns__tcp_broken(ads,"connect/read",strerror(errno));
450 if (!(ads->tcpsend.used && fd == ads->tcpsocket)) break;
452 adns__sigpipe_protect(ads);
453 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
454 adns__sigpipe_unprotect(ads);
456 if (errno==EINTR) continue;
457 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
458 if (errno_resources(errno)) { r= errno; goto xit; }
459 adns__tcp_broken(ads,"write",strerror(errno));
462 ads->tcpsend.used -= r;
463 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
471 adns__consistency(ads,0,cc_entex);
475 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
476 adns__consistency(ads,0,cc_entex);
477 switch (ads->tcpstate) {
478 case server_disconnected:
480 case server_connecting:
482 if (fd != ads->tcpsocket) break;
483 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
488 adns__consistency(ads,0,cc_entex);
492 static void fd_event(adns_state ads, int fd,
493 int revent, int pollflag,
494 int maxfd, const fd_set *fds,
495 int (*func)(adns_state, int fd, const struct timeval *now),
496 struct timeval now, int *r_r) {
499 if (!(revent & pollflag)) return;
500 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
501 r= func(ads,fd,&now);
506 adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
507 adns_globalsystemfailure(ads);
512 void adns__fdevents(adns_state ads,
513 const struct pollfd *pollfds, int npollfds,
514 int maxfd, const fd_set *readfds,
515 const fd_set *writefds, const fd_set *exceptfds,
516 struct timeval now, int *r_r) {
519 for (i=0; i<npollfds; i++) {
521 if (fd >= maxfd) maxfd= fd+1;
522 revents= pollfds[i].revents;
523 fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
524 fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
525 fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
529 /* Wrappers for select(2). */
531 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
532 fd_set *writefds_io, fd_set *exceptfds_io,
533 struct timeval **tv_mod, struct timeval *tv_tobuf,
534 const struct timeval *now) {
535 struct timeval tv_nowbuf;
536 struct pollfd pollfds[MAX_POLLFDS];
537 int i, fd, maxfd, npollfds;
539 adns__consistency(ads,0,cc_entex);
541 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
542 /* The caller is planning to sleep. */
543 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
544 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
545 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
548 npollfds= adns__pollfds(ads,pollfds);
550 for (i=0; i<npollfds; i++) {
552 if (fd >= maxfd) maxfd= fd+1;
553 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
554 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
555 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
560 adns__consistency(ads,0,cc_entex);
563 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
564 const fd_set *writefds, const fd_set *exceptfds,
565 const struct timeval *now) {
566 struct timeval tv_buf;
567 struct pollfd pollfds[MAX_POLLFDS];
570 adns__consistency(ads,0,cc_entex);
571 adns__must_gettimeofday(ads,&now,&tv_buf);
573 adns_processtimeouts(ads,now);
575 npollfds= adns__pollfds(ads,pollfds);
576 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
579 maxfd,readfds,writefds,exceptfds,
582 adns__consistency(ads,0,cc_entex);
585 /* General helpful functions. */
587 void adns_globalsystemfailure(adns_state ads) {
588 adns__consistency(ads,0,cc_entex);
590 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
591 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
593 switch (ads->tcpstate) {
594 case server_connecting:
596 adns__tcp_broken(ads,0,0);
598 case server_disconnected:
603 adns__consistency(ads,0,cc_entex);
606 int adns_processany(adns_state ads) {
609 struct pollfd pollfds[MAX_POLLFDS];
612 adns__consistency(ads,0,cc_entex);
614 r= gettimeofday(&now,0);
615 if (!r) adns_processtimeouts(ads,&now);
617 /* We just use adns__fdevents to loop over the fd's trying them.
618 * This seems more sensible than calling select, since we're most
619 * likely just to want to do a read on one or two fds anyway.
621 npollfds= adns__pollfds(ads,pollfds);
622 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events;
628 adns__consistency(ads,0,cc_entex);
632 void adns__autosys(adns_state ads, struct timeval now) {
633 if (ads->iflags & adns_if_noautosys) return;
634 adns_processany(ads);
637 int adns__internal_check(adns_state ads,
638 adns_query *query_io,
639 adns_answer **answer,
645 if (ads->output.head) {
646 qu= ads->output.head;
647 } else if (ads->udpw.head || ads->tcpw.head) {
653 if (qu->id>=0) return EAGAIN;
655 LIST_UNLINK(ads->output,qu);
657 if (context_r) *context_r= qu->ctx.ext;
663 int adns_wait(adns_state ads,
664 adns_query *query_io,
665 adns_answer **answer_r,
668 fd_set readfds, writefds, exceptfds;
669 struct timeval tvbuf, *tvp;
671 adns__consistency(ads,*query_io,cc_entex);
673 r= adns__internal_check(ads,query_io,answer_r,context_r);
674 if (r != EAGAIN) break;
676 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
677 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
679 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
681 if (errno == EINTR) {
682 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
684 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
685 adns_globalsystemfailure(ads);
689 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
692 adns__consistency(ads,0,cc_entex);
696 int adns_check(adns_state ads,
697 adns_query *query_io,
698 adns_answer **answer_r,
703 adns__consistency(ads,*query_io,cc_entex);
704 r= gettimeofday(&now,0);
705 if (!r) adns__autosys(ads,now);
707 r= adns__internal_check(ads,query_io,answer_r,context_r);
708 adns__consistency(ads,0,cc_entex);