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) 1997-2000,2003,2006,2014 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 3, 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.
32 #include <sys/types.h>
35 #include <sys/socket.h>
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
42 /* TCP connection management. */
44 static void tcp_close(adns_state ads) {
45 close(ads->tcpsocket);
47 ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
50 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
54 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
56 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
58 if (ads->tcpstate == server_connecting) {
59 /* Counts as a retry for all the queries waiting for TCP. */
60 for (qu= ads->tcpw.head; qu; qu= qu->next)
65 ads->tcpstate= server_broken;
66 ads->tcpserver= (serv+1)%ads->nservers;
69 static void tcp_connected(adns_state ads, struct timeval now) {
72 adns__debug(ads,ads->tcpserver,0,"TCP connected");
73 ads->tcpstate= server_ok;
74 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
76 assert(qu->state == query_tcpw);
77 adns__querysend_tcp(qu,now);
81 static void tcp_broken_events(adns_state ads) {
84 assert(ads->tcpstate == server_broken);
85 for (qu= ads->tcpw.head; qu; qu= nqu) {
87 assert(qu->state == query_tcpw);
88 if (qu->retries > ads->nservers) {
89 LIST_UNLINK(ads->tcpw,qu);
90 adns__query_fail(qu,adns_s_allservfail);
93 ads->tcpstate= server_disconnected;
96 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
99 struct protoent *proto;
101 for (tries=0; tries<ads->nservers; tries++) {
102 switch (ads->tcpstate) {
103 case server_connecting:
107 case server_disconnected:
113 assert(!ads->tcpsend.used);
114 assert(!ads->tcprecv.used);
115 assert(!ads->tcprecv_skip);
117 proto= getprotobyname("tcp");
119 adns__diag(ads,-1,0,"unable to find protocol no. for TCP !");
122 addr = &ads->servers[ads->tcpserver];
123 fd= socket(addr->addr.sa.sa_family, SOCK_STREAM, proto->p_proto);
125 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
128 r= adns__setnonblock(ads,fd);
130 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking:"
135 r= connect(fd,&addr->addr.sa,addr->len);
137 ads->tcpstate= server_connecting;
138 if (r==0) { tcp_connected(ads,now); return; }
139 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
140 ads->tcptimeout= now;
141 timevaladd(&ads->tcptimeout,TCPCONNMS);
144 adns__tcp_broken(ads,"connect",strerror(errno));
145 tcp_broken_events(ads);
149 /* Timeout handling functions. */
151 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
152 struct timeval *tv_buf) {
153 const struct timeval *now;
158 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
159 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
160 adns_globalsystemfailure(ads);
164 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
165 struct timeval *rbuf;
170 if (!rbuf) { *tv_io= rbuf= tvbuf; }
175 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
176 struct timeval maxto) {
177 struct timeval *rbuf;
182 *tvbuf= maxto; *tv_io= tvbuf;
184 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
186 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
187 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
190 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
191 struct timeval now, struct timeval maxtime) {
195 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
196 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
198 maxtime.tv_sec -= (now.tv_sec+2);
199 maxtime.tv_usec -= (now.tv_usec-2000000);
200 dr= ldiv(maxtime.tv_usec,1000000);
201 maxtime.tv_sec += dr.quot;
202 maxtime.tv_usec -= dr.quot*1000000;
203 if (maxtime.tv_sec<0) timerclear(&maxtime);
204 inter_maxto(tv_io,tvbuf,maxtime);
207 static void timeouts_queue(adns_state ads, int act,
208 struct timeval **tv_io, struct timeval *tvbuf,
209 struct timeval now, struct query_queue *queue) {
212 for (qu= queue->head; qu; qu= nqu) {
214 if (!timercmp(&now,&qu->timeout,>)) {
215 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
217 if (!act) { inter_immed(tv_io,tvbuf); return; }
218 LIST_UNLINK(*queue,qu);
219 if (qu->state != query_tosend) {
220 adns__query_fail(qu,adns_s_timeout);
222 adns__query_send(qu,now);
229 static void tcp_events(adns_state ads, int act,
230 struct timeval **tv_io, struct timeval *tvbuf,
231 struct timeval now) {
233 switch (ads->tcpstate) {
235 if (!act) { inter_immed(tv_io,tvbuf); return; }
236 tcp_broken_events(ads);
237 case server_disconnected: /* fall through */
238 if (!ads->tcpw.head) return;
239 if (!act) { inter_immed(tv_io,tvbuf); return; }
240 adns__tcp_tryconnect(ads,now);
243 if (ads->tcpw.head) return;
244 if (!ads->tcptimeout.tv_sec) {
245 assert(!ads->tcptimeout.tv_usec);
246 ads->tcptimeout= now;
247 timevaladd(&ads->tcptimeout,TCPIDLEMS);
249 case server_connecting: /* fall through */
250 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
251 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
254 /* TCP timeout has happened */
255 switch (ads->tcpstate) {
256 case server_connecting: /* failed to connect */
257 adns__tcp_broken(ads,"unable to make connection","timed out");
259 case server_ok: /* idle timeout */
261 ads->tcpstate= server_disconnected;
275 void adns__timeouts(adns_state ads, int act,
276 struct timeval **tv_io, struct timeval *tvbuf,
277 struct timeval now) {
278 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
279 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
280 tcp_events(ads,act,tv_io,tvbuf,now);
283 void adns_firsttimeout(adns_state ads,
284 struct timeval **tv_io, struct timeval *tvbuf,
285 struct timeval now) {
286 adns__consistency(ads,0,cc_entex);
287 adns__timeouts(ads, 0, tv_io,tvbuf, now);
288 adns__returning(ads,0);
291 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
292 struct timeval tv_buf;
294 adns__consistency(ads,0,cc_entex);
295 adns__must_gettimeofday(ads,&now,&tv_buf);
296 if (now) adns__timeouts(ads, 1, 0,0, *now);
297 adns__returning(ads,0);
300 /* fd handling functions. These are the top-level of the real work of
301 * reception and often transmission.
304 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
305 /* Returns the number of entries filled in. Always zeroes revents. */
307 #define ADD_POLLFD(wantfd, wantevents) do{ \
308 pollfds_buf[nwanted].fd= (wantfd); \
309 pollfds_buf[nwanted].events= (wantevents); \
310 pollfds_buf[nwanted].revents= 0; \
316 assert(MAX_POLLFDS == MAXUDP + 1);
318 for (i=0; i<ads->nudpsockets; i++)
319 ADD_POLLFD(ads->udpsockets[i].fd, POLLIN);
321 switch (ads->tcpstate) {
322 case server_disconnected:
325 case server_connecting:
326 ADD_POLLFD(ads->tcpsocket, POLLOUT);
329 ADD_POLLFD(ads->tcpsocket,
330 ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI);
335 assert(nwanted<=MAX_POLLFDS);
340 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
341 int want, dgramlen, r, i, udpaddrlen, serv, old_skip;
342 byte udpbuf[DNS_MAXUDP];
343 char addrbuf[ADNS_ADDR2TEXT_BUFLEN];
344 struct udpsocket *udp;
345 adns_sockaddr udpaddr;
347 adns__consistency(ads,0,cc_entex);
349 switch (ads->tcpstate) {
350 case server_disconnected:
352 case server_connecting:
355 if (fd != ads->tcpsocket) break;
356 assert(!ads->tcprecv_skip);
358 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
359 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
360 ads->tcprecv.buf[ads->tcprecv_skip+1]);
361 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
362 old_skip= ads->tcprecv_skip;
363 ads->tcprecv_skip += 2+dgramlen;
364 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
365 dgramlen, ads->tcpserver, 1,*now);
373 ads->tcprecv.used -= ads->tcprecv_skip;
374 memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
376 ads->tcprecv_skip= 0;
377 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
378 assert(ads->tcprecv.used <= ads->tcprecv.avail);
379 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
380 r= read(ads->tcpsocket,
381 ads->tcprecv.buf+ads->tcprecv.used,
382 ads->tcprecv.avail-ads->tcprecv.used);
384 ads->tcprecv.used+= r;
387 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
388 if (errno==EINTR) continue;
389 if (errno_resources(errno)) { r= errno; goto xit; }
391 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
393 } while (ads->tcpstate == server_ok);
398 for (i=0; i<ads->nudpsockets; i++) {
399 udp= &ads->udpsockets[i];
400 if (fd != udp->fd) continue;
402 udpaddrlen= sizeof(udpaddr);
403 r= recvfrom(fd,udpbuf,sizeof(udpbuf),0, &udpaddr.sa,&udpaddrlen);
405 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
406 if (errno == EINTR) continue;
407 if (errno_resources(errno)) { r= errno; goto xit; }
408 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
412 serv < ads->nservers &&
413 !adns__sockaddrs_equal(&udpaddr.sa,
414 &ads->servers[serv].addr.sa);
416 if (serv >= ads->nservers) {
417 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
418 adns__sockaddr_ntoa(&udpaddr.sa, addrbuf));
421 adns__procdgram(ads,udpbuf,r,serv,0,*now);
427 adns__returning(ads,0);
431 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
434 adns__consistency(ads,0,cc_entex);
436 switch (ads->tcpstate) {
437 case server_disconnected:
440 case server_connecting:
441 if (fd != ads->tcpsocket) break;
442 assert(ads->tcprecv.used==0);
443 assert(ads->tcprecv_skip==0);
445 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
446 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
447 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
448 tcp_connected(ads,*now);
452 adns__tcp_broken(ads,"connect/read","sent data before first request");
455 if (errno==EINTR) continue;
456 if (errno_resources(errno)) { r= errno; goto xit; }
457 adns__tcp_broken(ads,"connect/read",strerror(errno));
461 if (fd != ads->tcpsocket) break;
462 while (ads->tcpsend.used) {
463 adns__sigpipe_protect(ads);
464 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
465 adns__sigpipe_unprotect(ads);
467 if (errno==EINTR) continue;
468 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
469 if (errno_resources(errno)) { r= errno; goto xit; }
470 adns__tcp_broken(ads,"write",strerror(errno));
473 ads->tcpsend.used -= r;
474 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
484 adns__returning(ads,0);
488 int adns_processexceptional(adns_state ads, int fd,
489 const struct timeval *now) {
490 adns__consistency(ads,0,cc_entex);
491 switch (ads->tcpstate) {
492 case server_disconnected:
495 case server_connecting:
497 if (fd != ads->tcpsocket) break;
498 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
503 adns__returning(ads,0);
507 static void fd_event(adns_state ads, int fd,
508 int revent, int pollflag,
509 int maxfd, const fd_set *fds,
510 int (*func)(adns_state, int fd,
511 const struct timeval *now),
512 struct timeval now, int *r_r) {
515 if (!(revent & pollflag)) return;
516 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
517 r= func(ads,fd,&now);
522 adns__diag(ads,-1,0,"process fd failed after select:"
523 " %s",strerror(errno));
524 adns_globalsystemfailure(ads);
529 void adns__fdevents(adns_state ads,
530 const struct pollfd *pollfds, int npollfds,
531 int maxfd, const fd_set *readfds,
532 const fd_set *writefds, const fd_set *exceptfds,
533 struct timeval now, int *r_r) {
536 for (i=0; i<npollfds; i++) {
538 if (fd >= maxfd) maxfd= fd+1;
539 revents= pollfds[i].revents;
540 #define EV(pollfl,fds,how) \
541 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
542 EV( POLLIN, readfds, readable );
543 EV( POLLOUT, writefds, writeable );
544 EV( POLLPRI, exceptfds, exceptional );
549 /* Wrappers for select(2). */
551 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
552 fd_set *writefds_io, fd_set *exceptfds_io,
553 struct timeval **tv_mod, struct timeval *tv_tobuf,
554 const struct timeval *now) {
555 struct timeval tv_nowbuf;
556 struct pollfd pollfds[MAX_POLLFDS];
557 int i, fd, maxfd, npollfds;
559 adns__consistency(ads,0,cc_entex);
561 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
562 /* The caller is planning to sleep. */
563 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
564 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
565 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
568 npollfds= adns__pollfds(ads,pollfds);
570 for (i=0; i<npollfds; i++) {
572 if (fd >= maxfd) maxfd= fd+1;
573 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
574 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
575 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
580 adns__returning(ads,0);
583 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
584 const fd_set *writefds, const fd_set *exceptfds,
585 const struct timeval *now) {
586 struct timeval tv_buf;
587 struct pollfd pollfds[MAX_POLLFDS];
590 adns__consistency(ads,0,cc_entex);
591 adns__must_gettimeofday(ads,&now,&tv_buf);
593 adns_processtimeouts(ads,now);
595 npollfds= adns__pollfds(ads,pollfds);
596 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
599 maxfd,readfds,writefds,exceptfds,
602 adns__returning(ads,0);
605 /* General helpful functions. */
607 void adns_globalsystemfailure(adns_state ads) {
608 adns__consistency(ads,0,cc_entex);
610 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
611 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
613 switch (ads->tcpstate) {
614 case server_connecting:
616 adns__tcp_broken(ads,0,0);
618 case server_disconnected:
624 adns__returning(ads,0);
627 int adns_processany(adns_state ads) {
630 struct pollfd pollfds[MAX_POLLFDS];
633 adns__consistency(ads,0,cc_entex);
635 r= gettimeofday(&now,0);
636 if (!r) adns_processtimeouts(ads,&now);
638 /* We just use adns__fdevents to loop over the fd's trying them.
639 * This seems more sensible than calling select, since we're most
640 * likely just to want to do a read on one or two fds anyway.
642 npollfds= adns__pollfds(ads,pollfds);
643 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
649 adns__returning(ads,0);
653 void adns__autosys(adns_state ads, struct timeval now) {
654 if (ads->iflags & adns_if_noautosys) return;
655 adns_processany(ads);
658 int adns__internal_check(adns_state ads,
659 adns_query *query_io,
660 adns_answer **answer,
666 if (ads->output.head) {
667 qu= ads->output.head;
668 } else if (ads->udpw.head || ads->tcpw.head) {
674 if (qu->id>=0) return EAGAIN;
676 LIST_UNLINK(ads->output,qu);
678 if (context_r) *context_r= qu->ctx.ext;
684 int adns_wait(adns_state ads,
685 adns_query *query_io,
686 adns_answer **answer_r,
689 fd_set readfds, writefds, exceptfds;
690 struct timeval tvbuf, *tvp;
692 adns__consistency(ads,*query_io,cc_entex);
694 r= adns__internal_check(ads,query_io,answer_r,context_r);
695 if (r != EAGAIN) break;
697 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
698 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
700 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
702 if (errno == EINTR) {
703 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
705 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
706 adns_globalsystemfailure(ads);
710 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
713 adns__returning(ads,0);
717 int adns_check(adns_state ads,
718 adns_query *query_io,
719 adns_answer **answer_r,
724 adns__consistency(ads,*query_io,cc_entex);
725 r= gettimeofday(&now,0);
726 if (!r) adns__autosys(ads,now);
728 r= adns__internal_check(ads,query_io,answer_r,context_r);
729 adns__returning(ads,0);