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>
43 /* TCP connection management. */
45 static void tcp_close(adns_state ads) {
49 close(ads->tcpsocket);
51 ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
54 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
57 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
59 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
62 ads->tcpstate= server_broken;
63 ads->tcpserver= (serv+1)%ads->nservers;
66 static void tcp_connected(adns_state ads, struct timeval now) {
69 adns__debug(ads,ads->tcpserver,0,"TCP connected");
70 ads->tcpstate= server_ok;
71 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
73 assert(qu->state == query_tcpw);
74 adns__querysend_tcp(qu,now);
78 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
80 struct sockaddr_in addr;
81 struct protoent *proto;
83 for (tries=0; tries<ads->nservers; tries++) {
84 switch (ads->tcpstate) {
85 case server_connecting:
89 case server_disconnected:
95 assert(!ads->tcpsend.used);
96 assert(!ads->tcprecv.used);
97 assert(!ads->tcprecv_skip);
99 proto= getprotobyname("tcp");
100 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
101 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
103 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
106 r= adns__setnonblock(ads,fd);
108 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
112 memset(&addr,0,sizeof(addr));
113 addr.sin_family= AF_INET;
114 addr.sin_port= htons(DNS_PORT);
115 addr.sin_addr= ads->servers[ads->tcpserver].addr;
116 r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
118 ads->tcpstate= server_connecting;
119 if (r==0) { tcp_connected(ads,now); return; }
120 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
121 ads->tcptimeout= now;
122 timevaladd(&ads->tcptimeout,TCPCONNMS);
125 adns__tcp_broken(ads,"connect",strerror(errno));
126 ads->tcpstate= server_disconnected;
130 /* Timeout handling functions. */
132 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
133 struct timeval *tv_buf) {
134 const struct timeval *now;
139 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
140 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
141 adns_globalsystemfailure(ads);
145 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
146 struct timeval maxto) {
147 struct timeval *rbuf;
152 *tvbuf= maxto; *tv_io= tvbuf;
154 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
156 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
157 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
160 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
161 struct timeval now, struct timeval maxtime) {
165 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
166 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
168 maxtime.tv_sec -= (now.tv_sec+2);
169 maxtime.tv_usec -= (now.tv_usec-2000000);
170 dr= ldiv(maxtime.tv_usec,1000000);
171 maxtime.tv_sec += dr.quot;
172 maxtime.tv_usec -= dr.quot*1000000;
173 if (maxtime.tv_sec<0) timerclear(&maxtime);
174 inter_maxto(tv_io,tvbuf,maxtime);
177 static void timeouts_queue(adns_state ads, int act,
178 struct timeval **tv_io, struct timeval *tvbuf,
179 struct timeval now, struct query_queue *queue) {
182 for (qu= queue->head; qu; qu= nqu) {
184 if (!timercmp(&now,&qu->timeout,>)) {
185 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
193 LIST_UNLINK(*queue,qu);
194 if (qu->state != query_tosend) {
195 adns__query_fail(qu,adns_s_timeout);
197 adns__query_send(qu,now);
204 static void tcp_events(adns_state ads, int act,
205 struct timeval **tv_io, struct timeval *tvbuf,
206 struct timeval now) {
210 switch (ads->tcpstate) {
212 for (qu= ads->tcpw.head; qu; qu= nqu) {
214 assert(qu->state == query_tcpw);
215 if (qu->retries > ads->nservers) {
216 LIST_UNLINK(ads->tcpw,qu);
217 adns__query_fail(qu,adns_s_allservfail);
220 ads->tcpstate= server_disconnected;
221 case server_disconnected: /* fall through */
222 if (!ads->tcpw.head) return;
223 adns__tcp_tryconnect(ads,now);
226 if (ads->tcpw.head) return;
227 if (!ads->tcptimeout.tv_sec) {
228 assert(!ads->tcptimeout.tv_usec);
229 ads->tcptimeout= now;
230 timevaladd(&ads->tcptimeout,TCPIDLEMS);
232 case server_connecting: /* fall through */
233 if (!timercmp(&now,&ads->tcptimeout,>)) {
234 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
237 /* TCP timeout has happened */
238 switch (ads->tcpstate) {
239 case server_connecting: /* failed to connect */
240 adns__tcp_broken(ads,"unable to make connection","timed out");
242 case server_ok: /* idle timeout */
244 ads->tcpstate= server_disconnected;
257 void adns__timeouts(adns_state ads, int act,
258 struct timeval **tv_io, struct timeval *tvbuf,
259 struct timeval now) {
260 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
261 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
262 tcp_events(ads,act,tv_io,tvbuf,now);
265 void adns_firsttimeout(adns_state ads,
266 struct timeval **tv_io, struct timeval *tvbuf,
267 struct timeval now) {
268 adns__consistency(ads,0,cc_entex);
269 adns__timeouts(ads, 0, tv_io,tvbuf, now);
270 adns__consistency(ads,0,cc_entex);
273 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
274 struct timeval tv_buf;
276 adns__consistency(ads,0,cc_entex);
277 adns__must_gettimeofday(ads,&now,&tv_buf);
278 if (now) adns__timeouts(ads, 1, 0,0, *now);
279 adns__consistency(ads,0,cc_entex);
282 /* fd handling functions. These are the top-level of the real work of
283 * reception and often transmission.
286 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
287 /* Returns the number of entries filled in. Always zeroes revents. */
289 assert(MAX_POLLFDS==2);
291 pollfds_buf[0].fd= ads->udpsocket;
292 pollfds_buf[0].events= POLLIN;
293 pollfds_buf[0].revents= 0;
295 switch (ads->tcpstate) {
296 case server_disconnected:
298 case server_connecting:
299 pollfds_buf[1].events= POLLOUT;
302 pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
307 pollfds_buf[1].fd= ads->tcpsocket;
311 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
312 int want, dgramlen, r, udpaddrlen, serv, old_skip;
313 byte udpbuf[DNS_MAXUDP];
314 struct sockaddr_in udpaddr;
316 adns__consistency(ads,0,cc_entex);
318 switch (ads->tcpstate) {
319 case server_disconnected:
320 case server_connecting:
323 if (fd != ads->tcpsocket) break;
324 assert(!ads->tcprecv_skip);
326 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
327 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
328 ads->tcprecv.buf[ads->tcprecv_skip+1]);
329 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
330 old_skip= ads->tcprecv_skip;
331 ads->tcprecv_skip += 2+dgramlen;
332 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
333 dgramlen, ads->tcpserver, 1,*now);
341 ads->tcprecv.used -= ads->tcprecv_skip;
342 memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
343 ads->tcprecv_skip= 0;
344 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
345 assert(ads->tcprecv.used <= ads->tcprecv.avail);
346 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
347 r= read(ads->tcpsocket,
348 ads->tcprecv.buf+ads->tcprecv.used,
349 ads->tcprecv.avail-ads->tcprecv.used);
351 ads->tcprecv.used+= r;
354 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
355 if (errno==EINTR) continue;
356 if (errno_resources(errno)) { r= errno; goto xit; }
358 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
361 } /* never reached */
365 if (fd == ads->udpsocket) {
367 udpaddrlen= sizeof(udpaddr);
368 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
369 (struct sockaddr*)&udpaddr,&udpaddrlen);
371 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
372 if (errno == EINTR) continue;
373 if (errno_resources(errno)) { r= errno; goto xit; }
374 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
377 if (udpaddrlen != sizeof(udpaddr)) {
378 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
379 " (expected %d)", udpaddrlen,sizeof(udpaddr));
382 if (udpaddr.sin_family != AF_INET) {
383 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
384 " %u (expected %u)",udpaddr.sin_family,AF_INET);
387 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
388 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
389 ntohs(udpaddr.sin_port),DNS_PORT);
393 serv < ads->nservers &&
394 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
396 if (serv >= ads->nservers) {
397 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
398 inet_ntoa(udpaddr.sin_addr));
401 adns__procdgram(ads,udpbuf,r,serv,0,*now);
406 adns__consistency(ads,0,cc_entex);
410 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
413 adns__consistency(ads,0,cc_entex);
415 switch (ads->tcpstate) {
416 case server_disconnected:
418 case server_connecting:
419 if (fd != ads->tcpsocket) break;
420 assert(ads->tcprecv.used==0);
421 assert(ads->tcprecv_skip==0);
423 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
424 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
425 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
426 tcp_connected(ads,*now);
430 adns__tcp_broken(ads,"connect/read","sent data before first request");
433 if (errno==EINTR) continue;
434 if (errno_resources(errno)) { r= errno; goto xit; }
435 adns__tcp_broken(ads,"connect/read",strerror(errno));
439 if (!(ads->tcpsend.used && fd == ads->tcpsocket)) break;
441 adns__sigpipe_protect(ads);
442 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
443 adns__sigpipe_unprotect(ads);
445 if (errno==EINTR) continue;
446 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
447 if (errno_resources(errno)) { r= errno; goto xit; }
448 adns__tcp_broken(ads,"write",strerror(errno));
451 ads->tcpsend.used -= r;
452 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
460 adns__consistency(ads,0,cc_entex);
464 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
465 adns__consistency(ads,0,cc_entex);
466 switch (ads->tcpstate) {
467 case server_disconnected:
469 case server_connecting:
471 if (fd != ads->tcpsocket) break;
472 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
477 adns__consistency(ads,0,cc_entex);
481 static void fd_event(adns_state ads, int fd,
482 int revent, int pollflag,
483 int maxfd, const fd_set *fds,
484 int (*func)(adns_state, int fd, const struct timeval *now),
485 struct timeval now, int *r_r) {
488 if (!(revent & pollflag)) return;
489 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
490 r= func(ads,fd,&now);
495 adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
496 adns_globalsystemfailure(ads);
501 void adns__fdevents(adns_state ads,
502 const struct pollfd *pollfds, int npollfds,
503 int maxfd, const fd_set *readfds,
504 const fd_set *writefds, const fd_set *exceptfds,
505 struct timeval now, int *r_r) {
508 for (i=0; i<npollfds; i++) {
510 if (fd >= maxfd) maxfd= fd+1;
511 revents= pollfds[i].revents;
512 fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
513 fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
514 fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
518 /* Wrappers for select(2). */
520 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
521 fd_set *writefds_io, fd_set *exceptfds_io,
522 struct timeval **tv_mod, struct timeval *tv_tobuf,
523 const struct timeval *now) {
524 struct timeval tv_nowbuf;
525 struct pollfd pollfds[MAX_POLLFDS];
526 int i, fd, maxfd, npollfds;
528 adns__consistency(ads,0,cc_entex);
530 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
531 /* The caller is planning to sleep. */
532 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
534 adns__timeouts(ads, 1, tv_mod,tv_tobuf, *now);
537 npollfds= adns__pollfds(ads,pollfds);
539 for (i=0; i<npollfds; i++) {
541 if (fd >= maxfd) maxfd= fd+1;
542 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
543 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
544 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
549 adns__consistency(ads,0,cc_entex);
552 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
553 const fd_set *writefds, const fd_set *exceptfds,
554 const struct timeval *now) {
555 struct timeval tv_buf;
556 struct pollfd pollfds[MAX_POLLFDS];
559 adns__consistency(ads,0,cc_entex);
560 adns__must_gettimeofday(ads,&now,&tv_buf);
562 adns_processtimeouts(ads,now);
564 npollfds= adns__pollfds(ads,pollfds);
565 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
568 maxfd,readfds,writefds,exceptfds,
571 adns__consistency(ads,0,cc_entex);
574 /* General helpful functions. */
576 void adns_globalsystemfailure(adns_state ads) {
577 adns__consistency(ads,0,cc_entex);
579 while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
580 while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
582 switch (ads->tcpstate) {
583 case server_connecting:
585 adns__tcp_broken(ads,0,0);
587 case server_disconnected:
592 adns__consistency(ads,0,cc_entex);
595 int adns_processany(adns_state ads) {
598 struct pollfd pollfds[MAX_POLLFDS];
601 adns__consistency(ads,0,cc_entex);
603 r= gettimeofday(&now,0);
604 if (!r) adns_processtimeouts(ads,&now);
606 /* We just use adns__fdevents to loop over the fd's trying them.
607 * This seems more sensible than calling select, since we're most
608 * likely just to want to do a read on one or two fds anyway.
610 npollfds= adns__pollfds(ads,pollfds);
611 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events;
617 adns__consistency(ads,0,cc_entex);
621 void adns__autosys(adns_state ads, struct timeval now) {
622 if (ads->iflags & adns_if_noautosys) return;
623 adns_processany(ads);
626 int adns__internal_check(adns_state ads,
627 adns_query *query_io,
628 adns_answer **answer,
634 if (ads->output.head) {
635 qu= ads->output.head;
636 } else if (ads->udpw.head || ads->tcpw.head) {
642 if (qu->id>=0) return EAGAIN;
644 LIST_UNLINK(ads->output,qu);
646 if (context_r) *context_r= qu->ctx.ext;
652 int adns_wait(adns_state ads,
653 adns_query *query_io,
654 adns_answer **answer_r,
657 fd_set readfds, writefds, exceptfds;
658 struct timeval tvbuf, *tvp;
660 adns__consistency(ads,*query_io,cc_entex);
662 r= adns__internal_check(ads,query_io,answer_r,context_r);
663 if (r != EAGAIN) break;
665 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
666 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
667 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
669 if (errno == EINTR) {
670 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
672 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
673 adns_globalsystemfailure(ads);
677 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
680 adns__consistency(ads,0,cc_entex);
684 int adns_check(adns_state ads,
685 adns_query *query_io,
686 adns_answer **answer_r,
691 adns__consistency(ads,*query_io,cc_entex);
692 r= gettimeofday(&now,0);
693 if (!r) adns__autosys(ads,now);
695 r= adns__internal_check(ads,query_io,answer_r,context_r);
696 adns__consistency(ads,0,cc_entex);