4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
8 * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2, or (at your option)
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software Foundation,
22 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 #include <sys/types.h>
32 #include <sys/socket.h>
33 #include <netinet/in.h>
34 #include <arpa/inet.h>
38 /* TCP connection management. */
40 void adns__tcp_closenext(adns_state ads) {
44 close(ads->tcpsocket);
45 ads->tcpstate= server_disconnected;
46 ads->tcprecv.used= ads->tcpsend.used= 0;
47 ads->tcpserver= (serv+1)%ads->nservers;
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 adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why);
57 adns__tcp_closenext(ads);
59 for (qu= ads->timew.head; qu; qu= nqu) {
61 if (qu->state == query_tosend) continue;
62 assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
63 qu->state= query_tcpwait;
64 qu->tcpfailed |= (1<<serv);
65 if (qu->tcpfailed == (1<<ads->nservers)-1) {
66 LIST_UNLINK(ads->timew,qu);
67 adns__query_fail(qu,adns_s_allservfail);
72 static void tcp_connected(adns_state ads, struct timeval now) {
75 adns__debug(ads,ads->tcpserver,0,"TCP connected");
76 ads->tcpstate= server_ok;
77 for (qu= ads->timew.head; qu; qu= nqu) {
79 if (qu->state == query_tosend) continue;
80 assert (qu->state == query_tcpwait);
81 adns__query_tcp(qu,now);
85 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
87 struct sockaddr_in addr;
88 struct protoent *proto;
90 for (tries=0; tries<ads->nservers; tries++) {
91 if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
92 assert(ads->tcpstate == server_disconnected);
93 assert(!ads->tcpsend.used);
94 assert(!ads->tcprecv.used);
96 proto= getprotobyname("tcp");
97 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
98 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
100 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
103 r= adns__setnonblock(ads,fd);
105 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
109 memset(&addr,0,sizeof(addr));
110 addr.sin_family= AF_INET;
111 addr.sin_port= htons(DNS_PORT);
112 addr.sin_addr= ads->servers[ads->tcpserver].addr;
113 r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
115 ads->tcpstate= server_connecting;
116 if (r==0) { tcp_connected(ads,now); continue; }
117 if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
118 adns__tcp_broken(ads,"connect",strerror(errno));
122 /* Timeout handling functions. */
124 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
125 struct timeval *tv_buf) {
126 const struct timeval *now;
131 r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
132 adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
133 adns_globalsystemfailure(ads);
137 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
138 struct timeval maxto) {
139 struct timeval *rbuf;
144 *tvbuf= maxto; *tv_io= tvbuf;
146 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
148 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
149 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
152 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
153 struct timeval now, struct timeval maxtime) {
156 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
157 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
159 maxtime.tv_sec -= (now.tv_sec+2);
160 maxtime.tv_usec -= (now.tv_usec-2000000);
161 dr= ldiv(maxtime.tv_usec,1000000);
162 maxtime.tv_sec += dr.quot;
163 maxtime.tv_usec -= dr.quot*1000000;
164 if (maxtime.tv_sec<0) timerclear(&maxtime);
165 inter_maxto(tv_io,tvbuf,maxtime);
168 void adns__timeouts(adns_state ads, int act,
169 struct timeval **tv_io, struct timeval *tvbuf,
170 struct timeval now) {
173 for (qu= ads->timew.head; qu; qu= nqu) {
175 if (!timercmp(&now,&qu->timeout,>)) {
176 if (!tv_io) continue;
177 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
180 LIST_UNLINK(ads->timew,qu);
181 if (qu->state != query_tosend) {
182 adns__query_fail(qu,adns_s_timeout);
184 adns__query_send(qu,now);
186 nqu= ads->timew.head;
191 void adns_firsttimeout(adns_state ads,
192 struct timeval **tv_io, struct timeval *tvbuf,
193 struct timeval now) {
194 adns__timeouts(ads, 0, tv_io,tvbuf, now);
197 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
198 struct timeval tv_buf;
200 adns__must_gettimeofday(ads,&now,&tv_buf); if (!now) return;
201 adns__timeouts(ads, 1, 0,0, *now);
204 /* fd handling functions. These are the top-level of the real work of
205 * reception and often transmission.
208 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
209 /* Returns the number of entries filled in. Always zeroes revents. */
211 assert(MAX_POLLFDS==2);
213 pollfds_buf[0].fd= ads->udpsocket;
214 pollfds_buf[0].events= POLLIN;
215 pollfds_buf[0].revents= 0;
217 switch (ads->tcpstate) {
218 case server_disconnected:
220 case server_connecting:
221 pollfds_buf[1].events= POLLOUT;
224 pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
229 pollfds_buf[1].fd= ads->tcpsocket;
233 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
234 int skip, want, dgramlen, r, udpaddrlen, serv;
235 byte udpbuf[DNS_MAXUDP];
236 struct sockaddr_in udpaddr;
238 switch (ads->tcpstate) {
239 case server_disconnected:
240 case server_connecting:
243 if (fd != ads->tcpsocket) break;
246 if (ads->tcprecv.used<skip+2) {
249 dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
250 if (ads->tcprecv.used<skip+2+dgramlen) {
253 adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,1,*now);
254 skip+= 2+dgramlen; continue;
257 ads->tcprecv.used -= skip;
258 memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
260 if (!adns__vbuf_ensure(&ads->tcprecv,want)) return ENOMEM;
261 assert(ads->tcprecv.used <= ads->tcprecv.avail);
262 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
263 r= read(ads->tcpsocket,
264 ads->tcprecv.buf+ads->tcprecv.used,
265 ads->tcprecv.avail-ads->tcprecv.used);
267 ads->tcprecv.used+= r;
270 if (errno==EAGAIN || errno==EWOULDBLOCK) return 0;
271 if (errno==EINTR) continue;
272 if (errno_resources(errno)) return errno;
274 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
277 } /* never reached */
281 if (fd == ads->udpsocket) {
283 udpaddrlen= sizeof(udpaddr);
284 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
285 (struct sockaddr*)&udpaddr,&udpaddrlen);
287 if (errno == EAGAIN || errno == EWOULDBLOCK) return 0;
288 if (errno == EINTR) continue;
289 if (errno_resources(errno)) return errno;
290 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
293 if (udpaddrlen != sizeof(udpaddr)) {
294 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
295 " (expected %d)", udpaddrlen,sizeof(udpaddr));
298 if (udpaddr.sin_family != AF_INET) {
299 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
300 " %u (expected %u)",udpaddr.sin_family,AF_INET);
303 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
304 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
305 ntohs(udpaddr.sin_port),DNS_PORT);
309 serv < ads->nservers &&
310 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
312 if (serv >= ads->nservers) {
313 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
314 inet_ntoa(udpaddr.sin_addr));
317 adns__procdgram(ads,udpbuf,r,serv,0,*now);
323 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
326 switch (ads->tcpstate) {
327 case server_disconnected:
329 case server_connecting:
330 if (fd != ads->tcpsocket) break;
331 assert(ads->tcprecv.used==0);
333 if (!adns__vbuf_ensure(&ads->tcprecv,1)) return ENOMEM;
334 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
335 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
336 tcp_connected(ads,*now);
340 adns__tcp_broken(ads,"connect/read","sent data before first request");
343 if (errno==EINTR) continue;
344 if (errno_resources(errno)) return errno;
345 adns__tcp_broken(ads,"connect/read",strerror(errno));
349 if (!(ads->tcpsend.used && fd == ads->tcpsocket)) break;
351 adns__sigpipe_protect(ads);
352 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
353 adns__sigpipe_unprotect(ads);
355 if (errno==EINTR) continue;
356 if (errno==EAGAIN || errno==EWOULDBLOCK) return 0;
357 if (errno_resources(errno)) return errno;
358 adns__tcp_broken(ads,"write",strerror(errno));
361 ads->tcpsend.used -= r;
362 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
371 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
372 switch (ads->tcpstate) {
373 case server_disconnected:
375 case server_connecting:
377 if (fd != ads->tcpsocket) break;
378 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
386 static void fd_event(adns_state ads, int fd,
387 int revent, int pollflag,
388 int maxfd, const fd_set *fds,
389 int (*func)(adns_state, int fd, const struct timeval *now),
390 struct timeval now, int *r_r) {
393 if (!(revent & pollflag)) return;
394 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
395 r= func(ads,fd,&now);
400 adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
401 adns_globalsystemfailure(ads);
406 void adns__fdevents(adns_state ads,
407 const struct pollfd *pollfds, int npollfds,
408 int maxfd, const fd_set *readfds,
409 const fd_set *writefds, const fd_set *exceptfds,
410 struct timeval now, int *r_r) {
413 for (i=0; i<npollfds; i++) {
415 if (fd >= maxfd) maxfd= fd+1;
416 revents= pollfds[i].revents;
417 fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
418 fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
419 fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
423 /* Wrappers for select(2). */
425 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
426 fd_set *writefds_io, fd_set *exceptfds_io,
427 struct timeval **tv_mod, struct timeval *tv_tobuf,
428 const struct timeval *now) {
429 struct timeval tv_nowbuf;
430 struct pollfd pollfds[MAX_POLLFDS];
431 int i, fd, maxfd, npollfds;
433 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
434 /* The caller is planning to sleep. */
435 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
437 adns__timeouts(ads, 1, tv_mod,tv_tobuf, *now);
440 npollfds= adns__pollfds(ads,pollfds);
442 for (i=0; i<npollfds; i++) {
444 if (fd >= maxfd) maxfd= fd+1;
445 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
446 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
447 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
452 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
453 const fd_set *writefds, const fd_set *exceptfds,
454 const struct timeval *now) {
455 struct timeval tv_buf;
456 struct pollfd pollfds[MAX_POLLFDS];
459 adns__must_gettimeofday(ads,&now,&tv_buf);
461 adns_processtimeouts(ads,now);
463 npollfds= adns__pollfds(ads,pollfds);
464 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
467 maxfd,readfds,writefds,exceptfds,
471 /* General helpful functions. */
473 void adns_globalsystemfailure(adns_state ads) {
474 while (ads->timew.head) {
475 adns__query_fail(ads->timew.head, adns_s_systemfail);
478 switch (ads->tcpstate) {
479 case server_connecting:
481 adns__tcp_closenext(ads);
483 case server_disconnected:
490 int adns_processany(adns_state ads) {
493 struct pollfd pollfds[MAX_POLLFDS];
496 r= gettimeofday(&now,0);
497 if (!r) adns_processtimeouts(ads,&now);
499 npollfds= adns__pollfds(ads,pollfds);
507 void adns__autosys(adns_state ads, struct timeval now) {
508 if (ads->iflags & adns_if_noautosys) return;
509 adns_processany(ads);
512 static int internal_check(adns_state ads,
513 adns_query *query_io,
514 adns_answer **answer,
520 if (!ads->output.head) return EWOULDBLOCK;
521 qu= ads->output.head;
523 if (qu->id>=0) return EWOULDBLOCK;
525 LIST_UNLINK(ads->output,qu);
527 if (context_r) *context_r= qu->ctx.ext;
533 int adns_wait(adns_state ads,
534 adns_query *query_io,
535 adns_answer **answer_r,
538 fd_set readfds, writefds, exceptfds;
539 struct timeval tvbuf, *tvp;
542 r= internal_check(ads,query_io,answer_r,context_r);
543 if (r != EWOULDBLOCK) return r;
545 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
546 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
547 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
549 if (errno == EINTR) {
550 if (ads->iflags & adns_if_eintr) return EINTR;
552 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
553 adns_globalsystemfailure(ads);
557 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
562 int adns_check(adns_state ads,
563 adns_query *query_io,
564 adns_answer **answer_r,
569 r= gettimeofday(&now,0);
570 if (!r) adns__autosys(ads,now);
572 return internal_check(ads,query_io,answer_r,context_r);