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.
30 #include <arpa/inet.h>
34 /* TCP connection management */
36 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
40 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
42 adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why);
43 close(ads->tcpsocket);
44 ads->tcpstate= server_disconnected;
46 for (qu= ads->timew.head; qu; qu= nqu) {
48 if (qu->state == query_udp) continue;
49 assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
50 qu->state= query_tcpwait;
51 qu->tcpfailed |= (1<<serv);
52 if (qu->tcpfailed == (1<<ads->nservers)-1) {
53 LIST_UNLINK(ads->timew,qu);
54 adns__query_fail(qu,adns_s_allservfail);
58 ads->tcprecv.used= ads->tcpsend.used= 0;
59 ads->tcpserver= (serv+1)%ads->nservers;
62 static void tcp_connected(adns_state ads, struct timeval now) {
65 adns__debug(ads,ads->tcpserver,0,"TCP connected");
66 ads->tcpstate= server_ok;
67 for (qu= ads->timew.head; qu; qu= nqu) {
69 if (qu->state == query_udp) continue;
70 assert (qu->state == query_tcpwait);
71 adns__query_tcp(qu,now);
75 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
77 struct sockaddr_in addr;
78 struct protoent *proto;
80 for (tries=0; tries<ads->nservers; tries++) {
81 if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
82 assert(ads->tcpstate == server_disconnected);
83 assert(!ads->tcpsend.used);
84 assert(!ads->tcprecv.used);
86 proto= getprotobyname("tcp");
87 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
88 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
90 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
93 r= adns__setnonblock(ads,fd);
95 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
99 memset(&addr,0,sizeof(addr));
100 addr.sin_family= AF_INET;
101 addr.sin_port= htons(DNS_PORT);
102 addr.sin_addr= ads->servers[ads->tcpserver].addr;
103 r= connect(fd,&addr,sizeof(addr));
105 ads->tcpstate= server_connecting;
106 if (r==0) { tcp_connected(ads,now); continue; }
107 if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
108 adns__tcp_broken(ads,"connect",strerror(errno));
112 /* `Interest' functions - find out which fd's we might be interested in,
113 * and when we want to be called back for a timeout.
116 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
117 struct timeval maxto) {
118 struct timeval *rbuf;
123 *tvbuf= maxto; *tv_io= tvbuf;
125 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
127 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
128 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
131 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
132 struct timeval now, struct timeval maxtime) {
135 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
136 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
138 maxtime.tv_sec -= (now.tv_sec+2);
139 maxtime.tv_usec -= (now.tv_usec-2000000);
140 dr= ldiv(maxtime.tv_usec,1000000);
141 maxtime.tv_sec += dr.quot;
142 maxtime.tv_usec -= dr.quot*1000000;
143 if (maxtime.tv_sec<0) timerclear(&maxtime);
144 inter_maxto(tv_io,tvbuf,maxtime);
147 static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
148 if (!maxfd || !fds) return;
149 if (fd>=*maxfd) *maxfd= fd+1;
153 static void checktimeouts(adns_state ads, struct timeval now,
154 struct timeval **tv_io, struct timeval *tvbuf) {
157 for (qu= ads->timew.head; qu; qu= nqu) {
159 if (timercmp(&now,&qu->timeout,>)) {
160 LIST_UNLINK(ads->timew,qu);
161 if (qu->state != query_udp) {
162 adns__query_fail(qu,adns_s_timeout);
164 adns__query_udp(qu,now);
167 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
172 static void checkfds(adns_state ads, int *maxfd,
173 fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
174 int avail, struct pollfd *buf, int *count_r) {
178 inter_addfd(ads->udpsocket,maxfd,readfds);
179 poll_addfd(ads->udpsocket,avail,buf,&count,POLLIN);
181 switch (ads->tcpstate) {
182 case server_disconnected:
184 case server_connecting:
185 inter_addfd(ads->tcpsocket,maxfd,writefds);
186 poll_addfd(ads->tcpsocket,avail,buf,&count,POLLOUT);
189 inter_addfd(ads->tcpsocket,maxfd,readfds);
190 inter_addfd(ads->tcpsocket,maxfd,exceptfds);
191 if (ads->tcpsend.used) inter_addfd(ads->tcpsocket,maxfd,writefds);
192 poll_addfd(ads->tcpsocket,avail,buf,&count,
193 ads->tcpsend.used ? POLLIN|POLLOUT : POLLIN);
200 struct pollfd *adns_pollfds(adns_state ads, struct pollfd *buf,
201 int *len_io, int *timeout_io) {
202 struct timeval now, tvbuf, *tvp;
205 r= gettimeofday(&now,0);
208 timeout= *timeout_io;
212 tvbuf.tv_sec= now.tv_sec + (timeout/1000);
213 tvbuf.tv_usec= now.tv_usec + (timeout%1000)*1000;
214 if (tvbuf.tv_sec >= 1000000) {
216 tvbuf.tv_usec -= 1000000;
220 checktimouts(ads,now,&tvp,&tvbuf);
223 assert(tvbuf.tv_sec<INT_MAX/1000);
224 *timeout_io= (tvp->tv_sec - now.tv_sec)*1000 + (tvp->tv_usec - now.tv_usec)/1000;
231 buf= ads->pollfdsbuf;
234 buf= ads->pollfdsbuf= malloc(sizeof(struct pollfd)*avail);
238 checkfds(ads, 0,0,0,0, avail,buf,len_io);
239 if (*len_io > avail) { errno= ENOSPC; return 0; }
244 void adns_interest(adns_state ads, int *maxfd,
245 fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
246 struct timeval **tv_io, struct timeval *tvbuf) {
248 struct timeval tvto_lr;
251 /*fprintf(stderr,"adns_interest\n");*/
253 r= gettimeofday(&now,0);
255 adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s",
257 timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
258 inter_maxto(tv_io, tvbuf, tvto_lr);
260 checktimeouts(ads,now,tv_io,tvbuf);
263 checkfds(ads, maxfd,readfds,writefds,exceptfds, 0,0,0);
266 /* Callback procedures - these do the real work of reception and timeout, etc. */
268 static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
269 return maxfd<0 || !fds ? 1 :
270 fd<maxfd && FD_ISSET(fd,fds);
273 static int internal_callback(adns_state ads, int maxfd,
274 const fd_set *readfds, const fd_set *writefds,
275 const fd_set *exceptfds,
276 struct timeval now) {
277 int skip, want, dgramlen, count, udpaddrlen, r, serv;
278 byte udpbuf[DNS_MAXUDP];
279 struct sockaddr_in udpaddr;
283 switch (ads->tcpstate) {
284 case server_disconnected:
286 case server_connecting:
287 if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
289 assert(ads->tcprecv.used==0);
290 if (!adns__vbuf_ensure(&ads->tcprecv,1)) return -1;
291 if (ads->tcprecv.buf) {
292 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
293 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
294 tcp_connected(ads,now);
296 adns__tcp_broken(ads,"connect/read","sent data before first request");
297 } else if (errno!=EINTR) {
298 adns__tcp_broken(ads,"connect/read",strerror(errno));
304 count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
305 callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
306 (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
307 if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
310 if (ads->tcprecv.used<skip+2) {
313 dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
314 if (ads->tcprecv.used<skip+2+dgramlen) {
317 adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now);
318 skip+= 2+dgramlen; continue;
321 ads->tcprecv.used -= skip;
322 memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
324 if (!adns__vbuf_ensure(&ads->tcprecv,want)) return -1;
325 assert(ads->tcprecv.used <= ads->tcprecv.avail);
326 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
327 r= read(ads->tcpsocket,
328 ads->tcprecv.buf+ads->tcprecv.used,
329 ads->tcprecv.avail-ads->tcprecv.used);
331 ads->tcprecv.used+= r;
334 if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
335 if (errno==EINTR) continue;
337 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
341 } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
342 adns__tcp_broken(ads,"select","exceptional condition detected");
343 } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
344 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
346 if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
347 adns__tcp_broken(ads,"write",strerror(errno));
350 ads->tcpsend.used -= r;
351 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
359 if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
362 udpaddrlen= sizeof(udpaddr);
363 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
365 if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
366 errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
367 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
370 if (udpaddrlen != sizeof(udpaddr)) {
371 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
372 " (expected %d)", udpaddrlen,sizeof(udpaddr));
375 if (udpaddr.sin_family != AF_INET) {
376 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
377 " %u (expected %u)",udpaddr.sin_family,AF_INET);
380 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
381 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
382 ntohs(udpaddr.sin_port),DNS_PORT);
386 serv < ads->nservers &&
387 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
389 if (serv >= ads->nservers) {
390 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
391 inet_ntoa(udpaddr.sin_addr));
394 adns__procdgram(ads,udpbuf,r,serv,now);
400 int adns_callback(adns_state ads, int maxfd,
401 const fd_set *readfds, const fd_set *writefds,
402 const fd_set *exceptfds) {
406 r= gettimeofday(&now,0); if (r) return -1;
407 checktimeouts(ads,now,0,0);
408 return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now);
411 /* User-visible functions and their implementation. */
413 void adns__autosys(adns_state ads, struct timeval now) {
414 if (ads->iflags & adns_if_noautosys) return;
415 adns_callback(ads,-1,0,0,0);
418 static int internal_check(adns_state ads,
419 adns_query *query_io,
420 adns_answer **answer,
426 if (!ads->output.head) return EWOULDBLOCK;
427 qu= ads->output.head;
429 if (qu->id>=0) return EWOULDBLOCK;
431 LIST_UNLINK(ads->output,qu);
433 if (context_r) *context_r= qu->ctx.ext;
438 int adns_wait(adns_state ads,
439 adns_query *query_io,
440 adns_answer **answer_r,
442 int r, maxfd, rsel, rcb;
443 fd_set readfds, writefds, exceptfds;
444 struct timeval tvbuf, *tvp;
447 r= internal_check(ads,query_io,answer_r,context_r);
448 if (r != EWOULDBLOCK) return r;
450 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
451 adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
452 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
454 if (errno == EINTR && !(ads->iflags & adns_if_eintr)) continue;
457 rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
462 int adns_check(adns_state ads,
463 adns_query *query_io,
464 adns_answer **answer_r,
469 r= gettimeofday(&now,0); if (r) return errno;
470 adns__autosys(ads,now);
471 return internal_check(ads,query_io,answer_r,context_r);