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, 1998 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;
79 /* fixme: single TCP timeout, not once per server */
81 for (tries=0; tries<ads->nservers; tries++) {
82 if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
83 assert(ads->tcpstate == server_disconnected);
84 assert(!ads->tcpsend.used);
85 assert(!ads->tcprecv.used);
87 proto= getprotobyname("tcp");
88 if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
89 fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
91 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
94 r= adns__setnonblock(ads,fd);
96 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
100 memset(&addr,0,sizeof(addr));
101 addr.sin_family= AF_INET;
102 addr.sin_port= htons(DNS_PORT);
103 addr.sin_addr= ads->servers[ads->tcpserver].addr;
104 r= connect(fd,&addr,sizeof(addr));
106 ads->tcpstate= server_connecting;
107 if (r==0) { tcp_connected(ads,now); continue; }
108 if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
109 adns__tcp_broken(ads,"connect",strerror(errno));
113 /* `Interest' functions - find out which fd's we might be interested in,
114 * and when we want to be called back for a timeout.
117 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
118 struct timeval maxto) {
119 struct timeval *rbuf;
124 *tvbuf= maxto; *tv_io= tvbuf;
126 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
128 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
129 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
132 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
133 struct timeval now, struct timeval maxtime) {
136 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
137 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
139 maxtime.tv_sec -= (now.tv_sec+2);
140 maxtime.tv_usec -= (now.tv_usec-2000000);
141 dr= ldiv(maxtime.tv_usec,1000000);
142 maxtime.tv_sec += dr.quot;
143 maxtime.tv_usec -= dr.quot*1000000;
144 if (maxtime.tv_sec<0) timerclear(&maxtime);
145 inter_maxto(tv_io,tvbuf,maxtime);
148 static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
149 if (!maxfd || !fds) return;
150 if (fd>=*maxfd) *maxfd= fd+1;
154 static void checktimeouts(adns_state ads, struct timeval now,
155 struct timeval **tv_io, struct timeval *tvbuf) {
158 for (qu= ads->timew.head; qu; qu= nqu) {
160 if (timercmp(&now,&qu->timeout,>)) {
161 LIST_UNLINK(ads->timew,qu);
162 if (qu->state != query_udp) {
163 adns__query_fail(qu,adns_s_timeout);
165 adns__query_udp(qu,now);
168 inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
173 void adns_interest(adns_state ads, int *maxfd,
174 fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
175 struct timeval **tv_io, struct timeval *tvbuf) {
177 struct timeval tvto_lr;
180 /*fprintf(stderr,"adns_interest\n");*/
182 r= gettimeofday(&now,0);
184 adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s",
186 timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
187 inter_maxto(tv_io, tvbuf, tvto_lr);
189 checktimeouts(ads,now,tv_io,tvbuf);
192 inter_addfd(maxfd,readfds,ads->udpsocket);
194 switch (ads->tcpstate) {
195 case server_disconnected:
197 case server_connecting:
198 inter_addfd(maxfd,writefds,ads->tcpsocket);
201 inter_addfd(maxfd,readfds,ads->tcpsocket);
202 inter_addfd(maxfd,exceptfds,ads->tcpsocket);
203 if (ads->tcpsend.used) inter_addfd(maxfd,writefds,ads->tcpsocket);
210 /* Callback procedures - these do the real work of reception and timeout, etc. */
212 static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
213 return maxfd<0 || !fds ? 1 :
214 fd<maxfd && FD_ISSET(fd,fds);
217 static int internal_callback(adns_state ads, int maxfd,
218 const fd_set *readfds, const fd_set *writefds,
219 const fd_set *exceptfds,
220 struct timeval now) {
221 int skip, want, dgramlen, count, udpaddrlen, r, serv;
222 byte udpbuf[DNS_MAXUDP];
223 struct sockaddr_in udpaddr;
227 switch (ads->tcpstate) {
228 case server_disconnected:
230 case server_connecting:
231 if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
233 assert(ads->tcprecv.used==0);
234 if (!adns__vbuf_ensure(&ads->tcprecv,1)) return -1;
235 if (ads->tcprecv.buf) {
236 r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
237 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
238 tcp_connected(ads,now);
240 adns__tcp_broken(ads,"connect/read","sent data before first request");
241 } else if (errno!=EINTR) {
242 adns__tcp_broken(ads,"connect/read",strerror(errno));
248 count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
249 callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
250 (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
251 if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
254 if (ads->tcprecv.used<skip+2) {
257 dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
258 if (ads->tcprecv.used<skip+2+dgramlen) {
261 adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now);
262 skip+= 2+dgramlen; continue;
265 ads->tcprecv.used -= skip;
266 memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
268 if (!adns__vbuf_ensure(&ads->tcprecv,want)) return -1;
269 assert(ads->tcprecv.used <= ads->tcprecv.avail);
270 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
271 r= read(ads->tcpsocket,
272 ads->tcprecv.buf+ads->tcprecv.used,
273 ads->tcprecv.avail-ads->tcprecv.used);
275 ads->tcprecv.used+= r;
278 if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
279 if (errno==EINTR) continue;
281 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
285 } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
286 adns__tcp_broken(ads,"select","exceptional condition detected");
287 } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
288 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
290 if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
291 adns__tcp_broken(ads,"write",strerror(errno));
294 ads->tcpsend.used -= r;
295 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
303 if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
306 udpaddrlen= sizeof(udpaddr);
307 r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
309 if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
310 errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
311 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
314 if (udpaddrlen != sizeof(udpaddr)) {
315 adns__diag(ads,-1,0,"datagram received with wrong address length %d"
316 " (expected %d)", udpaddrlen,sizeof(udpaddr));
319 if (udpaddr.sin_family != AF_INET) {
320 adns__diag(ads,-1,0,"datagram received with wrong protocol family"
321 " %u (expected %u)",udpaddr.sin_family,AF_INET);
324 if (ntohs(udpaddr.sin_port) != DNS_PORT) {
325 adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
326 ntohs(udpaddr.sin_port),DNS_PORT);
330 serv < ads->nservers &&
331 ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
333 if (serv >= ads->nservers) {
334 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
335 inet_ntoa(udpaddr.sin_addr));
338 adns__procdgram(ads,udpbuf,r,serv,now);
344 int adns_callback(adns_state ads, int maxfd,
345 const fd_set *readfds, const fd_set *writefds,
346 const fd_set *exceptfds) {
350 r= gettimeofday(&now,0); if (r) return -1;
351 checktimeouts(ads,now,0,0);
352 return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now);
355 /* User-visible functions and their implementation. */
357 void adns__autosys(adns_state ads, struct timeval now) {
358 if (ads->iflags & adns_if_noautosys) return;
359 adns_callback(ads,-1,0,0,0);
362 static int internal_check(adns_state ads,
363 adns_query *query_io,
364 adns_answer **answer,
370 if (!ads->output.head) return EWOULDBLOCK;
371 qu= ads->output.head;
373 if (qu->id>=0) return EWOULDBLOCK;
375 LIST_UNLINK(ads->output,qu);
377 if (context_r) *context_r= qu->context.ext;
382 int adns_wait(adns_state ads,
383 adns_query *query_io,
384 adns_answer **answer_r,
386 int r, maxfd, rsel, rcb;
387 fd_set readfds, writefds, exceptfds;
388 struct timeval tvbuf, *tvp;
391 r= internal_check(ads,query_io,answer_r,context_r);
392 if (r != EWOULDBLOCK) return r;
394 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
395 adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
396 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
398 if (errno == EINTR && !(ads->iflags & adns_if_eintr)) continue;
401 rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
406 int adns_check(adns_state ads,
407 adns_query *query_io,
408 adns_answer **answer_r,
413 r= gettimeofday(&now,0); if (r) return errno;
414 adns__autosys(ads,now);
415 return internal_check(ads,query_io,answer_r,context_r);