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__consistency(ads
,0,cc_entex
);
195 adns__timeouts(ads
, 0, tv_io
,tvbuf
, now
);
196 adns__consistency(ads
,0,cc_entex
);
199 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
) {
200 struct timeval tv_buf
;
202 adns__consistency(ads
,0,cc_entex
);
203 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
204 if (now
) adns__timeouts(ads
, 1, 0,0, *now
);
205 adns__consistency(ads
,0,cc_entex
);
208 /* fd handling functions. These are the top-level of the real work of
209 * reception and often transmission.
212 int adns__pollfds(adns_state ads
, struct pollfd pollfds_buf
[MAX_POLLFDS
]) {
213 /* Returns the number of entries filled in. Always zeroes revents. */
215 assert(MAX_POLLFDS
==2);
217 pollfds_buf
[0].fd
= ads
->udpsocket
;
218 pollfds_buf
[0].events
= POLLIN
;
219 pollfds_buf
[0].revents
= 0;
221 switch (ads
->tcpstate
) {
222 case server_disconnected
:
224 case server_connecting
:
225 pollfds_buf
[1].events
= POLLOUT
;
228 pollfds_buf
[1].events
= ads
->tcpsend
.used ? POLLIN
|POLLOUT
|POLLPRI
: POLLIN
|POLLPRI
;
233 pollfds_buf
[1].fd
= ads
->tcpsocket
;
237 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
) {
238 int skip
, want
, dgramlen
, r
, udpaddrlen
, serv
;
239 byte udpbuf
[DNS_MAXUDP
];
240 struct sockaddr_in udpaddr
;
242 adns__consistency(ads
,0,cc_entex
);
244 switch (ads
->tcpstate
) {
245 case server_disconnected
:
246 case server_connecting
:
249 if (fd
!= ads
->tcpsocket
) break;
252 if (ads
->tcprecv
.used
<skip
+2) {
255 dgramlen
= (ads
->tcprecv
.buf
[skip
]<<8) | ads
->tcprecv
.buf
[skip
+1];
256 if (ads
->tcprecv
.used
<skip
+2+dgramlen
) {
259 adns__procdgram(ads
,ads
->tcprecv
.buf
+skip
+2,dgramlen
,ads
->tcpserver
,1,*now
);
260 skip
+= 2+dgramlen
; continue;
263 ads
->tcprecv
.used
-= skip
;
264 memmove(ads
->tcprecv
.buf
,ads
->tcprecv
.buf
+skip
,ads
->tcprecv
.used
);
266 if (!adns__vbuf_ensure(&ads
->tcprecv
,want
)) { r
= ENOMEM
; goto xit
; }
267 assert(ads
->tcprecv
.used
<= ads
->tcprecv
.avail
);
268 if (ads
->tcprecv
.used
== ads
->tcprecv
.avail
) continue;
269 r
= read(ads
->tcpsocket
,
270 ads
->tcprecv
.buf
+ads
->tcprecv
.used
,
271 ads
->tcprecv
.avail
-ads
->tcprecv
.used
);
273 ads
->tcprecv
.used
+= r
;
276 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
277 if (errno
==EINTR
) continue;
278 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
280 adns__tcp_broken(ads
,"read",r?
strerror(errno
):"closed");
283 } /* never reached */
287 if (fd
== ads
->udpsocket
) {
289 udpaddrlen
= sizeof(udpaddr
);
290 r
= recvfrom(ads
->udpsocket
,udpbuf
,sizeof(udpbuf
),0,
291 (struct sockaddr
*)&udpaddr
,&udpaddrlen
);
293 if (errno
== EAGAIN
|| errno
== EWOULDBLOCK
) { r
= 0; goto xit
; }
294 if (errno
== EINTR
) continue;
295 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
296 adns__warn(ads
,-1,0,"datagram receive error: %s",strerror(errno
));
299 if (udpaddrlen
!= sizeof(udpaddr
)) {
300 adns__diag(ads
,-1,0,"datagram received with wrong address length %d"
301 " (expected %d)", udpaddrlen
,sizeof(udpaddr
));
304 if (udpaddr
.sin_family
!= AF_INET
) {
305 adns__diag(ads
,-1,0,"datagram received with wrong protocol family"
306 " %u (expected %u)",udpaddr
.sin_family
,AF_INET
);
309 if (ntohs(udpaddr
.sin_port
) != DNS_PORT
) {
310 adns__diag(ads
,-1,0,"datagram received from wrong port %u (expected %u)",
311 ntohs(udpaddr
.sin_port
),DNS_PORT
);
315 serv
< ads
->nservers
&&
316 ads
->servers
[serv
].addr
.s_addr
!= udpaddr
.sin_addr
.s_addr
;
318 if (serv
>= ads
->nservers
) {
319 adns__warn(ads
,-1,0,"datagram received from unknown nameserver %s",
320 inet_ntoa(udpaddr
.sin_addr
));
323 adns__procdgram(ads
,udpbuf
,r
,serv
,0,*now
);
328 adns__consistency(ads
,0,cc_entex
);
332 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
) {
335 adns__consistency(ads
,0,cc_entex
);
337 switch (ads
->tcpstate
) {
338 case server_disconnected
:
340 case server_connecting
:
341 if (fd
!= ads
->tcpsocket
) break;
342 assert(ads
->tcprecv
.used
==0);
344 if (!adns__vbuf_ensure(&ads
->tcprecv
,1)) { r
= ENOMEM
; goto xit
; }
345 r
= read(ads
->tcpsocket
,&ads
->tcprecv
.buf
,1);
346 if (r
==0 || (r
<0 && (errno
==EAGAIN
|| errno
==EWOULDBLOCK
))) {
347 tcp_connected(ads
,*now
);
351 adns__tcp_broken(ads
,"connect/read","sent data before first request");
354 if (errno
==EINTR
) continue;
355 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
356 adns__tcp_broken(ads
,"connect/read",strerror(errno
));
360 if (!(ads
->tcpsend
.used
&& fd
== ads
->tcpsocket
)) break;
362 adns__sigpipe_protect(ads
);
363 r
= write(ads
->tcpsocket
,ads
->tcpsend
.buf
,ads
->tcpsend
.used
);
364 adns__sigpipe_unprotect(ads
);
366 if (errno
==EINTR
) continue;
367 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
368 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
369 adns__tcp_broken(ads
,"write",strerror(errno
));
372 ads
->tcpsend
.used
-= r
;
373 memmove(ads
->tcpsend
.buf
,ads
->tcpsend
.buf
+r
,ads
->tcpsend
.used
);
381 adns__consistency(ads
,0,cc_entex
);
385 int adns_processexceptional(adns_state ads
, int fd
, const struct timeval
*now
) {
386 adns__consistency(ads
,0,cc_entex
);
387 switch (ads
->tcpstate
) {
388 case server_disconnected
:
390 case server_connecting
:
392 if (fd
!= ads
->tcpsocket
) break;
393 adns__tcp_broken(ads
,"poll/select","exceptional condition detected");
398 adns__consistency(ads
,0,cc_entex
);
402 static void fd_event(adns_state ads
, int fd
,
403 int revent
, int pollflag
,
404 int maxfd
, const fd_set
*fds
,
405 int (*func
)(adns_state
, int fd
, const struct timeval
*now
),
406 struct timeval now
, int *r_r
) {
409 if (!(revent
& pollflag
)) return;
410 if (fds
&& !(fd
<maxfd
&& FD_ISSET(fd
,fds
))) return;
411 r
= func(ads
,fd
,&now
);
416 adns__diag(ads
,-1,0,"process fd failed after select: %s",strerror(errno
));
417 adns_globalsystemfailure(ads
);
422 void adns__fdevents(adns_state ads
,
423 const struct pollfd
*pollfds
, int npollfds
,
424 int maxfd
, const fd_set
*readfds
,
425 const fd_set
*writefds
, const fd_set
*exceptfds
,
426 struct timeval now
, int *r_r
) {
429 for (i
=0; i
<npollfds
; i
++) {
431 if (fd
>= maxfd
) maxfd
= fd
+1;
432 revents
= pollfds
[i
].revents
;
433 fd_event(ads
,fd
, revents
,POLLIN
, maxfd
,readfds
, adns_processreadable
,now
,r_r
);
434 fd_event(ads
,fd
, revents
,POLLOUT
, maxfd
,writefds
, adns_processwriteable
,now
,r_r
);
435 fd_event(ads
,fd
, revents
,POLLPRI
, maxfd
,exceptfds
, adns_processexceptional
,now
,r_r
);
439 /* Wrappers for select(2). */
441 void adns_beforeselect(adns_state ads
, int *maxfd_io
, fd_set
*readfds_io
,
442 fd_set
*writefds_io
, fd_set
*exceptfds_io
,
443 struct timeval
**tv_mod
, struct timeval
*tv_tobuf
,
444 const struct timeval
*now
) {
445 struct timeval tv_nowbuf
;
446 struct pollfd pollfds
[MAX_POLLFDS
];
447 int i
, fd
, maxfd
, npollfds
;
449 adns__consistency(ads
,0,cc_entex
);
451 if (tv_mod
&& (!*tv_mod
|| (*tv_mod
)->tv_sec
|| (*tv_mod
)->tv_usec
)) {
452 /* The caller is planning to sleep. */
453 adns__must_gettimeofday(ads
,&now
,&tv_nowbuf
);
455 adns__timeouts(ads
, 1, tv_mod
,tv_tobuf
, *now
);
458 npollfds
= adns__pollfds(ads
,pollfds
);
460 for (i
=0; i
<npollfds
; i
++) {
462 if (fd
>= maxfd
) maxfd
= fd
+1;
463 if (pollfds
[i
].events
& POLLIN
) FD_SET(fd
,readfds_io
);
464 if (pollfds
[i
].events
& POLLOUT
) FD_SET(fd
,writefds_io
);
465 if (pollfds
[i
].events
& POLLPRI
) FD_SET(fd
,exceptfds_io
);
470 adns__consistency(ads
,0,cc_entex
);
473 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
474 const fd_set
*writefds
, const fd_set
*exceptfds
,
475 const struct timeval
*now
) {
476 struct timeval tv_buf
;
477 struct pollfd pollfds
[MAX_POLLFDS
];
480 adns__consistency(ads
,0,cc_entex
);
481 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
483 adns_processtimeouts(ads
,now
);
485 npollfds
= adns__pollfds(ads
,pollfds
);
486 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= POLLIN
|POLLOUT
|POLLPRI
;
489 maxfd
,readfds
,writefds
,exceptfds
,
492 adns__consistency(ads
,0,cc_entex
);
495 /* General helpful functions. */
497 void adns_globalsystemfailure(adns_state ads
) {
498 adns__consistency(ads
,0,cc_entex
);
500 while (ads
->timew
.head
) {
501 adns__query_fail(ads
->timew
.head
, adns_s_systemfail
);
504 switch (ads
->tcpstate
) {
505 case server_connecting
:
507 adns__tcp_closenext(ads
);
509 case server_disconnected
:
514 adns__consistency(ads
,0,cc_entex
);
517 int adns_processany(adns_state ads
) {
520 struct pollfd pollfds
[MAX_POLLFDS
];
523 adns__consistency(ads
,0,cc_entex
);
525 r
= gettimeofday(&now
,0);
526 if (!r
) adns_processtimeouts(ads
,&now
);
528 npollfds
= adns__pollfds(ads
,pollfds
);
534 adns__consistency(ads
,0,cc_entex
);
538 void adns__autosys(adns_state ads
, struct timeval now
) {
539 if (ads
->iflags
& adns_if_noautosys
) return;
540 adns_processany(ads
);
543 int adns__internal_check(adns_state ads
,
544 adns_query
*query_io
,
545 adns_answer
**answer
,
551 if (!ads
->output
.head
) return EWOULDBLOCK
;
552 qu
= ads
->output
.head
;
554 if (qu
->id
>=0) return EWOULDBLOCK
;
556 LIST_UNLINK(ads
->output
,qu
);
558 if (context_r
) *context_r
= qu
->ctx
.ext
;
564 int adns_wait(adns_state ads
,
565 adns_query
*query_io
,
566 adns_answer
**answer_r
,
569 fd_set readfds
, writefds
, exceptfds
;
570 struct timeval tvbuf
, *tvp
;
572 adns__consistency(ads
,*query_io
,cc_entex
);
574 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
575 if (r
!= EWOULDBLOCK
) break;
577 FD_ZERO(&readfds
); FD_ZERO(&writefds
); FD_ZERO(&exceptfds
);
578 adns_beforeselect(ads
,&maxfd
,&readfds
,&writefds
,&exceptfds
,&tvp
,&tvbuf
,0);
579 rsel
= select(maxfd
,&readfds
,&writefds
,&exceptfds
,tvp
);
581 if (errno
== EINTR
) {
582 if (ads
->iflags
& adns_if_eintr
) { r
= EINTR
; break; }
584 adns__diag(ads
,-1,0,"select failed in wait: %s",strerror(errno
));
585 adns_globalsystemfailure(ads
);
589 adns_afterselect(ads
,maxfd
,&readfds
,&writefds
,&exceptfds
,0);
592 adns__consistency(ads
,0,cc_entex
);
596 int adns_check(adns_state ads
,
597 adns_query
*query_io
,
598 adns_answer
**answer_r
,
603 adns__consistency(ads
,*query_io
,cc_entex
);
604 r
= gettimeofday(&now
,0);
605 if (!r
) adns__autosys(ads
,now
);
607 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
608 adns__consistency(ads
,0,cc_entex
);