4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
8 * This file is part of adns, which is
9 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
10 * Copyright (C) 1999-2000,2003,2006 Tony Finch
11 * Copyright (C) 1991 Massachusetts Institute of Technology
12 * (See the file INSTALL for full details.)
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, write to the Free Software Foundation,
26 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
33 #include <sys/types.h>
36 #include <sys/socket.h>
37 #include <netinet/in.h>
38 #include <arpa/inet.h>
43 /* TCP connection management. */
45 static void tcp_close(adns_state ads
) {
46 close(ads
->tcpsocket
);
48 ads
->tcprecv
.used
= ads
->tcprecv_skip
= ads
->tcpsend
.used
= 0;
51 void adns__tcp_broken(adns_state ads
, const char *what
, const char *why
) {
55 assert(ads
->tcpstate
== server_connecting
|| ads
->tcpstate
== server_ok
);
57 if (what
) adns__warn(ads
,serv
,0,"TCP connection failed: %s: %s",what
,why
);
59 if (ads
->tcpstate
== server_connecting
) {
60 /* Counts as a retry for all the queries waiting for TCP. */
61 for (qu
= ads
->tcpw
.head
; qu
; qu
= qu
->next
)
66 ads
->tcpstate
= server_broken
;
67 ads
->tcpserver
= (serv
+1)%ads
->nservers
;
70 static void tcp_connected(adns_state ads
, struct timeval now
) {
73 adns__debug(ads
,ads
->tcpserver
,0,"TCP connected");
74 ads
->tcpstate
= server_ok
;
75 for (qu
= ads
->tcpw
.head
; qu
&& ads
->tcpstate
== server_ok
; qu
= nqu
) {
77 assert(qu
->state
== query_tcpw
);
78 adns__querysend_tcp(qu
,now
);
82 static void tcp_broken_events(adns_state ads
) {
85 assert(ads
->tcpstate
== server_broken
);
86 for (qu
= ads
->tcpw
.head
; qu
; qu
= nqu
) {
88 assert(qu
->state
== query_tcpw
);
89 if (qu
->retries
> ads
->nservers
) {
90 LIST_UNLINK(ads
->tcpw
,qu
);
91 adns__query_fail(qu
,adns_s_allservfail
);
94 ads
->tcpstate
= server_disconnected
;
97 void adns__tcp_tryconnect(adns_state ads
, struct timeval now
) {
100 struct protoent
*proto
;
102 for (tries
=0; tries
<ads
->nservers
; tries
++) {
103 switch (ads
->tcpstate
) {
104 case server_connecting
:
108 case server_disconnected
:
114 assert(!ads
->tcpsend
.used
);
115 assert(!ads
->tcprecv
.used
);
116 assert(!ads
->tcprecv_skip
);
118 proto
= getprotobyname("tcp");
120 adns__diag(ads
,-1,0,"unable to find protocol no. for TCP !");
123 addr
= &ads
->servers
[ads
->tcpserver
];
124 fd
= socket(addr
->addr
.sa
.sa_family
, SOCK_STREAM
, proto
->p_proto
);
126 adns__diag(ads
,-1,0,"cannot create TCP socket: %s",strerror(errno
));
129 r
= adns__setnonblock(ads
,fd
);
131 adns__diag(ads
,-1,0,"cannot make TCP socket nonblocking:"
136 r
= connect(fd
,&addr
->addr
.sa
,addr
->len
);
138 ads
->tcpstate
= server_connecting
;
139 if (r
==0) { tcp_connected(ads
,now
); return; }
140 if (errno
== EWOULDBLOCK
|| errno
== EINPROGRESS
) {
141 ads
->tcptimeout
= now
;
142 timevaladd(&ads
->tcptimeout
,TCPCONNMS
);
145 adns__tcp_broken(ads
,"connect",strerror(errno
));
146 tcp_broken_events(ads
);
150 /* Timeout handling functions. */
152 void adns__must_gettimeofday(adns_state ads
, const struct timeval
**now_io
,
153 struct timeval
*tv_buf
) {
154 const struct timeval
*now
;
159 r
= gettimeofday(tv_buf
,0); if (!r
) { *now_io
= tv_buf
; return; }
160 adns__diag(ads
,-1,0,"gettimeofday failed: %s",strerror(errno
));
161 adns_globalsystemfailure(ads
);
165 static void inter_immed(struct timeval
**tv_io
, struct timeval
*tvbuf
) {
166 struct timeval
*rbuf
;
171 if (!rbuf
) { *tv_io
= rbuf
= tvbuf
; }
176 static void inter_maxto(struct timeval
**tv_io
, struct timeval
*tvbuf
,
177 struct timeval maxto
) {
178 struct timeval
*rbuf
;
183 *tvbuf
= maxto
; *tv_io
= tvbuf
;
185 if (timercmp(rbuf
,&maxto
,>)) *rbuf
= maxto
;
187 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
188 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
191 static void inter_maxtoabs(struct timeval
**tv_io
, struct timeval
*tvbuf
,
192 struct timeval now
, struct timeval maxtime
) {
196 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
197 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
199 maxtime
.tv_sec
-= (now
.tv_sec
+2);
200 maxtime
.tv_usec
-= (now
.tv_usec
-2000000);
201 dr
= ldiv(maxtime
.tv_usec
,1000000);
202 maxtime
.tv_sec
+= dr
.quot
;
203 maxtime
.tv_usec
-= dr
.quot
*1000000;
204 if (maxtime
.tv_sec
<0) timerclear(&maxtime
);
205 inter_maxto(tv_io
,tvbuf
,maxtime
);
208 static void timeouts_queue(adns_state ads
, int act
,
209 struct timeval
**tv_io
, struct timeval
*tvbuf
,
210 struct timeval now
, struct query_queue
*queue
) {
213 for (qu
= queue
->head
; qu
; qu
= nqu
) {
215 if (!timercmp(&now
,&qu
->timeout
,>)) {
216 inter_maxtoabs(tv_io
,tvbuf
,now
,qu
->timeout
);
218 if (!act
) { inter_immed(tv_io
,tvbuf
); return; }
219 LIST_UNLINK(*queue
,qu
);
220 if (qu
->state
!= query_tosend
) {
221 adns__query_fail(qu
,adns_s_timeout
);
223 adns__query_send(qu
,now
);
230 static void tcp_events(adns_state ads
, int act
,
231 struct timeval
**tv_io
, struct timeval
*tvbuf
,
232 struct timeval now
) {
234 switch (ads
->tcpstate
) {
236 if (!act
) { inter_immed(tv_io
,tvbuf
); return; }
237 tcp_broken_events(ads
);
238 case server_disconnected
: /* fall through */
239 if (!ads
->tcpw
.head
) return;
240 if (!act
) { inter_immed(tv_io
,tvbuf
); return; }
241 adns__tcp_tryconnect(ads
,now
);
244 if (ads
->tcpw
.head
) return;
245 if (!ads
->tcptimeout
.tv_sec
) {
246 assert(!ads
->tcptimeout
.tv_usec
);
247 ads
->tcptimeout
= now
;
248 timevaladd(&ads
->tcptimeout
,TCPIDLEMS
);
250 case server_connecting
: /* fall through */
251 if (!act
|| !timercmp(&now
,&ads
->tcptimeout
,>)) {
252 inter_maxtoabs(tv_io
,tvbuf
,now
,ads
->tcptimeout
);
255 /* TCP timeout has happened */
256 switch (ads
->tcpstate
) {
257 case server_connecting
: /* failed to connect */
258 adns__tcp_broken(ads
,"unable to make connection","timed out");
260 case server_ok
: /* idle timeout */
262 ads
->tcpstate
= server_disconnected
;
276 void adns__timeouts(adns_state ads
, int act
,
277 struct timeval
**tv_io
, struct timeval
*tvbuf
,
278 struct timeval now
) {
279 timeouts_queue(ads
,act
,tv_io
,tvbuf
,now
, &ads
->udpw
);
280 timeouts_queue(ads
,act
,tv_io
,tvbuf
,now
, &ads
->tcpw
);
281 tcp_events(ads
,act
,tv_io
,tvbuf
,now
);
284 void adns_firsttimeout(adns_state ads
,
285 struct timeval
**tv_io
, struct timeval
*tvbuf
,
286 struct timeval now
) {
287 adns__consistency(ads
,0,cc_entex
);
288 adns__timeouts(ads
, 0, tv_io
,tvbuf
, now
);
289 adns__returning(ads
,0);
292 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
) {
293 struct timeval tv_buf
;
295 adns__consistency(ads
,0,cc_entex
);
296 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
297 if (now
) adns__timeouts(ads
, 1, 0,0, *now
);
298 adns__returning(ads
,0);
301 /* fd handling functions. These are the top-level of the real work of
302 * reception and often transmission.
305 int adns__pollfds(adns_state ads
, struct pollfd pollfds_buf
[MAX_POLLFDS
]) {
306 /* Returns the number of entries filled in. Always zeroes revents. */
308 #define ADD_POLLFD(wantfd, wantevents) do{ \
309 pollfds_buf[nwanted].fd= (wantfd); \
310 pollfds_buf[nwanted].events= (wantevents); \
311 pollfds_buf[nwanted].revents= 0; \
317 assert(MAX_POLLFDS
== MAXUDP
+ 1);
319 for (i
=0; i
<ads
->nudp
; i
++)
320 ADD_POLLFD(ads
->udpsocket
[i
].fd
, POLLIN
);
322 switch (ads
->tcpstate
) {
323 case server_disconnected
:
326 case server_connecting
:
327 ADD_POLLFD(ads
->tcpsocket
, POLLOUT
);
330 ADD_POLLFD(ads
->tcpsocket
,
331 ads
->tcpsend
.used ? POLLIN
|POLLOUT
|POLLPRI
: POLLIN
|POLLPRI
);
336 assert(nwanted
<=MAX_POLLFDS
);
341 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
) {
342 int want
, dgramlen
, r
, i
, udpaddrlen
, serv
, old_skip
;
343 byte udpbuf
[DNS_MAXUDP
];
344 char addrbuf
[ADNS_ADDR2TEXT_BUFLEN
];
345 struct udpsocket
*udp
;
346 adns_sockaddr udpaddr
;
348 adns__consistency(ads
,0,cc_entex
);
350 switch (ads
->tcpstate
) {
351 case server_disconnected
:
353 case server_connecting
:
356 if (fd
!= ads
->tcpsocket
) break;
357 assert(!ads
->tcprecv_skip
);
359 if (ads
->tcprecv
.used
>= ads
->tcprecv_skip
+2) {
360 dgramlen
= ((ads
->tcprecv
.buf
[ads
->tcprecv_skip
]<<8) |
361 ads
->tcprecv
.buf
[ads
->tcprecv_skip
+1]);
362 if (ads
->tcprecv
.used
>= ads
->tcprecv_skip
+2+dgramlen
) {
363 old_skip
= ads
->tcprecv_skip
;
364 ads
->tcprecv_skip
+= 2+dgramlen
;
365 adns__procdgram(ads
, ads
->tcprecv
.buf
+old_skip
+2,
366 dgramlen
, ads
->tcpserver
, 1,*now
);
374 ads
->tcprecv
.used
-= ads
->tcprecv_skip
;
375 memmove(ads
->tcprecv
.buf
, ads
->tcprecv
.buf
+ads
->tcprecv_skip
,
377 ads
->tcprecv_skip
= 0;
378 if (!adns__vbuf_ensure(&ads
->tcprecv
,want
)) { r
= ENOMEM
; goto xit
; }
379 assert(ads
->tcprecv
.used
<= ads
->tcprecv
.avail
);
380 if (ads
->tcprecv
.used
== ads
->tcprecv
.avail
) continue;
381 r
= read(ads
->tcpsocket
,
382 ads
->tcprecv
.buf
+ads
->tcprecv
.used
,
383 ads
->tcprecv
.avail
-ads
->tcprecv
.used
);
385 ads
->tcprecv
.used
+= r
;
388 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
389 if (errno
==EINTR
) continue;
390 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
392 adns__tcp_broken(ads
,"read",r?
strerror(errno
):"closed");
394 } while (ads
->tcpstate
== server_ok
);
399 for (i
=0; i
<ads
->nudp
; i
++) {
400 udp
= &ads
->udpsocket
[i
];
403 udpaddrlen
= sizeof(udpaddr
);
404 r
= recvfrom(fd
,udpbuf
,sizeof(udpbuf
),0, &udpaddr
.sa
,&udpaddrlen
);
406 if (errno
== EAGAIN
|| errno
== EWOULDBLOCK
) { r
= 0; goto xit
; }
407 if (errno
== EINTR
) continue;
408 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
409 adns__warn(ads
,-1,0,"datagram receive error: %s",strerror(errno
));
413 serv
< ads
->nservers
&&
414 !adns__sockaddr_equal_p(&udpaddr
.sa
,
415 &ads
->servers
[serv
].addr
.sa
);
417 if (serv
>= ads
->nservers
) {
418 adns__warn(ads
,-1,0,"datagram received from unknown nameserver %s",
419 adns__sockaddr_ntoa(&udpaddr
.sa
, addrbuf
));
422 adns__procdgram(ads
,udpbuf
,r
,serv
,0,*now
);
429 adns__returning(ads
,0);
433 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
) {
436 adns__consistency(ads
,0,cc_entex
);
438 switch (ads
->tcpstate
) {
439 case server_disconnected
:
442 case server_connecting
:
443 if (fd
!= ads
->tcpsocket
) break;
444 assert(ads
->tcprecv
.used
==0);
445 assert(ads
->tcprecv_skip
==0);
447 if (!adns__vbuf_ensure(&ads
->tcprecv
,1)) { r
= ENOMEM
; goto xit
; }
448 r
= read(ads
->tcpsocket
,&ads
->tcprecv
.buf
,1);
449 if (r
==0 || (r
<0 && (errno
==EAGAIN
|| errno
==EWOULDBLOCK
))) {
450 tcp_connected(ads
,*now
);
454 adns__tcp_broken(ads
,"connect/read","sent data before first request");
457 if (errno
==EINTR
) continue;
458 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
459 adns__tcp_broken(ads
,"connect/read",strerror(errno
));
463 if (fd
!= ads
->tcpsocket
) break;
464 while (ads
->tcpsend
.used
) {
465 adns__sigpipe_protect(ads
);
466 r
= write(ads
->tcpsocket
,ads
->tcpsend
.buf
,ads
->tcpsend
.used
);
467 adns__sigpipe_unprotect(ads
);
469 if (errno
==EINTR
) continue;
470 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
471 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
472 adns__tcp_broken(ads
,"write",strerror(errno
));
475 ads
->tcpsend
.used
-= r
;
476 memmove(ads
->tcpsend
.buf
,ads
->tcpsend
.buf
+r
,ads
->tcpsend
.used
);
486 adns__returning(ads
,0);
490 int adns_processexceptional(adns_state ads
, int fd
,
491 const struct timeval
*now
) {
492 adns__consistency(ads
,0,cc_entex
);
493 switch (ads
->tcpstate
) {
494 case server_disconnected
:
497 case server_connecting
:
499 if (fd
!= ads
->tcpsocket
) break;
500 adns__tcp_broken(ads
,"poll/select","exceptional condition detected");
505 adns__returning(ads
,0);
509 static void fd_event(adns_state ads
, int fd
,
510 int revent
, int pollflag
,
511 int maxfd
, const fd_set
*fds
,
512 int (*func
)(adns_state
, int fd
,
513 const struct timeval
*now
),
514 struct timeval now
, int *r_r
) {
517 if (!(revent
& pollflag
)) return;
518 if (fds
&& !(fd
<maxfd
&& FD_ISSET(fd
,fds
))) return;
519 r
= func(ads
,fd
,&now
);
524 adns__diag(ads
,-1,0,"process fd failed after select:"
525 " %s",strerror(errno
));
526 adns_globalsystemfailure(ads
);
531 void adns__fdevents(adns_state ads
,
532 const struct pollfd
*pollfds
, int npollfds
,
533 int maxfd
, const fd_set
*readfds
,
534 const fd_set
*writefds
, const fd_set
*exceptfds
,
535 struct timeval now
, int *r_r
) {
538 for (i
=0; i
<npollfds
; i
++) {
540 if (fd
>= maxfd
) maxfd
= fd
+1;
541 revents
= pollfds
[i
].revents
;
542 #define EV(pollfl,fds,how) \
543 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
544 EV( POLLIN
, readfds
, readable
);
545 EV( POLLOUT
, writefds
, writeable
);
546 EV( POLLPRI
, exceptfds
, exceptional
);
551 /* Wrappers for select(2). */
553 void adns_beforeselect(adns_state ads
, int *maxfd_io
, fd_set
*readfds_io
,
554 fd_set
*writefds_io
, fd_set
*exceptfds_io
,
555 struct timeval
**tv_mod
, struct timeval
*tv_tobuf
,
556 const struct timeval
*now
) {
557 struct timeval tv_nowbuf
;
558 struct pollfd pollfds
[MAX_POLLFDS
];
559 int i
, fd
, maxfd
, npollfds
;
561 adns__consistency(ads
,0,cc_entex
);
563 if (tv_mod
&& (!*tv_mod
|| (*tv_mod
)->tv_sec
|| (*tv_mod
)->tv_usec
)) {
564 /* The caller is planning to sleep. */
565 adns__must_gettimeofday(ads
,&now
,&tv_nowbuf
);
566 if (!now
) { inter_immed(tv_mod
,tv_tobuf
); goto xit
; }
567 adns__timeouts(ads
, 0, tv_mod
,tv_tobuf
, *now
);
570 npollfds
= adns__pollfds(ads
,pollfds
);
572 for (i
=0; i
<npollfds
; i
++) {
574 if (fd
>= maxfd
) maxfd
= fd
+1;
575 if (pollfds
[i
].events
& POLLIN
) FD_SET(fd
,readfds_io
);
576 if (pollfds
[i
].events
& POLLOUT
) FD_SET(fd
,writefds_io
);
577 if (pollfds
[i
].events
& POLLPRI
) FD_SET(fd
,exceptfds_io
);
582 adns__returning(ads
,0);
585 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
586 const fd_set
*writefds
, const fd_set
*exceptfds
,
587 const struct timeval
*now
) {
588 struct timeval tv_buf
;
589 struct pollfd pollfds
[MAX_POLLFDS
];
592 adns__consistency(ads
,0,cc_entex
);
593 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
595 adns_processtimeouts(ads
,now
);
597 npollfds
= adns__pollfds(ads
,pollfds
);
598 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= POLLIN
|POLLOUT
|POLLPRI
;
601 maxfd
,readfds
,writefds
,exceptfds
,
604 adns__returning(ads
,0);
607 /* General helpful functions. */
609 void adns_globalsystemfailure(adns_state ads
) {
610 adns__consistency(ads
,0,cc_entex
);
612 while (ads
->udpw
.head
) adns__query_fail(ads
->udpw
.head
, adns_s_systemfail
);
613 while (ads
->tcpw
.head
) adns__query_fail(ads
->tcpw
.head
, adns_s_systemfail
);
615 switch (ads
->tcpstate
) {
616 case server_connecting
:
618 adns__tcp_broken(ads
,0,0);
620 case server_disconnected
:
626 adns__returning(ads
,0);
629 int adns_processany(adns_state ads
) {
632 struct pollfd pollfds
[MAX_POLLFDS
];
635 adns__consistency(ads
,0,cc_entex
);
637 r
= gettimeofday(&now
,0);
638 if (!r
) adns_processtimeouts(ads
,&now
);
640 /* We just use adns__fdevents to loop over the fd's trying them.
641 * This seems more sensible than calling select, since we're most
642 * likely just to want to do a read on one or two fds anyway.
644 npollfds
= adns__pollfds(ads
,pollfds
);
645 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= pollfds
[i
].events
& ~POLLPRI
;
651 adns__returning(ads
,0);
655 void adns__autosys(adns_state ads
, struct timeval now
) {
656 if (ads
->iflags
& adns_if_noautosys
) return;
657 adns_processany(ads
);
660 int adns__internal_check(adns_state ads
,
661 adns_query
*query_io
,
662 adns_answer
**answer
,
668 if (ads
->output
.head
) {
669 qu
= ads
->output
.head
;
670 } else if (ads
->udpw
.head
|| ads
->tcpw
.head
) {
676 if (qu
->id
>=0) return EAGAIN
;
678 LIST_UNLINK(ads
->output
,qu
);
680 if (context_r
) *context_r
= qu
->ctx
.ext
;
686 int adns_wait(adns_state ads
,
687 adns_query
*query_io
,
688 adns_answer
**answer_r
,
691 fd_set readfds
, writefds
, exceptfds
;
692 struct timeval tvbuf
, *tvp
;
694 adns__consistency(ads
,*query_io
,cc_entex
);
696 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
697 if (r
!= EAGAIN
) break;
699 FD_ZERO(&readfds
); FD_ZERO(&writefds
); FD_ZERO(&exceptfds
);
700 adns_beforeselect(ads
,&maxfd
,&readfds
,&writefds
,&exceptfds
,&tvp
,&tvbuf
,0);
702 rsel
= select(maxfd
,&readfds
,&writefds
,&exceptfds
,tvp
);
704 if (errno
== EINTR
) {
705 if (ads
->iflags
& adns_if_eintr
) { r
= EINTR
; break; }
707 adns__diag(ads
,-1,0,"select failed in wait: %s",strerror(errno
));
708 adns_globalsystemfailure(ads
);
712 adns_afterselect(ads
,maxfd
,&readfds
,&writefds
,&exceptfds
,0);
715 adns__returning(ads
,0);
719 int adns_check(adns_state ads
,
720 adns_query
*query_io
,
721 adns_answer
**answer_r
,
726 adns__consistency(ads
,*query_io
,cc_entex
);
727 r
= gettimeofday(&now
,0);
728 if (!r
) adns__autosys(ads
,now
);
730 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
731 adns__returning(ads
,0);