4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
9 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
11 * It is part of adns, which is
12 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
13 * Copyright (C) 1999 Tony Finch <dot@dotat.at>
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software Foundation,
27 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
34 #include <sys/types.h>
37 #include <sys/socket.h>
38 #include <netinet/in.h>
39 #include <arpa/inet.h>
43 /* TCP connection management. */
45 static void tcp_close(adns_state ads
) {
49 close(ads
->tcpsocket
);
51 ads
->tcprecv
.used
= ads
->tcprecv_skip
= ads
->tcpsend
.used
= 0;
54 void adns__tcp_broken(adns_state ads
, const char *what
, const char *why
) {
57 assert(ads
->tcpstate
== server_connecting
|| ads
->tcpstate
== server_ok
);
59 if (what
) adns__warn(ads
,serv
,0,"TCP connection failed: %s: %s",what
,why
);
62 ads
->tcpstate
= server_broken
;
63 ads
->tcpserver
= (serv
+1)%ads
->nservers
;
66 static void tcp_connected(adns_state ads
, struct timeval now
) {
69 adns__debug(ads
,ads
->tcpserver
,0,"TCP connected");
70 ads
->tcpstate
= server_ok
;
71 for (qu
= ads
->tcpw
.head
; qu
&& ads
->tcpstate
== server_ok
; qu
= nqu
) {
73 assert(qu
->state
== query_tcpw
);
74 adns__querysend_tcp(qu
,now
);
78 void adns__tcp_tryconnect(adns_state ads
, struct timeval now
) {
80 struct sockaddr_in addr
;
81 struct protoent
*proto
;
83 for (tries
=0; tries
<ads
->nservers
; tries
++) {
84 switch (ads
->tcpstate
) {
85 case server_connecting
:
89 case server_disconnected
:
95 assert(!ads
->tcpsend
.used
);
96 assert(!ads
->tcprecv
.used
);
97 assert(!ads
->tcprecv_skip
);
99 proto
= getprotobyname("tcp");
100 if (!proto
) { adns__diag(ads
,-1,0,"unable to find protocol no. for TCP !"); return; }
101 fd
= socket(AF_INET
,SOCK_STREAM
,proto
->p_proto
);
103 adns__diag(ads
,-1,0,"cannot create TCP socket: %s",strerror(errno
));
106 r
= adns__setnonblock(ads
,fd
);
108 adns__diag(ads
,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r
));
112 memset(&addr
,0,sizeof(addr
));
113 addr
.sin_family
= AF_INET
;
114 addr
.sin_port
= htons(DNS_PORT
);
115 addr
.sin_addr
= ads
->servers
[ads
->tcpserver
].addr
;
116 r
= connect(fd
,(const struct sockaddr
*)&addr
,sizeof(addr
));
118 ads
->tcpstate
= server_connecting
;
119 if (r
==0) { tcp_connected(ads
,now
); return; }
120 if (errno
== EWOULDBLOCK
|| errno
== EINPROGRESS
) {
121 ads
->tcptimeout
= now
;
122 timevaladd(&ads
->tcptimeout
,TCPCONNMS
);
125 adns__tcp_broken(ads
,"connect",strerror(errno
));
126 ads
->tcpstate
= server_disconnected
;
130 /* Timeout handling functions. */
132 void adns__must_gettimeofday(adns_state ads
, const struct timeval
**now_io
,
133 struct timeval
*tv_buf
) {
134 const struct timeval
*now
;
139 r
= gettimeofday(tv_buf
,0); if (!r
) { *now_io
= tv_buf
; return; }
140 adns__diag(ads
,-1,0,"gettimeofday failed: %s",strerror(errno
));
141 adns_globalsystemfailure(ads
);
145 static void inter_maxto(struct timeval
**tv_io
, struct timeval
*tvbuf
,
146 struct timeval maxto
) {
147 struct timeval
*rbuf
;
152 *tvbuf
= maxto
; *tv_io
= tvbuf
;
154 if (timercmp(rbuf
,&maxto
,>)) *rbuf
= maxto
;
156 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
157 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
160 static void inter_maxtoabs(struct timeval
**tv_io
, struct timeval
*tvbuf
,
161 struct timeval now
, struct timeval maxtime
) {
165 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
166 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
168 maxtime
.tv_sec
-= (now
.tv_sec
+2);
169 maxtime
.tv_usec
-= (now
.tv_usec
-2000000);
170 dr
= ldiv(maxtime
.tv_usec
,1000000);
171 maxtime
.tv_sec
+= dr
.quot
;
172 maxtime
.tv_usec
-= dr
.quot
*1000000;
173 if (maxtime
.tv_sec
<0) timerclear(&maxtime
);
174 inter_maxto(tv_io
,tvbuf
,maxtime
);
177 static void timeouts_queue(adns_state ads
, int act
,
178 struct timeval
**tv_io
, struct timeval
*tvbuf
,
179 struct timeval now
, struct query_queue
*queue
) {
182 for (qu
= queue
->head
; qu
; qu
= nqu
) {
184 if (!timercmp(&now
,&qu
->timeout
,>)) {
185 inter_maxtoabs(tv_io
,tvbuf
,now
,qu
->timeout
);
193 LIST_UNLINK(*queue
,qu
);
194 if (qu
->state
!= query_tosend
) {
195 adns__query_fail(qu
,adns_s_timeout
);
197 adns__query_send(qu
,now
);
204 static void tcp_events(adns_state ads
, int act
,
205 struct timeval
**tv_io
, struct timeval
*tvbuf
,
206 struct timeval now
) {
210 switch (ads
->tcpstate
) {
212 for (qu
= ads
->tcpw
.head
; qu
; qu
= nqu
) {
214 assert(qu
->state
== query_tcpw
);
215 if (qu
->retries
> ads
->nservers
) {
216 LIST_UNLINK(ads
->tcpw
,qu
);
217 adns__query_fail(qu
,adns_s_allservfail
);
220 ads
->tcpstate
= server_disconnected
;
221 case server_disconnected
: /* fall through */
222 if (!ads
->tcpw
.head
) return;
223 adns__tcp_tryconnect(ads
,now
);
226 if (ads
->tcpw
.head
) return;
227 if (!ads
->tcptimeout
.tv_sec
) {
228 assert(!ads
->tcptimeout
.tv_usec
);
229 ads
->tcptimeout
= now
;
230 timevaladd(&ads
->tcptimeout
,TCPIDLEMS
);
232 case server_connecting
: /* fall through */
233 if (!timercmp(&now
,&ads
->tcptimeout
,>)) {
234 inter_maxtoabs(tv_io
,tvbuf
,now
,ads
->tcptimeout
);
237 /* TCP timeout has happened */
238 switch (ads
->tcpstate
) {
239 case server_connecting
: /* failed to connect */
240 adns__tcp_broken(ads
,"unable to make connection","timed out");
242 case server_ok
: /* idle timeout */
244 ads
->tcpstate
= server_disconnected
;
257 void adns__timeouts(adns_state ads
, int act
,
258 struct timeval
**tv_io
, struct timeval
*tvbuf
,
259 struct timeval now
) {
260 timeouts_queue(ads
,act
,tv_io
,tvbuf
,now
, &ads
->udpw
);
261 timeouts_queue(ads
,act
,tv_io
,tvbuf
,now
, &ads
->tcpw
);
262 tcp_events(ads
,act
,tv_io
,tvbuf
,now
);
265 void adns_firsttimeout(adns_state ads
,
266 struct timeval
**tv_io
, struct timeval
*tvbuf
,
267 struct timeval now
) {
268 adns__consistency(ads
,0,cc_entex
);
269 adns__timeouts(ads
, 0, tv_io
,tvbuf
, now
);
270 adns__consistency(ads
,0,cc_entex
);
273 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
) {
274 struct timeval tv_buf
;
276 adns__consistency(ads
,0,cc_entex
);
277 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
278 if (now
) adns__timeouts(ads
, 1, 0,0, *now
);
279 adns__consistency(ads
,0,cc_entex
);
282 /* fd handling functions. These are the top-level of the real work of
283 * reception and often transmission.
286 int adns__pollfds(adns_state ads
, struct pollfd pollfds_buf
[MAX_POLLFDS
]) {
287 /* Returns the number of entries filled in. Always zeroes revents. */
289 assert(MAX_POLLFDS
==2);
291 pollfds_buf
[0].fd
= ads
->udpsocket
;
292 pollfds_buf
[0].events
= POLLIN
;
293 pollfds_buf
[0].revents
= 0;
295 switch (ads
->tcpstate
) {
296 case server_disconnected
:
298 case server_connecting
:
299 pollfds_buf
[1].events
= POLLOUT
;
302 pollfds_buf
[1].events
= ads
->tcpsend
.used ? POLLIN
|POLLOUT
|POLLPRI
: POLLIN
|POLLPRI
;
307 pollfds_buf
[1].fd
= ads
->tcpsocket
;
311 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
) {
312 int want
, dgramlen
, r
, udpaddrlen
, serv
, old_skip
;
313 byte udpbuf
[DNS_MAXUDP
];
314 struct sockaddr_in udpaddr
;
316 adns__consistency(ads
,0,cc_entex
);
318 switch (ads
->tcpstate
) {
319 case server_disconnected
:
320 case server_connecting
:
323 if (fd
!= ads
->tcpsocket
) break;
324 assert(!ads
->tcprecv_skip
);
326 if (ads
->tcprecv
.used
>= ads
->tcprecv_skip
+2) {
327 dgramlen
= ((ads
->tcprecv
.buf
[ads
->tcprecv_skip
]<<8) |
328 ads
->tcprecv
.buf
[ads
->tcprecv_skip
+1]);
329 if (ads
->tcprecv
.used
>= ads
->tcprecv_skip
+2+dgramlen
) {
330 old_skip
= ads
->tcprecv_skip
;
331 ads
->tcprecv_skip
+= 2+dgramlen
;
332 adns__procdgram(ads
, ads
->tcprecv
.buf
+old_skip
+2,
333 dgramlen
, ads
->tcpserver
, 1,*now
);
341 ads
->tcprecv
.used
-= ads
->tcprecv_skip
;
342 memmove(ads
->tcprecv
.buf
,ads
->tcprecv
.buf
+ads
->tcprecv_skip
,ads
->tcprecv
.used
);
343 ads
->tcprecv_skip
= 0;
344 if (!adns__vbuf_ensure(&ads
->tcprecv
,want
)) { r
= ENOMEM
; goto xit
; }
345 assert(ads
->tcprecv
.used
<= ads
->tcprecv
.avail
);
346 if (ads
->tcprecv
.used
== ads
->tcprecv
.avail
) continue;
347 r
= read(ads
->tcpsocket
,
348 ads
->tcprecv
.buf
+ads
->tcprecv
.used
,
349 ads
->tcprecv
.avail
-ads
->tcprecv
.used
);
351 ads
->tcprecv
.used
+= r
;
354 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
355 if (errno
==EINTR
) continue;
356 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
358 adns__tcp_broken(ads
,"read",r?
strerror(errno
):"closed");
361 } /* never reached */
365 if (fd
== ads
->udpsocket
) {
367 udpaddrlen
= sizeof(udpaddr
);
368 r
= recvfrom(ads
->udpsocket
,udpbuf
,sizeof(udpbuf
),0,
369 (struct sockaddr
*)&udpaddr
,&udpaddrlen
);
371 if (errno
== EAGAIN
|| errno
== EWOULDBLOCK
) { r
= 0; goto xit
; }
372 if (errno
== EINTR
) continue;
373 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
374 adns__warn(ads
,-1,0,"datagram receive error: %s",strerror(errno
));
377 if (udpaddrlen
!= sizeof(udpaddr
)) {
378 adns__diag(ads
,-1,0,"datagram received with wrong address length %d"
379 " (expected %d)", udpaddrlen
,sizeof(udpaddr
));
382 if (udpaddr
.sin_family
!= AF_INET
) {
383 adns__diag(ads
,-1,0,"datagram received with wrong protocol family"
384 " %u (expected %u)",udpaddr
.sin_family
,AF_INET
);
387 if (ntohs(udpaddr
.sin_port
) != DNS_PORT
) {
388 adns__diag(ads
,-1,0,"datagram received from wrong port %u (expected %u)",
389 ntohs(udpaddr
.sin_port
),DNS_PORT
);
393 serv
< ads
->nservers
&&
394 ads
->servers
[serv
].addr
.s_addr
!= udpaddr
.sin_addr
.s_addr
;
396 if (serv
>= ads
->nservers
) {
397 adns__warn(ads
,-1,0,"datagram received from unknown nameserver %s",
398 inet_ntoa(udpaddr
.sin_addr
));
401 adns__procdgram(ads
,udpbuf
,r
,serv
,0,*now
);
406 adns__consistency(ads
,0,cc_entex
);
410 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
) {
413 adns__consistency(ads
,0,cc_entex
);
415 switch (ads
->tcpstate
) {
416 case server_disconnected
:
418 case server_connecting
:
419 if (fd
!= ads
->tcpsocket
) break;
420 assert(ads
->tcprecv
.used
==0);
421 assert(ads
->tcprecv_skip
==0);
423 if (!adns__vbuf_ensure(&ads
->tcprecv
,1)) { r
= ENOMEM
; goto xit
; }
424 r
= read(ads
->tcpsocket
,&ads
->tcprecv
.buf
,1);
425 if (r
==0 || (r
<0 && (errno
==EAGAIN
|| errno
==EWOULDBLOCK
))) {
426 tcp_connected(ads
,*now
);
430 adns__tcp_broken(ads
,"connect/read","sent data before first request");
433 if (errno
==EINTR
) continue;
434 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
435 adns__tcp_broken(ads
,"connect/read",strerror(errno
));
439 if (!(ads
->tcpsend
.used
&& fd
== ads
->tcpsocket
)) break;
441 adns__sigpipe_protect(ads
);
442 r
= write(ads
->tcpsocket
,ads
->tcpsend
.buf
,ads
->tcpsend
.used
);
443 adns__sigpipe_unprotect(ads
);
445 if (errno
==EINTR
) continue;
446 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) { r
= 0; goto xit
; }
447 if (errno_resources(errno
)) { r
= errno
; goto xit
; }
448 adns__tcp_broken(ads
,"write",strerror(errno
));
451 ads
->tcpsend
.used
-= r
;
452 memmove(ads
->tcpsend
.buf
,ads
->tcpsend
.buf
+r
,ads
->tcpsend
.used
);
460 adns__consistency(ads
,0,cc_entex
);
464 int adns_processexceptional(adns_state ads
, int fd
, const struct timeval
*now
) {
465 adns__consistency(ads
,0,cc_entex
);
466 switch (ads
->tcpstate
) {
467 case server_disconnected
:
469 case server_connecting
:
471 if (fd
!= ads
->tcpsocket
) break;
472 adns__tcp_broken(ads
,"poll/select","exceptional condition detected");
477 adns__consistency(ads
,0,cc_entex
);
481 static void fd_event(adns_state ads
, int fd
,
482 int revent
, int pollflag
,
483 int maxfd
, const fd_set
*fds
,
484 int (*func
)(adns_state
, int fd
, const struct timeval
*now
),
485 struct timeval now
, int *r_r
) {
488 if (!(revent
& pollflag
)) return;
489 if (fds
&& !(fd
<maxfd
&& FD_ISSET(fd
,fds
))) return;
490 r
= func(ads
,fd
,&now
);
495 adns__diag(ads
,-1,0,"process fd failed after select: %s",strerror(errno
));
496 adns_globalsystemfailure(ads
);
501 void adns__fdevents(adns_state ads
,
502 const struct pollfd
*pollfds
, int npollfds
,
503 int maxfd
, const fd_set
*readfds
,
504 const fd_set
*writefds
, const fd_set
*exceptfds
,
505 struct timeval now
, int *r_r
) {
508 for (i
=0; i
<npollfds
; i
++) {
510 if (fd
>= maxfd
) maxfd
= fd
+1;
511 revents
= pollfds
[i
].revents
;
512 fd_event(ads
,fd
, revents
,POLLIN
, maxfd
,readfds
, adns_processreadable
,now
,r_r
);
513 fd_event(ads
,fd
, revents
,POLLOUT
, maxfd
,writefds
, adns_processwriteable
,now
,r_r
);
514 fd_event(ads
,fd
, revents
,POLLPRI
, maxfd
,exceptfds
, adns_processexceptional
,now
,r_r
);
518 /* Wrappers for select(2). */
520 void adns_beforeselect(adns_state ads
, int *maxfd_io
, fd_set
*readfds_io
,
521 fd_set
*writefds_io
, fd_set
*exceptfds_io
,
522 struct timeval
**tv_mod
, struct timeval
*tv_tobuf
,
523 const struct timeval
*now
) {
524 struct timeval tv_nowbuf
;
525 struct pollfd pollfds
[MAX_POLLFDS
];
526 int i
, fd
, maxfd
, npollfds
;
528 adns__consistency(ads
,0,cc_entex
);
530 if (tv_mod
&& (!*tv_mod
|| (*tv_mod
)->tv_sec
|| (*tv_mod
)->tv_usec
)) {
531 /* The caller is planning to sleep. */
532 adns__must_gettimeofday(ads
,&now
,&tv_nowbuf
);
534 adns__timeouts(ads
, 1, tv_mod
,tv_tobuf
, *now
);
537 npollfds
= adns__pollfds(ads
,pollfds
);
539 for (i
=0; i
<npollfds
; i
++) {
541 if (fd
>= maxfd
) maxfd
= fd
+1;
542 if (pollfds
[i
].events
& POLLIN
) FD_SET(fd
,readfds_io
);
543 if (pollfds
[i
].events
& POLLOUT
) FD_SET(fd
,writefds_io
);
544 if (pollfds
[i
].events
& POLLPRI
) FD_SET(fd
,exceptfds_io
);
549 adns__consistency(ads
,0,cc_entex
);
552 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
553 const fd_set
*writefds
, const fd_set
*exceptfds
,
554 const struct timeval
*now
) {
555 struct timeval tv_buf
;
556 struct pollfd pollfds
[MAX_POLLFDS
];
559 adns__consistency(ads
,0,cc_entex
);
560 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
562 adns_processtimeouts(ads
,now
);
564 npollfds
= adns__pollfds(ads
,pollfds
);
565 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= POLLIN
|POLLOUT
|POLLPRI
;
568 maxfd
,readfds
,writefds
,exceptfds
,
571 adns__consistency(ads
,0,cc_entex
);
574 /* General helpful functions. */
576 void adns_globalsystemfailure(adns_state ads
) {
577 adns__consistency(ads
,0,cc_entex
);
579 while (ads
->udpw
.head
) adns__query_fail(ads
->udpw
.head
, adns_s_systemfail
);
580 while (ads
->tcpw
.head
) adns__query_fail(ads
->tcpw
.head
, adns_s_systemfail
);
582 switch (ads
->tcpstate
) {
583 case server_connecting
:
585 adns__tcp_broken(ads
,0,0);
587 case server_disconnected
:
592 adns__consistency(ads
,0,cc_entex
);
595 int adns_processany(adns_state ads
) {
598 struct pollfd pollfds
[MAX_POLLFDS
];
601 adns__consistency(ads
,0,cc_entex
);
603 r
= gettimeofday(&now
,0);
604 if (!r
) adns_processtimeouts(ads
,&now
);
606 /* We just use adns__fdevents to loop over the fd's trying them.
607 * This seems more sensible than calling select, since we're most
608 * likely just to want to do a read on one or two fds anyway.
610 npollfds
= adns__pollfds(ads
,pollfds
);
611 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= pollfds
[i
].events
;
617 adns__consistency(ads
,0,cc_entex
);
621 void adns__autosys(adns_state ads
, struct timeval now
) {
622 if (ads
->iflags
& adns_if_noautosys
) return;
623 adns_processany(ads
);
626 int adns__internal_check(adns_state ads
,
627 adns_query
*query_io
,
628 adns_answer
**answer
,
634 if (ads
->output
.head
) {
635 qu
= ads
->output
.head
;
636 } else if (ads
->udpw
.head
|| ads
->tcpw
.head
) {
642 if (qu
->id
>=0) return EAGAIN
;
644 LIST_UNLINK(ads
->output
,qu
);
646 if (context_r
) *context_r
= qu
->ctx
.ext
;
652 int adns_wait(adns_state ads
,
653 adns_query
*query_io
,
654 adns_answer
**answer_r
,
657 fd_set readfds
, writefds
, exceptfds
;
658 struct timeval tvbuf
, *tvp
;
660 adns__consistency(ads
,*query_io
,cc_entex
);
662 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
663 if (r
!= EAGAIN
) break;
665 FD_ZERO(&readfds
); FD_ZERO(&writefds
); FD_ZERO(&exceptfds
);
666 adns_beforeselect(ads
,&maxfd
,&readfds
,&writefds
,&exceptfds
,&tvp
,&tvbuf
,0);
667 rsel
= select(maxfd
,&readfds
,&writefds
,&exceptfds
,tvp
);
669 if (errno
== EINTR
) {
670 if (ads
->iflags
& adns_if_eintr
) { r
= EINTR
; break; }
672 adns__diag(ads
,-1,0,"select failed in wait: %s",strerror(errno
));
673 adns_globalsystemfailure(ads
);
677 adns_afterselect(ads
,maxfd
,&readfds
,&writefds
,&exceptfds
,0);
680 adns__consistency(ads
,0,cc_entex
);
684 int adns_check(adns_state ads
,
685 adns_query
*query_io
,
686 adns_answer
**answer_r
,
691 adns__consistency(ads
,*query_io
,cc_entex
);
692 r
= gettimeofday(&now
,0);
693 if (!r
) adns__autosys(ads
,now
);
695 r
= adns__internal_check(ads
,query_io
,answer_r
,context_r
);
696 adns__consistency(ads
,0,cc_entex
);