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 <sys/types.h>
33 #include <sys/socket.h>
34 #include <netinet/in.h>
35 #include <arpa/inet.h>
39 /* TCP connection management. */
41 void adns__tcp_closenext(adns_state ads
) {
45 close(ads
->tcpsocket
);
46 ads
->tcpstate
= server_disconnected
;
47 ads
->tcprecv
.used
= ads
->tcpsend
.used
= 0;
48 ads
->tcpserver
= (serv
+1)%ads
->nservers
;
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 adns__warn(ads
,serv
,0,"TCP connection lost: %s: %s",what
,why
);
58 adns__tcp_closenext(ads
);
60 for (qu
= ads
->timew
.head
; qu
; qu
= nqu
) {
62 if (qu
->state
== query_udp
) continue;
63 assert(qu
->state
== query_tcpwait
|| qu
->state
== query_tcpsent
);
64 qu
->state
= query_tcpwait
;
65 qu
->tcpfailed
|= (1<<serv
);
66 if (qu
->tcpfailed
== (1<<ads
->nservers
)-1) {
67 LIST_UNLINK(ads
->timew
,qu
);
68 adns__query_fail(qu
,adns_s_allservfail
);
73 static void tcp_connected(adns_state ads
, struct timeval now
) {
76 adns__debug(ads
,ads
->tcpserver
,0,"TCP connected");
77 ads
->tcpstate
= server_ok
;
78 for (qu
= ads
->timew
.head
; qu
; qu
= nqu
) {
80 if (qu
->state
== query_udp
) continue;
81 assert (qu
->state
== query_tcpwait
);
82 adns__query_tcp(qu
,now
);
86 void adns__tcp_tryconnect(adns_state ads
, struct timeval now
) {
88 struct sockaddr_in addr
;
89 struct protoent
*proto
;
91 for (tries
=0; tries
<ads
->nservers
; tries
++) {
92 if (ads
->tcpstate
== server_connecting
|| ads
->tcpstate
== server_ok
) return;
93 assert(ads
->tcpstate
== server_disconnected
);
94 assert(!ads
->tcpsend
.used
);
95 assert(!ads
->tcprecv
.used
);
97 proto
= getprotobyname("tcp");
98 if (!proto
) { adns__diag(ads
,-1,0,"unable to find protocol no. for TCP !"); return; }
99 fd
= socket(AF_INET
,SOCK_STREAM
,proto
->p_proto
);
101 adns__diag(ads
,-1,0,"cannot create TCP socket: %s",strerror(errno
));
104 r
= adns__setnonblock(ads
,fd
);
106 adns__diag(ads
,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r
));
110 memset(&addr
,0,sizeof(addr
));
111 addr
.sin_family
= AF_INET
;
112 addr
.sin_port
= htons(DNS_PORT
);
113 addr
.sin_addr
= ads
->servers
[ads
->tcpserver
].addr
;
114 r
= connect(fd
,(const struct sockaddr
*)&addr
,sizeof(addr
));
116 ads
->tcpstate
= server_connecting
;
117 if (r
==0) { tcp_connected(ads
,now
); continue; }
118 if (errno
== EWOULDBLOCK
|| errno
== EINPROGRESS
) return;
119 adns__tcp_broken(ads
,"connect",strerror(errno
));
123 /* Timeout handling functions. */
125 void adns__must_gettimeofday(adns_state ads
, const struct timeval
**now_io
,
126 struct timeval
*tv_buf
) {
127 const struct timeval
*now
;
132 r
= gettimeofday(tv_buf
,0); if (!r
) { *now_io
= tv_buf
; return; }
133 adns__diag(ads
,-1,0,"gettimeofday failed: %s",strerror(errno
));
134 adns_globalsystemfailure(ads
);
138 static void inter_maxto(struct timeval
**tv_io
, struct timeval
*tvbuf
,
139 struct timeval maxto
) {
140 struct timeval
*rbuf
;
145 *tvbuf
= maxto
; *tv_io
= tvbuf
;
147 if (timercmp(rbuf
,&maxto
,>)) *rbuf
= maxto
;
149 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
150 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
153 static void inter_maxtoabs(struct timeval
**tv_io
, struct timeval
*tvbuf
,
154 struct timeval now
, struct timeval maxtime
) {
157 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
158 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
160 maxtime
.tv_sec
-= (now
.tv_sec
+2);
161 maxtime
.tv_usec
-= (now
.tv_usec
-2000000);
162 dr
= ldiv(maxtime
.tv_usec
,1000000);
163 maxtime
.tv_sec
+= dr
.quot
;
164 maxtime
.tv_usec
-= dr
.quot
*1000000;
165 if (maxtime
.tv_sec
<0) timerclear(&maxtime
);
166 inter_maxto(tv_io
,tvbuf
,maxtime
);
169 void adns__timeouts(adns_state ads
, int act
,
170 struct timeval
**tv_io
, struct timeval
*tvbuf
,
171 struct timeval now
) {
174 for (qu
= ads
->timew
.head
; qu
; qu
= nqu
) {
176 if (timercmp(&now
,&qu
->timeout
,<=)) {
177 if (!tv_io
) continue;
178 inter_maxtoabs(tv_io
,tvbuf
,now
,qu
->timeout
);
181 LIST_UNLINK(ads
->timew
,qu
);
182 if (qu
->state
!= query_udp
) {
183 adns__query_fail(qu
,adns_s_timeout
);
185 adns__query_udp(qu
,now
);
187 nqu
= ads
->timew
.head
;
192 void adns_firsttimeout(adns_state ads
,
193 struct timeval
**tv_io
, struct timeval
*tvbuf
,
194 struct timeval now
) {
195 adns__timeouts(ads
, 0, tv_io
,tvbuf
, now
);
198 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
) {
199 struct timeval tv_buf
;
201 adns__must_gettimeofday(ads
,&now
,&tv_buf
); if (!now
) return;
202 adns__timeouts(ads
, 1, 0,0, *now
);
205 /* fd handling functions. These are the top-level of the real work of
206 * reception and often transmission.
209 int adns__pollfds(adns_state ads
, struct pollfd pollfds_buf
[MAX_POLLFDS
]) {
210 /* Returns the number of entries filled in. Always zeroes revents. */
212 assert(MAX_POLLFDS
==2);
214 pollfds_buf
[0].fd
= ads
->udpsocket
;
215 pollfds_buf
[0].events
= POLLIN
;
216 pollfds_buf
[0].revents
= 0;
218 switch (ads
->tcpstate
) {
219 case server_disconnected
:
221 case server_connecting
:
222 pollfds_buf
[1].events
= POLLOUT
;
225 pollfds_buf
[1].events
= ads
->tcpsend
.used ? POLLIN
|POLLOUT
|POLLPRI
: POLLIN
|POLLPRI
;
230 pollfds_buf
[1].fd
= ads
->tcpsocket
;
231 pollfds_buf
[1].revents
= 0;
235 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
) {
236 int skip
, want
, dgramlen
, r
, udpaddrlen
, serv
;
237 byte udpbuf
[DNS_MAXUDP
];
238 struct sockaddr_in udpaddr
;
240 switch (ads
->tcpstate
) {
241 case server_disconnected
:
242 case server_connecting
:
245 if (fd
!= ads
->tcpsocket
) break;
248 if (ads
->tcprecv
.used
<skip
+2) {
251 dgramlen
= (ads
->tcprecv
.buf
[skip
]<<8) | ads
->tcprecv
.buf
[skip
+1];
252 if (ads
->tcprecv
.used
<skip
+2+dgramlen
) {
255 adns__procdgram(ads
,ads
->tcprecv
.buf
+skip
+2,dgramlen
,ads
->tcpserver
,*now
);
256 skip
+= 2+dgramlen
; continue;
259 ads
->tcprecv
.used
-= skip
;
260 memmove(ads
->tcprecv
.buf
,ads
->tcprecv
.buf
+skip
,ads
->tcprecv
.used
);
262 if (!adns__vbuf_ensure(&ads
->tcprecv
,want
)) return ENOMEM
;
263 assert(ads
->tcprecv
.used
<= ads
->tcprecv
.avail
);
264 if (ads
->tcprecv
.used
== ads
->tcprecv
.avail
) continue;
265 r
= read(ads
->tcpsocket
,
266 ads
->tcprecv
.buf
+ads
->tcprecv
.used
,
267 ads
->tcprecv
.avail
-ads
->tcprecv
.used
);
269 ads
->tcprecv
.used
+= r
;
272 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) return 0;
273 if (errno
==EINTR
) continue;
274 if (errno_resources(errno
)) return errno
;
276 adns__tcp_broken(ads
,"read",r?
strerror(errno
):"closed");
279 } /* never reached */
283 if (fd
== ads
->udpsocket
) {
285 udpaddrlen
= sizeof(udpaddr
);
286 r
= recvfrom(ads
->udpsocket
,udpbuf
,sizeof(udpbuf
),0,
287 (struct sockaddr
*)&udpaddr
,&udpaddrlen
);
289 if (errno
== EAGAIN
|| errno
== EWOULDBLOCK
) return 0;
290 if (errno
== EINTR
) continue;
291 if (errno_resources(errno
)) return errno
;
292 adns__warn(ads
,-1,0,"datagram receive error: %s",strerror(errno
));
295 if (udpaddrlen
!= sizeof(udpaddr
)) {
296 adns__diag(ads
,-1,0,"datagram received with wrong address length %d"
297 " (expected %d)", udpaddrlen
,sizeof(udpaddr
));
300 if (udpaddr
.sin_family
!= AF_INET
) {
301 adns__diag(ads
,-1,0,"datagram received with wrong protocol family"
302 " %u (expected %u)",udpaddr
.sin_family
,AF_INET
);
305 if (ntohs(udpaddr
.sin_port
) != DNS_PORT
) {
306 adns__diag(ads
,-1,0,"datagram received from wrong port %u (expected %u)",
307 ntohs(udpaddr
.sin_port
),DNS_PORT
);
311 serv
< ads
->nservers
&&
312 ads
->servers
[serv
].addr
.s_addr
!= udpaddr
.sin_addr
.s_addr
;
314 if (serv
>= ads
->nservers
) {
315 adns__warn(ads
,-1,0,"datagram received from unknown nameserver %s",
316 inet_ntoa(udpaddr
.sin_addr
));
319 adns__procdgram(ads
,udpbuf
,r
,serv
,*now
);
325 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
) {
328 switch (ads
->tcpstate
) {
329 case server_disconnected
:
331 case server_connecting
:
332 if (fd
!= ads
->tcpsocket
) break;
333 assert(ads
->tcprecv
.used
==0);
335 if (!adns__vbuf_ensure(&ads
->tcprecv
,1)) return ENOMEM
;
336 r
= read(ads
->tcpsocket
,&ads
->tcprecv
.buf
,1);
337 if (r
==0 || (r
<0 && (errno
==EAGAIN
|| errno
==EWOULDBLOCK
))) {
338 tcp_connected(ads
,*now
);
342 adns__tcp_broken(ads
,"connect/read","sent data before first request");
345 if (errno
==EINTR
) continue;
346 if (errno_resources(errno
)) return errno
;
347 adns__tcp_broken(ads
,"connect/read",strerror(errno
));
351 if (!(ads
->tcpsend
.used
&& fd
== ads
->tcpsocket
)) break;
353 adns__sigpipe_protect(ads
);
354 r
= write(ads
->tcpsocket
,ads
->tcpsend
.buf
,ads
->tcpsend
.used
);
355 adns__sigpipe_unprotect(ads
);
357 if (errno
==EINTR
) continue;
358 if (errno
==EAGAIN
|| errno
==EWOULDBLOCK
) return 0;
359 if (errno_resources(errno
)) return errno
;
360 adns__tcp_broken(ads
,"write",strerror(errno
));
363 ads
->tcpsend
.used
-= r
;
364 memmove(ads
->tcpsend
.buf
,ads
->tcpsend
.buf
+r
,ads
->tcpsend
.used
);
373 int adns_processexceptional(adns_state ads
, int fd
, const struct timeval
*now
) {
374 switch (ads
->tcpstate
) {
375 case server_disconnected
:
377 case server_connecting
:
379 if (fd
!= ads
->tcpsocket
) break;
380 adns__tcp_broken(ads
,"poll/select","exceptional condition detected");
388 static void fd_event(adns_state ads
, int fd
,
389 int revent
, int pollflag
,
390 int maxfd
, const fd_set
*fds
,
391 int (*func
)(adns_state
, int fd
, const struct timeval
*now
),
392 struct timeval now
, int *r_r
) {
395 if (!(revent
& pollflag
)) return;
396 if (fds
&& !(fd
<maxfd
&& FD_ISSET(fd
,fds
))) return;
397 r
= func(ads
,fd
,&now
);
402 adns__diag(ads
,-1,0,"process fd failed after select: %s",strerror(errno
));
403 adns_globalsystemfailure(ads
);
408 void adns__fdevents(adns_state ads
,
409 const struct pollfd
*pollfds
, int npollfds
,
410 int maxfd
, const fd_set
*readfds
,
411 const fd_set
*writefds
, const fd_set
*exceptfds
,
412 struct timeval now
, int *r_r
) {
415 for (i
=0; i
<npollfds
; i
++) {
417 if (fd
>= maxfd
) maxfd
= fd
+1;
418 revents
= pollfds
[i
].revents
;
419 fd_event(ads
,fd
, revents
,POLLIN
, maxfd
,readfds
, adns_processreadable
,now
,r_r
);
420 fd_event(ads
,fd
, revents
,POLLOUT
, maxfd
,writefds
, adns_processwriteable
,now
,r_r
);
421 fd_event(ads
,fd
, revents
,POLLPRI
, maxfd
,exceptfds
, adns_processexceptional
,now
,r_r
);
425 /* Wrappers for select(2). */
427 void adns_beforeselect(adns_state ads
, int *maxfd_io
, fd_set
*readfds_io
,
428 fd_set
*writefds_io
, fd_set
*exceptfds_io
,
429 struct timeval
**tv_mod
, struct timeval
*tv_tobuf
,
430 const struct timeval
*now
) {
431 struct timeval tv_nowbuf
;
432 struct pollfd pollfds
[MAX_POLLFDS
];
433 int i
, fd
, maxfd
, npollfds
;
435 if (tv_mod
&& (!*tv_mod
|| (*tv_mod
)->tv_sec
|| (*tv_mod
)->tv_usec
)) {
436 /* The caller is planning to sleep. */
437 adns__must_gettimeofday(ads
,&now
,&tv_nowbuf
);
439 adns__timeouts(ads
, 1, tv_mod
,tv_tobuf
, *now
);
442 npollfds
= adns__pollfds(ads
,pollfds
);
444 for (i
=0; i
<npollfds
; i
++) {
446 if (fd
>= maxfd
) maxfd
= fd
+1;
447 if (pollfds
[i
].events
& POLLIN
) FD_SET(fd
,readfds_io
);
448 if (pollfds
[i
].events
& POLLOUT
) FD_SET(fd
,writefds_io
);
449 if (pollfds
[i
].events
& POLLPRI
) FD_SET(fd
,exceptfds_io
);
454 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
455 const fd_set
*writefds
, const fd_set
*exceptfds
,
456 const struct timeval
*now
) {
457 struct timeval tv_buf
;
458 struct pollfd pollfds
[MAX_POLLFDS
];
461 adns__must_gettimeofday(ads
,&now
,&tv_buf
);
463 adns_processtimeouts(ads
,now
);
465 npollfds
= adns__pollfds(ads
,pollfds
);
466 for (i
=0; i
<npollfds
; i
++) pollfds
[i
].revents
= POLLIN
|POLLOUT
|POLLPRI
;
469 maxfd
,readfds
,writefds
,exceptfds
,
473 /* General helpful functions. */
475 void adns_globalsystemfailure(adns_state ads
) {
476 while (ads
->timew
.head
) {
477 adns__query_fail(ads
->timew
.head
, adns_s_systemfail
);
480 switch (ads
->tcpstate
) {
481 case server_connecting
:
483 adns__tcp_closenext(ads
);
485 case server_disconnected
:
492 int adns_processany(adns_state ads
) {
495 struct pollfd pollfds
[MAX_POLLFDS
];
498 r
= gettimeofday(&now
,0);
499 if (!r
) adns_processtimeouts(ads
,&now
);
501 npollfds
= adns__pollfds(ads
,pollfds
);
509 void adns__autosys(adns_state ads
, struct timeval now
) {
510 if (ads
->iflags
& adns_if_noautosys
) return;
511 adns_processany(ads
);
514 static int internal_check(adns_state ads
,
515 adns_query
*query_io
,
516 adns_answer
**answer
,
522 if (!ads
->output
.head
) return EWOULDBLOCK
;
523 qu
= ads
->output
.head
;
525 if (qu
->id
>=0) return EWOULDBLOCK
;
527 LIST_UNLINK(ads
->output
,qu
);
529 if (context_r
) *context_r
= qu
->ctx
.ext
;
534 int adns_wait(adns_state ads
,
535 adns_query
*query_io
,
536 adns_answer
**answer_r
,
539 fd_set readfds
, writefds
, exceptfds
;
540 struct timeval tvbuf
, *tvp
;
543 r
= internal_check(ads
,query_io
,answer_r
,context_r
);
544 if (r
!= EWOULDBLOCK
) return r
;
546 FD_ZERO(&readfds
); FD_ZERO(&writefds
); FD_ZERO(&exceptfds
);
547 adns_beforeselect(ads
,&maxfd
,&readfds
,&writefds
,&exceptfds
,&tvp
,&tvbuf
,0);
548 rsel
= select(maxfd
,&readfds
,&writefds
,&exceptfds
,tvp
);
550 if (errno
== EINTR
) {
551 if (ads
->iflags
& adns_if_eintr
) return EINTR
;
553 adns__diag(ads
,-1,0,"select failed in wait: %s",strerror(errno
));
554 adns_globalsystemfailure(ads
);
558 adns_afterselect(ads
,maxfd
,&readfds
,&writefds
,&exceptfds
,0);
563 int adns_check(adns_state ads
,
564 adns_query
*query_io
,
565 adns_answer
**answer_r
,
570 r
= gettimeofday(&now
,0);
571 if (!r
) adns__autosys(ads
,now
);
573 return internal_check(ads
,query_io
,answer_r
,context_r
);