1 /*
2 * event.c
3 * - event loop core
4 * - TCP connection management
5 * - user-visible check/wait and event-loop-related functions
6 */
7 /*
8 * This file is part of adns, which is
9 * Copyright (C) 1997-2000,2003,2006,2014-2016,2020 Ian Jackson
10 * Copyright (C) 2014 Mark Wooding
11 * Copyright (C) 1999-2000,2003,2006 Tony Finch
12 * Copyright (C) 1991 Massachusetts Institute of Technology
13 * (See the file INSTALL for full details.)
14 *
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 3, or (at your option)
18 * any later version.
19 *
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.
24 *
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 */
28
29 #include <errno.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32
33 #include <sys/types.h>
34 #include <sys/time.h>
35 #include <netdb.h>
36 #include <sys/socket.h>
37 #include <netinet/in.h>
38 #include <arpa/inet.h>
39 #include <time.h>
40
41 #include "internal.h"
42 #include "tvarith.h"
43
44 /* TCP connection management. */
45
tcp_close(adns_state ads)46 static void tcp_close(adns_state ads) {
47 close(ads->tcpsocket);
48 ads->tcpsocket= -1;
49 ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
50 }
51
adns__tcp_broken(adns_state ads,const char * what,const char * why)52 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
53 int serv;
54 adns_query qu;
55
56 assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
57 serv= ads->tcpserver;
58 if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
59
60 if (ads->tcpstate == server_connecting) {
61 /* Counts as a retry for all the queries waiting for TCP. */
62 for (qu= ads->tcpw.head; qu; qu= qu->next)
63 qu->retries++;
64 }
65
66 tcp_close(ads);
67 ads->tcpstate= server_broken;
68 ads->tcpserver= (serv+1)%ads->nservers;
69 }
70
tcp_connected(adns_state ads,struct timeval now)71 static void tcp_connected(adns_state ads, struct timeval now) {
72 adns_query qu, nqu;
73
74 adns__debug(ads,ads->tcpserver,0,"TCP connected");
75 ads->tcpstate= server_ok;
76 for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
77 nqu= qu->next;
78 assert(qu->state == query_tcpw);
79 adns__querysend_tcp(qu,now);
80 }
81 }
82
tcp_broken_events(adns_state ads)83 static void tcp_broken_events(adns_state ads) {
84 adns_query qu, nqu;
85
86 assert(ads->tcpstate == server_broken);
87 for (qu= ads->tcpw.head; qu; qu= nqu) {
88 nqu= qu->next;
89 assert(qu->state == query_tcpw);
90 if (qu->retries > ads->nservers) {
91 LIST_UNLINK(ads->tcpw,qu);
92 adns__query_fail(qu,adns_s_allservfail);
93 }
94 }
95 ads->tcpstate= server_disconnected;
96 }
97
adns__tcp_tryconnect(adns_state ads,struct timeval now)98 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
99 int r, fd, tries;
100 adns_rr_addr *addr;
101 struct protoent *proto;
102
103 for (tries=0; tries<ads->nservers; tries++) {
104 switch (ads->tcpstate) {
105 case server_connecting:
106 case server_ok:
107 case server_broken:
108 return;
109 case server_disconnected:
110 break;
111 default:
112 abort();
113 }
114
115 assert(!ads->tcpsend.used);
116 assert(!ads->tcprecv.used);
117 assert(!ads->tcprecv_skip);
118
119 proto= getprotobyname("tcp");
120 if (!proto) {
121 adns__diag(ads,-1,0,"unable to find protocol no. for TCP !");
122 return;
123 }
124 addr = &ads->servers[ads->tcpserver];
125 fd= socket(addr->addr.sa.sa_family, SOCK_STREAM, proto->p_proto);
126 if (fd<0) {
127 adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
128 return;
129 }
130 r= adns__setnonblock(ads,fd);
131 if (r) {
132 adns__diag(ads,-1,0,"cannot make TCP socket nonblocking:"
133 " %s",strerror(r));
134 close(fd);
135 return;
136 }
137 r= connect(fd,&addr->addr.sa,addr->len);
138 ads->tcpsocket= fd;
139 ads->tcpstate= server_connecting;
140 if (r==0) { tcp_connected(ads,now); return; }
141 if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
142 ads->tcptimeout= now;
143 timevaladd(&ads->tcptimeout,TCPCONNMS);
144 return;
145 }
146 adns__tcp_broken(ads,"connect",strerror(errno));
147 tcp_broken_events(ads);
148 }
149 }
150
151 /* Timeout handling functions. */
152
adns__gettimeofday(adns_state ads,struct timeval * tv)153 int adns__gettimeofday(adns_state ads, struct timeval *tv) {
154 if (!(ads->iflags & adns_if_monotonic))
155 return gettimeofday(tv,0);
156
157 struct timespec ts;
158 int r = clock_gettime(CLOCK_MONOTONIC,&ts);
159 if (r) return r;
160
161 tv->tv_sec = ts.tv_sec;
162 tv->tv_usec = ts.tv_nsec / 1000;
163 return 0;
164 }
165
adns__must_gettimeofday(adns_state ads,const struct timeval ** now_io,struct timeval * tv_buf)166 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
167 struct timeval *tv_buf) {
168 const struct timeval *now;
169 int r;
170
171 now= *now_io;
172 if (now) return;
173 r= adns__gettimeofday(ads,tv_buf); if (!r) { *now_io= tv_buf; return; }
174 adns__diag(ads,-1,0,"gettimeofday/clock_gettime failed: %s",
175 strerror(errno));
176 adns_globalsystemfailure(ads);
177 return;
178 }
179
inter_immed(struct timeval ** tv_io,struct timeval * tvbuf)180 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
181 struct timeval *rbuf;
182
183 if (!tv_io) return;
184
185 rbuf= *tv_io;
186 if (!rbuf) { *tv_io= rbuf= tvbuf; }
187
188 timerclear(rbuf);
189 }
190
inter_maxto(struct timeval ** tv_io,struct timeval * tvbuf,struct timeval maxto)191 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
192 struct timeval maxto) {
193 struct timeval *rbuf;
194
195 if (!tv_io) return;
196 rbuf= *tv_io;
197 if (!rbuf) {
198 *tvbuf= maxto; *tv_io= tvbuf;
199 } else {
200 if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
201 }
202 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
203 maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
204 }
205
inter_maxtoabs(struct timeval ** tv_io,struct timeval * tvbuf,struct timeval now,struct timeval maxtime)206 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
207 struct timeval now, struct timeval maxtime) {
208 /* tv_io may be 0 */
209 ldiv_t dr;
210
211 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
212 now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
213 if (!tv_io) return;
214 maxtime.tv_sec -= (now.tv_sec+2);
215 maxtime.tv_usec -= (now.tv_usec-2000000);
216 dr= ldiv(maxtime.tv_usec,1000000);
217 maxtime.tv_sec += dr.quot;
218 maxtime.tv_usec -= dr.quot*1000000;
219 if (maxtime.tv_sec<0) timerclear(&maxtime);
220 inter_maxto(tv_io,tvbuf,maxtime);
221 }
222
timeouts_queue(adns_state ads,int act,struct timeval ** tv_io,struct timeval * tvbuf,struct timeval now,struct query_queue * queue)223 static void timeouts_queue(adns_state ads, int act,
224 struct timeval **tv_io, struct timeval *tvbuf,
225 struct timeval now, struct query_queue *queue) {
226 adns_query qu, nqu;
227 struct timeval expires;
228
229 for (qu= queue->head; qu; qu= nqu) {
230 nqu= qu->next;
231 if (timercmp(&now,&qu->timeout_started,<)) /* clock rewound */
232 qu->timeout_started= now;
233 expires= qu->timeout_started;
234 timevaladd(&expires, qu->timeout_ms);
235 if (!timercmp(&now,&expires,>)) {
236 inter_maxtoabs(tv_io,tvbuf,now,expires);
237 } else {
238 if (!act) { inter_immed(tv_io,tvbuf); return; }
239 LIST_UNLINK(*queue,qu);
240 if (qu->state != query_tosend) {
241 adns__query_fail(qu,adns_s_timeout);
242 } else {
243 adns__query_send(qu,now);
244 }
245 nqu= queue->head;
246 }
247 }
248 }
249
tcp_events(adns_state ads,int act,struct timeval ** tv_io,struct timeval * tvbuf,struct timeval now)250 static void tcp_events(adns_state ads, int act,
251 struct timeval **tv_io, struct timeval *tvbuf,
252 struct timeval now) {
253 for (;;) {
254 switch (ads->tcpstate) {
255 case server_broken:
256 if (!act) { inter_immed(tv_io,tvbuf); return; }
257 tcp_broken_events(ads);
258 case server_disconnected: /* fall through */
259 if (!ads->tcpw.head) return;
260 if (!act) { inter_immed(tv_io,tvbuf); return; }
261 adns__tcp_tryconnect(ads,now);
262 break;
263 case server_ok:
264 if (ads->tcpw.head) return;
265 if (!ads->tcptimeout.tv_sec) {
266 assert(!ads->tcptimeout.tv_usec);
267 ads->tcptimeout= now;
268 timevaladd(&ads->tcptimeout,TCPIDLEMS);
269 }
270 case server_connecting: /* fall through */
271 if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
272 inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
273 return;
274 } {
275 /* TCP timeout has happened */
276 switch (ads->tcpstate) {
277 case server_connecting: /* failed to connect */
278 adns__tcp_broken(ads,"unable to make connection","timed out");
279 break;
280 case server_ok: /* idle timeout */
281 tcp_close(ads);
282 ads->tcpstate= server_disconnected;
283 return;
284 default:
285 abort();
286 }
287 }
288 break;
289 default:
290 abort();
291 }
292 }
293 return;
294 }
295
adns__timeouts(adns_state ads,int act,struct timeval ** tv_io,struct timeval * tvbuf,struct timeval now)296 void adns__timeouts(adns_state ads, int act,
297 struct timeval **tv_io, struct timeval *tvbuf,
298 struct timeval now) {
299 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
300 timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
301 tcp_events(ads,act,tv_io,tvbuf,now);
302 }
303
adns_firsttimeout(adns_state ads,struct timeval ** tv_io,struct timeval * tvbuf,struct timeval now)304 void adns_firsttimeout(adns_state ads,
305 struct timeval **tv_io, struct timeval *tvbuf,
306 struct timeval now) {
307 adns__consistency(ads,0,cc_enter);
308 adns__timeouts(ads, 0, tv_io,tvbuf, now);
309 adns__returning(ads,0);
310 }
311
adns_processtimeouts(adns_state ads,const struct timeval * now)312 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
313 struct timeval tv_buf;
314
315 adns__consistency(ads,0,cc_enter);
316 adns__must_gettimeofday(ads,&now,&tv_buf);
317 if (now) adns__timeouts(ads, 1, 0,0, *now);
318 adns__returning(ads,0);
319 }
320
321 /* fd handling functions. These are the top-level of the real work of
322 * reception and often transmission.
323 */
324
adns__pollfds(adns_state ads,struct pollfd pollfds_buf[MAX_POLLFDS])325 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
326 /* Returns the number of entries filled in. Always zeroes revents. */
327 int nwanted=0;
328 #define ADD_POLLFD(wantfd, wantevents) do{ \
329 pollfds_buf[nwanted].fd= (wantfd); \
330 pollfds_buf[nwanted].events= (wantevents); \
331 pollfds_buf[nwanted].revents= 0; \
332 nwanted++; \
333 }while(0)
334
335 int i;
336
337 assert(MAX_POLLFDS == MAXUDP + 1);
338
339 for (i=0; i<ads->nudpsockets; i++)
340 ADD_POLLFD(ads->udpsockets[i].fd, POLLIN);
341
342 switch (ads->tcpstate) {
343 case server_disconnected:
344 case server_broken:
345 break;
346 case server_connecting:
347 ADD_POLLFD(ads->tcpsocket, POLLOUT);
348 break;
349 case server_ok:
350 ADD_POLLFD(ads->tcpsocket,
351 ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI);
352 break;
353 default:
354 abort();
355 }
356 assert(nwanted<=MAX_POLLFDS);
357 #undef ADD_POLLFD
358 return nwanted;
359 }
360
adns_processreadable(adns_state ads,int fd,const struct timeval * now)361 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
362 int want, dgramlen, r, i, serv, old_skip;
363 socklen_t udpaddrlen;
364 byte udpbuf[DNS_MAXUDP];
365 char addrbuf[ADNS_ADDR2TEXT_BUFLEN];
366 struct udpsocket *udp;
367 adns_sockaddr udpaddr;
368
369 adns__consistency(ads,0,cc_enter);
370
371 switch (ads->tcpstate) {
372 case server_disconnected:
373 case server_broken:
374 case server_connecting:
375 break;
376 case server_ok:
377 if (fd != ads->tcpsocket) break;
378 assert(!ads->tcprecv_skip);
379 do {
380 if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
381 dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
382 ads->tcprecv.buf[ads->tcprecv_skip+1]);
383 if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
384 old_skip= ads->tcprecv_skip;
385 ads->tcprecv_skip += 2+dgramlen;
386 adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
387 dgramlen, ads->tcpserver, 1,*now);
388 continue;
389 } else {
390 want= 2+dgramlen;
391 }
392 } else {
393 want= 2;
394 }
395 ads->tcprecv.used -= ads->tcprecv_skip;
396 memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
397 ads->tcprecv.used);
398 ads->tcprecv_skip= 0;
399 if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
400 assert(ads->tcprecv.used <= ads->tcprecv.avail);
401 if (ads->tcprecv.used == ads->tcprecv.avail) continue;
402 r= read(ads->tcpsocket,
403 ads->tcprecv.buf+ads->tcprecv.used,
404 ads->tcprecv.avail-ads->tcprecv.used);
405 if (r>0) {
406 ads->tcprecv.used+= r;
407 } else {
408 if (r) {
409 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
410 if (errno==EINTR) continue;
411 if (errno_resources(errno)) { r= errno; goto xit; }
412 }
413 adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
414 }
415 } while (ads->tcpstate == server_ok);
416 r= 0; goto xit;
417 default:
418 abort();
419 }
420 for (i=0; i<ads->nudpsockets; i++) {
421 udp= &ads->udpsockets[i];
422 if (fd != udp->fd) continue;
423 for (;;) {
424 udpaddrlen= sizeof(udpaddr);
425 r= recvfrom(fd,udpbuf,sizeof(udpbuf),0, &udpaddr.sa,&udpaddrlen);
426 if (r<0) {
427 if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
428 if (errno == EINTR) continue;
429 if (errno_resources(errno)) { r= errno; goto xit; }
430 adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
431 r= 0; goto xit;
432 }
433 for (serv= 0;
434 serv < ads->nservers &&
435 !adns__sockaddrs_equal(&udpaddr.sa,
436 &ads->servers[serv].addr.sa);
437 serv++);
438 if (serv >= ads->nservers) {
439 adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
440 adns__sockaddr_ntoa(&udpaddr.sa, addrbuf));
441 continue;
442 }
443 adns__procdgram(ads,udpbuf,r,serv,0,*now);
444 }
445 break;
446 }
447 r= 0;
448 xit:
449 adns__returning(ads,0);
450 return r;
451 }
452
adns_processwriteable(adns_state ads,int fd,const struct timeval * now)453 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
454 int r;
455
456 adns__consistency(ads,0,cc_enter);
457
458 switch (ads->tcpstate) {
459 case server_disconnected:
460 case server_broken:
461 break;
462 case server_connecting:
463 if (fd != ads->tcpsocket) break;
464 assert(ads->tcprecv.used==0);
465 assert(ads->tcprecv_skip==0);
466 for (;;) {
467 /* This function can be called even if the fd wasn't actually
468 * flagged as writeable. For asynch tcp connect we have to
469 * actually use the writeability to tell us the connect has
470 * completed (or failed), so we need to double check. */
471 fd_set writeable;
472 struct timeval timeout = { 0,0 };
473 FD_ZERO(&writeable);
474 FD_SET(ads->tcpsocket,&writeable);
475 r= select(ads->tcpsocket+1,0,&writeable,0,&timeout);
476 if (r==0) break;
477 if (r<0) {
478 if (errno==EINTR) continue;
479 adns__tcp_broken(ads,"select","failed connecting writeability check");
480 r= 0; goto xit;
481 }
482 assert(FD_ISSET(ads->tcpsocket,&writeable));
483 if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
484 r= read(ads->tcpsocket,ads->tcprecv.buf,1);
485 if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
486 tcp_connected(ads,*now);
487 r= 0; goto xit;
488 }
489 if (r>0) {
490 adns__tcp_broken(ads,"connect/read","sent data before first request");
491 r= 0; goto xit;
492 }
493 if (errno==EINTR) continue;
494 if (errno_resources(errno)) { r= errno; goto xit; }
495 adns__tcp_broken(ads,"connect/read",strerror(errno));
496 r= 0; goto xit;
497 } /* not reached */
498 case server_ok:
499 if (fd != ads->tcpsocket) break;
500 while (ads->tcpsend.used) {
501 adns__sigpipe_protect(ads);
502 r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
503 adns__sigpipe_unprotect(ads);
504 if (r<0) {
505 if (errno==EINTR) continue;
506 if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
507 if (errno_resources(errno)) { r= errno; goto xit; }
508 adns__tcp_broken(ads,"write",strerror(errno));
509 r= 0; goto xit;
510 } else if (r>0) {
511 assert(r <= ads->tcpsend.used);
512 ads->tcpsend.used -= r;
513 memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
514 }
515 }
516 r= 0;
517 goto xit;
518 default:
519 abort();
520 }
521 r= 0;
522 xit:
523 adns__returning(ads,0);
524 return r;
525 }
526
adns_processexceptional(adns_state ads,int fd,const struct timeval * now)527 int adns_processexceptional(adns_state ads, int fd,
528 const struct timeval *now) {
529 adns__consistency(ads,0,cc_enter);
530 switch (ads->tcpstate) {
531 case server_disconnected:
532 case server_broken:
533 break;
534 case server_connecting:
535 case server_ok:
536 if (fd != ads->tcpsocket) break;
537 adns__tcp_broken(ads,"poll/select","exceptional condition detected");
538 break;
539 default:
540 abort();
541 }
542 adns__returning(ads,0);
543 return 0;
544 }
545
fd_event(adns_state ads,int fd,int revent,int pollflag,int maxfd,const fd_set * fds,int (* func)(adns_state,int fd,const struct timeval * now),struct timeval now,int * r_r)546 static void fd_event(adns_state ads, int fd,
547 int revent, int pollflag,
548 int maxfd, const fd_set *fds,
549 int (*func)(adns_state, int fd,
550 const struct timeval *now),
551 struct timeval now, int *r_r) {
552 int r;
553
554 if (!(revent & pollflag)) return;
555 if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
556 r= func(ads,fd,&now);
557 if (r) {
558 if (r_r) {
559 *r_r= r;
560 } else {
561 adns__diag(ads,-1,0,"process fd failed after select:"
562 " %s",strerror(errno));
563 adns_globalsystemfailure(ads);
564 }
565 }
566 }
567
adns__fdevents(adns_state ads,const struct pollfd * pollfds,int npollfds,int maxfd,const fd_set * readfds,const fd_set * writefds,const fd_set * exceptfds,struct timeval now,int * r_r)568 void adns__fdevents(adns_state ads,
569 const struct pollfd *pollfds, int npollfds,
570 int maxfd, const fd_set *readfds,
571 const fd_set *writefds, const fd_set *exceptfds,
572 struct timeval now, int *r_r) {
573 int i, fd, revents;
574
575 for (i=0; i<npollfds; i++) {
576 fd= pollfds[i].fd;
577 if (fd >= maxfd) maxfd= fd+1;
578 revents= pollfds[i].revents;
579 #define EV(pollfl,fds,how) \
580 fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
581 EV( POLLIN, readfds, readable );
582 EV( POLLOUT, writefds, writeable );
583 EV( POLLPRI, exceptfds, exceptional );
584 #undef EV
585 }
586 }
587
588 /* Wrappers for select(2). */
589
adns_beforeselect(adns_state ads,int * maxfd_io,fd_set * readfds_io,fd_set * writefds_io,fd_set * exceptfds_io,struct timeval ** tv_mod,struct timeval * tv_tobuf,const struct timeval * now)590 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
591 fd_set *writefds_io, fd_set *exceptfds_io,
592 struct timeval **tv_mod, struct timeval *tv_tobuf,
593 const struct timeval *now) {
594 struct timeval tv_nowbuf;
595 struct pollfd pollfds[MAX_POLLFDS];
596 int i, fd, maxfd, npollfds;
597
598 adns__consistency(ads,0,cc_enter);
599
600 if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
601 /* The caller is planning to sleep. */
602 adns__must_gettimeofday(ads,&now,&tv_nowbuf);
603 if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
604 adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
605 }
606
607 npollfds= adns__pollfds(ads,pollfds);
608 maxfd= *maxfd_io;
609 for (i=0; i<npollfds; i++) {
610 fd= pollfds[i].fd;
611 if (fd >= maxfd) maxfd= fd+1;
612 if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
613 if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
614 if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
615 }
616 *maxfd_io= maxfd;
617
618 xit:
619 adns__returning(ads,0);
620 }
621
adns_afterselect(adns_state ads,int maxfd,const fd_set * readfds,const fd_set * writefds,const fd_set * exceptfds,const struct timeval * now)622 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
623 const fd_set *writefds, const fd_set *exceptfds,
624 const struct timeval *now) {
625 struct timeval tv_buf;
626 struct pollfd pollfds[MAX_POLLFDS];
627 int npollfds, i;
628
629 adns__consistency(ads,0,cc_enter);
630 adns__must_gettimeofday(ads,&now,&tv_buf);
631 if (!now) goto xit;
632 adns_processtimeouts(ads,now);
633
634 npollfds= adns__pollfds(ads,pollfds);
635 for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
636 adns__fdevents(ads,
637 pollfds,npollfds,
638 maxfd,readfds,writefds,exceptfds,
639 *now, 0);
640 xit:
641 adns__returning(ads,0);
642 }
643
644 /* General helpful functions. */
645
adns_globalsystemfailure(adns_state ads)646 void adns_globalsystemfailure(adns_state ads) {
647 /* Must not be called by adns during actual processing of a
648 * particular query, since it reenters adns. Only safe to call in
649 * situations where it would be safe to call adns_returning. */
650 adns__consistency(ads,0,cc_enter);
651
652 for (;;) {
653 adns_query qu;
654 #define GSF_QQ(QQ) \
655 if ((qu= ads->QQ.head)) { \
656 LIST_UNLINK(ads->QQ,qu); \
657 adns__query_fail(qu, adns_s_systemfail); \
658 continue; \
659 }
660 GSF_QQ(udpw);
661 GSF_QQ(tcpw);
662 #undef GSF_QQ
663 break;
664 }
665
666 switch (ads->tcpstate) {
667 case server_connecting:
668 case server_ok:
669 adns__tcp_broken(ads,0,0);
670 break;
671 case server_disconnected:
672 case server_broken:
673 break;
674 default:
675 abort();
676 }
677 adns__returning(ads,0);
678 }
679
adns_processany(adns_state ads)680 int adns_processany(adns_state ads) {
681 int r, i;
682 struct timeval now;
683 struct pollfd pollfds[MAX_POLLFDS];
684 int npollfds;
685
686 adns__consistency(ads,0,cc_enter);
687
688 r= adns__gettimeofday(ads,&now);
689 if (!r) adns_processtimeouts(ads,&now);
690
691 /* We just use adns__fdevents to loop over the fd's trying them.
692 * This seems more sensible than calling select, since we're most
693 * likely just to want to do a read on one or two fds anyway.
694 */
695 npollfds= adns__pollfds(ads,pollfds);
696 for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
697 adns__fdevents(ads,
698 pollfds,npollfds,
699 0,0,0,0,
700 now,&r);
701
702 adns__returning(ads,0);
703 return 0;
704 }
705
adns__autosys(adns_state ads,struct timeval now)706 void adns__autosys(adns_state ads, struct timeval now) {
707 if (ads->iflags & adns_if_noautosys) return;
708 adns_processany(ads);
709 }
710
adns__internal_check(adns_state ads,adns_query * query_io,adns_answer ** answer,void ** context_r)711 int adns__internal_check(adns_state ads,
712 adns_query *query_io,
713 adns_answer **answer,
714 void **context_r) {
715 adns_query qu;
716
717 qu= *query_io;
718 if (!qu) {
719 if (ads->output.head) {
720 qu= ads->output.head;
721 } else if (ads->udpw.head || ads->tcpw.head) {
722 return EAGAIN;
723 } else {
724 return ESRCH;
725 }
726 } else {
727 if (qu->id>=0) return EAGAIN;
728 }
729 LIST_UNLINK(ads->output,qu);
730 *answer= qu->answer;
731 if (context_r) *context_r= qu->ctx.ext;
732 *query_io= qu;
733 free(qu);
734 return 0;
735 }
736
adns_wait(adns_state ads,adns_query * query_io,adns_answer ** answer_r,void ** context_r)737 int adns_wait(adns_state ads,
738 adns_query *query_io,
739 adns_answer **answer_r,
740 void **context_r) {
741 int r, maxfd, rsel;
742 fd_set readfds, writefds, exceptfds;
743 struct timeval tvbuf, *tvp;
744
745 adns__consistency(ads,*query_io,cc_enter);
746 for (;;) {
747 r= adns__internal_check(ads,query_io,answer_r,context_r);
748 if (r != EAGAIN) break;
749 maxfd= 0; tvp= 0;
750 FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
751 adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
752 assert(tvp);
753 rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
754 if (rsel==-1) {
755 if (errno == EINTR) {
756 if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
757 } else {
758 adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
759 adns_globalsystemfailure(ads);
760 }
761 } else {
762 assert(rsel >= 0);
763 adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
764 }
765 }
766 adns__returning(ads,0);
767 return r;
768 }
769
adns_check(adns_state ads,adns_query * query_io,adns_answer ** answer_r,void ** context_r)770 int adns_check(adns_state ads,
771 adns_query *query_io,
772 adns_answer **answer_r,
773 void **context_r) {
774 struct timeval now;
775 int r;
776
777 adns__consistency(ads,*query_io,cc_enter);
778 r= adns__gettimeofday(ads,&now);
779 if (!r) adns__autosys(ads,now);
780
781 r= adns__internal_check(ads,query_io,answer_r,context_r);
782 adns__returning(ads,0);
783 return r;
784 }
785