mdw@git.distorted.org.uk Git - adns/blob - src/event.c

   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
   9  *    Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
  10  *
  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>
  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 2, 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  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  28  */
  29
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #include <unistd.h>
  33
  34 #include <sys/types.h>
  35 #include <sys/time.h>
  36 #include <netdb.h>
  37 #include <sys/socket.h>
  38 #include <netinet/in.h>
  39 #include <arpa/inet.h>
  40
  41 #include "internal.h"
  42 #include "tvarith.h"
  43
  44 /* TCP connection management. */
  45
  46 static void tcp_close(adns_state ads) {
  47   int serv;
  48
  49   serv= ads->tcpserver;
  50   close(ads->tcpsocket);
  51   ads->tcpsocket= -1;
  52   ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
  53 }
  54
  55 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
  56   int serv;
  57
  58   assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
  59   serv= ads->tcpserver;
  60   if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
  61
  62   tcp_close(ads);
  63   ads->tcpstate= server_broken;
  64   ads->tcpserver= (serv+1)%ads->nservers;
  65 }
  66
  67 static void tcp_connected(adns_state ads, struct timeval now) {
  68   adns_query qu, nqu;
  69
  70   adns__debug(ads,ads->tcpserver,0,"TCP connected");
  71   ads->tcpstate= server_ok;
  72   for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
  73     nqu= qu->next;
  74     assert(qu->state == query_tcpw);
  75     adns__querysend_tcp(qu,now);
  76   }
  77 }
  78
  79 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
  80   int r, fd, tries;
  81   struct sockaddr_in addr;
  82   struct protoent *proto;
  83
  84   for (tries=0; tries<ads->nservers; tries++) {
  85     switch (ads->tcpstate) {
  86     case server_connecting:
  87     case server_ok:
  88     case server_broken:
  89       return;
  90     case server_disconnected:
  91       break;
  92     default:
  93       abort();
  94     }
  95
  96     assert(!ads->tcpsend.used);
  97     assert(!ads->tcprecv.used);
  98     assert(!ads->tcprecv_skip);
  99
 100     proto= getprotobyname("tcp");
 101     if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
 102     fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
 103     if (fd<0) {
 104       adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
 105       return;
 106     }
 107     r= adns__setnonblock(ads,fd);
 108     if (r) {
 109       adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
 110       close(fd);
 111       return;
 112     }
 113     memset(&addr,0,sizeof(addr));
 114     addr.sin_family= AF_INET;
 115     addr.sin_port= htons(DNS_PORT);
 116     addr.sin_addr= ads->servers[ads->tcpserver].addr;
 117     r= connect(fd,(const struct sockaddr*)&addr,sizeof(addr));
 118     ads->tcpsocket= fd;
 119     ads->tcpstate= server_connecting;
 120     if (r==0) { tcp_connected(ads,now); return; }
 121     if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
 122       ads->tcptimeout= now;
 123       timevaladd(&ads->tcptimeout,TCPCONNMS);
 124       return;
 125     }
 126     adns__tcp_broken(ads,"connect",strerror(errno));
 127     ads->tcpstate= server_disconnected;
 128   }
 129 }
 130
 131 /* Timeout handling functions. */
 132
 133 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
 134                              struct timeval *tv_buf) {
 135   const struct timeval *now;
 136   int r;
 137
 138   now= *now_io;
 139   if (now) return;
 140   r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
 141   adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
 142   adns_globalsystemfailure(ads);
 143   return;
 144 }
 145
 146 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
 147                         struct timeval maxto) {
 148   struct timeval *rbuf;
 149
 150   if (!tv_io) return;
 151   rbuf= *tv_io;
 152   if (!rbuf) {
 153     *tvbuf= maxto; *tv_io= tvbuf;
 154   } else {
 155     if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 156   }
 157 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
 158         maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
 159 }
 160
 161 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 162                            struct timeval now, struct timeval maxtime) {
 163   /* tv_io may be 0 */
 164   ldiv_t dr;
 165
 166 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
 167         now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
 168   if (!tv_io) return;
 169   maxtime.tv_sec -= (now.tv_sec+2);
 170   maxtime.tv_usec -= (now.tv_usec-2000000);
 171   dr= ldiv(maxtime.tv_usec,1000000);
 172   maxtime.tv_sec += dr.quot;
 173   maxtime.tv_usec -= dr.quot*1000000;
 174   if (maxtime.tv_sec<0) timerclear(&maxtime);
 175   inter_maxto(tv_io,tvbuf,maxtime);
 176 }
 177
 178 static void timeouts_queue(adns_state ads, int act,
 179                            struct timeval **tv_io, struct timeval *tvbuf,
 180                            struct timeval now, struct query_queue *queue) {
 181   adns_query qu, nqu;
 182
 183   for (qu= queue->head; qu; qu= nqu) {
 184     nqu= qu->next;
 185     if (!timercmp(&now,&qu->timeout,>)) {
 186       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 187     } else {
 188       if (!act) {
 189         tvbuf->tv_sec= 0;
 190         tvbuf->tv_usec= 0;
 191         *tv_io= tvbuf;
 192         return;
 193       }
 194       LIST_UNLINK(*queue,qu);
 195       if (qu->state != query_tosend) {
 196         adns__query_fail(qu,adns_s_timeout);
 197       } else {
 198         adns__query_send(qu,now);
 199       }
 200       nqu= queue->head;
 201     }
 202   }
 203 }
 204
 205 static void tcp_events(adns_state ads, int act,
 206                        struct timeval **tv_io, struct timeval *tvbuf,
 207                        struct timeval now) {
 208   adns_query qu, nqu;
 209
 210   for (;;) {
 211     switch (ads->tcpstate) {
 212     case server_broken:
 213       for (qu= ads->tcpw.head; qu; qu= nqu) {
 214         nqu= qu->next;
 215         assert(qu->state == query_tcpw);
 216         if (qu->retries > ads->nservers) {
 217           LIST_UNLINK(ads->tcpw,qu);
 218           adns__query_fail(qu,adns_s_allservfail);
 219         }
 220       }
 221       ads->tcpstate= server_disconnected;
 222     case server_disconnected: /* fall through */
 223       if (!ads->tcpw.head) return;
 224       adns__tcp_tryconnect(ads,now);
 225       break;
 226     case server_ok:
 227       if (ads->tcpw.head) return;
 228       if (!ads->tcptimeout.tv_sec) {
 229         assert(!ads->tcptimeout.tv_usec);
 230         ads->tcptimeout= now;
 231         timevaladd(&ads->tcptimeout,TCPIDLEMS);
 232       }
 233     case server_connecting: /* fall through */
 234       if (!timercmp(&now,&ads->tcptimeout,>)) {
 235         inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
 236         return;
 237       } {
 238         /* TCP timeout has happened */
 239         switch (ads->tcpstate) {
 240         case server_connecting: /* failed to connect */
 241           adns__tcp_broken(ads,"unable to make connection","timed out");
 242           break;
 243         case server_ok: /* idle timeout */
 244           tcp_close(ads);
 245           ads->tcpstate= server_disconnected;
 246           return;
 247         default:
 248           abort();
 249         }
 250       }
 251       break;
 252     default:
 253       abort();
 254     }
 255   }
 256 }
 257
 258 void adns__timeouts(adns_state ads, int act,
 259                     struct timeval **tv_io, struct timeval *tvbuf,
 260                     struct timeval now) {
 261   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
 262   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
 263   tcp_events(ads,act,tv_io,tvbuf,now);
 264 }
 265
 266 void adns_firsttimeout(adns_state ads,
 267                        struct timeval **tv_io, struct timeval *tvbuf,
 268                        struct timeval now) {
 269   adns__consistency(ads,0,cc_entex);
 270   adns__timeouts(ads, 0, tv_io,tvbuf, now);
 271   adns__consistency(ads,0,cc_entex);
 272 }
 273
 274 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
 275   struct timeval tv_buf;
 276
 277   adns__consistency(ads,0,cc_entex);
 278   adns__must_gettimeofday(ads,&now,&tv_buf);
 279   if (now) adns__timeouts(ads, 1, 0,0, *now);
 280   adns__consistency(ads,0,cc_entex);
 281 }
 282
 283 /* fd handling functions.  These are the top-level of the real work of
 284  * reception and often transmission.
 285  */
 286
 287 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
 288   /* Returns the number of entries filled in.  Always zeroes revents. */
 289
 290   assert(MAX_POLLFDS==2);
 291
 292   pollfds_buf[0].fd= ads->udpsocket;
 293   pollfds_buf[0].events= POLLIN;
 294   pollfds_buf[0].revents= 0;
 295
 296   switch (ads->tcpstate) {
 297   case server_disconnected:
 298     return 1;
 299   case server_connecting:
 300     pollfds_buf[1].events= POLLOUT;
 301     break;
 302   case server_ok:
 303     pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
 304     break;
 305   default:
 306     abort();
 307   }
 308   pollfds_buf[1].fd= ads->tcpsocket;
 309   return 2;
 310 }
 311
 312 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
 313   int want, dgramlen, r, udpaddrlen, serv, old_skip;
 314   byte udpbuf[DNS_MAXUDP];
 315   struct sockaddr_in udpaddr;
 316
 317   adns__consistency(ads,0,cc_entex);
 318
 319   switch (ads->tcpstate) {
 320   case server_disconnected:
 321   case server_connecting:
 322     break;
 323   case server_ok:
 324     if (fd != ads->tcpsocket) break;
 325     assert(!ads->tcprecv_skip);
 326     for (;;) {
 327       if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
 328         dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
 329                    ads->tcprecv.buf[ads->tcprecv_skip+1]);
 330         if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
 331           old_skip= ads->tcprecv_skip;
 332           ads->tcprecv_skip += 2+dgramlen;
 333           adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
 334                           dgramlen, ads->tcpserver, 1,*now);
 335           continue;
 336         } else {
 337           want= 2+dgramlen;
 338         }
 339       } else {
 340         want= 2;
 341       }
 342       ads->tcprecv.used -= ads->tcprecv_skip;
 343       memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
 344       ads->tcprecv_skip= 0;
 345       if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
 346       assert(ads->tcprecv.used <= ads->tcprecv.avail);
 347       if (ads->tcprecv.used == ads->tcprecv.avail) continue;
 348       r= read(ads->tcpsocket,
 349               ads->tcprecv.buf+ads->tcprecv.used,
 350               ads->tcprecv.avail-ads->tcprecv.used);
 351       if (r>0) {
 352         ads->tcprecv.used+= r;
 353       } else {
 354         if (r) {
 355           if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 356           if (errno==EINTR) continue;
 357           if (errno_resources(errno)) { r= errno; goto xit; }
 358         }
 359         adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
 360         r= 0; goto xit;
 361       }
 362     } /* never reached */
 363   default:
 364     abort();
 365   }
 366   if (fd == ads->udpsocket) {
 367     for (;;) {
 368       udpaddrlen= sizeof(udpaddr);
 369       r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
 370                   (struct sockaddr*)&udpaddr,&udpaddrlen);
 371       if (r<0) {
 372         if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
 373         if (errno == EINTR) continue;
 374         if (errno_resources(errno)) { r= errno; goto xit; }
 375         adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
 376         r= 0; goto xit;
 377       }
 378       if (udpaddrlen != sizeof(udpaddr)) {
 379         adns__diag(ads,-1,0,"datagram received with wrong address length %d"
 380                    " (expected %d)", udpaddrlen,sizeof(udpaddr));
 381         continue;
 382       }
 383       if (udpaddr.sin_family != AF_INET) {
 384         adns__diag(ads,-1,0,"datagram received with wrong protocol family"
 385                    " %u (expected %u)",udpaddr.sin_family,AF_INET);
 386         continue;
 387       }
 388       if (ntohs(udpaddr.sin_port) != DNS_PORT) {
 389         adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
 390                    ntohs(udpaddr.sin_port),DNS_PORT);
 391         continue;
 392       }
 393       for (serv= 0;
 394            serv < ads->nservers &&
 395              ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
 396            serv++);
 397       if (serv >= ads->nservers) {
 398         adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
 399                    inet_ntoa(udpaddr.sin_addr));
 400         continue;
 401       }
 402       adns__procdgram(ads,udpbuf,r,serv,0,*now);
 403     }
 404   }
 405   r= 0;
 406 xit:
 407   adns__consistency(ads,0,cc_entex);
 408   return r;
 409 }
 410
 411 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
 412   int r;
 413
 414   adns__consistency(ads,0,cc_entex);
 415
 416   switch (ads->tcpstate) {
 417   case server_disconnected:
 418     break;
 419   case server_connecting:
 420     if (fd != ads->tcpsocket) break;
 421     assert(ads->tcprecv.used==0);
 422     assert(ads->tcprecv_skip==0);
 423     for (;;) {
 424       if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
 425       r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
 426       if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
 427         tcp_connected(ads,*now);
 428         r= 0; goto xit;
 429       }
 430       if (r>0) {
 431         adns__tcp_broken(ads,"connect/read","sent data before first request");
 432         r= 0; goto xit;
 433       }
 434       if (errno==EINTR) continue;
 435       if (errno_resources(errno)) { r= errno; goto xit; }
 436       adns__tcp_broken(ads,"connect/read",strerror(errno));
 437       r= 0; goto xit;
 438     } /* not reached */
 439   case server_ok:
 440     if (!(ads->tcpsend.used && fd == ads->tcpsocket)) break;
 441     for (;;) {
 442       adns__sigpipe_protect(ads);
 443       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
 444       adns__sigpipe_unprotect(ads);
 445       if (r<0) {
 446         if (errno==EINTR) continue;
 447         if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 448         if (errno_resources(errno)) { r= errno; goto xit; }
 449         adns__tcp_broken(ads,"write",strerror(errno));
 450         r= 0; goto xit;
 451       } else if (r>0) {
 452         ads->tcpsend.used -= r;
 453         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 454       }
 455     } /* not reached */
 456   default:
 457     abort();
 458   }
 459   r= 0;
 460 xit:
 461   adns__consistency(ads,0,cc_entex);
 462   return r;
 463 }
 464
 465 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
 466   adns__consistency(ads,0,cc_entex);
 467   switch (ads->tcpstate) {
 468   case server_disconnected:
 469     break;
 470   case server_connecting:
 471   case server_ok:
 472     if (fd != ads->tcpsocket) break;
 473     adns__tcp_broken(ads,"poll/select","exceptional condition detected");
 474     break;
 475   default:
 476     abort();
 477   }
 478   adns__consistency(ads,0,cc_entex);
 479   return 0;
 480 }
 481
 482 static void fd_event(adns_state ads, int fd,
 483                      int revent, int pollflag,
 484                      int maxfd, const fd_set *fds,
 485                      int (*func)(adns_state, int fd, const struct timeval *now),
 486                      struct timeval now, int *r_r) {
 487   int r;
 488
 489   if (!(revent & pollflag)) return;
 490   if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
 491   r= func(ads,fd,&now);
 492   if (r) {
 493     if (r_r) {
 494       *r_r= r;
 495     } else {
 496       adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
 497       adns_globalsystemfailure(ads);
 498     }
 499   }
 500 }
 501
 502 void adns__fdevents(adns_state ads,
 503                     const struct pollfd *pollfds, int npollfds,
 504                     int maxfd, const fd_set *readfds,
 505                     const fd_set *writefds, const fd_set *exceptfds,
 506                     struct timeval now, int *r_r) {
 507   int i, fd, revents;
 508
 509   for (i=0; i<npollfds; i++) {
 510     fd= pollfds[i].fd;
 511     if (fd >= maxfd) maxfd= fd+1;
 512     revents= pollfds[i].revents;
 513     fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
 514     fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
 515     fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
 516   }
 517 }
 518
 519 /* Wrappers for select(2). */
 520
 521 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
 522                        fd_set *writefds_io, fd_set *exceptfds_io,
 523                        struct timeval **tv_mod, struct timeval *tv_tobuf,
 524                        const struct timeval *now) {
 525   struct timeval tv_nowbuf;
 526   struct pollfd pollfds[MAX_POLLFDS];
 527   int i, fd, maxfd, npollfds;
 528
 529   adns__consistency(ads,0,cc_entex);
 530
 531   if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
 532     /* The caller is planning to sleep. */
 533     adns__must_gettimeofday(ads,&now,&tv_nowbuf);
 534     if (!now) { inter_immed(tv_mod,tv_iobuf); goto xit; }
 535     adns__timeouts(ads, 1, tv_mod,tv_tobuf, *now);
 536   }
 537
 538   npollfds= adns__pollfds(ads,pollfds);
 539   maxfd= *maxfd_io;
 540   for (i=0; i<npollfds; i++) {
 541     fd= pollfds[i].fd;
 542     if (fd >= maxfd) maxfd= fd+1;
 543     if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
 544     if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
 545     if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
 546   }
 547   *maxfd_io= maxfd;
 548
 549 xit:
 550   adns__consistency(ads,0,cc_entex);
 551 }
 552
 553 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
 554                       const fd_set *writefds, const fd_set *exceptfds,
 555                       const struct timeval *now) {
 556   struct timeval tv_buf;
 557   struct pollfd pollfds[MAX_POLLFDS];
 558   int npollfds, i;
 559
 560   adns__consistency(ads,0,cc_entex);
 561   adns__must_gettimeofday(ads,&now,&tv_buf);
 562   if (!now) goto xit;
 563   adns_processtimeouts(ads,now);
 564
 565   npollfds= adns__pollfds(ads,pollfds);
 566   for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
 567   adns__fdevents(ads,
 568                  pollfds,npollfds,
 569                  maxfd,readfds,writefds,exceptfds,
 570                  *now, 0);
 571 xit:
 572   adns__consistency(ads,0,cc_entex);
 573 }
 574
 575 /* General helpful functions. */
 576
 577 void adns_globalsystemfailure(adns_state ads) {
 578   adns__consistency(ads,0,cc_entex);
 579
 580   while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
 581   while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
 582
 583   switch (ads->tcpstate) {
 584   case server_connecting:
 585   case server_ok:
 586     adns__tcp_broken(ads,0,0);
 587     break;
 588   case server_disconnected:
 589     break;
 590   default:
 591     abort();
 592   }
 593   adns__consistency(ads,0,cc_entex);
 594 }
 595
 596 int adns_processany(adns_state ads) {
 597   int r, i;
 598   struct timeval now;
 599   struct pollfd pollfds[MAX_POLLFDS];
 600   int npollfds;
 601
 602   adns__consistency(ads,0,cc_entex);
 603
 604   r= gettimeofday(&now,0);
 605   if (!r) adns_processtimeouts(ads,&now);
 606
 607   /* We just use adns__fdevents to loop over the fd's trying them.
 608    * This seems more sensible than calling select, since we're most
 609    * likely just to want to do a read on one or two fds anyway.
 610    */
 611   npollfds= adns__pollfds(ads,pollfds);
 612   for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events;
 613   adns__fdevents(ads,
 614                  pollfds,npollfds,
 615                  0,0,0,0,
 616                  now,&r);
 617
 618   adns__consistency(ads,0,cc_entex);
 619   return 0;
 620 }
 621
 622 void adns__autosys(adns_state ads, struct timeval now) {
 623   if (ads->iflags & adns_if_noautosys) return;
 624   adns_processany(ads);
 625 }
 626
 627 int adns__internal_check(adns_state ads,
 628                          adns_query *query_io,
 629                          adns_answer **answer,
 630                          void **context_r) {
 631   adns_query qu;
 632
 633   qu= *query_io;
 634   if (!qu) {
 635     if (ads->output.head) {
 636       qu= ads->output.head;
 637     } else if (ads->udpw.head || ads->tcpw.head) {
 638       return EAGAIN;
 639     } else {
 640       return ESRCH;
 641     }
 642   } else {
 643     if (qu->id>=0) return EAGAIN;
 644   }
 645   LIST_UNLINK(ads->output,qu);
 646   *answer= qu->answer;
 647   if (context_r) *context_r= qu->ctx.ext;
 648   *query_io= qu;
 649   free(qu);
 650   return 0;
 651 }
 652
 653 int adns_wait(adns_state ads,
 654               adns_query *query_io,
 655               adns_answer **answer_r,
 656               void **context_r) {
 657   int r, maxfd, rsel;
 658   fd_set readfds, writefds, exceptfds;
 659   struct timeval *now, nowbuf, tvbuf, *tvp;
 660
 661   adns__consistency(ads,*query_io,cc_entex);
 662   for (;;) {
 663     r= adns__internal_check(ads,query_io,answer_r,context_r);
 664     if (r != EAGAIN) break;
 665     maxfd= 0; tvp= 0;
 666     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 667     adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
 668     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 669     if (rsel==-1) {
 670       if (errno == EINTR) {
 671         if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
 672       } else {
 673         adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
 674         adns_globalsystemfailure(ads);
 675       }
 676     } else {
 677       assert(rsel >= 0);
 678       adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
 679     }
 680   }
 681   adns__consistency(ads,0,cc_entex);
 682   return r;
 683 }
 684
 685 int adns_check(adns_state ads,
 686                adns_query *query_io,
 687                adns_answer **answer_r,
 688                void **context_r) {
 689   struct timeval now;
 690   int r;
 691
 692   adns__consistency(ads,*query_io,cc_entex);
 693   r= gettimeofday(&now,0);
 694   if (!r) adns__autosys(ads,now);
 695
 696   r= adns__internal_check(ads,query_io,answer_r,context_r);
 697   adns__consistency(ads,0,cc_entex);
 698   return r;
 699 }