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_immed(struct timeval **tv_io, struct timeval *tvbuf) {
 147   struct timeval *rbuf;
 148
 149   if (!tv_io) return;
 150
 151   rbuf= *tv_io;
 152   if (!rbuf) { *tv_io= rbuf= tvbuf; }
 153
 154   timerclear(rbuf);
 155 }
 156
 157 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
 158                         struct timeval maxto) {
 159   struct timeval *rbuf;
 160
 161   if (!tv_io) return;
 162   rbuf= *tv_io;
 163   if (!rbuf) {
 164     *tvbuf= maxto; *tv_io= tvbuf;
 165   } else {
 166     if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 167   }
 168 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
 169         maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
 170 }
 171
 172 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 173                            struct timeval now, struct timeval maxtime) {
 174   /* tv_io may be 0 */
 175   ldiv_t dr;
 176
 177 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
 178         now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
 179   if (!tv_io) return;
 180   maxtime.tv_sec -= (now.tv_sec+2);
 181   maxtime.tv_usec -= (now.tv_usec-2000000);
 182   dr= ldiv(maxtime.tv_usec,1000000);
 183   maxtime.tv_sec += dr.quot;
 184   maxtime.tv_usec -= dr.quot*1000000;
 185   if (maxtime.tv_sec<0) timerclear(&maxtime);
 186   inter_maxto(tv_io,tvbuf,maxtime);
 187 }
 188
 189 static void timeouts_queue(adns_state ads, int act,
 190                            struct timeval **tv_io, struct timeval *tvbuf,
 191                            struct timeval now, struct query_queue *queue) {
 192   adns_query qu, nqu;
 193
 194   for (qu= queue->head; qu; qu= nqu) {
 195     nqu= qu->next;
 196     if (!timercmp(&now,&qu->timeout,>)) {
 197       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 198     } else {
 199       if (!act) { inter_immed(tv_io,tvbuf); return; }
 200       LIST_UNLINK(*queue,qu);
 201       if (qu->state != query_tosend) {
 202         adns__query_fail(qu,adns_s_timeout);
 203       } else {
 204         adns__query_send(qu,now);
 205       }
 206       nqu= queue->head;
 207     }
 208   }
 209 }
 210
 211 static void tcp_events(adns_state ads, int act,
 212                        struct timeval **tv_io, struct timeval *tvbuf,
 213                        struct timeval now) {
 214   adns_query qu, nqu;
 215
 216   for (;;) {
 217     switch (ads->tcpstate) {
 218     case server_broken:
 219       if (!act) { inter_immed(tv_io,tvbuf); return; }
 220       for (qu= ads->tcpw.head; qu; qu= nqu) {
 221         nqu= qu->next;
 222         assert(qu->state == query_tcpw);
 223         if (qu->retries > ads->nservers) {
 224           LIST_UNLINK(ads->tcpw,qu);
 225           adns__query_fail(qu,adns_s_allservfail);
 226         }
 227       }
 228       ads->tcpstate= server_disconnected;
 229     case server_disconnected: /* fall through */
 230       if (!ads->tcpw.head) return;
 231       if (!act) { inter_immed(tv_io,tvbuf); return; }
 232       adns__tcp_tryconnect(ads,now);
 233       break;
 234     case server_ok:
 235       if (ads->tcpw.head) return;
 236       if (!ads->tcptimeout.tv_sec) {
 237         assert(!ads->tcptimeout.tv_usec);
 238         ads->tcptimeout= now;
 239         timevaladd(&ads->tcptimeout,TCPIDLEMS);
 240       }
 241     case server_connecting: /* fall through */
 242       if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
 243         inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
 244         return;
 245       } {
 246         /* TCP timeout has happened */
 247         switch (ads->tcpstate) {
 248         case server_connecting: /* failed to connect */
 249           adns__tcp_broken(ads,"unable to make connection","timed out");
 250           break;
 251         case server_ok: /* idle timeout */
 252           tcp_close(ads);
 253           ads->tcpstate= server_disconnected;
 254           return;
 255         default:
 256           abort();
 257         }
 258       }
 259       break;
 260     default:
 261       abort();
 262     }
 263   }
 264   return;
 265 }
 266
 267 void adns__timeouts(adns_state ads, int act,
 268                     struct timeval **tv_io, struct timeval *tvbuf,
 269                     struct timeval now) {
 270   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
 271   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
 272   tcp_events(ads,act,tv_io,tvbuf,now);
 273 }
 274
 275 void adns_firsttimeout(adns_state ads,
 276                        struct timeval **tv_io, struct timeval *tvbuf,
 277                        struct timeval now) {
 278   adns__consistency(ads,0,cc_entex);
 279   adns__timeouts(ads, 0, tv_io,tvbuf, now);
 280   adns__consistency(ads,0,cc_entex);
 281 }
 282
 283 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
 284   struct timeval tv_buf;
 285
 286   adns__consistency(ads,0,cc_entex);
 287   adns__must_gettimeofday(ads,&now,&tv_buf);
 288   if (now) adns__timeouts(ads, 1, 0,0, *now);
 289   adns__consistency(ads,0,cc_entex);
 290 }
 291
 292 /* fd handling functions.  These are the top-level of the real work of
 293  * reception and often transmission.
 294  */
 295
 296 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
 297   /* Returns the number of entries filled in.  Always zeroes revents. */
 298
 299   assert(MAX_POLLFDS==2);
 300
 301   pollfds_buf[0].fd= ads->udpsocket;
 302   pollfds_buf[0].events= POLLIN;
 303   pollfds_buf[0].revents= 0;
 304
 305   switch (ads->tcpstate) {
 306   case server_disconnected:
 307     return 1;
 308   case server_connecting:
 309     pollfds_buf[1].events= POLLOUT;
 310     break;
 311   case server_ok:
 312     pollfds_buf[1].events= ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI;
 313     break;
 314   default:
 315     abort();
 316   }
 317   pollfds_buf[1].fd= ads->tcpsocket;
 318   return 2;
 319 }
 320
 321 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
 322   int want, dgramlen, r, udpaddrlen, serv, old_skip;
 323   byte udpbuf[DNS_MAXUDP];
 324   struct sockaddr_in udpaddr;
 325
 326   adns__consistency(ads,0,cc_entex);
 327
 328   switch (ads->tcpstate) {
 329   case server_disconnected:
 330   case server_connecting:
 331     break;
 332   case server_ok:
 333     if (fd != ads->tcpsocket) break;
 334     assert(!ads->tcprecv_skip);
 335     for (;;) {
 336       if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
 337         dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
 338                    ads->tcprecv.buf[ads->tcprecv_skip+1]);
 339         if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
 340           old_skip= ads->tcprecv_skip;
 341           ads->tcprecv_skip += 2+dgramlen;
 342           adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
 343                           dgramlen, ads->tcpserver, 1,*now);
 344           continue;
 345         } else {
 346           want= 2+dgramlen;
 347         }
 348       } else {
 349         want= 2;
 350       }
 351       ads->tcprecv.used -= ads->tcprecv_skip;
 352       memmove(ads->tcprecv.buf,ads->tcprecv.buf+ads->tcprecv_skip,ads->tcprecv.used);
 353       ads->tcprecv_skip= 0;
 354       if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
 355       assert(ads->tcprecv.used <= ads->tcprecv.avail);
 356       if (ads->tcprecv.used == ads->tcprecv.avail) continue;
 357       r= read(ads->tcpsocket,
 358               ads->tcprecv.buf+ads->tcprecv.used,
 359               ads->tcprecv.avail-ads->tcprecv.used);
 360       if (r>0) {
 361         ads->tcprecv.used+= r;
 362       } else {
 363         if (r) {
 364           if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 365           if (errno==EINTR) continue;
 366           if (errno_resources(errno)) { r= errno; goto xit; }
 367         }
 368         adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
 369         r= 0; goto xit;
 370       }
 371     } /* never reached */
 372   default:
 373     abort();
 374   }
 375   if (fd == ads->udpsocket) {
 376     for (;;) {
 377       udpaddrlen= sizeof(udpaddr);
 378       r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
 379                   (struct sockaddr*)&udpaddr,&udpaddrlen);
 380       if (r<0) {
 381         if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
 382         if (errno == EINTR) continue;
 383         if (errno_resources(errno)) { r= errno; goto xit; }
 384         adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
 385         r= 0; goto xit;
 386       }
 387       if (udpaddrlen != sizeof(udpaddr)) {
 388         adns__diag(ads,-1,0,"datagram received with wrong address length %d"
 389                    " (expected %d)", udpaddrlen,sizeof(udpaddr));
 390         continue;
 391       }
 392       if (udpaddr.sin_family != AF_INET) {
 393         adns__diag(ads,-1,0,"datagram received with wrong protocol family"
 394                    " %u (expected %u)",udpaddr.sin_family,AF_INET);
 395         continue;
 396       }
 397       if (ntohs(udpaddr.sin_port) != DNS_PORT) {
 398         adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
 399                    ntohs(udpaddr.sin_port),DNS_PORT);
 400         continue;
 401       }
 402       for (serv= 0;
 403            serv < ads->nservers &&
 404              ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
 405            serv++);
 406       if (serv >= ads->nservers) {
 407         adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
 408                    inet_ntoa(udpaddr.sin_addr));
 409         continue;
 410       }
 411       adns__procdgram(ads,udpbuf,r,serv,0,*now);
 412     }
 413   }
 414   r= 0;
 415 xit:
 416   adns__consistency(ads,0,cc_entex);
 417   return r;
 418 }
 419
 420 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
 421   int r;
 422
 423   adns__consistency(ads,0,cc_entex);
 424
 425   switch (ads->tcpstate) {
 426   case server_disconnected:
 427     break;
 428   case server_connecting:
 429     if (fd != ads->tcpsocket) break;
 430     assert(ads->tcprecv.used==0);
 431     assert(ads->tcprecv_skip==0);
 432     for (;;) {
 433       if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
 434       r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
 435       if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
 436         tcp_connected(ads,*now);
 437         r= 0; goto xit;
 438       }
 439       if (r>0) {
 440         adns__tcp_broken(ads,"connect/read","sent data before first request");
 441         r= 0; goto xit;
 442       }
 443       if (errno==EINTR) continue;
 444       if (errno_resources(errno)) { r= errno; goto xit; }
 445       adns__tcp_broken(ads,"connect/read",strerror(errno));
 446       r= 0; goto xit;
 447     } /* not reached */
 448   case server_ok:
 449     if (!(ads->tcpsend.used && fd == ads->tcpsocket)) break;
 450     for (;;) {
 451       adns__sigpipe_protect(ads);
 452       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
 453       adns__sigpipe_unprotect(ads);
 454       if (r<0) {
 455         if (errno==EINTR) continue;
 456         if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 457         if (errno_resources(errno)) { r= errno; goto xit; }
 458         adns__tcp_broken(ads,"write",strerror(errno));
 459         r= 0; goto xit;
 460       } else if (r>0) {
 461         ads->tcpsend.used -= r;
 462         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 463       }
 464     } /* not reached */
 465   default:
 466     abort();
 467   }
 468   r= 0;
 469 xit:
 470   adns__consistency(ads,0,cc_entex);
 471   return r;
 472 }
 473
 474 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now) {
 475   adns__consistency(ads,0,cc_entex);
 476   switch (ads->tcpstate) {
 477   case server_disconnected:
 478     break;
 479   case server_connecting:
 480   case server_ok:
 481     if (fd != ads->tcpsocket) break;
 482     adns__tcp_broken(ads,"poll/select","exceptional condition detected");
 483     break;
 484   default:
 485     abort();
 486   }
 487   adns__consistency(ads,0,cc_entex);
 488   return 0;
 489 }
 490
 491 static void fd_event(adns_state ads, int fd,
 492                      int revent, int pollflag,
 493                      int maxfd, const fd_set *fds,
 494                      int (*func)(adns_state, int fd, const struct timeval *now),
 495                      struct timeval now, int *r_r) {
 496   int r;
 497
 498   if (!(revent & pollflag)) return;
 499   if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
 500   r= func(ads,fd,&now);
 501   if (r) {
 502     if (r_r) {
 503       *r_r= r;
 504     } else {
 505       adns__diag(ads,-1,0,"process fd failed after select: %s",strerror(errno));
 506       adns_globalsystemfailure(ads);
 507     }
 508   }
 509 }
 510
 511 void adns__fdevents(adns_state ads,
 512                     const struct pollfd *pollfds, int npollfds,
 513                     int maxfd, const fd_set *readfds,
 514                     const fd_set *writefds, const fd_set *exceptfds,
 515                     struct timeval now, int *r_r) {
 516   int i, fd, revents;
 517
 518   for (i=0; i<npollfds; i++) {
 519     fd= pollfds[i].fd;
 520     if (fd >= maxfd) maxfd= fd+1;
 521     revents= pollfds[i].revents;
 522     fd_event(ads,fd, revents,POLLIN, maxfd,readfds, adns_processreadable,now,r_r);
 523     fd_event(ads,fd, revents,POLLOUT, maxfd,writefds, adns_processwriteable,now,r_r);
 524     fd_event(ads,fd, revents,POLLPRI, maxfd,exceptfds, adns_processexceptional,now,r_r);
 525   }
 526 }
 527
 528 /* Wrappers for select(2). */
 529
 530 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
 531                        fd_set *writefds_io, fd_set *exceptfds_io,
 532                        struct timeval **tv_mod, struct timeval *tv_tobuf,
 533                        const struct timeval *now) {
 534   struct timeval tv_nowbuf;
 535   struct pollfd pollfds[MAX_POLLFDS];
 536   int i, fd, maxfd, npollfds;
 537
 538   adns__consistency(ads,0,cc_entex);
 539
 540   if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
 541     /* The caller is planning to sleep. */
 542     adns__must_gettimeofday(ads,&now,&tv_nowbuf);
 543     if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
 544     adns__timeouts(ads, 1, tv_mod,tv_tobuf, *now);
 545   }
 546
 547   npollfds= adns__pollfds(ads,pollfds);
 548   maxfd= *maxfd_io;
 549   for (i=0; i<npollfds; i++) {
 550     fd= pollfds[i].fd;
 551     if (fd >= maxfd) maxfd= fd+1;
 552     if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
 553     if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
 554     if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
 555   }
 556   *maxfd_io= maxfd;
 557
 558 xit:
 559   adns__consistency(ads,0,cc_entex);
 560 }
 561
 562 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
 563                       const fd_set *writefds, const fd_set *exceptfds,
 564                       const struct timeval *now) {
 565   struct timeval tv_buf;
 566   struct pollfd pollfds[MAX_POLLFDS];
 567   int npollfds, i;
 568
 569   adns__consistency(ads,0,cc_entex);
 570   adns__must_gettimeofday(ads,&now,&tv_buf);
 571   if (!now) goto xit;
 572   adns_processtimeouts(ads,now);
 573
 574   npollfds= adns__pollfds(ads,pollfds);
 575   for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
 576   adns__fdevents(ads,
 577                  pollfds,npollfds,
 578                  maxfd,readfds,writefds,exceptfds,
 579                  *now, 0);
 580 xit:
 581   adns__consistency(ads,0,cc_entex);
 582 }
 583
 584 /* General helpful functions. */
 585
 586 void adns_globalsystemfailure(adns_state ads) {
 587   adns__consistency(ads,0,cc_entex);
 588
 589   while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
 590   while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
 591
 592   switch (ads->tcpstate) {
 593   case server_connecting:
 594   case server_ok:
 595     adns__tcp_broken(ads,0,0);
 596     break;
 597   case server_disconnected:
 598     break;
 599   default:
 600     abort();
 601   }
 602   adns__consistency(ads,0,cc_entex);
 603 }
 604
 605 int adns_processany(adns_state ads) {
 606   int r, i;
 607   struct timeval now;
 608   struct pollfd pollfds[MAX_POLLFDS];
 609   int npollfds;
 610
 611   adns__consistency(ads,0,cc_entex);
 612
 613   r= gettimeofday(&now,0);
 614   if (!r) adns_processtimeouts(ads,&now);
 615
 616   /* We just use adns__fdevents to loop over the fd's trying them.
 617    * This seems more sensible than calling select, since we're most
 618    * likely just to want to do a read on one or two fds anyway.
 619    */
 620   npollfds= adns__pollfds(ads,pollfds);
 621   for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events;
 622   adns__fdevents(ads,
 623                  pollfds,npollfds,
 624                  0,0,0,0,
 625                  now,&r);
 626
 627   adns__consistency(ads,0,cc_entex);
 628   return 0;
 629 }
 630
 631 void adns__autosys(adns_state ads, struct timeval now) {
 632   if (ads->iflags & adns_if_noautosys) return;
 633   adns_processany(ads);
 634 }
 635
 636 int adns__internal_check(adns_state ads,
 637                          adns_query *query_io,
 638                          adns_answer **answer,
 639                          void **context_r) {
 640   adns_query qu;
 641
 642   qu= *query_io;
 643   if (!qu) {
 644     if (ads->output.head) {
 645       qu= ads->output.head;
 646     } else if (ads->udpw.head || ads->tcpw.head) {
 647       return EAGAIN;
 648     } else {
 649       return ESRCH;
 650     }
 651   } else {
 652     if (qu->id>=0) return EAGAIN;
 653   }
 654   LIST_UNLINK(ads->output,qu);
 655   *answer= qu->answer;
 656   if (context_r) *context_r= qu->ctx.ext;
 657   *query_io= qu;
 658   free(qu);
 659   return 0;
 660 }
 661
 662 int adns_wait(adns_state ads,
 663               adns_query *query_io,
 664               adns_answer **answer_r,
 665               void **context_r) {
 666   int r, maxfd, rsel;
 667   fd_set readfds, writefds, exceptfds;
 668   struct timeval tvbuf, *tvp;
 669
 670   adns__consistency(ads,*query_io,cc_entex);
 671   for (;;) {
 672     r= adns__internal_check(ads,query_io,answer_r,context_r);
 673     if (r != EAGAIN) break;
 674     maxfd= 0; tvp= 0;
 675     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 676     ads->bug_if_query_done_now= 1;
 677     adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
 678     ads->bug_if_query_done_now= 0;
 679     assert(tvp);
 680     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 681     if (rsel==-1) {
 682       if (errno == EINTR) {
 683         if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
 684       } else {
 685         adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
 686         adns_globalsystemfailure(ads);
 687       }
 688     } else {
 689       assert(rsel >= 0);
 690       adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
 691     }
 692   }
 693   adns__consistency(ads,0,cc_entex);
 694   return r;
 695 }
 696
 697 int adns_check(adns_state ads,
 698                adns_query *query_io,
 699                adns_answer **answer_r,
 700                void **context_r) {
 701   struct timeval now;
 702   int r;
 703
 704   adns__consistency(ads,*query_io,cc_entex);
 705   r= gettimeofday(&now,0);
 706   if (!r) adns__autosys(ads,now);
 707
 708   r= adns__internal_check(ads,query_io,answer_r,context_r);
 709   adns__consistency(ads,0,cc_entex);
 710   return r;
 711 }