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 part of adns, which is
   9  *    Copyright (C) 1997-2000,2003,2006,2014  Ian Jackson
  10  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
  11  *    Copyright (C) 1991 Massachusetts Institute of Technology
  12  *  (See the file INSTALL for full details.)
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License as published by
  16  *  the Free Software Foundation; either version 3, or (at your option)
  17  *  any later version.
  18  *
  19  *  This program is distributed in the hope that it will be useful,
  20  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  *  GNU General Public License for more details.
  23  *
  24  *  You should have received a copy of the GNU General Public License
  25  *  along with this program; if not, write to the Free Software Foundation.
  26  */
  27
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <unistd.h>
  31
  32 #include <sys/types.h>
  33 #include <sys/time.h>
  34 #include <netdb.h>
  35 #include <sys/socket.h>
  36 #include <netinet/in.h>
  37 #include <arpa/inet.h>
  38
  39 #include "internal.h"
  40 #include "tvarith.h"
  41
  42 /* TCP connection management. */
  43
  44 static void tcp_close(adns_state ads) {
  45   close(ads->tcpsocket);
  46   ads->tcpsocket= -1;
  47   ads->tcprecv.used= ads->tcprecv_skip= ads->tcpsend.used= 0;
  48 }
  49
  50 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
  51   int serv;
  52   adns_query qu;
  53
  54   assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
  55   serv= ads->tcpserver;
  56   if (what) adns__warn(ads,serv,0,"TCP connection failed: %s: %s",what,why);
  57
  58   if (ads->tcpstate == server_connecting) {
  59     /* Counts as a retry for all the queries waiting for TCP. */
  60     for (qu= ads->tcpw.head; qu; qu= qu->next)
  61       qu->retries++;
  62   }
  63
  64   tcp_close(ads);
  65   ads->tcpstate= server_broken;
  66   ads->tcpserver= (serv+1)%ads->nservers;
  67 }
  68
  69 static void tcp_connected(adns_state ads, struct timeval now) {
  70   adns_query qu, nqu;
  71
  72   adns__debug(ads,ads->tcpserver,0,"TCP connected");
  73   ads->tcpstate= server_ok;
  74   for (qu= ads->tcpw.head; qu && ads->tcpstate == server_ok; qu= nqu) {
  75     nqu= qu->next;
  76     assert(qu->state == query_tcpw);
  77     adns__querysend_tcp(qu,now);
  78   }
  79 }
  80
  81 static void tcp_broken_events(adns_state ads) {
  82   adns_query qu, nqu;
  83
  84   assert(ads->tcpstate == server_broken);
  85   for (qu= ads->tcpw.head; qu; qu= nqu) {
  86     nqu= qu->next;
  87     assert(qu->state == query_tcpw);
  88     if (qu->retries > ads->nservers) {
  89       LIST_UNLINK(ads->tcpw,qu);
  90       adns__query_fail(qu,adns_s_allservfail);
  91     }
  92   }
  93   ads->tcpstate= server_disconnected;
  94 }
  95
  96 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
  97   int r, fd, tries;
  98   adns_rr_addr *addr;
  99   struct protoent *proto;
 100
 101   for (tries=0; tries<ads->nservers; tries++) {
 102     switch (ads->tcpstate) {
 103     case server_connecting:
 104     case server_ok:
 105     case server_broken:
 106       return;
 107     case server_disconnected:
 108       break;
 109     default:
 110       abort();
 111     }
 112
 113     assert(!ads->tcpsend.used);
 114     assert(!ads->tcprecv.used);
 115     assert(!ads->tcprecv_skip);
 116
 117     proto= getprotobyname("tcp");
 118     if (!proto) {
 119       adns__diag(ads,-1,0,"unable to find protocol no. for TCP !");
 120       return;
 121     }
 122     addr = &ads->servers[ads->tcpserver];
 123     fd= socket(addr->addr.sa.sa_family, SOCK_STREAM, proto->p_proto);
 124     if (fd<0) {
 125       adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
 126       return;
 127     }
 128     r= adns__setnonblock(ads,fd);
 129     if (r) {
 130       adns__diag(ads,-1,0,"cannot make TCP socket nonblocking:"
 131                  " %s",strerror(r));
 132       close(fd);
 133       return;
 134     }
 135     r= connect(fd,&addr->addr.sa,addr->len);
 136     ads->tcpsocket= fd;
 137     ads->tcpstate= server_connecting;
 138     if (r==0) { tcp_connected(ads,now); return; }
 139     if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
 140       ads->tcptimeout= now;
 141       timevaladd(&ads->tcptimeout,TCPCONNMS);
 142       return;
 143     }
 144     adns__tcp_broken(ads,"connect",strerror(errno));
 145     tcp_broken_events(ads);
 146   }
 147 }
 148
 149 /* Timeout handling functions. */
 150
 151 void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io,
 152                              struct timeval *tv_buf) {
 153   const struct timeval *now;
 154   int r;
 155
 156   now= *now_io;
 157   if (now) return;
 158   r= gettimeofday(tv_buf,0); if (!r) { *now_io= tv_buf; return; }
 159   adns__diag(ads,-1,0,"gettimeofday failed: %s",strerror(errno));
 160   adns_globalsystemfailure(ads);
 161   return;
 162 }
 163
 164 static void inter_immed(struct timeval **tv_io, struct timeval *tvbuf) {
 165   struct timeval *rbuf;
 166
 167   if (!tv_io) return;
 168
 169   rbuf= *tv_io;
 170   if (!rbuf) { *tv_io= rbuf= tvbuf; }
 171
 172   timerclear(rbuf);
 173 }
 174
 175 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
 176                         struct timeval maxto) {
 177   struct timeval *rbuf;
 178
 179   if (!tv_io) return;
 180   rbuf= *tv_io;
 181   if (!rbuf) {
 182     *tvbuf= maxto; *tv_io= tvbuf;
 183   } else {
 184     if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 185   }
 186 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
 187         maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
 188 }
 189
 190 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 191                            struct timeval now, struct timeval maxtime) {
 192   /* tv_io may be 0 */
 193   ldiv_t dr;
 194
 195 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
 196         now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
 197   if (!tv_io) return;
 198   maxtime.tv_sec -= (now.tv_sec+2);
 199   maxtime.tv_usec -= (now.tv_usec-2000000);
 200   dr= ldiv(maxtime.tv_usec,1000000);
 201   maxtime.tv_sec += dr.quot;
 202   maxtime.tv_usec -= dr.quot*1000000;
 203   if (maxtime.tv_sec<0) timerclear(&maxtime);
 204   inter_maxto(tv_io,tvbuf,maxtime);
 205 }
 206
 207 static void timeouts_queue(adns_state ads, int act,
 208                            struct timeval **tv_io, struct timeval *tvbuf,
 209                            struct timeval now, struct query_queue *queue) {
 210   adns_query qu, nqu;
 211
 212   for (qu= queue->head; qu; qu= nqu) {
 213     nqu= qu->next;
 214     if (!timercmp(&now,&qu->timeout,>)) {
 215       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 216     } else {
 217       if (!act) { inter_immed(tv_io,tvbuf); return; }
 218       LIST_UNLINK(*queue,qu);
 219       if (qu->state != query_tosend) {
 220         adns__query_fail(qu,adns_s_timeout);
 221       } else {
 222         adns__query_send(qu,now);
 223       }
 224       nqu= queue->head;
 225     }
 226   }
 227 }
 228
 229 static void tcp_events(adns_state ads, int act,
 230                        struct timeval **tv_io, struct timeval *tvbuf,
 231                        struct timeval now) {
 232   for (;;) {
 233     switch (ads->tcpstate) {
 234     case server_broken:
 235       if (!act) { inter_immed(tv_io,tvbuf); return; }
 236       tcp_broken_events(ads);
 237     case server_disconnected: /* fall through */
 238       if (!ads->tcpw.head) return;
 239       if (!act) { inter_immed(tv_io,tvbuf); return; }
 240       adns__tcp_tryconnect(ads,now);
 241       break;
 242     case server_ok:
 243       if (ads->tcpw.head) return;
 244       if (!ads->tcptimeout.tv_sec) {
 245         assert(!ads->tcptimeout.tv_usec);
 246         ads->tcptimeout= now;
 247         timevaladd(&ads->tcptimeout,TCPIDLEMS);
 248       }
 249     case server_connecting: /* fall through */
 250       if (!act || !timercmp(&now,&ads->tcptimeout,>)) {
 251         inter_maxtoabs(tv_io,tvbuf,now,ads->tcptimeout);
 252         return;
 253       } {
 254         /* TCP timeout has happened */
 255         switch (ads->tcpstate) {
 256         case server_connecting: /* failed to connect */
 257           adns__tcp_broken(ads,"unable to make connection","timed out");
 258           break;
 259         case server_ok: /* idle timeout */
 260           tcp_close(ads);
 261           ads->tcpstate= server_disconnected;
 262           return;
 263         default:
 264           abort();
 265         }
 266       }
 267       break;
 268     default:
 269       abort();
 270     }
 271   }
 272   return;
 273 }
 274
 275 void adns__timeouts(adns_state ads, int act,
 276                     struct timeval **tv_io, struct timeval *tvbuf,
 277                     struct timeval now) {
 278   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->udpw);
 279   timeouts_queue(ads,act,tv_io,tvbuf,now, &ads->tcpw);
 280   tcp_events(ads,act,tv_io,tvbuf,now);
 281 }
 282
 283 void adns_firsttimeout(adns_state ads,
 284                        struct timeval **tv_io, struct timeval *tvbuf,
 285                        struct timeval now) {
 286   adns__consistency(ads,0,cc_entex);
 287   adns__timeouts(ads, 0, tv_io,tvbuf, now);
 288   adns__returning(ads,0);
 289 }
 290
 291 void adns_processtimeouts(adns_state ads, const struct timeval *now) {
 292   struct timeval tv_buf;
 293
 294   adns__consistency(ads,0,cc_entex);
 295   adns__must_gettimeofday(ads,&now,&tv_buf);
 296   if (now) adns__timeouts(ads, 1, 0,0, *now);
 297   adns__returning(ads,0);
 298 }
 299
 300 /* fd handling functions.  These are the top-level of the real work of
 301  * reception and often transmission.
 302  */
 303
 304 int adns__pollfds(adns_state ads, struct pollfd pollfds_buf[MAX_POLLFDS]) {
 305   /* Returns the number of entries filled in.  Always zeroes revents. */
 306   int nwanted=0;
 307 #define ADD_POLLFD(wantfd, wantevents) do{      \
 308     pollfds_buf[nwanted].fd= (wantfd);          \
 309     pollfds_buf[nwanted].events= (wantevents);  \
 310     pollfds_buf[nwanted].revents= 0;            \
 311     nwanted++;                                  \
 312   }while(0)
 313
 314   int i;
 315
 316   assert(MAX_POLLFDS == MAXUDP + 1);
 317
 318   for (i=0; i<ads->nudpsockets; i++)
 319     ADD_POLLFD(ads->udpsockets[i].fd, POLLIN);
 320
 321   switch (ads->tcpstate) {
 322   case server_disconnected:
 323   case server_broken:
 324     break;
 325   case server_connecting:
 326     ADD_POLLFD(ads->tcpsocket, POLLOUT);
 327     break;
 328   case server_ok:
 329     ADD_POLLFD(ads->tcpsocket,
 330                ads->tcpsend.used ? POLLIN|POLLOUT|POLLPRI : POLLIN|POLLPRI);
 331     break;
 332   default:
 333     abort();
 334   }
 335   assert(nwanted<=MAX_POLLFDS);
 336 #undef ADD_POLLFD
 337   return nwanted;
 338 }
 339
 340 int adns_processreadable(adns_state ads, int fd, const struct timeval *now) {
 341   int want, dgramlen, r, i, udpaddrlen, serv, old_skip;
 342   byte udpbuf[DNS_MAXUDP];
 343   char addrbuf[ADNS_ADDR2TEXT_BUFLEN];
 344   struct udpsocket *udp;
 345   adns_sockaddr udpaddr;
 346
 347   adns__consistency(ads,0,cc_entex);
 348
 349   switch (ads->tcpstate) {
 350   case server_disconnected:
 351   case server_broken:
 352   case server_connecting:
 353     break;
 354   case server_ok:
 355     if (fd != ads->tcpsocket) break;
 356     assert(!ads->tcprecv_skip);
 357     do {
 358       if (ads->tcprecv.used >= ads->tcprecv_skip+2) {
 359         dgramlen= ((ads->tcprecv.buf[ads->tcprecv_skip]<<8) |
 360                    ads->tcprecv.buf[ads->tcprecv_skip+1]);
 361         if (ads->tcprecv.used >= ads->tcprecv_skip+2+dgramlen) {
 362           old_skip= ads->tcprecv_skip;
 363           ads->tcprecv_skip += 2+dgramlen;
 364           adns__procdgram(ads, ads->tcprecv.buf+old_skip+2,
 365                           dgramlen, ads->tcpserver, 1,*now);
 366           continue;
 367         } else {
 368           want= 2+dgramlen;
 369         }
 370       } else {
 371         want= 2;
 372       }
 373       ads->tcprecv.used -= ads->tcprecv_skip;
 374       memmove(ads->tcprecv.buf, ads->tcprecv.buf+ads->tcprecv_skip,
 375               ads->tcprecv.used);
 376       ads->tcprecv_skip= 0;
 377       if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
 378       assert(ads->tcprecv.used <= ads->tcprecv.avail);
 379       if (ads->tcprecv.used == ads->tcprecv.avail) continue;
 380       r= read(ads->tcpsocket,
 381               ads->tcprecv.buf+ads->tcprecv.used,
 382               ads->tcprecv.avail-ads->tcprecv.used);
 383       if (r>0) {
 384         ads->tcprecv.used+= r;
 385       } else {
 386         if (r) {
 387           if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 388           if (errno==EINTR) continue;
 389           if (errno_resources(errno)) { r= errno; goto xit; }
 390         }
 391         adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
 392       }
 393     } while (ads->tcpstate == server_ok);
 394     r= 0; goto xit;
 395   default:
 396     abort();
 397   }
 398   for (i=0; i<ads->nudpsockets; i++) {
 399     udp= &ads->udpsockets[i];
 400     if (fd != udp->fd) continue;
 401     for (;;) {
 402       udpaddrlen= sizeof(udpaddr);
 403       r= recvfrom(fd,udpbuf,sizeof(udpbuf),0, &udpaddr.sa,&udpaddrlen);
 404       if (r<0) {
 405         if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
 406         if (errno == EINTR) continue;
 407         if (errno_resources(errno)) { r= errno; goto xit; }
 408         adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
 409         r= 0; goto xit;
 410       }
 411       for (serv= 0;
 412            serv < ads->nservers &&
 413              !adns__sockaddrs_equal(&udpaddr.sa,
 414                                     &ads->servers[serv].addr.sa);
 415            serv++);
 416       if (serv >= ads->nservers) {
 417         adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
 418                    adns__sockaddr_ntoa(&udpaddr.sa, addrbuf));
 419         continue;
 420       }
 421       adns__procdgram(ads,udpbuf,r,serv,0,*now);
 422     }
 423     break;
 424   }
 425   r= 0;
 426 xit:
 427   adns__returning(ads,0);
 428   return r;
 429 }
 430
 431 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
 432   int r;
 433
 434   adns__consistency(ads,0,cc_entex);
 435
 436   switch (ads->tcpstate) {
 437   case server_disconnected:
 438   case server_broken:
 439     break;
 440   case server_connecting:
 441     if (fd != ads->tcpsocket) break;
 442     assert(ads->tcprecv.used==0);
 443     assert(ads->tcprecv_skip==0);
 444     for (;;) {
 445       if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
 446       r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
 447       if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
 448         tcp_connected(ads,*now);
 449         r= 0; goto xit;
 450       }
 451       if (r>0) {
 452         adns__tcp_broken(ads,"connect/read","sent data before first request");
 453         r= 0; goto xit;
 454       }
 455       if (errno==EINTR) continue;
 456       if (errno_resources(errno)) { r= errno; goto xit; }
 457       adns__tcp_broken(ads,"connect/read",strerror(errno));
 458       r= 0; goto xit;
 459     } /* not reached */
 460   case server_ok:
 461     if (fd != ads->tcpsocket) break;
 462     while (ads->tcpsend.used) {
 463       adns__sigpipe_protect(ads);
 464       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
 465       adns__sigpipe_unprotect(ads);
 466       if (r<0) {
 467         if (errno==EINTR) continue;
 468         if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
 469         if (errno_resources(errno)) { r= errno; goto xit; }
 470         adns__tcp_broken(ads,"write",strerror(errno));
 471         r= 0; goto xit;
 472       } else if (r>0) {
 473         ads->tcpsend.used -= r;
 474         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 475       }
 476     }
 477     r= 0;
 478     goto xit;
 479   default:
 480     abort();
 481   }
 482   r= 0;
 483 xit:
 484   adns__returning(ads,0);
 485   return r;
 486 }
 487
 488 int adns_processexceptional(adns_state ads, int fd,
 489                             const struct timeval *now) {
 490   adns__consistency(ads,0,cc_entex);
 491   switch (ads->tcpstate) {
 492   case server_disconnected:
 493   case server_broken:
 494     break;
 495   case server_connecting:
 496   case server_ok:
 497     if (fd != ads->tcpsocket) break;
 498     adns__tcp_broken(ads,"poll/select","exceptional condition detected");
 499     break;
 500   default:
 501     abort();
 502   }
 503   adns__returning(ads,0);
 504   return 0;
 505 }
 506
 507 static void fd_event(adns_state ads, int fd,
 508                      int revent, int pollflag,
 509                      int maxfd, const fd_set *fds,
 510                      int (*func)(adns_state, int fd,
 511                                  const struct timeval *now),
 512                      struct timeval now, int *r_r) {
 513   int r;
 514
 515   if (!(revent & pollflag)) return;
 516   if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
 517   r= func(ads,fd,&now);
 518   if (r) {
 519     if (r_r) {
 520       *r_r= r;
 521     } else {
 522       adns__diag(ads,-1,0,"process fd failed after select:"
 523                  " %s",strerror(errno));
 524       adns_globalsystemfailure(ads);
 525     }
 526   }
 527 }
 528
 529 void adns__fdevents(adns_state ads,
 530                     const struct pollfd *pollfds, int npollfds,
 531                     int maxfd, const fd_set *readfds,
 532                     const fd_set *writefds, const fd_set *exceptfds,
 533                     struct timeval now, int *r_r) {
 534   int i, fd, revents;
 535
 536   for (i=0; i<npollfds; i++) {
 537     fd= pollfds[i].fd;
 538     if (fd >= maxfd) maxfd= fd+1;
 539     revents= pollfds[i].revents;
 540 #define EV(pollfl,fds,how)  \
 541     fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
 542     EV( POLLIN,  readfds,   readable    );
 543     EV( POLLOUT, writefds,  writeable   );
 544     EV( POLLPRI, exceptfds, exceptional );
 545 #undef EV
 546   }
 547 }
 548
 549 /* Wrappers for select(2). */
 550
 551 void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
 552                        fd_set *writefds_io, fd_set *exceptfds_io,
 553                        struct timeval **tv_mod, struct timeval *tv_tobuf,
 554                        const struct timeval *now) {
 555   struct timeval tv_nowbuf;
 556   struct pollfd pollfds[MAX_POLLFDS];
 557   int i, fd, maxfd, npollfds;
 558
 559   adns__consistency(ads,0,cc_entex);
 560
 561   if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
 562     /* The caller is planning to sleep. */
 563     adns__must_gettimeofday(ads,&now,&tv_nowbuf);
 564     if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
 565     adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
 566   }
 567
 568   npollfds= adns__pollfds(ads,pollfds);
 569   maxfd= *maxfd_io;
 570   for (i=0; i<npollfds; i++) {
 571     fd= pollfds[i].fd;
 572     if (fd >= maxfd) maxfd= fd+1;
 573     if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
 574     if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
 575     if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
 576   }
 577   *maxfd_io= maxfd;
 578
 579 xit:
 580   adns__returning(ads,0);
 581 }
 582
 583 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
 584                       const fd_set *writefds, const fd_set *exceptfds,
 585                       const struct timeval *now) {
 586   struct timeval tv_buf;
 587   struct pollfd pollfds[MAX_POLLFDS];
 588   int npollfds, i;
 589
 590   adns__consistency(ads,0,cc_entex);
 591   adns__must_gettimeofday(ads,&now,&tv_buf);
 592   if (!now) goto xit;
 593   adns_processtimeouts(ads,now);
 594
 595   npollfds= adns__pollfds(ads,pollfds);
 596   for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
 597   adns__fdevents(ads,
 598                  pollfds,npollfds,
 599                  maxfd,readfds,writefds,exceptfds,
 600                  *now, 0);
 601 xit:
 602   adns__returning(ads,0);
 603 }
 604
 605 /* General helpful functions. */
 606
 607 void adns_globalsystemfailure(adns_state ads) {
 608   adns__consistency(ads,0,cc_entex);
 609
 610   while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
 611   while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
 612
 613   switch (ads->tcpstate) {
 614   case server_connecting:
 615   case server_ok:
 616     adns__tcp_broken(ads,0,0);
 617     break;
 618   case server_disconnected:
 619   case server_broken:
 620     break;
 621   default:
 622     abort();
 623   }
 624   adns__returning(ads,0);
 625 }
 626
 627 int adns_processany(adns_state ads) {
 628   int r, i;
 629   struct timeval now;
 630   struct pollfd pollfds[MAX_POLLFDS];
 631   int npollfds;
 632
 633   adns__consistency(ads,0,cc_entex);
 634
 635   r= gettimeofday(&now,0);
 636   if (!r) adns_processtimeouts(ads,&now);
 637
 638   /* We just use adns__fdevents to loop over the fd's trying them.
 639    * This seems more sensible than calling select, since we're most
 640    * likely just to want to do a read on one or two fds anyway.
 641    */
 642   npollfds= adns__pollfds(ads,pollfds);
 643   for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
 644   adns__fdevents(ads,
 645                  pollfds,npollfds,
 646                  0,0,0,0,
 647                  now,&r);
 648
 649   adns__returning(ads,0);
 650   return 0;
 651 }
 652
 653 void adns__autosys(adns_state ads, struct timeval now) {
 654   if (ads->iflags & adns_if_noautosys) return;
 655   adns_processany(ads);
 656 }
 657
 658 int adns__internal_check(adns_state ads,
 659                          adns_query *query_io,
 660                          adns_answer **answer,
 661                          void **context_r) {
 662   adns_query qu;
 663
 664   qu= *query_io;
 665   if (!qu) {
 666     if (ads->output.head) {
 667       qu= ads->output.head;
 668     } else if (ads->udpw.head || ads->tcpw.head) {
 669       return EAGAIN;
 670     } else {
 671       return ESRCH;
 672     }
 673   } else {
 674     if (qu->id>=0) return EAGAIN;
 675   }
 676   LIST_UNLINK(ads->output,qu);
 677   *answer= qu->answer;
 678   if (context_r) *context_r= qu->ctx.ext;
 679   *query_io= qu;
 680   free(qu);
 681   return 0;
 682 }
 683
 684 int adns_wait(adns_state ads,
 685               adns_query *query_io,
 686               adns_answer **answer_r,
 687               void **context_r) {
 688   int r, maxfd, rsel;
 689   fd_set readfds, writefds, exceptfds;
 690   struct timeval tvbuf, *tvp;
 691
 692   adns__consistency(ads,*query_io,cc_entex);
 693   for (;;) {
 694     r= adns__internal_check(ads,query_io,answer_r,context_r);
 695     if (r != EAGAIN) break;
 696     maxfd= 0; tvp= 0;
 697     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 698     adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
 699     assert(tvp);
 700     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 701     if (rsel==-1) {
 702       if (errno == EINTR) {
 703         if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
 704       } else {
 705         adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
 706         adns_globalsystemfailure(ads);
 707       }
 708     } else {
 709       assert(rsel >= 0);
 710       adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
 711     }
 712   }
 713   adns__returning(ads,0);
 714   return r;
 715 }
 716
 717 int adns_check(adns_state ads,
 718                adns_query *query_io,
 719                adns_answer **answer_r,
 720                void **context_r) {
 721   struct timeval now;
 722   int r;
 723
 724   adns__consistency(ads,*query_io,cc_entex);
 725   r= gettimeofday(&now,0);
 726   if (!r) adns__autosys(ads,now);
 727
 728   r= adns__internal_check(ads,query_io,answer_r,context_r);
 729   adns__returning(ads,0);
 730   return r;
 731 }