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