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 Copyright (C) 1997-1999 Ian Jackson
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2, or (at your option)
  13  *  any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License
  21  *  along with this program; if not, write to the Free Software Foundation,
  22  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  23  */
  24
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <stdlib.h>
  28
  29 #include <netdb.h>
  30 #include <arpa/inet.h>
  31
  32 #include "internal.h"
  33
  34 /* TCP connection management */
  35
  36 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
  37   int serv;
  38   adns_query qu, nqu;
  39
  40   assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
  41   serv= ads->tcpserver;
  42   adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why);
  43   close(ads->tcpsocket);
  44   ads->tcpstate= server_disconnected;
  45
  46   for (qu= ads->timew.head; qu; qu= nqu) {
  47     nqu= qu->next;
  48     if (qu->state == query_udp) continue;
  49     assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
  50     qu->state= query_tcpwait;
  51     qu->tcpfailed |= (1<<serv);
  52     if (qu->tcpfailed == (1<<ads->nservers)-1) {
  53       LIST_UNLINK(ads->timew,qu);
  54       adns__query_fail(qu,adns_s_allservfail);
  55     }
  56   }
  57
  58   ads->tcprecv.used= ads->tcpsend.used= 0;
  59   ads->tcpserver= (serv+1)%ads->nservers;
  60 }
  61
  62 static void tcp_connected(adns_state ads, struct timeval now) {
  63   adns_query qu, nqu;
  64
  65   adns__debug(ads,ads->tcpserver,0,"TCP connected");
  66   ads->tcpstate= server_ok;
  67   for (qu= ads->timew.head; qu; qu= nqu) {
  68     nqu= qu->next;
  69     if (qu->state == query_udp) continue;
  70     assert (qu->state == query_tcpwait);
  71     adns__query_tcp(qu,now);
  72   }
  73 }
  74
  75 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
  76   int r, fd, tries;
  77   struct sockaddr_in addr;
  78   struct protoent *proto;
  79
  80   for (tries=0; tries<ads->nservers; tries++) {
  81     if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
  82     assert(ads->tcpstate == server_disconnected);
  83     assert(!ads->tcpsend.used);
  84     assert(!ads->tcprecv.used);
  85
  86     proto= getprotobyname("tcp");
  87     if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
  88     fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
  89     if (fd<0) {
  90       adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
  91       return;
  92     }
  93     r= adns__setnonblock(ads,fd);
  94     if (r) {
  95       adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
  96       close(fd);
  97       return;
  98     }
  99     memset(&addr,0,sizeof(addr));
 100     addr.sin_family= AF_INET;
 101     addr.sin_port= htons(DNS_PORT);
 102     addr.sin_addr= ads->servers[ads->tcpserver].addr;
 103     r= connect(fd,&addr,sizeof(addr));
 104     ads->tcpsocket= fd;
 105     ads->tcpstate= server_connecting;
 106     if (r==0) { tcp_connected(ads,now); continue; }
 107     if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
 108     adns__tcp_broken(ads,"connect",strerror(errno));
 109   }
 110 }
 111
 112 /* `Interest' functions - find out which fd's we might be interested in,
 113  * and when we want to be called back for a timeout.
 114  */
 115
 116 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
 117                         struct timeval maxto) {
 118   struct timeval *rbuf;
 119
 120   if (!tv_io) return;
 121   rbuf= *tv_io;
 122   if (!rbuf) {
 123     *tvbuf= maxto; *tv_io= tvbuf;
 124   } else {
 125     if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 126   }
 127 /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
 128         maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);*/
 129 }
 130
 131 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 132                            struct timeval now, struct timeval maxtime) {
 133   ldiv_t dr;
 134
 135 /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
 136         now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);*/
 137   if (!tv_io) return;
 138   maxtime.tv_sec -= (now.tv_sec+2);
 139   maxtime.tv_usec -= (now.tv_usec-2000000);
 140   dr= ldiv(maxtime.tv_usec,1000000);
 141   maxtime.tv_sec += dr.quot;
 142   maxtime.tv_usec -= dr.quot*1000000;
 143   if (maxtime.tv_sec<0) timerclear(&maxtime);
 144   inter_maxto(tv_io,tvbuf,maxtime);
 145 }
 146
 147 static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
 148   if (!maxfd || !fds) return;
 149   if (fd>=*maxfd) *maxfd= fd+1;
 150   FD_SET(fd,fds);
 151 }
 152
 153 static void checktimeouts(adns_state ads, struct timeval now,
 154                           struct timeval **tv_io, struct timeval *tvbuf) {
 155   adns_query qu, nqu;
 156
 157   for (qu= ads->timew.head; qu; qu= nqu) {
 158     nqu= qu->next;
 159     if (timercmp(&now,&qu->timeout,>)) {
 160       LIST_UNLINK(ads->timew,qu);
 161       if (qu->state != query_udp) {
 162         adns__query_fail(qu,adns_s_timeout);
 163       } else {
 164         adns__query_udp(qu,now);
 165       }
 166     } else {
 167       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 168     }
 169   }
 170 }
 171
 172 static void checkfds(adns_state ads, int *maxfd,
 173                      fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 174                      int avail, struct pollfd *buf, int *count_r) {
 175   int count;
 176
 177   count= 0;
 178   inter_addfd(ads->udpsocket,maxfd,readfds);
 179   poll_addfd(ads->udpsocket,avail,buf,&count,POLLIN);
 180
 181   switch (ads->tcpstate) {
 182   case server_disconnected:
 183     break;
 184   case server_connecting:
 185     inter_addfd(ads->tcpsocket,maxfd,writefds);
 186     poll_addfd(ads->tcpsocket,avail,buf,&count,POLLOUT);
 187     break;
 188   case server_ok:
 189     inter_addfd(ads->tcpsocket,maxfd,readfds);
 190     inter_addfd(ads->tcpsocket,maxfd,exceptfds);
 191     if (ads->tcpsend.used) inter_addfd(ads->tcpsocket,maxfd,writefds);
 192     poll_addfd(ads->tcpsocket,avail,buf,&count,
 193                ads->tcpsend.used ? POLLIN|POLLOUT : POLLIN);
 194     break;
 195   default:
 196     abort();
 197   }
 198 }
 199
 200 struct pollfd *adns_pollfds(adns_state ads, struct pollfd *buf,
 201                             int *len_io, int *timeout_io) {
 202   struct timeval now, tvbuf, *tvp;
 203   int timeout;
 204
 205   r= gettimeofday(&now,0);
 206   if (r) return 0;
 207
 208   timeout= *timeout_io;
 209   if (timeout < 0) {
 210     tvtop= 0;
 211   } else {
 212     tvbuf.tv_sec= now.tv_sec + (timeout/1000);
 213     tvbuf.tv_usec= now.tv_usec + (timeout%1000)*1000;
 214     if (tvbuf.tv_sec >= 1000000) {
 215       tvbuf.tv_sec += 1;
 216       tvbuf.tv_usec -= 1000000;
 217     }
 218     tvp= &tvbuf;
 219   }
 220   checktimouts(ads,now,&tvp,&tvbuf);
 221
 222   if (tvp) {
 223     assert(tvbuf.tv_sec<INT_MAX/1000);
 224     *timeout_io= (tvp->tv_sec - now.tv_sec)*1000 + (tvp->tv_usec - now.tv_usec)/1000;
 225   } else {
 226     *timeout_io= -1;
 227   }
 228
 229   avail= *len_io;
 230   if (avail == -1) {
 231     buf= ads->pollfdsbuf;
 232     avail= 2;
 233     if (!buf) {
 234       buf= ads->pollfdsbuf= malloc(sizeof(struct pollfd)*avail);
 235       if (!buf) return 0;
 236     }
 237   }
 238   checkfds(ads, 0,0,0,0, avail,buf,len_io);
 239   if (*len_io > avail) { errno= ENOSPC; return 0; }
 240
 241   return buf;
 242 }
 243
 244 void adns_interest(adns_state ads, int *maxfd,
 245                    fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 246                    struct timeval **tv_io, struct timeval *tvbuf) {
 247   struct timeval now;
 248   struct timeval tvto_lr;
 249   int r;
 250
 251 /*fprintf(stderr,"adns_interest\n");*/
 252
 253   r= gettimeofday(&now,0);
 254   if (r) {
 255     adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s",
 256                strerror(errno));
 257     timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
 258     inter_maxto(tv_io, tvbuf, tvto_lr);
 259   } else {
 260     checktimeouts(ads,now,tv_io,tvbuf);
 261   }
 262
 263   checkfds(ads, maxfd,readfds,writefds,exceptfds, 0,0,0);
 264 }
 265
 266 /* Callback procedures - these do the real work of reception and timeout, etc. */
 267
 268 static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
 269   return maxfd<0 || !fds ? 1 :
 270          fd<maxfd && FD_ISSET(fd,fds);
 271 }
 272
 273 static int internal_callback(adns_state ads, int maxfd,
 274                              const fd_set *readfds, const fd_set *writefds,
 275                              const fd_set *exceptfds,
 276                              struct timeval now) {
 277   int skip, want, dgramlen, count, udpaddrlen, r, serv;
 278   byte udpbuf[DNS_MAXUDP];
 279   struct sockaddr_in udpaddr;
 280
 281   count= 0;
 282
 283   switch (ads->tcpstate) {
 284   case server_disconnected:
 285     break;
 286   case server_connecting:
 287     if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
 288       count++;
 289       assert(ads->tcprecv.used==0);
 290       if (!adns__vbuf_ensure(&ads->tcprecv,1)) return -1;
 291       if (ads->tcprecv.buf) {
 292         r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
 293         if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
 294           tcp_connected(ads,now);
 295         } else if (r>0) {
 296           adns__tcp_broken(ads,"connect/read","sent data before first request");
 297         } else if (errno!=EINTR) {
 298           adns__tcp_broken(ads,"connect/read",strerror(errno));
 299         }
 300       }
 301     }
 302     break;
 303   case server_ok:
 304     count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
 305             callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
 306       (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
 307     if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
 308       skip= 0;
 309       for (;;) {
 310         if (ads->tcprecv.used<skip+2) {
 311           want= 2;
 312         } else {
 313           dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
 314           if (ads->tcprecv.used<skip+2+dgramlen) {
 315             want= 2+dgramlen;
 316           } else {
 317             adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now);
 318             skip+= 2+dgramlen; continue;
 319           }
 320         }
 321         ads->tcprecv.used -= skip;
 322         memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
 323         skip= 0;
 324         if (!adns__vbuf_ensure(&ads->tcprecv,want)) return -1;
 325         assert(ads->tcprecv.used <= ads->tcprecv.avail);
 326         if (ads->tcprecv.used == ads->tcprecv.avail) continue;
 327         r= read(ads->tcpsocket,
 328                 ads->tcprecv.buf+ads->tcprecv.used,
 329                 ads->tcprecv.avail-ads->tcprecv.used);
 330         if (r>0) {
 331           ads->tcprecv.used+= r;
 332         } else {
 333           if (r<0) {
 334             if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
 335             if (errno==EINTR) continue;
 336           }
 337           adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
 338           break;
 339         }
 340       }
 341     } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
 342       adns__tcp_broken(ads,"select","exceptional condition detected");
 343     } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
 344       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
 345       if (r<0) {
 346         if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
 347           adns__tcp_broken(ads,"write",strerror(errno));
 348         }
 349       } else if (r>0) {
 350         ads->tcpsend.used -= r;
 351         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 352       }
 353     }
 354     break;
 355   default:
 356     abort();
 357   }
 358
 359   if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
 360     count++;
 361     for (;;) {
 362       udpaddrlen= sizeof(udpaddr);
 363       r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
 364       if (r<0) {
 365         if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
 366               errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
 367           adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
 368         break;
 369       }
 370       if (udpaddrlen != sizeof(udpaddr)) {
 371         adns__diag(ads,-1,0,"datagram received with wrong address length %d"
 372                    " (expected %d)", udpaddrlen,sizeof(udpaddr));
 373         continue;
 374       }
 375       if (udpaddr.sin_family != AF_INET) {
 376         adns__diag(ads,-1,0,"datagram received with wrong protocol family"
 377                    " %u (expected %u)",udpaddr.sin_family,AF_INET);
 378         continue;
 379       }
 380       if (ntohs(udpaddr.sin_port) != DNS_PORT) {
 381         adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
 382                    ntohs(udpaddr.sin_port),DNS_PORT);
 383         continue;
 384       }
 385       for (serv= 0;
 386            serv < ads->nservers &&
 387              ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
 388            serv++);
 389       if (serv >= ads->nservers) {
 390         adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
 391                    inet_ntoa(udpaddr.sin_addr));
 392         continue;
 393       }
 394       adns__procdgram(ads,udpbuf,r,serv,now);
 395     }
 396   }
 397   return count;
 398 }
 399
 400 int adns_callback(adns_state ads, int maxfd,
 401                   const fd_set *readfds, const fd_set *writefds,
 402                   const fd_set *exceptfds) {
 403   struct timeval now;
 404   int r;
 405
 406   r= gettimeofday(&now,0); if (r) return -1;
 407   checktimeouts(ads,now,0,0);
 408   return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now);
 409 }
 410
 411 /* User-visible functions and their implementation. */
 412
 413 void adns__autosys(adns_state ads, struct timeval now) {
 414   if (ads->iflags & adns_if_noautosys) return;
 415   adns_callback(ads,-1,0,0,0);
 416 }
 417
 418 static int internal_check(adns_state ads,
 419                           adns_query *query_io,
 420                           adns_answer **answer,
 421                           void **context_r) {
 422   adns_query qu;
 423
 424   qu= *query_io;
 425   if (!qu) {
 426     if (!ads->output.head) return EWOULDBLOCK;
 427     qu= ads->output.head;
 428   } else {
 429     if (qu->id>=0) return EWOULDBLOCK;
 430   }
 431   LIST_UNLINK(ads->output,qu);
 432   *answer= qu->answer;
 433   if (context_r) *context_r= qu->ctx.ext;
 434   free(qu);
 435   return 0;
 436 }
 437
 438 int adns_wait(adns_state ads,
 439               adns_query *query_io,
 440               adns_answer **answer_r,
 441               void **context_r) {
 442   int r, maxfd, rsel, rcb;
 443   fd_set readfds, writefds, exceptfds;
 444   struct timeval tvbuf, *tvp;
 445
 446   for (;;) {
 447     r= internal_check(ads,query_io,answer_r,context_r);
 448     if (r != EWOULDBLOCK) return r;
 449     maxfd= 0; tvp= 0;
 450     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 451     adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
 452     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 453     if (rsel==-1) {
 454       if (errno == EINTR && !(ads->iflags & adns_if_eintr)) continue;
 455       return errno;
 456     }
 457     rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
 458     assert(rcb==rsel);
 459   }
 460 }
 461
 462 int adns_check(adns_state ads,
 463                adns_query *query_io,
 464                adns_answer **answer_r,
 465                void **context_r) {
 466   struct timeval now;
 467   int r;
 468
 469   r= gettimeofday(&now,0); if (r) return errno;
 470   adns__autosys(ads,now);
 471   return internal_check(ads,query_io,answer_r,context_r);
 472 }