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

   1 /**/
   2
   3 #include <string.h>
   4 #include <errno.h>
   5 #include <stdlib.h>
   6
   7 #include <netdb.h>
   8 #include <arpa/inet.h>
   9
  10 #include "internal.h"
  11
  12 /* TCP connection management */
  13
  14 void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
  15   int serv;
  16   adns_query qu, nqu;
  17
  18   assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
  19   serv= ads->tcpserver;
  20   adns__warn(ads,serv,0,"TCP connection lost: %s: %s",what,why);
  21   close(ads->tcpsocket);
  22   ads->tcpstate= server_disconnected;
  23
  24   for (qu= ads->timew.head; qu; qu= nqu) {
  25     nqu= qu->next;
  26     if (qu->state == query_udp) continue;
  27     assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
  28     qu->state= query_tcpwait;
  29     qu->tcpfailed |= (1<<serv);
  30     if (qu->tcpfailed == (1<<ads->nservers)-1) {
  31       LIST_UNLINK(ads->timew,qu);
  32       adns__query_fail(ads,qu,adns_s_allservfail);
  33     }
  34   }
  35
  36   ads->tcprecv.used= ads->tcpsend.used= 0;
  37   ads->tcpserver= (serv+1)%ads->nservers;
  38 }
  39
  40 static void tcp_connected(adns_state ads, struct timeval now) {
  41   adns_query qu, nqu;
  42
  43   adns__debug(ads,ads->tcpserver,0,"TCP connected");
  44   ads->tcpstate= server_ok;
  45   for (qu= ads->timew.head; qu; qu= nqu) {
  46     nqu= qu->next;
  47     if (qu->state == query_udp) continue;
  48     assert (qu->state == query_tcpwait);
  49     adns__query_tcp(ads,qu,now);
  50   }
  51 }
  52
  53 void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
  54   int r, fd, tries;
  55   struct sockaddr_in addr;
  56   struct protoent *proto;
  57   /* fixme: single TCP timeout, not once per server */
  58
  59   for (tries=0; tries<ads->nservers; tries++) {
  60     if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
  61     assert(ads->tcpstate == server_disconnected);
  62     assert(!ads->tcpsend.used);
  63     assert(!ads->tcprecv.used);
  64
  65     proto= getprotobyname("tcp");
  66     if (!proto) { adns__diag(ads,-1,0,"unable to find protocol no. for TCP !"); return; }
  67     fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
  68     if (fd<0) {
  69       adns__diag(ads,-1,0,"cannot create TCP socket: %s",strerror(errno));
  70       return;
  71     }
  72     r= adns__setnonblock(ads,fd);
  73     if (r) {
  74       adns__diag(ads,-1,0,"cannot make TCP socket nonblocking: %s",strerror(r));
  75       close(fd);
  76       return;
  77     }
  78     memset(&addr,0,sizeof(addr));
  79     addr.sin_family= AF_INET;
  80     addr.sin_port= htons(DNS_PORT);
  81     addr.sin_addr= ads->servers[ads->tcpserver].addr;
  82     r= connect(fd,&addr,sizeof(addr));
  83     ads->tcpsocket= fd;
  84     ads->tcpstate= server_connecting;
  85     if (r==0) { tcp_connected(ads,now); continue; }
  86     if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
  87     adns__tcp_broken(ads,"connect",strerror(errno));
  88   }
  89 }
  90
  91 /* `Interest' functions - find out which fd's we might be interested in,
  92  * and when we want to be called back for a timeout.
  93  */
  94
  95 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
  96                         struct timeval maxto) {
  97   struct timeval *rbuf;
  98
  99   if (!tv_io) return;
 100   rbuf= *tv_io;
 101   if (!rbuf) {
 102     *tvbuf= maxto; *tv_io= tvbuf;
 103   } else {
 104     if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 105   }
 106 fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
 107         maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec);
 108 }
 109
 110 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 111                            struct timeval now, struct timeval maxtime) {
 112   ldiv_t dr;
 113
 114 fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
 115         now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec);
 116   if (!tv_io) return;
 117   maxtime.tv_sec -= (now.tv_sec+2);
 118   maxtime.tv_usec -= (now.tv_usec-2000000);
 119   dr= ldiv(maxtime.tv_usec,1000000);
 120   maxtime.tv_sec += dr.quot;
 121   maxtime.tv_usec -= dr.quot*1000000;
 122   if (maxtime.tv_sec<0) timerclear(&maxtime);
 123   inter_maxto(tv_io,tvbuf,maxtime);
 124 }
 125
 126 static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
 127   if (!maxfd || !fds) return;
 128   if (fd>=*maxfd) *maxfd= fd+1;
 129   FD_SET(fd,fds);
 130 }
 131
 132 static void checktimeouts(adns_state ads, struct timeval now,
 133                           struct timeval **tv_io, struct timeval *tvbuf) {
 134   adns_query qu, nqu;
 135
 136   for (qu= ads->timew.head; qu; qu= nqu) {
 137     nqu= qu->next;
 138     if (timercmp(&now,&qu->timeout,>)) {
 139       LIST_UNLINK(ads->timew,qu);
 140       if (qu->state != query_udp) {
 141         adns__query_fail(ads,qu,adns_s_timeout);
 142       } else {
 143         adns__query_udp(ads,qu,now);
 144       }
 145     } else {
 146       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 147     }
 148   }
 149 }
 150
 151 void adns_interest(adns_state ads, int *maxfd,
 152                    fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 153                    struct timeval **tv_io, struct timeval *tvbuf) {
 154   struct timeval now;
 155   struct timeval tvto_lr;
 156   int r;
 157
 158 fprintf(stderr,"adns_interest\n");
 159
 160 r= gettimeofday(&now,0);
 161   if (r) {
 162     adns__warn(ads,-1,0,"gettimeofday failed - will sleep for a bit: %s",
 163                strerror(errno));
 164     timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
 165     inter_maxto(tv_io, tvbuf, tvto_lr);
 166   } else {
 167     checktimeouts(ads,now,tv_io,tvbuf);
 168   }
 169
 170   inter_addfd(maxfd,readfds,ads->udpsocket);
 171
 172   switch (ads->tcpstate) {
 173   case server_disconnected:
 174     break;
 175   case server_connecting:
 176     inter_addfd(maxfd,writefds,ads->tcpsocket);
 177     break;
 178   case server_ok:
 179     inter_addfd(maxfd,readfds,ads->tcpsocket);
 180     inter_addfd(maxfd,exceptfds,ads->tcpsocket);
 181     if (ads->tcpsend.used) inter_addfd(maxfd,writefds,ads->tcpsocket);
 182   default:
 183     abort();
 184   }
 185 }
 186
 187 /* Callback procedures - these do the real work of reception and timeout, etc. */
 188
 189 static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
 190   return maxfd<0 || !fds ? 1 :
 191          fd<maxfd && FD_ISSET(fd,fds);
 192 }
 193
 194 static int internal_callback(adns_state ads, int maxfd,
 195                              const fd_set *readfds, const fd_set *writefds,
 196                              const fd_set *exceptfds,
 197                              struct timeval now) {
 198   int skip, want, dgramlen, count, udpaddrlen, r, serv;
 199   byte udpbuf[DNS_MAXUDP];
 200   struct sockaddr_in udpaddr;
 201
 202   count= 0;
 203
 204   switch (ads->tcpstate) {
 205   case server_disconnected:
 206     break;
 207   case server_connecting:
 208     if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
 209       count++;
 210       assert(ads->tcprecv.used==0);
 211       adns__vbuf_ensure(&ads->tcprecv,1);
 212       if (ads->tcprecv.buf) {
 213         r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
 214         if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
 215           tcp_connected(ads,now);
 216         } else if (r>0) {
 217           adns__tcp_broken(ads,"connect/read","sent data before first request");
 218         } else if (errno!=EINTR) {
 219           adns__tcp_broken(ads,"connect/read",strerror(errno));
 220         }
 221       }
 222     }
 223     break;
 224   case server_ok:
 225     count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
 226             callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
 227       (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
 228     if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
 229       skip= 0;
 230       for (;;) {
 231         if (ads->tcprecv.used<skip+2) {
 232           want= 2;
 233         } else {
 234           dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
 235           if (ads->tcprecv.used<skip+2+dgramlen) {
 236             want= 2+dgramlen;
 237           } else {
 238             adns__procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver,now);
 239             skip+= 2+dgramlen; continue;
 240           }
 241         }
 242         ads->tcprecv.used -= skip;
 243         memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
 244         adns__vbuf_ensure(&ads->tcprecv,want);
 245         if (ads->tcprecv.used >= ads->tcprecv.avail) break;
 246         r= read(ads->tcpsocket,
 247                 ads->tcprecv.buf+ads->tcprecv.used,
 248                 ads->tcprecv.avail-ads->tcprecv.used);
 249         if (r>0) {
 250           ads->tcprecv.used+= r;
 251         } else {
 252           if (r<0) {
 253             if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
 254             if (errno==EINTR) continue;
 255           }
 256           adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
 257           break;
 258         }
 259       }
 260     } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
 261       adns__tcp_broken(ads,"select","exceptional condition detected");
 262     } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
 263       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
 264       if (r<0) {
 265         if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
 266           adns__tcp_broken(ads,"write",strerror(errno));
 267         }
 268       } else if (r>0) {
 269         ads->tcpsend.used -= r;
 270         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 271       }
 272     }
 273   default:
 274     abort();
 275   }
 276
 277   if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
 278     count++;
 279     for (;;) {
 280       udpaddrlen= sizeof(udpaddr);
 281       r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
 282       if (r<0) {
 283         if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
 284               errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
 285           adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
 286         break;
 287       }
 288       if (udpaddrlen != sizeof(udpaddr)) {
 289         adns__diag(ads,-1,0,"datagram received with wrong address length %d"
 290                    " (expected %d)", udpaddrlen,sizeof(udpaddr));
 291         continue;
 292       }
 293       if (udpaddr.sin_family != AF_INET) {
 294         adns__diag(ads,-1,0,"datagram received with wrong protocol family"
 295                    " %u (expected %u)",udpaddr.sin_family,AF_INET);
 296         continue;
 297       }
 298       if (ntohs(udpaddr.sin_port) != DNS_PORT) {
 299         adns__diag(ads,-1,0,"datagram received from wrong port %u (expected %u)",
 300                    ntohs(udpaddr.sin_port),DNS_PORT);
 301         continue;
 302       }
 303       for (serv= 0;
 304            serv < ads->nservers &&
 305              ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
 306            serv++);
 307       if (serv >= ads->nservers) {
 308         adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
 309                    inet_ntoa(udpaddr.sin_addr));
 310         continue;
 311       }
 312       adns__procdgram(ads,udpbuf,r,serv,now);
 313     }
 314   }
 315   return count;
 316 }
 317
 318 int adns_callback(adns_state ads, int maxfd,
 319                   const fd_set *readfds, const fd_set *writefds,
 320                   const fd_set *exceptfds) {
 321   struct timeval now;
 322   int r;
 323
 324   r= gettimeofday(&now,0); if (r) return -1;
 325   checktimeouts(ads,now,0,0);
 326   return internal_callback(ads,maxfd,readfds,writefds,exceptfds,now);
 327 }
 328
 329 /* User-visible functions and their implementation. */
 330
 331 void adns__autosys(adns_state ads, struct timeval now) {
 332   if (ads->iflags & adns_if_noautosys) return;
 333   adns_callback(ads,-1,0,0,0);
 334 }
 335
 336 static int internal_check(adns_state ads,
 337                           adns_query *query_io,
 338                           adns_answer **answer,
 339                           void **context_r) {
 340   adns_query qu;
 341
 342   qu= *query_io;
 343   if (!qu) {
 344     if (!ads->output.head) return EWOULDBLOCK;
 345     qu= ads->output.head;
 346   } else {
 347     if (qu->id>=0) return EWOULDBLOCK;
 348   }
 349   LIST_UNLINK(ads->output,qu);
 350   *answer= qu->answer;
 351   if (context_r) *context_r= qu->context.ext;
 352   free(qu);
 353   return 0;
 354 }
 355
 356 int adns_wait(adns_state ads,
 357               adns_query *query_io,
 358               adns_answer **answer_r,
 359               void **context_r) {
 360   int r, maxfd, rsel, rcb;
 361   fd_set readfds, writefds, exceptfds;
 362   struct timeval tvbuf, *tvp;
 363
 364   for (;;) {
 365     r= internal_check(ads,query_io,answer_r,context_r);
 366     if (r != EWOULDBLOCK) return r;
 367     maxfd= 0; tvp= 0;
 368     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 369     adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
 370     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 371     if (rsel==-1) return r;
 372     rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
 373     assert(rcb==rsel);
 374   }
 375 }
 376
 377 int adns_check(adns_state ads,
 378                adns_query *query_io,
 379                adns_answer **answer_r,
 380                void **context_r) {
 381   struct timeval now;
 382   int r;
 383
 384   r= gettimeofday(&now,0); if (r) return errno;
 385   adns__autosys(ads,now);
 386   return internal_check(ads,query_io,answer_r,context_r);
 387 }