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

   1 /**/
   2
   3 #include "adns-internal.h"
   4
   5 static void autosys(adns_state ads, struct timeval now) {
   6   if (ads->iflags & adns_if_noautosys) return;
   7   adns_callback(ads,-1,0,0,0);
   8 }
   9
  10 static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
  11   return maxfd<0 || !fds ? 1 :
  12          fd<maxfd && FD_ISSET(fd,fds);
  13 }
  14
  15 static void tcpserver_broken(adns_state ads, const char *what, const char *why) {
  16   assert(ads->tcpstate == server_connecting || ads->tcpstate == server_connected);
  17   warn("nameserver %s TCP connection lost: %s: %s",
  18        inet_ntoa(ads->servers[tcpserver].addr,what,why));
  19   close(ads->tcpsocket);
  20   ads->tcpstate= server_disconnected;
  21
  22
  23 int adns_callback(adns_state ads, int maxfd,
  24                   const fd_set *readfds, const fd_set *writefds,
  25                   const fd_set *exceptfds) {
  26   int skip, dgramlen, count, udpaddrlen;
  27   enum adns__tcpstate oldtcpstate;
  28   unsigned char udpbuf[UDPMAXDGRAM];
  29   struct sockaddr_in udpaddr;
  30
  31   count= 0;
  32   oldtcpstate= ads->tcpstate;
  33
  34   if (ads->tcpstate == server_connecting) {
  35     if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
  36       count++;
  37       assert(ads->tcprecv.used==0);
  38       vbuf_ensure(&ads->tcprecv,1);
  39       if (ads->tcprecv.buf) {
  40         r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
  41         if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
  42           debug("nameserver %s TCP connected",
  43                 inet_ntoa(ads->servers[ads->tcpserver].addr));
  44           ads->tcpstate= server_connected;
  45         } else if (r>0) {
  46           tcpserver_broken(ads,"connect/read","sent data before first request");
  47         } else if (errno!=EINTR) {
  48           tcpserver_broken(ads,"connect",strerror(errno));
  49         }
  50       }
  51     }
  52   }
  53   if (ads->tcpstate == server_connected) {
  54     if (oldtcpstate == server_connected)
  55       count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
  56               callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
  57         (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
  58     if (oldtcpstate != server_connected || callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
  59       skip= 0;
  60       for (;;) {
  61         if (ads->tcprecv.used<skip+2) {
  62           want= 2;
  63         } else {
  64           dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
  65           if (ads->tcprecv.used<skip+2+dgramlen) {
  66             want= 2+dgramlen;
  67           } else {
  68             procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver);
  69             skip+= 2+dgramlen; continue;
  70           }
  71         }
  72         ads->tcprecv.used -= skip;
  73         memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
  74         vbuf_ensure(&ads->tcprecv,want);
  75         if (ads->tcprecv.used >= ads->tcprecv.avail) break;
  76         r= read(ads->tcpsocket,
  77                 ads->tcprecv.buf+ads->tcprecv.used,
  78                 ads->tcprecv.avail-ads->tcprecv.used);
  79         if (r>0) {
  80           ads->tcprecv.used+= r;
  81         } else {
  82           if (r<0) {
  83             if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
  84             if (errno==EINTR) continue;
  85           }
  86           tcpserver_broken(ads->tcpserver,"read",r?strerror(errno):"closed");
  87           break;
  88         }
  89       }
  90     } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
  91       tcpserver_broken(ads->tcpserver,"select","exceptional condition detected");
  92     } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
  93       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
  94       if (r<0) {
  95         if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
  96           tcpserver_broken(ads->tcpserver,"write",strerror(errno));
  97         }
  98       } else if (r>0) {
  99         ads->tcpsend.used -= r;
 100         memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
 101       }
 102     }
 103   }
 104
 105   if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
 106     count++;
 107     for (;;) {
 108       udpaddrlen= sizeof(udpaddr);
 109       r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
 110       if (r<0) {
 111         if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
 112               errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
 113           warn("datagram receive error: %s",strerror(errno));
 114         break;
 115       }
 116       if (udpaddrlen != sizeof(udpaddr)) {
 117         diag("datagram received with wrong address length %d (expected %d)",
 118              udpaddrlen,sizeof(udpaddr));
 119         continue;
 120       }
 121       if (udpaddr.sin_family != AF_INET) {
 122         diag("datagram received with wrong protocol family %u (expected %u)",
 123              udpaddr.sin_family,AF_INET);
 124         continue;
 125       }
 126       if (ntohs(udpaddr.sin_port) != NSPORT) {
 127         diag("datagram received from wrong port %u (expected %u)",
 128              ntohs(udpaddr.sin_port),NSPORT);
 129         continue;
 130       }
 131       for (serv= 0;
 132            serv < ads->nservers &&
 133              ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
 134            serv++);
 135       if (serv >= ads->nservers) {
 136         warn("datagram received from unknown nameserver %s",inet_ntoa(udpaddr.sin_addr));
 137         continue;
 138       }
 139       procdgram(ads,udpbuf,r,serv);
 140     }
 141   }
 142 }
 143
 144 static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
 145                         struct timeval maxto) {
 146   struct timeval rbuf;
 147
 148   rbuf= *tv_io;
 149   if (!rbuf) { *tvbuf= maxto; *tv_io= tvbuf; return; }
 150   if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
 151 }
 152
 153 static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
 154                            struct timeval now, struct timeval maxtime) {
 155   ldiv_t dr;
 156
 157   maxtime.tv_sec -= (now.tv_sec-1);
 158   maxtime.tv_usec += (1000-now.tv_usec);
 159   dr= ldiv(maxtime.tv_usec,1000);
 160   maxtime.tv_sec += dr.quot;
 161   maxtime.tv_usec -= dr.rem;
 162   inter_maxto(tv_io,tvbuf,maxtime);
 163 }
 164
 165 static void localresourcerr(struct timeval **tv_io, struct timeval *tvbuf,
 166                             const char *syscall) {
 167   struct timeval tvto_lr;
 168
 169   warn(ads,"local system resources scarce (during %s): %s",syscall,strerror(errno));
 170   timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
 171   inter_maxto(tv_io, tvbuf, tvto_lr);
 172   return;
 173 }
 174
 175 static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
 176   if (fd>=*maxfd) *maxfd= fd+1;
 177   FD_SET(fd,fds);
 178 }
 179
 180 void adns_interest(adns_state ads, int *maxfd,
 181                    fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 182                    struct timeval **tv_io, struct timeval *tvbuf) {
 183   struct timeval now;
 184   adns_query qu;
 185   int r;
 186
 187   r= gettimeofday(&now,0);
 188   if (r) { localresourcerr(tv_io,tvbuf,"gettimeofday"); return; }
 189
 190   for (qu= ads->timew; qu; qu= nqu) {
 191     nqu= qu->next;
 192     if (timercmp(&now,qu->timeout,>)) {
 193       DLIST_UNLINK(ads->timew,qu);
 194       if (qu->nextudpserver == -1) {
 195         query_fail(ads,qu,adns_s_notresponding);
 196       } else {
 197         DLIST_LINKTAIL(ads->tosend,qu);
 198       }
 199     } else {
 200       inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
 201     }
 202   }
 203
 204   for (qu= ads->tosend; qu; qu= nqu) {
 205     nqu= qu->next;
 206     quproc_tosend(ads,qu,now);
 207   }
 208
 209   inter_addfd(maxfd,readfds,ads->udpsocket);
 210
 211   switch (ads->tcpstate) {
 212   case server_disc:
 213     break;
 214   case server_connecting:
 215     inter_addfd(maxfd,writefds,ads->tcpsocket);
 216     break;
 217   case server_connected:
 218     inter_addfd(maxfd,readfds,ads->tcpsocket);
 219     inter_addfd(maxfd,exceptfds,ads->tcpsocket);
 220     if (ads->opbufused) inter_addfd(maxfd,writefds,ads->tcpsocket);
 221   default:
 222     abort();
 223   }
 224 }
 225
 226 static int internal_check(adns_state ads,
 227                           adns_query *query_io,
 228                           adns_answer **answer,
 229                           void **context_r) {
 230   adns_query qu;
 231
 232   qu= *query_io;
 233   if (!qu) {
 234     if (!ads->output.head) return EWOULDBLOCK;
 235     qu= ads->output.head;
 236   } else {
 237     if (qu->id>=0) return EWOULDBLOCK;
 238   }
 239   LIST_UNLINK(ads->output,qu);
 240   *answer= qu->answer;
 241   if (context_r) *context_r= qu->context;
 242   free(qu);
 243   return 0;
 244 }
 245
 246 int adns_wait(adns_state ads,
 247               adns_query *query_io,
 248               adns_answer **answer_r,
 249               void **context_r) {
 250   int r, maxfd, rsel, rcb;
 251   fd_set readfds, writefds, exceptfds;
 252   struct timeval tvbuf, *tvp;
 253
 254   for (;;) {
 255     r= internal_check(ads,query_io,answer_r,context_r);
 256     if (r && r != EWOULDBLOCK) return r;
 257     maxfd= 0; tvp= 0;
 258     FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
 259     adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
 260     rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
 261     if (rsel==-1) return r;
 262     rcb= adns_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
 263     assert(rcb==rsel);
 264   }
 265 }
 266
 267 int adns_check(adns_state ads,
 268                adns_query *query_io,
 269                adns_answer **answer_r,
 270                void **context_r) {
 271   autosys(ads);
 272   return internal_check(ads,query_io,answer_r,context_r);
 273 }