event.c

adns for unix/linux, adns-1.3.tar.gz

      ads->tcprecv_skip= 0;
      if (!adns__vbuf_ensure(&ads->tcprecv,want)) { r= ENOMEM; goto xit; }
      assert(ads->tcprecv.used <= ads->tcprecv.avail);
      if (ads->tcprecv.used == ads->tcprecv.avail) continue;
      r= read(ads->tcpsocket,
	      ads->tcprecv.buf+ads->tcprecv.used,
	      ads->tcprecv.avail-ads->tcprecv.used);
      if (r>0) {
	ads->tcprecv.used+= r;
      } else {
	if (r) {
	  if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
	  if (errno==EINTR) continue;
	  if (errno_resources(errno)) { r= errno; goto xit; }
	}
	adns__tcp_broken(ads,"read",r?strerror(errno):"closed");
      }
    } while (ads->tcpstate == server_ok);
    r= 0; goto xit;
  default:
    abort();
  }
  if (fd == ads->udpsocket) {
    for (;;) {
      udpaddrlen= sizeof(udpaddr);
      r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,
		  (struct sockaddr*)&udpaddr,&udpaddrlen);
      if (r<0) {
	if (errno == EAGAIN || errno == EWOULDBLOCK) { r= 0; goto xit; }
	if (errno == EINTR) continue;
	if (errno_resources(errno)) { r= errno; goto xit; }
	adns__warn(ads,-1,0,"datagram receive error: %s",strerror(errno));
	r= 0; goto xit;
      }
      if (udpaddrlen != sizeof(udpaddr)) {
	adns__diag(ads,-1,0,"datagram received with wrong address length %d"
		   " (expected %lu)", udpaddrlen,
		   (unsigned long)sizeof(udpaddr));
	continue;
      }
      if (udpaddr.sin_family != AF_INET) {
	adns__diag(ads,-1,0,"datagram received with wrong protocol family"
		   " %u (expected %u)",udpaddr.sin_family,AF_INET);
	continue;
      }
      if (ntohs(udpaddr.sin_port) != DNS_PORT) {
	adns__diag(ads,-1,0,"datagram received from wrong port"
		   " %u (expected %u)", ntohs(udpaddr.sin_port),DNS_PORT);
	continue;
      }
      for (serv= 0;
	   serv < ads->nservers &&
	     ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
	   serv++);
      if (serv >= ads->nservers) {
	adns__warn(ads,-1,0,"datagram received from unknown nameserver %s",
		   inet_ntoa(udpaddr.sin_addr));
	continue;
      }
      adns__procdgram(ads,udpbuf,r,serv,0,*now);
    }
  }
  r= 0;
xit:
  adns__consistency(ads,0,cc_entex);
  return r;
}

int adns_processwriteable(adns_state ads, int fd, const struct timeval *now) {
  int r;
  
  adns__consistency(ads,0,cc_entex);

  switch (ads->tcpstate) {
  case server_disconnected:
  case server_broken:
    break;
  case server_connecting:
    if (fd != ads->tcpsocket) break;
    assert(ads->tcprecv.used==0);
    assert(ads->tcprecv_skip==0);
    for (;;) {
      if (!adns__vbuf_ensure(&ads->tcprecv,1)) { r= ENOMEM; goto xit; }
      r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
      if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
	tcp_connected(ads,*now);
	r= 0; goto xit;
      }
      if (r>0) {
	adns__tcp_broken(ads,"connect/read","sent data before first request");
	r= 0; goto xit;
      }
      if (errno==EINTR) continue;
      if (errno_resources(errno)) { r= errno; goto xit; }
      adns__tcp_broken(ads,"connect/read",strerror(errno));
      r= 0; goto xit;
    } /* not reached */
  case server_ok:
    if (fd != ads->tcpsocket) break;
    while (ads->tcpsend.used) {
      adns__sigpipe_protect(ads);
      r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
      adns__sigpipe_unprotect(ads);
      if (r<0) {
	if (errno==EINTR) continue;
	if (errno==EAGAIN || errno==EWOULDBLOCK) { r= 0; goto xit; }
	if (errno_resources(errno)) { r= errno; goto xit; }
	adns__tcp_broken(ads,"write",strerror(errno));
	r= 0; goto xit;
      } else if (r>0) {
	ads->tcpsend.used -= r;
	memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
      }
    }
    r= 0;
    goto xit;
  default:
    abort();
  }
  r= 0;
xit:
  adns__consistency(ads,0,cc_entex);
  return r;
}
  
int adns_processexceptional(adns_state ads, int fd,
			    const struct timeval *now) {
  adns__consistency(ads,0,cc_entex);
  switch (ads->tcpstate) {
  case server_disconnected:
  case server_broken:
    break;
  case server_connecting:
  case server_ok:
    if (fd != ads->tcpsocket) break;
    adns__tcp_broken(ads,"poll/select","exceptional condition detected");
    break;
  default:
    abort();
  }
  adns__consistency(ads,0,cc_entex);
  return 0;
}

static void fd_event(adns_state ads, int fd,
		     int revent, int pollflag,
		     int maxfd, const fd_set *fds,
		     int (*func)(adns_state, int fd,
				 const struct timeval *now),
		     struct timeval now, int *r_r) {
  int r;
  
  if (!(revent & pollflag)) return;
  if (fds && !(fd<maxfd && FD_ISSET(fd,fds))) return;
  r= func(ads,fd,&now);
  if (r) {
    if (r_r) {
      *r_r= r;
    } else {
      adns__diag(ads,-1,0,"process fd failed after select:"
		 " %s",strerror(errno));
      adns_globalsystemfailure(ads);
    }
  }
}

void adns__fdevents(adns_state ads,
		    const struct pollfd *pollfds, int npollfds,
		    int maxfd, const fd_set *readfds,
		    const fd_set *writefds, const fd_set *exceptfds,
		    struct timeval now, int *r_r) {
  int i, fd, revents;

  for (i=0; i<npollfds; i++) {
    fd= pollfds[i].fd;
    if (fd >= maxfd) maxfd= fd+1;
    revents= pollfds[i].revents;
#define EV(pollfl,fds,how)  \
    fd_event(ads,fd, revents,pollfl, maxfd,fds, adns_process##how,now,r_r)
    EV( POLLIN,  readfds,   readable    );
    EV( POLLOUT, writefds,  writeable   );
    EV( POLLPRI, exceptfds, exceptional );
#undef EV
  }
}

/* Wrappers for select(2). */

void adns_beforeselect(adns_state ads, int *maxfd_io, fd_set *readfds_io,
		       fd_set *writefds_io, fd_set *exceptfds_io,
		       struct timeval **tv_mod, struct timeval *tv_tobuf,
		       const struct timeval *now) {
  struct timeval tv_nowbuf;
  struct pollfd pollfds[MAX_POLLFDS];
  int i, fd, maxfd, npollfds;
  
  adns__consistency(ads,0,cc_entex);

  if (tv_mod && (!*tv_mod || (*tv_mod)->tv_sec || (*tv_mod)->tv_usec)) {
    /* The caller is planning to sleep. */
    adns__must_gettimeofday(ads,&now,&tv_nowbuf);
    if (!now) { inter_immed(tv_mod,tv_tobuf); goto xit; }
    adns__timeouts(ads, 0, tv_mod,tv_tobuf, *now);
  }

  npollfds= adns__pollfds(ads,pollfds);
  maxfd= *maxfd_io;
  for (i=0; i<npollfds; i++) {
    fd= pollfds[i].fd;
    if (fd >= maxfd) maxfd= fd+1;
    if (pollfds[i].events & POLLIN) FD_SET(fd,readfds_io);
    if (pollfds[i].events & POLLOUT) FD_SET(fd,writefds_io);
    if (pollfds[i].events & POLLPRI) FD_SET(fd,exceptfds_io);
  }
  *maxfd_io= maxfd;

xit:
  adns__consistency(ads,0,cc_entex);
}

void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
		      const fd_set *writefds, const fd_set *exceptfds,
		      const struct timeval *now) {
  struct timeval tv_buf;
  struct pollfd pollfds[MAX_POLLFDS];
  int npollfds, i;

  adns__consistency(ads,0,cc_entex);
  adns__must_gettimeofday(ads,&now,&tv_buf);
  if (!now) goto xit;
  adns_processtimeouts(ads,now);

  npollfds= adns__pollfds(ads,pollfds);
  for (i=0; i<npollfds; i++) pollfds[i].revents= POLLIN|POLLOUT|POLLPRI;
  adns__fdevents(ads,
		 pollfds,npollfds,
		 maxfd,readfds,writefds,exceptfds,
		 *now, 0);
xit:
  adns__consistency(ads,0,cc_entex);
}

/* General helpful functions. */

void adns_globalsystemfailure(adns_state ads) {
  adns__consistency(ads,0,cc_entex);

  while (ads->udpw.head) adns__query_fail(ads->udpw.head, adns_s_systemfail);
  while (ads->tcpw.head) adns__query_fail(ads->tcpw.head, adns_s_systemfail);
  
  switch (ads->tcpstate) {
  case server_connecting:
  case server_ok:
    adns__tcp_broken(ads,0,0);
    break;
  case server_disconnected:
  case server_broken:
    break;
  default:
    abort();
  }
  adns__consistency(ads,0,cc_entex);
}

int adns_processany(adns_state ads) {
  int r, i;
  struct timeval now;
  struct pollfd pollfds[MAX_POLLFDS];
  int npollfds;

  adns__consistency(ads,0,cc_entex);

  r= gettimeofday(&now,0);
  if (!r) adns_processtimeouts(ads,&now);

  /* We just use adns__fdevents to loop over the fd's trying them.
   * This seems more sensible than calling select, since we're most
   * likely just to want to do a read on one or two fds anyway.
   */
  npollfds= adns__pollfds(ads,pollfds);
  for (i=0; i<npollfds; i++) pollfds[i].revents= pollfds[i].events & ~POLLPRI;
  adns__fdevents(ads,
		 pollfds,npollfds,
		 0,0,0,0,
		 now,&r);

  adns__consistency(ads,0,cc_entex);
  return 0;
}

void adns__autosys(adns_state ads, struct timeval now) {
  if (ads->iflags & adns_if_noautosys) return;
  adns_processany(ads);
}

int adns__internal_check(adns_state ads,
			 adns_query *query_io,
			 adns_answer **answer,
			 void **context_r) {
  adns_query qu;

  qu= *query_io;
  if (!qu) {
    if (ads->output.head) {
      qu= ads->output.head;
    } else if (ads->udpw.head || ads->tcpw.head) {
      return EAGAIN;
    } else {
      return ESRCH;
    }
  } else {
    if (qu->id>=0) return EAGAIN;
  }
  LIST_UNLINK(ads->output,qu);
  *answer= qu->answer;
  if (context_r) *context_r= qu->ctx.ext;
  *query_io= qu;
  free(qu);
  return 0;
}

int adns_wait(adns_state ads,
	      adns_query *query_io,
	      adns_answer **answer_r,
	      void **context_r) {
  int r, maxfd, rsel;
  fd_set readfds, writefds, exceptfds;
  struct timeval tvbuf, *tvp;
  
  adns__consistency(ads,*query_io,cc_entex);
  for (;;) {
    r= adns__internal_check(ads,query_io,answer_r,context_r);
    if (r != EAGAIN) break;
    maxfd= 0; tvp= 0;
    FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
    adns_beforeselect(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf,0);
    assert(tvp);
    rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
    if (rsel==-1) {
      if (errno == EINTR) {
	if (ads->iflags & adns_if_eintr) { r= EINTR; break; }
      } else {
	adns__diag(ads,-1,0,"select failed in wait: %s",strerror(errno));
	adns_globalsystemfailure(ads);
      }
    } else {
      assert(rsel >= 0);
      adns_afterselect(ads,maxfd,&readfds,&writefds,&exceptfds,0);
    }
  }
  adns__consistency(ads,0,cc_entex);
  return r;
}

int adns_check(adns_state ads,
	       adns_query *query_io,
	       adns_answer **answer_r,
	       void **context_r) {
  struct timeval now;
  int r;
  
  adns__consistency(ads,*query_io,cc_entex);
  r= gettimeofday(&now,0);
  if (!r) adns__autosys(ads,now);

  r= adns__internal_check(ads,query_io,answer_r,context_r);
  adns__consistency(ads,0,cc_entex);
  return r;
}