[adns] / src / event.c

/**/

#include "adns-internal.h"

/* TCP connection management */

void adns__tcp_broken(adns_state ads, const char *what, const char *why) {
  int serv;
  
  assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
  serv= ads->tcpserver;
  warn("TCP connection lost: %s: %s",serv,why);
  close(ads->tcpsocket);
  ads->tcpstate= server_disconnected;
  
  for (qu= ads->timew; qu; qu= nqu) {
    nqu= qu->next;
    if (qu->state == query_udp) continue;
    assert(qu->state == query_tcpwait || qu->state == query_tcpsent);
    qu->state= query_tcpwait;
    qu->tcpfailed |= (1<<serv);
    if (qu->tcpfailed == (1<<ads->nservers)-1) {
      DLIST_UNLINK(ads->timew,qu);
      adns__query_fail(ads,qu,adns_s_allservfail);
    }
  }

  ads->tcpbuf.used= 0;
  ads->tcpserver= (serv+1)%ads->nservers;
}

static void tcp_connected(adns_state ads, struct timeval now) {
  debug("TCP connected",ads->tcpserver);
  ads->tcpstate= server_connected;
  for (qu= ads->timew.head; qu; qu= nqu) {
    nqu= qu->next;
    if (qu->state == query_udp) continue;
    assert (qu->state == query_tcpwait);
    adns__query_tcp(ads,qu,now);
  }
}

void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
  int r, fd, tries;
  sockaddr_in addr;
  /* fixme: single TCP timeout, not once per server */

  for (tries=0; tries<ads->nservers; tries++) {
    if (ads->tcpstate == server_connecting || ads->tcpstate == server_ok) return;
    assert(ads->tcpstate == server_disconnected);
    assert(!ads->tcpbuf.used);

    proto= getprotobyname("tcp");
    if (!proto) { diag(ads,"unable to find protocol number for TCP !",-1); return; }
    fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
    if (fd<0) { diag(ads,"cannot create TCP socket: %s",-1,strerror(errno)); return; }
    if (!adns__setnonblock(fd)) return;
    memset(&addr,0,sizeof(addr));
    addr.sin_family= AF_INET;
    addr.sin_port= htons(NSPORT);
    addr.sin_addr= ads->servers[ads->tcpserver].addr;
    r= connect(fd,&addr,sizeof(addr));
    ads->tcpsocket= fd;
    ads->tcpstate= server_connecting;
    if (r==0) { tcp_connected(ads); continue; }
    if (errno == EWOULDBLOCK || errno == EINPROGRESS) return;
    adns__tcp_broken(ads,"connect",strerror(errno));
  }
}

/* Callback procedures - these do the real work of reception and timeout, etc. */

static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
  return maxfd<0 || !fds ? 1 :
         fd<maxfd && FD_ISSET(fd,fds);
}

static int internal_callback(adns_state ads, int maxfd,
			     const fd_set *readfds, const fd_set *writefds,
			     const fd_set *exceptfds) {
  int skip, dgramlen, count, udpaddrlen, oldtcpsocket;
  enum adns__tcpstate oldtcpstate;
  unsigned char udpbuf[UDPMAXDGRAM];
  struct sockaddr_in udpaddr;

  count= 0;

  switch (ads->tcpstate) {
  case server_disconnected:
    break;
  case server_connecting:
    if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
      count++;
      assert(ads->tcprecv.used==0);
      vbuf_ensure(&ads->tcprecv,1);
      if (ads->tcprecv.buf) {
	r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
	if (r==0 || (r<0 && (errno==EAGAIN || errno==EWOULDBLOCK))) {
	  tcpserver_connected(ads);
	} else if (r>0) {
	  tcpserver_broken(ads,"connect/read","sent data before first request");
	} else if (errno!=EINTR) {
	  tcpserver_broken(ads,"connect/read",strerror(errno));
	}
      }
    }
    break;
  case server_ok:
    count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
            callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
      (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
    if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
      skip= 0;
      for (;;) {
	if (ads->tcprecv.used<skip+2) {
	  want= 2;
	} else {
	  dgramlen= (ads->tcprecv.buf[skip]<<8) | ads->tcprecv.buf[skip+1];
	  if (ads->tcprecv.used<skip+2+dgramlen) {
	    want= 2+dgramlen;
	  } else {
	    procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver);
	    skip+= 2+dgramlen; continue;
	  }
	}
	ads->tcprecv.used -= skip;
	memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
	vbuf_ensure(&ads->tcprecv,want);
	if (ads->tcprecv.used >= ads->tcprecv.avail) break;
	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<0) {
	    if (errno==EAGAIN || errno==EWOULDBLOCK || errno==ENOMEM) break;
	    if (errno==EINTR) continue;
	  }
	  tcpserver_broken(ads->tcpserver,"read",r?strerror(errno):"closed");
	  break;
	}
      }
    } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
      tcpserver_broken(ads->tcpserver,"select","exceptional condition detected");
    } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
      r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
      if (r<0) {
	if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
	  tcpserver_broken(ads->tcpserver,"write",strerror(errno));
	}
      } else if (r>0) {
	ads->tcpsend.used -= r;
	memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
      }
    }
  default:
    abort();
  }

  if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
    count++;
    for (;;) {
      udpaddrlen= sizeof(udpaddr);
      r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
      if (r<0) {
	if (!(errno == EAGAIN || errno == EWOULDBLOCK ||
	      errno == EINTR || errno == ENOMEM || errno == ENOBUFS))
	  warn("datagram receive error: %s",strerror(errno));
	break;
      }
      if (udpaddrlen != sizeof(udpaddr)) {
	diag("datagram received with wrong address length %d (expected %d)",
	     udpaddrlen,sizeof(udpaddr));
	continue;
      }
      if (udpaddr.sin_family != AF_INET) {
	diag("datagram received with wrong protocol family %u (expected %u)",
	     udpaddr.sin_family,AF_INET);
	continue;
      }
      if (ntohs(udpaddr.sin_port) != NSPORT) {
	diag("datagram received from wrong port %u (expected %u)",
	     ntohs(udpaddr.sin_port),NSPORT);
	continue;
      }
      for (serv= 0;
	   serv < ads->nservers &&
	     ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
	   serv++);
      if (serv >= ads->nservers) {
	warn("datagram received from unknown nameserver %s",inet_ntoa(udpaddr.sin_addr));
	continue;
      }
      procdgram(ads,udpbuf,r,serv);
    }
  }
}

static void checktimeouts(adns_state ads, struct timeval now,
			  struct timeval **tv_io, struct timeval *tvbuf) {
  for (qu= ads->timew; qu; qu= nqu) {
    nqu= qu->next;
    if (timercmp(&now,qu->timeout,>)) {
      DLIST_UNLINK(ads->timew,qu);
      if (qu->state != state_udp) {
	query_fail(ads,qu,adns_s_notresponding);
      } else {
	adns__query_udp(ads,qu,now);
      }
    } else {
      inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
    }
  }
}  
 
int adns_callback(adns_state ads, int maxfd,
		  const fd_set *readfds, const fd_set *writefds,
		  const fd_set *exceptfds) {
  struct timeval now;

  r= gettimeofday(&now,0);
  if (!r) checktimeouts(ads,now,0,0);
  return internal_callback(ads,maxfd,readfds,writefds,exceptfds);
}

/* `Interest' functions - find out which fd's we might be interested in,
 * and when we want to be called back for a timeout.
 */

static void inter_maxto(struct timeval **tv_io, struct timeval *tvbuf,
			struct timeval maxto) {
  struct timeval rbuf;

  if (!tv_io) return;
  rbuf= *tv_io;
  if (!rbuf) { *tvbuf= maxto; *tv_io= tvbuf; return; }
  if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
}

static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
			   struct timeval now, struct timeval maxtime) {
  ldiv_t dr;

  if (!tv_io) return;
  maxtime.tv_sec -= (now.tv_sec-1);
  maxtime.tv_usec += (1000-now.tv_usec);
  dr= ldiv(maxtime.tv_usec,1000);
  maxtime.tv_sec += dr.quot;
  maxtime.tv_usec -= dr.rem;
  inter_maxto(tv_io,tvbuf,maxtime);
}

static void inter_addfd(int *maxfd, fd_set *fds, int fd) {
  if (!maxfd || !fds) return;
  if (fd>=*maxfd) *maxfd= fd+1;
  FD_SET(fd,fds);
}

void adns_interest(adns_state ads, int *maxfd,
		   fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
		   struct timeval **tv_io, struct timeval *tvbuf) {
  struct timeval now;
  struct timeval tvto_lr;
  adns_query qu;
  int r;
  
  r= gettimeofday(&now,0);
  if (r) {
    warn(ads,"gettimeofday failed - will sleep for a bit: %s",-1,strerror(errno));
    timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
    inter_maxto(tv_io, tvbuf, tvto_lr);
  } else {
    checktimeouts(ads,now,tv_io,tvbuf);
  }
  
  inter_addfd(maxfd,readfds,ads->udpsocket);

  switch (ads->tcpstate) {
  case server_disc:
    break;
  case server_connecting:
    inter_addfd(maxfd,writefds,ads->tcpsocket);
    break;
  case server_connected:
    inter_addfd(maxfd,readfds,ads->tcpsocket);
    inter_addfd(maxfd,exceptfds,ads->tcpsocket);
    if (ads->opbufused) inter_addfd(maxfd,writefds,ads->tcpsocket);
  default:
    abort();
  }
}

/* User-visible functions and their implementation. */

static void autosys(adns_state ads, struct timeval now) {
  if (ads->iflags & adns_if_noautosys) return;
  adns_callback(ads,-1,0,0,0);
}

static int 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) return EWOULDBLOCK;
    qu= ads->output.head;
  } else {
    if (qu->id>=0) return EWOULDBLOCK;
  }
  LIST_UNLINK(ads->output,qu);
  *answer= qu->answer;
  if (context_r) *context_r= qu->context;
  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, rcb;
  fd_set readfds, writefds, exceptfds;
  struct timeval tvbuf, *tvp;
  
  for (;;) {
    r= internal_check(ads,query_io,answer_r,context_r);
    if (r && r != EWOULDBLOCK) return r;
    maxfd= 0; tvp= 0;
    FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
    adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
    rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
    if (rsel==-1) return r;
    rcb= internal_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
    assert(rcb==rsel);
  }
}

int adns_check(adns_state ads,
	       adns_query *query_io,
	       adns_answer **answer_r,
	       void **context_r) {
  autosys(ads);
  return internal_check(ads,query_io,answer_r,context_r);
}
Commit	Line	Data
656b2da9	1	/**/
656b2da9	2
37e28fde	3	#include "adns-internal.h"
37e28fde	4
ddfda861	5	/* TCP connection management */
656b2da9	6
8402e34c	7	void adns__tcp_broken(adns_state ads, const char what, const char why) {
	8	int serv;
	9
	10	assert(ads->tcpstate == server_connecting \|\| ads->tcpstate == server_ok);
ddfda861	11	serv= ads->tcpserver;
ddfda861	12	warn("TCP connection lost: %s: %s",serv,why);
37e28fde	13	close(ads->tcpsocket);
	14	ads->tcpstate= server_disconnected;
	15
8402e34c	16	for (qu= ads->timew; qu; qu= nqu) {
8402e34c	17	nqu= qu->next;
ddfda861	18	if (qu->state == query_udp) continue;
	19	assert(qu->state == query_tcpwait \|\| qu->state == query_tcpsent);
	20	qu->state= query_tcpwait;
	21	qu->tcpfailed \|= (1<<serv);
	22	if (qu->tcpfailed == (1<<ads->nservers)-1) {
	23	DLIST_UNLINK(ads->timew,qu);
	24	adns__query_fail(ads,qu,adns_s_allservfail);
	25	}
8402e34c	26	}
	27
	28	ads->tcpbuf.used= 0;
	29	ads->tcpserver= (serv+1)%ads->nservers;
	30	}
	31
ddfda861	32	static void tcp_connected(adns_state ads, struct timeval now) {
	33	debug("TCP connected",ads->tcpserver);
	34	ads->tcpstate= server_connected;
	35	for (qu= ads->timew.head; qu; qu= nqu) {
	36	nqu= qu->next;
	37	if (qu->state == query_udp) continue;
	38	assert (qu->state == query_tcpwait);
	39	adns__query_tcp(ads,qu,now);
	40	}
	41	}
	42
	43	void adns__tcp_tryconnect(adns_state ads, struct timeval now) {
8402e34c	44	int r, fd, tries;
8402e34c	45	sockaddr_in addr;
ddfda861	46	/* fixme: single TCP timeout, not once per server */
8402e34c	47
	48	for (tries=0; tries<ads->nservers; tries++) {
	49	if (ads->tcpstate == server_connecting \|\| ads->tcpstate == server_ok) return;
	50	assert(ads->tcpstate == server_disconnected);
	51	assert(!ads->tcpbuf.used);
	52
	53	proto= getprotobyname("tcp");
	54	if (!proto) { diag(ads,"unable to find protocol number for TCP !",-1); return; }
	55	fd= socket(AF_INET,SOCK_STREAM,proto->p_proto);
	56	if (fd<0) { diag(ads,"cannot create TCP socket: %s",-1,strerror(errno)); return; }
	57	if (!adns__setnonblock(fd)) return;
	58	memset(&addr,0,sizeof(addr));
	59	addr.sin_family= AF_INET;
	60	addr.sin_port= htons(NSPORT);
	61	addr.sin_addr= ads->servers[ads->tcpserver].addr;
	62	r= connect(fd,&addr,sizeof(addr));
	63	ads->tcpsocket= fd;
	64	ads->tcpstate= server_connecting;
ddfda861	65	if (r==0) { tcp_connected(ads); continue; }
8402e34c	66	if (errno == EWOULDBLOCK \|\| errno == EINPROGRESS) return;
ddfda861	67	adns__tcp_broken(ads,"connect",strerror(errno));
8402e34c	68	}
	69	}
	70
ddfda861	71	/* Callback procedures - these do the real work of reception and timeout, etc. */
	72
	73	static int callb_checkfd(int maxfd, const fd_set *fds, int fd) {
	74	return maxfd<0 \|\| !fds ? 1 :
	75	fd<maxfd && FD_ISSET(fd,fds);
	76	}
	77
	78	static int internal_callback(adns_state ads, int maxfd,
	79	const fd_set readfds, const fd_set writefds,
	80	const fd_set *exceptfds) {
	81	int skip, dgramlen, count, udpaddrlen, oldtcpsocket;
656b2da9	82	enum adns__tcpstate oldtcpstate;
37e28fde	83	unsigned char udpbuf[UDPMAXDGRAM];
37e28fde	84	struct sockaddr_in udpaddr;
656b2da9	85
656b2da9	86	count= 0;
ddfda861	87
	88	switch (ads->tcpstate) {
	89	case server_disconnected:
	90	break;
	91	case server_connecting:
656b2da9	92	if (callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
	93	count++;
	94	assert(ads->tcprecv.used==0);
	95	vbuf_ensure(&ads->tcprecv,1);
	96	if (ads->tcprecv.buf) {
	97	r= read(ads->tcpsocket,&ads->tcprecv.buf,1);
	98	if (r==0 \|\| (r<0 && (errno==EAGAIN \|\| errno==EWOULDBLOCK))) {
ddfda861	99	tcpserver_connected(ads);
656b2da9	100	} else if (r>0) {
	101	tcpserver_broken(ads,"connect/read","sent data before first request");
	102	} else if (errno!=EINTR) {
8402e34c	103	tcpserver_broken(ads,"connect/read",strerror(errno));
656b2da9	104	}
	105	}
	106	}
ddfda861	107	break;
	108	case server_ok:
	109	count+= callb_checkfd(maxfd,readfds,ads->tcpsocket) +
	110	callb_checkfd(maxfd,exceptfds,ads->tcpsocket) +
	111	(ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket));
	112	if (callb_checkfd(maxfd,readfds,ads->tcpsocket)) {
656b2da9	113	skip= 0;
	114	for (;;) {
	115	if (ads->tcprecv.used<skip+2) {
	116	want= 2;
	117	} else {
	118	dgramlen= (ads->tcprecv.buf[skip]<<8) \| ads->tcprecv.buf[skip+1];
	119	if (ads->tcprecv.used<skip+2+dgramlen) {
	120	want= 2+dgramlen;
	121	} else {
37e28fde	122	procdgram(ads,ads->tcprecv.buf+skip+2,dgramlen,ads->tcpserver);
656b2da9	123	skip+= 2+dgramlen; continue;
	124	}
	125	}
37e28fde	126	ads->tcprecv.used -= skip;
656b2da9	127	memmove(ads->tcprecv.buf,ads->tcprecv.buf+skip,ads->tcprecv.used);
	128	vbuf_ensure(&ads->tcprecv,want);
	129	if (ads->tcprecv.used >= ads->tcprecv.avail) break;
	130	r= read(ads->tcpsocket,
	131	ads->tcprecv.buf+ads->tcprecv.used,
	132	ads->tcprecv.avail-ads->tcprecv.used);
	133	if (r>0) {
	134	ads->tcprecv.used+= r;
	135	} else {
	136	if (r<0) {
	137	if (errno==EAGAIN \|\| errno==EWOULDBLOCK \|\| errno==ENOMEM) break;
	138	if (errno==EINTR) continue;
	139	}
	140	tcpserver_broken(ads->tcpserver,"read",r?strerror(errno):"closed");
	141	break;
	142	}
	143	}
	144	} else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
	145	tcpserver_broken(ads->tcpserver,"select","exceptional condition detected");
	146	} else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
	147	r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
	148	if (r<0) {
	149	if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
	150	tcpserver_broken(ads->tcpserver,"write",strerror(errno));
	151	}
	152	} else if (r>0) {
	153	ads->tcpsend.used -= r;
	154	memmove(ads->tcpsend.buf,ads->tcpsend.buf+r,ads->tcpsend.used);
	155	}
	156	}
ddfda861	157	default:
ddfda861	158	abort();
656b2da9	159	}
656b2da9	160
37e28fde	161	if (callb_checkfd(maxfd,readfds,ads->udpsocket)) {
	162	count++;
	163	for (;;) {
	164	udpaddrlen= sizeof(udpaddr);
	165	r= recvfrom(ads->udpsocket,udpbuf,sizeof(udpbuf),0,&udpaddr,&udpaddrlen);
	166	if (r<0) {
	167	if (!(errno == EAGAIN \|\| errno == EWOULDBLOCK \|\|
	168	errno == EINTR \|\| errno == ENOMEM \|\| errno == ENOBUFS))
	169	warn("datagram receive error: %s",strerror(errno));
	170	break;
	171	}
	172	if (udpaddrlen != sizeof(udpaddr)) {
	173	diag("datagram received with wrong address length %d (expected %d)",
	174	udpaddrlen,sizeof(udpaddr));
	175	continue;
	176	}
	177	if (udpaddr.sin_family != AF_INET) {
	178	diag("datagram received with wrong protocol family %u (expected %u)",
	179	udpaddr.sin_family,AF_INET);
	180	continue;
	181	}
	182	if (ntohs(udpaddr.sin_port) != NSPORT) {
	183	diag("datagram received from wrong port %u (expected %u)",
	184	ntohs(udpaddr.sin_port),NSPORT);
	185	continue;
	186	}
	187	for (serv= 0;
	188	serv < ads->nservers &&
	189	ads->servers[serv].addr.s_addr != udpaddr.sin_addr.s_addr;
	190	serv++);
	191	if (serv >= ads->nservers) {
	192	warn("datagram received from unknown nameserver %s",inet_ntoa(udpaddr.sin_addr));
	193	continue;
	194	}
	195	procdgram(ads,udpbuf,r,serv);
656b2da9	196	}
37e28fde	197	}
656b2da9	198	}
656b2da9	199
ddfda861	200	static void checktimeouts(adns_state ads, struct timeval now,
	201	struct timeval *tv_io, struct timeval tvbuf) {
	202	for (qu= ads->timew; qu; qu= nqu) {
	203	nqu= qu->next;
	204	if (timercmp(&now,qu->timeout,>)) {
	205	DLIST_UNLINK(ads->timew,qu);
	206	if (qu->state != state_udp) {
	207	query_fail(ads,qu,adns_s_notresponding);
	208	} else {
	209	adns__query_udp(ads,qu,now);
	210	}
	211	} else {
	212	inter_maxtoabs(tv_io,tvbuf,now,qu->timeout);
	213	}
	214	}
	215	}
	216
	217	int adns_callback(adns_state ads, int maxfd,
	218	const fd_set readfds, const fd_set writefds,
	219	const fd_set *exceptfds) {
	220	struct timeval now;
	221
	222	r= gettimeofday(&now,0);
	223	if (!r) checktimeouts(ads,now,0,0);
	224	return internal_callback(ads,maxfd,readfds,writefds,exceptfds);
	225	}
	226
	227	/* `Interest' functions - find out which fd's we might be interested in,
	228	* and when we want to be called back for a timeout.
	229	*/
	230
656b2da9	231	static void inter_maxto(struct timeval *tv_io, struct timeval tvbuf,
	232	struct timeval maxto) {
	233	struct timeval rbuf;
	234
ddfda861	235	if (!tv_io) return;
656b2da9	236	rbuf= *tv_io;
	237	if (!rbuf) { tvbuf= maxto; tv_io= tvbuf; return; }
	238	if (timercmp(rbuf,&maxto,>)) *rbuf= maxto;
	239	}
	240
	241	static void inter_maxtoabs(struct timeval *tv_io, struct timeval tvbuf,
	242	struct timeval now, struct timeval maxtime) {
	243	ldiv_t dr;
ddfda861	244
ddfda861	245	if (!tv_io) return;
656b2da9	246	maxtime.tv_sec -= (now.tv_sec-1);
	247	maxtime.tv_usec += (1000-now.tv_usec);
	248	dr= ldiv(maxtime.tv_usec,1000);
	249	maxtime.tv_sec += dr.quot;
	250	maxtime.tv_usec -= dr.rem;
	251	inter_maxto(tv_io,tvbuf,maxtime);
	252	}
	253
656b2da9	254	static void inter_addfd(int maxfd, fd_set fds, int fd) {
ddfda861	255	if (!maxfd \|\| !fds) return;
656b2da9	256	if (fd>=maxfd) maxfd= fd+1;
	257	FD_SET(fd,fds);
	258	}
	259
	260	void adns_interest(adns_state ads, int *maxfd,
	261	fd_set readfds, fd_set writefds, fd_set *exceptfds,
	262	struct timeval *tv_io, struct timeval tvbuf) {
	263	struct timeval now;
ddfda861	264	struct timeval tvto_lr;
656b2da9	265	adns_query qu;
	266	int r;
	267
	268	r= gettimeofday(&now,0);
ddfda861	269	if (r) {
	270	warn(ads,"gettimeofday failed - will sleep for a bit: %s",-1,strerror(errno));
	271	timerclear(&tvto_lr); timevaladd(&tvto_lr,LOCALRESOURCEMS);
	272	inter_maxto(tv_io, tvbuf, tvto_lr);
	273	} else {
	274	checktimeouts(ads,now,tv_io,tvbuf);
656b2da9	275	}
656b2da9	276
656b2da9	277	inter_addfd(maxfd,readfds,ads->udpsocket);
37e28fde	278
656b2da9	279	switch (ads->tcpstate) {
	280	case server_disc:
	281	break;
	282	case server_connecting:
	283	inter_addfd(maxfd,writefds,ads->tcpsocket);
	284	break;
	285	case server_connected:
	286	inter_addfd(maxfd,readfds,ads->tcpsocket);
	287	inter_addfd(maxfd,exceptfds,ads->tcpsocket);
	288	if (ads->opbufused) inter_addfd(maxfd,writefds,ads->tcpsocket);
	289	default:
	290	abort();
	291	}
656b2da9	292	}
656b2da9	293
ddfda861	294	/* User-visible functions and their implementation. */
	295
	296	static void autosys(adns_state ads, struct timeval now) {
	297	if (ads->iflags & adns_if_noautosys) return;
	298	adns_callback(ads,-1,0,0,0);
	299	}
	300
656b2da9	301	static int internal_check(adns_state ads,
	302	adns_query *query_io,
	303	adns_answer **answer,
	304	void **context_r) {
	305	adns_query qu;
	306
	307	qu= *query_io;
	308	if (!qu) {
	309	if (!ads->output.head) return EWOULDBLOCK;
	310	qu= ads->output.head;
	311	} else {
	312	if (qu->id>=0) return EWOULDBLOCK;
	313	}
	314	LIST_UNLINK(ads->output,qu);
	315	*answer= qu->answer;
	316	if (context_r) *context_r= qu->context;
	317	free(qu);
	318	return 0;
	319	}
	320
	321	int adns_wait(adns_state ads,
	322	adns_query *query_io,
	323	adns_answer **answer_r,
	324	void **context_r) {
	325	int r, maxfd, rsel, rcb;
	326	fd_set readfds, writefds, exceptfds;
	327	struct timeval tvbuf, *tvp;
	328
	329	for (;;) {
	330	r= internal_check(ads,query_io,answer_r,context_r);
	331	if (r && r != EWOULDBLOCK) return r;
656b2da9	332	maxfd= 0; tvp= 0;
37e28fde	333	FD_ZERO(&readfds); FD_ZERO(&writefds); FD_ZERO(&exceptfds);
656b2da9	334	adns_interest(ads,&maxfd,&readfds,&writefds,&exceptfds,&tvp,&tvbuf);
	335	rsel= select(maxfd,&readfds,&writefds,&exceptfds,tvp);
	336	if (rsel==-1) return r;
ddfda861	337	rcb= internal_callback(ads,maxfd,&readfds,&writefds,&exceptfds);
656b2da9	338	assert(rcb==rsel);
	339	}
	340	}
	341
	342	int adns_check(adns_state ads,
	343	adns_query *query_io,
	344	adns_answer **answer_r,
	345	void **context_r) {
	346	autosys(ads);
	347	return internal_check(ads,query_io,answer_r,context_r);
	348	}