/*
 * event.c
 * - event loop core
 * - TCP connection management
 * - user-visible check/wait and event-loop-related functions
 */
/*
 *  This file is
 *    Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
 *
 *  It is part of adns, which is
 *    Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
 *    Copyright (C) 1999-2000 Tony Finch <dot@dotat.at>
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 *
 * $Id: event.c,v 1.2 2003/06/14 13:55:50 tr-ircd Exp $
 */

#include "struct.h"
#include "fileio.h"
#include "internal.h"
#include "fd.h"
#include "h.h"
#include "s_bsd.h"
#include "tvarith.h"

/* TCP connection management. */

static void tcp_close(adns_state ads)
{
int serv;

    serv = ads->tcpserver;
    fd_close(ads->tcpsocket);
    ads->tcpsocket = -1;
    ads->tcprecv.used = ads->tcprecv_skip = ads->tcpsend.used = 0;
}

void adns__tcp_broken(adns_state ads, const char *what, const char *why)
{
    int serv;
    adns_query qu;

    assert(ads->tcpstate == server_connecting || ads->tcpstate == server_ok);
    serv = ads->tcpserver;
    if (what)
	adns__warn(ads, serv, 0, "TCP connection failed: %s: %s", what, why);

    if (ads->tcpstate == server_connecting) {
	/* Counts as a retry for all the queries waiting for TCP. */
	for (qu = ads->tcpw.head; qu; qu = qu->next)
	    qu->retries++;
    }

    tcp_close(ads);
    ads->tcpstate = server_broken;
    ads->tcpserver = (serv + 1) % ads->nservers;
}

static void tcp_connected(adns_state ads, struct timeval now)
{
    adns_query qu, nqu;

    adns__debug(ads, ads->tcpserver, 0, "TCP connected");
    ads->tcpstate = server_ok;
    for (qu = ads->tcpw.head; qu && ads->tcpstate == server_ok; qu = nqu) {
	nqu = qu->next;
	assert(qu->state == query_tcpw);
	adns__querysend_tcp(qu, now);
    }
}

void adns__tcp_tryconnect(adns_state ads, struct timeval now)
{
    int r, fd, tries;
    struct sockaddr_in addr;

    for (tries = 0; tries < ads->nservers; tries++) {
	switch (ads->tcpstate) {
	    case server_connecting:
	    case server_ok:
	    case server_broken:
		return;
	    case server_disconnected:
		break;
	    default:
		abort();
	}

	assert(!ads->tcpsend.used);
	assert(!ads->tcprecv.used);
	assert(!ads->tcprecv_skip);

	fd = comm_open(AF_INET, SOCK_STREAM, 0, "adns TCP socket");
	if (fd < 0) {
	    adns__diag(ads, -1, 0, "cannot create TCP socket: %s", strerror(errno));
	    return;
	}
	r = adns__setnonblock(ads, fd);
	if (r) {
	    adns__diag(ads, -1, 0, "cannot make TCP socket nonblocking: %s", strerror(r));
	    fd_close(fd);
	    return;
	}
	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_port = htons(DNS_PORT);
	addr.sin_addr = ads->servers[ads->tcpserver].addr;
	r = connect(fd, (const struct sockaddr *) &addr, sizeof(addr));
	ads->tcpsocket = fd;
	ads->tcpstate = server_connecting;
	if (r == 0) {
	    tcp_connected(ads, now);
	    return;
	}
	if (errno == EWOULDBLOCK || errno == EINPROGRESS) {
	    ads->tcptimeout = now;
	    timevaladd(&ads->tcptimeout, TCPCONNMS);
	    return;
	}
	adns__tcp_broken(ads, "connect", strerror(errno));
	ads->tcpstate = server_disconnected;
    }
}

/* Timeout handling functions. */

void adns__must_gettimeofday(adns_state ads, const struct timeval **now_io, struct timeval *tv_buf)
{
    const struct timeval *now;
    int r;

    now = *now_io;
    if (now)
	return;
    r = gettimeofday(tv_buf, 0);
    if (!r) {
	*now_io = tv_buf;
	return;
    }
    adns__diag(ads, -1, 0, "gettimeofday failed: %s", strerror(errno));
    adns_globalsystemfailure(ads);
    return;
}

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

    if (!tv_io)
	return;

    rbuf = *tv_io;
    if (!rbuf) {
	*tv_io = rbuf = tvbuf;
    }

    timerclear(rbuf);
}

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;
    } else {
	if (timercmp(rbuf, &maxto, >))
	    *rbuf = maxto;
    }
    /*fprintf(stderr,"inter_maxto maxto=%ld.%06ld result=%ld.%06ld\n",
     * maxto.tv_sec,maxto.tv_usec,(**tv_io).tv_sec,(**tv_io).tv_usec); */
}

static void inter_maxtoabs(struct timeval **tv_io, struct timeval *tvbuf,
			   struct timeval now, struct timeval maxtime)
{
    /* tv_io may be 0 */
    ldiv_t dr;

    /*fprintf(stderr,"inter_maxtoabs now=%ld.%06ld maxtime=%ld.%06ld\n",
     * now.tv_sec,now.tv_usec,maxtime.tv_sec,maxtime.tv_usec); */
    if (!tv_io)
	return;
    maxtime.tv_sec -= (now.tv_sec + 2);
    maxtime.tv_usec -= (now.tv_usec - 2000000);
    dr = ldiv(maxtime.tv_usec, 1000000);
    maxtime.tv_sec += dr.quot;
    maxtime.tv_usec -= dr.quot * 1000000;
    if (maxtime.tv_sec < 0)
	timerclear(&maxtime);
    inter_maxto(tv_io, tvbuf, maxtime);
}

static void timeouts_queue(adns_state ads, int act,
			   struct timeval **tv_io, struct timeval *tvbuf,
			   struct timeval now, struct query_queue *queue)
{
    adns_query qu, nqu;

    for (qu = queue->head; qu; qu = nqu) {
	nqu = qu->next;
	if (!timercmp(&now, &qu->timeout, >)) {
	    inter_maxtoabs(tv_io, tvbuf, now, qu->timeout);
	} else {
	    if (!act) {
		inter_immed(tv_io, tvbuf);
		return;
	    }
	    LIST_UNLINK(*queue, qu);
	    if (qu->state != query_tosend) {
		adns__query_fail(qu, adns_s_timeout);
	    } else {
		adns__query_send(qu, now);
	    }
	    nqu = queue->head;
	}
    }
}

static void tcp_events(adns_state ads, int act,
		       struct timeval **tv_io, struct timeval *tvbuf, struct timeval now)
{
    adns_query qu, nqu;

    for (;;) {
	switch (ads->tcpstate) {
	    case server_broken:
		if (!act) {
		    inter_immed(tv_io, tvbuf);
		    return;
		}
		for (qu = ads->tcpw.head; qu; qu = nqu) {
		    nqu = qu->next;
		    assert(qu->state == query_tcpw);
		    if (qu->retries > ads->nservers) {
			LIST_UNLINK(ads->tcpw, qu);
			adns__query_fail(qu, adns_s_allservfail);
		    }
		}
		ads->tcpstate = server_disconnected;
	    case server_disconnected:	/* fall through */
		if (!ads->tcpw.head)
		    return;
		if (!act) {
		    inter_immed(tv_io, tvbuf);
		    return;
		}
		adns__tcp_tryconnect(ads, now);
		break;
	    case server_ok:
		if (ads->tcpw.head)
		    return;
		if (!ads->tcptimeout.tv_sec) {
		    assert(!ads->tcptimeout.tv_usec);
		    ads->tcptimeout = now;
		    timevaladd(&ads->tcptimeout, TCPIDLEMS);
		}
	    case server_connecting:	/* fall through */
		if (!act || !timercmp(&now, &ads->tcptimeout, >)) {
		    inter_maxtoabs(tv_io, tvbuf, now, ads->tcptimeout);
		    return;
		}
		{
		    /* TCP timeout has happened */
		    switch (ads->tcpstate) {
			case server_connecting:	/* failed to connect */
			    adns__tcp_broken(ads, "unable to make connection", "timed out");
			    break;
			case server_ok:	/* idle timeout */
			    tcp_close(ads);
			    ads->tcpstate = server_disconnected;
			    return;
			default:
			    abort();
		    }
		}
		break;
	    default:
		abort();
	}
    }
    return;
}

void adns__timeouts(adns_state ads, int act,
		    struct timeval **tv_io, struct timeval *tvbuf, struct timeval now)
{
    timeouts_queue(ads, act, tv_io, tvbuf, now, &ads->udpw);
    timeouts_queue(ads, act, tv_io, tvbuf, now, &ads->tcpw);
    tcp_events(ads, act, tv_io, tvbuf, now);
}

void adns_firsttimeout(adns_state ads,
		       struct timeval **tv_io, struct timeval *tvbuf, struct timeval now)
{
    adns__consistency(ads, 0, cc_entex);
    adns__timeouts(ads, 0, tv_io, tvbuf, now);
    adns__consistency(ads, 0, cc_entex);
}

void adns_processtimeouts(adns_state ads, const struct timeval *now)
{
    struct timeval tv_buf;

    adns__consistency(ads, 0, cc_entex);
    adns__must_gettimeofday(ads, &now, &tv_buf);
    if (now)
	adns__timeouts(ads, 1, 0, 0, *now);
    adns__consistency(ads, 0, cc_entex);
}

/* fd handling functions.  These are the top-level of the real work of
 * reception and often transmission.
 */

int adns__pollfds(adns_state ads, struct adns_pollfd pollfds_buf[MAX_POLLFDS])
{
    /* Returns the number of entries filled in.  Always zeroes revents. */

    assert(MAX_POLLFDS == 2);

    pollfds_buf[0].fd = ads->udpsocket;
    pollfds_buf[0].events = ADNS_POLLIN;
    pollfds_buf[0].revents = 0;

    switch (ads->tcpstate) {
	case server_disconnected:
	case server_broken:
	    return 1;
	case server_connecting:
	    pollfds_buf[1].events = ADNS_POLLOUT;
	    break;
	case server_ok:
	    pollfds_buf[1].events =
		ads->tcpsend.
		used ? ADNS_POLLIN | ADNS_POLLOUT | ADNS_POLLPRI : ADNS_POLLIN | ADNS_POLLPRI;
	    break;
	default:
	    abort();
    }
    pollfds_buf[1].fd = ads->tcpsocket;
    return 2;
}

int adns_processreadable(adns_state ads, int fd, const struct timeval *now)
{
    int want, dgramlen, r, udpaddrlen, serv, old_skip;
    byte udpbuf[DNS_MAXUDP];
    struct sockaddr_in udpaddr;

    adns__consistency(ads, 0, cc_entex);

    switch (ads->tcpstate) {
	case server_disconnected:
	case server_broken:
	case server_connecting:
	    break;
	case server_ok:
	    if (fd != ads->tcpsocket)
		break;
	    assert(!ads->tcprecv_skip);
	    do {
		if (ads->tcprecv.used >= ads->tcprecv_skip + 2) {
		    dgramlen = ((ads->tcprecv.buf[ads->tcprecv_skip] << 8) |
				ads->tcprecv.buf[ads->tcprecv_skip + 1]);
		    if (ads->tcprecv.used >= ads->tcprecv_skip + 2 + dgramlen) {
			old_skip = ads->tcprecv_skip;
			ads->tcprecv_skip += 2 + dgramlen;
			adns__procdgram(ads, ads->tcprecv.buf + old_skip + 2,
					dgramlen, ads->tcpserver, 1, *now);
			continue;
		    } else {
			want = 2 + dgramlen;
		    }
		} else {
		    want = 2;
		}
		ads->tcprecv.used -= ads->tcprecv_skip;
		memmove(ads->tcprecv.buf, ads->tcprecv.buf + ads->tcprecv_skip, ads->tcprecv.used);
		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, (int *) &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",
			   inetntoa((char *) &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) {
		r = write(ads->tcpsocket, ads->tcpsend.buf, ads->tcpsend.used);
		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 adns_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;
	fd_event(ads, fd, revents, ADNS_POLLIN, maxfd, readfds, adns_processreadable, now, r_r);
	fd_event(ads, fd, revents, ADNS_POLLOUT, maxfd, writefds, adns_processwriteable, now, r_r);
	fd_event(ads, fd, revents, ADNS_POLLPRI, maxfd, exceptfds,
		 adns_processexceptional, now, r_r);
    }
}

/* Wrappers for select(2). */
#if 0
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 adns_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 & ADNS_POLLIN)
	    FD_SET(fd, readfds_io);
	if (pollfds[i].events & ADNS_POLLOUT)
	    FD_SET(fd, writefds_io);
	if (pollfds[i].events & ADNS_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 adns_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 = ADNS_POLLIN | ADNS_POLLOUT | ADNS_POLLPRI;
    adns__fdevents(ads, pollfds, npollfds, maxfd, readfds, writefds, exceptfds, *now, 0);
  xit:
    adns__consistency(ads, 0, cc_entex);
}
#endif
/* 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 adns_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 & ~ADNS_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;
    MyFree(qu);
    return 0;
}

#if 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;
}
#endif
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;
}