/*
 * transmit.c
 * - construct queries
 * - send queries
 */
/*
 *  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: transmit.c,v 1.2 2003/06/14 13:55:50 tr-ircd Exp $
 */

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

#define MKQUERY_START(vb) (rqp= (vb)->buf+(vb)->used)
#define MKQUERY_ADDB(b) *rqp++= (b)
#define MKQUERY_ADDW(w) (MKQUERY_ADDB(((w)>>8)&0x0ff), MKQUERY_ADDB((w)&0x0ff))
#define MKQUERY_STOP(vb) ((vb)->used= rqp-(vb)->buf)

static adns_status mkquery_header(adns_state ads, vbuf * vb, int *id_r, int qdlen)
{
    int id;
    byte *rqp;

    if (!adns__vbuf_ensure(vb, DNS_HDRSIZE + qdlen + 4))
	return adns_s_nomemory;

    vb->used = 0;
    MKQUERY_START(vb);

    *id_r = id = (ads->nextid++) & 0x0ffff;
    MKQUERY_ADDW(id);
    MKQUERY_ADDB(0x01);		/* QR=Q(0), OPCODE=QUERY(0000), !AA, !TC, RD */
    MKQUERY_ADDB(0x00);		/* !RA, Z=000, RCODE=NOERROR(0000) */
    MKQUERY_ADDW(1);		/* QDCOUNT=1 */
    MKQUERY_ADDW(0);		/* ANCOUNT=0 */
    MKQUERY_ADDW(0);		/* NSCOUNT=0 */
    MKQUERY_ADDW(0);		/* ARCOUNT=0 */

    MKQUERY_STOP(vb);

    return adns_s_ok;
}

static adns_status mkquery_footer(vbuf * vb, adns_rrtype type)
{
byte *rqp;

    MKQUERY_START(vb);
    MKQUERY_ADDW(type & adns__rrt_typemask);	/* QTYPE */
    MKQUERY_ADDW(DNS_CLASS_IN);	/* QCLASS=IN */
    MKQUERY_STOP(vb);
    assert(vb->used <= vb->avail);

    return adns_s_ok;
}

adns_status adns__mkquery(adns_state ads, vbuf * vb, int *id_r,
			  const char *owner, int ol, const typeinfo * typei, adns_queryflags flags)
{
int ll, c, nbytes;
byte label[255], *rqp;
const char *p, *pe;
adns_status st;

    st = mkquery_header(ads, vb, id_r, ol + 2);
    if (st)
	return st;

    MKQUERY_START(vb);

    p = owner;
    pe = owner + ol;
    nbytes = 0;
    while (p != pe) {
	ll = 0;
	while (p != pe && (c = *p++) != '.') {
	    if (c == '\\') {
		if (!(flags & adns_qf_quoteok_query))
		    return adns_s_querydomaininvalid;
		if (ctype_digit(p[0])) {
		    if (ctype_digit(p[1]) && ctype_digit(p[2])) {
			c = (*p++ - '0') * 100;
			c += (*p++ - '0') * 10;
			c += (*p++ - '0');
			if (c >= 256)
			    return adns_s_querydomaininvalid;
		    } else {
			return adns_s_querydomaininvalid;
		    }
		} else if (!(c = *p++)) {
		    return adns_s_querydomaininvalid;
		}
	    }
	    if (!(flags & adns_qf_quoteok_query)) {
		if (c == '-') {
		    if (!ll)
			return adns_s_querydomaininvalid;
		} else if (!ctype_alpha(c) && !ctype_digit(c)) {
		    return adns_s_querydomaininvalid;
		}
	    }
	    if (ll == sizeof(label))
		return adns_s_querydomaininvalid;
	    label[ll++] = c;
	}
	if (!ll)
	    return adns_s_querydomaininvalid;
	if (ll > DNS_MAXLABEL)
	    return adns_s_querydomaintoolong;
	nbytes += ll + 1;
	if (nbytes >= DNS_MAXDOMAIN)
	    return adns_s_querydomaintoolong;
	MKQUERY_ADDB(ll);
	memcpy(rqp, label, ll);
	rqp += ll;
    }
    MKQUERY_ADDB(0);

    MKQUERY_STOP(vb);

    st = mkquery_footer(vb, typei->type);

    return adns_s_ok;
}

adns_status adns__mkquery_frdgram(adns_state ads, vbuf * vb, int *id_r,
				  const byte * qd_dgram, int qd_dglen,
				  int qd_begin, adns_rrtype type, adns_queryflags flags)
{
byte *rqp;
findlabel_state fls;
int lablen, labstart;
adns_status st;

    st = mkquery_header(ads, vb, id_r, qd_dglen);
    if (st)
	return st;

    MKQUERY_START(vb);

    adns__findlabel_start(&fls, ads, -1, 0, qd_dgram, qd_dglen, qd_dglen, qd_begin, 0);
    for (;;) {
	st = adns__findlabel_next(&fls, &lablen, &labstart);
	assert(!st);
	if (!lablen)
	    break;
	assert(lablen < 255);
	MKQUERY_ADDB(lablen);
	memcpy(rqp, qd_dgram + labstart, lablen);
	rqp += lablen;
    }
    MKQUERY_ADDB(0);

    MKQUERY_STOP(vb);

    st = mkquery_footer(vb, type);

    return adns_s_ok;
}

void adns__querysend_tcp(adns_query qu, struct timeval now)
{
    byte length[2];
#if 0
    struct iovec iov[2];
#endif
    int wr, wr2 = 0, r;
    adns_state ads;

    if (qu->ads->tcpstate != server_ok)
	return;

    assert(qu->state == query_tcpw);

    length[0] = (qu->query_dglen & 0x0ff00U) >> 8;
    length[1] = (qu->query_dglen & 0x0ff);

    ads = qu->ads;
    if (!adns__vbuf_ensure(&ads->tcpsend, ads->tcpsend.used + qu->query_dglen + 2))
	return;

    qu->retries++;

    /* Reset idle timeout. */
    ads->tcptimeout.tv_sec = ads->tcptimeout.tv_usec = 0;

    if (ads->tcpsend.used) {
	wr = 0;
    } else {
#if 0
	iov[0].iov_base = (char *) length;
	iov[0].iov_len = 2;
	iov[1].iov_base = (char *) qu->query_dgram;
	iov[1].iov_len = qu->query_dglen;
	wr = writev(qu->ads->tcpsocket, iov, 2);
#endif
	wr = write(qu->ads->tcpsocket, (char *) length, 2);
	if (wr > 0)
	    wr2 = write(qu->ads->tcpsocket, (char *) qu->query_dgram, qu->query_dglen);

	if (wr < 0 || wr2 < 0) {
	    if (!(errno == EAGAIN || errno == EINTR || errno == ENOSPC ||
		  errno == ENOBUFS || errno == ENOMEM)) {
		adns__tcp_broken(ads, "write", strerror(errno));
		return;
	    }
	    wr = 0;
	}
    }

    if (wr < 2) {
	r = adns__vbuf_append(&ads->tcpsend, length, 2 - wr);
	assert(r);
	wr = 0;
    } else {
	wr -= 2;
    }
    if (wr < qu->query_dglen) {
	r = adns__vbuf_append(&ads->tcpsend, qu->query_dgram + wr, qu->query_dglen - wr);
	assert(r);
    }
}

static void query_usetcp(adns_query qu, struct timeval now)
{
    qu->state = query_tcpw;
    qu->timeout = now;
    timevaladd(&qu->timeout, TCPWAITMS);
    LIST_LINK_TAIL(qu->ads->tcpw, qu);
    adns__querysend_tcp(qu, now);
    adns__tcp_tryconnect(qu->ads, now);
}

void adns__query_send(adns_query qu, struct timeval now)
{
    struct sockaddr_in servaddr;
    int serv, r;
    adns_state ads;

    assert(qu->state == query_tosend);
    if ((qu->flags & adns_qf_usevc) || (qu->query_dglen > DNS_MAXUDP)) {
	query_usetcp(qu, now);
	return;
    }

    if (qu->query_dglen > DNS_MAXUDP) {
        adns__query_fail(qu, adns_s_systemfail);
        return;
    }

    if (qu->retries >= UDPMAXRETRIES) {
	adns__query_fail(qu, adns_s_timeout);
	return;
    }

    serv = qu->udpnextserver;
    memset(&servaddr, 0, sizeof(servaddr));

    ads = qu->ads;
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr = ads->servers[serv].addr;
    servaddr.sin_port = htons(DNS_PORT);

    r = sendto(ads->udpsocket, qu->query_dgram, qu->query_dglen, 0,
	       (const struct sockaddr *) &servaddr, sizeof(servaddr));
    if (r < 0 && errno == EMSGSIZE) {
	qu->retries = 0;
	query_usetcp(qu, now);
	return;
    }
    if (r < 0 && errno != EAGAIN)
	adns__warn(ads, serv, 0, "sendto failed: %s", strerror(errno));

    qu->timeout = now;
    timevaladd(&qu->timeout, UDPRETRYMS);
    qu->udpsent |= (1 << serv);
    qu->udpnextserver = (serv + 1) % ads->nservers;
    qu->retries++;
    LIST_LINK_TAIL(ads->udpw, qu);
}