tcp.c

一款类linux的操作系统源码

/*
 *  Roadrunner/pk
 *    Copyright (C) 1989-2002  Cornfed Systems, Inc.
 *
 *  The Roadrunner/pk operating system is free software; you can
 *  redistribute and/or modify it under the terms of the GNU General
 *  Public License, version 2, as published by the Free Software
 *  Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT 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
 *
 *  More information about the Roadrunner/pk operating system of
 *  which this file is a part is available on the World-Wide Web
 *  at: http://www.cornfed.com.
 *
 */

#include <net/tcp.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/timer.h>

struct tcb tcbtab[TCP_CONNECTIONS];

void
tcp_init()
{
    bzero(tcbtab, TCP_CONNECTIONS * sizeof(struct tcb));
}

void
tcp_close(tcb_t tcb)
{
    socket_clear(tcb->socket);
    tcb_clear(tcb);
}

tcb_t
tcb_alloc(int state)
{
    tcb_t tcb;
    int i;

    for (i = 0; i < TCP_CONNECTIONS; i++) {
	tcb = &(tcbtab[i]);
	if (tcb->state == TCPS_CLOSED) {
	    tcb->state = state;
	    return tcb;
	}
    }
    return NULL;
}

void
tcb_clear(tcb_t tcb)
{
    bzero(tcb, sizeof(struct tcb));
}

tcb_t
tcb_find(ipaddr src, u_short sport,
	 ipaddr dst, u_short dport, int match_wildcards)
{
    socket_t socket;
    tcb_t match = NULL, tcb;
    int i, wildcards, wildcard_matches = 3;

    for (i = 0; i < TCP_CONNECTIONS; i++) {
	tcb = &(tcbtab[i]);
	socket = tcb->socket;

	if (socket == NULL)
	    continue;
	if (dport != socket->sport)
	    continue;
	wildcards = 0;

	if (dst == IP_ADDR_ANY) {
	    if (socket->src != IP_ADDR_ANY)
		wildcards++;
	} else {
	    if (socket->src == IP_ADDR_ANY)
		wildcards++;
	    else if (dst != socket->src)
		continue;
	}

	if (src == IP_ADDR_ANY) {
	    if (socket->dst != IP_ADDR_ANY)
		wildcards++;
	} else {
	    if (socket->dst == IP_ADDR_ANY)
		wildcards++;
	    else if (src != socket->dst || sport != socket->dport)
		continue;
	}
	if (wildcards > 0 && match_wildcards == 0)
	    continue;

	if (wildcards < wildcard_matches) {
	    match = tcb;
	    wildcard_matches = wildcards;
	    if (wildcard_matches == 0)
		break;
	}
    }
    return match;
}