call.c

第二层隧道模块l2tp源码,开发环境为linux

/*
 * Layer Two Tunnelling Protocol Daemon
 * Copyright (C) 1998 Adtran, Inc.
 * Copyright (C) 2002 Jeff McAdams
 *
 * Mark Spencer
 *
 * This software is distributed under the terms
 * of the GPL, which you should have received
 * along with this source.
 *
 * Handle a call as a separate thread
 */

#include <stdio.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <termios.h>
#include "l2tp.h"
#ifdef USE_KERNEL
#include <sys/ioctl.h>
#endif

struct buffer *new_payload (struct sockaddr_in peer)
{
    struct buffer *tmp = new_buf (MAX_RECV_SIZE);
    if (!tmp)
        return NULL;
    tmp->peer = peer;
    tmp->start += sizeof (struct payload_hdr);
    tmp->len = 0;
    return tmp;
}

inline void recycle_payload (struct buffer *buf, struct sockaddr_in peer)
{
    buf->start = buf->rstart + sizeof (struct payload_hdr);
    buf->len = 0;
    buf->peer = peer;
}

void add_payload_hdr (struct tunnel *t, struct call *c, struct buffer *buf)
{
    struct payload_hdr *p;
    buf->start -= sizeof (struct payload_hdr);
    buf->len += sizeof (struct payload_hdr);
    /* Account for no offset */
    buf->start += 4;
    buf->len -= 4;
    if (!c->fbit && !c->ourfbit)
    {
        /* Forget about Ns and Nr fields then */
        buf->start += 4;
        buf->len -= 4;
    }
    if (!c->lbit)
    {
        /* Forget about specifying the length */
        buf->start += 2;
        buf->len -= 2;
    }
    p = (struct payload_hdr *) buf->start;
/*	p->ver = htons(c->lbit | c->rbit | c->fbit | c->ourfbit | VER_L2TP); */
    p->ver = htons (c->lbit | c->fbit | c->ourfbit | VER_L2TP);
    if (c->lbit)
    {
        p->length = htons ((_u16) buf->len);
    }
    else
    {
        p = (struct payload_hdr *) (((char *) p) - 2);
    }
    p->tid = htons (t->tid);
    p->cid = htons (c->cid);
    if (c->fbit || c->ourfbit)
    {
        p->Ns = htons (c->data_seq_num);
        p->Nr = htons (c->data_rec_seq_num);
    }
    c->data_seq_num++;
/*	c->rbit=0; */
}

int read_packet (struct buffer *buf, int fd, int convert)
{
    unsigned char c;
    unsigned char escape = 0;
    unsigned char *p;
    static unsigned char rbuf[MAX_RECV_SIZE];
    static int pos = 0;
    static int max = 0;
    int res;
    int errors = 0;
    /* Read a packet, doing async->sync conversion if necessary */
    p = buf->start;
    while (1)
    {
        if (pos >= max)
        {
            max = read (fd, rbuf, sizeof (rbuf));
            res = max;
            pos = 0;
        }
        else
        {
            res = 1;
        }
        c = rbuf[pos++];
        if (res < 1)
        {
            if (res == 0)
            {
                /*
                   * Hmm..  Nothing to read.  It happens
                 */
                return 0;
/*			} else if ((errno == EINTR ) || (errno == EAGAIN)) { */
            }
            else if ((errno == EIO) || (errno == EINTR) || (errno == EAGAIN))
            {

                /*
                   * Oops, we were interrupted!
                   * Or, we ran out of data too soon
                   * anyway, we discared whatever it is we
                   * have
                 */
                return 0;
            }
            errors++;
            log (LOG_DEBUG, "%s: Error %d (%s)\n", __FUNCTION__, errno,
                 strerror (errno));
            if (errors > 10)
            {
                log (LOG_DEBUG,
                     "%s: Too many errors.  Declaring call dead.\n",
                     __FUNCTION__);
                return -errno;
            }
            continue;
        }
        switch (c)
        {
        case PPP_FLAG:
            if (escape)
            {
                log (LOG_DEBUG, "%s: got an escaped PPP_FLAG\n",
                     __FUNCTION__);
                return -EINVAL;
            }
            if (convert)
            {
                if (!buf->len)
                    break;
                /* Drop the FCS */
                buf->len -= 2;
            }
            else
            {
                if (buf->len < buf->maxlen)
                {
                    *p = c;
                    p++;
                    buf->len++;
                }
            }
            return buf->len;
        case PPP_ESCAPE:
            escape = PPP_TRANS;
            if (convert)
                break;
        default:
            if (convert)
                c ^= escape;
            escape = 0;
            if (buf->len < buf->maxlen)
            {
                *p = c;
                p++;
                buf->len++;
                break;
            };
            log (LOG_WARN, "%s: read overrun\n", __FUNCTION__);
            return -EINVAL;
        }
    }
    /* I should never get here */
    log (LOG_WARN, "%s: You should not see this message.  If you do, please
		       enter a bug report at http://sourceforge.net/projects/l2tpd", __FUNCTION__);
    return -EINVAL;
}

void call_close (struct call *c)
{
    struct buffer *buf;
    struct schedule_entry *se, *ose;
    struct call *tmp, *tmp2;
    if (!c || !c->container)
    {
        log (LOG_DEBUG, "%s: called on null call or containerless call\n",
             __FUNCTION__);
        return;
    }
    if (c == c->container->self)
    {
        /*
         * We're actually closing the
         * entire tunnel
         */

        /* First deschedule any remaining packet transmissions
           for this tunnel.  That means Hello's and any reminaing
           packets scheduled for transmission.  This is a very
           nasty little piece of code here. */

        se = events;
        ose = NULL;
        while (se)
        {
            if ((((struct buffer *) se->data)->tunnel == c->container)
                || ((struct tunnel *) se->data == c->container))
            {
#ifdef DEBUG_CLOSE
                log (LOG_DEBUG, "%s: Descheduling event\n", __FUNCTION__);
#endif
                if (ose)
                {
                    ose->next = se->next;
                    if ((struct tunnel *) se->data != c->container)
                        toss ((struct buffer *) (se->data));
                    free (se);
                    se = ose->next;
                }
                else
                {
                    events = se->next;
                    if ((struct tunnel *) se->data != c->container)
                        toss ((struct buffer *) (se->data));
                    free (se);
                    se = events;
                }
            }
            else
            {
                ose = se;
                se = se->next;
            }
        }

        if (c->closing)
        {
            /* Really close this tunnel, as our
               StopCCN has been ack'd */
#ifdef DEBUG_CLOSE
            log (LOG_DEBUG, "%s: Actually closing tunnel %d\n", __FUNCTION__,
                 c->container->ourtid);
#endif
#ifdef USE_KERNEL
            if (kernel_support)
                ioctl (server_socket, L2TPIOCDELTUNNEL, c->container->ourtid);
#endif
            destroy_tunnel (c->container);
            return;
        }

        /*
           * We need to close, but need to provide reliable delivery
           * of the final StopCCN. We record our state to know when
           * we have actually received an ACK on our StopCCN
         */
        c->closeSs = c->container->control_seq_num;
        buf = new_outgoing (c->container);
        add_message_type_avp (buf, StopCCN);
        if (c->container->hbit)
        {
            mk_challenge (c->container->chal_them.vector, VECTOR_SIZE);
            add_randvect_avp (buf, c->container->chal_them.vector,
                              VECTOR_SIZE);
        }
        add_tunnelid_avp (buf, c->container->ourtid);
        if (c->result < 0)
            c->result = RESULT_CLEAR;
        if (c->error < 0)
            c->error = 0;
        add_result_code_avp (buf, c->result, c->error, c->errormsg,
                             strlen (c->errormsg));
        add_control_hdr (c->container, c, buf);
        if (packet_dump)
            do_packet_dump (buf);
#ifdef DEBUG_CLOSE
        log (LOG_DEBUG, "%s: enqueing close message for tunnel\n",
             __FUNCTION__);
#endif
        control_xmit (buf);
        /*
           * We also need to stop all traffic on any calls contained
           * within us.
         */
        tmp = c->container->call_head;
        while (tmp)
        {
            tmp2 = tmp->next;
            tmp->needclose = 0;
            tmp->closing = -1;
            call_close (tmp);
            tmp = tmp2;
        }
        log (LOG_LOG,
             "%s : Connection %d closed to %s, port %d (%s)\n", __FUNCTION__,
             c->container->tid,
             IPADDY (c->container->peer.sin_addr),
             ntohs (c->container->peer.sin_port), c->errormsg);
    }
    else
    {
        /*
           * Just close a call
         */
#ifdef USE_KERNEL
        struct l2tp_call_opts co;
#endif
        if (c->zlb_xmit)
            deschedule (c->zlb_xmit);
/*		if (c->dethrottle) deschedule(c->dethrottle); */
        if (c->closing)
        {
#ifdef DEBUG_CLOSE
            log (LOG_DEBUG, "%s: Actually closing call %d\n", __FUNCTION__,
                 c->ourcid);
#endif