control.c

第二层隧道模块l2tp源码,开发环境为linux

#endif
        strncpy (ip1, IPADDY (c->lns->localaddr), sizeof (ip1));
        strncpy (ip2, IPADDY (c->addr), sizeof (ip2));
        po = NULL;
        po = add_opt (po, "passive");
        po = add_opt (po, "-detach");
        po = add_opt (po, "%s:%s", c->lns->localaddr ? ip1 : "", ip2);
        if (c->lns->authself)
        {
            if (c->lns->pap_refuse)
                po = add_opt (po, "refuse-pap");
            if (c->lns->chap_refuse)
                po = add_opt (po, "refuse-chap");
        }
        else
        {
            po = add_opt (po, "refuse-pap");
            po = add_opt (po, "refuse-chap");
        }
        if (c->lns->authpeer)
        {
            po = add_opt (po, "auth");
            if (c->lns->pap_require)
                po = add_opt (po, "require-pap");
            if (c->lns->chap_require)
                po = add_opt (po, "require-chap");
            if (c->lns->passwdauth)
                po = add_opt (po, "login");
        }
        if (c->lns->authname[0])
        {
            po = add_opt (po, "name");
            po = add_opt (po, c->lns->authname);
        }
        if (c->lns->debug)
            po = add_opt (po, "debug");
        if (c->lns->pppoptfile[0])
        {
            po = add_opt (po, "file");
            po = add_opt (po, c->lns->pppoptfile);
        }
        start_pppd (c, po);
        opt_destroy (po);
        log (LOG_LOG,
             "%s: Call established with %s, Local: %d, Remote: %d, Serial: %d\n",
             __FUNCTION__, IPADDY (t->peer.sin_addr), c->ourcid, c->cid,
             c->serno);
        break;
    case OCRP:                 /* jz: nothing to do for OCRP, waiting for OCCN */
        break;
    case OCCN:                 /* jz: get OCCN, so the only thing we must do is to start the pppd */
        po = NULL;
        po = add_opt (po, "passive");
        po = add_opt (po, "-detach");
        po = add_opt (po, "file");
        strcat (dummy_buf, c->dial_no); /* jz: use /etc/ppp/dialnumber.options for pppd - kick it if you dont like */
        strcat (dummy_buf, ".options");
        po = add_opt (po, dummy_buf);
        if (c->lac)
        {
            if (c->lac->defaultroute)
                po = add_opt (po, "defaultroute");
            strncpy (ip1, IPADDY (c->lac->localaddr), sizeof (ip1));
            strncpy (ip2, IPADDY (c->lac->remoteaddr), sizeof (ip2));
            po = add_opt (po, "%s:%s", c->lac->localaddr ? ip1 : "",
                          c->lac->remoteaddr ? ip2 : "");
            if (c->lac->authself)
            {
                if (c->lac->pap_refuse)
                    po = add_opt (po, "refuse-pap");
                if (c->lac->chap_refuse)
                    po = add_opt (po, "refuse-chap");
            }
            else
            {
                po = add_opt (po, "refuse-pap");
                po = add_opt (po, "refuse-chap");
            }
            if (c->lac->authpeer)
            {
                po = add_opt (po, "auth");
                if (c->lac->pap_require)
                    po = add_opt (po, "require-pap");
                if (c->lac->chap_require)
                    po = add_opt (po, "require-chap");
            }
            if (c->lac->authname[0])
            {
                po = add_opt (po, "name");
                po = add_opt (po, c->lac->authname);
            }
            if (c->lac->debug)
                po = add_opt (po, "debug");
            if (c->lac->pppoptfile[0])
            {
                po = add_opt (po, "file");
                po = add_opt (po, c->lac->pppoptfile);
            }
        };
        start_pppd (c, po);

        log (LOG_LOG, "parameters: Local: %d , Remote: %d , Serial: %d , Pid: %d , Tunnelid: %d , Phoneid: %s\n", c->ourcid, c->cid, c->serno, c->pppd, t->ourtid, c->dial_no); /*  jz: just show some information */

        opt_destroy (po);
        if (c->lac)
            c->lac->rtries = 0;
        break;


    case CDN:
        if (c->qcid < 0)
        {
            if (DEBUG)
                log (LOG_DEBUG,
                     "%s: Peer tried to disconnect without specifying call ID\n",
                     __FUNCTION__);
            return -EINVAL;
        }
        if (c == t->self)
        {
            p = t->call_head;
            while (p && (p->cid != c->qcid))
                p = p->next;
            if (!p)
            {
                if (DEBUG)
                    log (LOG_DEBUG,
                         "%s: Unable to determine call to be disconnected.\n",
                         __FUNCTION__);
                return -EINVAL;
            }
        }
        else
            p = c;
        if ((c->qcid != p->cid) && p->cid > 0)
        {
            if (DEBUG)
                log (LOG_DEBUG,
                     "%s: Peer tried to disconnect with invalid CID (%d != %d)\n",
                     __FUNCTION__, c->qcid, c->cid);
            return -EINVAL;
        }
        c->qcid = -1;
        if (c->result < 0)
        {
            if (DEBUG)
                log (LOG_DEBUG,
                     "%s: Peer tried to disconnect without specifying result code.\n",
                     __FUNCTION__);
            return -EINVAL;
        }
        log (LOG_LOG,
             "%s: Connection closed to %s, serial %d (%s)\n", __FUNCTION__,
             IPADDY (t->peer.sin_addr), c->serno, c->errormsg);
        c->needclose = 0;
        c->closing = -1;
        break;
    case Hello:
        break;
    case SLI:
        break;
    default:
        log (LOG_DEBUG,
             "%s: Don't know how to finish a message of type %d\n",
             __FUNCTION__, c->msgtype);
        set_error (c, VENDOR_ERROR, "Unimplemented message %d\n", c->msgtype);
    }
    return 0;
}

inline int check_control (const struct buffer *buf, struct tunnel *t,
                          struct call *c)
{
    /*
     * Check if this is a valid control
     * or not.  Returns 0 on success
     */
    struct control_hdr *h = (struct control_hdr *) (buf->start);
    struct buffer *zlb;
    if (buf->len < sizeof (struct control_hdr))
    {
        if (DEBUG)
        {
            log (LOG_DEBUG,
                 "%s: Received too small of packet\n", __FUNCTION__);
        }
        return -EINVAL;
    }
#ifdef SANITY
    if (buf->len != h->length)
    {
        if (DEBUG)
        {
            log (LOG_DEBUG,
                 "%s: Reported and actual sizes differ (%d != %d)\n",
                 __FUNCTION__, h->length, buf->len);
        }
        return -EINVAL;
    }
    /*
     * FIXME: H-bit handling goes here
     */
#ifdef DEBUG_CONTROL
    log (LOG_DEBUG, "%s: control, cid = %d, Ns = %d, Nr = %d\n", __FUNCTION__,
         c->cid, h->Ns, h->Nr);
#endif
    if (h->Ns != t->control_rec_seq_num)
    {
        if (DEBUG)
            log (LOG_DEBUG,
                 "%s: Received out of order control packet on tunnel %d (%d != %d)\n",
                 __FUNCTION__, t->tid, h->Ns, t->control_rec_seq_num);
        if (((h->Ns < t->control_rec_seq_num) && 
            ((t->control_rec_seq_num - h->Ns) < 32768)) ||
            ((h->Ns > t->control_rec_seq_num) &&
            ((t->control_rec_seq_num - h->Ns) > 32768)))
        {
            /*
               * Woopsies, they sent us a message we should have already received
               * so we should send them a ZLB so they know
               * for sure that we already have it.
             */
#ifdef DEBUG_ZLB
            if (DEBUG)
                log (LOG_DEBUG, "%s: Sending an updated ZLB in reponse\n",
                     __FUNCTION__);
#endif
            zlb = new_outgoing (t);
            control_zlb (zlb, t, c);
            udp_xmit (zlb);
            toss (zlb);
        }
        else if (!t->control_rec_seq_num && (t->tid == -1))
        {
            /* We made this tunnel just for this message, so let's
               destroy it.  */
            c->needclose = 0;
            c->closing = -1;
        }
        return -EINVAL;
    }
    else
    {
        t->control_rec_seq_num++;
        c->cnu = -1;
    }
    /*
     * So we know what the other end has received
     * so far
     */

    t->cLr = h->Nr;
    if (t->sanity)
    {
        if (!CTBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s: Control bit not set\n", __FUNCTION__);
            }
            return -EINVAL;
        }
        if (!CLBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s: Length bit not set\n", __FUNCTION__);
            }
            return -EINVAL;
        }
        if (!CFBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s: Flow bit not set\n", __FUNCTION__);
            }
            return -EINVAL;
        }
        if (CVER (h->ver) != VER_L2TP)
        {
            if (DEBUG)
            {
                if (CVER (h->ver) == VER_PPTP)
                {
                    log (LOG_DEBUG,
                         "%s: PPTP packet received\n", __FUNCTION__);
                }
                else if (CVER (h->ver) < VER_L2TP)
                {
                    log (LOG_DEBUG,
                         "%s: L2F packet received\n", __FUNCTION__);
                }
                else
                {
                    log (LOG_DEBUG,
                         "%s: Unknown version received\n", __FUNCTION__);
                }
            }
            return -EINVAL;
        }

    }
#endif
    return 0;
}

inline int check_payload (struct buffer *buf, struct tunnel *t,
                          struct call *c)
{
    /*
     * Check if this is a valid payload
     * or not.  Returns 0 on success.
     */

    int ehlen = MIN_PAYLOAD_HDR_LEN;
    struct payload_hdr *h = (struct payload_hdr *) (buf->start);
    if (!c)
    {
        if (DEBUG)
        {
            log (LOG_DEBUG, "%s: Aempted to send payload on tunnel\n",
                 __FUNCTION__);
        }
        return -EINVAL;
    }
    if (buf->len < MIN_PAYLOAD_HDR_LEN)
    {
        /* has to be at least MIN_PAYLOAD_HDR_LEN 
           no matter what.  we'll look more later */
        if (DEBUG)
        {
            log (LOG_DEBUG, "%s:Recieved to small of packet\n", __FUNCTION__);
        }
        return -EINVAL;
    }
#ifdef SANITY
    if (t->sanity)
    {
        if (PTBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s Control bit set\n", __FUNCTION__);
            }
            return -EINVAL;
        }
        if (PLBIT (h->ver))
            ehlen += 2;         /* Should have length information */
        if (PFBIT (h->ver))
        {
/*			if (!c->fbit && !c->ourfbit) {
				if (DEBUG)
					log(LOG_DEBUG,"%s: flow bit set, but no RWS negotiated.\n",__FUNCTION__);
				return -EINVAL;
			} */
            ehlen += 4;         /* Should have Ns and Nr too */
        }
/*		if (!PFBIT(h->ver)) {
			if (c->fbit || c->ourfbit) {
				if (DEBUG)
					log(LOG_DEBUG, "%s: no flow bit, but RWS was negotiated.\n",__FUNCTION__);
				return -EINVAL;;
			}
		} */
        if (PSBIT (h->ver))
            ehlen += 4;         /* Offset information */
        if (PLBIT (h->ver))
            ehlen += h->length; /* include length if available */
        if (PVER (h->ver) != VER_L2TP)
        {
            if (DEBUG)
            {
                if (PVER (h->ver) == VER_PPTP)
                {
                    log (LOG_DEBUG, "%s: PPTP packet received\n",
                         __FUNCTION__);
                }
                else if (CVER (h->ver) < VER_L2TP)
                {
                    log (LOG_DEBUG, "%s: L2F packet received\n",
                         __FUNCTION__);
                }
                else
                {
                    log (LOG_DEBUG, "%s: Unknown version received\n",
                         __FUNCTION__);
                }
            }
            return -EINVAL;
        }
        if ((buf->len < ehlen) && !PLBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s payload too small (%d < %d)\n",
                     __FUNCTION__, buf->len, ehlen);
            }
            return -EINVAL;
        }
        if ((buf->len != h->length) && PLBIT (h->ver))
        {
            if (DEBUG)
            {
                log (LOG_DEBUG, "%s: size mismatch (%d != %d)\n",
                     __FUNCTION__, buf->len, h->length);
            }
            return -EINVAL;
        }
    }
#endif
    return 0;
}
inline int expand_payload (struct buffer *buf, struct tunnel *t,
                           struct call *c)
{
    /*
     * Expands payload header.  Does not check for valid header,
     * check_payload() should already be called as a prerequisite.
     */
    struct payload_hdr *h = (struct payload_hdr *) (buf->start);
    _u16 *r = (_u16 *) h;       /* Nice to have raw word pointers */
    struct payload_hdr *new_hdr;
    int ehlen = 0;
    /*
     * We first calculate our offset
     */
    if (!PLBIT (h->ver))
        ehlen += 2;             /* Should have length information */
    if (!PFBIT (h->ver))
        ehlen += 4;             /* Should have Ns and Nr too */
    if (!PSBIT (h->ver))
        ehlen += 4;             /* Offset information */
    if (ehlen)
    {
        /*
         * If this payload is missing any information, we'll
         * fill it in
         */
        new_hdr = (struct payload_hdr *) (buf->start - ehlen);
        if ((void *) new_hdr < (void *) buf->rstart)
        {
            log (LOG_WARN, "%s: not enough space to decompress frame\n",
                 __FUNCTION__);
            return -EINVAL;

        };
        new_hdr->ver = *r;
        if (PLBIT (new_hdr->ver))
        {
            r++;
            new_hdr->length = *r;
        }
        else
        {