Linux 2.6.20.7

[linux/fpc-iii.git] / drivers / net / wan / syncppp.c

/*
 *      NET3:   A (fairly minimal) implementation of synchronous PPP for Linux
 *              as well as a CISCO HDLC implementation. See the copyright 
 *              message below for the original source.
 *
 *      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 of the license, or (at your option) any later version.
 *
 *      Note however. This code is also used in a different form by FreeBSD.
 *      Therefore when making any non OS specific change please consider
 *      contributing it back to the original author under the terms
 *      below in addition.
 *              -- Alan
 *
 *      Port for Linux-2.1 by Jan "Yenya" Kasprzak <kas@fi.muni.cz>
 */

/*
 * Synchronous PPP/Cisco link level subroutines.
 * Keepalive protocol implemented in both Cisco and PPP modes.
 *
 * Copyright (C) 1994 Cronyx Ltd.
 * Author: Serge Vakulenko, <vak@zebub.msk.su>
 *
 * This software is distributed with NO WARRANTIES, not even the implied
 * warranties for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Authors grant any other persons or organisations permission to use
 * or modify this software as long as this message is kept with the software,
 * all derivative works or modified versions.
 *
 * Version 1.9, Wed Oct  4 18:58:15 MSK 1995
 *
 * $Id: syncppp.c,v 1.18 2000/04/11 05:25:31 asj Exp $
 */
#undef DEBUG

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/route.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/random.h>
#include <linux/pkt_sched.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>

#include <net/syncppp.h>

#include <asm/byteorder.h>
#include <asm/uaccess.h>

#define MAXALIVECNT     6               /* max. alive packets */

#define PPP_ALLSTATIONS 0xff            /* All-Stations broadcast address */
#define PPP_UI          0x03            /* Unnumbered Information */
#define PPP_IP          0x0021          /* Internet Protocol */
#define PPP_ISO         0x0023          /* ISO OSI Protocol */
#define PPP_XNS         0x0025          /* Xerox NS Protocol */
#define PPP_IPX         0x002b          /* Novell IPX Protocol */
#define PPP_LCP         0xc021          /* Link Control Protocol */
#define PPP_IPCP        0x8021          /* Internet Protocol Control Protocol */

#define LCP_CONF_REQ    1               /* PPP LCP configure request */
#define LCP_CONF_ACK    2               /* PPP LCP configure acknowledge */
#define LCP_CONF_NAK    3               /* PPP LCP configure negative ack */
#define LCP_CONF_REJ    4               /* PPP LCP configure reject */
#define LCP_TERM_REQ    5               /* PPP LCP terminate request */
#define LCP_TERM_ACK    6               /* PPP LCP terminate acknowledge */
#define LCP_CODE_REJ    7               /* PPP LCP code reject */
#define LCP_PROTO_REJ   8               /* PPP LCP protocol reject */
#define LCP_ECHO_REQ    9               /* PPP LCP echo request */
#define LCP_ECHO_REPLY  10              /* PPP LCP echo reply */
#define LCP_DISC_REQ    11              /* PPP LCP discard request */

#define LCP_OPT_MRU             1       /* maximum receive unit */
#define LCP_OPT_ASYNC_MAP       2       /* async control character map */
#define LCP_OPT_AUTH_PROTO      3       /* authentication protocol */
#define LCP_OPT_QUAL_PROTO      4       /* quality protocol */
#define LCP_OPT_MAGIC           5       /* magic number */
#define LCP_OPT_RESERVED        6       /* reserved */
#define LCP_OPT_PROTO_COMP      7       /* protocol field compression */
#define LCP_OPT_ADDR_COMP       8       /* address/control field compression */

#define IPCP_CONF_REQ   LCP_CONF_REQ    /* PPP IPCP configure request */
#define IPCP_CONF_ACK   LCP_CONF_ACK    /* PPP IPCP configure acknowledge */
#define IPCP_CONF_NAK   LCP_CONF_NAK    /* PPP IPCP configure negative ack */
#define IPCP_CONF_REJ   LCP_CONF_REJ    /* PPP IPCP configure reject */
#define IPCP_TERM_REQ   LCP_TERM_REQ    /* PPP IPCP terminate request */
#define IPCP_TERM_ACK   LCP_TERM_ACK    /* PPP IPCP terminate acknowledge */
#define IPCP_CODE_REJ   LCP_CODE_REJ    /* PPP IPCP code reject */

#define CISCO_MULTICAST         0x8f    /* Cisco multicast address */
#define CISCO_UNICAST           0x0f    /* Cisco unicast address */
#define CISCO_KEEPALIVE         0x8035  /* Cisco keepalive protocol */
#define CISCO_ADDR_REQ          0       /* Cisco address request */
#define CISCO_ADDR_REPLY        1       /* Cisco address reply */
#define CISCO_KEEPALIVE_REQ     2       /* Cisco keepalive request */

struct ppp_header {
        u8 address;
        u8 control;
        u16 protocol;
};
#define PPP_HEADER_LEN          sizeof (struct ppp_header)

struct lcp_header {
        u8 type;
        u8 ident;
        u16 len;
};
#define LCP_HEADER_LEN          sizeof (struct lcp_header)

struct cisco_packet {
        u32 type;
        u32 par1;
        u32 par2;
        u16 rel;
        u16 time0;
        u16 time1;
};
#define CISCO_PACKET_LEN 18
#define CISCO_BIG_PACKET_LEN 20

static struct sppp *spppq;
static struct timer_list sppp_keepalive_timer;
static DEFINE_SPINLOCK(spppq_lock);

/* global xmit queue for sending packets while spinlock is held */
static struct sk_buff_head tx_queue;

static void sppp_keepalive (unsigned long dummy);
static void sppp_cp_send (struct sppp *sp, u16 proto, u8 type,
        u8 ident, u16 len, void *data);
static void sppp_cisco_send (struct sppp *sp, int type, long par1, long par2);
static void sppp_lcp_input (struct sppp *sp, struct sk_buff *m);
static void sppp_cisco_input (struct sppp *sp, struct sk_buff *m);
static void sppp_ipcp_input (struct sppp *sp, struct sk_buff *m);
static void sppp_lcp_open (struct sppp *sp);
static void sppp_ipcp_open (struct sppp *sp);
static int sppp_lcp_conf_parse_options (struct sppp *sp, struct lcp_header *h,
        int len, u32 *magic);
static void sppp_cp_timeout (unsigned long arg);
static char *sppp_lcp_type_name (u8 type);
static char *sppp_ipcp_type_name (u8 type);
static void sppp_print_bytes (u8 *p, u16 len);

static int debug;

/* Flush global outgoing packet queue to dev_queue_xmit().
 *
 * dev_queue_xmit() must be called with interrupts enabled
 * which means it can't be called with spinlocks held.
 * If a packet needs to be sent while a spinlock is held,
 * then put the packet into tx_queue, and call sppp_flush_xmit()
 * after spinlock is released.
 */
static void sppp_flush_xmit(void)
{
        struct sk_buff *skb;
        while ((skb = skb_dequeue(&tx_queue)) != NULL)
                dev_queue_xmit(skb);
}

/*
 *      Interface down stub
 */     

static void if_down(struct net_device *dev)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);

        sp->pp_link_state=SPPP_LINK_DOWN;
}

/*
 * Timeout routine activations.
 */

static void sppp_set_timeout(struct sppp *p,int s) 
{
        if (! (p->pp_flags & PP_TIMO)) 
        {
                init_timer(&p->pp_timer);
                p->pp_timer.function=sppp_cp_timeout;
                p->pp_timer.expires=jiffies+s*HZ;
                p->pp_timer.data=(unsigned long)p;
                p->pp_flags |= PP_TIMO;
                add_timer(&p->pp_timer);
        }
}

static void sppp_clear_timeout(struct sppp *p)
{
        if (p->pp_flags & PP_TIMO) 
        {
                del_timer(&p->pp_timer);
                p->pp_flags &= ~PP_TIMO; 
        }
}

/**
 *      sppp_input -    receive and process a WAN PPP frame
 *      @skb:   The buffer to process
 *      @dev:   The device it arrived on
 *
 *      This can be called directly by cards that do not have
 *      timing constraints but is normally called from the network layer
 *      after interrupt servicing to process frames queued via netif_rx().
 *
 *      We process the options in the card. If the frame is destined for
 *      the protocol stacks then it requeues the frame for the upper level
 *      protocol. If it is a control from it is processed and discarded
 *      here.
 */
 
static void sppp_input (struct net_device *dev, struct sk_buff *skb)
{
        struct ppp_header *h;
        struct sppp *sp = (struct sppp *)sppp_of(dev);
        unsigned long flags;

        skb->dev=dev;
        skb->mac.raw=skb->data;

        if (dev->flags & IFF_RUNNING)
        {
                /* Count received bytes, add FCS and one flag */
                sp->ibytes+= skb->len + 3;
                sp->ipkts++;
        }

        if (!pskb_may_pull(skb, PPP_HEADER_LEN)) {
                /* Too small packet, drop it. */
                if (sp->pp_flags & PP_DEBUG)
                        printk (KERN_DEBUG "%s: input packet is too small, %d bytes\n",
                                dev->name, skb->len);
                kfree_skb(skb);
                return;
        }

        /* Get PPP header. */
        h = (struct ppp_header *)skb->data;
        skb_pull(skb,sizeof(struct ppp_header));

        spin_lock_irqsave(&sp->lock, flags);
        
        switch (h->address) {
        default:        /* Invalid PPP packet. */
                goto invalid;
        case PPP_ALLSTATIONS:
                if (h->control != PPP_UI)
                        goto invalid;
                if (sp->pp_flags & PP_CISCO) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: PPP packet in Cisco mode <0x%x 0x%x 0x%x>\n",
                                        dev->name,
                                        h->address, h->control, ntohs (h->protocol));
                        goto drop;
                }
                switch (ntohs (h->protocol)) {
                default:
                        if (sp->lcp.state == LCP_STATE_OPENED)
                                sppp_cp_send (sp, PPP_LCP, LCP_PROTO_REJ,
                                        ++sp->pp_seq, skb->len + 2,
                                        &h->protocol);
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: invalid input protocol <0x%x 0x%x 0x%x>\n",
                                        dev->name,
                                        h->address, h->control, ntohs (h->protocol));
                        goto drop;
                case PPP_LCP:
                        sppp_lcp_input (sp, skb);
                        goto drop;
                case PPP_IPCP:
                        if (sp->lcp.state == LCP_STATE_OPENED)
                                sppp_ipcp_input (sp, skb);
                        else
                                printk(KERN_DEBUG "IPCP when still waiting LCP finish.\n");
                        goto drop;
                case PPP_IP:
                        if (sp->ipcp.state == IPCP_STATE_OPENED) {
                                if(sp->pp_flags&PP_DEBUG)
                                        printk(KERN_DEBUG "Yow an IP frame.\n");
                                skb->protocol=htons(ETH_P_IP);
                                netif_rx(skb);
                                dev->last_rx = jiffies;
                                goto done;
                        }
                        break;
#ifdef IPX
                case PPP_IPX:
                        /* IPX IPXCP not implemented yet */
                        if (sp->lcp.state == LCP_STATE_OPENED) {
                                skb->protocol=htons(ETH_P_IPX);
                                netif_rx(skb);
                                dev->last_rx = jiffies;
                                goto done;
                        }
                        break;
#endif
                }
                break;
        case CISCO_MULTICAST:
        case CISCO_UNICAST:
                /* Don't check the control field here (RFC 1547). */
                if (! (sp->pp_flags & PP_CISCO)) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: Cisco packet in PPP mode <0x%x 0x%x 0x%x>\n",
                                        dev->name,
                                        h->address, h->control, ntohs (h->protocol));
                        goto drop;
                }
                switch (ntohs (h->protocol)) {
                default:
                        goto invalid;
                case CISCO_KEEPALIVE:
                        sppp_cisco_input (sp, skb);
                        goto drop;
#ifdef CONFIG_INET
                case ETH_P_IP:
                        skb->protocol=htons(ETH_P_IP);
                        netif_rx(skb);
                        dev->last_rx = jiffies;
                        goto done;
#endif
#ifdef CONFIG_IPX
                case ETH_P_IPX:
                        skb->protocol=htons(ETH_P_IPX);
                        netif_rx(skb);
                        dev->last_rx = jiffies;
                        goto done;
#endif
                }
                break;
        }
        goto drop;

invalid:
        if (sp->pp_flags & PP_DEBUG)
                printk (KERN_WARNING "%s: invalid input packet <0x%x 0x%x 0x%x>\n",
                        dev->name, h->address, h->control, ntohs (h->protocol));
drop:
        kfree_skb(skb);
done:
        spin_unlock_irqrestore(&sp->lock, flags);
        sppp_flush_xmit();
        return;
}

/*
 *      Handle transmit packets.
 */
 
static int sppp_hard_header(struct sk_buff *skb, struct net_device *dev, __u16 type,
                void *daddr, void *saddr, unsigned int len)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);
        struct ppp_header *h;
        skb_push(skb,sizeof(struct ppp_header));
        h=(struct ppp_header *)skb->data;
        if(sp->pp_flags&PP_CISCO)
        {
                h->address = CISCO_UNICAST;
                h->control = 0;
        }
        else
        {
                h->address = PPP_ALLSTATIONS;
                h->control = PPP_UI;
        }
        if(sp->pp_flags & PP_CISCO)
        {
                h->protocol = htons(type);
        }
        else switch(type)
        {
                case ETH_P_IP:
                        h->protocol = htons(PPP_IP);
                        break;
                case ETH_P_IPX:
                        h->protocol = htons(PPP_IPX);
                        break;
        }
        return sizeof(struct ppp_header);
}

static int sppp_rebuild_header(struct sk_buff *skb)
{
        return 0;
}

/*
 * Send keepalive packets, every 10 seconds.
 */

static void sppp_keepalive (unsigned long dummy)
{
        struct sppp *sp;
        unsigned long flags;

        spin_lock_irqsave(&spppq_lock, flags);

        for (sp=spppq; sp; sp=sp->pp_next) 
        {
                struct net_device *dev = sp->pp_if;

                /* Keepalive mode disabled or channel down? */
                if (! (sp->pp_flags & PP_KEEPALIVE) ||
                    ! (dev->flags & IFF_UP))
                        continue;

                spin_lock(&sp->lock);

                /* No keepalive in PPP mode if LCP not opened yet. */
                if (! (sp->pp_flags & PP_CISCO) &&
                    sp->lcp.state != LCP_STATE_OPENED) {
                        spin_unlock(&sp->lock);
                        continue;
                }

                if (sp->pp_alivecnt == MAXALIVECNT) {
                        /* No keepalive packets got.  Stop the interface. */
                        printk (KERN_WARNING "%s: protocol down\n", dev->name);
                        if_down (dev);
                        if (! (sp->pp_flags & PP_CISCO)) {
                                /* Shut down the PPP link. */
                                sp->lcp.magic = jiffies;
                                sp->lcp.state = LCP_STATE_CLOSED;
                                sp->ipcp.state = IPCP_STATE_CLOSED;
                                sppp_clear_timeout (sp);
                                /* Initiate negotiation. */
                                sppp_lcp_open (sp);
                        }
                }
                if (sp->pp_alivecnt <= MAXALIVECNT)
                        ++sp->pp_alivecnt;
                if (sp->pp_flags & PP_CISCO)
                        sppp_cisco_send (sp, CISCO_KEEPALIVE_REQ, ++sp->pp_seq,
                                sp->pp_rseq);
                else if (sp->lcp.state == LCP_STATE_OPENED) {
                        long nmagic = htonl (sp->lcp.magic);
                        sp->lcp.echoid = ++sp->pp_seq;
                        sppp_cp_send (sp, PPP_LCP, LCP_ECHO_REQ,
                                sp->lcp.echoid, 4, &nmagic);
                }

                spin_unlock(&sp->lock);
        }
        spin_unlock_irqrestore(&spppq_lock, flags);
        sppp_flush_xmit();
        sppp_keepalive_timer.expires=jiffies+10*HZ;
        add_timer(&sppp_keepalive_timer);
}

/*
 * Handle incoming PPP Link Control Protocol packets.
 */
 
static void sppp_lcp_input (struct sppp *sp, struct sk_buff *skb)
{
        struct lcp_header *h;
        struct net_device *dev = sp->pp_if;
        int len = skb->len;
        u8 *p, opt[6];
        u32 rmagic = 0;

        if (!pskb_may_pull(skb, sizeof(struct lcp_header))) {
                if (sp->pp_flags & PP_DEBUG)
                        printk (KERN_WARNING "%s: invalid lcp packet length: %d bytes\n",
                                dev->name, len);
                return;
        }
        h = (struct lcp_header *)skb->data;
        skb_pull(skb,sizeof(struct lcp_header *));
        
        if (sp->pp_flags & PP_DEBUG) 
        {
                char state = '?';
                switch (sp->lcp.state) {
                case LCP_STATE_CLOSED:   state = 'C'; break;
                case LCP_STATE_ACK_RCVD: state = 'R'; break;
                case LCP_STATE_ACK_SENT: state = 'S'; break;
                case LCP_STATE_OPENED:   state = 'O'; break;
                }
                printk (KERN_WARNING "%s: lcp input(%c): %d bytes <%s id=%xh len=%xh",
                        dev->name, state, len,
                        sppp_lcp_type_name (h->type), h->ident, ntohs (h->len));
                if (len > 4)
                        sppp_print_bytes ((u8*) (h+1), len-4);
                printk (">\n");
        }
        if (len > ntohs (h->len))
                len = ntohs (h->len);
        switch (h->type) {
        default:
                /* Unknown packet type -- send Code-Reject packet. */
                sppp_cp_send (sp, PPP_LCP, LCP_CODE_REJ, ++sp->pp_seq,
                        skb->len, h);
                break;
        case LCP_CONF_REQ:
                if (len < 4) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_DEBUG"%s: invalid lcp configure request packet length: %d bytes\n",
                                        dev->name, len);
                        break;
                }
                if (len>4 && !sppp_lcp_conf_parse_options (sp, h, len, &rmagic))
                        goto badreq;
                if (rmagic == sp->lcp.magic) {
                        /* Local and remote magics equal -- loopback? */
                        if (sp->pp_loopcnt >= MAXALIVECNT*5) {
                                printk (KERN_WARNING "%s: loopback\n",
                                        dev->name);
                                sp->pp_loopcnt = 0;
                                if (dev->flags & IFF_UP) {
                                        if_down (dev);
                                }
                        } else if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_DEBUG "%s: conf req: magic glitch\n",
                                        dev->name);
                        ++sp->pp_loopcnt;

                        /* MUST send Conf-Nack packet. */
                        rmagic = ~sp->lcp.magic;
                        opt[0] = LCP_OPT_MAGIC;
                        opt[1] = sizeof (opt);
                        opt[2] = rmagic >> 24;
                        opt[3] = rmagic >> 16;
                        opt[4] = rmagic >> 8;
                        opt[5] = rmagic;
                        sppp_cp_send (sp, PPP_LCP, LCP_CONF_NAK,
                                h->ident, sizeof (opt), &opt);
badreq:
                        switch (sp->lcp.state) {
                        case LCP_STATE_OPENED:
                                /* Initiate renegotiation. */
                                sppp_lcp_open (sp);
                                /* fall through... */
                        case LCP_STATE_ACK_SENT:
                                /* Go to closed state. */
                                sp->lcp.state = LCP_STATE_CLOSED;
                                sp->ipcp.state = IPCP_STATE_CLOSED;
                        }
                        break;
                }
                /* Send Configure-Ack packet. */
                sp->pp_loopcnt = 0;
                if (sp->lcp.state != LCP_STATE_OPENED) {
                        sppp_cp_send (sp, PPP_LCP, LCP_CONF_ACK,
                                        h->ident, len-4, h+1);
                }
                /* Change the state. */
                switch (sp->lcp.state) {
                case LCP_STATE_CLOSED:
                        sp->lcp.state = LCP_STATE_ACK_SENT;
                        break;
                case LCP_STATE_ACK_RCVD:
                        sp->lcp.state = LCP_STATE_OPENED;
                        sppp_ipcp_open (sp);
                        break;
                case LCP_STATE_OPENED:
                        /* Remote magic changed -- close session. */
                        sp->lcp.state = LCP_STATE_CLOSED;
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                        /* Initiate renegotiation. */
                        sppp_lcp_open (sp);
                        /* Send ACK after our REQ in attempt to break loop */
                        sppp_cp_send (sp, PPP_LCP, LCP_CONF_ACK,
                                        h->ident, len-4, h+1);
                        sp->lcp.state = LCP_STATE_ACK_SENT;
                        break;
                }
                break;
        case LCP_CONF_ACK:
                if (h->ident != sp->lcp.confid)
                        break;
                sppp_clear_timeout (sp);
                if ((sp->pp_link_state != SPPP_LINK_UP) &&
                    (dev->flags & IFF_UP)) {
                        /* Coming out of loopback mode. */
                        sp->pp_link_state=SPPP_LINK_UP;
                        printk (KERN_INFO "%s: protocol up\n", dev->name);
                }
                switch (sp->lcp.state) {
                case LCP_STATE_CLOSED:
                        sp->lcp.state = LCP_STATE_ACK_RCVD;
                        sppp_set_timeout (sp, 5);
                        break;
                case LCP_STATE_ACK_SENT:
                        sp->lcp.state = LCP_STATE_OPENED;
                        sppp_ipcp_open (sp);
                        break;
                }
                break;
        case LCP_CONF_NAK:
                if (h->ident != sp->lcp.confid)
                        break;
                p = (u8*) (h+1);
                if (len>=10 && p[0] == LCP_OPT_MAGIC && p[1] >= 4) {
                        rmagic = (u32)p[2] << 24 |
                                (u32)p[3] << 16 | p[4] << 8 | p[5];
                        if (rmagic == ~sp->lcp.magic) {
                                int newmagic;
                                if (sp->pp_flags & PP_DEBUG)
                                        printk (KERN_DEBUG "%s: conf nak: magic glitch\n",
                                                dev->name);
                                get_random_bytes(&newmagic, sizeof(newmagic));
                                sp->lcp.magic += newmagic;
                        } else
                                sp->lcp.magic = rmagic;
                        }
                if (sp->lcp.state != LCP_STATE_ACK_SENT) {
                        /* Go to closed state. */
                        sp->lcp.state = LCP_STATE_CLOSED;
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                }
                /* The link will be renegotiated after timeout,
                 * to avoid endless req-nack loop. */
                sppp_clear_timeout (sp);
                sppp_set_timeout (sp, 2);
                break;
        case LCP_CONF_REJ:
                if (h->ident != sp->lcp.confid)
                        break;
                sppp_clear_timeout (sp);
                /* Initiate renegotiation. */
                sppp_lcp_open (sp);
                if (sp->lcp.state != LCP_STATE_ACK_SENT) {
                        /* Go to closed state. */
                        sp->lcp.state = LCP_STATE_CLOSED;
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                }
                break;
        case LCP_TERM_REQ:
                sppp_clear_timeout (sp);
                /* Send Terminate-Ack packet. */
                sppp_cp_send (sp, PPP_LCP, LCP_TERM_ACK, h->ident, 0, NULL);
                /* Go to closed state. */
                sp->lcp.state = LCP_STATE_CLOSED;
                sp->ipcp.state = IPCP_STATE_CLOSED;
                /* Initiate renegotiation. */
                sppp_lcp_open (sp);
                break;
        case LCP_TERM_ACK:
        case LCP_CODE_REJ:
        case LCP_PROTO_REJ:
                /* Ignore for now. */
                break;
        case LCP_DISC_REQ:
                /* Discard the packet. */
                break;
        case LCP_ECHO_REQ:
                if (sp->lcp.state != LCP_STATE_OPENED)
                        break;
                if (len < 8) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: invalid lcp echo request packet length: %d bytes\n",
                                        dev->name, len);
                        break;
                }
                if (ntohl (*(long*)(h+1)) == sp->lcp.magic) {
                        /* Line loopback mode detected. */
                        printk (KERN_WARNING "%s: loopback\n", dev->name);
                        if_down (dev);

                        /* Shut down the PPP link. */
                        sp->lcp.state = LCP_STATE_CLOSED;
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                        sppp_clear_timeout (sp);
                        /* Initiate negotiation. */
                        sppp_lcp_open (sp);
                        break;
                }
                *(long*)(h+1) = htonl (sp->lcp.magic);
                sppp_cp_send (sp, PPP_LCP, LCP_ECHO_REPLY, h->ident, len-4, h+1);
                break;
        case LCP_ECHO_REPLY:
                if (h->ident != sp->lcp.echoid)
                        break;
                if (len < 8) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: invalid lcp echo reply packet length: %d bytes\n",
                                        dev->name, len);
                        break;
                }
                if (ntohl (*(long*)(h+1)) != sp->lcp.magic)
                sp->pp_alivecnt = 0;
                break;
        }
}

/*
 * Handle incoming Cisco keepalive protocol packets.
 */

static void sppp_cisco_input (struct sppp *sp, struct sk_buff *skb)
{
        struct cisco_packet *h;
        struct net_device *dev = sp->pp_if;

        if (!pskb_may_pull(skb, sizeof(struct cisco_packet))
            || (skb->len != CISCO_PACKET_LEN
                && skb->len != CISCO_BIG_PACKET_LEN)) {
                if (sp->pp_flags & PP_DEBUG)
                        printk (KERN_WARNING "%s: invalid cisco packet length: %d bytes\n",
                                dev->name,  skb->len);
                return;
        }
        h = (struct cisco_packet *)skb->data;
        skb_pull(skb, sizeof(struct cisco_packet*));
        if (sp->pp_flags & PP_DEBUG)
                printk (KERN_WARNING "%s: cisco input: %d bytes <%xh %xh %xh %xh %xh-%xh>\n",
                        dev->name,  skb->len,
                        ntohl (h->type), h->par1, h->par2, h->rel,
                        h->time0, h->time1);
        switch (ntohl (h->type)) {
        default:
                if (sp->pp_flags & PP_DEBUG)
                        printk (KERN_WARNING "%s: unknown cisco packet type: 0x%x\n",
                                dev->name,  ntohl (h->type));
                break;
        case CISCO_ADDR_REPLY:
                /* Reply on address request, ignore */
                break;
        case CISCO_KEEPALIVE_REQ:
                sp->pp_alivecnt = 0;
                sp->pp_rseq = ntohl (h->par1);
                if (sp->pp_seq == sp->pp_rseq) {
                        /* Local and remote sequence numbers are equal.
                         * Probably, the line is in loopback mode. */
                        int newseq;
                        if (sp->pp_loopcnt >= MAXALIVECNT) {
                                printk (KERN_WARNING "%s: loopback\n",
                                        dev->name);
                                sp->pp_loopcnt = 0;
                                if (dev->flags & IFF_UP) {
                                        if_down (dev);
                                }
                        }
                        ++sp->pp_loopcnt;

                        /* Generate new local sequence number */
                        get_random_bytes(&newseq, sizeof(newseq));
                        sp->pp_seq ^= newseq;
                        break;
                }
                sp->pp_loopcnt = 0;
                if (sp->pp_link_state==SPPP_LINK_DOWN &&
                    (dev->flags & IFF_UP)) {
                        sp->pp_link_state=SPPP_LINK_UP;
                        printk (KERN_INFO "%s: protocol up\n", dev->name);
                }
                break;
        case CISCO_ADDR_REQ:
                /* Stolen from net/ipv4/devinet.c -- SIOCGIFADDR ioctl */
                {
                struct in_device *in_dev;
                struct in_ifaddr *ifa;
                __be32 addr = 0, mask = ~0; /* FIXME: is the mask correct? */
#ifdef CONFIG_INET
                rcu_read_lock();
                if ((in_dev = __in_dev_get_rcu(dev)) != NULL)
                {
                        for (ifa=in_dev->ifa_list; ifa != NULL;
                                ifa=ifa->ifa_next) {
                                if (strcmp(dev->name, ifa->ifa_label) == 0) 
                                {
                                        addr = ifa->ifa_local;
                                        mask = ifa->ifa_mask;
                                        break;
                                }
                        }
                }
                rcu_read_unlock();
#endif          
                /* I hope both addr and mask are in the net order */
                sppp_cisco_send (sp, CISCO_ADDR_REPLY, addr, mask);
                break;
                }
        }
}


/*
 * Send PPP LCP packet.
 */

static void sppp_cp_send (struct sppp *sp, u16 proto, u8 type,
        u8 ident, u16 len, void *data)
{
        struct ppp_header *h;
        struct lcp_header *lh;
        struct sk_buff *skb;
        struct net_device *dev = sp->pp_if;

        skb=alloc_skb(dev->hard_header_len+PPP_HEADER_LEN+LCP_HEADER_LEN+len,
                GFP_ATOMIC);
        if (skb==NULL)
                return;

        skb_reserve(skb,dev->hard_header_len);
        
        h = (struct ppp_header *)skb_put(skb, sizeof(struct ppp_header));
        h->address = PPP_ALLSTATIONS;        /* broadcast address */
        h->control = PPP_UI;                 /* Unnumbered Info */
        h->protocol = htons (proto);         /* Link Control Protocol */

        lh = (struct lcp_header *)skb_put(skb, sizeof(struct lcp_header));
        lh->type = type;
        lh->ident = ident;
        lh->len = htons (LCP_HEADER_LEN + len);

        if (len)
                memcpy(skb_put(skb,len),data, len);

        if (sp->pp_flags & PP_DEBUG) {
                printk (KERN_WARNING "%s: %s output <%s id=%xh len=%xh",
                        dev->name, 
                        proto==PPP_LCP ? "lcp" : "ipcp",
                        proto==PPP_LCP ? sppp_lcp_type_name (lh->type) :
                        sppp_ipcp_type_name (lh->type), lh->ident,
                        ntohs (lh->len));
                if (len)
                        sppp_print_bytes ((u8*) (lh+1), len);
                printk (">\n");
        }
        sp->obytes += skb->len;
        /* Control is high priority so it doesn't get queued behind data */
        skb->priority=TC_PRIO_CONTROL;
        skb->dev = dev;
        skb_queue_tail(&tx_queue, skb);
}

/*
 * Send Cisco keepalive packet.
 */

static void sppp_cisco_send (struct sppp *sp, int type, long par1, long par2)
{
        struct ppp_header *h;
        struct cisco_packet *ch;
        struct sk_buff *skb;
        struct net_device *dev = sp->pp_if;
        u32 t = jiffies * 1000/HZ;

        skb=alloc_skb(dev->hard_header_len+PPP_HEADER_LEN+CISCO_PACKET_LEN,
                GFP_ATOMIC);

        if(skb==NULL)
                return;
                
        skb_reserve(skb, dev->hard_header_len);
        h = (struct ppp_header *)skb_put (skb, sizeof(struct ppp_header));
        h->address = CISCO_MULTICAST;
        h->control = 0;
        h->protocol = htons (CISCO_KEEPALIVE);

        ch = (struct cisco_packet*)skb_put(skb, CISCO_PACKET_LEN);
        ch->type = htonl (type);
        ch->par1 = htonl (par1);
        ch->par2 = htonl (par2);
        ch->rel = -1;
        ch->time0 = htons ((u16) (t >> 16));
        ch->time1 = htons ((u16) t);

        if (sp->pp_flags & PP_DEBUG)
                printk (KERN_WARNING "%s: cisco output: <%xh %xh %xh %xh %xh-%xh>\n",
                        dev->name,  ntohl (ch->type), ch->par1,
                        ch->par2, ch->rel, ch->time0, ch->time1);
        sp->obytes += skb->len;
        skb->priority=TC_PRIO_CONTROL;
        skb->dev = dev;
        skb_queue_tail(&tx_queue, skb);
}

/**
 *      sppp_close - close down a synchronous PPP or Cisco HDLC link
 *      @dev: The network device to drop the link of
 *
 *      This drops the logical interface to the channel. It is not
 *      done politely as we assume we will also be dropping DTR. Any
 *      timeouts are killed.
 */

int sppp_close (struct net_device *dev)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);
        unsigned long flags;

        spin_lock_irqsave(&sp->lock, flags);
        sp->pp_link_state = SPPP_LINK_DOWN;
        sp->lcp.state = LCP_STATE_CLOSED;
        sp->ipcp.state = IPCP_STATE_CLOSED;
        sppp_clear_timeout (sp);
        spin_unlock_irqrestore(&sp->lock, flags);

        return 0;
}

EXPORT_SYMBOL(sppp_close);

/**
 *      sppp_open - open a synchronous PPP or Cisco HDLC link
 *      @dev:   Network device to activate
 *      
 *      Close down any existing synchronous session and commence
 *      from scratch. In the PPP case this means negotiating LCP/IPCP
 *      and friends, while for Cisco HDLC we simply need to start sending
 *      keepalives
 */

int sppp_open (struct net_device *dev)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);
        unsigned long flags;

        sppp_close(dev);

        spin_lock_irqsave(&sp->lock, flags);
        if (!(sp->pp_flags & PP_CISCO)) {
                sppp_lcp_open (sp);
        }
        sp->pp_link_state = SPPP_LINK_DOWN;
        spin_unlock_irqrestore(&sp->lock, flags);
        sppp_flush_xmit();

        return 0;
}

EXPORT_SYMBOL(sppp_open);

/**
 *      sppp_reopen - notify of physical link loss
 *      @dev: Device that lost the link
 *
 *      This function informs the synchronous protocol code that
 *      the underlying link died (for example a carrier drop on X.21)
 *
 *      We increment the magic numbers to ensure that if the other end
 *      failed to notice we will correctly start a new session. It happens
 *      do to the nature of telco circuits is that you can lose carrier on
 *      one endonly.
 *
 *      Having done this we go back to negotiating. This function may
 *      be called from an interrupt context.
 */
 
int sppp_reopen (struct net_device *dev)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);
        unsigned long flags;

        sppp_close(dev);

        spin_lock_irqsave(&sp->lock, flags);
        if (!(sp->pp_flags & PP_CISCO))
        {
                sp->lcp.magic = jiffies;
                ++sp->pp_seq;
                sp->lcp.state = LCP_STATE_CLOSED;
                sp->ipcp.state = IPCP_STATE_CLOSED;
                /* Give it a moment for the line to settle then go */
                sppp_set_timeout (sp, 1);
        } 
        sp->pp_link_state=SPPP_LINK_DOWN;
        spin_unlock_irqrestore(&sp->lock, flags);

        return 0;
}

EXPORT_SYMBOL(sppp_reopen);

/**
 *      sppp_change_mtu - Change the link MTU
 *      @dev:   Device to change MTU on
 *      @new_mtu: New MTU
 *
 *      Change the MTU on the link. This can only be called with
 *      the link down. It returns an error if the link is up or
 *      the mtu is out of range.
 */
 
static int sppp_change_mtu(struct net_device *dev, int new_mtu)
{
        if(new_mtu<128||new_mtu>PPP_MTU||(dev->flags&IFF_UP))
                return -EINVAL;
        dev->mtu=new_mtu;
        return 0;
}

/**
 *      sppp_do_ioctl - Ioctl handler for ppp/hdlc
 *      @dev: Device subject to ioctl
 *      @ifr: Interface request block from the user
 *      @cmd: Command that is being issued
 *      
 *      This function handles the ioctls that may be issued by the user
 *      to control the settings of a PPP/HDLC link. It does both busy
 *      and security checks. This function is intended to be wrapped by
 *      callers who wish to add additional ioctl calls of their own.
 */
 
int sppp_do_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        struct sppp *sp = (struct sppp *)sppp_of(dev);

        if(dev->flags&IFF_UP)
                return -EBUSY;
                
        if(!capable(CAP_NET_ADMIN))
                return -EPERM;
        
        switch(cmd)
        {
                case SPPPIOCCISCO:
                        sp->pp_flags|=PP_CISCO;
                        dev->type = ARPHRD_HDLC;
                        break;
                case SPPPIOCPPP:
                        sp->pp_flags&=~PP_CISCO;
                        dev->type = ARPHRD_PPP;
                        break;
                case SPPPIOCDEBUG:
                        sp->pp_flags&=~PP_DEBUG;
                        if(ifr->ifr_flags)
                                sp->pp_flags|=PP_DEBUG;
                        break;
                case SPPPIOCGFLAGS:
                        if(copy_to_user(ifr->ifr_data, &sp->pp_flags, sizeof(sp->pp_flags)))
                                return -EFAULT;
                        break;
                case SPPPIOCSFLAGS:
                        if(copy_from_user(&sp->pp_flags, ifr->ifr_data, sizeof(sp->pp_flags)))
                                return -EFAULT;
                        break;
                default:
                        return -EINVAL;
        }
        return 0;
}

EXPORT_SYMBOL(sppp_do_ioctl);

/**
 *      sppp_attach - attach synchronous PPP/HDLC to a device
 *      @pd:    PPP device to initialise
 *
 *      This initialises the PPP/HDLC support on an interface. At the
 *      time of calling the dev element must point to the network device
 *      that this interface is attached to. The interface should not yet
 *      be registered. 
 */
 
void sppp_attach(struct ppp_device *pd)
{
        struct net_device *dev = pd->dev;
        struct sppp *sp = &pd->sppp;
        unsigned long flags;

        /* Make sure embedding is safe for sppp_of */
        BUG_ON(sppp_of(dev) != sp);

        spin_lock_irqsave(&spppq_lock, flags);
        /* Initialize keepalive handler. */
        if (! spppq)
        {
                init_timer(&sppp_keepalive_timer);
                sppp_keepalive_timer.expires=jiffies+10*HZ;
                sppp_keepalive_timer.function=sppp_keepalive;
                add_timer(&sppp_keepalive_timer);
        }
        /* Insert new entry into the keepalive list. */
        sp->pp_next = spppq;
        spppq = sp;
        spin_unlock_irqrestore(&spppq_lock, flags);

        sp->pp_loopcnt = 0;
        sp->pp_alivecnt = 0;
        sp->pp_seq = 0;
        sp->pp_rseq = 0;
        sp->pp_flags = PP_KEEPALIVE|PP_CISCO|debug;/*PP_DEBUG;*/
        sp->lcp.magic = 0;
        sp->lcp.state = LCP_STATE_CLOSED;
        sp->ipcp.state = IPCP_STATE_CLOSED;
        sp->pp_if = dev;
        spin_lock_init(&sp->lock);
        
        /* 
         *      Device specific setup. All but interrupt handler and
         *      hard_start_xmit.
         */
         
        dev->hard_header = sppp_hard_header;
        dev->rebuild_header = sppp_rebuild_header;
        dev->tx_queue_len = 10;
        dev->type = ARPHRD_HDLC;
        dev->addr_len = 0;
        dev->hard_header_len = sizeof(struct ppp_header);
        dev->mtu = PPP_MTU;
        /*
         *      These 4 are callers but MUST also call sppp_ functions
         */
        dev->do_ioctl = sppp_do_ioctl;
#if 0
        dev->get_stats = NULL;          /* Let the driver override these */
        dev->open = sppp_open;
        dev->stop = sppp_close;
#endif  
        dev->change_mtu = sppp_change_mtu;
        dev->hard_header_cache = NULL;
        dev->header_cache_update = NULL;
        dev->flags = IFF_MULTICAST|IFF_POINTOPOINT|IFF_NOARP;
}

EXPORT_SYMBOL(sppp_attach);

/**
 *      sppp_detach - release PPP resources from a device
 *      @dev:   Network device to release
 *
 *      Stop and free up any PPP/HDLC resources used by this
 *      interface. This must be called before the device is
 *      freed.
 */
 
void sppp_detach (struct net_device *dev)
{
        struct sppp **q, *p, *sp = (struct sppp *)sppp_of(dev);
        unsigned long flags;

        spin_lock_irqsave(&spppq_lock, flags);
        /* Remove the entry from the keepalive list. */
        for (q = &spppq; (p = *q); q = &p->pp_next)
                if (p == sp) {
                        *q = p->pp_next;
                        break;
                }

        /* Stop keepalive handler. */
        if (! spppq)
                del_timer(&sppp_keepalive_timer);
        sppp_clear_timeout (sp);
        spin_unlock_irqrestore(&spppq_lock, flags);
}

EXPORT_SYMBOL(sppp_detach);

/*
 * Analyze the LCP Configure-Request options list
 * for the presence of unknown options.
 * If the request contains unknown options, build and
 * send Configure-reject packet, containing only unknown options.
 */
static int
sppp_lcp_conf_parse_options (struct sppp *sp, struct lcp_header *h,
        int len, u32 *magic)
{
        u8 *buf, *r, *p;
        int rlen;

        len -= 4;
        buf = r = kmalloc (len, GFP_ATOMIC);
        if (! buf)
                return (0);

        p = (void*) (h+1);
        for (rlen=0; len>1 && p[1]; len-=p[1], p+=p[1]) {
                switch (*p) {
                case LCP_OPT_MAGIC:
                        /* Magic number -- extract. */
                        if (len >= 6 && p[1] == 6) {
                                *magic = (u32)p[2] << 24 |
                                        (u32)p[3] << 16 | p[4] << 8 | p[5];
                                continue;
                        }
                        break;
                case LCP_OPT_ASYNC_MAP:
                        /* Async control character map -- check to be zero. */
                        if (len >= 6 && p[1] == 6 && ! p[2] && ! p[3] &&
                            ! p[4] && ! p[5])
                                continue;
                        break;
                case LCP_OPT_MRU:
                        /* Maximum receive unit -- always OK. */
                        continue;
                default:
                        /* Others not supported. */
                        break;
                }
                /* Add the option to rejected list. */
                memcpy(r, p, p[1]);
                r += p[1];
                rlen += p[1];
        }
        if (rlen)
                sppp_cp_send (sp, PPP_LCP, LCP_CONF_REJ, h->ident, rlen, buf);
        kfree(buf);
        return (rlen == 0);
}

static void sppp_ipcp_input (struct sppp *sp, struct sk_buff *skb)
{
        struct lcp_header *h;
        struct net_device *dev = sp->pp_if;
        int len = skb->len;

        if (!pskb_may_pull(skb, sizeof(struct lcp_header))) {
                if (sp->pp_flags & PP_DEBUG)
                        printk (KERN_WARNING "%s: invalid ipcp packet length: %d bytes\n",
                                dev->name,  len);
                return;
        }
        h = (struct lcp_header *)skb->data;
        skb_pull(skb,sizeof(struct lcp_header));
        if (sp->pp_flags & PP_DEBUG) {
                printk (KERN_WARNING "%s: ipcp input: %d bytes <%s id=%xh len=%xh",
                        dev->name,  len,
                        sppp_ipcp_type_name (h->type), h->ident, ntohs (h->len));
                if (len > 4)
                        sppp_print_bytes ((u8*) (h+1), len-4);
                printk (">\n");
        }
        if (len > ntohs (h->len))
                len = ntohs (h->len);
        switch (h->type) {
        default:
                /* Unknown packet type -- send Code-Reject packet. */
                sppp_cp_send (sp, PPP_IPCP, IPCP_CODE_REJ, ++sp->pp_seq, len, h);
                break;
        case IPCP_CONF_REQ:
                if (len < 4) {
                        if (sp->pp_flags & PP_DEBUG)
                                printk (KERN_WARNING "%s: invalid ipcp configure request packet length: %d bytes\n",
                                        dev->name, len);
                        return;
                }
                if (len > 4) {
                        sppp_cp_send (sp, PPP_IPCP, LCP_CONF_REJ, h->ident,
                                len-4, h+1);

                        switch (sp->ipcp.state) {
                        case IPCP_STATE_OPENED:
                                /* Initiate renegotiation. */
                                sppp_ipcp_open (sp);
                                /* fall through... */
                        case IPCP_STATE_ACK_SENT:
                                /* Go to closed state. */
                                sp->ipcp.state = IPCP_STATE_CLOSED;
                        }
                } else {
                        /* Send Configure-Ack packet. */
                        sppp_cp_send (sp, PPP_IPCP, IPCP_CONF_ACK, h->ident,
                                0, NULL);
                        /* Change the state. */
                        if (sp->ipcp.state == IPCP_STATE_ACK_RCVD)
                                sp->ipcp.state = IPCP_STATE_OPENED;
                        else
                                sp->ipcp.state = IPCP_STATE_ACK_SENT;
                }
                break;
        case IPCP_CONF_ACK:
                if (h->ident != sp->ipcp.confid)
                        break;
                sppp_clear_timeout (sp);
                switch (sp->ipcp.state) {
                case IPCP_STATE_CLOSED:
                        sp->ipcp.state = IPCP_STATE_ACK_RCVD;
                        sppp_set_timeout (sp, 5);
                        break;
                case IPCP_STATE_ACK_SENT:
                        sp->ipcp.state = IPCP_STATE_OPENED;
                        break;
                }
                break;
        case IPCP_CONF_NAK:
        case IPCP_CONF_REJ:
                if (h->ident != sp->ipcp.confid)
                        break;
                sppp_clear_timeout (sp);
                        /* Initiate renegotiation. */
                sppp_ipcp_open (sp);
                if (sp->ipcp.state != IPCP_STATE_ACK_SENT)
                        /* Go to closed state. */
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                break;
        case IPCP_TERM_REQ:
                /* Send Terminate-Ack packet. */
                sppp_cp_send (sp, PPP_IPCP, IPCP_TERM_ACK, h->ident, 0, NULL);
                /* Go to closed state. */
                sp->ipcp.state = IPCP_STATE_CLOSED;
                /* Initiate renegotiation. */
                sppp_ipcp_open (sp);
                break;
        case IPCP_TERM_ACK:
                /* Ignore for now. */
        case IPCP_CODE_REJ:
                /* Ignore for now. */
                break;
        }
}

static void sppp_lcp_open (struct sppp *sp)
{
        char opt[6];

        if (! sp->lcp.magic)
                sp->lcp.magic = jiffies;
        opt[0] = LCP_OPT_MAGIC;
        opt[1] = sizeof (opt);
        opt[2] = sp->lcp.magic >> 24;
        opt[3] = sp->lcp.magic >> 16;
        opt[4] = sp->lcp.magic >> 8;
        opt[5] = sp->lcp.magic;
        sp->lcp.confid = ++sp->pp_seq;
        sppp_cp_send (sp, PPP_LCP, LCP_CONF_REQ, sp->lcp.confid,
                sizeof (opt), &opt);
        sppp_set_timeout (sp, 2);
}

static void sppp_ipcp_open (struct sppp *sp)
{
        sp->ipcp.confid = ++sp->pp_seq;
        sppp_cp_send (sp, PPP_IPCP, IPCP_CONF_REQ, sp->ipcp.confid, 0, NULL);
        sppp_set_timeout (sp, 2);
}

/*
 * Process PPP control protocol timeouts.
 */
 
static void sppp_cp_timeout (unsigned long arg)
{
        struct sppp *sp = (struct sppp*) arg;
        unsigned long flags;

        spin_lock_irqsave(&sp->lock, flags);

        sp->pp_flags &= ~PP_TIMO;
        if (! (sp->pp_if->flags & IFF_UP) || (sp->pp_flags & PP_CISCO)) {
                spin_unlock_irqrestore(&sp->lock, flags);
                return;
        }
        switch (sp->lcp.state) {
        case LCP_STATE_CLOSED:
                /* No ACK for Configure-Request, retry. */
                sppp_lcp_open (sp);
                break;
        case LCP_STATE_ACK_RCVD:
                /* ACK got, but no Configure-Request for peer, retry. */
                sppp_lcp_open (sp);
                sp->lcp.state = LCP_STATE_CLOSED;
                break;
        case LCP_STATE_ACK_SENT:
                /* ACK sent but no ACK for Configure-Request, retry. */
                sppp_lcp_open (sp);
                break;
        case LCP_STATE_OPENED:
                /* LCP is already OK, try IPCP. */
                switch (sp->ipcp.state) {
                case IPCP_STATE_CLOSED:
                        /* No ACK for Configure-Request, retry. */
                        sppp_ipcp_open (sp);
                        break;
                case IPCP_STATE_ACK_RCVD:
                        /* ACK got, but no Configure-Request for peer, retry. */
                        sppp_ipcp_open (sp);
                        sp->ipcp.state = IPCP_STATE_CLOSED;
                        break;
                case IPCP_STATE_ACK_SENT:
                        /* ACK sent but no ACK for Configure-Request, retry. */
                        sppp_ipcp_open (sp);
                        break;
                case IPCP_STATE_OPENED:
                        /* IPCP is OK. */
                        break;
                }
                break;
        }
        spin_unlock_irqrestore(&sp->lock, flags);
        sppp_flush_xmit();
}

static char *sppp_lcp_type_name (u8 type)
{
        static char buf [8];
        switch (type) {
        case LCP_CONF_REQ:   return ("conf-req");
        case LCP_CONF_ACK:   return ("conf-ack");
        case LCP_CONF_NAK:   return ("conf-nack");
        case LCP_CONF_REJ:   return ("conf-rej");
        case LCP_TERM_REQ:   return ("term-req");
        case LCP_TERM_ACK:   return ("term-ack");
        case LCP_CODE_REJ:   return ("code-rej");
        case LCP_PROTO_REJ:  return ("proto-rej");
        case LCP_ECHO_REQ:   return ("echo-req");
        case LCP_ECHO_REPLY: return ("echo-reply");
        case LCP_DISC_REQ:   return ("discard-req");
        }
        sprintf (buf, "%xh", type);
        return (buf);
}

static char *sppp_ipcp_type_name (u8 type)
{
        static char buf [8];
        switch (type) {
        case IPCP_CONF_REQ:   return ("conf-req");
        case IPCP_CONF_ACK:   return ("conf-ack");
        case IPCP_CONF_NAK:   return ("conf-nack");
        case IPCP_CONF_REJ:   return ("conf-rej");
        case IPCP_TERM_REQ:   return ("term-req");
        case IPCP_TERM_ACK:   return ("term-ack");
        case IPCP_CODE_REJ:   return ("code-rej");
        }
        sprintf (buf, "%xh", type);
        return (buf);
}

static void sppp_print_bytes (u_char *p, u16 len)
{
        printk (" %x", *p++);
        while (--len > 0)
                printk ("-%x", *p++);
}

/**
 *      sppp_rcv -      receive and process a WAN PPP frame
 *      @skb:   The buffer to process
 *      @dev:   The device it arrived on
 *      @p: Unused
 *      @orig_dev: Unused
 *
 *      Protocol glue. This drives the deferred processing mode the poorer
 *      cards use. This can be called directly by cards that do not have
 *      timing constraints but is normally called from the network layer
 *      after interrupt servicing to process frames queued via netif_rx.
 */

static int sppp_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *p, struct net_device *orig_dev)
{
        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                return NET_RX_DROP;
        sppp_input(dev,skb);
        return 0;
}

static struct packet_type sppp_packet_type = {
        .type   = __constant_htons(ETH_P_WAN_PPP),
        .func   = sppp_rcv,
};

static char banner[] __initdata = 
        KERN_INFO "Cronyx Ltd, Synchronous PPP and CISCO HDLC (c) 1994\n"
        KERN_INFO "Linux port (c) 1998 Building Number Three Ltd & "
                  "Jan \"Yenya\" Kasprzak.\n";

static int __init sync_ppp_init(void)
{
        if(debug)
                debug=PP_DEBUG;
        printk(banner);
        skb_queue_head_init(&tx_queue);
        dev_add_pack(&sppp_packet_type);
        return 0;
}


static void __exit sync_ppp_cleanup(void)
{
        dev_remove_pack(&sppp_packet_type);
}

module_init(sync_ppp_init);
module_exit(sync_ppp_cleanup);
module_param(debug, int, 0);
MODULE_LICENSE("GPL");