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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/net_namespace.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;
      __be16 protocol;
};
#define PPP_HEADER_LEN          sizeof (struct ppp_header)

struct lcp_header {
      u8 type;
      u8 ident;
      __be16 len;
};
#define LCP_HEADER_LEN          sizeof (struct lcp_header)

struct cisco_packet {
      __be32 type;
      __be32 par1;
      __be32 par2;
      __be16 rel;
      __be16 time0;
      __be16 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, u32 par1, u32 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_reset_mac_header(skb);

      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,
                      const void *daddr, const 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 const struct header_ops sppp_header_ops = {
      .create = sppp_hard_header,
};

/*
 * 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) {
                  __be32 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 (*(__be32*)(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;
            }
            *(__be32 *)(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(*(__be32 *)(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 = htonl(~0U); /* 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            
            sppp_cisco_send (sp, CISCO_ADDR_REPLY, ntohl(addr), ntohl(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, u32 par1, u32 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 = htons(0xffff);
      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->header_ops = &sppp_header_ops;

      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->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 (dev->nd_net != &init_net) {
            kfree_skb(skb);
            return 0;
      }

      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");


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