text: /***************************************************************************
   * Linux PPP over X - Generic PPP transport layer sockets
   * Linux PPP over Ethernet (PPPoE) Socket Implementation (RFC 2516) 
   *
   * This file supplies definitions required by the PPP over Ethernet driver
   * (pppox.c).  All version information wrt this file is located in pppox.c
   *
   * License:
   *		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.
   *
   */
  #ifndef __LINUX_IF_PPPOX_H
  #define __LINUX_IF_PPPOX_H
  
  #include <linux/if.h>
  #include <linux/netdevice.h>
  #include <linux/ppp_channel.h>
  #include <linux/skbuff.h>
  #include <linux/workqueue.h>
  #include <uapi/linux/if_pppox.h>
  
  static inline struct pppoe_hdr *pppoe_hdr(const struct sk_buff *skb)
  {
  	return (struct pppoe_hdr *)skb_network_header(skb);
  }
  
  struct pppoe_opt {
  	struct net_device      *dev;	  /* device associated with socket*/
  	int			ifindex;  /* ifindex of device associated with socket */
  	struct pppoe_addr	pa;	  /* what this socket is bound to*/
  	struct sockaddr_pppox	relay;	  /* what socket data will be
  					     relayed to (PPPoE relaying) */
  	struct work_struct      padt_work;/* Work item for handling PADT */
  };
  
  struct pptp_opt {
  	struct pptp_addr src_addr;
  	struct pptp_addr dst_addr;
  	u32 ack_sent, ack_recv;
  	u32 seq_sent, seq_recv;
  	int ppp_flags;
  };
  #include <net/sock.h>
  
  struct pppox_sock {
  	/* struct sock must be the first member of pppox_sock */
  	struct sock sk;
  	struct ppp_channel chan;
  	struct pppox_sock	*next;	  /* for hash table */
  	union {
  		struct pppoe_opt pppoe;
  		struct pptp_opt  pptp;
  	} proto;
  	__be16			num;
  };
  #define pppoe_dev	proto.pppoe.dev
  #define pppoe_ifindex	proto.pppoe.ifindex
  #define pppoe_pa	proto.pppoe.pa
  #define pppoe_relay	proto.pppoe.relay
  
  static inline struct pppox_sock *pppox_sk(struct sock *sk)
  {
  	return (struct pppox_sock *)sk;
  }
  
  static inline struct sock *sk_pppox(struct pppox_sock *po)
  {
  	return (struct sock *)po;
  }
  
  struct module;
  
  struct pppox_proto {
  	int		(*create)(struct net *net, struct socket *sock);
  	int		(*ioctl)(struct socket *sock, unsigned int cmd,
  				 unsigned long arg);
  	struct module	*owner;
  };
  
  extern int register_pppox_proto(int proto_num, const struct pppox_proto *pp);
  extern void unregister_pppox_proto(int proto_num);
  extern void pppox_unbind_sock(struct sock *sk);/* delete ppp-channel binding */
  extern int pppox_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
  
  /* PPPoX socket states */
  enum {
      PPPOX_NONE		= 0,  /* initial state */
      PPPOX_CONNECTED	= 1,  /* connection established ==TCP_ESTABLISHED */
      PPPOX_BOUND		= 2,  /* bound to ppp device */
      PPPOX_RELAY		= 4,  /* forwarding is enabled */
      PPPOX_ZOMBIE	= 8,  /* dead, but still bound to ppp device */
      PPPOX_DEAD		= 16  /* dead, useless, please clean me up!*/
  };
  
  #endif /* !(__LINUX_IF_PPPOX_H) */
  