text: /*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		Definitions for the IP module.
   *
   * Version:	@(#)ip.h	1.0.2	05/07/93
   *
   * Authors:	Ross Biro
   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *		Alan Cox, <gw4pts@gw4pts.ampr.org>
   *
   * Changes:
   *		Mike McLagan    :       Routing by 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.
   */
  #ifndef _IP_H
  #define _IP_H
  
  #include <linux/types.h>
  #include <linux/ip.h>
  #include <linux/in.h>
  #include <linux/skbuff.h>
  
  #include <net/inet_sock.h>
  #include <net/snmp.h>
  #include <net/flow.h>
  
  struct sock;
  
  struct inet_skb_parm {
  	struct ip_options	opt;		/* Compiled IP options		*/
  	unsigned char		flags;
  
  #define IPSKB_FORWARDED		1
  #define IPSKB_XFRM_TUNNEL_SIZE	2
  #define IPSKB_XFRM_TRANSFORMED	4
  #define IPSKB_FRAG_COMPLETE	8
  #define IPSKB_REROUTED		16
  };
  
  static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
  {
  	return ip_hdr(skb)->ihl * 4;
  }
  
  struct ipcm_cookie {
  	__be32			addr;
  	int			oif;
  	struct ip_options_rcu	*opt;
  	__u8			tx_flags;
  };
  
  #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
  
  struct ip_ra_chain {
  	struct ip_ra_chain __rcu *next;
  	struct sock		*sk;
  	union {
  		void			(*destructor)(struct sock *);
  		struct sock		*saved_sk;
  	};
  	struct rcu_head		rcu;
  };
  
  extern struct ip_ra_chain __rcu *ip_ra_chain;
  
  /* IP flags. */
  #define IP_CE		0x8000		/* Flag: "Congestion"		*/
  #define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
  #define IP_MF		0x2000		/* Flag: "More Fragments"	*/
  #define IP_OFFSET	0x1FFF		/* "Fragment Offset" part	*/
  
  #define IP_FRAG_TIME	(30 * HZ)		/* fragment lifetime	*/
  
  struct msghdr;
  struct net_device;
  struct packet_type;
  struct rtable;
  struct sockaddr;
  
  extern int		igmp_mc_proc_init(void);
  
  /*
   *	Functions provided by ip.c
   */
  
  extern int		ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
  					      __be32 saddr, __be32 daddr,
  					      struct ip_options_rcu *opt);
  extern int		ip_rcv(struct sk_buff *skb, struct net_device *dev,
  			       struct packet_type *pt, struct net_device *orig_dev);
  extern int		ip_local_deliver(struct sk_buff *skb);
  extern int		ip_mr_input(struct sk_buff *skb);
  extern int		ip_output(struct sk_buff *skb);
  extern int		ip_mc_output(struct sk_buff *skb);
  extern int		ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
  extern int		ip_do_nat(struct sk_buff *skb);
  extern void		ip_send_check(struct iphdr *ip);
  extern int		__ip_local_out(struct sk_buff *skb);
  extern int		ip_local_out(struct sk_buff *skb);
  extern int		ip_queue_xmit(struct sk_buff *skb, struct flowi *fl);
  extern void		ip_init(void);
  extern int		ip_append_data(struct sock *sk, struct flowi4 *fl4,
  				       int getfrag(void *from, char *to, int offset, int len,
  						   int odd, struct sk_buff *skb),
  				void *from, int len, int protolen,
  				struct ipcm_cookie *ipc,
  				struct rtable **rt,
  				unsigned int flags);
  extern int		ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb);
  extern ssize_t		ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
  				int offset, size_t size, int flags);
  extern struct sk_buff  *__ip_make_skb(struct sock *sk,
  				      struct flowi4 *fl4,
  				      struct sk_buff_head *queue,
  				      struct inet_cork *cork);
  extern int		ip_send_skb(struct sk_buff *skb);
  extern int		ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4);
  extern void		ip_flush_pending_frames(struct sock *sk);
  extern struct sk_buff  *ip_make_skb(struct sock *sk,
  				    struct flowi4 *fl4,
  				    int getfrag(void *from, char *to, int offset, int len,
  						int odd, struct sk_buff *skb),
  				    void *from, int length, int transhdrlen,
  				    struct ipcm_cookie *ipc,
  				    struct rtable **rtp,
  				    unsigned int flags);
  
  static inline struct sk_buff *ip_finish_skb(struct sock *sk, struct flowi4 *fl4)
  {
  	return __ip_make_skb(sk, fl4, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
  }
  
  /* datagram.c */
  extern int		ip4_datagram_connect(struct sock *sk, 
  					     struct sockaddr *uaddr, int addr_len);
  
  /*
   *	Map a multicast IP onto multicast MAC for type Token Ring.
   *      This conforms to RFC1469 Option 2 Multicasting i.e.
   *      using a functional address to transmit / receive 
   *      multicast packets.
   */
  
  static inline void ip_tr_mc_map(__be32 addr, char *buf)
  {
  	buf[0]=0xC0;
  	buf[1]=0x00;
  	buf[2]=0x00;
  	buf[3]=0x04;
  	buf[4]=0x00;
  	buf[5]=0x00;
  }
  
  struct ip_reply_arg {
  	struct kvec iov[1];   
  	int	    flags;
  	__wsum 	    csum;
  	int	    csumoffset; /* u16 offset of csum in iov[0].iov_base */
  				/* -1 if not needed */ 
  	int	    bound_dev_if;
  }; 
  
  #define IP_REPLY_ARG_NOSRCCHECK 1
  
  static inline __u8 ip_reply_arg_flowi_flags(const struct ip_reply_arg *arg)
  {
  	return (arg->flags & IP_REPLY_ARG_NOSRCCHECK) ? FLOWI_FLAG_ANYSRC : 0;
  }
  
  void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
  		   struct ip_reply_arg *arg, unsigned int len);
  
  struct ipv4_config {
  	int	log_martians;
  	int	no_pmtu_disc;
  };
  
  extern struct ipv4_config ipv4_config;
  #define IP_INC_STATS(net, field)	SNMP_INC_STATS64((net)->mib.ip_statistics, field)
  #define IP_INC_STATS_BH(net, field)	SNMP_INC_STATS64_BH((net)->mib.ip_statistics, field)
  #define IP_ADD_STATS(net, field, val)	SNMP_ADD_STATS64((net)->mib.ip_statistics, field, val)
  #define IP_ADD_STATS_BH(net, field, val) SNMP_ADD_STATS64_BH((net)->mib.ip_statistics, field, val)
  #define IP_UPD_PO_STATS(net, field, val) SNMP_UPD_PO_STATS64((net)->mib.ip_statistics, field, val)
  #define IP_UPD_PO_STATS_BH(net, field, val) SNMP_UPD_PO_STATS64_BH((net)->mib.ip_statistics, field, val)
  #define NET_INC_STATS(net, field)	SNMP_INC_STATS((net)->mib.net_statistics, field)
  #define NET_INC_STATS_BH(net, field)	SNMP_INC_STATS_BH((net)->mib.net_statistics, field)
  #define NET_INC_STATS_USER(net, field) 	SNMP_INC_STATS_USER((net)->mib.net_statistics, field)
  #define NET_ADD_STATS_BH(net, field, adnd) SNMP_ADD_STATS_BH((net)->mib.net_statistics, field, adnd)
  #define NET_ADD_STATS_USER(net, field, adnd) SNMP_ADD_STATS_USER((net)->mib.net_statistics, field, adnd)
  
  extern unsigned long snmp_fold_field(void __percpu *mib[], int offt);
  #if BITS_PER_LONG==32
  extern u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t sync_off);
  #else
  static inline u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_off)
  {
  	return snmp_fold_field(mib, offt);
  }
  #endif
  extern int snmp_mib_init(void __percpu *ptr[2], size_t mibsize, size_t align);
  extern void snmp_mib_free(void __percpu *ptr[2]);
  
  extern struct local_ports {
  	seqlock_t	lock;
  	int		range[2];
  } sysctl_local_ports;
  extern void inet_get_local_port_range(int *low, int *high);
  
  extern unsigned long *sysctl_local_reserved_ports;
  static inline int inet_is_reserved_local_port(int port)
  {
  	return test_bit(port, sysctl_local_reserved_ports);
  }
  
  extern int sysctl_ip_nonlocal_bind;
  
  extern struct ctl_path net_core_path[];
  extern struct ctl_path net_ipv4_ctl_path[];
  
  /* From inetpeer.c */
  extern int inet_peer_threshold;
  extern int inet_peer_minttl;
  extern int inet_peer_maxttl;
  extern int inet_peer_gc_mintime;
  extern int inet_peer_gc_maxtime;
  
  /* From ip_output.c */
  extern int sysctl_ip_dynaddr;
  
  extern void ipfrag_init(void);
  
  extern void ip_static_sysctl_init(void);
  
  #ifdef CONFIG_INET
  #include <net/dst.h>
  
  /* The function in 2.2 was invalid, producing wrong result for
   * check=0xFEFF. It was noticed by Arthur Skawina _year_ ago. --ANK(000625) */
  static inline
  int ip_decrease_ttl(struct iphdr *iph)
  {
  	u32 check = (__force u32)iph->check;
  	check += (__force u32)htons(0x0100);
  	iph->check = (__force __sum16)(check + (check>=0xFFFF));
  	return --iph->ttl;
  }
  
  static inline
  int ip_dont_fragment(struct sock *sk, struct dst_entry *dst)
  {
  	return  inet_sk(sk)->pmtudisc == IP_PMTUDISC_DO ||
  		(inet_sk(sk)->pmtudisc == IP_PMTUDISC_WANT &&
  		 !(dst_metric_locked(dst, RTAX_MTU)));
  }
  
  extern void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more);
  
  static inline void ip_select_ident(struct iphdr *iph, struct dst_entry *dst, struct sock *sk)
  {
  	if (iph->frag_off & htons(IP_DF)) {
  		/* This is only to work around buggy Windows95/2000
  		 * VJ compression implementations.  If the ID field
  		 * does not change, they drop every other packet in
  		 * a TCP stream using header compression.
  		 */
  		iph->id = (sk && inet_sk(sk)->inet_daddr) ?
  					htons(inet_sk(sk)->inet_id++) : 0;
  	} else
  		__ip_select_ident(iph, dst, 0);
  }
  
  static inline void ip_select_ident_more(struct iphdr *iph, struct dst_entry *dst, struct sock *sk, int more)
  {
  	if (iph->frag_off & htons(IP_DF)) {
  		if (sk && inet_sk(sk)->inet_daddr) {
  			iph->id = htons(inet_sk(sk)->inet_id);
  			inet_sk(sk)->inet_id += 1 + more;
  		} else
  			iph->id = 0;
  	} else
  		__ip_select_ident(iph, dst, more);
  }
  
  /*
   *	Map a multicast IP onto multicast MAC for type ethernet.
   */
  
  static inline void ip_eth_mc_map(__be32 naddr, char *buf)
  {
  	__u32 addr=ntohl(naddr);
  	buf[0]=0x01;
  	buf[1]=0x00;
  	buf[2]=0x5e;
  	buf[5]=addr&0xFF;
  	addr>>=8;
  	buf[4]=addr&0xFF;
  	addr>>=8;
  	buf[3]=addr&0x7F;
  }
  
  /*
   *	Map a multicast IP onto multicast MAC for type IP-over-InfiniBand.
   *	Leave P_Key as 0 to be filled in by driver.
   */
  
  static inline void ip_ib_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
  {
  	__u32 addr;
  	unsigned char scope = broadcast[5] & 0xF;
  
  	buf[0]  = 0;		/* Reserved */
  	buf[1]  = 0xff;		/* Multicast QPN */
  	buf[2]  = 0xff;
  	buf[3]  = 0xff;
  	addr    = ntohl(naddr);
  	buf[4]  = 0xff;
  	buf[5]  = 0x10 | scope;	/* scope from broadcast address */
  	buf[6]  = 0x40;		/* IPv4 signature */
  	buf[7]  = 0x1b;
  	buf[8]  = broadcast[8];		/* P_Key */
  	buf[9]  = broadcast[9];
  	buf[10] = 0;
  	buf[11] = 0;
  	buf[12] = 0;
  	buf[13] = 0;
  	buf[14] = 0;
  	buf[15] = 0;
  	buf[19] = addr & 0xff;
  	addr  >>= 8;
  	buf[18] = addr & 0xff;
  	addr  >>= 8;
  	buf[17] = addr & 0xff;
  	addr  >>= 8;
  	buf[16] = addr & 0x0f;
  }
  
  static inline void ip_ipgre_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
  {
  	if ((broadcast[0] | broadcast[1] | broadcast[2] | broadcast[3]) != 0)
  		memcpy(buf, broadcast, 4);
  	else
  		memcpy(buf, &naddr, sizeof(naddr));
  }
  
  #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  #include <linux/ipv6.h>
  #endif
  
  static __inline__ void inet_reset_saddr(struct sock *sk)
  {
  	inet_sk(sk)->inet_rcv_saddr = inet_sk(sk)->inet_saddr = 0;
  #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  	if (sk->sk_family == PF_INET6) {
  		struct ipv6_pinfo *np = inet6_sk(sk);
  
  		memset(&np->saddr, 0, sizeof(np->saddr));
  		memset(&np->rcv_saddr, 0, sizeof(np->rcv_saddr));
  	}
  #endif
  }
  
  #endif
  
  static inline int sk_mc_loop(struct sock *sk)
  {
  	if (!sk)
  		return 1;
  	switch (sk->sk_family) {
  	case AF_INET:
  		return inet_sk(sk)->mc_loop;
  #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  	case AF_INET6:
  		return inet6_sk(sk)->mc_loop;
  #endif
  	}
  	WARN_ON(1);
  	return 1;
  }
  
  extern int	ip_call_ra_chain(struct sk_buff *skb);
  
  /*
   *	Functions provided by ip_fragment.c
   */
  
  enum ip_defrag_users {
  	IP_DEFRAG_LOCAL_DELIVER,
  	IP_DEFRAG_CALL_RA_CHAIN,
  	IP_DEFRAG_CONNTRACK_IN,
  	__IP_DEFRAG_CONNTRACK_IN_END	= IP_DEFRAG_CONNTRACK_IN + USHRT_MAX,
  	IP_DEFRAG_CONNTRACK_OUT,
  	__IP_DEFRAG_CONNTRACK_OUT_END	= IP_DEFRAG_CONNTRACK_OUT + USHRT_MAX,
  	IP_DEFRAG_CONNTRACK_BRIDGE_IN,
  	__IP_DEFRAG_CONNTRACK_BRIDGE_IN = IP_DEFRAG_CONNTRACK_BRIDGE_IN + USHRT_MAX,
  	IP_DEFRAG_VS_IN,
  	IP_DEFRAG_VS_OUT,
  	IP_DEFRAG_VS_FWD
  };
  
  int ip_defrag(struct sk_buff *skb, u32 user);
  int ip_frag_mem(struct net *net);
  int ip_frag_nqueues(struct net *net);
  
  /*
   *	Functions provided by ip_forward.c
   */
   
  extern int ip_forward(struct sk_buff *skb);
   
  /*
   *	Functions provided by ip_options.c
   */
   
  extern void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
  			     __be32 daddr, struct rtable *rt, int is_frag);
  extern int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb);
  extern void ip_options_fragment(struct sk_buff *skb);
  extern int ip_options_compile(struct net *net,
  			      struct ip_options *opt, struct sk_buff *skb);
  extern int ip_options_get(struct net *net, struct ip_options_rcu **optp,
  			  unsigned char *data, int optlen);
  extern int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
  				    unsigned char __user *data, int optlen);
  extern void ip_options_undo(struct ip_options * opt);
  extern void ip_forward_options(struct sk_buff *skb);
  extern int ip_options_rcv_srr(struct sk_buff *skb);
  
  /*
   *	Functions provided by ip_sockglue.c
   */
  
  extern int	ip_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
  extern void	ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
  extern int	ip_cmsg_send(struct net *net,
  			     struct msghdr *msg, struct ipcm_cookie *ipc);
  extern int	ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval, unsigned int optlen);
  extern int	ip_getsockopt(struct sock *sk, int level, int optname, char __user *optval, int __user *optlen);
  extern int	compat_ip_setsockopt(struct sock *sk, int level,
  			int optname, char __user *optval, unsigned int optlen);
  extern int	compat_ip_getsockopt(struct sock *sk, int level,
  			int optname, char __user *optval, int __user *optlen);
  extern int	ip_ra_control(struct sock *sk, unsigned char on, void (*destructor)(struct sock *));
  
  extern int 	ip_recv_error(struct sock *sk, struct msghdr *msg, int len);
  extern void	ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err, 
  			      __be16 port, u32 info, u8 *payload);
  extern void	ip_local_error(struct sock *sk, int err, __be32 daddr, __be16 dport,
  			       u32 info);
  
  #ifdef CONFIG_PROC_FS
  extern int ip_misc_proc_init(void);
  #endif
  
  #endif	/* _IP_H */
  