include/net/ip.h

/*
 * 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>

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	*opt;
};

#define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))

struct ip_ra_chain
{
	struct ip_ra_chain	*next;
	struct sock		*sk;
	void			(*destructor)(struct sock *);
};

extern struct ip_ra_chain *ip_ra_chain;
extern rwlock_t ip_ra_lock;

/* 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 *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, int ipfragok);
extern void		ip_init(void);
extern int		ip_append_data(struct sock *sk,
				       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 page *page,
				int offset, size_t size, int flags);
extern int		ip_push_pending_frames(struct sock *sk);
extern void		ip_flush_pending_frames(struct sock *sk);

/* 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];   
	__wsum 	    csum;
	int	    csumoffset; /* u16 offset of csum in iov[0].iov_base */
				/* -1 if not needed */ 
	int	    bound_dev_if;
}; 

void ip_send_reply(struct sock *sk, struct sk_buff *skb, 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_STATS((net)->mib.ip_statistics, field)
#define IP_INC_STATS_BH(net, field)	SNMP_INC_STATS_BH((net)->mib.ip_statistics, field)
#define IP_ADD_STATS_BH(net, field, val) SNMP_ADD_STATS_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 *mib[], int offt);
extern int snmp_mib_init(void *ptr[2], size_t mibsize);
extern void snmp_mib_free(void *ptr[2]);

extern void inet_get_local_port_range(int *low, int *high);

extern int sysctl_ip_default_ttl;
extern int sysctl_ip_nonlocal_bind;

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)->daddr) ?
					htons(inet_sk(sk)->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)->daddr) {
			iph->id = htons(inet_sk(sk)->id);
			inet_sk(sk)->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;
}

#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)->rcv_saddr = inet_sk(sk)->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

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_OUT,
	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 **optp,
			  unsigned char *data, int optlen);
extern int ip_options_get_from_user(struct net *net, struct ip_options **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 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, 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, 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);

/* sysctl helpers - any sysctl which holds a value that ends up being
 * fed into the routing cache should use these handlers.
 */
int ipv4_doint_and_flush(ctl_table *ctl, int write,
			 struct file* filp, void __user *buffer,
			 size_t *lenp, loff_t *ppos);
int ipv4_doint_and_flush_strategy(ctl_table *table, int __user *name, int nlen,
				  void __user *oldval, size_t __user *oldlenp,
				  void __user *newval, size_t newlen);
#ifdef CONFIG_PROC_FS
extern int ip_misc_proc_init(void);
#endif

#endif	/* _IP_H */