1/*
2 * INET		An implementation of the TCP/IP protocol suite for the LINUX
3 *		operating system.  INET is implemented using the  BSD Socket
4 *		interface as the means of communication with the user level.
5 *
6 *		Definitions for the IP module.
7 *
8 * Version:	@(#)ip.h	1.0.2	05/07/93
9 *
10 * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
11 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *		Alan Cox, <gw4pts@gw4pts.ampr.org>
13 *
14 * Changes:
15 *		Mike McLagan    :       Routing by source
16 *
17 *		This program is free software; you can redistribute it and/or
18 *		modify it under the terms of the GNU General Public License
19 *		as published by the Free Software Foundation; either version
20 *		2 of the License, or (at your option) any later version.
21 */
22#ifndef _IP_H
23#define _IP_H
24
25#include <linux/config.h>
26#include <linux/types.h>
27#include <linux/socket.h>
28#include <linux/ip.h>
29#include <linux/netdevice.h>
30#include <linux/inetdevice.h>
31#include <linux/in_route.h>
32#include <net/route.h>
33#include <net/arp.h>
34
35#ifndef _SNMP_H
36#include <net/snmp.h>
37#endif
38
39#include <net/sock.h>	/* struct sock */
40
41struct inet_skb_parm
42{
43	struct ip_options	opt;		/* Compiled IP options		*/
44	unsigned char		flags;
45
46#define IPSKB_MASQUERADED	1
47#define IPSKB_TRANSLATED	2
48#define IPSKB_FORWARDED		4
49};
50
51struct ipcm_cookie
52{
53	u32			addr;
54	int			oif;
55	struct ip_options	*opt;
56};
57
58#define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
59
60struct ip_ra_chain
61{
62	struct ip_ra_chain	*next;
63	struct sock		*sk;
64	void			(*destructor)(struct sock *);
65};
66
67extern struct ip_ra_chain *ip_ra_chain;
68extern rwlock_t ip_ra_lock;
69
70/* IP flags. */
71#define IP_CE		0x8000		/* Flag: "Congestion"		*/
72#define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
73#define IP_MF		0x2000		/* Flag: "More Fragments"	*/
74#define IP_OFFSET	0x1FFF		/* "Fragment Offset" part	*/
75
76#define IP_FRAG_TIME	(30 * HZ)		/* fragment lifetime	*/
77
78extern void		ip_mc_dropsocket(struct sock *);
79extern void		ip_mc_dropdevice(struct net_device *dev);
80extern int		ip_mc_procinfo(char *, char **, off_t, int);
81
82/*
83 *	Functions provided by ip.c
84 */
85
86extern int		ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
87					      u32 saddr, u32 daddr,
88					      struct ip_options *opt);
89extern int		ip_rcv(struct sk_buff *skb, struct net_device *dev,
90			       struct packet_type *pt);
91extern int		ip_local_deliver(struct sk_buff *skb);
92extern int		ip_mr_input(struct sk_buff *skb);
93extern int		ip_output(struct sk_buff *skb);
94extern int		ip_mc_output(struct sk_buff *skb);
95extern int		ip_fragment(struct sk_buff *skb, int (*out)(struct sk_buff*));
96extern int		ip_do_nat(struct sk_buff *skb);
97extern void		ip_send_check(struct iphdr *ip);
98extern int		ip_queue_xmit(struct sk_buff *skb);
99extern void		ip_init(void);
100extern int		ip_build_xmit(struct sock *sk,
101				      int getfrag (const void *,
102						   char *,
103						   unsigned int,
104						   unsigned int),
105				      const void *frag,
106				      unsigned length,
107				      struct ipcm_cookie *ipc,
108				      struct rtable *rt,
109				      int flags);
110
111/*
112 *	Map a multicast IP onto multicast MAC for type Token Ring.
113 *      This conforms to RFC1469 Option 2 Multicasting i.e.
114 *      using a functional address to transmit / receive
115 *      multicast packets.
116 */
117
118static inline void ip_tr_mc_map(u32 addr, char *buf)
119{
120	buf[0]=0xC0;
121	buf[1]=0x00;
122	buf[2]=0x00;
123	buf[3]=0x04;
124	buf[4]=0x00;
125	buf[5]=0x00;
126}
127
128struct ip_reply_arg {
129	struct iovec iov[2];
130	int          n_iov;    /* redundant */
131	u32 	     csum;
132	int	     csumoffset; /* u16 offset of csum in iov[0].iov_base */
133				 /* -1 if not needed */
134};
135
136void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
137		   unsigned int len);
138
139extern __inline__ int ip_finish_output(struct sk_buff *skb);
140
141struct ipv4_config
142{
143	int	log_martians;
144	int	autoconfig;
145	int	no_pmtu_disc;
146};
147
148extern struct ipv4_config ipv4_config;
149extern struct ip_mib	ip_statistics[NR_CPUS*2];
150#define IP_INC_STATS(field)		SNMP_INC_STATS(ip_statistics, field)
151#define IP_INC_STATS_BH(field)		SNMP_INC_STATS_BH(ip_statistics, field)
152#define IP_INC_STATS_USER(field) 	SNMP_INC_STATS_USER(ip_statistics, field)
153extern struct linux_mib	net_statistics[NR_CPUS*2];
154#define NET_INC_STATS(field)		SNMP_INC_STATS(net_statistics, field)
155#define NET_INC_STATS_BH(field)		SNMP_INC_STATS_BH(net_statistics, field)
156#define NET_INC_STATS_USER(field) 	SNMP_INC_STATS_USER(net_statistics, field)
157
158extern int sysctl_local_port_range[2];
159extern int sysctl_ip_default_ttl;
160
161#ifdef CONFIG_INET
162static inline int ip_send(struct sk_buff *skb)
163{
164	if (skb->len > skb->dst->pmtu)
165		return ip_fragment(skb, ip_finish_output);
166	else
167		return ip_finish_output(skb);
168}
169
170/* The function in 2.2 was invalid, producing wrong result for
171 * check=0xFEFF. It was noticed by Arthur Skawina _year_ ago. --ANK(000625) */
172static inline
173int ip_decrease_ttl(struct iphdr *iph)
174{
175	u32 check = iph->check;
176	check += __constant_htons(0x0100);
177	iph->check = check + (check>=0xFFFF);
178	return --iph->ttl;
179}
180
181static inline
182int ip_dont_fragment(struct sock *sk, struct dst_entry *dst)
183{
184	return (sk->protinfo.af_inet.pmtudisc == IP_PMTUDISC_DO ||
185		(sk->protinfo.af_inet.pmtudisc == IP_PMTUDISC_WANT &&
186		 !(dst->mxlock&(1<<RTAX_MTU))));
187}
188
189extern void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst);
190
191static inline void ip_select_ident(struct iphdr *iph, struct dst_entry *dst, struct sock *sk)
192{
193	if (iph->frag_off&__constant_htons(IP_DF)) {
194		/* This is only to work around buggy Windows95/2000
195		 * VJ compression implementations.  If the ID field
196		 * does not change, they drop every other packet in
197		 * a TCP stream using header compression.
198		 */
199		iph->id = ((sk && sk->daddr) ? htons(sk->protinfo.af_inet.id++) : 0);
200	} else
201		__ip_select_ident(iph, dst);
202}
203
204/*
205 *	Map a multicast IP onto multicast MAC for type ethernet.
206 */
207
208static inline void ip_eth_mc_map(u32 addr, char *buf)
209{
210	addr=ntohl(addr);
211	buf[0]=0x01;
212	buf[1]=0x00;
213	buf[2]=0x5e;
214	buf[5]=addr&0xFF;
215	addr>>=8;
216	buf[4]=addr&0xFF;
217	addr>>=8;
218	buf[3]=addr&0x7F;
219}
220
221#endif
222
223extern int	ip_call_ra_chain(struct sk_buff *skb);
224
225/*
226 *	Functions provided by ip_fragment.o
227 */
228
229struct sk_buff *ip_defrag(struct sk_buff *skb);
230extern int ip_frag_nqueues;
231extern atomic_t ip_frag_mem;
232
233/*
234 *	Functions provided by ip_forward.c
235 */
236
237extern int ip_forward(struct sk_buff *skb);
238extern int ip_net_unreachable(struct sk_buff *skb);
239
240/*
241 *	Functions provided by ip_options.c
242 */
243
244extern void ip_options_build(struct sk_buff *skb, struct ip_options *opt, u32 daddr, struct rtable *rt, int is_frag);
245extern int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb);
246extern void ip_options_fragment(struct sk_buff *skb);
247extern int ip_options_compile(struct ip_options *opt, struct sk_buff *skb);
248extern int ip_options_get(struct ip_options **optp, unsigned char *data, int optlen, int user);
249extern void ip_options_undo(struct ip_options * opt);
250extern void ip_forward_options(struct sk_buff *skb);
251extern int ip_options_rcv_srr(struct sk_buff *skb);
252
253/*
254 *	Functions provided by ip_sockglue.c
255 */
256
257extern void	ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
258extern int	ip_cmsg_send(struct msghdr *msg, struct ipcm_cookie *ipc);
259extern int	ip_setsockopt(struct sock *sk, int level, int optname, char *optval, int optlen);
260extern int	ip_getsockopt(struct sock *sk, int level, int optname, char *optval, int *optlen);
261extern int	ip_ra_control(struct sock *sk, unsigned char on, void (*destructor)(struct sock *));
262
263extern int 	ip_recv_error(struct sock *sk, struct msghdr *msg, int len);
264extern void	ip_icmp_error(struct sock *sk, struct sk_buff *skb, int err,
265			      u16 port, u32 info, u8 *payload);
266extern void	ip_local_error(struct sock *sk, int err, u32 daddr, u16 dport,
267			       u32 info);
268
269#endif	/* _IP_H */
270