/*
 * 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.
 *
 *		INET protocol dispatch tables.
 *
 * Version:	@(#)protocol.c	1.0.5	05/25/93
 *
 * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
 *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 * Fixes:
 *		Alan Cox	: Ahah! udp icmp errors don't work because
 *				  udp_err is never called!
 *		Alan Cox	: Added new fields for init and ready for
 *				  proper fragmentation (_NO_ 4K limits!)
 *		Richard Colella	: Hang on hash collision
 *
 *		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.
 */

#include <asm/segment.h>
#include <asm/system.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/config.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/tcp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/ipip.h>
#include <linux/igmp.h>


#ifdef CONFIG_NET_IPIP

static struct inet_protocol ipip_protocol = 
{
	ipip_rcv,             /* IPIP handler          */
	NULL,                 /* TUNNEL error control    */
	0,                    /* next                 */
	IPPROTO_IPIP,         /* protocol ID          */
	0,                    /* copy                 */
	NULL,                 /* data                 */
	"IPIP"                /* name                 */
};


#endif

static struct inet_protocol tcp_protocol = 
{
	tcp_rcv,		/* TCP handler		*/
	tcp_err,		/* TCP error control	*/  
#if defined(CONFIG_NET_IPIP)
	&ipip_protocol,
#else  
	NULL,			/* next			*/
#endif  
	IPPROTO_TCP,		/* protocol ID		*/
	0,			/* copy			*/
	NULL,			/* data			*/
	"TCP"			/* name			*/
};


static struct inet_protocol udp_protocol = 
{
	udp_rcv,		/* UDP handler		*/
	udp_err,		/* UDP error control	*/
	&tcp_protocol,		/* next			*/
	IPPROTO_UDP,		/* protocol ID		*/
	0,			/* copy			*/
	NULL,			/* data			*/
	"UDP"			/* name			*/
};


static struct inet_protocol icmp_protocol = 
{
	icmp_rcv,		/* ICMP handler		*/
	NULL,			/* ICMP error control	*/
	&udp_protocol,		/* next			*/
	IPPROTO_ICMP,		/* protocol ID		*/
	0,			/* copy			*/
	NULL,			/* data			*/
	"ICMP"			/* name			*/
};

#ifndef CONFIG_IP_MULTICAST
struct inet_protocol *inet_protocol_base = &icmp_protocol;
#else
static struct inet_protocol igmp_protocol = 
{
	igmp_rcv,		/* IGMP handler		*/
	NULL,			/* IGMP error control	*/
	&icmp_protocol,		/* next			*/
	IPPROTO_IGMP,		/* protocol ID		*/
	0,			/* copy			*/
	NULL,			/* data			*/
	"IGMP"			/* name			*/
};

struct inet_protocol *inet_protocol_base = &igmp_protocol;
#endif

struct inet_protocol *inet_protos[MAX_INET_PROTOS] = 
{
	NULL
};


/*
 *	Find a protocol in the protocol tables given its
 *	IP type.
 */

struct inet_protocol *inet_get_protocol(unsigned char prot)
{
	unsigned char hash;
	struct inet_protocol *p;

	hash = prot & (MAX_INET_PROTOS - 1);
	for (p = inet_protos[hash] ; p != NULL; p=p->next) 
	{
		if (p->protocol == prot) 
			return((struct inet_protocol *) p);
	}
	return(NULL);
}

/*
 *	Add a protocol handler to the hash tables
 */

void inet_add_protocol(struct inet_protocol *prot)
{
	unsigned char hash;
	struct inet_protocol *p2;

	hash = prot->protocol & (MAX_INET_PROTOS - 1);
	prot ->next = inet_protos[hash];
	inet_protos[hash] = prot;
	prot->copy = 0;

	/*
	 *	Set the copy bit if we need to. 
	 */
	 
	p2 = (struct inet_protocol *) prot->next;
	while(p2 != NULL) 
	{
		if (p2->protocol == prot->protocol) 
		{
			prot->copy = 1;
			break;
		}
		p2 = (struct inet_protocol *) p2->next;
	}
}

/*
 *	Remove a protocol from the hash tables.
 */
 
int inet_del_protocol(struct inet_protocol *prot)
{
	struct inet_protocol *p;
	struct inet_protocol *lp = NULL;
	unsigned char hash;

	hash = prot->protocol & (MAX_INET_PROTOS - 1);
	if (prot == inet_protos[hash]) 
	{
		inet_protos[hash] = (struct inet_protocol *) inet_protos[hash]->next;
		return(0);
	}

	p = (struct inet_protocol *) inet_protos[hash];
	while(p != NULL) 
	{
		/*
		 * We have to worry if the protocol being deleted is
		 * the last one on the list, then we may need to reset
		 * someone's copied bit.
		 */
		if (p->next != NULL && p->next == prot) 
		{
			/*
			 * if we are the last one with this protocol and
			 * there is a previous one, reset its copy bit.
			 */
			if (p->copy == 0 && lp != NULL) 
				lp->copy = 0;
			p->next = prot->next;
			return(0);
		}
		if (p->next != NULL && p->next->protocol == prot->protocol) 
			lp = p;

		p = (struct inet_protocol *) p->next;
	}
	return(-1);
}