/* * 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!) * *		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/socket.h>#include <linux/in.h>#include "inet.h"#include "dev.h"#include "ip.h"#include "protocol.h"#include "tcp.h"#include "skbuff.h"#include "sock.h"#include "icmp.h"#include "udp.h"static struct inet_protocol tcp_protocol = {  tcp_rcv,		/* TCP handler		*/  NULL,			/* No fragment handler (and won't be for a long time) */  tcp_err,		/* TCP error control	*/  NULL,			/* next			*/  IPPROTO_TCP,		/* protocol ID		*/  0,			/* copy			*/  NULL,			/* data			*/  "TCP"			/* name			*/};static struct inet_protocol udp_protocol = {  udp_rcv,		/* UDP handler		*/  NULL,			/* Will be UDP fraglist 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 never fragments anyway */  NULL,			/* ICMP error control	*/  &udp_protocol,	/* next			*/  IPPROTO_ICMP,		/* protocol ID		*/  0,			/* copy			*/  NULL,			/* data			*/  "ICMP"		/* name			*/};struct inet_protocol *inet_protocol_base = &icmp_protocol;struct inet_protocol *inet_protos[MAX_INET_PROTOS] = {  NULL};struct inet_protocol *inet_get_protocol(unsigned char prot){  unsigned char hash;  struct inet_protocol *p;  DPRINTF((DBG_PROTO, "get_protocol (%d)\n ", prot));  hash = prot & (MAX_INET_PROTOS - 1);  for (p = inet_protos[hash] ; p != NULL; p=p->next) {	DPRINTF((DBG_PROTO, "trying protocol %d\n", p->protocol));	if (p->protocol == prot) return((struct inet_protocol *) p);  }  return(NULL);}voidinet_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 *) prot->next;  }}intinet_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	 * someones 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);}