/* ipv6header match - matches IPv6 packets based   on whether they contain certain headers *//* Original idea: Brad Chapman  * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> *//* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */#include <linux/module.h>#include <linux/skbuff.h>#include <linux/ipv6.h>#include <linux/types.h>#include <net/checksum.h>#include <net/ipv6.h>#include <linux/netfilter_ipv6/ip6_tables.h>#include <linux/netfilter_ipv6/ip6t_ipv6header.h>MODULE_LICENSE("GPL");MODULE_DESCRIPTION("IPv6 headers match");MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");static intipv6header_match(const struct sk_buff *skb,		 const struct net_device *in,		 const struct net_device *out,		 const void *matchinfo,		 int offset,		 const void *protohdr,		 u_int16_t datalen,		 int *hotdrop){	const struct ip6t_ipv6header_info *info = matchinfo;	unsigned int temp;	int len;	u8 nexthdr;	unsigned int ptr;	/* Make sure this isn't an evil packet */	/* type of the 1st exthdr */	nexthdr = skb->nh.ipv6h->nexthdr;	/* pointer to the 1st exthdr */	ptr = sizeof(struct ipv6hdr);	/* available length */	len = skb->len - ptr;	temp = 0;        while (ip6t_ext_hdr(nexthdr)) {        	struct ipv6_opt_hdr *hdr;        	int hdrlen;		/* Is there enough space for the next ext header? */                if (len < (int)sizeof(struct ipv6_opt_hdr))                        return 0;		/* No more exthdr -> evaluate */                if (nexthdr == NEXTHDR_NONE) {			temp |= MASK_NONE;			break;		}		/* ESP -> evaluate */                if (nexthdr == NEXTHDR_ESP) {			temp |= MASK_ESP;			break;		}		hdr=(struct ipv6_opt_hdr *)skb->data+ptr;		/* Calculate the header length */                if (nexthdr == NEXTHDR_FRAGMENT) {                        hdrlen = 8;                } else if (nexthdr == NEXTHDR_AUTH)                        hdrlen = (hdr->hdrlen+2)<<2;                else                        hdrlen = ipv6_optlen(hdr);		/* set the flag */		switch (nexthdr){			case NEXTHDR_HOP:				temp |= MASK_HOPOPTS;				break;			case NEXTHDR_ROUTING:				temp |= MASK_ROUTING;				break;			case NEXTHDR_FRAGMENT:				temp |= MASK_FRAGMENT;				break;			case NEXTHDR_AUTH:				temp |= MASK_AH;				break;			case NEXTHDR_DEST:				temp |= MASK_DSTOPTS;				break;			default:				return 0;				break;		}                nexthdr = hdr->nexthdr;                len -= hdrlen;                ptr += hdrlen;		if (ptr > skb->len)			break;        }	if ( (nexthdr != NEXTHDR_NONE ) && (nexthdr != NEXTHDR_ESP) )		temp |= MASK_PROTO;	if (info->modeflag)		return (!( (temp & info->matchflags)			^ info->matchflags) ^ info->invflags);	else		return (!( temp ^ info->matchflags) ^ info->invflags);}static intipv6header_checkentry(const char *tablename,		      const struct ip6t_ip6 *ip,		      void *matchinfo,		      unsigned int matchsize,		      unsigned int hook_mask){	/* Check for obvious errors */	/* This match is valid in all hooks! */	if (matchsize != IP6T_ALIGN(sizeof(struct ip6t_ipv6header_info)))		return 0;	return 1;}static struct ip6t_match ip6t_ipv6header_match = {	.name		= "ipv6header",	.match		= &ipv6header_match,	.checkentry	= &ipv6header_checkentry,	.destroy	= NULL,	.me		= THIS_MODULE,};static int  __init ipv6header_init(void){	return ip6t_register_match(&ip6t_ipv6header_match);}static void __exit ipv6header_exit(void){	ip6t_unregister_match(&ip6t_ipv6header_match);}module_init(ipv6header_init);module_exit(ipv6header_exit);