/* (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> * * 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/types.h>#include <linux/init.h>#include <linux/netfilter.h>#include <linux/ip.h>#include <linux/icmp.h>#include <linux/if.h>#include <linux/netfilter_ipv4/ip_nat.h>#include <linux/netfilter_ipv4/ip_nat_core.h>#include <linux/netfilter_ipv4/ip_nat_rule.h>#include <linux/netfilter_ipv4/ip_nat_protocol.h>static inticmp_in_range(const struct ip_conntrack_tuple *tuple,	      enum ip_nat_manip_type maniptype,	      const union ip_conntrack_manip_proto *min,	      const union ip_conntrack_manip_proto *max){	return (tuple->src.u.icmp.id >= min->icmp.id		&& tuple->src.u.icmp.id <= max->icmp.id);}static inticmp_unique_tuple(struct ip_conntrack_tuple *tuple,		  const struct ip_nat_range *range,		  enum ip_nat_manip_type maniptype,		  const struct ip_conntrack *conntrack){	static u_int16_t id;	unsigned int range_size		= (unsigned int)range->max.icmp.id - range->min.icmp.id + 1;	unsigned int i;	/* If no range specified... */	if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))		range_size = 0xFFFF;	for (i = 0; i < range_size; i++, id++) {		tuple->src.u.icmp.id = range->min.icmp.id + (id % range_size);		if (!ip_nat_used_tuple(tuple, conntrack))			return 1;	}	return 0;}static inticmp_manip_pkt(struct sk_buff **pskb,	       unsigned int hdroff,	       const struct ip_conntrack_manip *manip,	       enum ip_nat_manip_type maniptype){	struct icmphdr *hdr;	if (!skb_ip_make_writable(pskb, hdroff + sizeof(*hdr)))		return 0;	hdr = (void *)(*pskb)->data + hdroff;	hdr->checksum = ip_nat_cheat_check(hdr->un.echo.id ^ 0xFFFF,					    manip->u.icmp.id,					    hdr->checksum);	hdr->un.echo.id = manip->u.icmp.id;	return 1;}static unsigned inticmp_print(char *buffer,	   const struct ip_conntrack_tuple *match,	   const struct ip_conntrack_tuple *mask){	unsigned int len = 0;	if (mask->src.u.icmp.id)		len += sprintf(buffer + len, "id=%u ",			       ntohs(match->src.u.icmp.id));	if (mask->dst.u.icmp.type)		len += sprintf(buffer + len, "type=%u ",			       ntohs(match->dst.u.icmp.type));	if (mask->dst.u.icmp.code)		len += sprintf(buffer + len, "code=%u ",			       ntohs(match->dst.u.icmp.code));	return len;}static unsigned inticmp_print_range(char *buffer, const struct ip_nat_range *range){	if (range->min.icmp.id != 0 || range->max.icmp.id != 0xFFFF)		return sprintf(buffer, "id %u-%u ",			       ntohs(range->min.icmp.id),			       ntohs(range->max.icmp.id));	else return 0;}struct ip_nat_protocol ip_nat_protocol_icmp= { { NULL, NULL }, "ICMP", IPPROTO_ICMP,    icmp_manip_pkt,    icmp_in_range,    icmp_unique_tuple,    icmp_print,    icmp_print_range};