| /* (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 int |
| icmp_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 int |
| icmp_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 int |
| icmp_manip_pkt(struct sk_buff **pskb, |
| unsigned int iphdroff, |
| const struct ip_conntrack_tuple *tuple, |
| enum ip_nat_manip_type maniptype) |
| { |
| struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); |
| struct icmphdr *hdr; |
| unsigned int hdroff = iphdroff + iph->ihl*4; |
| |
| if (!skb_ip_make_writable(pskb, hdroff + sizeof(*hdr))) |
| return 0; |
| |
| hdr = (struct icmphdr *)((*pskb)->data + hdroff); |
| |
| hdr->checksum = ip_nat_cheat_check(hdr->un.echo.id ^ 0xFFFF, |
| tuple->src.u.icmp.id, |
| hdr->checksum); |
| hdr->un.echo.id = tuple->src.u.icmp.id; |
| return 1; |
| } |
| |
| static unsigned int |
| icmp_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 int |
| icmp_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 |
| = { "ICMP", IPPROTO_ICMP, |
| icmp_manip_pkt, |
| icmp_in_range, |
| icmp_unique_tuple, |
| icmp_print, |
| icmp_print_range |
| }; |