| /* (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/udp.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 |
| udp_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) |
| { |
| u_int16_t port; |
| |
| if (maniptype == IP_NAT_MANIP_SRC) |
| port = tuple->src.u.udp.port; |
| else |
| port = tuple->dst.u.udp.port; |
| |
| return ntohs(port) >= ntohs(min->udp.port) |
| && ntohs(port) <= ntohs(max->udp.port); |
| } |
| |
| static int |
| udp_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 port, *portptr; |
| unsigned int range_size, min, i; |
| |
| if (maniptype == IP_NAT_MANIP_SRC) |
| portptr = &tuple->src.u.udp.port; |
| else |
| portptr = &tuple->dst.u.udp.port; |
| |
| /* If no range specified... */ |
| if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) { |
| /* If it's dst rewrite, can't change port */ |
| if (maniptype == IP_NAT_MANIP_DST) |
| return 0; |
| |
| if (ntohs(*portptr) < 1024) { |
| /* Loose convention: >> 512 is credential passing */ |
| if (ntohs(*portptr)<512) { |
| min = 1; |
| range_size = 511 - min + 1; |
| } else { |
| min = 600; |
| range_size = 1023 - min + 1; |
| } |
| } else { |
| min = 1024; |
| range_size = 65535 - 1024 + 1; |
| } |
| } else { |
| min = ntohs(range->min.udp.port); |
| range_size = ntohs(range->max.udp.port) - min + 1; |
| } |
| |
| for (i = 0; i < range_size; i++, port++) { |
| *portptr = htons(min + port % range_size); |
| if (!ip_nat_used_tuple(tuple, conntrack)) |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int |
| udp_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 udphdr *hdr; |
| unsigned int hdroff = iphdroff + iph->ihl*4; |
| u32 oldip, newip; |
| u16 *portptr, newport; |
| |
| if (!skb_ip_make_writable(pskb, hdroff + sizeof(*hdr))) |
| return 0; |
| |
| iph = (struct iphdr *)((*pskb)->data + iphdroff); |
| hdr = (struct udphdr *)((*pskb)->data + hdroff); |
| |
| if (maniptype == IP_NAT_MANIP_SRC) { |
| /* Get rid of src ip and src pt */ |
| oldip = iph->saddr; |
| newip = tuple->src.ip; |
| newport = tuple->src.u.udp.port; |
| portptr = &hdr->source; |
| } else { |
| /* Get rid of dst ip and dst pt */ |
| oldip = iph->daddr; |
| newip = tuple->dst.ip; |
| newport = tuple->dst.u.udp.port; |
| portptr = &hdr->dest; |
| } |
| if (hdr->check) /* 0 is a special case meaning no checksum */ |
| hdr->check = ip_nat_cheat_check(~oldip, newip, |
| ip_nat_cheat_check(*portptr ^ 0xFFFF, |
| newport, |
| hdr->check)); |
| *portptr = newport; |
| return 1; |
| } |
| |
| static unsigned int |
| udp_print(char *buffer, |
| const struct ip_conntrack_tuple *match, |
| const struct ip_conntrack_tuple *mask) |
| { |
| unsigned int len = 0; |
| |
| if (mask->src.u.udp.port) |
| len += sprintf(buffer + len, "srcpt=%u ", |
| ntohs(match->src.u.udp.port)); |
| |
| |
| if (mask->dst.u.udp.port) |
| len += sprintf(buffer + len, "dstpt=%u ", |
| ntohs(match->dst.u.udp.port)); |
| |
| return len; |
| } |
| |
| static unsigned int |
| udp_print_range(char *buffer, const struct ip_nat_range *range) |
| { |
| if (range->min.udp.port != 0 || range->max.udp.port != 0xFFFF) { |
| if (range->min.udp.port == range->max.udp.port) |
| return sprintf(buffer, "port %u ", |
| ntohs(range->min.udp.port)); |
| else |
| return sprintf(buffer, "ports %u-%u ", |
| ntohs(range->min.udp.port), |
| ntohs(range->max.udp.port)); |
| } |
| else return 0; |
| } |
| |
| struct ip_nat_protocol ip_nat_protocol_udp |
| = { "UDP", IPPROTO_UDP, |
| udp_manip_pkt, |
| udp_in_range, |
| udp_unique_tuple, |
| udp_print, |
| udp_print_range |
| }; |