/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/udp.h>
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#include <linux/netfilter.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_core.h>
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#include <net/netfilter/nf_nat_l3proto.h>
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#include <net/netfilter/nf_nat_l4proto.h>
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static u16 udp_port_rover;
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static void
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udp_unique_tuple(const struct nf_nat_l3proto *l3proto,
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struct nf_conntrack_tuple *tuple,
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const struct nf_nat_range *range,
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enum nf_nat_manip_type maniptype,
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const struct nf_conn *ct)
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{
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nf_nat_l4proto_unique_tuple(l3proto, tuple, range, maniptype, ct,
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&udp_port_rover);
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}
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static bool
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udp_manip_pkt(struct sk_buff *skb,
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const struct nf_nat_l3proto *l3proto,
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unsigned int iphdroff, unsigned int hdroff,
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const struct nf_conntrack_tuple *tuple,
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enum nf_nat_manip_type maniptype)
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{
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struct udphdr *hdr;
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__be16 *portptr, newport;
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if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
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return false;
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hdr = (struct udphdr *)(skb->data + hdroff);
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if (maniptype == NF_NAT_MANIP_SRC) {
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/* Get rid of src port */
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newport = tuple->src.u.udp.port;
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portptr = &hdr->source;
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} else {
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/* Get rid of dst port */
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newport = tuple->dst.u.udp.port;
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portptr = &hdr->dest;
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}
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if (hdr->check || skb->ip_summed == CHECKSUM_PARTIAL) {
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l3proto->csum_update(skb, iphdroff, &hdr->check,
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tuple, maniptype);
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inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
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false);
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if (!hdr->check)
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hdr->check = CSUM_MANGLED_0;
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}
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*portptr = newport;
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return true;
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}
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const struct nf_nat_l4proto nf_nat_l4proto_udp = {
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.l4proto = IPPROTO_UDP,
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.manip_pkt = udp_manip_pkt,
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.in_range = nf_nat_l4proto_in_range,
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.unique_tuple = udp_unique_tuple,
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
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.nlattr_to_range = nf_nat_l4proto_nlattr_to_range,
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#endif
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};
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