// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* ip_vs_proto_udp.c: UDP load balancing support for IPVS
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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* Julian Anastasov <ja@ssi.bg>
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*
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* Changes: Hans Schillstrom <hans.schillstrom@ericsson.com>
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* Network name space (netns) aware.
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*/
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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/kernel.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/udp.h>
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#include <linux/indirect_call_wrapper.h>
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#include <net/ip_vs.h>
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#include <net/ip.h>
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#include <net/ip6_checksum.h>
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static int
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udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
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static int
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udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
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struct ip_vs_proto_data *pd,
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int *verdict, struct ip_vs_conn **cpp,
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struct ip_vs_iphdr *iph)
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{
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struct ip_vs_service *svc;
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struct udphdr _udph, *uh;
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__be16 _ports[2], *ports = NULL;
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if (likely(!ip_vs_iph_icmp(iph))) {
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/* IPv6 fragments, only first fragment will hit this */
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uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
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if (uh)
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ports = &uh->source;
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} else {
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ports = skb_header_pointer(
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skb, iph->len, sizeof(_ports), &_ports);
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}
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if (!ports) {
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*verdict = NF_DROP;
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return 0;
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}
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if (likely(!ip_vs_iph_inverse(iph)))
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svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
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&iph->daddr, ports[1]);
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else
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svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
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&iph->saddr, ports[0]);
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if (svc) {
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int ignored;
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if (ip_vs_todrop(ipvs)) {
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/*
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* It seems that we are very loaded.
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* We have to drop this packet :(
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*/
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*verdict = NF_DROP;
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return 0;
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}
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/*
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* Let the virtual server select a real server for the
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* incoming connection, and create a connection entry.
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*/
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*cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
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if (!*cpp && ignored <= 0) {
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if (!ignored)
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*verdict = ip_vs_leave(svc, skb, pd, iph);
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else
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*verdict = NF_DROP;
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return 0;
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}
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}
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/* NF_ACCEPT */
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return 1;
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}
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static inline void
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udp_fast_csum_update(int af, struct udphdr *uhdr,
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const union nf_inet_addr *oldip,
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const union nf_inet_addr *newip,
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__be16 oldport, __be16 newport)
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{
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#ifdef CONFIG_IP_VS_IPV6
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if (af == AF_INET6)
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uhdr->check =
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csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
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ip_vs_check_diff2(oldport, newport,
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~csum_unfold(uhdr->check))));
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else
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#endif
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uhdr->check =
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csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
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ip_vs_check_diff2(oldport, newport,
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~csum_unfold(uhdr->check))));
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if (!uhdr->check)
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uhdr->check = CSUM_MANGLED_0;
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}
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static inline void
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udp_partial_csum_update(int af, struct udphdr *uhdr,
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const union nf_inet_addr *oldip,
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const union nf_inet_addr *newip,
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__be16 oldlen, __be16 newlen)
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{
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#ifdef CONFIG_IP_VS_IPV6
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if (af == AF_INET6)
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uhdr->check =
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~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
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ip_vs_check_diff2(oldlen, newlen,
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csum_unfold(uhdr->check))));
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else
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#endif
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uhdr->check =
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~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
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ip_vs_check_diff2(oldlen, newlen,
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csum_unfold(uhdr->check))));
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}
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INDIRECT_CALLABLE_SCOPE int
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udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
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struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
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{
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struct udphdr *udph;
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unsigned int udphoff = iph->len;
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bool payload_csum = false;
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int oldlen;
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#ifdef CONFIG_IP_VS_IPV6
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if (cp->af == AF_INET6 && iph->fragoffs)
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return 1;
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#endif
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oldlen = skb->len - udphoff;
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/* csum_check requires unshared skb */
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if (skb_ensure_writable(skb, udphoff + sizeof(*udph)))
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return 0;
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if (unlikely(cp->app != NULL)) {
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int ret;
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/* Some checks before mangling */
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if (!udp_csum_check(cp->af, skb, pp))
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return 0;
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/*
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* Call application helper if needed
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*/
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if (!(ret = ip_vs_app_pkt_out(cp, skb, iph)))
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return 0;
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/* ret=2: csum update is needed after payload mangling */
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if (ret == 1)
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oldlen = skb->len - udphoff;
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else
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payload_csum = true;
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}
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udph = (void *)skb_network_header(skb) + udphoff;
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udph->source = cp->vport;
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/*
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* Adjust UDP checksums
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*/
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if (skb->ip_summed == CHECKSUM_PARTIAL) {
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udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
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htons(oldlen),
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htons(skb->len - udphoff));
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} else if (!payload_csum && (udph->check != 0)) {
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/* Only port and addr are changed, do fast csum update */
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udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
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cp->dport, cp->vport);
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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skb->ip_summed = cp->app ?
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CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
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} else {
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/* full checksum calculation */
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udph->check = 0;
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skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
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#ifdef CONFIG_IP_VS_IPV6
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if (cp->af == AF_INET6)
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udph->check = csum_ipv6_magic(&cp->vaddr.in6,
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&cp->caddr.in6,
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skb->len - udphoff,
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cp->protocol, skb->csum);
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else
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#endif
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udph->check = csum_tcpudp_magic(cp->vaddr.ip,
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cp->caddr.ip,
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skb->len - udphoff,
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cp->protocol,
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skb->csum);
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if (udph->check == 0)
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udph->check = CSUM_MANGLED_0;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
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pp->name, udph->check,
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(char*)&(udph->check) - (char*)udph);
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}
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return 1;
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}
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static int
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udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
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struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
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{
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struct udphdr *udph;
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unsigned int udphoff = iph->len;
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bool payload_csum = false;
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int oldlen;
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#ifdef CONFIG_IP_VS_IPV6
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if (cp->af == AF_INET6 && iph->fragoffs)
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return 1;
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#endif
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oldlen = skb->len - udphoff;
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/* csum_check requires unshared skb */
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if (skb_ensure_writable(skb, udphoff + sizeof(*udph)))
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return 0;
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if (unlikely(cp->app != NULL)) {
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int ret;
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/* Some checks before mangling */
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if (!udp_csum_check(cp->af, skb, pp))
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return 0;
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/*
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* Attempt ip_vs_app call.
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* It will fix ip_vs_conn
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*/
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if (!(ret = ip_vs_app_pkt_in(cp, skb, iph)))
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return 0;
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/* ret=2: csum update is needed after payload mangling */
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if (ret == 1)
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oldlen = skb->len - udphoff;
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else
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payload_csum = true;
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}
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udph = (void *)skb_network_header(skb) + udphoff;
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udph->dest = cp->dport;
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/*
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* Adjust UDP checksums
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*/
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if (skb->ip_summed == CHECKSUM_PARTIAL) {
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udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
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htons(oldlen),
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htons(skb->len - udphoff));
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} else if (!payload_csum && (udph->check != 0)) {
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/* Only port and addr are changed, do fast csum update */
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udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
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cp->vport, cp->dport);
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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skb->ip_summed = cp->app ?
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CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
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} else {
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/* full checksum calculation */
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udph->check = 0;
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skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
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#ifdef CONFIG_IP_VS_IPV6
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if (cp->af == AF_INET6)
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udph->check = csum_ipv6_magic(&cp->caddr.in6,
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&cp->daddr.in6,
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skb->len - udphoff,
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cp->protocol, skb->csum);
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else
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#endif
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udph->check = csum_tcpudp_magic(cp->caddr.ip,
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cp->daddr.ip,
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skb->len - udphoff,
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cp->protocol,
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skb->csum);
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if (udph->check == 0)
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udph->check = CSUM_MANGLED_0;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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}
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return 1;
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}
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static int
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udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
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{
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struct udphdr _udph, *uh;
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unsigned int udphoff;
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#ifdef CONFIG_IP_VS_IPV6
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if (af == AF_INET6)
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udphoff = sizeof(struct ipv6hdr);
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else
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#endif
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udphoff = ip_hdrlen(skb);
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uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
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if (uh == NULL)
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return 0;
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if (uh->check != 0) {
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switch (skb->ip_summed) {
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case CHECKSUM_NONE:
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skb->csum = skb_checksum(skb, udphoff,
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skb->len - udphoff, 0);
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fallthrough;
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case CHECKSUM_COMPLETE:
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#ifdef CONFIG_IP_VS_IPV6
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if (af == AF_INET6) {
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if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
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&ipv6_hdr(skb)->daddr,
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skb->len - udphoff,
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ipv6_hdr(skb)->nexthdr,
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skb->csum)) {
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IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
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"Failed checksum for");
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return 0;
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}
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} else
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#endif
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if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr,
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skb->len - udphoff,
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ip_hdr(skb)->protocol,
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skb->csum)) {
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IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
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"Failed checksum for");
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return 0;
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}
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break;
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default:
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/* No need to checksum. */
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break;
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}
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}
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return 1;
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}
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static inline __u16 udp_app_hashkey(__be16 port)
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{
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return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
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& UDP_APP_TAB_MASK;
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}
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static int udp_register_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
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{
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struct ip_vs_app *i;
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__u16 hash;
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__be16 port = inc->port;
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int ret = 0;
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struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
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hash = udp_app_hashkey(port);
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list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) {
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if (i->port == port) {
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ret = -EEXIST;
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goto out;
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}
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}
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list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]);
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atomic_inc(&pd->appcnt);
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out:
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return ret;
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}
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static void
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udp_unregister_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
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{
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struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
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atomic_dec(&pd->appcnt);
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list_del_rcu(&inc->p_list);
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}
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static int udp_app_conn_bind(struct ip_vs_conn *cp)
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{
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struct netns_ipvs *ipvs = cp->ipvs;
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int hash;
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struct ip_vs_app *inc;
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int result = 0;
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/* Default binding: bind app only for NAT */
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if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
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return 0;
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/* Lookup application incarnations and bind the right one */
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hash = udp_app_hashkey(cp->vport);
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list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) {
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if (inc->port == cp->vport) {
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if (unlikely(!ip_vs_app_inc_get(inc)))
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break;
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IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
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"%s:%u to app %s on port %u\n",
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__func__,
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IP_VS_DBG_ADDR(cp->af, &cp->caddr),
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ntohs(cp->cport),
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IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
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ntohs(cp->vport),
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inc->name, ntohs(inc->port));
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cp->app = inc;
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if (inc->init_conn)
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result = inc->init_conn(inc, cp);
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break;
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}
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}
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return result;
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}
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static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
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[IP_VS_UDP_S_NORMAL] = 5*60*HZ,
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[IP_VS_UDP_S_LAST] = 2*HZ,
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};
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static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
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[IP_VS_UDP_S_NORMAL] = "UDP",
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[IP_VS_UDP_S_LAST] = "BUG!",
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};
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static const char * udp_state_name(int state)
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{
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if (state >= IP_VS_UDP_S_LAST)
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return "ERR!";
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return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
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}
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static void
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udp_state_transition(struct ip_vs_conn *cp, int direction,
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const struct sk_buff *skb,
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struct ip_vs_proto_data *pd)
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{
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if (unlikely(!pd)) {
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pr_err("UDP no ns data\n");
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return;
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}
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cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL];
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if (direction == IP_VS_DIR_OUTPUT)
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ip_vs_control_assure_ct(cp);
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}
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static int __udp_init(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
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{
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ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE);
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pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts,
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sizeof(udp_timeouts));
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if (!pd->timeout_table)
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return -ENOMEM;
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return 0;
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}
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static void __udp_exit(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
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{
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kfree(pd->timeout_table);
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}
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struct ip_vs_protocol ip_vs_protocol_udp = {
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.name = "UDP",
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.protocol = IPPROTO_UDP,
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.num_states = IP_VS_UDP_S_LAST,
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.dont_defrag = 0,
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.init = NULL,
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.exit = NULL,
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.init_netns = __udp_init,
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.exit_netns = __udp_exit,
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.conn_schedule = udp_conn_schedule,
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.conn_in_get = ip_vs_conn_in_get_proto,
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.conn_out_get = ip_vs_conn_out_get_proto,
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.snat_handler = udp_snat_handler,
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.dnat_handler = udp_dnat_handler,
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.state_transition = udp_state_transition,
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.state_name = udp_state_name,
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.register_app = udp_register_app,
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.unregister_app = udp_unregister_app,
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.app_conn_bind = udp_app_conn_bind,
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.debug_packet = ip_vs_tcpudp_debug_packet,
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.timeout_change = NULL,
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};
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