text: /* SPDX-License-Identifier: GPL-2.0 */
  /*
   * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
   */
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(3, 18, 0)
  #define udp_sock_create4 udp_sock_create
  #define udp_sock_create6 udp_sock_create
  #include <linux/socket.h>
  #include <linux/if.h>
  #include <linux/in.h>
  #include <net/ip_tunnels.h>
  #include <net/udp.h>
  #include <net/inet_common.h>
  #if IS_ENABLED(CONFIG_IPV6)
  #include <linux/in6.h>
  #include <net/ipv6.h>
  #include <net/addrconf.h>
  #include <net/ip6_checksum.h>
  #include <net/ip6_tunnel.h>
  #endif
  static inline void __compat_fake_destructor(struct sk_buff *skb)
  {
  }
  typedef int (*udp_tunnel_encap_rcv_t)(struct sock *sk, struct sk_buff *skb);
  struct udp_tunnel_sock_cfg {
          void *sk_user_data;
          __u8  encap_type;
          udp_tunnel_encap_rcv_t encap_rcv;
  };
  /* This is global so, uh, only one real call site... This is the kind of horrific hack you'd expect to see in compat code. */
  static udp_tunnel_encap_rcv_t encap_rcv = NULL;
  static void __compat_sk_data_ready(struct sock *sk)
  {
  	struct sk_buff *skb;
  	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
  		skb_orphan(skb);
  		sk_mem_reclaim(sk);
  		encap_rcv(sk, skb);
  	}
  }
  static inline void setup_udp_tunnel_sock(struct net *net, struct socket *sock,
                             struct udp_tunnel_sock_cfg *cfg)
  {
  	struct sock *sk = sock->sk;
  	inet_sk(sk)->mc_loop = 0;
  	encap_rcv = cfg->encap_rcv;
  	rcu_assign_sk_user_data(sk, cfg->sk_user_data);
  	sk->sk_data_ready = __compat_sk_data_ready;
  }
  static inline void udp_tunnel_sock_release(struct socket *sock)
  {
  	rcu_assign_sk_user_data(sock->sk, NULL);
  	kernel_sock_shutdown(sock, SHUT_RDWR);
  	sk_release_kernel(sock->sk);
  }
  static inline int udp_tunnel_xmit_skb(struct socket *sock, struct rtable *rt,
                          struct sk_buff *skb, __be32 src, __be32 dst,
                          __u8 tos, __u8 ttl, __be16 df, __be16 src_port,
                          __be16 dst_port, bool xnet)
  {
  	struct udphdr *uh;
  	__skb_push(skb, sizeof(*uh));
  	skb_reset_transport_header(skb);
  	uh = udp_hdr(skb);
  	uh->dest = dst_port;
  	uh->source = src_port;
  	uh->len = htons(skb->len);
  	udp_set_csum(sock->sk->sk_no_check_tx, skb, src, dst, skb->len);
  	return iptunnel_xmit(sock->sk, rt, skb, src, dst, IPPROTO_UDP,
  			     tos, ttl, df, xnet);
  }
  #if IS_ENABLED(CONFIG_IPV6)
  static inline int udp_tunnel6_xmit_skb(struct socket *sock, struct dst_entry *dst,
                           struct sk_buff *skb, struct net_device *dev,
                           struct in6_addr *saddr, struct in6_addr *daddr,
                           __u8 prio, __u8 ttl, __be16 src_port,
                           __be16 dst_port)
  {
  	struct udphdr *uh;
  	struct ipv6hdr *ip6h;
  	struct sock *sk = sock->sk;
  	__skb_push(skb, sizeof(*uh));
  	skb_reset_transport_header(skb);
  	uh = udp_hdr(skb);
  	uh->dest = dst_port;
  	uh->source = src_port;
  	uh->len = htons(skb->len);
  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
  	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED
  			    | IPSKB_REROUTED);
  	skb_dst_set(skb, dst);
  	udp6_set_csum(udp_get_no_check6_tx(sk), skb, &inet6_sk(sk)->saddr,
  	              &sk->sk_v6_daddr, skb->len);
  	__skb_push(skb, sizeof(*ip6h));
  	skb_reset_network_header(skb);
  	ip6h		  = ipv6_hdr(skb);
  	ip6_flow_hdr(ip6h, prio, htonl(0));
  	ip6h->payload_len = htons(skb->len);
  	ip6h->nexthdr     = IPPROTO_UDP;
  	ip6h->hop_limit   = ttl;
  	ip6h->daddr	  = *daddr;
  	ip6h->saddr	  = *saddr;
  	ip6tunnel_xmit(skb, dev);
  	return 0;
  }
  #endif
  #endif
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
  #include <linux/in.h>
  #include <linux/in6.h>
  #include <linux/udp.h>
  #include <linux/skbuff.h>
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  #define udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) do { struct net_device *dev__ = (c)->dev; int ret__; ret__ = udp_tunnel_xmit_skb((b)->sk_socket, a, c, d, e, f, g, h, i, j, k); if (ret__) iptunnel_xmit_stats(ret__ - 8, &dev__->stats, dev__->tstats); } while (0)
  #if IS_ENABLED(CONFIG_IPV6)
  #define udp_tunnel6_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) udp_tunnel6_xmit_skb((b)->sk_socket, a, c, d, e, f, g, h, j, k);
  #endif
  #elif LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  #if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 18, 0)
  static inline void __compat_fake_destructor(struct sk_buff *skb)
  {
  }
  #endif
  #define udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) do { struct net_device *dev__ = (c)->dev; int ret__; if (!(c)->destructor) (c)->destructor = __compat_fake_destructor; if (!(c)->sk) (c)->sk = (b); ret__ = udp_tunnel_xmit_skb(a, c, d, e, f, g, h, i, j, k, l); if (ret__) iptunnel_xmit_stats(ret__ - 8, &dev__->stats, dev__->tstats); } while (0)
  #if IS_ENABLED(CONFIG_IPV6)
  #define udp_tunnel6_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) do { if (!(c)->destructor) (c)->destructor = __compat_fake_destructor; if (!(c)->sk) (c)->sk = (b); udp_tunnel6_xmit_skb(a, c, d, e, f, g, h, j, k, l); } while(0)
  #endif
  #else
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  #define udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) do { struct net_device *dev__ = (c)->dev; int ret__ = udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l); if (ret__) iptunnel_xmit_stats(ret__ - 8, &dev__->stats, dev__->tstats); } while (0)
  #endif
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 3, 0)
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  #define udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) do { struct net_device *dev__ = (c)->dev; int ret__ = udp_tunnel_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l); iptunnel_xmit_stats(ret__, &dev__->stats, dev__->tstats); } while (0)
  #endif
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 6, 0) && IS_ENABLED(CONFIG_IPV6) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  #define udp_tunnel6_xmit_skb(a, b, c, d, e, f, g, h, i, j, k, l) udp_tunnel6_xmit_skb(a, b, c, d, e, f, g, h, j, k, l)
  #endif
  
  #endif
  
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 17, 0)
  #include <linux/skbuff.h>
  #include <linux/if.h>
  #include <net/udp_tunnel.h>
  struct __compat_udp_port_cfg {
  	u8 family;
  	union {
  		struct in_addr local_ip;
  #if IS_ENABLED(CONFIG_IPV6)
  		struct in6_addr local_ip6;
  #endif
  	};
  	union {
  		struct in_addr peer_ip;
  #if IS_ENABLED(CONFIG_IPV6)
  		struct in6_addr peer_ip6;
  #endif
  	};
  	__be16 local_udp_port;
  	__be16 peer_udp_port;
  	unsigned int use_udp_checksums:1, use_udp6_tx_checksums:1, use_udp6_rx_checksums:1, ipv6_v6only:1;
  };
  static inline int __maybe_unused __compat_udp_sock_create(struct net *net, struct __compat_udp_port_cfg *cfg, struct socket **sockp)
  {
  	struct udp_port_cfg old_cfg = {
  		.family = cfg->family,
  		.local_ip = cfg->local_ip,
  #if IS_ENABLED(CONFIG_IPV6)
  		.local_ip6 = cfg->local_ip6,
  #endif
  		.peer_ip = cfg->peer_ip,
  #if IS_ENABLED(CONFIG_IPV6)
  		.peer_ip6 = cfg->peer_ip6,
  #endif
  		.local_udp_port = cfg->local_udp_port,
  		.peer_udp_port = cfg->peer_udp_port,
  		.use_udp_checksums = cfg->use_udp_checksums,
  		.use_udp6_tx_checksums = cfg->use_udp6_tx_checksums,
  		.use_udp6_rx_checksums = cfg->use_udp6_rx_checksums
  	};
  	if (cfg->family == AF_INET)
  		return udp_sock_create4(net, &old_cfg, sockp);
  
  #if IS_ENABLED(CONFIG_IPV6)
  	if (cfg->family == AF_INET6) {
  		int ret;
  		int old_bindv6only;
  		struct net *nobns;
  
  		if (cfg->ipv6_v6only) {
  #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
  			nobns = &init_net;
  #else
  			nobns = net;
  #endif
  			/* Since udp_port_cfg only learned of ipv6_v6only in 4.3, we do this horrible
  			 * hack here and set the sysctl variable temporarily to something that will
  			 * set the right option for us in sock_create. It's super racey! */
  			old_bindv6only = nobns->ipv6.sysctl.bindv6only;
  			nobns->ipv6.sysctl.bindv6only = 1;
  		}
  		ret = udp_sock_create6(net, &old_cfg, sockp);
  		if (cfg->ipv6_v6only)
  			nobns->ipv6.sysctl.bindv6only = old_bindv6only;
  		return ret;
  	}
  #endif
  	return -EPFNOSUPPORT;
  }
  #define udp_port_cfg __compat_udp_port_cfg
  #define udp_sock_create(a, b, c) __compat_udp_sock_create(a, b, c)
  #endif
  