/* net/tipc/udp_media.c: IP bearer support for TIPC
   *
   * Copyright (c) 2015, Ericsson AB
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <linux/socket.h>
  #include <linux/ip.h>
  #include <linux/udp.h>
  #include <linux/inet.h>
  #include <linux/inetdevice.h>
  #include <linux/igmp.h>
  #include <linux/kernel.h>
  #include <linux/workqueue.h>
  #include <linux/list.h>
  #include <net/sock.h>
  #include <net/ip.h>
  #include <net/udp_tunnel.h>

  #include <net/ipv6_stubs.h>

  #include <linux/tipc_netlink.h>
  #include "core.h"

  #include "addr.h"
  #include "net.h"

  #include "bearer.h"

  #include "netlink.h"

  #include "msg.h"

  #include "udp_media.h"

  
  /* IANA assigned UDP port */
  #define UDP_PORT_DEFAULT	6118

  #define UDP_MIN_HEADROOM        48

  /**
   * struct udp_media_addr - IP/UDP addressing information
   *
   * This is the bearer level originating address used in neighbor discovery
   * messages, and all fields should be in network byte order
   */
  struct udp_media_addr {
  	__be16	proto;

  	__be16	port;

  	union {
  		struct in_addr ipv4;
  		struct in6_addr ipv6;
  	};
  };

  /* struct udp_replicast - container for UDP remote addresses */
  struct udp_replicast {
  	struct udp_media_addr addr;

  	struct dst_cache dst_cache;

  	struct rcu_head rcu;
  	struct list_head list;
  };

  /**
   * struct udp_bearer - ip/udp bearer data structure
   * @bearer:	associated generic tipc bearer
   * @ubsock:	bearer associated socket
   * @ifindex:	local address scope
   * @work:	used to schedule deferred work on a bearer
   */
  struct udp_bearer {
  	struct tipc_bearer __rcu *bearer;
  	struct socket *ubsock;
  	u32 ifindex;
  	struct work_struct work;

  	struct udp_replicast rcast;

  };

  static int tipc_udp_is_mcast_addr(struct udp_media_addr *addr)
  {
  	if (ntohs(addr->proto) == ETH_P_IP)
  		return ipv4_is_multicast(addr->ipv4.s_addr);
  #if IS_ENABLED(CONFIG_IPV6)
  	else
  		return ipv6_addr_is_multicast(&addr->ipv6);
  #endif
  	return 0;
  }

  /* udp_media_addr_set - convert a ip/udp address to a TIPC media address */
  static void tipc_udp_media_addr_set(struct tipc_media_addr *addr,
  				    struct udp_media_addr *ua)
  {
  	memset(addr, 0, sizeof(struct tipc_media_addr));
  	addr->media_id = TIPC_MEDIA_TYPE_UDP;
  	memcpy(addr->value, ua, sizeof(struct udp_media_addr));

  
  	if (tipc_udp_is_mcast_addr(ua))

  		addr->broadcast = TIPC_BROADCAST_SUPPORT;

  }
  
  /* tipc_udp_addr2str - convert ip/udp address to string */
  static int tipc_udp_addr2str(struct tipc_media_addr *a, char *buf, int size)
  {
  	struct udp_media_addr *ua = (struct udp_media_addr *)&a->value;
  
  	if (ntohs(ua->proto) == ETH_P_IP)

  		snprintf(buf, size, "%pI4:%u", &ua->ipv4, ntohs(ua->port));

  	else if (ntohs(ua->proto) == ETH_P_IPV6)

  		snprintf(buf, size, "%pI6:%u", &ua->ipv6, ntohs(ua->port));

  	else
  		pr_err("Invalid UDP media address
  ");
  	return 0;
  }
  
  /* tipc_udp_msg2addr - extract an ip/udp address from a TIPC ndisc message */
  static int tipc_udp_msg2addr(struct tipc_bearer *b, struct tipc_media_addr *a,
  			     char *msg)
  {
  	struct udp_media_addr *ua;
  
  	ua = (struct udp_media_addr *) (msg + TIPC_MEDIA_ADDR_OFFSET);
  	if (msg[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_UDP)
  		return -EINVAL;
  	tipc_udp_media_addr_set(a, ua);
  	return 0;
  }
  
  /* tipc_udp_addr2msg - write an ip/udp address to a TIPC ndisc message */
  static int tipc_udp_addr2msg(char *msg, struct tipc_media_addr *a)
  {
  	memset(msg, 0, TIPC_MEDIA_INFO_SIZE);
  	msg[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_UDP;
  	memcpy(msg + TIPC_MEDIA_ADDR_OFFSET, a->value,
  	       sizeof(struct udp_media_addr));
  	return 0;
  }
  
  /* tipc_send_msg - enqueue a send request */

  static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
  			 struct udp_bearer *ub, struct udp_media_addr *src,

  			 struct udp_media_addr *dst, struct dst_cache *cache)

  {

  	struct dst_entry *ndst;

  	int ttl, err = 0;

  	local_bh_disable();
  	ndst = dst_cache_get(cache);

  	if (dst->proto == htons(ETH_P_IP)) {

  		struct rtable *rt = (struct rtable *)ndst;
  
  		if (!rt) {
  			struct flowi4 fl = {
  				.daddr = dst->ipv4.s_addr,
  				.saddr = src->ipv4.s_addr,
  				.flowi4_mark = skb->mark,
  				.flowi4_proto = IPPROTO_UDP
  			};
  			rt = ip_route_output_key(net, &fl);
  			if (IS_ERR(rt)) {
  				err = PTR_ERR(rt);
  				goto tx_error;
  			}
  			dst_cache_set_ip4(cache, &rt->dst, fl.saddr);

  		}

  		ttl = ip4_dst_hoplimit(&rt->dst);

  		udp_tunnel_xmit_skb(rt, ub->ubsock->sk, skb, src->ipv4.s_addr,

  				    dst->ipv4.s_addr, 0, ttl, 0, src->port,
  				    dst->port, false, true);

  #if IS_ENABLED(CONFIG_IPV6)
  	} else {

  		if (!ndst) {
  			struct flowi6 fl6 = {
  				.flowi6_oif = ub->ifindex,
  				.daddr = dst->ipv6,
  				.saddr = src->ipv6,
  				.flowi6_proto = IPPROTO_UDP
  			};

  			ndst = ipv6_stub->ipv6_dst_lookup_flow(net,
  							       ub->ubsock->sk,
  							       &fl6, NULL);
  			if (IS_ERR(ndst)) {
  				err = PTR_ERR(ndst);

  				goto tx_error;

  			}

  			dst_cache_set_ip6(cache, ndst, &fl6.saddr);
  		}

  		ttl = ip6_dst_hoplimit(ndst);

  		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
  					   &src->ipv6, &dst->ipv6, 0, ttl, 0,
  					   src->port, dst->port, false);

  #endif
  	}

  	local_bh_enable();

  	return err;
  
  tx_error:

  	local_bh_enable();

  	kfree_skb(skb);

  	return err;
  }

  static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
  			     struct tipc_bearer *b,
  			     struct tipc_media_addr *addr)
  {
  	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
  	struct udp_media_addr *dst = (struct udp_media_addr *)&addr->value;

  	struct udp_replicast *rcast;

  	struct udp_bearer *ub;
  	int err = 0;
  
  	if (skb_headroom(skb) < UDP_MIN_HEADROOM) {
  		err = pskb_expand_head(skb, UDP_MIN_HEADROOM, 0, GFP_ATOMIC);
  		if (err)

  			goto out;

  	}
  
  	skb_set_inner_protocol(skb, htons(ETH_P_TIPC));

  	ub = rcu_dereference(b->media_ptr);

  	if (!ub) {
  		err = -ENODEV;

  		goto out;

  	}

  	if (addr->broadcast != TIPC_REPLICAST_SUPPORT)

  		return tipc_udp_xmit(net, skb, ub, src, dst,
  				     &ub->rcast.dst_cache);

  	/* Replicast, send an skb to each configured IP address */
  	list_for_each_entry_rcu(rcast, &ub->rcast.list, list) {
  		struct sk_buff *_skb;
  
  		_skb = pskb_copy(skb, GFP_ATOMIC);
  		if (!_skb) {
  			err = -ENOMEM;
  			goto out;
  		}

  		err = tipc_udp_xmit(net, _skb, ub, src, &rcast->addr,
  				    &rcast->dst_cache);

  		if (err)

  			goto out;

  	}
  	err = 0;
  out:

  	kfree_skb(skb);
  	return err;
  }

  static bool tipc_udp_is_known_peer(struct tipc_bearer *b,
  				   struct udp_media_addr *addr)
  {
  	struct udp_replicast *rcast, *tmp;
  	struct udp_bearer *ub;
  
  	ub = rcu_dereference_rtnl(b->media_ptr);
  	if (!ub) {
  		pr_err_ratelimited("UDP bearer instance not found
  ");
  		return false;
  	}
  
  	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
  		if (!memcmp(&rcast->addr, addr, sizeof(struct udp_media_addr)))
  			return true;
  	}
  
  	return false;
  }

  static int tipc_udp_rcast_add(struct tipc_bearer *b,
  			      struct udp_media_addr *addr)
  {
  	struct udp_replicast *rcast;
  	struct udp_bearer *ub;
  
  	ub = rcu_dereference_rtnl(b->media_ptr);
  	if (!ub)
  		return -ENODEV;
  
  	rcast = kmalloc(sizeof(*rcast), GFP_ATOMIC);
  	if (!rcast)
  		return -ENOMEM;

  	if (dst_cache_init(&rcast->dst_cache, GFP_ATOMIC)) {
  		kfree(rcast);
  		return -ENOMEM;
  	}

  	memcpy(&rcast->addr, addr, sizeof(struct udp_media_addr));
  
  	if (ntohs(addr->proto) == ETH_P_IP)
  		pr_info("New replicast peer: %pI4
  ", &rcast->addr.ipv4);
  #if IS_ENABLED(CONFIG_IPV6)
  	else if (ntohs(addr->proto) == ETH_P_IPV6)
  		pr_info("New replicast peer: %pI6
  ", &rcast->addr.ipv6);
  #endif

  	b->bcast_addr.broadcast = TIPC_REPLICAST_SUPPORT;

  	list_add_rcu(&rcast->list, &ub->rcast.list);
  	return 0;
  }

  static int tipc_udp_rcast_disc(struct tipc_bearer *b, struct sk_buff *skb)
  {
  	struct udp_media_addr src = {0};
  	struct udp_media_addr *dst;
  
  	dst = (struct udp_media_addr *)&b->bcast_addr.value;
  	if (tipc_udp_is_mcast_addr(dst))
  		return 0;
  
  	src.port = udp_hdr(skb)->source;
  
  	if (ip_hdr(skb)->version == 4) {
  		struct iphdr *iphdr = ip_hdr(skb);
  
  		src.proto = htons(ETH_P_IP);
  		src.ipv4.s_addr = iphdr->saddr;
  		if (ipv4_is_multicast(iphdr->daddr))
  			return 0;
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (ip_hdr(skb)->version == 6) {
  		struct ipv6hdr *iphdr = ipv6_hdr(skb);
  
  		src.proto = htons(ETH_P_IPV6);
  		src.ipv6 = iphdr->saddr;
  		if (ipv6_addr_is_multicast(&iphdr->daddr))
  			return 0;
  #endif
  	} else {
  		return 0;
  	}
  
  	if (likely(tipc_udp_is_known_peer(b, &src)))
  		return 0;
  
  	return tipc_udp_rcast_add(b, &src);
  }

  /* tipc_udp_recv - read data from bearer socket */
  static int tipc_udp_recv(struct sock *sk, struct sk_buff *skb)
  {
  	struct udp_bearer *ub;
  	struct tipc_bearer *b;

  	struct tipc_msg *hdr;
  	int err;

  
  	ub = rcu_dereference_sk_user_data(sk);
  	if (!ub) {
  		pr_err_ratelimited("Failed to get UDP bearer reference");

  		goto out;

  	}

  	skb_pull(skb, sizeof(struct udphdr));

  	hdr = buf_msg(skb);

  	b = rcu_dereference(ub->bearer);

  	if (!b)

  		goto out;

  	if (b && test_bit(0, &b->up)) {

  		TIPC_SKB_CB(skb)->flags = 0;

  		tipc_rcv(sock_net(sk), skb, b);

  		return 0;
  	}

  
  	if (unlikely(msg_user(hdr) == LINK_CONFIG)) {
  		err = tipc_udp_rcast_disc(b, skb);
  		if (err)

  			goto out;

  	}

  out:

  	kfree_skb(skb);
  	return 0;
  }
  
  static int enable_mcast(struct udp_bearer *ub, struct udp_media_addr *remote)
  {
  	int err = 0;
  	struct ip_mreqn mreqn;
  	struct sock *sk = ub->ubsock->sk;
  
  	if (ntohs(remote->proto) == ETH_P_IP) {

  		mreqn.imr_multiaddr = remote->ipv4;
  		mreqn.imr_ifindex = ub->ifindex;

  		err = ip_mc_join_group(sk, &mreqn);

  #if IS_ENABLED(CONFIG_IPV6)

  	} else {

  		err = ipv6_stub->ipv6_sock_mc_join(sk, ub->ifindex,
  						   &remote->ipv6);
  #endif

  	}
  	return err;
  }

  static int __tipc_nl_add_udp_addr(struct sk_buff *skb,
  				  struct udp_media_addr *addr, int nla_t)
  {
  	if (ntohs(addr->proto) == ETH_P_IP) {
  		struct sockaddr_in ip4;

  		memset(&ip4, 0, sizeof(ip4));

  		ip4.sin_family = AF_INET;
  		ip4.sin_port = addr->port;
  		ip4.sin_addr.s_addr = addr->ipv4.s_addr;
  		if (nla_put(skb, nla_t, sizeof(ip4), &ip4))
  			return -EMSGSIZE;
  
  #if IS_ENABLED(CONFIG_IPV6)
  	} else if (ntohs(addr->proto) == ETH_P_IPV6) {
  		struct sockaddr_in6 ip6;

  		memset(&ip6, 0, sizeof(ip6));

  		ip6.sin6_family = AF_INET6;
  		ip6.sin6_port  = addr->port;
  		memcpy(&ip6.sin6_addr, &addr->ipv6, sizeof(struct in6_addr));
  		if (nla_put(skb, nla_t, sizeof(ip6), &ip6))
  			return -EMSGSIZE;
  #endif
  	}
  
  	return 0;
  }

  int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb)
  {
  	u32 bid = cb->args[0];
  	u32 skip_cnt = cb->args[1];
  	u32 portid = NETLINK_CB(cb->skb).portid;
  	struct udp_replicast *rcast, *tmp;
  	struct tipc_bearer *b;
  	struct udp_bearer *ub;
  	void *hdr;
  	int err;
  	int i;
  
  	if (!bid && !skip_cnt) {

  		struct nlattr **attrs = genl_dumpit_info(cb)->attrs;

  		struct net *net = sock_net(skb->sk);
  		struct nlattr *battrs[TIPC_NLA_BEARER_MAX + 1];

  		char *bname;

  		if (!attrs[TIPC_NLA_BEARER])
  			return -EINVAL;

  		err = nla_parse_nested_deprecated(battrs, TIPC_NLA_BEARER_MAX,
  						  attrs[TIPC_NLA_BEARER],
  						  tipc_nl_bearer_policy, NULL);

  		if (err)
  			return err;
  
  		if (!battrs[TIPC_NLA_BEARER_NAME])
  			return -EINVAL;
  
  		bname = nla_data(battrs[TIPC_NLA_BEARER_NAME]);
  
  		rtnl_lock();
  		b = tipc_bearer_find(net, bname);
  		if (!b) {
  			rtnl_unlock();
  			return -EINVAL;
  		}
  		bid = b->identity;
  	} else {
  		struct net *net = sock_net(skb->sk);
  		struct tipc_net *tn = net_generic(net, tipc_net_id);
  
  		rtnl_lock();
  		b = rtnl_dereference(tn->bearer_list[bid]);
  		if (!b) {
  			rtnl_unlock();
  			return -EINVAL;
  		}
  	}

  	ub = rtnl_dereference(b->media_ptr);

  	if (!ub) {
  		rtnl_unlock();
  		return -EINVAL;
  	}
  
  	i = 0;
  	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
  		if (i < skip_cnt)
  			goto count;
  
  		hdr = genlmsg_put(skb, portid, cb->nlh->nlmsg_seq,
  				  &tipc_genl_family, NLM_F_MULTI,
  				  TIPC_NL_BEARER_GET);
  		if (!hdr)
  			goto done;
  
  		err = __tipc_nl_add_udp_addr(skb, &rcast->addr,
  					     TIPC_NLA_UDP_REMOTE);
  		if (err) {
  			genlmsg_cancel(skb, hdr);
  			goto done;
  		}
  		genlmsg_end(skb, hdr);
  count:
  		i++;
  	}
  done:
  	rtnl_unlock();
  	cb->args[0] = bid;
  	cb->args[1] = i;
  
  	return skb->len;
  }

  int tipc_udp_nl_add_bearer_data(struct tipc_nl_msg *msg, struct tipc_bearer *b)
  {
  	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;
  	struct udp_media_addr *dst;
  	struct udp_bearer *ub;
  	struct nlattr *nest;

  	ub = rtnl_dereference(b->media_ptr);

  	if (!ub)
  		return -ENODEV;

  	nest = nla_nest_start_noflag(msg->skb, TIPC_NLA_BEARER_UDP_OPTS);

  	if (!nest)
  		goto msg_full;
  
  	if (__tipc_nl_add_udp_addr(msg->skb, src, TIPC_NLA_UDP_LOCAL))
  		goto msg_full;
  
  	dst = (struct udp_media_addr *)&b->bcast_addr.value;
  	if (__tipc_nl_add_udp_addr(msg->skb, dst, TIPC_NLA_UDP_REMOTE))
  		goto msg_full;
  
  	if (!list_empty(&ub->rcast.list)) {
  		if (nla_put_flag(msg->skb, TIPC_NLA_UDP_MULTI_REMOTEIP))
  			goto msg_full;
  	}
  
  	nla_nest_end(msg->skb, nest);
  	return 0;
  msg_full:
  	nla_nest_cancel(msg->skb, nest);
  	return -EMSGSIZE;
  }

  /**

   * tipc_parse_udp_addr - build udp media address from netlink data

   * @nla:	netlink attribute containing sockaddr storage aligned address

   * @addr:	tipc media address to fill with address, port and protocol type
   * @scope_id:	IPv6 scope id pointer, not NULL indicates it's required

   */

  
  static int tipc_parse_udp_addr(struct nlattr *nla, struct udp_media_addr *addr,
  			       u32 *scope_id)

  {

  	struct sockaddr_storage sa;

  	nla_memcpy(&sa, nla, sizeof(sa));
  	if (sa.ss_family == AF_INET) {
  		struct sockaddr_in *ip4 = (struct sockaddr_in *)&sa;
  
  		addr->proto = htons(ETH_P_IP);
  		addr->port = ip4->sin_port;
  		addr->ipv4.s_addr = ip4->sin_addr.s_addr;

  		return 0;
  
  #if IS_ENABLED(CONFIG_IPV6)

  	} else if (sa.ss_family == AF_INET6) {
  		struct sockaddr_in6 *ip6 = (struct sockaddr_in6 *)&sa;
  
  		addr->proto = htons(ETH_P_IPV6);
  		addr->port = ip6->sin6_port;
  		memcpy(&addr->ipv6, &ip6->sin6_addr, sizeof(struct in6_addr));
  
  		/* Scope ID is only interesting for local addresses */
  		if (scope_id) {
  			int atype;
  
  			atype = ipv6_addr_type(&ip6->sin6_addr);
  			if (__ipv6_addr_needs_scope_id(atype) &&
  			    !ip6->sin6_scope_id) {
  				return -EINVAL;
  			}
  
  			*scope_id = ip6->sin6_scope_id ? : 0;
  		}

  		return 0;
  #endif
  	}
  	return -EADDRNOTAVAIL;
  }

  int tipc_udp_nl_bearer_add(struct tipc_bearer *b, struct nlattr *attr)
  {
  	int err;
  	struct udp_media_addr addr = {0};
  	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];
  	struct udp_media_addr *dst;

  	if (nla_parse_nested_deprecated(opts, TIPC_NLA_UDP_MAX, attr, tipc_nl_udp_policy, NULL))

  		return -EINVAL;
  
  	if (!opts[TIPC_NLA_UDP_REMOTE])
  		return -EINVAL;
  
  	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_REMOTE], &addr, NULL);
  	if (err)
  		return err;
  
  	dst = (struct udp_media_addr *)&b->bcast_addr.value;
  	if (tipc_udp_is_mcast_addr(dst)) {
  		pr_err("Can't add remote ip to TIPC UDP multicast bearer
  ");
  		return -EINVAL;
  	}

  	if (tipc_udp_is_known_peer(b, &addr))
  		return 0;

  	return tipc_udp_rcast_add(b, &addr);
  }

  /**
   * tipc_udp_enable - callback to create a new udp bearer instance
   * @net:	network namespace
   * @b:		pointer to generic tipc_bearer
   * @attrs:	netlink bearer configuration
   *
   * validate the bearer parameters and initialize the udp bearer
   * rtnl_lock should be held
   */
  static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
  			   struct nlattr *attrs[])
  {
  	int err = -EINVAL;
  	struct udp_bearer *ub;

  	struct udp_media_addr remote = {0};

  	struct udp_media_addr local = {0};
  	struct udp_port_cfg udp_conf = {0};

  	struct udp_tunnel_sock_cfg tuncfg = {NULL};

  	struct nlattr *opts[TIPC_NLA_UDP_MAX + 1];

  	u8 node_id[NODE_ID_LEN] = {0,};

  	struct net_device *dev;

  	int rmcast = 0;

  
  	ub = kzalloc(sizeof(*ub), GFP_ATOMIC);
  	if (!ub)
  		return -ENOMEM;

  	INIT_LIST_HEAD(&ub->rcast.list);

  	if (!attrs[TIPC_NLA_BEARER_UDP_OPTS])
  		goto err;

  	if (nla_parse_nested_deprecated(opts, TIPC_NLA_UDP_MAX, attrs[TIPC_NLA_BEARER_UDP_OPTS], tipc_nl_udp_policy, NULL))

  		goto err;
  
  	if (!opts[TIPC_NLA_UDP_LOCAL] || !opts[TIPC_NLA_UDP_REMOTE]) {
  		pr_err("Invalid UDP bearer configuration");

  		err = -EINVAL;
  		goto err;

  	}
  
  	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_LOCAL], &local,
  				  &ub->ifindex);
  	if (err)
  		goto err;

  	err = tipc_parse_udp_addr(opts[TIPC_NLA_UDP_REMOTE], &remote, NULL);

  	if (err)
  		goto err;

  	if (remote.proto != local.proto) {
  		err = -EINVAL;
  		goto err;
  	}

  	/* Checking remote ip address */
  	rmcast = tipc_udp_is_mcast_addr(&remote);

  	/* Autoconfigure own node identity if needed */
  	if (!tipc_own_id(net)) {
  		memcpy(node_id, local.ipv6.in6_u.u6_addr8, 16);
  		tipc_net_init(net, node_id, 0);
  	}
  	if (!tipc_own_id(net)) {
  		pr_warn("Failed to set node id, please configure manually
  ");

  		err = -EINVAL;
  		goto err;

  	}

  	b->bcast_addr.media_id = TIPC_MEDIA_TYPE_UDP;

  	b->bcast_addr.broadcast = TIPC_BROADCAST_SUPPORT;

  	rcu_assign_pointer(b->media_ptr, ub);
  	rcu_assign_pointer(ub->bearer, b);
  	tipc_udp_media_addr_set(&b->addr, &local);

  	if (local.proto == htons(ETH_P_IP)) {

  		dev = __ip_dev_find(net, local.ipv4.s_addr, false);
  		if (!dev) {
  			err = -ENODEV;
  			goto err;
  		}
  		udp_conf.family = AF_INET;

  
  		/* Switch to use ANY to receive packets from group */
  		if (rmcast)
  			udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
  		else
  			udp_conf.local_ip.s_addr = local.ipv4.s_addr;

  		udp_conf.use_udp_checksums = false;
  		ub->ifindex = dev->ifindex;

  		if (tipc_mtu_bad(dev, sizeof(struct iphdr) +
  				      sizeof(struct udphdr))) {
  			err = -EINVAL;
  			goto err;
  		}

  		b->mtu = b->media->mtu;

  #if IS_ENABLED(CONFIG_IPV6)

  	} else if (local.proto == htons(ETH_P_IPV6)) {

  		dev = ub->ifindex ? __dev_get_by_index(net, ub->ifindex) : NULL;
  		dev = ipv6_dev_find(net, &local.ipv6, dev);

  		if (!dev) {
  			err = -ENODEV;
  			goto err;
  		}

  		udp_conf.family = AF_INET6;
  		udp_conf.use_udp6_tx_checksums = true;
  		udp_conf.use_udp6_rx_checksums = true;

  		if (rmcast)
  			udp_conf.local_ip6 = in6addr_any;
  		else
  			udp_conf.local_ip6 = local.ipv6;

  		ub->ifindex = dev->ifindex;

  		b->mtu = 1280;
  #endif
  	} else {
  		err = -EAFNOSUPPORT;
  		goto err;
  	}

  	udp_conf.local_udp_port = local.port;

  	err = udp_sock_create(net, &udp_conf, &ub->ubsock);
  	if (err)
  		goto err;
  	tuncfg.sk_user_data = ub;
  	tuncfg.encap_type = 1;
  	tuncfg.encap_rcv = tipc_udp_recv;
  	tuncfg.encap_destroy = NULL;
  	setup_udp_tunnel_sock(net, ub->ubsock, &tuncfg);

  	err = dst_cache_init(&ub->rcast.dst_cache, GFP_ATOMIC);
  	if (err)

  		goto free;

  	/**
  	 * The bcast media address port is used for all peers and the ip
  	 * is used if it's a multicast address.
  	 */
  	memcpy(&b->bcast_addr.value, &remote, sizeof(remote));

  	if (rmcast)

  		err = enable_mcast(ub, &remote);
  	else
  		err = tipc_udp_rcast_add(b, &remote);
  	if (err)

  		goto free;

  	return 0;

  
  free:

  	dst_cache_destroy(&ub->rcast.dst_cache);

  	udp_tunnel_sock_release(ub->ubsock);
  err:

  	kfree(ub);
  	return err;
  }
  
  /* cleanup_bearer - break the socket/bearer association */
  static void cleanup_bearer(struct work_struct *work)
  {
  	struct udp_bearer *ub = container_of(work, struct udp_bearer, work);

  	struct udp_replicast *rcast, *tmp;
  
  	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {

  		dst_cache_destroy(&rcast->dst_cache);

  		list_del_rcu(&rcast->list);
  		kfree_rcu(rcast, rcu);
  	}

  	dst_cache_destroy(&ub->rcast.dst_cache);

  	udp_tunnel_sock_release(ub->ubsock);

  	synchronize_net();
  	kfree(ub);
  }
  
  /* tipc_udp_disable - detach bearer from socket */
  static void tipc_udp_disable(struct tipc_bearer *b)
  {
  	struct udp_bearer *ub;

  	ub = rtnl_dereference(b->media_ptr);

  	if (!ub) {
  		pr_err("UDP bearer instance not found
  ");
  		return;
  	}

  	sock_set_flag(ub->ubsock->sk, SOCK_DEAD);

  	RCU_INIT_POINTER(ub->bearer, NULL);
  
  	/* sock_release need to be done outside of rtnl lock */
  	INIT_WORK(&ub->work, cleanup_bearer);
  	schedule_work(&ub->work);
  }
  
  struct tipc_media udp_media_info = {
  	.send_msg	= tipc_udp_send_msg,
  	.enable_media	= tipc_udp_enable,
  	.disable_media	= tipc_udp_disable,
  	.addr2str	= tipc_udp_addr2str,
  	.addr2msg	= tipc_udp_addr2msg,
  	.msg2addr	= tipc_udp_msg2addr,
  	.priority	= TIPC_DEF_LINK_PRI,
  	.tolerance	= TIPC_DEF_LINK_TOL,

  	.min_win	= TIPC_DEF_LINK_WIN,
  	.max_win	= TIPC_DEF_LINK_WIN,

  	.mtu		= TIPC_DEF_LINK_UDP_MTU,

  	.type_id	= TIPC_MEDIA_TYPE_UDP,
  	.hwaddr_len	= 0,
  	.name		= "udp"
  };