// SPDX-License-Identifier: GPL-2.0-or-later/* *	common UDP/RAW code *	Linux INET implementation * * Authors: * 	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> */ #include <linux/types.h>#include <linux/module.h>#include <linux/in.h>#include <net/ip.h>#include <net/sock.h>#include <net/route.h>#include <net/tcp_states.h>#include <net/sock_reuseport.h> int __ip4_datagram_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len){	struct inet_sock *inet = inet_sk(sk);	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;	struct flowi4 *fl4;	struct rtable *rt;	__be32 saddr;	int oif;	int err;  	if (addr_len < sizeof(*usin))		return -EINVAL; 	if (usin->sin_family != AF_INET)		return -EAFNOSUPPORT; 	sk_dst_reset(sk); 	oif = sk->sk_bound_dev_if;	saddr = inet->inet_saddr;	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {		if (!oif || netif_index_is_l3_master(sock_net(sk), oif))			oif = READ_ONCE(inet->mc_index);		if (!saddr)			saddr = READ_ONCE(inet->mc_addr);	} else if (!oif) {		oif = READ_ONCE(inet->uc_index);	}	fl4 = &inet->cork.fl.u.ip4;	rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr, oif,			      sk->sk_protocol, inet->inet_sport,			      usin->sin_port, sk);	if (IS_ERR(rt)) {		err = PTR_ERR(rt);		if (err == -ENETUNREACH)			IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);		goto out;	} 	if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {		ip_rt_put(rt);		err = -EACCES;		goto out;	} 	/* Update addresses before rehashing */	WRITE_ONCE(inet->inet_daddr, fl4->daddr);	inet->inet_dport = usin->sin_port;	if (!inet->inet_saddr)		inet->inet_saddr = fl4->saddr;	if (!inet->inet_rcv_saddr) {		WRITE_ONCE(inet->inet_rcv_saddr, fl4->saddr);		if (sk->sk_prot->rehash)			sk->sk_prot->rehash(sk);	}	reuseport_has_conns_set(sk);	sk->sk_state = TCP_ESTABLISHED;	sk_set_txhash(sk);	atomic_set(&inet->inet_id, get_random_u16()); 	sk_dst_set(sk, &rt->dst);	err = 0;out:	return err;}EXPORT_SYMBOL(__ip4_datagram_connect); int ip4_datagram_connect(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len){	int res; 	lock_sock(sk);	res = __ip4_datagram_connect(sk, uaddr, addr_len);	release_sock(sk);	return res;}EXPORT_SYMBOL(ip4_datagram_connect); /* Because UDP xmit path can manipulate sk_dst_cache without holding * socket lock, we need to use sk_dst_set() here, * even if we own the socket lock. */void ip4_datagram_release_cb(struct sock *sk){	const struct inet_sock *inet = inet_sk(sk);	struct dst_entry *dst;	struct flowi4 fl4;	struct rtable *rt; 	rcu_read_lock(); 	dst = __sk_dst_get(sk);	if (!dst || !READ_ONCE(dst->obsolete) || dst->ops->check(dst, 0)) {		rcu_read_unlock();		return;	} 	inet_sk_init_flowi4(inet, &fl4);	rt = ip_route_output_flow(sock_net(sk), &fl4, sk);	dst = !IS_ERR(rt) ? &rt->dst : NULL;	sk_dst_set(sk, dst); 	rcu_read_unlock();}EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);