1/*
2 *	common UDP/RAW code
3 *	Linux INET implementation
4 *
5 * Authors:
6 * 	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
7 *
8 * 	This program is free software; you can redistribute it and/or
9 * 	modify it under the terms of the GNU General Public License
10 * 	as published by the Free Software Foundation; either version
11 * 	2 of the License, or (at your option) any later version.
12 */
13
14#include <linux/types.h>
15#include <linux/module.h>
16#include <linux/ip.h>
17#include <linux/in.h>
18#include <net/ip.h>
19#include <net/sock.h>
20#include <net/route.h>
21#include <net/tcp_states.h>
22
23int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
24{
25	struct inet_sock *inet = inet_sk(sk);
26	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
27	struct flowi4 *fl4;
28	struct rtable *rt;
29	__be32 saddr;
30	int oif;
31	int err;
32
33
34	if (addr_len < sizeof(*usin))
35		return -EINVAL;
36
37	if (usin->sin_family != AF_INET)
38		return -EAFNOSUPPORT;
39
40	sk_dst_reset(sk);
41
42	lock_sock(sk);
43
44	oif = sk->sk_bound_dev_if;
45	saddr = inet->inet_saddr;
46	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
47		if (!oif)
48			oif = inet->mc_index;
49		if (!saddr)
50			saddr = inet->mc_addr;
51	}
52	fl4 = &inet->cork.fl.u.ip4;
53	rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
54			      RT_CONN_FLAGS(sk), oif,
55			      sk->sk_protocol,
56			      inet->inet_sport, usin->sin_port, sk);
57	if (IS_ERR(rt)) {
58		err = PTR_ERR(rt);
59		if (err == -ENETUNREACH)
60			IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
61		goto out;
62	}
63
64	if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
65		ip_rt_put(rt);
66		err = -EACCES;
67		goto out;
68	}
69	if (!inet->inet_saddr)
70		inet->inet_saddr = fl4->saddr;	/* Update source address */
71	if (!inet->inet_rcv_saddr) {
72		inet->inet_rcv_saddr = fl4->saddr;
73		if (sk->sk_prot->rehash)
74			sk->sk_prot->rehash(sk);
75	}
76	inet->inet_daddr = fl4->daddr;
77	inet->inet_dport = usin->sin_port;
78	sk->sk_state = TCP_ESTABLISHED;
79	inet_set_txhash(sk);
80	inet->inet_id = jiffies;
81
82	sk_dst_set(sk, &rt->dst);
83	err = 0;
84out:
85	release_sock(sk);
86	return err;
87}
88EXPORT_SYMBOL(ip4_datagram_connect);
89
90/* Because UDP xmit path can manipulate sk_dst_cache without holding
91 * socket lock, we need to use sk_dst_set() here,
92 * even if we own the socket lock.
93 */
94void ip4_datagram_release_cb(struct sock *sk)
95{
96	const struct inet_sock *inet = inet_sk(sk);
97	const struct ip_options_rcu *inet_opt;
98	__be32 daddr = inet->inet_daddr;
99	struct dst_entry *dst;
100	struct flowi4 fl4;
101	struct rtable *rt;
102
103	rcu_read_lock();
104
105	dst = __sk_dst_get(sk);
106	if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
107		rcu_read_unlock();
108		return;
109	}
110	inet_opt = rcu_dereference(inet->inet_opt);
111	if (inet_opt && inet_opt->opt.srr)
112		daddr = inet_opt->opt.faddr;
113	rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
114				   inet->inet_saddr, inet->inet_dport,
115				   inet->inet_sport, sk->sk_protocol,
116				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
117
118	dst = !IS_ERR(rt) ? &rt->dst : NULL;
119	sk_dst_set(sk, dst);
120
121	rcu_read_unlock();
122}
123EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
124