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	oif = sk->sk_bound_dev_if;
43	saddr = inet->inet_saddr;
44	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {
45		if (!oif)
46			oif = inet->mc_index;
47		if (!saddr)
48			saddr = inet->mc_addr;
49	}
50	fl4 = &inet->cork.fl.u.ip4;
51	rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,
52			      RT_CONN_FLAGS(sk), oif,
53			      sk->sk_protocol,
54			      inet->inet_sport, usin->sin_port, sk);
55	if (IS_ERR(rt)) {
56		err = PTR_ERR(rt);
57		if (err == -ENETUNREACH)
58			IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
59		goto out;
60	}
61
62	if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
63		ip_rt_put(rt);
64		err = -EACCES;
65		goto out;
66	}
67	if (!inet->inet_saddr)
68		inet->inet_saddr = fl4->saddr;	/* Update source address */
69	if (!inet->inet_rcv_saddr) {
70		inet->inet_rcv_saddr = fl4->saddr;
71		if (sk->sk_prot->rehash)
72			sk->sk_prot->rehash(sk);
73	}
74	inet->inet_daddr = fl4->daddr;
75	inet->inet_dport = usin->sin_port;
76	sk->sk_state = TCP_ESTABLISHED;
77	inet_set_txhash(sk);
78	inet->inet_id = jiffies;
79
80	sk_dst_set(sk, &rt->dst);
81	err = 0;
82out:
83	return err;
84}
85EXPORT_SYMBOL(__ip4_datagram_connect);
86
87int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
88{
89	int res;
90
91	lock_sock(sk);
92	res = __ip4_datagram_connect(sk, uaddr, addr_len);
93	release_sock(sk);
94	return res;
95}
96EXPORT_SYMBOL(ip4_datagram_connect);
97
98/* Because UDP xmit path can manipulate sk_dst_cache without holding
99 * socket lock, we need to use sk_dst_set() here,
100 * even if we own the socket lock.
101 */
102void ip4_datagram_release_cb(struct sock *sk)
103{
104	const struct inet_sock *inet = inet_sk(sk);
105	const struct ip_options_rcu *inet_opt;
106	__be32 daddr = inet->inet_daddr;
107	struct dst_entry *dst;
108	struct flowi4 fl4;
109	struct rtable *rt;
110
111	rcu_read_lock();
112
113	dst = __sk_dst_get(sk);
114	if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
115		rcu_read_unlock();
116		return;
117	}
118	inet_opt = rcu_dereference(inet->inet_opt);
119	if (inet_opt && inet_opt->opt.srr)
120		daddr = inet_opt->opt.faddr;
121	rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
122				   inet->inet_saddr, inet->inet_dport,
123				   inet->inet_sport, sk->sk_protocol,
124				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
125
126	dst = !IS_ERR(rt) ? &rt->dst : NULL;
127	sk_dst_set(sk, dst);
128
129	rcu_read_unlock();
130}
131EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
132