1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * common UDP/RAW code
4 * Linux INET implementation
5 *
6 * Authors:
7 * Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
8 */
9
10#include <linux/types.h>
11#include <linux/module.h>
12#include <linux/in.h>
13#include <net/ip.h>
14#include <net/sock.h>
15#include <net/route.h>
16#include <net/tcp_states.h>
17#include <net/sock_reuseport.h>
18
19int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
20{
21 struct inet_sock *inet = inet_sk(sk);
22 struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
23 struct flowi4 *fl4;
24 struct rtable *rt;
25 __be32 saddr;
26 int oif;
27 int err;
28
29
30 if (addr_len < sizeof(*usin))
31 return -EINVAL;
32
33 if (usin->sin_family != AF_INET)
34 return -EAFNOSUPPORT;
35
36 sk_dst_reset(sk);
37
38 oif = sk->sk_bound_dev_if;
39 saddr = inet->inet_saddr;
40 if (ipv4_is_multicast(addr: usin->sin_addr.s_addr)) {
41 if (!oif || netif_index_is_l3_master(net: sock_net(sk), ifindex: oif))
42 oif = READ_ONCE(inet->mc_index);
43 if (!saddr)
44 saddr = READ_ONCE(inet->mc_addr);
45 } else if (!oif) {
46 oif = READ_ONCE(inet->uc_index);
47 }
48 fl4 = &inet->cork.fl.u.ip4;
49 rt = ip_route_connect(fl4, dst: usin->sin_addr.s_addr, src: saddr, oif,
50 protocol: sk->sk_protocol, sport: inet->inet_sport,
51 dport: usin->sin_port, sk);
52 if (IS_ERR(ptr: rt)) {
53 err = PTR_ERR(ptr: rt);
54 if (err == -ENETUNREACH)
55 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
56 goto out;
57 }
58
59 if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, flag: SOCK_BROADCAST)) {
60 ip_rt_put(rt);
61 err = -EACCES;
62 goto out;
63 }
64
65 /* Update addresses before rehashing */
66 inet->inet_daddr = fl4->daddr;
67 inet->inet_dport = usin->sin_port;
68 if (!inet->inet_saddr)
69 inet->inet_saddr = fl4->saddr;
70 if (!inet->inet_rcv_saddr) {
71 inet->inet_rcv_saddr = fl4->saddr;
72 if (sk->sk_prot->rehash)
73 sk->sk_prot->rehash(sk);
74 }
75 reuseport_has_conns_set(sk);
76 sk->sk_state = TCP_ESTABLISHED;
77 sk_set_txhash(sk);
78 atomic_set(v: &inet->inet_id, i: get_random_u16());
79
80 sk_dst_set(sk, dst: &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 struct dst_entry *dst;
106 struct flowi4 fl4;
107 struct rtable *rt;
108
109 rcu_read_lock();
110
111 dst = __sk_dst_get(sk);
112 if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
113 rcu_read_unlock();
114 return;
115 }
116
117 inet_sk_init_flowi4(inet, fl4: &fl4);
118 rt = ip_route_output_flow(sock_net(sk), flp: &fl4, sk);
119 dst = !IS_ERR(ptr: rt) ? &rt->dst : NULL;
120 sk_dst_set(sk, dst);
121
122 rcu_read_unlock();
123}
124EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);
125

source code of linux/net/ipv4/datagram.c