net/ipv4/datagram.c

   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
  23 int 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, true);
  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->inet_id = jiffies;
  80
  81         sk_dst_set(sk, &rt->dst);
  82         err = 0;
  83 out:
  84         release_sock(sk);
  85         return err;
  86 }
  87 EXPORT_SYMBOL(ip4_datagram_connect);
  88
  89 /* Because UDP xmit path can manipulate sk_dst_cache without holding
  90  * socket lock, we need to use sk_dst_set() here,
  91  * even if we own the socket lock.
  92  */
  93 void ip4_datagram_release_cb(struct sock *sk)
  94 {
  95         const struct inet_sock *inet = inet_sk(sk);
  96         const struct ip_options_rcu *inet_opt;
  97         __be32 daddr = inet->inet_daddr;
  98         struct dst_entry *dst;
  99         struct flowi4 fl4;
 100         struct rtable *rt;
 101
 102         rcu_read_lock();
 103
 104         dst = __sk_dst_get(sk);
 105         if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
 106                 rcu_read_unlock();
 107                 return;
 108         }
 109         inet_opt = rcu_dereference(inet->inet_opt);
 110         if (inet_opt && inet_opt->opt.srr)
 111                 daddr = inet_opt->opt.faddr;
 112         rt = ip_route_output_ports(sock_net(sk), &fl4, sk, daddr,
 113                                    inet->inet_saddr, inet->inet_dport,
 114                                    inet->inet_sport, sk->sk_protocol,
 115                                    RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
 116
 117         dst = !IS_ERR(rt) ? &rt->dst : NULL;
 118         sk_dst_set(sk, dst);
 119
 120         rcu_read_unlock();
 121 }
 122 EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);