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         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         sk_set_txhash(sk);
  78         inet->inet_id = jiffies;
  79
  80         sk_dst_set(sk, &rt->dst);
  81         err = 0;
  82 out:
  83         return err;
  84 }
  85 EXPORT_SYMBOL(__ip4_datagram_connect);
  86
  87 int 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 }
  96 EXPORT_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  */
 102 void 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 }
 131 EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);