Linux Kernel TCP socket functions

Question

So I have been looking through the Linux Kernel v3.8.0-19-generic source code and I noticed that the proto struct, whose members are virtual functions for socket operations depending on the particular protocol used and the proto struct for tcp, called tcp_prot looks like this:

struct proto tcp_prot = {
    .name           = "TCP",
    .owner          = THIS_MODULE,
    .close          = tcp_close,
    .connect        = tcp_v4_connect,
    .disconnect     = tcp_disconnect,
    .accept         = inet_csk_accept,
    .ioctl          = tcp_ioctl,
    .init           = tcp_v4_init_sock,
    .destroy        = tcp_v4_destroy_sock,
    .shutdown       = tcp_shutdown,
    .setsockopt     = tcp_setsockopt,
    .getsockopt     = tcp_getsockopt,
    .recvmsg        = tcp_recvmsg,
    .sendmsg        = tcp_sendmsg,
    .sendpage       = tcp_sendpage,
    .backlog_rcv        = tcp_v4_do_rcv,
    .release_cb     = tcp_release_cb,
    .mtu_reduced        = tcp_v4_mtu_reduced,
    .hash           = inet_hash,
    .unhash         = inet_unhash,
    .get_port       = inet_csk_get_port,
    .enter_memory_pressure  = tcp_enter_memory_pressure,
    .sockets_allocated  = &tcp_sockets_allocated,
    .orphan_count       = &tcp_orphan_count,
    .memory_allocated   = &tcp_memory_allocated,
    .memory_pressure    = &tcp_memory_pressure,
    .sysctl_wmem        = sysctl_tcp_wmem,
    .sysctl_rmem        = sysctl_tcp_rmem,
    .max_header     = MAX_TCP_HEADER,
    .obj_size       = sizeof(struct tcp_sock),
    .slab_flags     = SLAB_DESTROY_BY_RCU,
    .twsk_prot      = &tcp_timewait_sock_ops,
    .rsk_prot       = &tcp_request_sock_ops,
    .h.hashinfo     = &tcp_hashinfo,
    .no_autobind        = true,
#ifdef CONFIG_COMPAT
    .compat_setsockopt  = compat_tcp_setsockopt,
    .compat_getsockopt  = compat_tcp_getsockopt,
#endif
#ifdef CONFIG_MEMCG_KMEM
    .init_cgroup        = tcp_init_cgroup,
    .destroy_cgroup     = tcp_destroy_cgroup,
    .proto_cgroup       = tcp_proto_cgroup,
#endif
};
EXPORT_SYMBOL(tcp_prot);

So I notice that there is no entry in this struct for the "bind()" function! The proto struct for SCTP, which is defined as sctp_prot, has a listing for the find bind function(which hooks to sctp_bind)but where is the tcp socket bind function? I ask this because in fact, the bind function in the GCC sockets API has been giving me trouble for TCP sockets; and out of sheer curiosity.

Answer 1

It's over in net/ipv4/af_inet.c

const struct proto_ops inet_stream_ops = {
        .family            = PF_INET,
        .owner             = THIS_MODULE,
        .release           = inet_release,
        .bind              = inet_bind,      <---- here
        .connect           = inet_stream_connect,
        .socketpair        = sock_no_socketpair,
        .accept            = inet_accept,
        .getname           = inet_getname,
        .poll              = tcp_poll,
...