Xin Long <lucien....@gmail.com> wrote:
> BTW, I'm also thinking to use udp_sock_create(), the only problem I can
> see is it may not do bind() in rxrpc_open_socket(), is that true? or we
> can actually bind to some address when a local address is not supplied?
If a local address isn't explicitly bound to the AF_RXRPC socket, binding the
UDP socket to a random local port is fine. In fact, sometimes I want to
explicitly bind an rxrpc server socket to a random port. See fs/afs/rxrpc.c
function afs_open_socket():
/* bind the callback manager's address to make this a server socket */
memset(&srx, 0, sizeof(srx));
srx.srx_family = AF_RXRPC;
srx.srx_service = CM_SERVICE;
srx.transport_type = SOCK_DGRAM;
srx.transport_len = sizeof(srx.transport.sin6);
srx.transport.sin6.sin6_family = AF_INET6;
srx.transport.sin6.sin6_port = htons(AFS_CM_PORT);
...
ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
if (ret == -EADDRINUSE) {
srx.transport.sin6.sin6_port = 0;
^^^ That's hoping to get a random port bound.
ret = kernel_bind(socket, (struct sockaddr *) &srx,
sizeof(srx));
}
if (ret < 0)
goto error_2;
The client cache manager server socket here is used to receive notifications
back from the fileserver. There's a standard port (7001) for the service, but
if that's in use, we can use any other port. The fileserver grabs the source
port from incoming RPC requests - and then uses that when sending 3rd-party
change notifications back.
If you could arrange for a random port to be assigned in such a case (and
indicated back to the caller), that would be awesome. Possibly I just don't
need to actually use bind in this case.
David
