filled in with the address of the local socket, as known to the communications layer, depending on the IP version of this class
0 success or -1 on failure. On failure errno is set appropriately.
Errors: EBADF The argument sockfd is not a valid descriptor.
EFAULT The local_address argument points to memory not in a valid part of the process address space.
ENOBUFS Insufficient resources were available in the system to perform the operation.
ENOTSOCK this.fd is a file, not a socket.
Obtains the current address to which this socket is bound.