common: Restrict UDP binding to localhost only

Reported security vulnerability where control and data UDP
packets can be injected into the transceiver externally due
to socket binding to all interfaces using INADDR_ANY.

Existing socket interface does not allow specifying local
address; only the local port and remote address/port are
arguments.

Restrict socket bind to localhost with INADDR_LOOPBACK. If
external interfaces do need to be used, the API should be
modified to allow specifying the local socket address.

Reported-by: Simone Margaritelli <simone@zimperium.com>
Signed-off-by: Tom Tsou <tom.tsou@ettus.com>

CommonLibs/Sockets.cpp

@@ -269,7 +269,7 @@ void UDPSocket::open(unsigned short localPort)
 	size_t length = sizeof(address);
 	bzero(&address,length);
 	address.sin_family = AF_INET;
-	address.sin_addr.s_addr = INADDR_ANY;
+	address.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
 	address.sin_port = htons(localPort);
 	if (bind(mSocketFD,(struct sockaddr*)&address,length)<0) {
 		perror("bind() failed");