fix: "invalid ip address" "daemon can be crashed by remote user"

Per the nodeJS documentation, a Net socket.remoteAddress value may
be undefined if the socket is destroyed, as by a client disconnect.
A multiaddr cannot be created for an invalid IP address (such as
the undefined remote address of a destroyed socket). Currently
the attempt results in a crash that can be triggered remotely. This
commit terminates processing of a destroyed socket before multiaddr
causes the crash.

fixes: #93
fixes: ipfs/js-ipfs#1447

src/listener.js

@@ -24,6 +24,12 @@ module.exports = (handler) => {
     // Avoid uncaught errors cause by unstable connections
     socket.on('error', noop)
 
+    if (socket.remoteAddress === undefined ||
+      socket.remotePort === undefined) {
+      log('connection closed before p2p connection made')
+      return
+    }
+
     const addr = getMultiaddr(socket)
     log('new connection', addr.toString())