fix: invalid ip address and 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 catches the exception in get-multiaddr and returns an
undefined value to listener rather than throwing an exception when
trying to process defective or destroyed socket data. Listener then
terminates processing of the incoming p2p connections that generate
this error condition.

fixes: https://github.com/libp2p/js-libp2p-tcp/issues/93
fixes: https://github.com/ipfs/js-ipfs/issues/1447

src/get-multiaddr.js

@@ -2,27 +2,32 @@
 
 const multiaddr = require('multiaddr')
 const Address6 = require('ip-address').Address6
+const debug = require('debug')
+const log = debug('libp2p:tcp:get-multiaddr')
 
 module.exports = (socket) => {
   let ma
 
-  if (socket.remoteFamily === 'IPv6') {
-    const addr = new Address6(socket.remoteAddress)
+  try {
+    if (socket.remoteFamily === 'IPv6') {
+      const addr = new Address6(socket.remoteAddress)
 
-    if (addr.v4) {
-      const ip4 = addr.to4().correctForm()
-      ma = multiaddr('/ip4/' + ip4 +
-        '/tcp/' + socket.remotePort
-      )
+      if (addr.v4) {
+        const ip4 = addr.to4().correctForm()
+        ma = multiaddr('/ip4/' + ip4 +
+          '/tcp/' + socket.remotePort
+        )
+      } else {
+        ma = multiaddr('/ip6/' + socket.remoteAddress +
+          '/tcp/' + socket.remotePort
+        )
+      }
     } else {
-      ma = multiaddr('/ip6/' + socket.remoteAddress +
-        '/tcp/' + socket.remotePort
-      )
+      ma = multiaddr('/ip4/' + socket.remoteAddress +
+        '/tcp/' + socket.remotePort)
     }
-  } else {
-    ma = multiaddr('/ip4/' + socket.remoteAddress +
-      '/tcp/' + socket.remotePort)
+  } catch (err) {
+    log(err)
   }
-
   return ma
 }

src/listener.js

@@ -25,6 +25,15 @@ module.exports = (handler) => {
     socket.on('error', noop)
 
     const addr = getMultiaddr(socket)
+    if (!addr) {
+      if (socket.remoteAddress === undefined) {
+        log('connection closed before p2p connection made')
+      } else {
+        log('error interpreting incoming p2p connection')
+      }
+      return
+    }
+
     log('new connection', addr.toString())
 
     const s = toPull.duplex(socket)