Added socketTimeout option, which ensure that OS-level timeout is handled for all sockets handled by the library

lib/Connection.js

@@ -56,6 +56,7 @@ function Connection(config) {
 
   this._config = {
     socket: config.socket,
+    socketTimeout: config.socketTimeout,
     host: config.host || 'localhost',
     port: config.port || 143,
     tls: config.tls,
@@ -98,7 +99,6 @@ Connection.prototype.connect = function() {
 
   socket = config.socket || new Socket();
   socket.setKeepAlive(true);
-  socket.setTimeout(0);
   this._sock = undefined;
   this._tagcount = 0;
   this._tmrConn = undefined;
@@ -150,6 +150,21 @@ Connection.prototype.connect = function() {
   };
   this._sock.on('error', this._onError);
 
+  this._onSocketTimeout = function(){
+    clearTimeout(self._tmrConn);
+    clearTimeout(self._tmrAuth);
+    clearTimeout(self._tmrKeepalive);
+    self.state = 'disconnected';
+    self.debug && self.debug('[connection] Socket timeout');
+
+    var err = new Error('Socket timed out while talking to server');
+    err.source = 'timeout';
+    self.emit('error', err);
+    socket.destroy();
+  };
+  this._sock.on('timeout', this._onSocketTimeout);
+  socket.setTimeout(config.socketTimeout);
+
   socket.once('close', function(had_err) {
     clearTimeout(self._tmrConn);
     clearTimeout(self._tmrAuth);
@@ -1675,6 +1690,9 @@ Connection.prototype._starttls = function() {
     });
 
     self._sock.on('error', self._onError);
+    self._sock.on('timeout', this._onSocketTimeout);
+    self._sock.setTimeout(config.socketTimeout);
+
     self._parser.setStream(self._sock);
   });
 };