add setKeepAlive function, which enables and sets the TCP keep-alive timer

doc/api.markdown

@@ -2042,6 +2042,15 @@ Disables the Nagle algorithm. By default TCP connections use the Nagle
 algorithm, they buffer data before sending it off. Setting `noDelay` will
 immediately fire off data each time `stream.write()` is called.
 
+### stream.setKeepAlive(enable=false, initialDelay)
+
+Enable/disable keep-alive functionality, and optionally set the initial
+delay before the first keepalive probe is sent on an idle stream.
+Set `initialDelay` (in milliseconds) to set the delay between the last
+data packet received and the first keepalive probe. Setting 0 for
+initialDelay will leave the value unchanged from the default
+(or previous) setting.
+
 
 ## DNS
 

lib/net.js

@@ -38,6 +38,7 @@ var read        = binding.read;
 var write       = binding.write;
 var toRead      = binding.toRead;
 var setNoDelay  = binding.setNoDelay;
+var setKeepAlive= binding.setKeepAlive;
 var socketError = binding.socketError;
 var getsockname = binding.getsockname;
 var errnoException = binding.errnoException;
@@ -744,9 +745,17 @@ Stream.prototype.address = function () {
 
 
 Stream.prototype.setNoDelay = function (v) {
-  if (this.type == 'tcp') setNoDelay(this.fd, v);
+  if ((this.type == 'tcp4')||(this.type == 'tcp6')) {
+    setNoDelay(this.fd, v);
+  }
 };
 
+Stream.prototype.setKeepAlive = function (enable, time) {
+  if ((this.type == 'tcp4')||(this.type == 'tcp6')) {
+    var secondDelay = Math.ceil(time/1000);
+    setKeepAlive(this.fd, enable, secondDelay);
+  }
+};
 
 Stream.prototype.setTimeout = function (msecs) {
   timeout.enroll(this, msecs);

src/node_net2.cc

@@ -1062,11 +1062,43 @@ static Handle<Value> SetNoDelay(const Arguments& args) {
   if (r < 0) {
     return ThrowException(ErrnoException(errno, "setsockopt"));
   }
-
   return Undefined();
 }
 
 
+static Handle<Value> SetKeepAlive(const Arguments& args) {
+  int r;
+  HandleScope scope;
+
+  bool enable = false;
+  int time = 0;
+
+  FD_ARG(args[0])
+
+  if (args.Length() > 0) enable = args[1]->IsTrue();
+  if (enable == true) {
+    time = args[2]->Int32Value();
+  }
+
+  int flags = enable ? 1 : 0;
+  r = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (void *)&flags, sizeof(flags));
+  if ((time > 0)&&(r >= 0)) {
+#if defined(__APPLE__)
+    // Mac uses a different setting name than Linux
+    r = setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE, (void *)&time, sizeof(time));
+#elif defined(__sun)
+    // Solaris doesn't support TCP_KEEPIDLE, so do nothing here
+#else
+    // assume anything else uses the Linux/BSD method
+    r = setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, (void *)&time, sizeof(time));
+#endif
+  }
+  if (r < 0) {
+    return ThrowException(ErrnoException(errno, "setsockopt"));
+  }
+  return Undefined();
+}
+
 //
 // G E T A D D R I N F O
 //
@@ -1287,6 +1319,7 @@ void InitNet2(Handle<Object> target) {
   NODE_SET_METHOD(target, "socketError", SocketError);
   NODE_SET_METHOD(target, "toRead", ToRead);
   NODE_SET_METHOD(target, "setNoDelay", SetNoDelay);
+  NODE_SET_METHOD(target, "setKeepAlive", SetKeepAlive);
   NODE_SET_METHOD(target, "getsockname", GetSockName);
   NODE_SET_METHOD(target, "getpeername", GetPeerName);
   NODE_SET_METHOD(target, "getaddrinfo", GetAddrInfo);

test/simple/test-tcp-keepalive.js

@@ -0,0 +1,28 @@
+require("../common");
+net = require('net');
+
+var serverConnection;
+var echoServer = net.createServer(function (connection) {
+  serverConnection = connection;
+  connection.setTimeout(0);
+  assert.notEqual(connection.setKeepAlive,undefined);
+  // send a keepalive packet after 1000 ms
+  connection.setKeepAlive(true,1000);
+  connection.addListener("end", function () {
+    connection.end();
+  });
+});
+echoServer.listen(PORT);
+
+var clientConnection = net.createConnection(PORT);
+clientConnection.setTimeout(0);
+
+setTimeout( function() {
+  // make sure both connections are still open
+  assert.equal(serverConnection.readyState,"open");
+  assert.equal(clientConnection.readyState,"open");
+  serverConnection.end();
+  clientConnection.end();
+  echoServer.close();
+}, 1200);
+