AGSXMPP disconnects with Google Cloud Connection (GCM)

Connecting via XMPP to Google Cloud Connection Server (http://developer.android.com/google/gcm/ccs.html) for the purpose of sending/receiving notifications to Android devices.

Using AGSXMPP (latest version at time of writing) in a .NET4.5 Console Application to test in.

However, immediately after sending the opening XML - the connection is closed. And I cannot find any explanation.

What is sent:

<stream:stream to='gcm.googleapis.com' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0' xml:lang='en'>

Note that in the Google documenation, the stream is self-closed <stream /> where as AGSXMPP hasn't sent this - not sure if it makes a difference.

Using wireshark, I can see the message is sent in a stream, to which Google responds with a TCP Reset - the connection is then closed.

xmpp = new XmppClientConnection
         {
            UseSSL = true,
            UseStartTLS = true,
            Server = "gcm.googleapis.com",
            ConnectServer = "gcm.googleapis.com",
            Port = 5235,
            Username = "<SENDER ID>@gcm.googleapis.com",
            Password = <KEY>,
            AutoResolveConnectServer = false,
            SocketConnectionType = SocketConnectionType.Direct,
            KeepAlive = true,
         };

xmpp.Open();

I'm assuming that even if the other settings are incorrect (such as login) I should at least be able to get past this stream message and establish a connection of sorts.

Solution

There was some confusion over this scentence in the Google Documentation:

CCS requires a Transport Layer Security (TLS) connection. That means the XMPP client must initiate a TLS connection.

In relation to agsXMPP, this means UseSSL and not UseStartTLS. I had both set to true, but UseStartTLS sets UseSSL to false. Google closes the connection on a non-SSL connection. Setting UseStartTLS to false (even though the docs talking about initating with a TLS connection) - will allow a SSL connection to establish, and the connection can setup normally.

Working code:

xmpp = new XmppClientConnection
         {
            UseSSL = true,
            UseStartTLS = false,
            Server = "gcm.googleapis.com",
            ConnectServer = "gcm.googleapis.com",
            Port = 5235,
            Username = "<SENDER ID>@gcm.googleapis.com",
            Password = <KEY>,
            AutoResolveConnectServer = false,
            SocketConnectionType = SocketConnectionType.Direct,
            KeepAlive = true,
         };

xmpp.Open();