Masterserveruplink

Why do you need to specify any master server even if you want to run a server that is not advertised?!

class MasterServerLauncher extends Info; //[3369] Issue #1
 
function BeginPlay()
{
    local MasterServerUplink M;
    local int i;

    for(i = 0; i < class'MasterServerLink'.default.MasterServerList.Length; i++)
    {
        Log("Creating master server uplink for" @ class'MasterServerLink'.default.MasterServerList[i].Address $ ":" $ class'MasterServerLink'.default.MasterServerList[i].Port, 'MasterServerLauncher');
        M = Spawn(class'MasterServerUplink');
        M.myMasterServer = i;
        //This must only be called on one master server link
        if (i == 0)
            M.UplinkAndStats();
        M.Reconnect();

        if (! class'MasterServerUplink'.default.DoUplink) break;
    }

    Destroy();
}

The MasterServerUplink object isn't solely for reporting information to a master server. It has multiple functions:

1. Establishing network play
2. Starting up the link to GameSpy, if UplinkToGamespy is requested in addition to DoUplink
3. Starting up the link to GameStats if SendStats is requested in addition to DoUplink
4. Starting up the link to a master server, if DoUplink is requested

The reason one of these objects is always required is for activity 1, even if things 2, 3 and 4 are configured off.

In the code above there is a call to M.UplinkAndStats(); which performs steps 1 to 3 from the list above. Here it is (cut down) so you can follow the logic:

function UplinkAndStats()
{
    local class<UdpLink> LinkClass;

    NetworkConnect();  // this is my point 1 above

    if( DoUplink )
    {
        if( UplinkToGamespy )
        {
            // set up link to gamespy
        }

        if( SendStats )
        {
            // set up link to stats server
        }
    }
}

The next line after M.UplinkAndStats(); in the code you quoted is a call to the C++ engine code:

M.Reconnect();

Within that engine function there is a check on DoUplink. If it is set to true, it starts up a master server link. If not, it does not establish that link and instead outputs this line in the log:

MasterServerUplink: DoUplink is False, not connecting to master server(s)