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First time attempting multi-player with UDP sockets, weird error

Started by Tim Lawton Apr 11, 2013 at 1:04 PM 8 replies 2k views

Original Post

Tim Lawton

Apr 11, 2013 at 1:04 PM

Hey guys,

Pretty much all the details in the title, I've no errors from the client side, but this is the server side code:

SERVER


void Application::Init_Winsock()
{
	WSAStartup(MAKEWORD(2,2), &Winsock);

	if(LOBYTE(Winsock.wVersion) !=2 || HIBYTE(Winsock.wVersion) !=2)	//Check Version
	{
		WSACleanup();	//Cleanup and end if not version 2
		return;
	}

	//Create Socket
	Socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

	//Input Reciever Information
	ZeroMemory(&RemoteAddress, sizeof(RemoteAddress));		//Clear Struct
	RemoteAddress.sin_family = AF_INET;						//Set the Family Address
	RemoteAddress.sin_port = SERVER_PORT;					//Set Port
	bind(Socket, (sockaddr*)&RemoteAddress, sizeof(RemoteAddress));

	//Start the recieve thread
	CreateThread(NULL, 0, RecvThread, NULL, 0, NULL);
}

DWORD WINAPI Application::RecvThread(LPVOID knock)
{
	while(true)
	{
		PLAYER Recv;
		recvfrom(Socket, (char*)&Recv, sizeof(PLAYER), 0, (sockaddr*)&RemoteAddress, &SizeInt);

		Player = Recv;
	}
}

And heres the error:

Im clueless guys, from the tutorial Im using this should work?

patrrr

Apr 11, 2013 at 1:26 PM

Is the RecvThread function static? Otherwise, it also expects a 'this' pointer to work on, which is usually what you pass in the first parameter ('knock') in these cases.

Tim Lawton

Apr 11, 2013 at 1:37 PM

I believe so, its declared in the header file like so:


private:

DWORD WINAPI RecvThread(LPVOID);

patrrr

Apr 11, 2013 at 1:45 PM

Then it's not static, it would look like this if it was:


static DWORD WINAPI RecvThread(LPVOID);

I can see you're also using class instance variables in RecvThread; "Socket", "RemoteAddress", etc. They're not accessible due to the function being static.

You can use "knock" as the object instance, like this:


DWORD WINAPI Application::RecvThread(LPVOID knock)
{
	Application *instance = static_cast<Application *>(knock);
	while(true)
	{
		PLAYER Recv;
		recvfrom(instance->Socket, (char*)&Recv, sizeof(PLAYER), 0, (sockaddr*)&instance->RemoteAddress, &SizeInt);

		Player = Recv;
	}
}

Andrey Buhtojarov

Apr 11, 2013 at 1:48 PM

Then it's not static, it would look like this if it was:
static DWORD WINAPI RecvThread(LPVOID);
I can see you're also using class instance variables in RecvThread; "Socket", "RemoteAddress", etc. They're not accessible due to the function being static.

You can use "knock" as the object instance, like this:
DWORD WINAPI Application::RecvThread(LPVOID knock)
{
	Application *instance = static_cast<Application *>(knock);
	while(true)
	{
		PLAYER Recv;
		recvfrom(instance->Socket, (char*)&Recv, sizeof(PLAYER), 0, (sockaddr*)&instance->RemoteAddress, &SizeInt);

		Player = Recv;
	}
}

Pass this pointer like arg into the thread. In the thread cast PVOID to you object pointer and use it.

Tim Lawton

Apr 11, 2013 at 2:03 PM

Sorry guys, I don't understand what you mean. I'm not very good with understanding the correct terms of things

Andrey Buhtojarov

Apr 11, 2013 at 2:34 PM

Sorry guys, I don't understand what you mean. I'm not very good with understanding the correct terms of things

Declare as static:


private:

static DWORD WINAPI RecvThread(LPVOID);

Pass instance pointer as thead parametr:


...
    RemoteAddress.sin_port = SERVER_PORT;                    //Set Port
    bind(Socket, (sockaddr*)&RemoteAddress, sizeof(RemoteAddress));

    //Start the recieve thread
    CreateThread(NULL, 0, RecvThread, (void *)this, 0, NULL);
}

Then it's not static, it would look like this if it was:
static DWORD WINAPI RecvThread(LPVOID);
I can see you're also using class instance variables in RecvThread; "Socket", "RemoteAddress", etc. They're not accessible due to the function being static.

You can use "knock" as the object instance, like this:
DWORD WINAPI Application::RecvThread(LPVOID knock)
{
	Application *instance = static_cast<Application *>(knock);
	while(true)
	{
		PLAYER Recv;
		recvfrom(instance->Socket, (char*)&Recv, sizeof(PLAYER), 0, (sockaddr*)&instance->RemoteAddress, &SizeInt);

		Player = Recv;
	}
}

And you must correctly finish the thread. You can use this http://msdn.microsoft.com/ru-RU/library/windows/desktop/ms682396(v=vs.85).aspxhttp://msdn.microsoft.com/ru-RU/library/windows/desktop/ms682396(v=vs.85).aspx