Packets kind of

This is a discussion on Packets kind of within the C++ Programming forums, part of the General Programming Boards category; Hi im making a packet and my main problem is trailing junk in my character arrays. Code: struct stLogin { ...

  1. #1
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    Jul 2003
    Posts
    110

    Packets kind of

    Hi im making a packet and my main problem is trailing junk in my character arrays.

    Code:
    struct stLogin
    {
     char i;
     char Username[30];
     char Password[30];
     char Unkown1;
    };
    
    
    void vClientConnection( char *szServerIP, int iServerListenPort )
    {
    	SocketObject	ClientSocketObject;
    	int i = 5;
    	stLogin LoginPacket;
    	char Overlow[62];
    	char Uname[30] = "Name";
    	char Pword[30] = "Password";
    	LoginPacket.i = 128;
    	strcpy(LoginPacket.Username,Uname);
    
    	strcpy(LoginPacket.Password,Pword);
    
    
    	cout << "<Client> Connecting to " << szServerIP << ", Port " << iServerListenPort << endl;
    	
    	// Connect to the IP and Port 
    	if( ClientSocketObject.Connect( szServerIP, iServerListenPort ) )
    	{
    		cout << "<Client> Connected" << endl;
    		
    		memcpy(Overlow,&LoginPacket,sizeof(stLogin));
    		for(i=0;i<63;i++)
    		{
    			cout << hex<<Overlow[i] << " ";
    		}
            cout << " " << endl;
    		ClientSocketObject.Send(Overlow,sizeof(stLogin),0);
    		
    		cout << "<Client> Disconnected From Server" << endl;
    	}
    	else {
    		cout << "<Client> Failed to Connect" << endl;
    	}
    }

    When I print out the Overlow it comes out like this.

    Code:
    <Client> Connecting to 192.168.1.103, Port 2593
    <Client> Connected
     N a m e   ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ P a s s w o r d
    ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠
    <Client> Disconnected From Server

    So how do I eliminate the trailing junk so its null? (btw the ╠ ╠ ╠ ╠ ╠ ╠ is the junk).


    Thankyou

  2. #2
    and the hat of wrongness Salem's Avatar
    Join Date
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    Well there's a whole bunch of problems.

    1. You dont initialise LoginPacket
    2. strcpy(LoginPacket.Username,Uname); only partially initialises the string (as far as the first \0 basically)

    So first step is begin with
    Code:
    stLogin LoginPacket = { 0 };
    > memcpy(Overlow,&LoginPacket,sizeof(stLogin));
    This assumes that the structure is packed (sizeof struct is the same as the sum of the sizes of its members). This cannot be guaranteed.
    You're in all sorts of doo-doo if you try and send a structure over the network.
    In particular, you're breaking Rule 8

    > for(i=0;i<63;i++)
    This steps off the end of the array.

    Read this as well
    Useful Links And Good Books
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
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    110
    AH yes my array was over. Also this isnt anything secure. Just something fast. But Id rather learn it the right way. Would it be better to send a class over a network?

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