Friday, January 30, 2009

More on TCP/IP streaming Sockets

tcp-ip-streaming-sockets-diagram

I was writing server side code which will be reading commands from a client over a Win32 socket, problematic code was like this

// suppose m_sock is a working socket, all we gotta do is start receiving data on it

const int nBuffSize = 256;
int nRecv = 0;
char * szCmdBuff = new char [nBuffSize];
memset(szCmdBuff, 0, nBuffSize);
while(1){
nRecv = recv(m_sock, szCmdBuff, nBuffSize, 0);
// do something with the data
memset(szCmdBuff, 0, nBuffSize);
}

Problem created by this code: Junk values in input.
Solution: do memset right before calling recv

Exact code to refresh things goes like this

while(1){
memset(szCmdBuff, 0, nBuffSize);
nRecv = recv(m_sock, szCmdBuff, nBuffSize, 0);
// do something with the data
memset(szCmdBuff, 0, nBuffSize);
}

TCP IP sockets are the foundation rock of http protocol, which is the core of internet today. Having a solid understanding of how TCP/IP sockets work is essential to solve network communications problems.

cheers all...

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