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socket programming Client and Server bugs

mindoo (56)
Hey everyone,
I'm following this tutorial over at msdn :
https://msdn.microsoft.com/en-us/library/windows/desktop/ms737629%28v=vs.85%29.aspx

And I've come to the end of the tutorial wher I have both codes for Client and Server. But when I was testing the connection between the two proggramms, I noticed a couple of wierd things along with a couple of bugs:

NOTE : I'm using Visual Studios 2013 express version
NOTE : I'm running a 64bit version of windows
NOTE : As a test ip addresse, for the connection, I'm using 127.0.0.1 which is supposed to be the local ip addresse.

-Even if I don't launch the server, the client still says that bytes where sent.
-When I launch the server, it doesn't say anything about bytes it should have received.
-The server doesn't send nything
-And since the server doesn't send anything, the client doesn't receive anything.

I think the client connects to something else than the server which causes it to send data somewhere else than to the server.


Here's my client code
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#include <WinSock2.h>
#include <WS2tcpip.h>
#include <stdio.h>
#include <iostream>

#pragma comment(lib, "Ws2_32.lib")

int main(int argc, char **argv)
{
	WSADATA wsaData; //creating a WSADATA object

	int iResult;

	//Initialize winsock
	iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
	if (iResult != 0) //Checking for initialization errors
	{
		printf("WSA Startup failed : %d\n", iResult);
		return 1;
	}

	struct addrinfo *result = NULL,
					*ptr = NULL,
					hints;

	ZeroMemory(&hints, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;

	#define DEFAULT_PORT "27015"

	//Resolve the server and the port
	//The ip adress goes where argv is
	#define IP "127.0.0.1"
	iResult = getaddrinfo(IP, DEFAULT_PORT, &hints, &result);
	if (iResult != 0) //Checking for errors
	{
		printf("getaddrinfo failed: %d\n", iResult);
		WSACleanup();
		return 1;
	}

	SOCKET ConnectSocket = INVALID_SOCKET; //Creating a socket object

	//Attempt to connect to the first address returned by
	//the call to getaddrinfo
	ptr = result;

	//Create a SOCKET for connecting to server
	ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);

	//Check for errors to ensure that the socket is a valid socket
	if (ConnectSocket == INVALID_SOCKET)
	{
		printf("Error at socket(): %ld\n", WSAGetLastError());
		freeaddrinfo(result);
		WSACleanup();
		return 1;
	}

	//Connect to the server
	iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
	if (iResult == SOCKET_ERROR) //Checking fo general errors
	{
		closesocket(ConnectSocket);
		ConnectSocket = INVALID_SOCKET;
	}

	// Should really try the next address returned by getaddrinfo
	// if the connect call failed
	// But for this simple example we just free the resources
	// returned by getaddrinfo and print an error message

	freeaddrinfo(result);

	if (ConnectSocket == INVALID_SOCKET)
	{
		printf("Unable to connect to server!/n");
		WSACleanup();
		return 1;
	}

	//Sending and receiving data
	#define DEFAULT_BUFLEN 512

	int recvbuflen = DEFAULT_BUFLEN;
	
	char *sendbuf = "this is a test";
	char recvbuf[DEFAULT_BUFLEN];

	//Send an initial buffer
	iResult = send(ConnectSocket, sendbuf, (int)strlen(sendbuf), 0);
	if (iResult == SOCKET_ERROR)
	{
		printf("send failed: %d\n", WSAGetLastError());
		closesocket(ConnectSocket);
		WSACleanup();
		return 1;
	}

	printf("Bytes sent: %ld\n", iResult);

	// shutdown the connection for sending since no more data will be sent
	// the client can still use the ConnectSocket for receiving data
	iResult = shutdown(ConnectSocket, SD_SEND);
	if (iResult == SOCKET_ERROR)
	{
		printf("shutdown failed: %n\n", WSAGetLastError());
		closesocket(ConnectSocket);
		WSACleanup();
		return 1;
	}

	//Receive data until server closes the connection
	do
	{
		iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
		if (iResult > 0)
			printf("Bytes received: %d\n", iResult);
		else if (iResult == 0)
			printf("connection closed\n");
		else
			printf("recv failed: %d\n", WSAGetLastError());
	} while (iResult > 0);

	// shutdown the send half of the connection since no more data will be sent
	iResult = shutdown(ConnectSocket, SD_SEND);
	if (iResult == SOCKET_ERROR) {
		printf("shutdown failed: %d\n", WSAGetLastError());
		closesocket(ConnectSocket);
		WSACleanup();
		return 1;
	}

	// cleanup
	closesocket(ConnectSocket);
	WSACleanup();

	return 0;
}


Here's my server code :
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#include <WinSock2.h>
#include <WS2tcpip.h>
#include <stdio.h>
#include <iostream>

#pragma comment(lib, "Ws2_32.lib")

int main(int argc, char **argv)
{
	WSADATA wsaData; //Creating a WSADATA object
	
	int iResult;

	//Initialize winsock
	iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
	if (iResult != 0)
	{
		printf("WSAStartup failed: %d\n", iResult);
		return 1;
	}

	#define DEFAULT_PORT "27015"

	struct addrinfo *result = NULL,
					*ptr = NULL,
					hints;

	ZeroMemory(&hints, sizeof(hints));
	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	hints.ai_flags = AI_PASSIVE;

	//Resolve the local address and port to be used by the server
	iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
	if (iResult != 0)
	{
		printf("getaddrinfo failed: %d\n", iResult);
		WSACleanup();
		return 1;
	}

	SOCKET ListenSocket = INVALID_SOCKET;

	//Create a socket for the server to listen for client connections
	ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);

	if (ListenSocket == INVALID_SOCKET)
	{
		printf("Error at socket(): %ld\n", WSAGetLastError());
		freeaddrinfo(result);
		WSACleanup();
		return 1;
	}

	//Setup the TCP listening socket
	iResult = bind(ListenSocket, result->ai_addr, (int)result->ai_addrlen);
	if (iResult == SOCKET_ERROR)
	{
		printf("bind failed with error: %d\n", WSAGetLastError());
		freeaddrinfo(result);
		closesocket(ListenSocket);
		WSACleanup();
		return 1;
	}
	
	freeaddrinfo(result);	//Once the bind function is called, the address information is no longer needed
							//So we free up memory

	//Listening on the socket
	if (listen(ListenSocket, SOMAXCONN) == SOCKET_ERROR)
	{
		printf("Listen failed with error; %ld\n", WSAGetLastError());
		closesocket(ListenSocket);
		WSACleanup();
		return 1;
	}

	SOCKET ClientSocket;//SOCKET Object
	
	ClientSocket = INVALID_SOCKET;

	//Accept a client socket
	ClientSocket = accept(ListenSocket, NULL, NULL);
	if (ClientSocket == INVALID_SOCKET)
	{
		printf("Accept failed: %d\n", WSAGetLastError());
		closesocket(ListenSocket);
		WSACleanup();
		return 1;
	}

	#define DEFAULT_BUFLEN 512

	char recvbuf[DEFAULT_BUFLEN];
	int iSendResult;
	int recvbuflen = DEFAULT_BUFLEN;

	//Receive until the peer shuts down the connection
	do
	{
		iResult = recv(ClientSocket, recvbuf, recvbuflen, 0);
		for (int i = 0; i < 50; i++)
		{
			std::cout << "test" << std::endl;
		}
		std::cout << iResult << std::endl;
		if (iResult > 0)
		{
			printf("Bytes received: %d\n", iResult);

			//Echo the buffer back to the sender
			iSendResult = send(ClientSocket, recvbuf, iResult, 0);
			if (iSendResult == SOCKET_ERROR)
			{
				printf("send failed: %d\n", WSAGetLastError());
				closesocket(ClientSocket);
				WSACleanup();
				return 1;
			}

			printf("Bytes sent: %d\n", iSendResult);
		}
		else if (iResult == 0)
			printf("Connection closing...\n");
		else
		{
			printf("recv failed: %d\n", WSAGetLastError());
			closesocket(ClientSocket);
			WSACleanup();
			return 1;
		}
	} while (iResult > 0);

	//shutdown the send half connection since no more data will be sent
	iResult = shutdown(ClientSocket, SD_SEND);
	if (iResult == SOCKET_ERROR)
	{
		printf( "Shutdown failed: %d\n", WSAGetLastError() );
		closesocket(ClientSocket);
		WSACleanup();
		return 1;
	}

	//Cleanup
	closesocket(ClientSocket);
	WSACleanup();

	return 0;
}


Please tell me what you think of my problem and help me understand what I need to change in my code.

mindoo
koothkeeper (429)
Run netstat -n and see if your ips and sockets show up.
mindoo (56)
Ok.
I ran that command line and there's only one 127.0.0.1 ip address with port 27015 that shows up and it says state : TIME_WAIT
Why does it say that ?
thanks for your answer,
mindoo
koothkeeper (429)
That state is one of the states that a socket goes through. This link is helpful:

https://en.wikipedia.org/wiki/Transmission_Control_Protocol

About half-way down you can find the states.
mindoo (56)
I looked at your link and it didn't really help me.
I actually realized that when I run the netstat command line without the client or server, it still tells me there is a connection on port 27015 and 127.0.0.1.
Could someone please tell me what my proggramm is actually doing ?

thanks,

mindoo
tcs (519)
In your client code at line 128 you may want to shutdown the socket for reading. I'm not sure if this may help. I not really skilled in MS-Windows stuff but maybe it helps for one or another problem?
mindoo (56)
@tcs
It's what I initially thought would cause the problem but on the tutorial page, they don't say anything about closing that half so I didn't.
mindoo (56)
I initially thought that I didn't need to open the port since I was doing it on the same computer, but do you guys think I might have to open the port on the windows firewall ?
Any kind of answer would be greatly appreciated,

Mindoo
mindoo (56)
Hi,
I solved the error. All I did was change the port and it worked.
Thanks for your answers,
mindoo
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