The following is a simple Client Server example that actually covers quite a few different topics. The code is modified from the MadWizard.org Winsock Tutorial. It may be a good idea to go through the StringStreams example here and C/C++ String differences example here.
Please note that the code below is not the best example of coding practice.
Server code:
//Original Client-Server code from www.MadWizard.org
//Part of the Winsock networking tutorial by Thomas Bleeker
//Modified and tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include <iostream>
#include <string>
#include <sstream>
#define WIN32_MEAN_AND_LEAN
#include <winsock2.h>
#include <windows.h>
//Add ws2_32.lib in Properties->Linker->Input->Additional Dependencies
using namespace std;
const int REQ_WINSOCK_VER = 2; // Minimum winsock version required
const int DEFAULT_PORT = 4444;
const int TEMP_BUFFER_SIZE = 128;
//Forward Declarations
bool RunServer(int portNumber);
//MAIN
int main()
{
int iRet = 1;
WSADATA wsaData;
cout << "SERVER STARTED" << endl;
cout << "Initializing winsock... ";
if (WSAStartup(MAKEWORD(REQ_WINSOCK_VER,0), &wsaData)==0)
{
// Check if major version is at least REQ_WINSOCK_VER
if (LOBYTE(wsaData.wVersion) >= REQ_WINSOCK_VER)
{
cout << "initialized.\n";
int port = DEFAULT_PORT;
iRet = !RunServer(port);
}
else
{
cerr << "required version not supported!";
}
cout << "Cleaning up winsock... ";
// Cleanup winsock
if (WSACleanup()!=0)
{
cerr << "cleanup failed!\n";
iRet = 1;
}
cout << "done.\n";
}
else
{
cerr << "startup failed!\n";
}
return iRet;
}
string GetHostDescription(const sockaddr_in &sockAddr)
{
ostringstream stream;
stream << inet_ntoa(sockAddr.sin_addr) << ":" << ntohs(sockAddr.sin_port);
return stream.str();
}
void SetServerSockAddr(sockaddr_in *pSockAddr, int portNumber)
{
// Set family, port and find IP
pSockAddr->sin_family = AF_INET;
pSockAddr->sin_port = htons(portNumber);
pSockAddr->sin_addr.S_un.S_addr = INADDR_ANY;
}
void HandleConnection(SOCKET hClientSocket, const sockaddr_in &sockAddr)
{
// Print description (IP:port) of connected client
cout << "Connected with " << GetHostDescription(sockAddr) << ".\n";
exception e;
char tempBuffer[TEMP_BUFFER_SIZE];
// Read data
while(true)
{
int retval;
retval = recv(hClientSocket, tempBuffer, sizeof(tempBuffer), 0);
if (retval==0)
{
break; // Connection has been closed
}
else if (retval==SOCKET_ERROR)
{
exception e("socket error while receiving.");
throw e;
}
else
{
string tempBufferString(tempBuffer);
cout<<"Received over the socket :"<<tempBufferString<<endl;
string tempString = "Loopbacked: " + tempBufferString + '\0';
strcpy_s(tempBuffer, tempString.length() + 1, tempString.c_str());
if (send(hClientSocket, tempBuffer, strlen(tempBuffer)+1, 0)==SOCKET_ERROR)
{
exception e("socket error while sending.");
throw e;
}
}
}
cout << "Connection closed.\n";
}
bool RunServer(int portNumber)
{
SOCKET hSocket = INVALID_SOCKET, hClientSocket = INVALID_SOCKET;
bool bSuccess = true;
sockaddr_in sockAddr = {0};
try
{
// Create socket
cout << "Creating socket... ";
if ((hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET)
{
cout << "failed Creating socket... \n";
return false;
}
cout << "created.\n";
// Bind socket
cout << "Binding socket... ";
SetServerSockAddr(&sockAddr, portNumber);
if (bind(hSocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr))!=0)
{
cout << "failed Binding socket... \n";
return false;
}
cout << "bound.\n";
// Put socket in listening mode
cout << "Putting socket in listening mode... ";
if (listen(hSocket, SOMAXCONN)!=0)
{
cout << "failed Putting socket in listening mode... \n";
return false;
}
cout << "done.\n";
// Wait for connection
cout << "Waiting for incoming connection... ";
sockaddr_in clientSockAddr;
int clientSockSize = sizeof(clientSockAddr);
// Accept connection:
hClientSocket = accept(hSocket,
reinterpret_cast<sockaddr*>(&clientSockAddr),
&clientSockSize);
// Check if accept succeeded
if (hClientSocket==INVALID_SOCKET)
{
cout << "accept function failed... \n";
return false;
}
cout << "accepted.\n";
// Wait for and accept a connection:
HandleConnection(hClientSocket, clientSockAddr);
}
catch(exception& e)
{
cerr << "\nError: " << e.what() << endl;
bSuccess = false;
}
if (hSocket!=INVALID_SOCKET)
closesocket(hSocket);
if (hClientSocket!=INVALID_SOCKET)
closesocket(hClientSocket);
return bSuccess;
}
Client code:
//Original Client-Server code from www.MadWizard.org
//Part of the Winsock networking tutorial by Thomas Bleeker
//Modified and tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
#include <iostream>
#include <sstream>
#define WIN32_MEAN_AND_LEAN
#include <winsock2.h>
#include <windows.h>
using namespace std;
//Add ws2_32.lib in Properties->Linker->Input->Additional Dependencies
using namespace std;
const int REQ_WINSOCK_VER = 2; // Minimum winsock version required
const char DEF_SERVER_NAME[] = "127.0.0.1"; //localhost - can be your server name like "www.google.com"
const int SERVER_PORT = 4444;
const int TEMP_BUFFER_SIZE = 128;
// IP number typedef for IPv4
typedef unsigned long IPNumber;
//Forward Declarations
bool RunClient(const char *pServername);
//MAIN
int main(int argc, char* argv[])
{
int iRet = 1;
WSADATA wsaData;
cout << "CLIENT STARTED" << endl;
cout << "Initializing winsock... ";
if (WSAStartup(MAKEWORD(REQ_WINSOCK_VER,0), &wsaData)==0)
{
// Check if major version is at least REQ_WINSOCK_VER
if (LOBYTE(wsaData.wVersion) >= REQ_WINSOCK_VER)
{
cout << "initialized.\n";
// Set default hostname:
const char *pHostname = DEF_SERVER_NAME;
iRet = !RunClient(pHostname);
}
else
{
cerr << "required version not supported!";
}
cout << "Cleaning up winsock... ";
// Cleanup winsock
if (WSACleanup()!=0)
{
cerr << "cleanup failed!\n";
iRet = 1;
}
cout << "done.\n";
}
else
{
cerr << "startup failed!\n";
}
return iRet;
}
IPNumber FindHostIP(const char *pServerName)
{
HOSTENT *pHostent;
// Get hostent structure for hostname:
if (!(pHostent = gethostbyname(pServerName)))
{
exception e("could not resolve hostname.");
throw e;
}
// Extract primary IP address from hostent structure:
if (pHostent->h_addr_list && pHostent->h_addr_list[0])
return *reinterpret_cast<IPNumber*>(pHostent->h_addr_list[0]);
return 0;
}
void FillSockAddr(sockaddr_in *pSockAddr, const char *pServerName, int portNumber)
{
// Set family, port and find IP
pSockAddr->sin_family = AF_INET;
pSockAddr->sin_port = htons(portNumber);
pSockAddr->sin_addr.S_un.S_addr = FindHostIP(pServerName);
}
bool RunClient(const char *pServername)
{
SOCKET hSocket = INVALID_SOCKET;
char tempBuffer[TEMP_BUFFER_SIZE];
sockaddr_in sockAddr = {0};
bool bSuccess = true;
try
{
// Lookup hostname and fill sockaddr_in structure:
cout << "Looking up hostname " << pServername << "... ";
FillSockAddr(&sockAddr, pServername, SERVER_PORT);
cout << "found.\n";
// Create socket
cout << "Creating socket... ";
if ((hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == INVALID_SOCKET)
{
cout<<"could not create socket. "<<endl;
return false;
}
cout << "created.\n";
// Connect to server
cout << "Attempting to connect to " << inet_ntoa(sockAddr.sin_addr)
<< ":" << SERVER_PORT << "... ";
if (connect(hSocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr))!=0)
{
cout<<"could not connect. "<<endl;
return false;
}
cout << "connected.\n";
cout << "Sending requests and checking for loopbacks... "<<endl;
//Lets sent 100 packets and get it looped back from Server
for(int i = 0; i < 10; i++)
{
int retval = 0;
stringstream ss (stringstream::in | stringstream::out);
ss << "Message " << i <<"\n";
std::string s = ss.str() + '\0'; //Adding the null charachter
if (send(hSocket, s.c_str(), s.size() + 1, 0)==SOCKET_ERROR)
{
cout<<"failed to send data. "<<endl;
return false;
}
retval = recv(hSocket, tempBuffer, sizeof(tempBuffer), 0);
if (retval==0)
{
cout<<"Connection closed"<<endl;
break;
}
else if (retval==SOCKET_ERROR)
{
exception e("socket error while receiving.");
throw e;
}
else
{
// retval is number of bytes read
// Terminate buffer with zero and print as string
tempBuffer[retval] = 0;
cout << "Received " << retval << " bytes. Received : " <<tempBuffer;
}
}
}
catch(exception& e)
{
cerr << "\nError: " << e.what() << endl;
bSuccess = false;
}
if (hSocket!=INVALID_SOCKET)
{
closesocket(hSocket);
}
return bSuccess;
}
The Server Output is as follows:
The Client output is as follows:
