Winsock single client server send and receive simultaneously - c++

Question

I have a problem with simple Winsock chat application in C++. I've written a code that enables the user to choose if he wants to send data or receive the data and depending on users choice, the appropriate functions are executed. What I would like to achieve, is that the user can BOTH send and receive data. How could I approach it? Please note that I don't want to use multiple client, I just want to send and receive data by server and send and receive data by client simultaneously.
Edit: I added my code.
#include <WinSock2.h>
#include <Windows.h>
#include <iostream>
#include <string>
#include <stdio.h>
#include <ctime>
int main()
{
string IP;
int userType;
// Ask the user if he is server or client
cout << "Hi, which type of user are you? 1 - Server, 2 - Client" <<endl;
cin >> userType;
// depending on the declared user type, execute the appropriate code
if (userType == 1)
{
//initialize winsock and create a socket
WSAData wsaData; // initialize
iResult = WSAStartup(MAKEWORD(2,1), &wsaData);
if (iResult != NO_ERROR) // check for errors
cout << "Error at WSAStartup()" <<endl;
else
cout << "WSAStartup() is OK." <<endl;
// create socket
sockSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); // create a socket
if (sockSocket == INVALID_SOCKET) // check for errors
{
cout << "Error at socket(): " << WSAGetLastError();
WSACleanup();
return true;
}
else
cout << "Socket() is OK." <<endl;
return true;
// bind to socket
service.sin_addr.s_addr = inet_addr("0.0.0.0");
service.sin_family = AF_INET;
service.sin_port = htons(55555);
if (bind(sockSocket, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR) // cheking for errors
{
cout << "Bind() failed." << endl;
closesocket(sockSocket);
return true;
}
else
cout << "Bind() is OK." <<endl;
// listen
listen(sockSocket, SOMAXCONN);
if (listen(sockSocket, 10) == SOCKET_ERROR) // check for errors
{
cout << "Error listening on socket." << endl;
return true;
}
else
cout << "Listen() is OK." <<endl;
//accept connection
servlen = sizeof(service);
cout << "Waiting for user to connect..." << endl;
acceptSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if(acceptSocket = accept(sockSocket, (SOCKADDR*)&service, &servlen))
{
cout << "A coonnection was found" <<endl<<endl;
}
sockSocket = acceptSocket;
// receive messages
do
{
std::string message;
char Buffer[512];
iResult = recv(sockSocket, Buffer, 512, 0);
Buffer[iResult] = '\0';
message = Buffer;
currentDate();
std::cout << Buffer <<endl<<endl;
}while(iResult>0);
closesocket(sockSocket);
WSACleanup();
}
else if (userType == 2)
{
// exactly the same code as for server part to initialize and create socket
// ask for the ip the user wants to connect to
cout << "Hi what's the IP that you want to connect to?" <<endl;
cin >> IP;
// connect to socket
conService.sin_addr.s_addr = inet_addr(IP); // connect to the ipnuted IP
conService.sin_family = AF_INET;
conService.sin_port = htons(55555); // should the port also be the argument?
if (connect(sockSocket, (SOCKADDR*)&conService, sizeof(conService)) == SOCKET_ERROR) // check for errors
{
cout << "Failed to connect: " << WSAGetLastError();
WSACleanup();
return true;
}
else
{
cout << "Connected." <<endl;
}
// send messages
for (;;)
{
std::string message;
std::getline(std::cin, message);
unsigned int Length = strlen(message.c_str());
if(Length>512)
Length = 512;
currentDate();
iResult = send(sockSocket, message.c_str(),Length,0);
}
closesocket(sockSocket);
WSACleanup();
}
WSACleanup();
return 0;
}
Edit2: As Lemy suggested in the comment, I need to have a second thread (as the first one is simply what's going on in the main function). From what I understood, I can use CreateThread function. My problem of how to both send and receive messages is solved (I should create another thread), but now I have problem with implementing the solution. As I wrote in the comment below Lemy's answer, I get such error referring to the line where I use CreateThread function (HANDLE hThread = CreateThread(0,0,&ReadingThread,acceptSocket,0,&dwThreadID);):
invalid conversion from 'SOCKET {aka unsigned int}' to 'PVOID {aka void*}' [-fpermissive]| and
invalid conversion from 'DWORD {aka long unsigned int}' to 'PDWORD {aka long unsigned int*}' [-fpermissive]
Any hints for that? Hope this makes my question more specific(if not pls tell me what should I specify more).

Answer 1

You need to have the client and server continuously reading in the background for the lifetime of the connection, and then they can send data in parallel whenever needed. Move your reading logic into a separate thread, eg:
#include <WinSock2.h>
#include <Windows.h>
#include <iostream>
#include <string>
#include <stdio.h>
#include <ctime>
DWORD WINAPI ReadingThread(LPVOID param)
{
SOCKET s = (SOCKET) param;
char Buffer[512];
int iResult;
do
{
iResult = recv(s, Buffer, 512, 0);
if (iResult <= 0) break;
Buffer[iResult] = '\0';
std::cout << "Recv: " << message << std::endl;
}
while (true);
return 0;
}
int main()
{
int userType;
HANDLE hThread;
DWORD dwThreadID;
//initialize winsock and create a socket
WSAData wsaData; // initialize
iResult = WSAStartup(MAKEWORD(2,1), &wsaData);
if (iResult != NO_ERROR) // check for errors
{
std::cout << "Error at WSAStartup()" << std::endl;
return 0;
}
std::cout << "WSAStartup() is OK." << std::endl;
// Ask the user if he is server or client
std::cout << "Hi, which type of user are you? 1 - Server, 2 - Client" << std::endl;
std::cin >> userType;
// depending on the declared user type, execute the appropriate code
if (userType == 1)
{
// create socket
sockSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); // create a socket
if (sockSocket == INVALID_SOCKET) // check for errors
{
std::cout << "Error at socket(): " << WSAGetLastError() << std::endl;
WSACleanup();
return 0;
}
std::cout << "Socket() is OK." << std::endl;
// bind to socket
service.sin_addr.s_addr = INADDR_ANY;
service.sin_family = AF_INET;
service.sin_port = htons(55555);
if (bind(sockSocket, (SOCKADDR*)&service, sizeof(service)) == SOCKET_ERROR) // cheking for errors
{
std::cout << "Error at bind(): " << WSAGetLastError() << std::endl;
closesocket(sockSocket);
WSACleanup();
return 0;
}
std::cout << "Bind() is OK." << std::endl;
// listen
if (listen(sockSocket, 10) == SOCKET_ERROR) // check for errors
{
std::cout << "Error at listen(): " << WSAGetLastError() << std::endl;
closesocket(sockSocket);
WSACleanup();
return 0;
}
std::cout << "Listen() is OK." << std::endl;
//accept connection
servlen = sizeof(service);
std::cout << "Waiting for user to connect..." << std::endl;
acceptSocket = accept(sockSocket, (SOCKADDR*)&service, &servlen);
if (acceptSocket != INVALID_SOCKET)
{
std::cout << "Error at accept(): " << WSAGetLastError() << std::endl;
closesocket(sockSocket);
WSACleanup();
return 0;
}
std::cout << "A client has connected" << std::endl << std::endl;
// receive messages
hThread = CreateThread(NULL, 0, &ReadingThread, (void*)acceptSocket, 0, &dwThreadID);
if (!hThread)
{
std::cout << "Error at CreateThread(): " << GetLastError() << std::endl;
closesocket(acceptSocket);
closesocket(sockSocket);
WSACleanup();
return 0;
}
// send messages
do
{
std::string message;
if (!std::getline(std::cin, message))
break;
if (send(acceptSocket, msg.c_str(), msg.length(), 0) == SOCKET_ERROR)
{
std::cout << "Error at send(): " << WSAGetLastError() << std::endl;
break;
}
}
while (true);
closesocket(acceptSocket);
WaitForSingleObject(hThread, INFINITE);
CloseHandle(hThread);
closesocket(sockSocket);
WSACleanup();
}
else if (userType == 2)
{
// create socket
sockSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); // create a socket
if (sockSocket == INVALID_SOCKET) // check for errors
{
std::cout << "Error at socket(): " << WSAGetLastError() << std::endl;
WSACleanup();
return 0;
}
std::cout << "Socket() is OK." << std::endl;
// ask for the ip the user wants to connect to
std::string IP;
std::cout << "Hi what's the IP that you want to connect to?" << std::endl;
std::cin >> IP;
// connect to socket
conService.sin_addr.s_addr = inet_addr(IP.c_str()); // connect to the ipnuted IP
conService.sin_family = AF_INET;
conService.sin_port = htons(55555); // should the port also be the argument?
if (connect(sockSocket, (SOCKADDR*)&conService, sizeof(conService)) == SOCKET_ERROR) // check for errors
{
std::cout << "Failed to connect: " << WSAGetLastError() << std::endl;
closesocket(sockSocket);
WSACleanup();
return 0;
}
std::cout << "Connected." << std::endl;
// receive messages
hThread = CreateThread(NULL, 0, &ReadingThread, (void*)sockSocket, 0, &dwThreadID);
if (!hThread)
{
std::cout << "Error at CreateThread(): " << GetLastError() << std::endl;
closesocket(sockSocket);
WSACleanup();
return 0;
}
// send messages
do
{
std::string message;
if (!std::getline(std::cin, message))
break;
if (send(sockSocket, msg.c_str(), msg.length(), 0) == SOCKET_ERROR)
{
std::cout << "Error at send(): " << WSAGetLastError() << std::endl;
break;
}
}
while (true);
closesocket(sockSocket);
WaitForSingleObject(hThread, INFINITE);
CloseHandle(hThread);
WSACleanup();
}
else
{
std::cout << "Invalid type entered!" << std::endl;
WSACleanup();
return 0;
}
return 0;
}