CODEWITHSUNDEEP
c++11winsock2
Yura
Yura

Reputation: 1174

Windows sockets. FD_ISSET always returns 0

I try to write Windows server app that accepts requests. I wan to use select() function to receive new connections and requests -- to monitor listen socket and previously established connections.

The problem is that FD_ISSET always returns 0. Here's the code. Can you please point me the mistake?

WORD wVersionRequested;
WSADATA wsaData;
int iResult;

// Initializing WSA 
wVersionRequested = MAKEWORD( 2, 2 );
iResult = WSAStartup( wVersionRequested, &wsaData );

if ( iResult != 0 )
{
    std::cout << "WSAStartup failed with error: " << WSAGetLastError() << std::endl;
    return false;
}

if ( LOBYTE( wsaData.wVersion ) != 2 || HIBYTE( wsaData.wVersion ) != 2 )
{
    WSACleanup();
    std::cout << "Could not find a usable version of Winsock.dll" << std::endl;
    return false;
}

int iResult;

struct addrinfo *result = NULL;
struct addrinfo hints;

std::stringstream ss;
ss << DEFAULT_PORT;

memset( &hints, 0, sizeof( hints ) );
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;


// Resolve the server address and port
iResult = getaddrinfo( NULL, ss.str().c_str(), &hints, &result );
if ( iResult != 0 )
{
    std::cout << "getaddrinfo() failed with error: " << WSAGetLastError() << std::endl;
    return false;
}


// Create a SOCKET for connecting to server
m_listenSocket = socket( result->ai_family, result->ai_socktype, result->ai_protocol );
if ( m_listenSocket == INVALID_SOCKET )
{
    std::cout << "socket() failed with error: " << WSAGetLastError() << std::endl;
    return false;
}


// Setup the TCP listening socket
iResult = bind( m_listenSocket, result->ai_addr, ( int ) result->ai_addrlen );
if ( iResult == SOCKET_ERROR )
{
    std::cout << "bind() failed with error: " << WSAGetLastError() << std::endl;
    freeaddrinfo( result );
    return false;
}

freeaddrinfo( result );

// Listen for the TCP listening socket
if ( listen( m_listenSocket, SOMAXCONN ) == SOCKET_ERROR )
{
    std::cout << "listen() failed with error: " << WSAGetLastError() << std::endl;
    return false;
}   

fd_set active_fd_set;
fd_set read_fd_set;

// Initialize the set of active sockets.
FD_ZERO( &active_fd_set );
FD_SET( m_listenSocket, &active_fd_set );

while ( !m_forceStopMessages )
{


    read_fd_set = active_fd_set;
    int retVal = select( FD_SETSIZE, &read_fd_set, NULL, NULL, NULL );
    if ( retVal < 0 )
    {
        std::cout << "select() failed with error: " << WSAGetLastError() << std::endl;
    }

    int readySockets = ( FD_SETSIZE < retVal ) ? FD_SETSIZE : retVal;

    // Service all the sockets with input pending.
    for ( int i = 0; i < readySockets; ++i )
    {
        if ( FD_ISSET( i, &read_fd_set ) )
        {
            if ( i == m_listenSocket )
            {
                // Accept a client socket

                FD_SET( clientSocket, &active_fd_set );
            }
            else
            {
                /* Data arriving on an already-connected socket. */
                FD_CLR( i, &active_fd_set );
            }
        }

    }
}

Upvotes: 0

Views: 1044

Answers (1)

Igor Tandetnik
Igor Tandetnik

Reputation: 52621

FD_ISSET takes a socket handle as the first parameter, not an index.

Upvotes: 1

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