bind(...) always returning -1 using WinSock2 -- C++

Question

I'm creating a game in C++ for a university project which requires some feature of networking using Sockets. My module lecturer gave us example code of working (local machine) client/servers to show us how it works. He has the following code for setting up the socket, which works fine:

#include <winsock2.h>
#pragma comment(lib, "ws2_32.lib")

#define SERVERIP     "127.0.0.1"
#define SERVERPORT   5555

void main(){
    WSADATA w;
    int error = WSAStartup(0x0202, &w);
    if (error != 0)
    {
        die("WSAStartup failed");
    }
    if (w.wVersion != 0x0202)
    {
        die("Wrong WinSock version");
    }

    // Create a TCP socket that we'll use to listen for connections.
    SOCKET serverSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (serverSocket == INVALID_SOCKET)
    {
        die("socket failed");
    }

    // Fill out a sockaddr_in structure to describe the address we'll listen on.
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = inet_addr(SERVERIP);
    // htons converts the port number to network byte order (big-endian).
    serverAddr.sin_port = htons(SERVERPORT);

    // Bind the server socket to that address.
    if (bind(serverSocket, (const sockaddr *) &serverAddr, sizeof(serverAddr)) != 0)
    {
        die("bind failed");
    }
}

However, when I replicate most of the code, bind(...) function keeps returning -1, as opposed to the 0 in my lecturers example. Here is the relevant part of my code, using classes:

TCPSocket.h

#define SERVERIP     "127.0.0.1"
#define SERVERPORT   5555

#include <WinSock2.h>
#pragma comment(lib, "ws2_32.lib")

class TCPSocket {
public:
    TCPSocket();
    ~TCPSocket();

    void SetupServer(char* serverIP_, int serverPort_, int messageSize_);

protected:

private:

    SOCKET m_socket;
    sockaddr_in m_serverAddress;

    char* m_serverIP;
    int m_serverPort;
    int m_messageSize;
};

TCPSocket.cpp

TCPSocket::TCPSocket() {
    // Initialise WinSock Library, version 2.2
    WSADATA w;
    int error = WSAStartup(0x0202, &w);
    if(error != 0) {
        //error
        int i = 0;
    }
    if(w.wVersion != 0x0202) {
        //error
        int i = 0;
    }
}

void TCPSocket::SetupServer(char* serverIP_, int serverPort_, int messageSize_) {
    m_serverIP = serverIP_;
    m_serverPort = serverPort_;
    m_messageSize = messageSize_;

    // Create TCP socket
    m_socket = socket(AF_INET, SOCK_STREAM, 0);
    if(m_socket == INVALID_SOCKET) {
        //error
        int i = 0;
    }

    m_serverAddress.sin_family = AF_INET;
    m_serverAddress.sin_addr.s_addr = inet_addr(SERVERIP);
    m_serverAddress.sin_port = htons(SERVERPORT);       // htons: port -> network byte order (big-endian)

    // Bind server socket to address
    int bindex = bind(m_socket, (const sockaddr *) &m_serverAddress, sizeof(m_serverAddress));
    if(bindex != 0) {
        //error
        int a = 0;
    }

}

Try calling [`WSAGetLastError`](https://msdn.microsoft.com/en-us/library/windows/desktop/ms741580%28v=vs.85%29.aspx) and see which [error code](https://msdn.microsoft.com/en-us/library/windows/desktop/ms740668%28v=vs.85%29.aspx) is returned. — Paul Rooney, Nov 24 '15 at 23:46
I don't believe it's the reason for the error, but if you're passing `serverIP_` and `serverPort_` to the `SetupServer` function, why are you still using the defined macros for `SERVERIP` and `SERVERPORT` in the calls to `inet_addr()` and `htons` ? — Alnitak, Nov 24 '15 at 23:48
Just realised I made a silly mistake: I was running the `SetupServer()` function in an update loop and the error was being caught on the second iteration. — DeanoMachino, Nov 24 '15 at 23:51
@Alnitak I originally used the passed in variables, but since `m_serverIP` wasn't a `const` I felt that might've been causing an error (evidently not though). — DeanoMachino, Nov 24 '15 at 23:53
Also, a general advice: `WSAStartup` should only be called once in the program (typically somewhere at the beginning of `main`; don't forget to also call its pair `WSACleanup` at the end). Placing it in the ctor, would result it being called every time you instantiate your class (although probably not the case here if you only have one instance). — CristiFati, Nov 24 '15 at 23:56
@CristiFati Yeah, while the program is written to include the code for both the server and client, only one socket should be open for each instance of the program. — DeanoMachino, Nov 25 '15 at 00:14
Extending on @CristiFati 's point, this is SPARTA!!!! Err... C++. Make a dummy class with `WSAStartup` in the constructor and `WSACleanup` in the destructor. Then create one global instance of the dummy. Scoping handles everything for you. — user4581301, Nov 25 '15 at 00:17
You better use `getaddrinfo` to init address. you can look here for a sample: http://stackoverflow.com/questions/19431370/how-to-use-getaddrinfo-to-choose-default-free-port-for-all-interfaces — SHR, Nov 25 '15 at 00:25

score 0 · Accepted Answer · answered Nov 25 '15 at 00:16

As I said in a comment, I made a silly mistake outwith the scope of the included code: basically I was running the SetupServer() function within an update loop and the error was being caught on the second iteration of the update. Besides that, the code is perfectly functional.

bind(...) always returning -1 using WinSock2 -- C++

1 Answers1