Read Windows UDP Buffer Size

Question

I'm finding difficulty figuring out how to check the UDP Buffer size in Windows via Command Prompt. I am looking for something similar to the linux command "sysctl net.core.rmem_max". I do not need to set the UDP buffer size, I just need to check it in order to throw a warning if it is smaller than my recommended size. So far every where I seem to look points towards setting the buffer size through the Windows Registry. Does anyone know of a possible way to simply check the buffer size through a Command Prompt or C++?

Answer 1

I don't know how to do this from the command line (looks like PowerShell can do it), but you should be able to do this in C++ as follows (note: untested):

#include <iostream>
#include <WinSock2.h>
#include <Ws2tcpip.h>
#pragma comment (lib, "Ws2_32.lib")

int main ()
{
    WSADATA wsaData;
    int err = WSAStartup (MAKEWORD (2, 2), &wsaData);
    if (err != NO_ERROR)
    {
        std::cerr << "WSAStartup failed with error " << err << "\n";
        return 1;
    }

    SOCKET s = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if (s == INVALID_SOCKET)
    {
        std::cerr << "socket failed with error " << WSAGetLastError () << "\n"
        return 1;
    }

    int rcvbuf_len;
    socklen_t optlen = sizeof (rcvbuf_len);

    if (getsockopt (s, SOL_SOCKET, SO_RCVBUF, &rcvbuf_len, &optlen) < 0)
    {
        std::cerr << "getsockopt failed with error " << WSAGetLastError () << "\n";
        return 1;
    }

    std::cout << "UDP receive buffer length = " << rcvbuf_len << " bytes\n");
}

We don't need to clean up any resources here as that will happen automatically when the program exits.