static BOOL CALLBACK SocketExtensionInitFn()

in ctl/ctSocketExtensions.hpp [45:168]
114 lines of code
16 McCabe index (conditional complexity)

        static BOOL CALLBACK SocketExtensionInitFn(_In_ PINIT_ONCE, _In_ PVOID, _In_ PVOID*) noexcept
        {
            WSADATA wsadata;
            if (::WSAStartup(WINSOCK_VERSION, &wsadata) != 0)
            {
                return FALSE;
            }
            auto wsaCleanupOnExit = wil::scope_exit([&]() noexcept { ::WSACleanup(); });

            // check to see if need to create a temp socket
            const auto localSocket = ::socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
            if (INVALID_SOCKET == localSocket)
            {
                return FALSE;
            }
            auto closesocketOnExit = wil::scope_exit([&]() noexcept { ::closesocket(localSocket); });

            // control code and the size to fetch the extension function pointers
            for (auto fnLoop = 0ul; fnLoop < c_functionPtrCount; ++fnLoop)
            {
                VOID* functionPtr{nullptr};
                DWORD controlCode{SIO_GET_EXTENSION_FUNCTION_POINTER};
                DWORD bytes{sizeof(VOID*)};
                // must declare GUID explicitly at a global scope as some commonly used test libraries
                // - incorrectly pull it into their own namespace
                GUID guid{};

                switch (fnLoop)
                {
                    case 0:
                    {
                        functionPtr = &g_transmitfile;
                        constexpr GUID tmpGuid = WSAID_TRANSMITFILE;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 1:
                    {
                        functionPtr = &g_acceptex;
                        constexpr GUID tmpGuid = WSAID_ACCEPTEX;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 2:
                    {
                        functionPtr = &g_getacceptexsockaddrs;
                        constexpr GUID tmpGuid = WSAID_GETACCEPTEXSOCKADDRS;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 3:
                    {
                        functionPtr = &g_transmitpackets;
                        constexpr GUID tmpGuid = WSAID_TRANSMITPACKETS;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 4:
                    {
                        functionPtr = &g_connectex;
                        constexpr GUID tmpGuid = WSAID_CONNECTEX;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 5:
                    {
                        functionPtr = &g_disconnectex;
                        constexpr GUID tmpGuid = WSAID_DISCONNECTEX;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 6:
                    {
                        functionPtr = &g_wsarecvmsg;
                        constexpr GUID tmpGuid = WSAID_WSARECVMSG;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 7:
                    {
                        functionPtr = &g_wsasendmsg;
                        constexpr GUID tmpGuid = WSAID_WSASENDMSG;
                        memcpy(&guid, &tmpGuid, sizeof GUID);
                        break;
                    }
                    case 8:
                    {
                        functionPtr = &g_rioextensionfunctiontable;
                        constexpr GUID tmpGuid = WSAID_MULTIPLE_RIO;
                        ::memcpy(&guid, &tmpGuid, sizeof GUID);
                        controlCode = SIO_GET_MULTIPLE_EXTENSION_FUNCTION_POINTER;
                        bytes = {sizeof g_rioextensionfunctiontable};
                        ::ZeroMemory(&g_rioextensionfunctiontable, bytes);
                        g_rioextensionfunctiontable.cbSize = bytes;
                        break;
                    }
                    default:
                        FAIL_FAST_MSG("Unknown ctSocketExtension function number");
                }

                if (0 != ::WSAIoctl(
                        localSocket,
                        controlCode,
                        &guid,
                        static_cast<DWORD>(sizeof guid),
                        functionPtr,
                        bytes,
                        &bytes,
                        nullptr, // lpOverlapped
                        nullptr))
                {
                    if (WSAGetLastError() == WSAEOPNOTSUPP && 8 == fnLoop)
                    {
                        // ignore not-supported errors for RIO APIs to support Win7
                    }
                    else
                    {
                        return FALSE;
                    }
                }
            }

            return TRUE;
        }