WinHttpWebSocketSample.bas

Attribute VB_Name = "WinHttpWebSocketSample"
Option Explicit

' original sample code, pulled from:
' https://github.com/microsoft/Windows-classic-samples/blob/master/Samples/WinhttpWebsocket/cpp/WinhttpWebsocket.cpp

'// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
'// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
'// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
'// PARTICULAR PURPOSE.
'//
'// Copyright (c) Microsoft Corporation. All rights reserved

'#include <Windows.h>
'#include <WinHttp.h>
'#include <stdio.h>

'int __cdecl wmain()
'{
'    DWORD dwError = ERROR_SUCCESS;
'    BOOL fStatus = FALSE;
'    HINTERNET hSessionHandle = NULL;
'    HINTERNET hConnectionHandle = NULL;
'    HINTERNET hRequestHandle = NULL;
'    HINTERNET hWebSocketHandle = NULL;
'    BYTE rgbCloseReasonBuffer[123];
'    BYTE rgbBuffer[1024];
'    BYTE *pbCurrentBufferPointer = rgbBuffer;
'    DWORD dwBufferLength = ARRAYSIZE(rgbBuffer);
'    DWORD dwBytesTransferred = 0;
'    DWORD dwCloseReasonLength = 0;
'    USHORT usStatus = 0;
'    WINHTTP_WEB_SOCKET_BUFFER_TYPE eBufferType;
'    INTERNET_PORT Port = INTERNET_DEFAULT_HTTP_PORT;
'    const WCHAR *pcwszServerName = L"localhost";
'    const WCHAR *pcwszPath = L"/WinHttpWebSocketSample/EchoWebSocket.ashx";
'    const WCHAR *pcwszMessage = L"Hello world";
'    const DWORD cdwMessageLength = ARRAYSIZE(L"Hello world") * sizeof(WCHAR);

 '   //
 '   // Create session, connection and request handles.
 '   //

 '   hSessionHandle = WinHttpOpen(L"WebSocket sample",
 '                                WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
 '                                NULL,
 '                                NULL,
 '                                0);
 '   if (hSessionHandle == NULL)
 '   {
 '       dwError = GetLastError();
 '       goto quit;
 '   }

 '   hConnectionHandle = WinHttpConnect(hSessionHandle,
 '                                      pcwszServerName,
 '                                      Port,
 '                                      0);
 '   if (hConnectionHandle == NULL)
 '   {
 '       dwError = GetLastError();
 '       goto quit;
 '   }

'    hRequestHandle = WinHttpOpenRequest(hConnectionHandle,
'                                        L"GET",
'                                        pcwszPath,
'                                        NULL,
'                                        NULL,
'                                        NULL,
'                                        0);
'    if (hRequestHandle == NULL)
'    {
'        dwError = GetLastError();
'        goto quit;
'    }

'    //
'    // Request protocol upgrade from http to websocket.
'    //
'#pragma prefast(suppress:6387, "WINHTTP_OPTION_UPGRADE_TO_WEB_SOCKET does not take any arguments.")
'    fStatus = WinHttpSetOption(hRequestHandle,
'                               WINHTTP_OPTION_UPGRADE_TO_WEB_SOCKET,
'                               NULL,
'                               0);
'    if (!fStatus)
'    {
'        dwError = GetLastError();
'        goto quit;
'    }

'    //
'    // Perform websocket handshake by sending a request and receiving server's response.
'    // Application may specify additional headers if needed.
'    //

'    fStatus = WinHttpSendRequest(hRequestHandle,
'                                 WINHTTP_NO_ADDITIONAL_HEADERS,
'                                 0,
'                                 NULL,
'                                 0,
'                                 0,
'                                 0);
'    if (!fStatus)
'    {
'        dwError = GetLastError();
'        goto quit;
'    }

'    fStatus = WinHttpReceiveResponse(hRequestHandle, 0);
'    if (!fStatus)
'    {
'        dwError = GetLastError();
'        goto quit;
'    }

'    //
'    // Application should check what is the HTTP status code returned by the server and behave accordingly.
'    // WinHttpWebSocketCompleteUpgrade will fail if the HTTP status code is different than 101.
'    //

'    hWebSocketHandle = WinHttpWebSocketCompleteUpgrade(hRequestHandle, NULL);
'    if (hWebSocketHandle == NULL)
'    {
'        dwError = GetLastError();
'        goto quit;
'    }

'    //
'    // The request handle is not needed anymore. From now on we will use the websocket handle.
'    //

'    WinHttpCloseHandle(hRequestHandle);
'    hRequestHandle = NULL;

'    wprintf(L"Succesfully upgraded to websocket protocol\n");

'    //
'    // Send and receive data on the websocket protocol.
'    //

'    dwError = WinHttpWebSocketSend(hWebSocketHandle,
'                                   WINHTTP_WEB_SOCKET_BINARY_MESSAGE_BUFFER_TYPE,
'                                   (PVOID)pcwszMessage,
'                                   cdwMessageLength);
'    if (dwError != ERROR_SUCCESS)
'    {
'        goto quit;
'    }

'    wprintf(L"Sent message to the server: '%s'\n", pcwszMessage);

'    Do
'    {
'        if (dwBufferLength == 0)
'        {
'            dwError = ERROR_NOT_ENOUGH_MEMORY;
'            goto quit;
'        }

'        dwError = WinHttpWebSocketReceive(hWebSocketHandle,
'                                          pbCurrentBufferPointer,
'                                          dwBufferLength,
'                                          &dwBytesTransferred,
'                                          &eBufferType);
'        if (dwError != ERROR_SUCCESS)
'        {
'            goto quit;
'        }

'        //
'        // If we receive just part of the message restart the receive operation.
'        //

'        pbCurrentBufferPointer += dwBytesTransferred;
'        dwBufferLength -= dwBytesTransferred;
'    }
'    while (eBufferType == WINHTTP_WEB_SOCKET_BINARY_FRAGMENT_BUFFER_TYPE);

'    //
'    // We expected server just to echo single binary message.
'    //

'    if (eBufferType != WINHTTP_WEB_SOCKET_BINARY_MESSAGE_BUFFER_TYPE)
'    {
'        wprintf(L"Unexpected buffer type\n");
'        dwError = ERROR_INVALID_PARAMETER;
'        goto quit;
'    }

'    wprintf(L"Received message from the server: '%.*s'\n", dwBufferLength, (WCHAR*)rgbBuffer);

'    //
'    // Gracefully close the connection.
'    //

'    dwError = WinHttpWebSocketClose(hWebSocketHandle,
'                                    WINHTTP_WEB_SOCKET_SUCCESS_CLOSE_STATUS,
'                                    NULL,
'                                    0);
'    if (dwError != ERROR_SUCCESS)
'    {
'        goto quit;
'    }

'    //
'    // Check close status returned by the server.
'    //

'    dwError = WinHttpWebSocketQueryCloseStatus(hWebSocketHandle,
'                                               &usStatus,
'                                               rgbCloseReasonBuffer,
'                                               ARRAYSIZE(rgbCloseReasonBuffer),
'                                               &dwCloseReasonLength);
'    if (dwError != ERROR_SUCCESS)
'    {
'        goto quit;
'    }

'    wprintf(L"The server closed the connection with status code: '%d' and reason: '%.*S'\n",
'            (int)usStatus,
'            dwCloseReasonLength,
'            rgbCloseReasonBuffer);

'quit:

'    if (hRequestHandle != NULL)
'    {
'        WinHttpCloseHandle(hRequestHandle);
'        hRequestHandle = NULL;
'    }
'
'    if (hWebSocketHandle != NULL)
'    {
'        WinHttpCloseHandle(hWebSocketHandle);
'        hWebSocketHandle = NULL;
'    }

'    if (hConnectionHandle != NULL)
'    {
'        WinHttpCloseHandle(hConnectionHandle);
'        hConnectionHandle = NULL;
'    }

'    if (hSessionHandle != NULL)
'    {
'        WinHttpCloseHandle(hSessionHandle);
'        hSessionHandle = NULL;
'    }

'    if (dwError != ERROR_SUCCESS)
'    {
'        wprintf(L"Application failed with error: %u\n", dwError);
'        return -1;
'    }

'    return 0;
'}