Function BaseHttp_Read

3rdParty/StormLib/src/FileStream.cpp:718–793

}

static bool BaseHttp_Read(
    TFileStream * pStream,                  // Pointer to an open stream
    ULONGLONG * pByteOffset,                // Pointer to file byte offset. If NULL, it reads from the current position
    void * pvBuffer,                        // Pointer to data to be read
    DWORD dwBytesToRead)                    // Number of bytes to read from the file
{
#ifdef PLATFORM_WINDOWS
    ULONGLONG ByteOffset = (pByteOffset != NULL) ? *pByteOffset : pStream->Base.Http.FilePos;
    DWORD dwTotalBytesRead = 0;

    // Do we have to read anything at all?
    if(dwBytesToRead != 0)
    {
        HINTERNET hRequest;
        LPCTSTR szFileName;
        LPBYTE pbBuffer = (LPBYTE)pvBuffer;
        TCHAR szRangeRequest[0x80];
        DWORD dwStartOffset = (DWORD)ByteOffset;
        DWORD dwEndOffset = dwStartOffset + dwBytesToRead;

        // Open HTTP request to the file
        szFileName = BaseHttp_ExtractServerName(pStream->szFileName, NULL);
        hRequest = HttpOpenRequest(pStream->Base.Http.hConnect, _T("GET"), szFileName, NULL, NULL, NULL, INTERNET_FLAG_NO_CACHE_WRITE, 0);
        if(hRequest != NULL)
        {
            // Add range request to the HTTP headers
            // http://www.clevercomponents.com/articles/article015/resuming.asp
            _stprintf(szRangeRequest, _T("Range: bytes=%u-%u"), (unsigned int)dwStartOffset, (unsigned int)dwEndOffset);
            HttpAddRequestHeaders(hRequest, szRangeRequest, 0xFFFFFFFF, HTTP_ADDREQ_FLAG_ADD_IF_NEW); 

            // Send the request to the server
            if(HttpSendRequest(hRequest, NULL, 0, NULL, 0))
            {
                while(dwTotalBytesRead < dwBytesToRead)
                {
                    DWORD dwBlockBytesToRead = dwBytesToRead - dwTotalBytesRead;
                    DWORD dwBlockBytesRead = 0;

                    // Read the block from the file
                    if(dwBlockBytesToRead > 0x200)
                        dwBlockBytesToRead = 0x200;
                    InternetReadFile(hRequest, pbBuffer, dwBlockBytesToRead, &dwBlockBytesRead);

                    // Check for end
                    if(dwBlockBytesRead == 0)
                        break;

                    // Move buffers
                    dwTotalBytesRead += dwBlockBytesRead;
                    pbBuffer += dwBlockBytesRead;
                }
            }
            InternetCloseHandle(hRequest);
        }
    }

    // Increment the current file position by number of bytes read
    pStream->Base.Http.FilePos = ByteOffset + dwTotalBytesRead;