static extern bool WinHttpQueryHeaders(int lngHttpRequest, int lngInfoLevel, [MarshalAs(UnmanagedType.LPWStr)] string pwszHeaderName, StringBuilder buffer, ref int lngBufferLength, ref long lngIndex);

Declare Function WinHttpQueryHeaders Lib "winhttp.dll" (ByVal hRequest As IntPtr, ByVal dwInfoLevel As Integer, ByVal pwszName As String, ByVal buffer As Byte(), ByRef lpdwBufferLength As Integer, ByRef lpdwIndex As Integer) As Boolean