WinHttpRequest gzip response parsing - vba

Question

I'm using MSXML2.XMLHTTP60 for http surfing in my VBA project. The issue is MSXML2.XMLHTTP60 is limited to four concurrent requests.
I'm trying to use WinHttp.WinHttpRequest.5.1 instead, and there is another issue. MSXML2.XMLHTTP60 parses gzip result automatically, but
WinHttpRequest.responseText method fails with error:
No mapping for the unicode character exists in the target multi-byte code page.
How can I parse this result with standard Windows libraries?
Code examples:
MSXML2.XMLHTTP60 limitation:
Public req1 As MSXML2.XMLHTTP60
Public req2 As MSXML2.XMLHTTP60
Public req3 As MSXML2.XMLHTTP60
Public req4 As MSXML2.XMLHTTP60
Public req5 As MSXML2.XMLHTTP60
Private Const url As String = "http://speedtest.tele2.net/100MB.zip"
Public Sub ConcurrentIssue()
Set req1 = New MSXML2.XMLHTTP60
req1.Open "get", url, True
Set req2 = New MSXML2.XMLHTTP60
req2.Open "get", url, True
Set req3 = New MSXML2.XMLHTTP60
req3.Open "get", url, True
Set req4 = New MSXML2.XMLHTTP60
req4.Open "get", url, True
Set req5 = New MSXML2.XMLHTTP60
req5.Open "get", url, True
req1.send
req2.send
req3.send
req4.send
'This query will be wait
req5.send
End Sub
Problem is that WinHttp.WinHttpRequest.5.1 does not support decompression (proof link: https://msdn.microsoft.com/ru-ru/library/windows/desktop/hh227298(v=vs.85).aspx).
I need to decompress the response myself.
Decompression issue example:
Public Sub DecompressOk()
Set req1 = New MSXML2.XMLHTTP60
req1.Open "get", "http://www.google.ru", False
req1.setRequestHeader "User-Agent", "Fiddler"
req1.setRequestHeader "Accept-Encoding", "gzip, deflate"
req1.send
Debug.Print req1.responseText
End Sub
Public Sub WithoutDecompress()
Dim req As WinHttp.WinHttpRequest
Set req = New WinHttp.WinHttpRequest
req.Open "get", "http://www.google.ru", False
req.setRequestHeader "User-Agent", "Fiddler"
req.setRequestHeader "Accept-Encoding", "gzip, deflate"
req.send
Debug.Print req.responseText
End Sub
I was trying to do this trick without success:
Public Sub DecompressIssue()
Dim req As WinHttp.WinHttpRequest
Set req = New WinHttp.WinHttpRequest
req.Open "get", "http://www.google.ru", False
req.setRequestHeader "User-Agent", "Fiddler"
req.setRequestHeader "Accept-Encoding", "gzip, deflate"
req.send
SaveBinaryToFile req.responseBody, "C:\test.zip"
Dim xmlReq As MSXML2.XMLHTTP60
Set xmlReq = New MSXML2.XMLHTTP60
xmlReq.Open "get", "C:\test.zip", False
xmlReq.setRequestHeader "Accept-Encoding", "gzip, deflate"
xmlReq.setRequestHeader "Content-Type", "text/html; charset=windows-1251"
xmlReq.send
Debug.Print xmlReq.responseBody
End Sub
Sub SaveBinaryToFile(arrBytes() As Byte, strPath As String)
With CreateObject("ADODB.Stream")
.Type = 1 ' adTypeBinary
.Open
.Write arrBytes
.SaveToFile strPath, 2 ' adSaveCreateOverWrite
.Close
End With
End Sub

Answer 1

This answer confirms the comment made by omegastripes.
.setRequestHeader "Accept-Encoding", "identity" is the right answer!
I've searched for days for a way to decode the gzipped response, but wasn't aware we could tell the server to not compress the response.