Request.BinaryRead(Request.TotalBytes) throws error for large files - asp-classic

Question

I have code that accepts binary data via POST and reads in an array of bytes. For files larger than 200 Kb, the operation fails. I've checked with my sysadmin (we're running IIS 7) to see if there was a limit in our configuration and he says there is none, and suspects it is a problem with the code. Does anybody here see any potential problems? Here is my code:
Public Sub Initialize
If Request.TotalBytes > 0 Then
Dim binData
binData = Request.BinaryRead(Request.TotalBytes) ' This line fails'
getData binData
End If
End Sub
Private Sub getData(rawData)
Dim separator
separator = MidB(rawData, 1, InstrB(1, rawData, ChrB(13)) - 1)
Dim lenSeparator
lenSeparator = LenB(separator)
Dim currentPos
currentPos = 1
Dim inStrByte
inStrByte = 1
Dim value, mValue
Dim tempValue
tempValue = ""
While inStrByte > 0
inStrByte = InStrB(currentPos, rawData, separator)
mValue = inStrByte - currentPos
If mValue > 1 Then
value = MidB(rawData, currentPos, mValue)
Dim begPos, endPos, midValue, nValue
Dim intDict
Set intDict = Server.CreateObject("Scripting.Dictionary")
begPos = 1 + InStrB(1, value, ChrB(34))
endPos = InStrB(begPos + 1, value, ChrB(34))
nValue = endPos
Dim nameN
nameN = MidB(value, begPos, endPos - begPos)
Dim nameValue, isValid
isValid = True
If InStrB(1, value, stringToByte("Content-Type")) > 1 Then
begPos = 1 + InStrB(endPos + 1, value, ChrB(34))
endPos = InStrB(begPos + 1, value, ChrB(34))
If endPos = 0 Then
endPos = begPos + 1
isValid = False
End If
midValue = MidB(value, begPos, endPos - begPos)
intDict.Add "FileName", trim(byteToString(midValue))
begPos = 14 + InStrB(endPos + 1, value, stringToByte("Content-Type:"))
endPos = InStrB(begPos, value, ChrB(13))
midValue = MidB(value, begPos, endPos - begPos)
intDict.Add "ContentType", trim(byteToString(midValue))
begPos = endPos + 4
endPos = LenB(value)
nameValue = MidB(value, begPos, ((endPos - begPos) - 1))
Else
nameValue = trim(byteToString(MidB(value, nValue + 5)))
End If
If isValid = True Then
intDict.Add "Value", nameValue
intDict.Add "Name", nameN
dict.Add byteToString(nameN), intDict
End If
End If
currentPos = lenSeparator + inStrByte
Wend
End Sub
Here is the error that appears in the logs:
Log Name: Application
Source: Active Server Pages
Date: 11/11/2010 2:15:35 PM
Event ID: 5
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: xxxxx.xxxxx.xxx
Description:
Error: File /path-to-file/loader.asp Line 36 Operation not Allowed. .
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Active Server Pages" />
<EventID Qualifiers="49152">5</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2010-11-11T19:15:35.000Z" />
<EventRecordID>19323</EventRecordID>
<Channel>Application</Channel>
<Computer>PHSWEB524.partners.org</Computer>
<Security />
</System>
<EventData>
<Data>File /mghdev/loader.asp Line 36 Operation not Allowed. </Data>
</EventData>
</Event>

Answer 1

By default the limit for the entity size in a POST request is 200K, hence your error.
You can increase that limit open IIS Manager and navigate the tree to your application. Double click the "ASP" icon in the main panel. Expand the "Limits" category. Modify the "Maximum Requesting Entity Body Limit" to a larger value.
If this is for a public web-site be careful as to the limit you set, the purpose of the limit is to prevent malicious POSTs overwhelming the site.

Answer 2

If you read the specifications of the BinaryRead method, you will see that the parameter is actually an out parameter as well. The BinaryRead method is trying to change the value of Request.TotalBytes which it can't do. TotalBytes is read-only.
You can easily fix this by assigning TotalBytes to a variable and passing that in instead. This is what the example code shows in the MSDN documentation.
If the BinaryRead read a different amount of data, the variable will reflect the size of the read.

Answer 3

Two Settings are required in IIS under the "Limit Properties" section
1- Maximum Requesting Entity Body Limit (please not that it is in bytes). You have to set the value according to your maximum file size e-g- 40MB(40000000 bytes).
2)- Script Time-out . Its default value is "00:01:30: which is 90 seconds. Increase it according to the time required by your code to run. I set it to 5 minutes and it solved the problem.