8. Procedure – Disabling delta encoding

Purpose: 

Delta encoding (RFC 3229) is used for updating a previously downloaded file. It enables to download only those parts of the file that were modified. This technique is also problematic, because the complete file is not available for the virus filter. Similarly to byteranges, this can also be disabled.

The client sends an A-IM header to the server if it can accept delta-encoded responses. To disable delta encoding, it is sufficient to remove these headers from the client requests.Complete the following steps.

Steps: 

1. Select Zorp > Proxies, then select the HttpVirusProxy proxy class.

2. Add the self.request_header attribute to the Changed config attributes panel.

3. Select this new attribute, then click Edit > New.

4. Enter A-IM, then click OK.

5. Click on the text in the Type field, then select const_http_hdr_drop.

   Python:

   self.request_header["A-IM"] = (HTTP_HDR_DROP)