This article applies to all MetaDefender ICAP Server releases deployed on Windows and Linux systems.
Issue:
Files are being blocked by the MetaDefender ICAP Server with the error message “Decoding content encoded failed.”
This occurs when the ICAP Server is unable to decode the Base64-encoded payload contained in the HTTP request body. This is often due to a misconfiguration in the Node Selector in the ICAP workflow, preventing the correct extraction of Base64 data from the JSON payload, specifically from the intended key.
Prevention:
To prevent this issue, consider the following:
- Double-check the Node Selector configuration to ensure it correctly decodes Base64 data from the JSON payload.
- Verify that the Node Selector's value actually contains Base64 data.
- Check for conflicts if multiple Node Selectors are configured in one workflow.
Example:
Consider the following JSON payloads:
- Payload 1:
{ "Content": "<base64 data>", "Name": "document.pdf"}- Payload 2:
{ "Name": "<base64 data>" }
{ "Name": "<base64 data>"}The correct Node Selector for extracting the Base64 encoded file content in Payload 1 is /Content, with the node for the file name being /Name. However, if another Node Selector is also configured to specify /Name as the Base64 content to scan for the Payload 2 within the same ICAP workflow, a conflict arises.
In this case, the Name key in Payload 1 does not contain Base64 encoded data, resulting in a decoding error because the system attempts to perform Base64 decoding on non-Base64 encoded content (the Payload 2 Node Selector).
Resolution:
In the above example, if a conflict exists with Node Selector configurations, it is best to split the workflow into two separate workflows.
- Use request filters to match the corresponding Node Selector and requests containing JSON payloads for each workflow.
If Further Assistance is required, please proceed to log a support case or chat with our support engineer.
