When using Poco::Net http classes in situations with Amazon S3 or similar authentication the client (not Poco) creates a signature from HTTP headers before sensing the request to the server. Some of the header values can be RFC2047 encoded at that point.

Verification of the signature implemented with a Poco based HTTP service fails because RFC2047 decoding is performed automatically (#1121) before the custom request handler receives the HTTP request.

Some kind interface shall be provided to be able to access the original HTTP headers when needed.

Proposal:

• add option to disable automatic conversion (default is on)
• add a function to perform the conversion manually