- Had to chnage the core API to add a destroy function pointer in
grpc_auth_metadata_processor.
- Tested end to end.
- Fixed some issues in the server_auth_filter (we were not checking the
length which put us at risk of an overflow).
- We always do the processing asynchronously but maintain a synchronous
API for the implementor of the processor.
- there are a lot of string copies right now. Having a StringPiece
object in grpc++ would really help with that (as we would use it for
C++ metadata).
- Please review the API carefully and if you're happy with it, I'll
proceed with tests.