C++ URI validation in Envoy

[asraa]

Looks like Envoy is using C++ URI validations in StsService: https://github.com/envoyproxy/envoy/blob/062c895f499382ae61dead16db2a7e78b9146525/api/envoy/api/v2/core/grpc_service.proto#L94

Config validations throw an unimplemented exception when initializing the server (rather than a controlled a ProtoValidation error). https://oss-fuzz.com/testcase-detail/5665272556158976

It might be a good time to implement this constraint. I think less new logic in PGV is better, and I wonder if it's best to use a regex with RE2 to implement the constraint, or a small C++ library (but not ideal, as it's a dependency)

@JimmyCYJ

[JimmyCYJ]

@asraa Thanks for letting me know. I just hit the same issue when I start to set up integration test today.

[nareddyt]

Thanks for posting this issue @asraa, we also ran into the same issue. Would love to see this implemented, even if it's a regex check. Would be very helpful for config validation.