String matcher max length field

[jh125486]

Title: Add a max length field to String Matcher

Description:

Currently we use a regex to limit the max header length, but a simpler "max length" field would reduce the need for initializing the RegexMatcher.

Protobuf in question: string.proto

[kyessenov]

+1 sounds like a good idea to me. Another place to add this could be in https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/http/header_validators. If the motivation is to reduce overall header data, it might be better to enforce that at the protocol level.

[jh125486]

+1 sounds like a good idea to me. Another place to add this could be in https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/http/header_validators. If the motivation is to reduce overall header data, it might be better to enforce that at the protocol level.

We're specifically trying to limit the length of XFF headers to avoid infinite forwarding loops by returning a 431, so maybe?

[jh125486]

@kyessenov should I create a PR for the string.proto or https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/http/header_validators/envoy_default/v3/header_validator.proto#extensions-http-header-validators-envoy-default-v3-headervalidatorconfig?