http_random_auth.rs

use envoy_proxy_dynamic_modules_rust_sdk::*;
use rand::prelude::*;

/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilterConfig`] trait.
///
/// The trait corresponds to a Envoy filter chain configuration.
pub struct FilterConfig {}

impl FilterConfig {
    /// This is the constructor for the [`FilterConfig`].
    ///
    /// filter_config is the filter config from the Envoy config here:
    /// https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/dynamic_modules/v3/dynamic_modules.proto#envoy-v3-api-msg-extensions-dynamic-modules-v3-dynamicmoduleconfig
    pub fn new(_filter_config: &str) -> Self {
        Self {}
    }
}

impl<EHF: EnvoyHttpFilter> HttpFilterConfig<EHF> for FilterConfig {
    /// This is called for each new HTTP filter.
    fn new_http_filter(&mut self, _envoy: &mut EHF) -> Box<dyn HttpFilter<EHF>> {
        Box::new(Filter {})
    }
}

/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilter`] trait.
///
/// This is a passthrough filter that randomly rejects requests.
pub struct Filter {}

/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilter`] trait.
impl<EHF: EnvoyHttpFilter> HttpFilter<EHF> for Filter {
    fn on_request_headers(
        &mut self,
        envoy_filter: &mut EHF,
        _end_of_stream: bool,
    ) -> abi::envoy_dynamic_module_type_on_http_filter_request_headers_status {
        let reject = rand::rng().random::<bool>();
        if reject {
            envoy_filter.send_response(403, vec![], Some(b"Access forbidden"));
            return abi::envoy_dynamic_module_type_on_http_filter_request_headers_status::StopIteration;
        }
        abi::envoy_dynamic_module_type_on_http_filter_request_headers_status::Continue
    }
}