parlov-elicit 0.5.0

//! `EmgAppVsServer404` -- application vs server 404 body differential.
//!
//! Compares an application-routed 404 (structured JSON with request metadata)
//! against the server's default 404 (plain text, no app headers). The baseline
//! hits the real route with a known-existing ID; the probe hits a garbled URL
//! that bypasses application routing entirely.

use http::Method;
use parlov_core::{
    always_applicable, NormativeStrength, OracleClass, ProbeDefinition, SignalSurface, Technique,
    Vector,
};

use crate::context::ScanContext;
use crate::strategy::Strategy;
use crate::types::{ProbePair, ProbeSpec, RiskLevel, StrategyMetadata};
use crate::util::{garble_path_segment, substitute_url};

static METADATA: StrategyMetadata = StrategyMetadata {
    strategy_id: "emg-app-vs-server-404",
    strategy_name: "EMG: App vs Server 404",
    risk: RiskLevel::Safe,
};

static TECHNIQUE: Technique = Technique {
    id: "emg-app-vs-server-404",
    name: "Application vs server 404 body differential",
    oracle_class: OracleClass::Existence,
    vector: Vector::ErrorMessageGranularity,
    strength: NormativeStrength::May,
    normalization_weight: None,
    inverted_signal_weight: None,
    method_relevant: false,
    parser_relevant: false,
    applicability: always_applicable,
    contradiction_surface: SignalSurface::Body,
};

/// Elicits existence differentials by comparing app-routed vs server-default 404 bodies.
pub struct EmgAppVsServer404;

impl Strategy for EmgAppVsServer404 {
    fn metadata(&self) -> &'static StrategyMetadata {
        &METADATA
    }

    fn technique_def(&self) -> &'static Technique {
        &TECHNIQUE
    }

    fn methods(&self) -> &[Method] {
        &[Method::GET]
    }

    fn is_applicable(&self, _ctx: &ScanContext) -> bool {
        true
    }

    fn generate(&self, ctx: &ScanContext) -> Vec<ProbeSpec> {
        let baseline_url = substitute_url(&ctx.target, &ctx.baseline_id);
        let probe_url = garble_path_segment(&ctx.target);

        let pair = ProbePair {
            baseline: ProbeDefinition {
                url: baseline_url,
                method: Method::GET,
                headers: ctx.headers.clone(),
                body: None,
            },
            probe: ProbeDefinition {
                url: probe_url,
                method: Method::GET,
                headers: ctx.headers.clone(),
                body: None,
            },
            canonical_baseline: None,
            metadata: METADATA.clone(),
            technique: TECHNIQUE,
            chain_provenance: None,
        };
        vec![ProbeSpec::Pair(pair)]
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_utils::minimal_ctx;

    fn make_ctx() -> ScanContext {
        ScanContext {
            target: "https://api.example.com/api/users/{id}".to_owned(),
            ..minimal_ctx()
        }
    }

    #[test]
    fn generates_correct_technique_vector() {
        let specs = EmgAppVsServer404.generate(&make_ctx());
        assert_eq!(specs[0].technique().vector, Vector::ErrorMessageGranularity);
    }

    #[test]
    fn generates_correct_technique_strength() {
        let specs = EmgAppVsServer404.generate(&make_ctx());
        assert_eq!(specs[0].technique().strength, NormativeStrength::May);
    }

    #[test]
    fn is_always_applicable() {
        assert!(EmgAppVsServer404.is_applicable(&make_ctx()));
    }

    #[test]
    fn risk_is_safe() {
        assert_eq!(EmgAppVsServer404.risk(), RiskLevel::Safe);
    }

    #[test]
    fn generates_get_method() {
        let specs = EmgAppVsServer404.generate(&make_ctx());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair variant")
        };
        assert_eq!(pair.baseline.method, Method::GET);
        assert_eq!(pair.probe.method, Method::GET);
    }

    #[test]
    fn baseline_url_has_baseline_id() {
        let specs = EmgAppVsServer404.generate(&make_ctx());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair variant")
        };
        assert!(
            pair.baseline.url.contains("1001"),
            "baseline URL must contain baseline_id: {}",
            pair.baseline.url
        );
    }

    #[test]
    fn probe_url_is_garbled() {
        let specs = EmgAppVsServer404.generate(&make_ctx());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair variant")
        };
        assert!(
            !pair.probe.url.contains("{id}"),
            "probe URL must not contain {{id}}: {}",
            pair.probe.url
        );
        assert!(
            pair.probe.url.contains("_parlov_no_route"),
            "probe URL must contain _parlov_no_route: {}",
            pair.probe.url
        );
    }

    #[test]
    fn garble_replaces_parent_segment() {
        let result = garble_path_segment("https://api.example.com/api/users/{id}");
        assert_eq!(result, "https://api.example.com/api/_parlov_no_route/0");
    }

    #[test]
    fn garble_fallback_when_single_segment() {
        let result = garble_path_segment("https://api.example.com/{id}");
        assert_eq!(result, "https://api.example.com/_parlov_no_route");
    }
}