parlov-elicit 0.5.0

//! `EmgSchemaValidationPut` -- PUT schema validation order differential.
//!
//! Sends a malformed JSON body (`{"email":["invalid_type"]}`) via PUT.
//! If the server resolves the resource before validating the schema, an
//! existing resource returns a schema error while a nonexistent one returns
//! 404 or 201, revealing existence through validation order.

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

use super::MALFORMED_SCHEMA_BODY;
use crate::context::ScanContext;
use crate::strategy::Strategy;
use crate::types::{ProbeSpec, RiskLevel, StrategyMetadata};
use crate::util::{build_pair, clone_headers_static};

static METADATA: StrategyMetadata = StrategyMetadata {
    strategy_id: "emg-schema-validation-put",
    strategy_name: "EMG: PUT Schema Validation",
    risk: RiskLevel::MethodDestructive,
};

static TECHNIQUE: Technique = Technique {
    id: "emg-schema-validation-put",
    name: "PUT schema validation order 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 via PUT schema validation ordering.
pub struct EmgSchemaValidationPut;

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

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

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

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

    fn generate(&self, ctx: &ScanContext) -> Vec<ProbeSpec> {
        let headers = clone_headers_static(&ctx.headers, "content-type", "application/json");
        let body = Some(Bytes::from_static(MALFORMED_SCHEMA_BODY));
        let pair = build_pair(
            ctx,
            Method::PUT,
            headers.clone(),
            headers,
            body,
            METADATA.clone(),
            TECHNIQUE,
        );
        vec![ProbeSpec::Pair(pair)]
    }
}

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

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

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

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

    #[test]
    fn risk_is_method_destructive() {
        assert_eq!(EmgSchemaValidationPut.risk(), RiskLevel::MethodDestructive);
    }

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

    #[test]
    fn has_content_type_json() {
        let specs = EmgSchemaValidationPut.generate(&ctx_method_destructive());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair variant")
        };
        assert_eq!(
            pair.baseline.headers.get("content-type").unwrap(),
            "application/json"
        );
        assert_eq!(
            pair.probe.headers.get("content-type").unwrap(),
            "application/json"
        );
    }

    #[test]
    fn has_malformed_body() {
        let specs = EmgSchemaValidationPut.generate(&ctx_method_destructive());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair variant")
        };
        let body = pair.baseline.body.as_ref().expect("body must be present");
        let text = std::str::from_utf8(body).expect("body must be valid UTF-8");
        assert!(text.contains("email"), "body must contain 'email': {text}");
    }
}