AuraVPN/crates/aura-pki/tests/pki.rs

//! Integration tests for the Aura PKI: issuance, mutual-auth verification and
//! revocation.

use std::path::PathBuf;

use aura_pki::{AuraCa, AuraCertVerifier};
use rustls_pki_types::CertificateDer;
use uuid::Uuid;
use x509_parser::prelude::FromDer;

/// Decode the first CERTIFICATE block of a PEM string into owned DER.
fn pem_to_der(pem: &str) -> CertificateDer<'static> {
    let (_, item) =
        x509_parser::pem::parse_x509_pem(pem.as_bytes()).expect("issued cert is valid PEM");
    assert_eq!(item.label, "CERTIFICATE");
    CertificateDer::from(item.contents)
}

/// A unique temp path under the OS temp dir so parallel tests don't collide.
fn temp_path(suffix: &str) -> PathBuf {
    let mut p = std::env::temp_dir();
    p.push(format!("aura-pki-test-{}-{suffix}", Uuid::new_v4()));
    p
}

#[test]
fn test_ca_issue_server_cert() {
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let server = ca.issue_server_cert("vpn.example.com").unwrap();
    let chain = [pem_to_der(&server.cert_pem)];

    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();

    // Correct name verifies.
    verifier
        .verify_server_cert(&chain, "vpn.example.com")
        .expect("server cert should verify for its SAN");

    // Wrong name is rejected.
    let err = verifier.verify_server_cert(&chain, "evil.example.com");
    assert!(err.is_err(), "wrong server name must be rejected");
}

#[test]
fn test_ca_issue_client_cert() {
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let client = ca.issue_client_cert("alice").unwrap();
    let chain = [pem_to_der(&client.cert_pem)];

    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();
    let client_id = verifier
        .verify_client_cert(&chain)
        .expect("client cert should verify against its CA");
    assert_eq!(client_id, "alice");
}

#[test]
fn test_ca_issue_client_cert_uuid_cn() {
    // The spec notes client CNs are typically UUIDs; make sure that round-trips.
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let id = Uuid::new_v4().to_string();
    let client = ca.issue_client_cert(&id).unwrap();
    let chain = [pem_to_der(&client.cert_pem)];

    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();
    assert_eq!(verifier.verify_client_cert(&chain).unwrap(), id);
}

#[test]
fn test_invalid_cert_rejected() {
    // A leaf from an independent CA must not verify against the first CA.
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let rogue_ca = AuraCa::generate("Rogue CA").unwrap();

    let rogue_client = rogue_ca.issue_client_cert("mallory").unwrap();
    let rogue_server = rogue_ca.issue_server_cert("vpn.example.com").unwrap();
    let client_chain = [pem_to_der(&rogue_client.cert_pem)];
    let server_chain = [pem_to_der(&rogue_server.cert_pem)];

    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();

    assert!(
        verifier.verify_client_cert(&client_chain).is_err(),
        "client cert from a different CA must be rejected"
    );
    assert!(
        verifier
            .verify_server_cert(&server_chain, "vpn.example.com")
            .is_err(),
        "server cert from a different CA must be rejected"
    );
}

#[test]
fn test_revoked_cert_rejected() {
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let client = ca.issue_client_cert("bob").unwrap();
    let chain = [pem_to_der(&client.cert_pem)];

    let mut verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();

    // Before revocation: valid.
    assert_eq!(verifier.verify_client_cert(&chain).unwrap(), "bob");

    // Revoke by client id (Common Name) and confirm rejection.
    verifier.set_revoked(["bob".to_string()]);
    let err = verifier.verify_client_cert(&chain);
    assert!(err.is_err(), "revoked client id must be rejected");

    // Also exercise revoking by serial number (hex of the raw serial).
    let serial = {
        let der = pem_to_der(&client.cert_pem);
        let (_, parsed) =
            x509_parser::certificate::X509Certificate::from_der(der.as_ref()).unwrap();
        parsed
            .tbs_certificate
            .raw_serial()
            .iter()
            .map(|b| format!("{b:02x}"))
            .collect::<String>()
    };
    let mut verifier2 = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();
    verifier2.set_revoked([serial]);
    assert!(
        verifier2.verify_client_cert(&chain).is_err(),
        "revoked serial must be rejected"
    );
}

#[test]
fn test_save_load_roundtrip() {
    let cert_path = temp_path("ca.pem");
    let key_path = temp_path("ca.key");

    let original = AuraCa::generate("Aura Persisted CA").unwrap();
    original.save(&cert_path, &key_path).unwrap();

    let loaded = AuraCa::load(&cert_path, &key_path).unwrap();

    // The loaded CA presents the same anchor certificate...
    assert_eq!(original.ca_cert_pem(), loaded.ca_cert_pem());

    // ...and can still issue certs that verify against that anchor.
    let client = loaded.issue_client_cert("carol").unwrap();
    let chain = [pem_to_der(&client.cert_pem)];
    let verifier = AuraCertVerifier::new(&loaded.ca_cert_pem()).unwrap();
    assert_eq!(verifier.verify_client_cert(&chain).unwrap(), "carol");

    // A cert issued by the loaded CA also verifies against the ORIGINAL CA's
    // anchor (same key + subject), proving the identity survived the round-trip.
    let verifier_orig = AuraCertVerifier::new(&original.ca_cert_pem()).unwrap();
    assert_eq!(verifier_orig.verify_client_cert(&chain).unwrap(), "carol");

    let _ = std::fs::remove_file(&cert_path);
    let _ = std::fs::remove_file(&key_path);
}

#[test]
fn test_empty_chain_rejected() {
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();
    let empty: [CertificateDer; 0] = [];
    assert!(verifier.verify_client_cert(&empty).is_err());
    assert!(verifier
        .verify_server_cert(&empty, "vpn.example.com")
        .is_err());
}

#[test]
fn test_client_cert_not_valid_as_server_name() {
    // A client cert has no DNS SAN, so server-name verification must fail even
    // though the chain itself is trusted.
    let ca = AuraCa::generate("Aura Test CA").unwrap();
    let client = ca.issue_client_cert("dave").unwrap();
    let chain = [pem_to_der(&client.cert_pem)];
    let verifier = AuraCertVerifier::new(&ca.ca_cert_pem()).unwrap();
    assert!(verifier.verify_server_cert(&chain, "dave").is_err());
}