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//! Entry point of a Tor relay that is the [`TorRelay`] objects
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use std::sync::Arc;
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use tor_chanmgr::Dormancy;
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use tor_config_path::CfgPathResolver;
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use tor_error::internal;
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use tor_keymgr::{
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    ArtiEphemeralKeystore, ArtiNativeKeystore, KeyMgr, KeyMgrBuilder, KeystoreSelector,
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};
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use tor_memquota::ArcMemoryQuotaTrackerExt as _;
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use tor_netdir::params::NetParameters;
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use tor_proto::memquota::ToplevelAccount;
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use tor_relay_crypto::pk::{RelayIdentityKeypair, RelayIdentityKeypairSpecifier};
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use tor_rtcompat::Runtime;
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use tracing::info;
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use crate::config::TorRelayConfig;
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use crate::err::ErrorDetail;
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/// Represent an active Relay on the Tor network.
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#[derive(Clone)]
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pub(crate) struct TorRelay<R: Runtime> {
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    /// Asynchronous runtime object.
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    #[allow(unused)] // TODO RELAY remove
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    runtime: R,
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    /// Path resolver for expanding variables in [`CfgPath`](tor_config_path::CfgPath)s.
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    #[allow(unused)] // TODO RELAY remove
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    path_resolver: CfgPathResolver,
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    /// Channel manager, used by circuits etc.,
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    #[allow(unused)] // TODO RELAY remove
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    chanmgr: Arc<tor_chanmgr::ChanMgr<R>>,
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    /// Key manager holding all relay keys and certificates.
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    #[allow(unused)] // TODO RELAY remove
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    keymgr: Arc<KeyMgr>,
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}
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impl<R: Runtime> TorRelay<R> {
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    /// Create a new Tor relay with the given [runtime][tor_rtcompat] and configuration.
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    pub(crate) fn new(
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        runtime: R,
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        config: &TorRelayConfig,
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        path_resolver: CfgPathResolver,
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    ) -> Result<Self, ErrorDetail> {
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        let keymgr = Self::create_keymgr(config, &path_resolver)?;
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        let chanmgr = Arc::new(tor_chanmgr::ChanMgr::new(
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            runtime.clone(),
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            &config.channel,
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            Dormancy::Active,
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            &NetParameters::default(),
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            ToplevelAccount::new_noop(), // TODO RELAY get mq from TorRelay
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        ));
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        Ok(Self {
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            runtime,
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            path_resolver,
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            chanmgr,
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            keymgr,
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        })
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    }
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    /// Create the [key manager](KeyMgr).
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    fn create_keymgr(
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        config: &TorRelayConfig,
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        path_resolver: &CfgPathResolver,
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    ) -> Result<Arc<KeyMgr>, ErrorDetail> {
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        let key_store_dir = config.storage.keystore_dir(path_resolver)?;
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        let permissions = config.storage.permissions();
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        // Store for the short-term keys that we don't need to keep on disk. The store identifier
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        // is relay explicit because it can be used in other crates for channel and circuit.
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        let ephemeral_store = ArtiEphemeralKeystore::new("relay-ephemeral".into());
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        let persistent_store =
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            ArtiNativeKeystore::from_path_and_mistrust(&key_store_dir, permissions)?;
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        info!("Using relay keystore from {key_store_dir:?}");
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        let keymgr = Arc::new(
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            KeyMgrBuilder::default()
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                .primary_store(Box::new(persistent_store))
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                .set_secondary_stores(vec![Box::new(ephemeral_store)])
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                .build()
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                .map_err(|e| internal!("Failed to build KeyMgr: {e}"))?,
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        );
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        // Attempt to generate any missing keys/cert from the KeyMgr.
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        Self::try_generate_keys(&keymgr)?;
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        Ok(keymgr)
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    }
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    /// Generate the relay keys.
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    fn try_generate_keys(keymgr: &KeyMgr) -> Result<(), ErrorDetail> {
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        let mut rng = tor_llcrypto::rng::CautiousRng;
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        // Attempt to get the relay long-term identity key from the key manager. If not present,
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        // generate it. We need this key to sign the signing certificates.
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        let _kp_relay_id = keymgr.get_or_generate::<RelayIdentityKeypair>(
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            &RelayIdentityKeypairSpecifier::new(),
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            KeystoreSelector::default(),
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            &mut rng,
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        )?;
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        // TODO: Once certificate supports is added to the KeyMgr, we need to get/gen the
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        // RelaySigning (KP_relaysign_ed) certs from the native persistent store.
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        //
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        // If present, rotate it if expired. Else, generate it. Rotation or creation require the
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        // relay identity keypair (above) in order to sign the RelaySigning.
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        //
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        // We then need to generate the RelayLink (KP_link_ed) certificate which is in turn signed
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        // by the RelaySigning cert.
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        Ok(())
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    }
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}