Publish SlashReport onto the Tributary

coordinator/src/main.rs

@@ -17,7 +17,7 @@ use message_queue::{Service, client::MessageQueue};
 use serai_task::{Task, TaskHandle, ContinuallyRan};
 
 use serai_cosign::{SignedCosign, Cosigning};
-use serai_coordinator_substrate::{CanonicalEventStream, EphemeralEventStream};
+use serai_coordinator_substrate::{CanonicalEventStream, EphemeralEventStream, SignSlashReport};
 use serai_coordinator_tributary::Transaction;
 
 mod db;
@@ -148,6 +148,8 @@ async fn main() {
       prune_tributary_db(to_cleanup);
       // Drain the cosign intents created for this set
       while !Cosigning::<Db>::intended_cosigns(&mut txn, to_cleanup).is_empty() {}
+      // Remove the SignSlashReport notification
+      SignSlashReport::try_recv(&mut txn, to_cleanup);
     }
 
     // Remove retired Tributaries from ActiveTributaries
@@ -198,7 +200,6 @@ async fn main() {
   };
 
   // Spawn the Substrate scanners
-  // TODO: SignSlashReport
   let (substrate_task_def, substrate_task) = Task::new();
   let (substrate_canonical_task_def, substrate_canonical_task) = Task::new();
   tokio::spawn(

coordinator/src/tributary.rs

@@ -2,6 +2,7 @@ use core::{future::Future, time::Duration};
 use std::sync::Arc;
 
 use zeroize::Zeroizing;
+use rand_core::OsRng;
 use blake2::{digest::typenum::U32, Digest, Blake2s};
 use ciphersuite::{Ciphersuite, Ristretto};
 
@@ -12,14 +13,14 @@ use serai_db::{DbTxn, Db as DbTrait};
 use scale::Encode;
 use serai_client::validator_sets::primitives::ValidatorSet;
 
-use tributary_sdk::{ProvidedError, Tributary};
+use tributary_sdk::{TransactionError, ProvidedError, Tributary};
 
 use serai_task::{Task, TaskHandle, ContinuallyRan};
 
 use message_queue::{Service, Metadata, client::MessageQueue};
 
 use serai_cosign::Cosigning;
-use serai_coordinator_substrate::NewSetInformation;
+use serai_coordinator_substrate::{NewSetInformation, SignSlashReport};
 use serai_coordinator_tributary::{Transaction, ProcessorMessages, ScanTributaryTask};
 use serai_coordinator_p2p::P2p;
 
@@ -27,9 +28,9 @@ use crate::Db;
 
 /// Provides Cosign/Cosigned Transactions onto the Tributary.
 pub(crate) struct ProvideCosignCosignedTransactionsTask<CD: DbTrait, TD: DbTrait, P: P2p> {
-  pub(crate) db: CD,
-  pub(crate) set: NewSetInformation,
-  pub(crate) tributary: Tributary<TD, Transaction, P>,
+  db: CD,
+  set: NewSetInformation,
+  tributary: Tributary<TD, Transaction, P>,
 }
 impl<CD: DbTrait, TD: DbTrait, P: P2p> ContinuallyRan
   for ProvideCosignCosignedTransactionsTask<CD, TD, P>
@@ -128,9 +129,9 @@ impl<CD: DbTrait, TD: DbTrait, P: P2p> ContinuallyRan
 
 /// Takes the messages from ScanTributaryTask and publishes them to the message-queue.
 pub(crate) struct TributaryProcessorMessagesTask<TD: DbTrait> {
-  pub(crate) tributary_db: TD,
-  pub(crate) set: ValidatorSet,
-  pub(crate) message_queue: Arc<MessageQueue>,
+  tributary_db: TD,
+  set: ValidatorSet,
+  message_queue: Arc<MessageQueue>,
 }
 impl<TD: DbTrait> ContinuallyRan for TributaryProcessorMessagesTask<TD> {
   fn run_iteration(&mut self) -> impl Send + Future<Output = Result<bool, String>> {
@@ -155,6 +156,51 @@ impl<TD: DbTrait> ContinuallyRan for TributaryProcessorMessagesTask<TD> {
   }
 }
 
+/// Checks for the notification to sign a slash report and does so if present.
+pub(crate) struct SignSlashReportTask<CD: DbTrait, TD: DbTrait, P: P2p> {
+  db: CD,
+  tributary_db: TD,
+  tributary: Tributary<TD, Transaction, P>,
+  set: NewSetInformation,
+  key: Zeroizing<<Ristretto as Ciphersuite>::F>,
+}
+impl<CD: DbTrait, TD: DbTrait, P: P2p> ContinuallyRan for SignSlashReportTask<CD, TD, P> {
+  fn run_iteration(&mut self) -> impl Send + Future<Output = Result<bool, String>> {
+    async move {
+      let mut txn = self.db.txn();
+      let Some(()) = SignSlashReport::try_recv(&mut txn, self.set.set) else { return Ok(false) };
+
+      // Fetch the slash report for this Tributary
+      let mut tx =
+        serai_coordinator_tributary::slash_report_transaction(&self.tributary_db, &self.set);
+      tx.sign(&mut OsRng, self.tributary.genesis(), &self.key);
+
+      let res = self.tributary.add_transaction(tx.clone()).await;
+      match &res {
+        // Fresh publication, already published
+        Ok(true | false) => {}
+        Err(
+          TransactionError::TooLargeTransaction |
+          TransactionError::InvalidSigner |
+          TransactionError::InvalidNonce |
+          TransactionError::InvalidSignature |
+          TransactionError::InvalidContent,
+        ) => {
+          panic!("created an invalid SlashReport transaction, tx: {tx:?}, err: {res:?}");
+        }
+        // We've published too many transactions recently
+        // Drop this txn to try to publish it again later on a future iteration
+        Err(TransactionError::TooManyInMempool) => return Ok(false),
+        // This isn't a Provided transaction so this should never be hit
+        Err(TransactionError::ProvidedAddedToMempool) => unreachable!(),
+      }
+
+      txn.commit();
+      Ok(true)
+    }
+  }
+}
+
 /// Run the scan task whenever the Tributary adds a new block.
 async fn scan_on_new_block<CD: DbTrait, TD: DbTrait, P: P2p>(
   db: CD,
@@ -183,8 +229,14 @@ async fn scan_on_new_block<CD: DbTrait, TD: DbTrait, P: P2p>(
 
 /// Spawn a Tributary.
 ///
-/// This will spawn the Tributary, the Tributary scan task, forward the messages from the scan task
-/// to the message queue, provide Cosign/Cosigned transactions, and inform the P2P network.
+/// This will:
+/// - Spawn the Tributary
+/// - Inform the P2P network of the Tributary
+/// - Spawn the ScanTributaryTask
+/// - Spawn the ProvideCosignCosignedTransactionsTask
+/// - Spawn the TributaryProcessorMessagesTask
+/// - Spawn the SignSlashReportTask
+/// - Iterate the scan task whenever a new block occurs (not just on the standard interval)
 pub(crate) async fn spawn_tributary<P: P2p>(
   db: Db,
   message_queue: Arc<MessageQueue>,
@@ -219,8 +271,14 @@ pub(crate) async fn spawn_tributary<P: P2p>(
 
   // Spawn the Tributary
   let tributary_db = crate::db::tributary_db(set.set);
-  let tributary =
-    Tributary::new(tributary_db.clone(), genesis, start_time, serai_key, tributary_validators, p2p)
+  let tributary = Tributary::new(
+    tributary_db.clone(),
+    genesis,
+    start_time,
+    serai_key.clone(),
+    tributary_validators,
+    p2p,
+  )
   .await
   .unwrap();
   let reader = tributary.reader();
@@ -256,12 +314,25 @@ pub(crate) async fn spawn_tributary<P: P2p>(
   // Spawn the scan task
   let (scan_tributary_task_def, scan_tributary_task) = Task::new();
   tokio::spawn(
-    ScanTributaryTask::<_, _, P>::new(db.clone(), tributary_db, &set, reader)
+    ScanTributaryTask::<_, _, P>::new(db.clone(), tributary_db.clone(), &set, reader)
       // This is the only handle for this TributaryProcessorMessagesTask, so when this task is
       // dropped, it will be too
       .continually_run(scan_tributary_task_def, vec![scan_tributary_messages_task]),
   );
 
+  // Spawn the sign slash report task
+  let (sign_slash_report_task_def, sign_slash_report_task) = Task::new();
+  tokio::spawn(
+    (SignSlashReportTask {
+      db: db.clone(),
+      tributary_db,
+      tributary: tributary.clone(),
+      set: set.clone(),
+      key: serai_key,
+    })
+    .continually_run(sign_slash_report_task_def, vec![]),
+  );
+
   // Whenever a new block occurs, immediately run the scan task
   // This function also preserves the ProvideCosignCosignedTransactionsTask handle until the
   // Tributary is retired, ensuring it isn't dropped prematurely and that the task don't run ad
@@ -271,6 +342,6 @@ pub(crate) async fn spawn_tributary<P: P2p>(
     set.set,
     tributary,
     scan_tributary_task,
-    vec![provide_cosign_cosigned_transactions_task],
+    vec![provide_cosign_cosigned_transactions_task, sign_slash_report_task],
   ));
 }

coordinator/substrate/src/ephemeral.rs

@@ -234,7 +234,7 @@ impl<D: Db> ContinuallyRan for EphemeralEventStream<D> {
           else {
             panic!("AcceptedHandover event wasn't a AcceptedHandover event: {accepted_handover:?}");
           };
-          crate::SignSlashReport::send(&mut txn, set);
+          crate::SignSlashReport::send(&mut txn, *set);
         }
 
         txn.commit();

coordinator/substrate/src/lib.rs

@@ -66,8 +66,8 @@ mod _public_db {
 
       // Relevant new set, from an ephemeral event stream
       NewSet: () -> NewSetInformation,
-      // Relevant sign slash report, from an ephemeral event stream
-      SignSlashReport: () -> ValidatorSet,
+      // Potentially relevant sign slash report, from an ephemeral event stream
+      SignSlashReport: (set: ValidatorSet) -> (),
     }
   );
 }
@@ -109,12 +109,12 @@ impl NewSet {
 /// notifications for all relevant validator sets will be included.
 pub struct SignSlashReport;
 impl SignSlashReport {
-  pub(crate) fn send(txn: &mut impl DbTxn, set: &ValidatorSet) {
-    _public_db::SignSlashReport::send(txn, set);
+  pub(crate) fn send(txn: &mut impl DbTxn, set: ValidatorSet) {
+    _public_db::SignSlashReport::send(txn, set, &());
   }
   /// Try to receive a notification to sign a slash report, returning `None` if there is none to
   /// receive.
-  pub fn try_recv(txn: &mut impl DbTxn) -> Option<ValidatorSet> {
-    _public_db::SignSlashReport::try_recv(txn)
+  pub fn try_recv(txn: &mut impl DbTxn, set: ValidatorSet) -> Option<()> {
+    _public_db::SignSlashReport::try_recv(txn, set)
   }
 }

coordinator/tributary/src/db.rs

@@ -184,8 +184,8 @@ create_db!(
     // The last handled tributary block's (number, hash)
     LastHandledTributaryBlock: (set: ValidatorSet) -> (u64, [u8; 32]),
 
-    // The slash points a validator has accrued, with u64::MAX representing a fatal slash.
-    SlashPoints: (set: ValidatorSet, validator: SeraiAddress) -> u64,
+    // The slash points a validator has accrued, with u32::MAX representing a fatal slash.
+    SlashPoints: (set: ValidatorSet, validator: SeraiAddress) -> u32,
 
     // The latest Substrate block to cosign.
     LatestSubstrateBlockToCosign: (set: ValidatorSet) -> [u8; 32],
@@ -316,7 +316,7 @@ impl TributaryDb {
     reason: &str,
   ) {
     log::warn!("{validator} fatally slashed: {reason}");
-    SlashPoints::set(txn, set, validator, &u64::MAX);
+    SlashPoints::set(txn, set, validator, &u32::MAX);
   }
 
   pub(crate) fn is_fatally_slashed(
@@ -324,7 +324,7 @@ impl TributaryDb {
     set: ValidatorSet,
     validator: SeraiAddress,
   ) -> bool {
-    SlashPoints::get(getter, set, validator).unwrap_or(0) == u64::MAX
+    SlashPoints::get(getter, set, validator).unwrap_or(0) == u32::MAX
   }
 
   #[allow(clippy::too_many_arguments)]

coordinator/tributary/src/lib.rs

@@ -511,3 +511,13 @@ impl<CD: Db, TD: Db, P: P2p> ContinuallyRan for ScanTributaryTask<CD, TD, P> {
     }
   }
 }
+
+/// Create the Transaction::SlashReport to publish per the local view.
+pub fn slash_report_transaction(getter: &impl Get, set: &NewSetInformation) -> Transaction {
+  let mut slash_points = Vec::with_capacity(set.validators.len());
+  for (validator, _weight) in set.validators.iter().copied() {
+    let validator = SeraiAddress::from(validator);
+    slash_points.push(SlashPoints::get(getter, set.set, validator).unwrap_or(0));
+  }
+  Transaction::SlashReport { slash_points, signed: Signed::default() }
+}

coordinator/tributary/src/transaction.rs

@@ -6,7 +6,7 @@ use rand_core::{RngCore, CryptoRng};
 
 use blake2::{digest::typenum::U32, Digest, Blake2b};
 use ciphersuite::{
-  group::{ff::Field, GroupEncoding},
+  group::{ff::Field, Group, GroupEncoding},
   Ciphersuite, Ristretto,
 };
 use schnorr::SchnorrSignature;
@@ -80,6 +80,18 @@ impl Signed {
   }
 }
 
+impl Default for Signed {
+  fn default() -> Self {
+    Self {
+      signer: <Ristretto as Ciphersuite>::G::identity(),
+      signature: SchnorrSignature {
+        R: <Ristretto as Ciphersuite>::G::identity(),
+        s: <Ristretto as Ciphersuite>::F::ZERO,
+      },
+    }
+  }
+}
+
 /// The Tributary transaction definition used by Serai
 #[derive(Clone, PartialEq, Eq, Debug, BorshSerialize, BorshDeserialize)]
 pub enum Transaction {