Finish binding Tendermint, bar the P2P layer

coordinator/tributary/Cargo.toml

@@ -21,8 +21,14 @@ transcript = { package = "flexible-transcript", path = "../../crypto/transcript"
 ciphersuite = { package = "ciphersuite", path = "../../crypto/ciphersuite", features = ["ristretto"] }
 schnorr = { package = "schnorr-signatures", path = "../../crypto/schnorr" }
 
+hex = "0.4"
+log = "0.4"
+
+scale = { package = "parity-scale-codec", version = "3", features = ["derive"] }
 tendermint = { package = "tendermint-machine", path = "./tendermint" }
 
+tokio = { version = "1", features = ["macros", "sync", "time", "rt"] }
+
 [dev-dependencies]
 zeroize = "^1.5"
 rand_core = "0.6"

coordinator/tributary/src/block.rs

@@ -48,7 +48,7 @@ impl ReadWrite for BlockHeader {
 }
 
 impl BlockHeader {
-  fn hash(&self) -> [u8; 32] {
+  pub fn hash(&self) -> [u8; 32] {
     Blake2s256::digest([b"tributary_block".as_ref(), &self.serialize()].concat()).into()
   }
 }

coordinator/tributary/src/blockchain.rs

@@ -55,12 +55,8 @@ impl<T: Transaction> Blockchain<T> {
   }
 
   /// Add a block.
-  #[must_use]
-  pub fn add_block(&mut self, block: &Block<T>) -> bool {
-    // TODO: Handle desyncs re: provided transactions properly
-    if self.verify_block(block).is_err() {
-      return false;
-    }
+  pub fn add_block(&mut self, block: &Block<T>) -> Result<(), BlockError> {
+    self.verify_block(block)?;
 
     // None of the following assertions should be reachable since we verified the block
     self.tip = block.hash();
@@ -85,6 +81,6 @@ impl<T: Transaction> Blockchain<T> {
       }
     }
 
-    true
+    Ok(())
   }
 }

coordinator/tributary/src/tendermint.rs

@@ -1,4 +1,7 @@
 use core::ops::Deref;
+use std::{sync::Arc, collections::HashMap};
+
+use async_trait::async_trait;
 
 use subtle::ConstantTimeEq;
 use zeroize::{Zeroize, Zeroizing};
@@ -14,7 +17,18 @@ use ciphersuite::{
 };
 use schnorr::SchnorrSignature;
 
-use tendermint::ext::{Signer as SignerTrait, SignatureScheme as SignatureSchemeTrait};
+use scale::{Encode, Decode};
+use tendermint::{
+  SignedMessageFor,
+  ext::{
+    BlockNumber, RoundNumber, Signer as SignerTrait, SignatureScheme, Weights, Block as BlockTrait,
+    BlockError as TendermintBlockError, Commit, Network as NetworkTrait,
+  },
+};
+
+use tokio::time::{Duration, sleep};
+
+use crate::{ReadWrite, Transaction, TransactionError, BlockHeader, Block, BlockError, Blockchain};
 
 fn challenge(
   genesis: [u8; 32],
@@ -37,7 +51,7 @@ struct Signer {
   key: Zeroizing<<Ristretto as Ciphersuite>::F>,
 }
 
-#[async_trait::async_trait]
+#[async_trait]
 impl SignerTrait for Signer {
   type ValidatorId = [u8; 32];
   type Signature = [u8; 64];
@@ -85,19 +99,25 @@ impl SignerTrait for Signer {
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
-struct SignatureScheme {
+struct Validators {
   genesis: [u8; 32],
+  weight: u64,
+  weights: HashMap<[u8; 32], u64>,
+  robin: Vec<[u8; 32]>,
 }
 
-impl SignatureSchemeTrait for SignatureScheme {
+impl SignatureScheme for Validators {
   type ValidatorId = [u8; 32];
   type Signature = [u8; 64];
   // TODO: Use half-aggregation.
   type AggregateSignature = Vec<[u8; 64]>;
-  type Signer = Signer;
+  type Signer = Arc<Signer>;
 
   #[must_use]
   fn verify(&self, validator: Self::ValidatorId, msg: &[u8], sig: &Self::Signature) -> bool {
+    if !self.weights.contains_key(&validator) {
+      return false;
+    }
     let Ok(validator_point) = Ristretto::read_G::<&[u8]>(&mut validator.as_ref()) else {
       return false;
     };
@@ -126,3 +146,122 @@ impl SignatureSchemeTrait for SignatureScheme {
     true
   }
 }
+
+impl Weights for Validators {
+  type ValidatorId = [u8; 32];
+
+  fn total_weight(&self) -> u64 {
+    self.weight
+  }
+  fn weight(&self, validator: Self::ValidatorId) -> u64 {
+    self.weights[&validator]
+  }
+  fn proposer(&self, block: BlockNumber, round: RoundNumber) -> Self::ValidatorId {
+    let block = usize::try_from(block.0).unwrap();
+    let round = usize::try_from(round.0).unwrap();
+    // If multiple rounds are used, a naive block + round would cause the same index to be chosen
+    // in quick succesion.
+    // Accordingly, if we use additional rounds, jump halfway around.
+    // While this is still game-able, it's not explicitly reusing indexes immediately after each
+    // other.
+    self.robin
+      [(block + (if round == 0 { 0 } else { round + (self.robin.len() / 2) })) % self.robin.len()]
+  }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug, Encode, Decode)]
+struct TendermintBlock(Vec<u8>);
+impl BlockTrait for TendermintBlock {
+  type Id = [u8; 32];
+  fn id(&self) -> Self::Id {
+    BlockHeader::read::<&[u8]>(&mut self.0.as_ref()).unwrap().hash()
+  }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+struct Network<T: Transaction> {
+  genesis: [u8; 32],
+  signer: Arc<Signer>,
+  validators: Arc<Validators>,
+  blockchain: Blockchain<T>,
+}
+
+#[async_trait]
+impl<T: Transaction> NetworkTrait for Network<T> {
+  type ValidatorId = [u8; 32];
+  type SignatureScheme = Arc<Validators>;
+  type Weights = Arc<Validators>;
+  type Block = TendermintBlock;
+
+  const BLOCK_PROCESSING_TIME: u32 = 3;
+  const LATENCY_TIME: u32 = 1;
+
+  fn signer(&self) -> Arc<Signer> {
+    self.signer.clone()
+  }
+  fn signature_scheme(&self) -> Arc<Validators> {
+    self.validators.clone()
+  }
+  fn weights(&self) -> Arc<Validators> {
+    self.validators.clone()
+  }
+
+  async fn broadcast(&mut self, _msg: SignedMessageFor<Self>) {
+    todo!()
+  }
+  async fn slash(&mut self, validator: Self::ValidatorId) {
+    log::error!(
+      "validator {} was slashed on tributary {}",
+      hex::encode(validator),
+      hex::encode(self.genesis)
+    );
+  }
+
+  async fn validate(&mut self, block: &Self::Block) -> Result<(), TendermintBlockError> {
+    let block =
+      Block::read::<&[u8]>(&mut block.0.as_ref()).map_err(|_| TendermintBlockError::Fatal)?;
+    self.blockchain.verify_block(&block).map_err(|e| match e {
+      BlockError::TransactionError(TransactionError::MissingProvided(_)) => {
+        TendermintBlockError::Temporal
+      }
+      _ => TendermintBlockError::Fatal,
+    })
+  }
+
+  async fn add_block(
+    &mut self,
+    block: Self::Block,
+    _commit: Commit<Self::SignatureScheme>,
+  ) -> Option<Self::Block> {
+    let invalid_block = || {
+      // There's a fatal flaw in the code, it's behind a hard fork, or the validators turned
+      // malicious
+      // All justify a halt to then achieve social consensus from
+      // TODO: Under multiple validator sets, a small validator set turning malicious knocks
+      // off the entire network. That's an unacceptable DoS.
+      panic!("validators added invalid block to tributary {}", hex::encode(self.genesis));
+    };
+
+    let Ok(block) = Block::read::<&[u8]>(&mut block.0.as_ref()) else {
+      return invalid_block();
+    };
+
+    loop {
+      match self.blockchain.add_block(&block) {
+        Ok(()) => break,
+        Err(BlockError::TransactionError(TransactionError::MissingProvided(hash))) => {
+          log::error!(
+            "missing provided transaction {} which other validators on tributary {} had",
+            hex::encode(hash),
+            hex::encode(self.genesis)
+          );
+          sleep(Duration::from_secs(30)).await;
+        }
+        _ => return invalid_block(),
+      }
+    }
+
+    // TODO: Handle the commit and return the next proposal
+    todo!()
+  }
+}

coordinator/tributary/src/tests/blockchain.rs

@@ -35,7 +35,7 @@ fn block_addition() {
   assert_eq!(block.header.parent, genesis);
   assert_eq!(block.header.transactions, [0; 32]);
   blockchain.verify_block(&block).unwrap();
-  assert!(blockchain.add_block(&block));
+  assert!(blockchain.add_block(&block).is_ok());
   assert_eq!(blockchain.tip(), block.hash());
 }
 
@@ -155,7 +155,7 @@ fn signed_transaction() {
 
     // Verify and add the block
     blockchain.verify_block(&block).unwrap();
-    assert!(blockchain.add_block(&block));
+    assert!(blockchain.add_block(&block).is_ok());
     assert_eq!(blockchain.tip(), block.hash());
   };
 
@@ -194,11 +194,11 @@ fn provided_transaction() {
   blockchain.verify_block(&block).unwrap();
 
   // add_block should work for verified blocks
-  assert!(blockchain.add_block(&block));
+  assert!(blockchain.add_block(&block).is_ok());
 
   let block = Block::new(blockchain.tip(), &txs, HashMap::new());
   // The provided transaction should no longer considered provided, causing this error
   assert!(blockchain.verify_block(&block).is_err());
   // add_block should fail for unverified provided transactions if told to add them
-  assert!(!blockchain.add_block(&block));
+  assert!(blockchain.add_block(&block).is_err());
 }

coordinator/tributary/src/transaction.rs

@@ -15,12 +15,18 @@ use crate::ReadWrite;
 
 #[derive(Clone, PartialEq, Eq, Debug, Error)]
 pub enum TransactionError {
-  /// This transaction was perceived as invalid against the current state.
-  #[error("transaction temporally invalid")]
-  Temporal,
-  /// This transaction is definitively invalid.
-  #[error("transaction definitively invalid")]
-  Fatal,
+  /// A provided transaction wasn't locally provided.
+  #[error("provided transaction wasn't locally provided")]
+  MissingProvided([u8; 32]),
+  /// This transaction's signer isn't a participant.
+  #[error("invalid signer")]
+  InvalidSigner,
+  /// This transaction's nonce isn't the prior nonce plus one.
+  #[error("invalid nonce")]
+  InvalidNonce,
+  /// This transaction's signature is invalid.
+  #[error("invalid signature")]
+  InvalidSignature,
 }
 
 /// Data for a signed transaction.
@@ -100,24 +106,25 @@ pub(crate) fn verify_transaction<T: Transaction>(
 
   match tx.kind() {
     TransactionKind::Provided => {
-      if !locally_provided.remove(&tx.hash()) {
-        Err(TransactionError::Temporal)?;
+      let hash = tx.hash();
+      if !locally_provided.remove(&hash) {
+        Err(TransactionError::MissingProvided(hash))?;
       }
     }
     TransactionKind::Unsigned => {}
     TransactionKind::Signed(Signed { signer, nonce, signature }) => {
       if let Some(next_nonce) = next_nonces.get(signer) {
         if nonce != next_nonce {
-          Err(TransactionError::Temporal)?;
+          Err(TransactionError::InvalidNonce)?;
         }
       } else {
         // Not a participant
-        Err(TransactionError::Fatal)?;
+        Err(TransactionError::InvalidSigner)?;
       }
 
       // TODO: Use Schnorr half-aggregation and a batch verification here
       if !signature.verify(*signer, tx.sig_hash(genesis)) {
-        Err(TransactionError::Fatal)?;
+        Err(TransactionError::InvalidSignature)?;
       }
 
       next_nonces.insert(*signer, nonce + 1);

coordinator/tributary/tendermint/src/ext.rs

@@ -241,23 +241,30 @@ pub trait Network: Send + Sync {
     commit.validators.iter().map(|v| weights.weight(*v)).sum::<u64>() >= weights.threshold()
   }
 
-  /// Broadcast a message to the other validators. If authenticated channels have already been
-  /// established, this will double-authenticate. Switching to unauthenticated channels in a system
-  /// already providing authenticated channels is not recommended as this is a minor, temporal
-  /// inefficiency while downgrading channels may have wider implications.
+  /// Broadcast a message to the other validators.
+  ///
+  /// If authenticated channels have already been established, this will double-authenticate.
+  /// Switching to unauthenticated channels in a system already providing authenticated channels is
+  /// not recommended as this is a minor, temporal inefficiency, while downgrading channels may
+  /// have wider implications.
   async fn broadcast(&mut self, msg: SignedMessageFor<Self>);
 
   /// Trigger a slash for the validator in question who was definitively malicious.
+  ///
   /// The exact process of triggering a slash is undefined and left to the network as a whole.
   async fn slash(&mut self, validator: Self::ValidatorId);
 
   /// Validate a block.
   async fn validate(&mut self, block: &Self::Block) -> Result<(), BlockError>;
-  /// Add a block, returning the proposal for the next one. It's possible a block, which was never
-  /// validated or even failed validation, may be passed here if a supermajority of validators did
-  /// consider it valid and created a commit for it. This deviates from the paper which will have a
-  /// local node refuse to decide on a block it considers invalid. This library acknowledges the
-  /// network did decide on it, leaving handling of it to the network, and outside of this scope.
+
+  /// Add a block, returning the proposal for the next one.
+  ///
+  /// It's possible a block, which was never validated or even failed validation, may be passed
+  /// here if a supermajority of validators did consider it valid and created a commit for it.
+  ///
+  /// This deviates from the paper which will have a local node refuse to decide on a block it
+  /// considers invalid. This library acknowledges the network did decide on it, leaving handling
+  /// of it to the network, and outside of this scope.
   async fn add_block(
     &mut self,
     block: Self::Block,