Add basic transaction/block code to Tributary

coordinator/tributary/src/block.rs

@@ -0,0 +1,116 @@
+use std::{
+  io,
+  collections::{HashSet, HashMap},
+};
+
+use thiserror::Error;
+
+use blake2::{Digest, Blake2s256};
+
+use ciphersuite::{Ciphersuite, Ristretto};
+
+#[derive(Clone, PartialEq, Eq, Debug, Error)]
+pub enum BlockError {
+  /// Header specified a parent which wasn't the chain tip.
+  #[error("header doesn't build off the chain tip")]
+  InvalidParent,
+  /// Header specified an invalid transactions merkle tree hash.
+  #[error("header transactions hash is incorrect")]
+  InvalidTransactions,
+  /// An included transaction was invalid.
+  #[error("included transaction had an error")]
+  TransactionError(TransactionError),
+}
+
+use crate::{ReadWrite, TransactionError, Transaction, merkle, verify_transaction};
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct BlockHeader {
+  parent: [u8; 32],
+  transactions: [u8; 32],
+}
+
+impl ReadWrite for BlockHeader {
+  fn read<R: io::Read>(reader: &mut R) -> io::Result<Self> {
+    let mut header = BlockHeader { parent: [0; 32], transactions: [0; 32] };
+    reader.read_exact(&mut header.parent)?;
+    reader.read_exact(&mut header.transactions)?;
+    Ok(header)
+  }
+
+  fn write<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
+    writer.write_all(&self.parent)?;
+    writer.write_all(&self.transactions)
+  }
+}
+
+impl BlockHeader {
+  fn hash(&self) -> [u8; 32] {
+    Blake2s256::digest([b"tributary_block".as_ref(), &self.serialize()].concat()).into()
+  }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Block<T: Transaction> {
+  header: BlockHeader,
+  transactions: Vec<T>,
+}
+
+impl<T: Transaction> ReadWrite for Block<T> {
+  fn read<R: io::Read>(reader: &mut R) -> io::Result<Self> {
+    let header = BlockHeader::read(reader)?;
+
+    let mut txs = [0; 4];
+    reader.read_exact(&mut txs)?;
+    let txs = u32::from_le_bytes(txs);
+
+    let mut transactions = Vec::with_capacity(usize::try_from(txs).unwrap());
+    for _ in 0 .. txs {
+      transactions.push(T::read(reader)?);
+    }
+
+    Ok(Block { header, transactions })
+  }
+
+  fn write<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
+    self.header.write(writer)?;
+    writer.write_all(&u32::try_from(self.transactions.len()).unwrap().to_le_bytes())?;
+    for tx in &self.transactions {
+      tx.write(writer)?;
+    }
+    Ok(())
+  }
+}
+
+impl<T: Transaction> Block<T> {
+  pub fn hash(&self) -> [u8; 32] {
+    self.header.hash()
+  }
+
+  pub fn verify(
+    &self,
+    last_block: [u8; 32],
+    locally_provided: &mut HashSet<[u8; 32]>,
+    next_nonces: &mut HashMap<<Ristretto as Ciphersuite>::G, u32>,
+  ) -> Result<(), BlockError> {
+    if self.header.parent != last_block {
+      Err(BlockError::InvalidParent)?;
+    }
+
+    let mut txs = Vec::with_capacity(self.transactions.len());
+    for tx in &self.transactions {
+      match verify_transaction(tx, locally_provided, next_nonces) {
+        Ok(()) => {}
+        Err(e) => Err(BlockError::TransactionError(e))?,
+      }
+
+      txs.push(tx.hash());
+    }
+
+    if merkle(&txs) != self.header.transactions {
+      Err(BlockError::InvalidTransactions)?;
+    }
+
+    Ok(())
+  }
+}