Add consensus coinbase checks (#593)

* add coinbase check and test case

Co-authored-by: Jane Lusby <jane@zfnd.org>

zebra-chain/src/test/generate.rs

@@ -3,10 +3,7 @@ use chrono::{DateTime, NaiveDateTime, Utc};
 use std::sync::Arc;
 
 use crate::{
-    block::{Block, BlockHeader, BlockHeaderHash, MAX_BLOCK_BYTES},
+    block::{Block, BlockHeader, MAX_BLOCK_BYTES},
-    equihash_solution::EquihashSolution,
-    merkle_tree::MerkleTreeRootHash,
-    note_commitment_tree::SaplingNoteTreeRootHash,
     serialization::{ZcashDeserialize, ZcashSerialize},
     transaction::{Transaction, TransparentInput, TransparentOutput},
     types::LockTime,
@@ -14,17 +11,7 @@ use crate::{
 
 /// Generate a block header
 pub fn block_header() -> BlockHeader {
-    let some_bytes = [0; 32];
+    BlockHeader::zcash_deserialize(&zebra_test::vectors::DUMMY_HEADER[..]).unwrap()
-    BlockHeader {
-        version: 4,
-        previous_block_hash: BlockHeaderHash(some_bytes),
-        merkle_root_hash: MerkleTreeRootHash(some_bytes),
-        final_sapling_root_hash: SaplingNoteTreeRootHash(some_bytes),
-        time: DateTime::<Utc>::from_utc(NaiveDateTime::from_timestamp(61, 0), Utc),
-        bits: 0,
-        nonce: some_bytes,
-        solution: EquihashSolution([0; 1344]),
-    }
 }
 
 /// Generate a block with multiple transactions just below limit

zebra-chain/src/transaction.rs

@@ -130,4 +130,12 @@ impl Transaction {
             Transaction::V4 { expiry_height, .. } => Some(*expiry_height),
         }
     }
+
+    /// Returns `true` if transaction contains any coinbase inputs.
+    pub fn contains_coinbase_input(&self) -> bool {
+        self.inputs().any(|input| match input {
+            TransparentInput::Coinbase { .. } => true,
+            _ => false,
+        })
+    }
 }

zebra-consensus/src/verify/block.rs

@@ -50,6 +50,24 @@ pub(crate) fn node_time_check(
     }
 }
 
+/// [3.10]: https://zips.z.cash/protocol/protocol.pdf#coinbasetransactions
+pub(crate) fn coinbase_check(block: &Block) -> Result<(), Error> {
+    if block.coinbase_height().is_some() {
+        // No coinbase inputs in additional transactions allowed
+        if block
+            .transactions
+            .iter()
+            .skip(1)
+            .any(|tx| tx.contains_coinbase_input())
+        {
+            Err("coinbase input found in additional transaction")?
+        }
+        Ok(())
+    } else {
+        Err("no coinbase transaction in block")?
+    }
+}
+
 struct BlockVerifier<S> {
     /// The underlying `ZebraState`, possibly wrapped in other services.
     state_service: S,
@@ -95,6 +113,7 @@ where
             let now = Utc::now();
             node_time_check(block.header.time, now)?;
             block.header.is_equihash_solution_valid()?;
+            coinbase_check(block.as_ref())?;
 
             // `Tower::Buffer` requires a 1:1 relationship between `poll()`s
             // and `call()`s, because it reserves a buffer slot in each
@@ -158,7 +177,9 @@ mod tests {
     use tower::{util::ServiceExt, Service};
 
     use zebra_chain::block::Block;
+    use zebra_chain::block::BlockHeader;
     use zebra_chain::serialization::ZcashDeserialize;
+    use zebra_chain::transaction::Transaction;
 
     #[test]
     fn time_check_past_block() {
@@ -499,7 +520,8 @@ mod tests {
 
         // Service variables
         let state_service = Box::new(zebra_state::in_memory::init());
-        let mut block_verifier = super::init(state_service);
+        let mut block_verifier = super::init(state_service.clone());
+
         let ready_verifier_service = block_verifier.ready_and().await.map_err(|e| eyre!(e))?;
 
         // Get a valid block
@@ -516,6 +538,8 @@ mod tests {
         // Change nonce to something invalid
         block.header.nonce = [0; 32];
 
+        let ready_verifier_service = block_verifier.ready_and().await.map_err(|e| eyre!(e))?;
+
         // Error: invalid equihash solution for BlockHeader
         ready_verifier_service
             .call(Arc::new(block.clone()))
@@ -524,4 +548,71 @@ mod tests {
 
         Ok(())
     }
+
+    #[tokio::test]
+    #[spandoc::spandoc]
+    async fn coinbase() -> Result<(), Report> {
+        zebra_test::init();
+
+        // Service variables
+        let state_service = Box::new(zebra_state::in_memory::init());
+        let mut block_verifier = super::init(state_service.clone());
+
+        // Get a header of a block
+        let header =
+            BlockHeader::zcash_deserialize(&zebra_test::vectors::DUMMY_HEADER[..]).unwrap();
+
+        let ready_verifier_service = block_verifier.ready_and().await.map_err(|e| eyre!(e))?;
+
+        // Test 1: Empty transaction
+        let block = Block {
+            header,
+            transactions: Vec::new(),
+        };
+
+        // Error: no coinbase transaction in block
+        ready_verifier_service
+            .call(Arc::new(block.clone()))
+            .await
+            .expect_err("fail with no coinbase transaction in block");
+
+        let ready_verifier_service = block_verifier.ready_and().await.map_err(|e| eyre!(e))?;
+
+        // Test 2: Transaction at first position is not coinbase
+        let mut transactions = Vec::new();
+        let tx = Transaction::zcash_deserialize(&zebra_test::vectors::DUMMY_TX1[..]).unwrap();
+        transactions.push(Arc::new(tx));
+        let block = Block {
+            header,
+            transactions,
+        };
+
+        // Error: no coinbase transaction in block
+        ready_verifier_service
+            .call(Arc::new(block))
+            .await
+            .expect_err("fail with no coinbase transaction in block");
+
+        let ready_verifier_service = block_verifier.ready_and().await.map_err(|e| eyre!(e))?;
+
+        // Test 3: Invalid coinbase position
+        let mut block =
+            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..])?;
+        assert_eq!(block.transactions.len(), 1);
+
+        // Extract the coinbase transaction from the block
+        let coinbase_transaction = block.transactions.get(0).unwrap().clone();
+
+        // Add another coinbase transaction to block
+        block.transactions.push(coinbase_transaction);
+        assert_eq!(block.transactions.len(), 2);
+
+        // Error: coinbase input found in additional transaction
+        ready_verifier_service
+            .call(Arc::new(block))
+            .await
+            .expect_err("fail with coinbase input found in additional transaction");
+
+        Ok(())
+    }
 }