Panic when state blocks are inserted out of order

This panic ensures our state is not corrupted. Corrupt states can lead
to future panics when querying the chain.

zebra-consensus/src/checkpoint/tests.rs

@@ -268,7 +268,7 @@ async fn continuous_blockchain(restart_height: Option<block::Height>) -> Result<
             .cloned();
         let state_service = zebra_state::init(zebra_state::Config::ephemeral(), Mainnet);
         let mut checkpoint_verifier =
-            CheckpointVerifier::from_list(checkpoint_list, initial_tip, state_service)
+            CheckpointVerifier::from_list(checkpoint_list, initial_tip, state_service.clone())
                 .map_err(|e| eyre!(e))?;
 
         // Setup checks
@@ -305,7 +305,18 @@ async fn continuous_blockchain(restart_height: Option<block::Height>) -> Result<
         for (block, height, _hash) in blockchain {
             if let Some(restart_height) = restart_height {
                 if height <= restart_height {
-                    continue;
+                    let mut state_service = state_service.clone();
+                    /// SPANDOC: Make sure the state service is ready for block {?height}
+                    let ready_state_service =
+                        state_service.ready_and().map_err(|e| eyre!(e)).await?;
+
+                    /// SPANDOC: Add block to the state {?height}
+                    ready_state_service
+                        .call(zebra_state::Request::AddBlock {
+                            block: block.clone(),
+                        })
+                        .await
+                        .map_err(|e| eyre!(e))?;
                 }
             }
             if height > checkpoint_verifier.checkpoint_list.max_height() {

zebra-state/src/on_disk.rs

@@ -44,7 +44,42 @@ impl SledState {
 
         let block = block.into();
         let hash = block.hash();
-        let height = block.coinbase_height().unwrap();
+        let height = block
+            .coinbase_height()
+            .expect("missing height: valid blocks must have a height");
+
+        // Make sure blocks are inserted in order, as a defence in depth.
+        // See the state design RFC #0005 for details.
+        //
+        // TODO: handle multiple chains
+        match self.get_tip()? {
+            None => {
+                // This is a defence in depth - there is no need to check the
+                // genesis hash or previous block hash here.
+                assert_eq!(
+                    height,
+                    block::Height(0),
+                    "out of order block: the first block must be at the genesis height"
+                );
+            }
+            Some(tip_hash) => {
+                assert_eq!(
+                    block.header.previous_block_hash, tip_hash,
+                    "out of order block: the next block must be a child of the current tip"
+                );
+                let tip_block = self
+                    .get(tip_hash)?
+                    .expect("missing tip block: tip hashes must have a corresponding block");
+                let tip_height = tip_block
+                    .coinbase_height()
+                    .expect("missing height: valid blocks must have a height");
+                assert_eq!(
+                    height,
+                    block::Height(tip_height.0 + 1),
+                    "out of order block: the next height must be 1 greater than the tip height"
+                );
+            }
+        };
 
         let height_map = self.storage.open_tree(b"height_map")?;
         let by_hash = self.storage.open_tree(b"by_hash")?;

zebra-state/tests/basic.rs

@@ -10,7 +10,7 @@ use zebra_state::*;
 static ADD_BLOCK_TRANSCRIPT_MAINNET: Lazy<Vec<(Request, Result<Response, TransError>)>> =
     Lazy::new(|| {
         let block: Arc<_> =
-            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_415000_BYTES[..])
+            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_MAINNET_GENESIS_BYTES[..])
                 .unwrap()
                 .into();
         let hash = block.as_ref().into();
@@ -28,7 +28,7 @@ static ADD_BLOCK_TRANSCRIPT_MAINNET: Lazy<Vec<(Request, Result<Response, TransEr
 static ADD_BLOCK_TRANSCRIPT_TESTNET: Lazy<Vec<(Request, Result<Response, TransError>)>> =
     Lazy::new(|| {
         let block: Arc<_> =
-            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_TESTNET_10_BYTES[..])
+            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_TESTNET_GENESIS_BYTES[..])
                 .unwrap()
                 .into();
         let hash = block.as_ref().into();
@@ -76,7 +76,7 @@ static GET_TIP_TRANSCRIPT_TESTNET: Lazy<Vec<(Request, Result<Response, TransErro
                 .unwrap()
                 .into();
         let block1: Arc<_> =
-            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_TESTNET_10_BYTES[..])
+            Block::zcash_deserialize(&zebra_test::vectors::BLOCK_TESTNET_1_BYTES[..])
                 .unwrap()
                 .into();
         let hash0 = block0.as_ref().into();