blockchain/contract_store: added missing functions so transaction verification now operates purelly over an overlay

src/blockchain/contract_store.rs

@@ -71,6 +71,18 @@ impl WasmStoreOverlay {
         Ok(Self(overlay))
     }
 
+    /// Fetches the bincode for a given ContractId
+    /// Returns an error if the bincode is not found.
+    pub fn get(&self, contract_id: ContractId) -> Result<Vec<u8>> {
+        if let Some(bincode) =
+            self.0.lock().unwrap().get(SLED_BINCODE_TREE, &serialize(&contract_id))?
+        {
+            return Ok(bincode.to_vec())
+        }
+
+        Err(Error::WasmBincodeNotFound)
+    }
+
     /// Inserts or replaces the bincode for a given ContractId
     pub fn insert(&self, contract_id: ContractId, bincode: &[u8]) -> Result<()> {
         if let Err(e) =
@@ -284,4 +296,33 @@ impl ContractStateStoreOverlay {
         lock.open_tree(&ptr)?;
         Ok(ptr)
     }
+
+    /// Abstraction function for fetching a `ZkBinary` and its respective `VerifyingKey`
+    /// from a contract's zkas sled tree.
+    pub fn get_zkas(
+        &self,
+        contract_id: &ContractId,
+        zkas_ns: &str,
+    ) -> Result<(ZkBinary, VerifyingKey)> {
+        debug!(target: "blockchain::contractstore", "Looking up \"{}:{}\" zkas circuit & vk", contract_id, zkas_ns);
+
+        let zkas_tree = self.lookup(contract_id, SMART_CONTRACT_ZKAS_DB_NAME)?;
+
+        let Some(zkas_bytes) = self.0.lock().unwrap().get(&zkas_tree, &serialize(&zkas_ns))? else {
+            return Err(Error::ZkasBincodeNotFound)
+        };
+
+        // If anything in this function panics, that means corrupted data managed
+        // to get into this sled tree. This should not be possible.
+        let (zkbin, vkbin): (Vec<u8>, Vec<u8>) = deserialize(&zkas_bytes).unwrap();
+
+        // The first vec is the compiled zkas binary
+        let zkbin = ZkBinary::decode(&zkbin).unwrap();
+
+        // The second one is the serialized VerifyingKey for it
+        let mut vk_buf = Cursor::new(vkbin);
+        let vk = VerifyingKey::read::<Cursor<Vec<u8>>, ZkCircuit>(&mut vk_buf).unwrap();
+
+        Ok((zkbin, vk))
+    }
 }

src/validator/mod.rs

@@ -199,7 +199,7 @@ impl Validator {
             tx.calls.encode(&mut payload)?; // Actual call data
 
             debug!(target: "validator", "Instantiating WASM runtime");
-            let wasm = self.blockchain.wasm_bincode.get(call.contract_id)?;
+            let wasm = blockchain_overlay.lock().unwrap().wasm_bincode.get(call.contract_id)?;
 
             let mut runtime = Runtime::new(
                 &wasm,
@@ -232,11 +232,11 @@ impl Validator {
                     continue
                 }
 
-                let (_, vk) = self.blockchain.contracts.get_zkas(
-                    &self.blockchain.sled_db,
-                    &call.contract_id,
-                    zkas_ns,
-                )?;
+                let (_, vk) = blockchain_overlay
+                    .lock()
+                    .unwrap()
+                    .contracts
+                    .get_zkas(&call.contract_id, zkas_ns)?;
 
                 inner_vk_map.insert(zkas_ns.to_string(), vk);
             }