Merge #1472

1472: Fix reorg risks with forced exits r=Deniallugo a=StanislavBreadless

We do accept transactions after small amount of confirmations, but in order to protect against the reorgs we check also past blocks multiple times.

Co-authored-by: Stanislav Bezkorovainyi <[email protected]>

core/bin/zksync_forced_exit_requests/src/eth_watch.rs

@@ -307,9 +307,13 @@ where
             return;
         };
 
+        let block_to_watch_from = self
+            .last_viewed_block
+            .saturating_sub(self.config.forced_exit_requests.blocks_check_amount);
+
         let events = self
             .eth_client
-            .get_funds_received_events(self.last_viewed_block + 1, last_confirmed_block)
+            .get_funds_received_events(block_to_watch_from, last_confirmed_block)
             .await;
 
         let events = match events {

core/lib/config/src/configs/forced_exit_requests.rs

@@ -26,6 +26,7 @@ struct ForcedExitRequestsInternalConfig {
     pub sender_eth_private_key: H256,
     pub sender_account_address: Address,
     pub expiration_period: u64,
+    pub blocks_check_amount: u64,
     pub eth_node_poll_interval: u64,
 }
 
@@ -42,6 +43,7 @@ pub struct ForcedExitRequestsConfig {
     pub sender_eth_private_key: H256,
     pub sender_account_address: Address,
     pub expiration_period: u64,
+    pub blocks_check_amount: u64,
     pub eth_node_poll_interval: u64,
 }
 
@@ -83,6 +85,7 @@ impl ForcedExitRequestsConfig {
             sender_eth_private_key: config.sender_eth_private_key,
             sender_account_address: config.sender_account_address,
             expiration_period: config.expiration_period,
+            blocks_check_amount: config.blocks_check_amount,
             eth_node_poll_interval: config.eth_node_poll_interval,
         }
     }

etc/env/base/forced_exit_requests.toml

@@ -37,5 +37,12 @@ withdrawal_threshold=1000000000000000000
 # to set the same account as the one that sends the txs for retrieving the fees from the smart contract 
 fee_receiver="0x1963917ba0b44A879cf6248387C1d51A0F11669d"
 
+
+# The amount of blocks we look into beyound the waiting confirmations
+# Basically this ensures that we do not skip a transaction that has become too old due to a 
+# reorg
+blocks_check_amount=10
+
 # How often we want to poll the Ethereum node (in milliseconds).
 eth_node_poll_interval=300
+