Bump sync-tolerance-epoch and make it a cli param

beacon_node/beacon_chain/src/chain_config.rs

@@ -95,6 +95,7 @@ pub struct ChainConfig {
     /// This doesn't apply if the node is the block proposer.
     pub blob_publication_batch_interval: Duration,
     pub disable_attesting: bool,
+    pub sync_tolerance_epochs: u64,
 }
 
 impl Default for ChainConfig {
@@ -131,6 +132,7 @@ impl Default for ChainConfig {
             blob_publication_batches: 4,
             blob_publication_batch_interval: Duration::from_millis(300),
             disable_attesting: false,
+            sync_tolerance_epochs: 16,
         }
     }
 }

beacon_node/http_api/src/lib.rs

@@ -107,13 +107,6 @@ use warp_utils::{query::multi_key_query, reject::convert_rejection, uor::Unifyin
 
 const API_PREFIX: &str = "eth";
 
-/// If the node is within this many epochs from the head, we declare it to be synced regardless of
-/// the network sync state.
-///
-/// This helps prevent attacks where nodes can convince us that we're syncing some non-existent
-/// finalized head.
-const SYNC_TOLERANCE_EPOCHS: u64 = 8;
-
 /// A custom type which allows for both unsecured and TLS-enabled HTTP servers.
 type HttpServer = (SocketAddr, Pin<Box<dyn Future<Output = ()> + Send>>);
 
@@ -157,6 +150,7 @@ pub struct Config {
     pub duplicate_block_status_code: StatusCode,
     pub enable_light_client_server: bool,
     pub target_peers: usize,
+    pub sync_tolerance_epochs: usize,
 }
 
 impl Default for Config {
@@ -173,6 +167,7 @@ impl Default for Config {
             duplicate_block_status_code: StatusCode::ACCEPTED,
             enable_light_client_server: true,
             target_peers: 100,
+            sync_tolerance_epochs: 16,
         }
     }
 }
@@ -473,7 +468,8 @@ pub fn serve<T: BeaconChainTypes>(
                                     )
                                 })?;
 
-                            let tolerance = SYNC_TOLERANCE_EPOCHS * T::EthSpec::slots_per_epoch();
+                            let tolerance =
+                                chain.config.sync_tolerance_epochs * T::EthSpec::slots_per_epoch();
 
                             if head_slot + tolerance >= current_slot {
                                 Ok(())

beacon_node/src/cli.rs

@@ -561,6 +561,14 @@ pub fn cli_app() -> Command {
                 .action(ArgAction::SetTrue)
                 .display_order(0)
         )
+        .arg(
+            Arg::new("sync-tolerance-epochs")
+            .long("sync-tolerance-epochs")
+            .help("If the beacon node is within this many epochs from the head, we declare it to \
+                   be synced regardless of the network sync state")
+            .action(ArgAction::Set)
+            .display_order(0)
+        )
         .arg(
             Arg::new("http-sse-capacity-multiplier")
                 .long("http-sse-capacity-multiplier")