Allow disabling header verification by setting trusted_node = true in the chain config

.changelog/unreleased/features/3330-disable-verify.md

@@ -0,0 +1,15 @@
+- Add a new `trusted_node` setting to the per-chain configuration to
+  specify whether or not the full node Hermes connects to is trusted.
+  If not trusted (ie. `trusted_node = false`), Hermes will verify headers
+  included in the `ClientUpdate` message using the light client.
+
+  If the full node is configured as trusted then, in addition to headers not being verified,
+  the verification traces will not be provided.
+  This may cause failure in client updates after significant change in validator sets.
+
+  > **Warning**
+  > Setting this flag to `true` may reduce latency but at the expense of
+  > potentially sending invalid client updates to the chain, only use
+  > when latency is more critical than operating costs. Use at your own risk.
+
+  ([\#3330](https://github.com/informalsystems/hermes/issues/3330))

config.toml

@@ -132,6 +132,17 @@ websocket_addr = 'ws://127.0.0.1:26657/websocket'
 # Hermes uses a large preconfigured timeout (on the order of minutes).
 rpc_timeout = '10s'
 
+# Experimental: Whether or not the full node is trusted.
+#
+# If not trusted, Hermes will verify headers included in the `ClientUpdate` message using the light client.
+#
+# Note: If the full node is configured as trusted then, in addition to headers not being verified,
+#       the verification traces will not be provided.
+#       This may cause failure in client updates after significant change in validator sets.
+#
+# Default: false
+trusted_node = false
+
 # Delay until event batch is emitted if no NewBlock events have come yet
 batch_delay = '500ms'
 
@@ -315,6 +326,7 @@ grpc_addr = 'http://127.0.0.1:9091'
 websocket_addr = 'ws://127.0.0.1:26557/websocket'
 rpc_timeout = '10s'
 batch_delay = '500ms'
+trusted_node = false
 account_prefix = 'cosmos'
 key_name = 'testkey'
 store_prefix = 'ibc'

crates/relayer-cli/Cargo.toml

@@ -18,7 +18,7 @@ default-run = "hermes"
 name = "hermes"
 
 [features]
-default     = ["telemetry", "rest-server", "std", "eyre_tracer",]
+default     = ["telemetry", "rest-server", "std", "eyre_tracer"]
 std         = ["flex-error/std"]
 eyre_tracer = ["flex-error/eyre_tracer"]
 profiling   = ["ibc-relayer/profiling"]

crates/relayer-cli/src/chain_registry.rs

@@ -122,6 +122,7 @@ where
         grpc_addr: grpc_address,
         rpc_timeout: default::rpc_timeout(),
         batch_delay: default::batch_delay(),
+        trusted_node: default::trusted_node(),
         genesis_restart: None,
         account_prefix: chain_data.bech32_prefix,
         key_name: String::new(),

crates/relayer/src/config.rs

@@ -185,6 +185,10 @@ pub mod default {
         Duration::from_secs(30)
     }
 
+    pub fn trusted_node() -> bool {
+        false
+    }
+
     pub fn connection_delay() -> Duration {
         ZERO_DURATION
     }
@@ -459,6 +463,8 @@ pub struct ChainConfig {
     pub rpc_timeout: Duration,
     #[serde(default = "default::batch_delay", with = "humantime_serde")]
     pub batch_delay: Duration,
+    #[serde(default = "default::trusted_node")]
+    pub trusted_node: bool,
     pub account_prefix: String,
     pub key_name: String,
     #[serde(default)]

crates/relayer/src/light_client/tendermint.rs

@@ -49,6 +49,7 @@ pub struct LightClient {
     chain_id: ChainId,
     peer_id: PeerId,
     io: AnyIo,
+    enable_verification: bool,
 }
 
 impl super::LightClient<CosmosSdkChain> for LightClient {
@@ -87,6 +88,15 @@ impl super::LightClient<CosmosSdkChain> for LightClient {
     ) -> Result<Verified<LightBlock>, Error> {
         trace!(%trusted_height, %target_height, "light client verification");
 
+        if !self.enable_verification {
+            let target = self.fetch(target_height)?;
+
+            return Ok(Verified {
+                target,
+                supporting: vec![],
+            });
+        }
+
         let client = self.prepare_client(client_state, now)?;
         let mut state = self.prepare_state(trusted_height)?;
 
@@ -279,10 +289,17 @@ impl LightClient {
             }
         };
 
+        // If the full node is configured as trusted then, in addition to headers not being verified,
+        // the verification traces will not be provided. This may cause failure in client
+        // updates after significant change in validator sets.
+        let enable_verification = !config.trusted_node;
+
         Ok(Self {
             chain_id: config.id.clone(),
             peer_id,
             io,
+
+            enable_verification,
         })
     }
 

tools/test-framework/src/types/single/node.rs

@@ -142,6 +142,7 @@ impl FullNode {
             grpc_addr: Url::from_str(&self.chain_driver.grpc_address())?,
             rpc_timeout: ibc_relayer::config::default::rpc_timeout(),
             batch_delay: ibc_relayer::config::default::batch_delay(),
+            trusted_node: false,
             genesis_restart: None,
             account_prefix: self.chain_driver.account_prefix.clone(),
             key_name: self.wallets.relayer.id.0.clone(),