Use gRPC query ConnectionParams instead of /genesis to verify max_block_time

.changelog/unreleased/improvements/ibc-relayer/4143-use-connection-params-in-validate-params.md

@@ -0,0 +1,4 @@
+- Use the `ibc.core.connection.v1.ConnectionParams` gRPC query to retrieve  `maxExpectedTimePerBlock` 
+  and check it against the configured `max_block_time` instead of using the `/genesis` endpoint. 
+  This improves both startup times and reliability for most chains.
+  ([\#4143](https://github.com/informalsystems/hermes/issues/4143))

crates/relayer/src/chain/cosmos.rs

@@ -1,5 +1,6 @@
 use alloc::sync::Arc;
 use core::{future::Future, str::FromStr, time::Duration};
+use query::connection::query_connection_params;
 use std::{cmp::Ordering, thread};
 
 use bytes::{Buf, Bytes};
@@ -8,7 +9,7 @@ use num_bigint::BigInt;
 use tokio::runtime::Runtime as TokioRuntime;
 use tonic::codegen::http::Uri;
 use tonic::metadata::AsciiMetadataValue;
-use tracing::{debug, error, info, instrument, trace, warn};
+use tracing::{debug, error, instrument, trace, warn};
 
 use ibc_proto::cosmos::base::node::v1beta1::ConfigResponse;
 use ibc_proto::cosmos::base::tendermint::v1beta1::service_client::ServiceClient;
@@ -113,7 +114,6 @@ use crate::util::pretty::{
 use crate::HERMES_VERSION;
 
 use self::gas::dynamic_gas_price;
-use self::types::app_state::GenesisAppState;
 use self::types::gas::GasConfig;
 use self::version::Specs;
 
@@ -296,27 +296,30 @@ impl CosmosSdkChain {
             ));
         }
 
-        // Query /genesis RPC endpoint to retrieve the `max_expected_time_per_block` value to use as `max_block_time`.
-        // If it is not found, keep the configured `max_block_time`.
-        match self.block_on(self.rpc_client.genesis::<GenesisAppState>()) {
-            Ok(genesis_reponse) => {
-                let old_max_block_time = self.config.max_block_time;
-                let new_max_block_time =
-                    Duration::from_nanos(genesis_reponse.app_state.max_expected_time_per_block());
-
-                if old_max_block_time.as_secs() != new_max_block_time.as_secs() {
-                    self.config.max_block_time = new_max_block_time;
-
-                    info!(
-                        "Updated `max_block_time` using /genesis endpoint. Old value: `{}s`, new value: `{}s`",
-                        old_max_block_time.as_secs(),
-                        self.config.max_block_time.as_secs()
+        // Query Connection Params with gRPC endpoint to retrieve the `max_expected_time_per_block` value and verify the
+        // configured `max_block_time`.
+        // If it is not found, the verification for the configured `max_block_time` is skipped.
+        match self.block_on(query_connection_params(&self.grpc_addr)) {
+            Ok(params) => {
+                debug!(
+                    "queried `max_expected_time_per_block`: `{}ns`",
+                    params.max_expected_time_per_block
+                );
+                let new_max_block_time = Duration::from_nanos(params.max_expected_time_per_block);
+
+                if new_max_block_time != self.config.max_block_time {
+                    warn!(
+                        "configured `max_block_time` value of `{}s` does not match queried value of `{}s`. \
+                        `max_block_time` will be updated with queried value",
+                        self.config.max_block_time.as_secs(),
+                        new_max_block_time.as_secs(),
                     );
+                    self.config.max_block_time = new_max_block_time;
                 }
             }
             Err(e) => {
                 warn!(
-                    "Will use fallback value for max_block_time: `{}s`. Error: {e}",
+                    "configured value for max_block_time: `{}s` could not be verified. Error: {e}",
                     self.config.max_block_time.as_secs()
                 );
             }

crates/relayer/src/chain/cosmos/query.rs

@@ -16,6 +16,7 @@ use crate::error::Error;
 
 pub mod account;
 pub mod balance;
+pub mod connection;
 pub mod consensus_state;
 pub mod custom;
 pub mod denom_trace;

crates/relayer/src/chain/cosmos/query/connection.rs

@@ -0,0 +1,30 @@
+use http::uri::Uri;
+
+use ibc_proto::ibc::core::connection::v1::query_client::QueryClient;
+use ibc_proto::ibc::core::connection::v1::Params;
+use ibc_proto::ibc::core::connection::v1::QueryConnectionParamsRequest;
+
+use crate::config::default::max_grpc_decoding_size;
+use crate::error::Error;
+
+/// Uses the GRPC client to retrieve the connection params
+pub async fn query_connection_params(grpc_address: &Uri) -> Result<Params, Error> {
+    let mut client = QueryClient::connect(grpc_address.clone())
+        .await
+        .map_err(Error::grpc_transport)?;
+
+    client = client.max_decoding_message_size(max_grpc_decoding_size().get_bytes() as usize);
+
+    let request = tonic::Request::new(QueryConnectionParamsRequest {});
+
+    let response = client
+        .connection_params(request)
+        .await
+        .map(|r| r.into_inner())
+        .map_err(|e| Error::grpc_status(e, "query_connection_params".to_owned()))?;
+
+    // Querying connection params might not be found
+    let params = response.params.ok_or_else(Error::empty_connection_params)?;
+
+    Ok(params)
+}

crates/relayer/src/chain/cosmos/types/mod.rs

@@ -1,5 +1,4 @@
 pub mod account;
-pub mod app_state;
 pub mod config;
 pub mod events;
 pub mod gas;

crates/relayer/src/error.rs

@@ -143,6 +143,9 @@ define_error! {
         EmptyUpgradedClientState
             |_| { "found no upgraded client state" },
 
+        EmptyConnectionParams
+            |_| { "connection params not found" },
+
         ConsensusStateTypeMismatch
             {
                 expected: ClientType,