feat: add HistoricalRpcClient for forwarding legacy RPC requests

crates/optimism/rpc/src/historical.rs

@@ -0,0 +1,68 @@
+//! Client support for optimism historical RPC requests.
+
+use crate::sequencer::Error;
+use alloy_json_rpc::{RpcRecv, RpcSend};
+use alloy_rpc_client::RpcClient;
+use std::sync::Arc;
+use tracing::warn;
+
+/// A client that can be used to forward RPC requests for historical data to an endpoint.
+///
+/// This is intended to be used for OP-Mainnet pre-bedrock data, allowing users to query historical
+/// state.
+#[derive(Debug, Clone)]
+pub struct HistoricalRpcClient {
+    inner: Arc<HistoricalRpcClientInner>,
+}
+
+impl HistoricalRpcClient {
+    /// Constructs a new historical RPC client with the given endpoint URL.
+    pub async fn new(endpoint: &str) -> Result<Self, Error> {
+        let client = RpcClient::new_http(
+            endpoint.parse::<reqwest::Url>().map_err(|err| Error::InvalidUrl(err.to_string()))?,
+        );
+
+        Ok(Self {
+            inner: Arc::new(HistoricalRpcClientInner {
+                historical_endpoint: endpoint.to_string(),
+                client,
+            }),
+        })
+    }
+
+    /// Returns a reference to the underlying RPC client
+    fn client(&self) -> &RpcClient {
+        &self.inner.client
+    }
+
+    /// Forwards a JSON-RPC request to the historical endpoint
+    pub async fn request<Params: RpcSend, Resp: RpcRecv>(
+        &self,
+        method: &str,
+        params: Params,
+    ) -> Result<Resp, Error> {
+        let resp =
+            self.client().request::<Params, Resp>(method.to_string(), params).await.inspect_err(
+                |err| {
+                    warn!(
+                        target: "rpc::historical",
+                        %err,
+                        "HTTP request to historical endpoint failed"
+                    );
+                },
+            )?;
+
+        Ok(resp)
+    }
+
+    /// Returns the configured historical endpoint URL
+    pub fn endpoint(&self) -> &str {
+        &self.inner.historical_endpoint
+    }
+}
+
+#[derive(Debug)]
+struct HistoricalRpcClientInner {
+    historical_endpoint: String,
+    client: RpcClient,
+}

crates/optimism/rpc/src/lib.rs

@@ -11,6 +11,7 @@
 pub mod engine;
 pub mod error;
 pub mod eth;
+pub mod historical;
 pub mod miner;
 pub mod sequencer;
 pub mod witness;