feat: tx forwarder

eth_sendRawTransaction will forward transactions into --upstream-rpc-url, if specified in cli args.

src/tx_forwarder.rs

@@ -0,0 +1,44 @@
+use alloy_primitives::{Bytes, B256};
+use jsonrpsee::{
+    http_client::{HttpClient, HttpClientBuilder},
+    proc_macros::rpc,
+    types::{error::INTERNAL_ERROR_CODE, ErrorObject},
+};
+use jsonrpsee_core::{async_trait, client::ClientT, ClientError, RpcResult};
+
+#[rpc(server, namespace = "eth")]
+pub trait EthForwarderApi {
+    #[method(name = "sendRawTransaction")]
+    async fn send_raw_transaction(&self, tx: Bytes) -> RpcResult<B256>;
+}
+
+pub struct EthForwarderExt {
+    client: HttpClient,
+}
+
+impl EthForwarderExt {
+    pub fn new(upstream_rpc_url: String) -> Self {
+        let client =
+            HttpClientBuilder::default().build(upstream_rpc_url).expect("Failed to build client");
+
+        Self { client }
+    }
+}
+
+#[async_trait]
+impl EthForwarderApiServer for EthForwarderExt {
+    async fn send_raw_transaction(&self, tx: Bytes) -> RpcResult<B256> {
+        let txhash =
+            self.client.clone().request("eth_sendRawTransaction", vec![tx]).await.map_err(|e| {
+                match e {
+                    ClientError::Call(e) => e,
+                    _ => ErrorObject::owned(
+                        INTERNAL_ERROR_CODE,
+                        format!("Failed to send transaction: {e:?}"),
+                        Some(()),
+                    ),
+                }
+            })?;
+        Ok(txhash)
+    }
+}