initial commit

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "eth-proxy"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+argh = "0.1"
+anyhow = "1.0"
+futures = { version = "0.3.0", features = ["thread-pool"]}
+tokio = { version = "1", features = ["full"] }
+reqwest = { version = "0.11", features = ["json"] }
+serde_json = { version = "1.0", default-features = false, features = ["alloc"] }
+warp = "0.3"

src/main.rs

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+use std::sync::Arc;
+use warp::Filter;
+
+#[derive(argh::FromArgs)]
+/// Proxy Web3 Requests
+struct Web3ProxyConfig {
+    /// the primary Ethereum RPC server
+    #[argh(option)]
+    eth_primary_rpc: String,
+
+    /// the private Ethereum RPC server
+    #[argh(option)]
+    eth_private_rpc: String,
+
+    /// the private Ethereum RPC
+    #[argh(option, default = "8845")]
+    listen_port: u16,
+}
+
+#[tokio::main]
+async fn main() {
+    let config: Web3ProxyConfig = argh::from_env();
+
+    let config = Arc::new(config);
+
+    let listen_port = config.listen_port;
+
+    let hello = warp::path::end().map(|| format!("Hello, world!"));
+
+    let proxy_eth_filter = warp::path!("eth")
+        .and(warp::post())
+        .and(warp::body::json())
+        .then(move |json_body| proxy_eth_rpc(config.clone(), json_body))
+        .map(handle_anyhow_errors);
+
+    // TODO: relay ftm, bsc, polygon, avax, ...
+
+    let routes = warp::any().and(hello.or(proxy_eth_filter));
+
+    warp::serve(routes).run(([127, 0, 0, 1], listen_port)).await;
+}
+
+/// send the request to the approriate Ethereum RPC
+async fn proxy_eth_rpc(
+    config: Arc<Web3ProxyConfig>,
+    json_body: serde_json::Value,
+) -> anyhow::Result<impl warp::Reply> {
+    // TODO: this should be a list of servers. query all. prefer result from first server even if it is a bit late
+    // TODO: automatically rank servers based on request latency and block height
+    let eth_send_signed_transaction =
+        serde_json::Value::String("eth_sendSignedTransaction".to_string());
+
+    let upstream_server = if json_body.get("method") == Some(&eth_send_signed_transaction) {
+        // TODO: read from args
+        &config.eth_private_rpc
+    } else {
+        // TODO: read from args
+        // TODO: if querying a block older than 256 blocks old, send to an archive node. otherwise a fast sync node is fine
+        &config.eth_primary_rpc
+    };
+
+    // TODO: reuse this Client/RequestBuilder
+    let client = reqwest::Client::new();
+    let res = client.post(upstream_server).json(&json_body).send().await?;
+
+    Ok(res.text().await?)
+}
+
+/// convert result into an http response
+pub fn handle_anyhow_errors<T: warp::Reply>(res: anyhow::Result<T>) -> Box<dyn warp::Reply> {
+    match res {
+        Ok(r) => Box::new(r.into_response()),
+        // TODO: json error?
+        Err(e) => Box::new(warp::reply::with_status(
+            format!("{}", e),
+            reqwest::StatusCode::INTERNAL_SERVER_ERROR,
+        )),
+    }
+}