web3-proxy/web3_proxy/src/frontend/rpc_proxy_ws.rs

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//! Take a user's WebSocket JSON-RPC requests and either respond from local data or proxy the request to a backend rpc server.
//!
//! WebSockets are the preferred method of receiving requests, but not all clients have good support.
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use super::authorization::{ip_is_authorized, key_is_authorized, Authorization, RequestMetadata};
use super::errors::{FrontendErrorResponse, FrontendResult};
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use crate::app::REQUEST_PERIOD;
use crate::app_stats::ProxyResponseStat;
use crate::{
app::Web3ProxyApp,
jsonrpc::{JsonRpcForwardedResponse, JsonRpcForwardedResponseEnum, JsonRpcRequest},
};
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use axum::headers::{Origin, Referer, UserAgent};
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use axum::{
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extract::ws::{Message, WebSocket, WebSocketUpgrade},
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extract::Path,
response::{IntoResponse, Redirect},
Extension, TypedHeader,
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};
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use axum_client_ip::ClientIp;
use axum_macros::debug_handler;
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use futures::SinkExt;
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use futures::{
future::AbortHandle,
stream::{SplitSink, SplitStream, StreamExt},
};
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use handlebars::Handlebars;
use hashbrown::HashMap;
use http::StatusCode;
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use log::{error, info, trace, warn};
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use serde_json::{json, value::RawValue};
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use std::sync::Arc;
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use std::{str::from_utf8_mut, sync::atomic::AtomicUsize};
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/// Public entrypoint for WebSocket JSON-RPC requests.
/// Defaults to rate limiting by IP address, but can also read the Authorization header for a bearer token.
#[debug_handler]
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pub async fn websocket_handler(
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Extension(app): Extension<Arc<Web3ProxyApp>>,
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ClientIp(ip): ClientIp,
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origin: Option<TypedHeader<Origin>>,
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ws_upgrade: Option<WebSocketUpgrade>,
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) -> FrontendResult {
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// TODO: i don't like logging ips. move this to trace level?
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let origin = origin.map(|x| x.0);
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let (authorization, _semaphore) = ip_is_authorized(&app, ip, origin).await?;
let authorization = Arc::new(authorization);
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match ws_upgrade {
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Some(ws) => Ok(ws
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.on_upgrade(|socket| proxy_web3_socket(app, authorization, socket))
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.into_response()),
None => {
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if let Some(redirect) = &app.config.redirect_public_url {
// this is not a websocket. redirect to a friendly page
Ok(Redirect::to(redirect).into_response())
} else {
// TODO: do not use an anyhow error. send the user a 400
Err(
anyhow::anyhow!("redirect_public_url not set. only websockets work here")
.into(),
)
}
}
}
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}
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/// Authenticated entrypoint for WebSocket JSON-RPC requests. Web3 wallets use this.
/// Rate limit and billing based on the api key in the url.
/// Can optionally authorized based on origin, referer, or user agent.
#[debug_handler]
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pub async fn websocket_handler_with_key(
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Extension(app): Extension<Arc<Web3ProxyApp>>,
ClientIp(ip): ClientIp,
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Path(rpc_key): Path<String>,
origin: Option<TypedHeader<Origin>>,
referer: Option<TypedHeader<Referer>>,
user_agent: Option<TypedHeader<UserAgent>>,
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ws_upgrade: Option<WebSocketUpgrade>,
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) -> FrontendResult {
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let rpc_key = rpc_key.parse()?;
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let (authorization, _semaphore) = key_is_authorized(
&app,
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rpc_key,
ip,
origin.map(|x| x.0),
referer.map(|x| x.0),
user_agent.map(|x| x.0),
)
.await?;
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trace!("websocket_handler_with_key {:?}", authorization);
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let authorization = Arc::new(authorization);
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match ws_upgrade {
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Some(ws_upgrade) => {
Ok(ws_upgrade.on_upgrade(move |socket| proxy_web3_socket(app, authorization, socket)))
}
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None => {
// if no websocket upgrade, this is probably a user loading the url with their browser
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// TODO: rate limit here? key_is_authorized might be enough
match (
&app.config.redirect_public_url,
&app.config.redirect_rpc_key_url,
authorization.checks.rpc_key_id,
) {
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(None, None, _) => Err(FrontendErrorResponse::StatusCode(
StatusCode::BAD_REQUEST,
"this page is for rpcs".to_string(),
None,
)),
(Some(redirect_public_url), _, None) => {
Ok(Redirect::to(redirect_public_url).into_response())
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}
(_, Some(redirect_rpc_key_url), rpc_key_id) => {
let reg = Handlebars::new();
if authorization.checks.rpc_key_id.is_none() {
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// i don't think this is possible
Err(FrontendErrorResponse::StatusCode(
StatusCode::UNAUTHORIZED,
"AUTHORIZATION header required".to_string(),
None,
))
} else {
let redirect_rpc_key_url = reg
.render_template(
redirect_rpc_key_url,
&json!({ "rpc_key_id": rpc_key_id }),
)
.expect("templating should always work");
// this is not a websocket. redirect to a page for this user
Ok(Redirect::to(&redirect_rpc_key_url).into_response())
}
}
// any other combinations get a simple error
_ => Err(FrontendErrorResponse::StatusCode(
StatusCode::BAD_REQUEST,
"this page is for rpcs".to_string(),
None,
)),
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}
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}
}
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}
async fn proxy_web3_socket(
app: Arc<Web3ProxyApp>,
authorization: Arc<Authorization>,
socket: WebSocket,
) {
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// split the websocket so we can read and write concurrently
let (ws_tx, ws_rx) = socket.split();
// create a channel for our reader and writer can communicate. todo: benchmark different channels
let (response_sender, response_receiver) = flume::unbounded::<Message>();
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tokio::spawn(write_web3_socket(response_receiver, ws_tx));
tokio::spawn(read_web3_socket(app, authorization, ws_rx, response_sender));
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}
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/// websockets support a few more methods than http clients
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async fn handle_socket_payload(
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app: Arc<Web3ProxyApp>,
authorization: &Arc<Authorization>,
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payload: &str,
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response_sender: &flume::Sender<Message>,
subscription_count: &AtomicUsize,
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subscriptions: &mut HashMap<String, AbortHandle>,
) -> Message {
// TODO: do any clients send batches over websockets?
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let (id, response) = match serde_json::from_str::<JsonRpcRequest>(payload) {
Ok(json_request) => {
// TODO: should we use this id for the subscription id? it should be unique and means we dont need an atomic
let id = json_request.id.clone();
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let response: anyhow::Result<JsonRpcForwardedResponseEnum> = match &json_request.method
[..]
{
"eth_subscribe" => {
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match app
.eth_subscribe(
authorization.clone(),
json_request,
subscription_count,
response_sender.clone(),
)
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.await
{
Ok((handle, response)) => {
// TODO: better key
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subscriptions.insert(
response
.result
.as_ref()
// TODO: what if there is an error?
.expect("response should always have a result, not an error")
.to_string(),
handle,
);
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Ok(response.into())
}
Err(err) => Err(err),
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}
}
"eth_unsubscribe" => {
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// TODO: move this logic into the app?
let request_bytes = json_request.num_bytes();
let request_metadata =
Arc::new(RequestMetadata::new(REQUEST_PERIOD, request_bytes).unwrap());
let subscription_id = json_request.params.unwrap().to_string();
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// TODO: is this the right response?
let partial_response = match subscriptions.remove(&subscription_id) {
None => false,
Some(handle) => {
handle.abort();
true
}
};
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let response =
JsonRpcForwardedResponse::from_value(json!(partial_response), id.clone());
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if let Some(stat_sender) = app.stat_sender.as_ref() {
let response_stat = ProxyResponseStat::new(
json_request.method.clone(),
authorization.clone(),
request_metadata,
response.num_bytes(),
);
if let Err(err) = stat_sender.send_async(response_stat.into()).await {
// TODO: what should we do?
warn!("stat_sender failed during eth_unsubscribe: {:?}", err);
}
}
Ok(response.into())
}
_ => {
app.proxy_web3_rpc(authorization.clone(), json_request.into())
.await
}
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};
(id, response)
}
Err(err) => {
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// TODO: move this logic somewhere else and just set id to None here
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let id = RawValue::from_string("null".to_string()).expect("null can always be a value");
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(id, Err(err.into()))
}
};
let response_str = match response {
Ok(x) => serde_json::to_string(&x),
Err(err) => {
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// we have an anyhow error. turn it into a response
let response = JsonRpcForwardedResponse::from_anyhow_error(err, None, Some(id));
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serde_json::to_string(&response)
}
}
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// TODO: what error should this be?
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.unwrap();
Message::Text(response_str)
}
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async fn read_web3_socket(
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app: Arc<Web3ProxyApp>,
authorization: Arc<Authorization>,
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mut ws_rx: SplitStream<WebSocket>,
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response_sender: flume::Sender<Message>,
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) {
let mut subscriptions = HashMap::new();
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let subscription_count = AtomicUsize::new(1);
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while let Some(Ok(msg)) = ws_rx.next().await {
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// TODO: spawn this?
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// new message from our client. forward to a backend and then send it through response_tx
let response_msg = match msg {
Message::Text(payload) => {
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handle_socket_payload(
app.clone(),
&authorization,
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&payload,
&response_sender,
&subscription_count,
&mut subscriptions,
)
.await
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}
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Message::Ping(x) => {
trace!("ping: {:?}", x);
Message::Pong(x)
}
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Message::Pong(x) => {
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trace!("pong: {:?}", x);
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continue;
}
Message::Close(_) => {
info!("closing websocket connection");
break;
}
Message::Binary(mut payload) => {
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// TODO: poke rate limit for the user/ip
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let payload = from_utf8_mut(&mut payload).unwrap();
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handle_socket_payload(
app.clone(),
&authorization,
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payload,
&response_sender,
&subscription_count,
&mut subscriptions,
)
.await
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}
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};
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match response_sender.send_async(response_msg).await {
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Ok(_) => {}
Err(err) => {
error!("{}", err);
break;
}
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};
}
}
async fn write_web3_socket(
response_rx: flume::Receiver<Message>,
mut ws_tx: SplitSink<WebSocket, Message>,
) {
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// TODO: increment counter for open websockets
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// TODO: is there any way to make this stream receive.
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while let Ok(msg) = response_rx.recv_async().await {
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// a response is ready
// TODO: poke rate limits for this user?
// forward the response to through the websocket
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if let Err(err) = ws_tx.send(msg).await {
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// this is common. it happens whenever a client disconnects
trace!("unable to write to websocket: {:?}", err);
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break;
};
}
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// TODO: decrement counter for open websockets
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}