fix: allow arbitrary strings in subscription ids

crates/json-rpc/src/lib.rs

@@ -86,7 +86,7 @@ mod error;
 pub use error::RpcError;
 
 mod notification;
-pub use notification::{EthNotification, PubSubItem};
+pub use notification::{EthNotification, PubSubItem, SubId};
 
 mod packet;
 pub use packet::{BorrowedResponsePacket, RequestPacket, ResponsePacket};

crates/json-rpc/src/notification.rs

@@ -5,12 +5,22 @@ use serde::{
     Deserialize, Serialize,
 };
 
+/// A subscription ID.
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize, PartialOrd, Ord)]
+#[serde(untagged)]
+pub enum SubId {
+    /// A number.
+    Number(U256),
+    /// A string.
+    String(String),
+}
+
 /// An ethereum-style notification, not to be confused with a JSON-RPC
 /// notification.
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct EthNotification<T = Box<serde_json::value::RawValue>> {
     /// The subscription ID.
-    pub subscription: U256,
+    pub subscription: SubId,
     /// The notification payload.
     pub result: T,
 }
@@ -128,7 +138,7 @@ impl<'de> Deserialize<'de> for PubSubItem {
 #[cfg(test)]
 mod test {
 
-    use crate::{EthNotification, PubSubItem};
+    use crate::{EthNotification, PubSubItem, SubId};
 
     #[test]
     fn deserializer_test() {
@@ -140,7 +150,10 @@ mod test {
 
         match deser {
             PubSubItem::Notification(EthNotification { subscription, result }) => {
-                assert_eq!(subscription, "0xcd0c3e8af590364c09d0fa6a1210faf5".parse().unwrap());
+                assert_eq!(
+                    subscription,
+                    SubId::Number("0xcd0c3e8af590364c09d0fa6a1210faf5".parse().unwrap())
+                );
                 assert_eq!(result.get(), r#"{"difficulty": "0xd9263f42a87", "uncles": []}"#);
             }
             _ => panic!("unexpected deserialization result"),

crates/pubsub/src/managers/in_flight.rs

@@ -1,5 +1,4 @@
-use alloy_json_rpc::{Response, ResponsePayload, SerializedRequest};
-use alloy_primitives::U256;
+use alloy_json_rpc::{Response, ResponsePayload, SerializedRequest, SubId};
 use alloy_transport::{TransportError, TransportResult};
 use std::fmt;
 use tokio::sync::oneshot;
@@ -55,10 +54,10 @@ impl InFlight {
     /// Fulfill the request with a response. This consumes the in-flight
     /// request. If the request is a subscription and the response is not an
     /// error, the subscription ID and the in-flight request are returned.
-    pub(crate) fn fulfill(self, resp: Response) -> Option<(U256, Self)> {
+    pub(crate) fn fulfill(self, resp: Response) -> Option<(SubId, Self)> {
         if self.is_subscription() {
             if let ResponsePayload::Success(val) = resp.payload {
-                let sub_id: serde_json::Result<U256> = serde_json::from_str(val.get());
+                let sub_id: serde_json::Result<SubId> = serde_json::from_str(val.get());
                 return match sub_id {
                     Ok(alias) => Some((alias, self)),
                     Err(e) => {

crates/pubsub/src/managers/req.rs

@@ -1,6 +1,5 @@
 use crate::managers::InFlight;
-use alloy_json_rpc::{Id, Response};
-use alloy_primitives::U256;
+use alloy_json_rpc::{Id, Response, SubId};
 use std::collections::BTreeMap;
 
 /// Manages in-flight requests.
@@ -30,7 +29,7 @@ impl RequestManager {
     /// If the request created a new subscription, this function returns the
     /// subscription ID and the in-flight request for conversion to an
     /// `ActiveSubscription`.
-    pub(crate) fn handle_response(&mut self, resp: Response) -> Option<(U256, InFlight)> {
+    pub(crate) fn handle_response(&mut self, resp: Response) -> Option<(SubId, InFlight)> {
         if let Some(in_flight) = self.reqs.remove(&resp.id) {
             return in_flight.fulfill(resp);
         }

crates/pubsub/src/managers/sub.rs

@@ -1,14 +1,14 @@
 use crate::{managers::ActiveSubscription, RawSubscription};
-use alloy_json_rpc::{EthNotification, SerializedRequest};
-use alloy_primitives::{B256, U256};
+use alloy_json_rpc::{EthNotification, SerializedRequest, SubId};
+use alloy_primitives::B256;
 use bimap::BiBTreeMap;
 
 #[derive(Debug, Default)]
 pub(crate) struct SubscriptionManager {
     /// The subscriptions.
     local_to_sub: BiBTreeMap<B256, ActiveSubscription>,
     /// Tracks the CURRENT server id for a subscription.
-    local_to_server: BiBTreeMap<B256, U256>,
+    local_to_server: BiBTreeMap<B256, SubId>,
 }
 
 impl SubscriptionManager {
@@ -26,7 +26,7 @@ impl SubscriptionManager {
     fn insert(
         &mut self,
         request: SerializedRequest,
-        server_id: U256,
+        server_id: SubId,
         channel_size: usize,
     ) -> RawSubscription {
         let active = ActiveSubscription::new(request, channel_size);
@@ -43,7 +43,7 @@ impl SubscriptionManager {
     pub(crate) fn upsert(
         &mut self,
         request: SerializedRequest,
-        server_id: U256,
+        server_id: SubId,
         channel_size: usize,
     ) -> RawSubscription {
         let local_id = request.params_hash();
@@ -59,8 +59,8 @@ impl SubscriptionManager {
     }
 
     /// De-alias an alias, getting the original ID.
-    pub(crate) fn local_id_for(&self, server_id: U256) -> Option<B256> {
-        self.local_to_server.get_by_right(&server_id).copied()
+    pub(crate) fn local_id_for(&self, server_id: &SubId) -> Option<B256> {
+        self.local_to_server.get_by_right(server_id).copied()
     }
 
     /// Drop all server_ids.
@@ -69,7 +69,7 @@ impl SubscriptionManager {
     }
 
     /// Change the server_id of a subscription.
-    fn change_server_id(&mut self, local_id: B256, server_id: U256) {
+    fn change_server_id(&mut self, local_id: B256, server_id: SubId) {
         self.local_to_server.insert(local_id, server_id);
     }
 
@@ -83,7 +83,7 @@ impl SubscriptionManager {
     /// and if any receiver exists. If the sub id is unknown, or no receiver
     /// exists, the notification is dropped.
     pub(crate) fn notify(&mut self, notification: EthNotification) {
-        if let Some(local_id) = self.local_id_for(notification.subscription) {
+        if let Some(local_id) = self.local_id_for(&notification.subscription) {
             if let Some((_, mut sub)) = self.local_to_sub.remove_by_left(&local_id) {
                 sub.notify(notification.result);
                 self.local_to_sub.insert(local_id, sub);

crates/pubsub/src/service.rs

@@ -4,7 +4,7 @@ use crate::{
     managers::{InFlight, RequestManager, SubscriptionManager},
     PubSubConnect, PubSubFrontend, RawSubscription,
 };
-use alloy_json_rpc::{Id, PubSubItem, Request, Response, ResponsePayload};
+use alloy_json_rpc::{Id, PubSubItem, Request, Response, ResponsePayload, SubId};
 use alloy_primitives::U256;
 use alloy_transport::{
     utils::{to_json_raw_value, Spawnable},
@@ -167,16 +167,18 @@ impl<T: PubSubConnect> PubSubService<T> {
     }
 
     /// Rewrite the subscription id and insert into the subscriptions manager
-    fn handle_sub_response(&mut self, in_flight: InFlight, server_id: U256) -> TransportResult<()> {
+    fn handle_sub_response(
+        &mut self,
+        in_flight: InFlight,
+        server_id: SubId,
+    ) -> TransportResult<()> {
         let request = in_flight.request;
         let id = request.id().clone();
 
-        self.subs.upsert(request, server_id, in_flight.channel_size);
+        let sub = self.subs.upsert(request, server_id, in_flight.channel_size);
 
-        // lie to the client about the sub id.
-        let local_id = self.subs.local_id_for(server_id).unwrap();
         // Serialized B256 is always a valid serialized U256 too.
-        let ser_alias = to_json_raw_value(&local_id)?;
+        let ser_alias = to_json_raw_value(sub.local_id())?;
 
         // We send back a success response with the new subscription ID.
         // We don't care if the channel is dead.