feat: broadcast events that match active client subscriptions

A broadcast channel sends messages to all connections.  Any connection
with a subscription that matches then sends it via websocket.

src/conn.rs

@@ -1,5 +1,6 @@
 use crate::close::Close;
 use crate::error::Result;
+use crate::event::Event;
 use crate::subscription::Subscription;
 use log::*;
 use std::collections::HashMap;
@@ -10,7 +11,7 @@ const MAX_SUBSCRIPTION_ID_LEN: usize = 256;
 
 // state for a client connection
 pub struct ClientConn {
-    _client_id: Uuid,
+    client_id: Uuid,
     // current set of subscriptions
     subscriptions: HashMap<String, Subscription>,
     // websocket
@@ -22,12 +23,26 @@ impl ClientConn {
     pub fn new() -> Self {
         let client_id = Uuid::new_v4();
         ClientConn {
-            _client_id: client_id,
+            client_id: client_id,
             subscriptions: HashMap::new(),
             max_subs: 128,
         }
     }
 
+    pub fn get_client_prefix(&self) -> String {
+        self.client_id.to_string().chars().take(8).collect()
+    }
+
+    // return the first subscription that matches the event.
+    pub fn get_matching_subscription(&self, e: &Event) -> Option<&str> {
+        for (id, sub) in self.subscriptions.iter() {
+            if sub.interested_in_event(e) {
+                return Some(id);
+            }
+        }
+        None
+    }
+
     pub fn subscribe(&mut self, s: Subscription) -> Result<()> {
         let k = s.get_id();
         let sub_id_len = k.len();

src/event.rs

@@ -52,6 +52,11 @@ impl From<EventCmd> for Result<Event> {
 }
 
 impl Event {
+    // get short event identifer
+    pub fn get_event_id_prefix(&self) -> String {
+        self.id.chars().take(8).collect()
+    }
+
     // check if this event is valid (should be propagated, stored) based on signature.
     fn is_valid(&self) -> bool {
         // validation is performed by:

src/main.rs

@@ -1,3 +1,4 @@
+use futures::SinkExt;
 use futures::StreamExt;
 use log::*;
 use nostr_rs_relay::close::Close;
@@ -6,6 +7,7 @@ use nostr_rs_relay::error::{Error, Result};
 use nostr_rs_relay::event::Event;
 use nostr_rs_relay::protostream;
 use nostr_rs_relay::protostream::NostrMessage::*;
+use nostr_rs_relay::protostream::NostrResponse::*;
 use rusqlite::Result as SQLResult;
 use std::env;
 use tokio::net::{TcpListener, TcpStream};
@@ -59,7 +61,7 @@ async fn nostr_server(
 ) {
     // get a broadcast channel for clients to communicate on
     // wrap the TCP stream in a websocket.
-    let mut _bcast_rx = broadcast.subscribe();
+    let mut bcast_rx = broadcast.subscribe();
     let conn = tokio_tungstenite::accept_async(stream).await;
     let ws_stream = conn.expect("websocket handshake error");
     // a stream & sink of Nostr protocol messages
@@ -71,6 +73,26 @@ async fn nostr_server(
     let mut conn_good = true;
     loop {
         tokio::select! {
+            Ok(global_event) = bcast_rx.recv() => {
+                // ignoring closed broadcast errors, there will always be one sender available.
+                // Is there a subscription for this event?
+                let sub_name_opt = conn.get_matching_subscription(&global_event);
+                if sub_name_opt.is_none() {
+                    return;
+                } else {
+                    let sub_name = sub_name_opt.unwrap();
+                    let event_str = serde_json::to_string(&global_event);
+                    if event_str.is_ok() {
+                        info!("sub match: client: {}, sub: {}, event: {}",
+                              conn.get_client_prefix(), sub_name,
+                              global_event.get_event_id_prefix());
+                        // create an event response and send it
+                        let res = EventRes(sub_name.to_owned(),event_str.unwrap());
+                        nostr_stream.send(res).await.ok();
+                    }
+                }
+            },
+            // check if this client has a subscription
             proto_next = nostr_stream.next() => {
                 match proto_next {
                     Some(Ok(EventMsg(ec))) => {
@@ -80,7 +102,13 @@ async fn nostr_server(
                         match parsed {
                             Ok(e) => {
                                 let id_prefix:String = e.id.chars().take(8).collect();
-                                info!("Successfully parsed/validated event: {}", id_prefix)},
+                                info!("Successfully parsed/validated event: {}", id_prefix);
+                                // send this event to everyone listening.
+                                let bcast_res = broadcast.send(e);
+                                if bcast_res.is_err() {
+                                    warn!("Could not send broadcast message: {:?}", bcast_res);
+                                }
+                            },
                             Err(_) => {info!("Invalid event ignored")}
                         }
                     },

src/protostream.rs

@@ -25,8 +25,10 @@ pub enum NostrMessage {
 
 // Either an event w/ subscription, or a notice
 #[derive(Deserialize, Serialize, Clone, PartialEq, Debug)]
-enum NostrResponse {
-    Notice(String),
+pub enum NostrResponse {
+    NoticeRes(String),
+    // A subscription identifier and serialized response
+    EventRes(String, String),
 }
 
 // A Nostr protocol stream is layered on top of a Websocket stream.
@@ -84,8 +86,20 @@ impl Sink<NostrResponse> for NostrStream {
     }
 
     fn start_send(mut self: Pin<&mut Self>, item: NostrResponse) -> Result<(), Self::Error> {
-        let res_message = serde_json::to_string(&item).expect("Could convert message to string");
-        match Pin::new(&mut self.ws_stream).start_send(Message::Text(res_message)) {
+        //let res_message = serde_json::to_string(&item).expect("Could convert message to string");
+        // create the string to send.
+        // TODO: do real escaping for both of these.  Currently output isn't correctly escaped.
+        let send_str = match item {
+            NostrResponse::NoticeRes(msg) => {
+                let s = msg.replace("\"", "");
+                format!("[\"NOTICE\",\"{}\"]", s)
+            }
+            NostrResponse::EventRes(sub, eventstr) => {
+                let subesc = sub.replace("\"", "");
+                format!("[\"EVENT\",\"{}\",{}]", subesc, eventstr)
+            }
+        };
+        match Pin::new(&mut self.ws_stream).start_send(Message::Text(send_str)) {
             Ok(()) => Ok(()),
             Err(_) => Err(Error::ConnWriteError),
         }