feat: add and remove subscriptions from client requests

A hashmap of active subscriptions is maintained for each client.  REQ
and CLOSE commands will modify the subscription list.

src/close.rs

@@ -2,20 +2,28 @@ use crate::error::{Error, Result};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Deserialize, PartialEq, Debug, Clone)]
-pub struct Close {
+pub struct CloseCmd {
     cmd: String,
     id: String,
 }
 
-impl Close {
-    pub fn parse(json: &str) -> Result<Close> {
-        let c: Close = serde_json::from_str(json)?; //.map_err(|e| Error::JsonParseFailed(e));
-        if c.cmd != "CLOSE" {
-            return Err(Error::CloseParseFailed);
-        }
-        return Ok(c);
+#[derive(Serialize, Deserialize, PartialEq, Debug, Clone)]
+pub struct Close {
+    id: String,
 }
 
+impl From<CloseCmd> for Result<Close> {
+    fn from(cc: CloseCmd) -> Result<Close> {
+        // ensure command is correct
+        if cc.cmd != "CLOSE" {
+            return Err(Error::CommandUnknownError);
+        } else {
+            return Ok(Close { id: cc.id });
+        }
+    }
+}
+
+impl Close {
     pub fn get_id(&self) -> String {
         self.id.clone()
     }

src/conn.rs

@@ -1,14 +1,21 @@
-//use std::collections::HashMap;
+use crate::close::Close;
+use crate::error::Result;
+use crate::subscription::Subscription;
+use log::*;
+use std::collections::HashMap;
 use uuid::Uuid;
 
+// subscription identifiers must be reasonably sized.
+const MAX_SUBSCRIPTION_ID_LEN: usize = 256;
+
 // state for a client connection
 pub struct ClientConn {
     _client_id: Uuid,
     // current set of subscriptions
-    //subscriptions: HashMap<String, Subscription>,
+    subscriptions: HashMap<String, Subscription>,
     // websocket
     //stream: WebSocketStream<TcpStream>,
-    _max_subs: usize,
+    max_subs: usize,
 }
 
 impl ClientConn {
@@ -16,7 +23,46 @@ impl ClientConn {
         let client_id = Uuid::new_v4();
         ClientConn {
             _client_id: client_id,
-            _max_subs: 128,
+            subscriptions: HashMap::new(),
+            max_subs: 128,
         }
     }
+
+    pub fn subscribe(&mut self, s: Subscription) -> Result<()> {
+        let k = s.get_id();
+        let sub_id_len = k.len();
+        if sub_id_len > MAX_SUBSCRIPTION_ID_LEN {
+            info!("Dropping subscription with huge ({}) length", sub_id_len);
+            return Ok(());
+        }
+        // check if an existing subscription exists, and replace if so
+        if self.subscriptions.contains_key(&k) {
+            self.subscriptions.remove(&k);
+            self.subscriptions.insert(k, s);
+            info!("Replaced existing subscription");
+            return Ok(());
+        }
+
+        // check if there is room for another subscription.
+        if self.subscriptions.len() >= self.max_subs {
+            info!("Client has reached the maximum number of unique subscriptions");
+            return Ok(());
+        }
+        // add subscription
+        self.subscriptions.insert(k, s);
+        info!(
+            "Registered new subscription, currently have {} active subs",
+            self.subscriptions.len()
+        );
+        return Ok(());
+    }
+
+    pub fn unsubscribe(&mut self, c: Close) {
+        // TODO: return notice if subscription did not exist.
+        self.subscriptions.remove(&c.get_id());
+        info!(
+            "Removed subscription, currently have {} active subs",
+            self.subscriptions.len()
+        );
+    }
 }

src/event.rs

@@ -16,7 +16,7 @@ pub struct EventCmd {
 
 #[derive(Serialize, Deserialize, PartialEq, Debug, Clone)]
 pub struct Event {
-    pub(crate) id: String,
+    pub id: String,
     pub(crate) pubkey: String,
     pub(crate) created_at: u64,
     pub(crate) kind: u64,

src/main.rs

@@ -1,5 +1,6 @@
 use futures::StreamExt;
 use log::*;
+use nostr_rs_relay::close::Close;
 use nostr_rs_relay::conn;
 use nostr_rs_relay::error::{Error, Result};
 use nostr_rs_relay::event::Event;
@@ -66,7 +67,7 @@ async fn nostr_server(
     //let task_queue = mpsc::channel::<NostrMessage>(16);
     // track connection state so we can break when it fails
     // Track internal client state
-    let _conn = conn::ClientConn::new();
+    let mut conn = conn::ClientConn::new();
     let mut conn_good = true;
     loop {
         tokio::select! {
@@ -77,22 +78,31 @@ async fn nostr_server(
                         // handle each type of message
                         let parsed : Result<Event> = Result::<Event>::from(ec);
                         match parsed {
-                            Ok(_) => {info!("Successfully parsed/validated event")},
+                            Ok(e) => {
+                                let id_prefix:String = e.id.chars().take(8).collect();
+                                info!("Successfully parsed/validated event: {}", id_prefix)},
                             Err(_) => {info!("Invalid event ignored")}
                         }
                     },
                     Some(Ok(SubMsg(s))) => {
-                        info!("Sub-open request from client: {:?}", s);
+                        // subscription handling consists of:
+                        // adding new subscriptions to the client conn:
+                        conn.subscribe(s).ok();
+                        // TODO: sending a request for a SQL query
                     },
-                    Some(Ok(CloseMsg(c))) => {
-                        info!("Sub-close request from client: {:?}", c);
+                    Some(Ok(CloseMsg(cc))) => {
+                        // closing a request simply removes the subscription.
+                        let parsed : Result<Close> = Result::<Close>::from(cc);
+                        match parsed {
+                            Ok(c) => {conn.unsubscribe(c);},
+                            Err(_) => {info!("Invalid command ignored");}
+                        }
                     },
                     None => {
                         info!("stream ended");
-                        //conn_good = true;
                     },
                     Some(Err(Error::ConnError)) => {
-                        info!("got connection error, disconnecting");
+                        debug!("got connection error, disconnecting");
                         conn_good = false;
                        if conn_good {
                            info!("Lint bug?, https://github.com/rust-lang/rust/pull/57302");
@@ -105,7 +115,7 @@ async fn nostr_server(
                 }
             }
         }
-        if conn_good == false {
+        if !conn_good {
             break;
         }
     }

src/protostream.rs

@@ -1,4 +1,4 @@
-use crate::close::Close;
+use crate::close::CloseCmd;
 use crate::error::{Error, Result};
 use crate::event::EventCmd;
 use crate::subscription::Subscription;
@@ -20,7 +20,7 @@ use tungstenite::protocol::Message;
 pub enum NostrMessage {
     EventMsg(EventCmd),
     SubMsg(Subscription),
-    CloseMsg(Close),
+    CloseMsg(CloseCmd),
 }
 
 // Either an event w/ subscription, or a notice