feat(peer): ask a peer what it says about itself

The client answered a UserInfoRequest but could never send one, so a
user's profile — description, upload slots, queue length — was something
this client served and never saw. The reply (peer code 16) is now parsed
too, with the tolerances other clients carry: a picture is skipped rather
than kept, a length that overruns the message is clamped, and a message
that stops early (older clients, and Museek+ writing a boolean as an
integer) still yields every field before it.

soulseek-rs-lib/src/client/mod.rs

@@ -340,6 +340,11 @@ pub enum ClientOperation {
         token: u32,
         folder: String,
     },
+    /// A peer answered our request for what it says about itself.
+    PeerInfoReceived {
+        username: String,
+        info: crate::message::peer::PeerInfo,
+    },
     /// A peer answered our request for one folder of their shares.
     FolderContents {
         username: String,
@@ -494,6 +499,8 @@ pub struct ClientContext {
     browse_results: HashMap<String, Vec<SharedDirectory>>,
     /// One-folder listings received from peers, keyed by peer and folder.
     folder_contents: HashMap<(String, String), Vec<SharedDirectory>>,
+    /// What peers said about themselves (peer code 16), keyed by peer.
+    peer_infos: HashMap<String, crate::message::peer::PeerInfo>,
     pending_browses: HashMap<String, Instant>,
     /// Latest snapshot of the public chat-room list (from `RoomList`, code 64).
     room_list: Vec<RoomInfo>,
@@ -651,6 +658,7 @@ impl ClientContext {
             pending_serves: HashMap::new(),
             browse_results: HashMap::new(),
             folder_contents: HashMap::new(),
+            peer_infos: HashMap::new(),
             pending_browses: HashMap::new(),
             room_list: Vec::new(),
             room_events: Vec::new(),
@@ -863,6 +871,30 @@ impl ClientContext {
         }
     }
 
+    /// Record what `username` says about itself.
+    pub fn store_peer_info(
+        &mut self,
+        username: String,
+        info: crate::message::peer::PeerInfo,
+    ) {
+        self.peer_infos.insert(username, info);
+    }
+
+    /// What `username` last said about itself, if anything.
+    #[must_use]
+    pub fn peer_info(
+        &self,
+        username: &str,
+    ) -> Option<crate::message::peer::PeerInfo> {
+        self.peer_infos.get(username).cloned()
+    }
+
+    /// Drop what we hold about `username`, so a poll after a fresh request
+    /// cannot report the previous answer.
+    pub fn invalidate_peer_info(&mut self, username: &str) {
+        self.peer_infos.remove(username);
+    }
+
     /// Record one folder's listing from `username`.
     pub fn store_folder_contents(
         &mut self,

soulseek-rs-lib/src/client/operations.rs

@@ -919,6 +919,11 @@ impl Client {
                             }
                         }
                     }
+                    ClientOperation::PeerInfoReceived { username, info } => {
+                        if let Ok(mut ctx) = client_context.write_safe() {
+                            ctx.store_peer_info(username, info);
+                        }
+                    }
                     ClientOperation::FolderContents {
                         username,
                         token,

soulseek-rs-lib/src/client/social.rs

@@ -166,6 +166,34 @@ impl Client {
         ))
     }
 
+    /// Ask `username` what it says about itself (peer code 15): its
+    /// description, upload slots and queue length — a user's profile as other
+    /// clients show it.
+    ///
+    /// Any previous answer is dropped first, so [`Client::peer_info`] reports
+    /// the reply to this request rather than a stale one.
+    ///
+    /// # Errors
+    /// [`crate::SoulseekRs::NotConnected`] when there is no server connection,
+    /// or [`crate::SoulseekRs::LockPoisoned`] if the client state is poisoned.
+    pub fn request_peer_info(&self, username: &str) -> Result<()> {
+        self.context.write_safe()?.invalidate_peer_info(username);
+        let request = crate::message::peer::build_user_info_request();
+        self.send_to_peer_or_queue(username, request)
+    }
+
+    /// What `username` last said about itself.
+    #[must_use]
+    pub fn peer_info(
+        &self,
+        username: &str,
+    ) -> Option<crate::message::peer::PeerInfo> {
+        self.context
+            .read_safe()
+            .ok()
+            .and_then(|ctx| ctx.peer_info(username))
+    }
+
     /// Ask `username` for the contents of one folder of their shares (peer
     /// code 36) — what "download folder" in other clients asks for, without
     /// pulling their whole listing.