handling client_id scoping for Spotify Connect feature with librespot 0.5.0 (#584)

- update `token::get_token` to support user-provided `client_id` (required for Spotify Connect feature)
- refactor playback initialization logic upon startup or new session

Author: aome510

spotify_player/src/auth.rs

@@ -5,15 +5,18 @@ use librespot_oauth::get_access_token;
 use crate::config;
 
 pub const SPOTIFY_CLIENT_ID: &str = "65b708073fc0480ea92a077233ca87bd";
-pub const CLIENT_REDIRECT_URI: &str = "http://127.0.0.1:8989/login";
-pub const OAUTH_SCOPES: &[&str] = &[
+const CLIENT_REDIRECT_URI: &str = "http://127.0.0.1:8989/login";
+// based on https://github.com/librespot-org/librespot/blob/f96f36c064795011f9fee912291eecb1aa46fff6/src/main.rs#L173
+const OAUTH_SCOPES: &[&str] = &[
+    "app-remote-control",
     "playlist-modify",
     "playlist-modify-private",
     "playlist-modify-public",
     "playlist-read",
     "playlist-read-collaborative",
     "playlist-read-private",
     "streaming",
+    "ugc-image-upload",
     "user-follow-modify",
     "user-follow-read",
     "user-library-modify",
@@ -22,6 +25,7 @@ pub const OAUTH_SCOPES: &[&str] = &[
     "user-modify-playback-state",
     "user-modify-private",
     "user-personalized",
+    "user-read-birthdate",
     "user-read-currently-playing",
     "user-read-email",
     "user-read-play-history",

spotify_player/src/client/mod.rs

@@ -60,22 +60,55 @@ impl Client {
     }
 
     /// Initialize the application's playback upon creating a new session or during startup
-    pub async fn initialize_playback(&self, state: &SharedState) -> Result<()> {
-        self.retrieve_current_playback(state, false).await?;
-
-        if state.player.read().playback.is_none() {
-            tracing::info!("No playback found, trying to connect to an available device...");
-            // // handle `connect_device` task separately as we don't want to block here
-            tokio::task::spawn({
-                let client = self.clone();
-                let state = state.clone();
-                async move {
-                    client.connect_device(&state).await;
-                }
-            });
-        }
+    pub fn initialize_playback(&self, state: &SharedState) {
+        tokio::task::spawn({
+            let client = self.clone();
+            let state = state.clone();
+            async move {
+                // The main playback initialization logic is simple:
+                // if there is no playback, connect to an available device
+                //
+                // However, because it takes time for Spotify server to show up new changes,
+                // a retry logic is implemented to ensure the application's state is properly initialized
+                let delay = std::time::Duration::from_secs(1);
+
+                for _ in 0..5 {
+                    tokio::time::sleep(delay).await;
+
+                    if let Err(err) = client.retrieve_current_playback(&state, false).await {
+                        tracing::error!("Failed to retrieve current playback: {err:#}");
+                        return;
+                    }
 
-        Ok(())
+                    // if playback exists, don't connect to a new device
+                    if state.player.read().playback.is_some() {
+                        continue;
+                    }
+
+                    let id = match client.find_available_device().await {
+                        Ok(Some(id)) => Some(Cow::Owned(id)),
+                        Ok(None) => None,
+                        Err(err) => {
+                            tracing::error!("Failed to find an available device: {err:#}");
+                            None
+                        }
+                    };
+
+                    if let Some(id) = id {
+                        tracing::info!("Trying to connect to device (id={id})");
+                        if let Err(err) = client.transfer_playback(&id, Some(false)).await {
+                            tracing::warn!("Connection failed (device_id={id}): {err:#}");
+                        } else {
+                            tracing::info!("Connection succeeded (device_id={id})!");
+                            // upon new connection, reset the buffered playback
+                            state.player.write().buffered_playback = None;
+                            client.update_playback(&state);
+                            break;
+                        }
+                    }
+                }
+            }
+        });
     }
 
     /// Create a new client session
@@ -114,10 +147,7 @@ impl Client {
         if let Some(state) = state {
             // reset the application's caches
             state.data.write().caches = MemoryCaches::new();
-
-            self.initialize_playback(state)
-                .await
-                .context("initialize playback")?;
+            self.initialize_playback(state);
         }
 
         Ok(())
@@ -554,40 +584,6 @@ impl Client {
         Ok(())
     }
 
-    /// Connect to a Spotify device
-    async fn connect_device(&self, state: &SharedState) {
-        // Device connection can fail when the specified device hasn't shown up
-        // in the Spotify's server, resulting in a failed `TransferPlayback` API request.
-        // This is why a retry mechanism is needed to ensure a successful connection.
-        let delay = std::time::Duration::from_secs(1);
-
-        for _ in 0..10 {
-            tokio::time::sleep(delay).await;
-
-            let id = match self.find_available_device().await {
-                Ok(Some(id)) => Some(Cow::Owned(id)),
-                Ok(None) => None,
-                Err(err) => {
-                    tracing::error!("Failed to find an available device: {err:#}");
-                    None
-                }
-            };
-
-            if let Some(id) = id {
-                tracing::info!("Trying to connect to device (id={id})");
-                if let Err(err) = self.transfer_playback(&id, Some(false)).await {
-                    tracing::warn!("Connection failed (device_id={id}): {err:#}");
-                } else {
-                    tracing::info!("Connection succeeded (device_id={id})!");
-                    // upon new connection, reset the buffered playback
-                    state.player.write().buffered_playback = None;
-                    self.update_playback(state);
-                    break;
-                }
-            }
-        }
-    }
-
     pub fn update_playback(&self, state: &SharedState) {
         // After handling a request changing the player's playback,
         // update the playback state by making multiple get-playback requests.

spotify_player/src/client/spotify.rs

@@ -9,7 +9,7 @@ use rspotify::{
 };
 use std::{fmt, sync::Arc};
 
-use crate::token;
+use crate::{config, token};
 
 #[derive(Clone, Default)]
 /// A Spotify client to interact with Spotify API server
@@ -19,6 +19,7 @@ pub struct Spotify {
     config: Config,
     token: Arc<Mutex<Option<Token>>>,
     http: HttpClient,
+    client_id: String,
     pub(crate) session: Arc<tokio::sync::Mutex<Option<Session>>>,
 }
 
@@ -45,6 +46,12 @@ impl Spotify {
             },
             token: Arc::new(Mutex::new(None)),
             http: HttpClient::default(),
+            // Spotify client uses different `client_id` from Spotify session (`auth::SPOTIFY_CLIENT_ID`)
+            // to support user-provided `client_id`, which is required for Spotify Connect feature
+            client_id: config::get_config()
+                .app_config
+                .get_client_id()
+                .expect("get client_id"),
             session: Arc::new(tokio::sync::Mutex::new(None)),
         }
     }
@@ -108,7 +115,7 @@ impl BaseClient for Spotify {
             return Ok(old_token);
         }
 
-        match token::get_token(&session).await {
+        match token::get_token(&session, &self.client_id).await {
             Ok(token) => Ok(Some(token)),
             Err(err) => {
                 tracing::error!("Failed to get a new token: {err:#}");

spotify_player/src/config/mod.rs

@@ -413,8 +413,6 @@ impl AppConfig {
     }
 
     /// Returns stdout of `client_id_command` if set, otherwise it returns the the value of `client_id`
-    // TODO: figure out how to use user-provided client_id for Spotify Connect integration
-    #[allow(dead_code)]
     pub fn get_client_id(&self) -> Result<String> {
         match self.client_id_command {
             Some(ref cmd) => cmd.execute(None),

spotify_player/src/main.rs

@@ -23,10 +23,7 @@ async fn init_spotify(
     client: &client::Client,
     state: &state::SharedState,
 ) -> Result<()> {
-    client
-        .initialize_playback(state)
-        .await
-        .context("initialize playback")?;
+    client.initialize_playback(state);
 
     // request user data
     client_pub.send(client::ClientRequest::GetCurrentUser)?;

spotify_player/src/token.rs

@@ -3,17 +3,53 @@ use std::collections::HashSet;
 use anyhow::Result;
 use chrono::{Duration, Utc};
 use librespot_core::session::Session;
-use rspotify::Token;
-
-use crate::auth::OAUTH_SCOPES;
 
 const TIMEOUT_IN_SECS: u64 = 5;
 
-pub async fn get_token(session: &Session) -> Result<Token> {
+/// The application authentication token's permission scopes
+const SCOPES: [&str; 15] = [
+    "user-read-recently-played",
+    "user-top-read",
+    "user-read-playback-position",
+    "user-read-playback-state",
+    "user-modify-playback-state",
+    "user-read-currently-playing",
+    "streaming",
+    "playlist-read-private",
+    "playlist-modify-private",
+    "playlist-modify-public",
+    "playlist-read-collaborative",
+    "user-follow-read",
+    "user-follow-modify",
+    "user-library-read",
+    "user-library-modify",
+];
+
+async fn retrieve_token(
+    session: &Session,
+    client_id: &str,
+) -> Result<librespot_core::token::Token> {
+    let query_uri = format!(
+        "hm://keymaster/token/authenticated?scope={}&client_id={}&device_id={}",
+        SCOPES.join(","),
+        client_id,
+        session.device_id(),
+    );
+    let request = session.mercury().get(query_uri)?;
+    let response = request.await?;
+    let data = response
+        .payload
+        .first()
+        .ok_or(librespot_core::token::TokenError::Empty)?
+        .to_vec();
+    let token = librespot_core::token::Token::from_json(String::from_utf8(data)?)?;
+    Ok(token)
+}
+
+pub async fn get_token(session: &Session, client_id: &str) -> Result<rspotify::Token> {
     tracing::info!("Getting a new authentication token...");
 
-    let scopes = OAUTH_SCOPES.join(",");
-    let fut = session.token_provider().get_token(&scopes);
+    let fut = retrieve_token(session, client_id);
     let token =
         match tokio::time::timeout(std::time::Duration::from_secs(TIMEOUT_IN_SECS), fut).await {
             Ok(Ok(token)) => token,
@@ -34,7 +70,7 @@ pub async fn get_token(session: &Session) -> Result<Token> {
     // let expires_in = Duration::from_std(std::time::Duration::from_secs(5))?;
     let expires_at = Utc::now() + expires_in;
 
-    let token = Token {
+    let token = rspotify::Token {
         access_token: token.access_token,
         expires_in,
         expires_at: Some(expires_at),