feat(auth): Automatically find free port

* feat: add auth_port configuration option

Signed-off-by: Elias Assaf <elyas51000@gmail.com>

* feat(auth): Automatically find free port

---------

Signed-off-by: Elias Assaf <elyas51000@gmail.com>
Co-authored-by: Henrik Friedrichsen <henrik@affekt.org>

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Automatically find free port for OAuth2 login flow
+
 ### Fixed
 
 - Skip unplayable tracks

src/authentication.rs

@@ -1,3 +1,5 @@
+use std::net::TcpListener;
+
 use librespot_core::authentication::Credentials as RespotCredentials;
 use librespot_core::cache::Cache;
 use librespot_oauth::get_access_token;
@@ -7,7 +9,6 @@ use crate::config::{self, Config};
 use crate::spotify::Spotify;
 
 pub const SPOTIFY_CLIENT_ID: &str = "65b708073fc0480ea92a077233ca87bd";
-pub const CLIENT_REDIRECT_URI: &str = "http://127.0.0.1:8989/login";
 
 static OAUTH_SCOPES: &[&str] = &[
     "playlist-modify",
@@ -35,6 +36,20 @@ static OAUTH_SCOPES: &[&str] = &[
     "user-top-read",
 ];
 
+pub fn find_free_port() -> Result<u16, String> {
+    let socket = TcpListener::bind("127.0.0.1:0").map_err(|e| e.to_string())?;
+    socket
+        .local_addr()
+        .map(|addr| addr.port())
+        .map_err(|e| e.to_string())
+}
+
+pub fn get_client_redirect_uri() -> String {
+    let auth_port = find_free_port().expect("Could not find free port");
+    let redirect_url = format!("http://127.0.0.1:{auth_port}/login");
+    redirect_url
+}
+
 /// Get credentials for use with librespot. This first tries to get cached credentials. If no cached
 /// credentials are available it will initiate the OAuth2 login process.
 pub fn get_credentials(configuration: &Config) -> Result<RespotCredentials, String> {
@@ -73,7 +88,7 @@ pub fn create_credentials() -> Result<RespotCredentials, String> {
     println!("To login you need to perform OAuth2 authorization using your web browser\n");
     get_access_token(
         SPOTIFY_CLIENT_ID,
-        CLIENT_REDIRECT_URI,
+        &get_client_redirect_uri(),
         OAUTH_SCOPES.to_vec(),
     )
     .map(|token| RespotCredentials::with_access_token(token.access_token))