Revert "removed check for client ids"

This reverts commit 17f67b6.

src/async_client.rs

@@ -93,9 +93,20 @@ impl AsyncClient {
     pub async fn validate_id_token<S>(&self, token: S) -> MyResult<GooglePayload>
         where S: AsRef<str>
     {
-        let token = token.as_ref();
+        // fast check:
+        // if there is no given client id, simple return without communicating with Google server.
+
         let client_ids = self.client_ids.read().await;
 
+        if client_ids.is_empty() {
+            return Err(Error::IDTokenClientIDNotFoundError(IDTokenClientIDNotFoundError {
+                get: token.as_ref().to_string(),
+                expected: Default::default(),
+            }))
+        }
+
+        let token = token.as_ref();
+
         let parser: JwtParser<GooglePayload> = JwtParser::parse(token)?;
 
         id_token::validate_info(&*client_ids, &parser)?;

src/validate/id_token.rs

@@ -19,7 +19,7 @@ pub fn validate_info<T, V>(client_ids: T, parser: &JwtParser<GooglePayload>) ->
         T: AsRef<[V]>,
         V: AsRef<str>,
 {
-    if !client_ids.as_ref().is_empty() && !client_ids.as_ref().iter().any(|c| c.as_ref() == parser.payload.aud.as_str()) {
+    if !client_ids.as_ref().iter().any(|c| c.as_ref() == parser.payload.aud.as_str()) {
         // bail!("id_token: audience provided does not match aud claim in the jwt");
         Err(IDTokenClientIDNotFoundError::new(&parser.payload.aud, client_ids))?
     }