Fix panic when TURN server returns non-UTF-8 bytes in STUN error reason phrase

rtc-stun/src/error_code.rs

@@ -1,3 +1,6 @@
+#[cfg(test)]
+mod error_code_test;
+
 use crate::attributes::*;
 use crate::checks::*;
 use crate::message::*;
@@ -17,12 +20,7 @@ pub struct ErrorCodeAttribute {
 
 impl fmt::Display for ErrorCodeAttribute {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let reason = match String::from_utf8(self.reason.clone()) {
-            Ok(reason) => reason,
-            Err(_) => return Err(fmt::Error {}),
-        };
-
-        write!(f, "{}: {}", self.code.0, reason)
+        write!(f, "{}: {}", self.code.0, String::from_utf8_lossy(&self.reason))
     }
 }
 

rtc-stun/src/error_code/error_code_test.rs

@@ -0,0 +1,21 @@
+use super::*;
+
+#[test]
+fn test_display_valid_utf8() {
+    let code = ErrorCodeAttribute {
+        code: ErrorCode(401),
+        reason: b"Unauthorized".to_vec(),
+    };
+    assert_eq!(format!("{}", code), "401: Unauthorized");
+}
+
+#[test]
+fn test_display_invalid_utf8_does_not_panic() {
+    let code = ErrorCodeAttribute {
+        code: ErrorCode(401),
+        reason: vec![0xc0, 0xaf],
+    };
+    let result = format!("{}", code);
+    assert!(result.starts_with("401: "));
+    assert!(result.contains('\u{FFFD}'));
+}