fix fix Frame::is_parsable

src/frame.rs

@@ -161,17 +161,21 @@ fn seek_newline(cursor: &mut Cursor<&[u8]>) -> anyhow::Result<usize, RedisProtoc
 fn has_crlf_with_checks(cursor: &mut Cursor<&[u8]>) -> anyhow::Result<(), RedisProtocolError> {
     while cursor.has_remaining() {
         let byte = cursor.get_u8();
+        let has_remaining = cursor.has_remaining();
         if byte == b'\r' {
-            if cursor.has_remaining() {
+            if has_remaining {
                 if cursor.get_u8() == b'\n' {
                     return Ok(());
                 }
             } else {
+                // We might get the missing byte later
                 return Err(RedisProtocolError::NotEnoughData);
             }
+            // Delimiter must be `\r\n`
             return Err(RedisProtocolError::ExcessiveNewline);
         }
-        if byte == b'\n' && cursor.has_remaining() && cursor.get_u8() != b'\r' {
+        if byte == b'\n' && has_remaining {
+            // Early return if there is an extra newline character (delimiter must be `\r\n`)
             return Err(RedisProtocolError::ExcessiveNewline);
         }
     }

tests/frame.rs

@@ -181,6 +181,34 @@ mod tests {
         assert!(Frame::is_parsable(&mut cursor).is_ok(), "Expected Ok");
     }
 
+    #[test]
+    fn incorrect_delimiter_in_simple_string() {
+        let data = b"+Hello from LFCR\n\r";
+        let mut cursor = Cursor::new(&data[..]);
+
+        assert!(
+            matches!(
+                Frame::is_parsable(&mut cursor),
+                Err(RedisProtocolError::ExcessiveNewline)
+            ),
+            "Expected ExcessiveNewline"
+        );
+    }
+
+    #[test]
+    fn incorrect_delimiter_in_bulk_string() {
+        let data = b"$3\nabc\n\r";
+        let mut cursor = Cursor::new(&data[..]);
+
+        assert!(
+            matches!(
+                Frame::is_parsable(&mut cursor),
+                Err(RedisProtocolError::NotEnoughData)
+            ),
+            "Expected NotEnoughData"
+        );
+    }
+
     #[test]
     fn test_null_bulk_string() {
         get_or_init_logger();