Don't panic if chunked encoding contains no chunk length

src/response.rs

@@ -482,14 +482,13 @@ where
                     return Err(Error::Codec);
                 }
             } else {
+                if total_read == 0 || header_buf[total_read - 1] != b'\r' {
+                    return Err(Error::Codec);
+                }
                 break 'read_size;
             }
         }
 
-        if header_buf[total_read - 1] != b'\r' {
-            return Err(Error::Codec);
-        }
-
         let hex_digits = total_read - 1;
 
         // Prepend hex with zeros
@@ -687,6 +686,7 @@ mod tests {
         reader::BufferingReader,
         request::Method,
         response::{ChunkState, ChunkedBodyReader, Response},
+        Error,
     };
 
     #[tokio::test]
@@ -727,6 +727,21 @@ mod tests {
         assert_eq!(11, response.body().discard().await.unwrap());
     }
 
+    #[tokio::test]
+    async fn incorrect_fragment_length_does_not_panic() {
+        let mut response =
+            b"HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n\n\r\nHELLO WORLD\r\n0\r\n\r\n".as_slice();
+        let mut header_buf = [0; 200];
+
+        let response = Response::read(&mut response, Method::GET, &mut header_buf)
+            .await
+            .unwrap();
+
+        let error = response.body().read_to_end().await.unwrap_err();
+
+        assert!(matches!(error, Error::Codec))
+    }
+
     #[tokio::test]
     async fn can_read_with_chunked_encoding() {
         let mut response =