fix inverted split for DATA frame padding (#330)

src/frame/data.rs

@@ -63,6 +63,18 @@ impl<T> Data<T> {
         }
     }
 
+    /// Returns whther the `PADDED` flag is set on this frame.
+    #[cfg(feature = "unstable")]
+    pub fn is_padded(&self) -> bool {
+        self.flags.is_padded()
+    }
+
+    /// Sets the value for the `PADDED` flag on this frame.
+    #[cfg(feature = "unstable")]
+    pub fn set_padded(&mut self) {
+        self.flags.set_padded();
+    }
+
     /// Returns a reference to this frame's payload.
     ///
     /// This does **not** include any padding that might have been originally
@@ -192,6 +204,11 @@ impl DataFlags {
     fn is_padded(&self) -> bool {
         self.0 & PADDED == PADDED
     }
+
+    #[cfg(feature = "unstable")]
+    fn set_padded(&mut self) {
+        self.0 |= PADDED
+    }
 }
 
 impl Default for DataFlags {

src/frame/util.rs

@@ -15,7 +15,8 @@ use bytes::Bytes;
 /// If the padded payload is invalid (e.g. the length of the padding is equal
 /// to the total length), returns `None`.
 pub fn strip_padding(payload: &mut Bytes) -> Result<u8, Error> {
-    if payload.len() == 0 {
+    let payload_len = payload.len();
+    if payload_len == 0 {
         // If this is the case, the frame is invalid as no padding length can be
         // extracted, even though the frame should be padded.
         return Err(Error::TooMuchPadding);
@@ -23,14 +24,14 @@ pub fn strip_padding(payload: &mut Bytes) -> Result<u8, Error> {
 
     let pad_len = payload[0] as usize;
 
-    if pad_len >= payload.len() {
+    if pad_len >= payload_len {
         // This is invalid: the padding length MUST be less than the
         // total frame size.
         return Err(Error::TooMuchPadding);
     }
 
     let _ = payload.split_to(1);
-    let _ = payload.split_off(pad_len);
+    let _ = payload.split_off(payload_len - pad_len - 1);
 
     Ok(pad_len as u8)
 }