fix: panic on invalid dynamic size message

src/decoder.rs

@@ -359,7 +359,7 @@ impl<'a> Decoder<'a> {
                 },
                 FieldRepresentation::SizeUpdate => {
                     // Handle the dynamic table size update...
-                    self.update_max_dynamic_size(buffer_leftover)
+                    self.update_max_dynamic_size(buffer_leftover)?
                 }
             };
 
@@ -445,19 +445,16 @@ impl<'a> Decoder<'a> {
     /// size of the underlying dynamic table, possibly causing a number of
     /// headers to be evicted from it.
     ///
-    /// Assumes that the first byte in the given buffer `buf` is the first
-    /// octet in the `SizeUpdate` block.
-    ///
     /// Returns the number of octets consumed from the given buffer.
-    fn update_max_dynamic_size(&mut self, buf: &[u8]) -> usize {
-        let (new_size, consumed) = decode_integer(buf, 5).ok().unwrap();
+    fn update_max_dynamic_size(&mut self, buf: &[u8]) -> Result<usize, DecoderError> {
+        let (new_size, consumed) = decode_integer(buf, 5)?;
         self.header_table.dynamic_table.set_max_table_size(new_size);
 
         info!("Decoder changed max table size from {} to {}",
               self.header_table.dynamic_table.get_size(),
               new_size);
 
-        consumed
+        Ok(consumed)
     }
 }
 
@@ -1351,6 +1348,13 @@ mod tests {
             _ => false,
         });
     }
+
+    #[test]
+    fn test_invalid_dynamic_size_update() {
+        let mut decoder = Decoder::new();
+        let hex_dump = &[0x3f];
+        let _ = decoder.decode(hex_dump);
+    }
 }
 
 /// The module defines interop tests between this HPACK decoder