fn decrypt_check()

in neqo-crypto/src/aead_null.rs [60:80]

16 lines of code
6 McCabe index (conditional complexity)


    fn decrypt_check(&self, _count: u64, _aad: &[u8], input: &[u8]) -> Res<usize> {
        if input.len() < self.expansion() {
            return Err(Error::from(SEC_ERROR_BAD_DATA));
        }

        let len_encrypted = input
            .len()
            .checked_sub(self.expansion())
            .ok_or_else(|| Error::from(SEC_ERROR_BAD_DATA))?;
        // Check that:
        // 1) expansion is all zeros and
        // 2) if the encrypted data is also supplied that at least some values are no zero
        //    (otherwise padding will be interpreted as a valid packet)
        if &input[len_encrypted..] == AEAD_NULL_TAG
            && (len_encrypted == 0 || input[..len_encrypted].iter().any(|x| *x != 0x0))
        {
            Ok(len_encrypted)
        } else {
            Err(Error::from(SEC_ERROR_BAD_DATA))
        }
    }