fn open_combined_randnonce()

in aws-lc-rs/src/aead/unbound_key.rs [254:296]
35 lines of code
2 McCabe index (conditional complexity)

    fn open_combined_randnonce(
        &self,
        nonce: Nonce,
        aad: &[u8],
        in_out: &mut [u8],
    ) -> Result<(), Unspecified> {
        let nonce = nonce.as_ref();

        let alg_nonce_len = self.algorithm().nonce_len();
        let alg_tag_len = self.algorithm().tag_len();

        debug_assert_eq!(nonce.len(), alg_nonce_len);
        debug_assert!(alg_tag_len + alg_nonce_len <= MAX_TAG_NONCE_BUFFER_LEN);

        let plaintext_len = in_out.len() - alg_tag_len;

        let mut tag_buffer = [0u8; MAX_TAG_NONCE_BUFFER_LEN];

        tag_buffer[..alg_tag_len]
            .copy_from_slice(&in_out[plaintext_len..plaintext_len + alg_tag_len]);
        tag_buffer[alg_tag_len..alg_tag_len + alg_nonce_len].copy_from_slice(nonce);

        let tag_slice = &tag_buffer[0..alg_tag_len + alg_nonce_len];

        if 1 != indicator_check!(unsafe {
            EVP_AEAD_CTX_open_gather(
                *self.ctx.as_ref().as_const(),
                in_out.as_mut_ptr(),
                null(),
                0,
                in_out.as_ptr(),
                plaintext_len,
                tag_slice.as_ptr(),
                tag_slice.len(),
                aad.as_ptr(),
                aad.len(),
            )
        }) {
            return Err(Unspecified);
        }

        Ok(())
    }