Function build_aad

nodedb-wal/src/record/wal_record.rs:192–205

Build the AAD buffer: `preamble_bytes || header_bytes`. When `preamble_bytes` is `None` (no encryption or legacy path), the AAD is just the header bytes. When present, the preamble is prepended.

(
    preamble_bytes: Option<&[u8; PREAMBLE_SIZE]>,
    header_bytes: &[u8; HEADER_SIZE],
)

/// When `preamble_bytes` is `None` (no encryption or legacy path), the AAD
/// is just the header bytes. When present, the preamble is prepended.
pub(crate) fn build_aad(
    preamble_bytes: Option<&[u8; PREAMBLE_SIZE]>,
    header_bytes: &[u8; HEADER_SIZE],
) -> Vec<u8> {
    match preamble_bytes {
        Some(p) => {
            let mut aad = Vec::with_capacity(PREAMBLE_SIZE + HEADER_SIZE);
            aad.extend_from_slice(p);
            aad.extend_from_slice(header_bytes);
            aad
        }
        None => header_bytes.to_vec(),
    }
}

#[cfg(test)]
mod tests {