openmls 0.8.1

A Rust implementation of the Messaging Layer Security (MLS) protocol, as defined in RFC 9420.
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use crate::{
    credentials::test_utils::new_credential,
    key_packages::KeyPackageBundle,
    treesync::{node::Node, RatchetTree, TreeSync},
};

// Verifies that when we add a leaf to a tree with blank leaf nodes, the leaf will be added at the leftmost free leaf index
#[openmls_test::openmls_test]
fn test_free_leaf_computation() {
    let provider = &Provider::default();
    let (c_0, sk_0) = new_credential(provider, b"leaf0", ciphersuite.signature_algorithm());

    let kpb_0 = KeyPackageBundle::generate(provider, &sk_0, ciphersuite, c_0);

    let (c_3, sk_3) = new_credential(provider, b"leaf3", ciphersuite.signature_algorithm());
    let kpb_3 = KeyPackageBundle::generate(provider, &sk_3, ciphersuite, c_3);

    // Build a rudimentary tree with two populated and two empty leaf nodes.
    let ratchet_tree = RatchetTree::trimmed(vec![
        Some(Node::leaf_node(kpb_0.key_package().leaf_node().clone())), // Leaf 0
        None,
        None, // Leaf 1
        None,
        None, // Leaf 2
        None,
        Some(Node::leaf_node(kpb_3.key_package().leaf_node().clone())), // Leaf 3
    ]);

    // Get the encryption key pair from the leaf.
    let tree = TreeSync::from_ratchet_tree(provider.crypto(), ciphersuite, ratchet_tree)
        .expect("error generating tree");

    // Create and add a new leaf. It should go to leaf index 1

    let (c_2, signer_2) = new_credential(provider, b"leaf2", ciphersuite.signature_algorithm());
    let kpb_2 = KeyPackageBundle::generate(provider, &signer_2, ciphersuite, c_2);

    let mut diff = tree.empty_diff();
    let free_leaf_index = diff.free_leaf_index();
    let added_leaf_index = diff
        .add_leaf(kpb_2.key_package().leaf_node().clone())
        .expect("error adding leaf");
    assert_eq!(free_leaf_index.u32(), 1u32);
    assert_eq!(free_leaf_index, added_leaf_index);

    let free_leaf_index = diff.free_leaf_index();

    assert_eq!(free_leaf_index.u32(), 2u32);
}