// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.bluetooth.sys;

using fuchsia.bluetooth as bt;

struct SecurityProperties {
    bool authenticated;
    bool secure_connections;
    uint8 encryption_key_size;
};

/// Represents a 128-bit secret key.
struct Key {
    array<uint8>:16 value;
};

/// Represents a key that was received from a peer.
struct PeerKey {
    /// The security properties of this link under which this key was received.
    SecurityProperties security;

    /// The contents of the key.
    Key data;
};

/// Represents a locally generated key that is distributed across one or more bonds.
using LocalKey = Key;

/// Represents a LE Long-Term peer key used for link encyrption. The `ediv` and `rand`
/// fields are zero if distributed using LE Secure Connections pairing.
struct Ltk {
    PeerKey key;
    uint16 ediv;
    uint64 rand;
};

/// The preferred LE connection parameters of the peer.
struct LeConnectionParameters {
    uint16 connection_interval;
    uint16 connection_latency;
    uint16 supervision_timeout;
};

table LeData {
    /// The identity address of the peer.
    [Deprecated = "Use fuchsia.bluetooth.sys/BondingData.address instead"]
    1: bt.Address address;

    /// The peer's preferred connection parameters, if known.
    2: LeConnectionParameters connection_parameters;

    /// Known GATT service UUIDs.
    3: vector<bt.Uuid> services;

    /// The LE long-term key. Present if the link was encrypted. This field is superseded by the
    /// `peer_ltk` and `local_ltk` fields. It is invalid for the `ltk` field to be present
    /// simultaneously with the `peer_ltk` and `local_ltk` fields. In particular:
    ///
    ///   - LeData generated and notified by the Bluetooth system no longer populates this field.
    ///   - LeData supplied by a client of the Bluetooth system (e.g.
    ///     [`fuchsia.bluetooth.sys/Bootstrap`]) can continue to use this field but is encouraged to
    ///     migrate to the new fields.
    [Deprecated]
    4: Ltk ltk;

    /// Identity Resolving RemoteKey used to generate and resolve random addresses.
    5: PeerKey irk;

    /// Connection Signature Resolving RemoteKey used for data signing without encryption.
    6: PeerKey csrk;

    /// LE long-term key used to encrypt a connection when the peer is in the LE
    /// Peripheral role.
    ///
    /// In legacy pairing (`peer_ltk.security.secure_connections` is false),
    /// this key corresponds to the key distributed by the peer. In Secure
    /// Connections pairing there is only one LTK and `peer_ltk` is the same as
    /// `local_ltk`.
    7: Ltk peer_ltk;

    /// LE long-term key used to encrypt a connection when the peer is in the LE
    /// Central role.
    ///
    /// In legacy pairing (`local_ltk.security.secure_connections` is false),
    /// this key corresponds to the key distributed by the local device. In Secure
    /// Connections pairing there is only one LTK and `local_ltk` is the same as
    /// `peer_ltk`.
    8: Ltk local_ltk;
};

table BredrData {
    /// The public device address of the peer.
    [Deprecated = "Use fuchsia.bluetooth.sys/BondingData.address instead"]
    1: bt.Address address;

    /// The peer's preferred piconet role. This is determined by role switch procedures. Paging and
    /// connecting from a peer does not automatically set this flag. If absent, the peer has not
    /// expressed a preference.
    2: bt.ConnectionRole role_preference;

    /// Known service UUIDs obtained from EIR data or SDP.
    3: vector<bt.Uuid> services;

    /// The semi-permanent BR/EDR key. Present if link was paired with Secure
    /// Simple Pairing or stronger.
    4: PeerKey link_key;
};

/// Represents the bonding data for a single peer.
table BondingData {
    /// The identifier that uniquely identifies this peer.
    1: bt.PeerId identifier;

    /// The local Bluetooth identity address that this bond is associated with.
    2: bt.Address local_address;

    /// The name of the peer, if known.
    3: string name;

    /// Bonding data that is present when this peer is paired on the LE transport.
    4: LeData le;

    /// Bonding data that is present when this peer is paired on the BR/EDR transport.
    5: BredrData bredr;

    /// The identity address of the peer.
    6: bt.Address address;
};

/// Represents persistent local host data.
table HostData {
    /// The local Identity Resolving Key used by a bt-host device to generate Resolvable Private
    /// Addresses when privacy is enabled.
    ///
    /// May be absent for hosts that do not use LE privacy, or that only use Non-Resolvable Private
    /// Addresses.
    ///
    /// NOTE: This key is distributed to LE peers during pairing procedures. The client must take
    /// care to assign an IRK that consistent with the local bt-host identity.
    // TODO(fxbug.dev/1408): Document behavior once there is a better privacy policy when `irk` is null.
    1: LocalKey irk;
};

/// Represents the persistent configuration of a single host-subsystem instance. This is used for
/// identity presentation (inquiry, inquiry response, and advertisement) and for bonding secrets
/// recall (encrypting link data to peers associated with this identity).
///
/// Each BR/EDR BD_ADDR and Low Energy public identity address used to bond should have its own
/// Identity instance containing corresponding peers.
///
/// Each Identity instance that supports LE privacy should have an Identity Resolving Key (IRK) that
/// is consistent with that distributed to its bonded peers.
table Identity {
    1: HostData host;

    /// All bonds that use a public identity address must contain the same local address.
    2: vector<BondingData> bonds;
};