// Copyright 2022 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.fido.report;

using zx;

/// The maximum message payload is based on the packet size of 64 bytes for full speed devices.
/// See the CTAP specification for the calculation of this value.
const MAX_DATA_LENGTH uint64 = 7609;

/// CTAPHID commands as defined in the CTAP specification.
/// Note that the logical rather than numeric ordering here matches that in the specification.
type CtapHidCommand = flexible enum {
    /// Mandatory commands required by a CTAPHID device.
    MSG = 0x03;
    CBOR = 0x10;
    INIT = 0x06;
    PING = 0x01;
    CANCEL = 0x11;
    ERROR = 0x3f;
    KEEPALIVE = 0x3b;
    /// Optional commands required by a CTAPHID device. Some devices may not support these.
    WINK = 0x08;
    LOCK = 0x04;

    /// Vendor specific commands may appear in the following range.
    VENDOR_FIRST = 0x40;
    VENDOR_LAST = 0x7F;
};

/// Fields in Response and Request are based on the packet tables in the CTAP specification.
type Request = table {
    1: channel_id uint32;
    2: command_id CtapHidCommand;
    3: payload_len uint16;
    4: data vector<uint8>:MAX_DATA_LENGTH;
};

type Response = table {
    1: channel_id uint32;
    2: data vector<uint8>:MAX_DATA_LENGTH;
};

/// All defined values and fields for this protocol come from the CTAP specification at
/// https://fidoalliance.org/specs/fido-v2.1-ps-20210615/fido-client-to-authenticator-protocol-v2.1-ps-20210615.html#usb-message-and-packet-structure
protocol SecurityKeyDevice {
    /// Send a message (request) to a FIDO key.
    SendMessage(struct {
        request Request;
    }) -> (struct {}) error zx.status;

    /// Wait for and receive a message (response) from a FIDO key.
    /// Returns ZX_ERR_ACCESS_DENIED if `channel_id` does not match the
    /// channel_id in `response`.
    GetMessage(struct {
        channel_id uint32;
    }) -> (struct {
        response Response;
    }) error zx.status;
};