// Copyright 2021 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.ssh;

using zx;

/// Maximum length of a single SSH key. See sshd(8).
const MAX_SSH_KEY_LENGTH uint32 = 8192;

type SshAuthorizedKeyEntry = struct {
    /// The entry in authorized_keys.
    key string:MAX_SSH_KEY_LENGTH;
};

/// Protocol for managing SSH keys on a device.
@discoverable
protocol AuthorizedKeys {
    /// Add a key to the device's authorized key list.
    AddKey(struct {
        key SshAuthorizedKeyEntry;
    }) -> (struct {}) error zx.status;

    /// Watch for keys by sending events to the given KeyWatcher.
    WatchKeys(resource struct {
        watcher server_end:KeyWatcher;
    });

    /// Remove the given key. |key| should be a value returned by |KeyIterator|.
    RemoveKey(struct {
        key SshAuthorizedKeyEntry;
    }) -> (struct {}) error zx.status;
};

type KeyEventType = strict enum {
    /// This key already existed when WatchKeys was called.
    EXISTING = 1;
    /// This key was added after WatchKeys was called.
    ADDED = 2;
    /// This key was removed after WatchKeys was called.
    REMOVED = 3;
    /// This is the end of the EXISTING keys.
    FINISHED_EXISTING = 4;
};

/// Event for an SSH key being added or removed.
type KeyEvent = struct {
    /// What is happening to this key?
    event KeyEventType;
    /// The key. Present for all KeyEventType except FINISHED_EXISTING.
    key box<SshAuthorizedKeyEntry>;
};

/// Used to send updates about the authorized key list from server to client.
protocol KeyWatcher {
    /// Blocks until the next event is ready.
    Next() -> (struct {
        event KeyEvent;
    });
};