joplin/packages/lib/services/synchronizer/syncInfoUtils.ts

import Logger from '@joplin/utils/Logger';
import { FileApi } from '../../file-api';
import JoplinDatabase from '../../JoplinDatabase';
import Setting from '../../models/Setting';
import { State } from '../../reducer';
import { PublicPrivateKeyPair } from '../e2ee/ppk';
import { MasterKeyEntity } from '../e2ee/types';
const fastDeepEqual = require('fast-deep-equal');

const logger = Logger.create('syncInfoUtils');

export interface SyncInfoValueBoolean {
	value: boolean;
	updatedTime: number;
}

export interface SyncInfoValueString {
	value: string;
	updatedTime: number;
}

export interface SyncInfoValuePublicPrivateKeyPair {
	value: PublicPrivateKeyPair;
	updatedTime: number;
}

export async function migrateLocalSyncInfo(db: JoplinDatabase) {
	if (Setting.value('syncInfoCache')) return; // Already initialized

	// TODO: if the sync info is changed, there should be steps to migrate from
	// v3 to v4, v4 to v5, etc.

	const masterKeys = await db.selectAll('SELECT * FROM master_keys');

	const masterKeyMap: Record<string, any> = {};
	for (const mk of masterKeys) masterKeyMap[mk.id] = mk;

	const syncInfo = new SyncInfo();
	syncInfo.version = Setting.value('syncVersion');
	syncInfo.e2ee = Setting.valueNoThrow('encryption.enabled', false);
	syncInfo.activeMasterKeyId = Setting.valueNoThrow('encryption.activeMasterKeyId', '');
	syncInfo.masterKeys = masterKeys;

	// We set the timestamp to 0 because we don't know when the source setting
	// has been set. That way, if the parameter is changed later on in any
	// client, the new value will have higher priority. This is to handle this
	// case:
	//
	// - Client 1 upgrade local sync target info (with E2EE = false)
	// - Client 1 set E2EE to true
	// - Client 2 upgrade local sync target info (with E2EE = false)
	// - => If we don't set the timestamp to 0, the local value of client 2 will
	//   have a higher timestamp and E2EE will get disabled, even though this is
	//   most likely not what the user wants.
	syncInfo.setKeyTimestamp('e2ee', 0);
	syncInfo.setKeyTimestamp('activeMasterKeyId', 0);

	await saveLocalSyncInfo(syncInfo);
}

export async function uploadSyncInfo(api: FileApi, syncInfo: SyncInfo) {
	await api.put('info.json', syncInfo.serialize());
}

export async function fetchSyncInfo(api: FileApi): Promise<SyncInfo> {
	const syncTargetInfoText = await api.get('info.json');

	// Returns version 0 if the sync target is empty
	let output: any = { version: 0 };

	if (syncTargetInfoText) {
		output = JSON.parse(syncTargetInfoText);
		if (!output.version) throw new Error('Missing "version" field in info.json');
	} else {
		// If info.json is not present, this might be an old sync target, in
		// which case we can at least get the version number from version.txt
		const oldVersion = await api.get('.sync/version.txt');
		if (oldVersion) output = { version: 1 };
	}

	return fixSyncInfo(new SyncInfo(JSON.stringify(output)));
}

export function saveLocalSyncInfo(syncInfo: SyncInfo) {
	Setting.setValue('syncInfoCache', syncInfo.serialize());
}

const fixSyncInfo = (syncInfo: SyncInfo) => {
	if (syncInfo.activeMasterKeyId) {
		if (!syncInfo.masterKeys || !syncInfo.masterKeys.find(mk => mk.id === syncInfo.activeMasterKeyId)) {
			logger.warn(`Sync info is using a non-existent key as the active key - clearing it: ${syncInfo.activeMasterKeyId}`);
			syncInfo.activeMasterKeyId = '';
		}
	}
	return syncInfo;
};

export function localSyncInfo(): SyncInfo {
	return fixSyncInfo(new SyncInfo(Setting.value('syncInfoCache')));
}

export function localSyncInfoFromState(state: State): SyncInfo {
	return new SyncInfo(state.settings['syncInfoCache']);
}

// When deciding which master key should be active we should take into account
// whether it's been used or not. If it's been used before it should most likely
// remain the active one, regardless of timestamps. This is because the extra
// key was most likely created by mistake by the user, in particular in this
// kind of scenario:
//
// - Client 1 setup sync with sync target
// - Client 1 enable encryption
// - Client 1 sync
//
// Then user 2 does the same:
//
// - Client 2 setup sync with sync target
// - Client 2 enable encryption
// - Client 2 sync
//
// The problem is that enabling encryption was not needed since it was already
// done (and recorded in info.json) on the sync target. As a result an extra key
// has been created and it has been set as the active one, but we shouldn't use
// it. Instead the key created by client 1 should be used and made active again.
//
// And we can do this using the "hasBeenUsed" field which tells us which keys
// has already been used to encrypt data. In this case, at the moment we compare
// local and remote sync info (before synchronising the data), key1.hasBeenUsed
// is true, but key2.hasBeenUsed is false.
//
// 2023-05-30: Additionally, if one key is enabled and the other is not, we
// always pick the enabled one regardless of usage.
const mergeActiveMasterKeys = (s1: SyncInfo, s2: SyncInfo, output: SyncInfo) => {
	const activeMasterKey1 = getActiveMasterKey(s1);
	const activeMasterKey2 = getActiveMasterKey(s2);
	let doDefaultAction = false;

	if (activeMasterKey1 && activeMasterKey2) {
		if (masterKeyEnabled(activeMasterKey1) && !masterKeyEnabled(activeMasterKey2)) {
			output.setWithTimestamp(s1, 'activeMasterKeyId');
		} else if (!masterKeyEnabled(activeMasterKey1) && masterKeyEnabled(activeMasterKey2)) {
			output.setWithTimestamp(s2, 'activeMasterKeyId');
		} else if (activeMasterKey1.hasBeenUsed && !activeMasterKey2.hasBeenUsed) {
			output.setWithTimestamp(s1, 'activeMasterKeyId');
		} else if (!activeMasterKey1.hasBeenUsed && activeMasterKey2.hasBeenUsed) {
			output.setWithTimestamp(s2, 'activeMasterKeyId');
		} else {
			doDefaultAction = true;
		}
	} else {
		doDefaultAction = true;
	}

	if (doDefaultAction) {
		output.setWithTimestamp(s1.keyTimestamp('activeMasterKeyId') > s2.keyTimestamp('activeMasterKeyId') ? s1 : s2, 'activeMasterKeyId');
	}
};

export function mergeSyncInfos(s1: SyncInfo, s2: SyncInfo): SyncInfo {
	const output: SyncInfo = new SyncInfo();

	output.setWithTimestamp(s1.keyTimestamp('e2ee') > s2.keyTimestamp('e2ee') ? s1 : s2, 'e2ee');
	output.setWithTimestamp(s1.keyTimestamp('ppk') > s2.keyTimestamp('ppk') ? s1 : s2, 'ppk');
	output.version = s1.version > s2.version ? s1.version : s2.version;

	mergeActiveMasterKeys(s1, s2, output);

	output.masterKeys = s1.masterKeys.slice();

	for (const mk of s2.masterKeys) {
		const idx = output.masterKeys.findIndex(m => m.id === mk.id);
		if (idx < 0) {
			output.masterKeys.push(mk);
		} else {
			const mk2 = output.masterKeys[idx];
			output.masterKeys[idx] = mk.updated_time > mk2.updated_time ? mk : mk2;
		}
	}

	return output;
}

export function syncInfoEquals(s1: SyncInfo, s2: SyncInfo): boolean {
	return fastDeepEqual(s1.toObject(), s2.toObject());
}

export class SyncInfo {

	private version_ = 0;
	private e2ee_: SyncInfoValueBoolean;
	private activeMasterKeyId_: SyncInfoValueString;
	private masterKeys_: MasterKeyEntity[] = [];
	private ppk_: SyncInfoValuePublicPrivateKeyPair;

	public constructor(serialized: string = null) {
		this.e2ee_ = { value: false, updatedTime: 0 };
		this.activeMasterKeyId_ = { value: '', updatedTime: 0 };
		this.ppk_ = { value: null, updatedTime: 0 };

		if (serialized) this.load(serialized);
	}

	public toObject(): any {
		return {
			version: this.version,
			e2ee: this.e2ee_,
			activeMasterKeyId: this.activeMasterKeyId_,
			masterKeys: this.masterKeys,
			ppk: this.ppk_,
		};
	}

	public serialize(): string {
		return JSON.stringify(this.toObject(), null, '\t');
	}

	public load(serialized: string) {
		const s: any = JSON.parse(serialized);
		this.version = 'version' in s ? s.version : 0;
		this.e2ee_ = 'e2ee' in s ? s.e2ee : { value: false, updatedTime: 0 };
		this.activeMasterKeyId_ = 'activeMasterKeyId' in s ? s.activeMasterKeyId : { value: '', updatedTime: 0 };
		this.masterKeys_ = 'masterKeys' in s ? s.masterKeys : [];
		this.ppk_ = 'ppk' in s ? s.ppk : { value: null, updatedTime: 0 };

		// Migration for master keys that didn't have "hasBeenUsed" property -
		// in that case we assume they've been used at least once.
		for (const mk of this.masterKeys_) {
			if (!('hasBeenUsed' in mk) || mk.hasBeenUsed === undefined) {
				mk.hasBeenUsed = true;
			}
		}
	}

	public setWithTimestamp(fromSyncInfo: SyncInfo, propName: string) {
		if (!(propName in (this as any))) throw new Error(`Invalid prop name: ${propName}`);

		(this as any)[propName] = (fromSyncInfo as any)[propName];
		this.setKeyTimestamp(propName, fromSyncInfo.keyTimestamp(propName));
	}

	public get version(): number {
		return this.version_;
	}

	public set version(v: number) {
		if (v === this.version_) return;

		this.version_ = v;
	}

	public get ppk() {
		return this.ppk_.value;
	}

	public set ppk(v: PublicPrivateKeyPair) {
		if (v === this.ppk_.value) return;

		this.ppk_ = { value: v, updatedTime: Date.now() };
	}

	public get e2ee(): boolean {
		return this.e2ee_.value;
	}

	public set e2ee(v: boolean) {
		if (v === this.e2ee) return;

		this.e2ee_ = { value: v, updatedTime: Date.now() };
	}

	public get activeMasterKeyId(): string {
		return this.activeMasterKeyId_.value;
	}

	public set activeMasterKeyId(v: string) {
		if (v === this.activeMasterKeyId) return;

		this.activeMasterKeyId_ = { value: v, updatedTime: Date.now() };
	}

	public get masterKeys(): MasterKeyEntity[] {
		return this.masterKeys_;
	}

	public set masterKeys(v: MasterKeyEntity[]) {
		if (JSON.stringify(v) === JSON.stringify(this.masterKeys_)) return;

		this.masterKeys_ = v;
	}

	public keyTimestamp(name: string): number {
		if (!(`${name}_` in (this as any))) throw new Error(`Invalid name: ${name}`);
		return (this as any)[`${name}_`].updatedTime;
	}

	public setKeyTimestamp(name: string, timestamp: number) {
		if (!(`${name}_` in (this as any))) throw new Error(`Invalid name: ${name}`);
		(this as any)[`${name}_`].updatedTime = timestamp;
	}

}

// ---------------------------------------------------------
// Shortcuts to simplify the refactoring
// ---------------------------------------------------------

export function getEncryptionEnabled() {
	return localSyncInfo().e2ee;
}

export function setEncryptionEnabled(v: boolean, activeMasterKeyId = '') {
	const s = localSyncInfo();
	s.e2ee = v;
	if (activeMasterKeyId) s.activeMasterKeyId = activeMasterKeyId;
	saveLocalSyncInfo(s);
}

export function getActiveMasterKeyId() {
	return localSyncInfo().activeMasterKeyId;
}

export function setActiveMasterKeyId(id: string) {
	const s = localSyncInfo();
	s.activeMasterKeyId = id;
	saveLocalSyncInfo(s);
}

export function getActiveMasterKey(s: SyncInfo = null): MasterKeyEntity | null {
	s = s || localSyncInfo();
	if (!s.activeMasterKeyId) return null;
	return s.masterKeys.find(mk => mk.id === s.activeMasterKeyId);
}

export function setMasterKeyEnabled(mkId: string, enabled = true) {
	const s = localSyncInfo();
	const idx = s.masterKeys.findIndex(mk => mk.id === mkId);
	if (idx < 0) throw new Error(`No such master key: ${mkId}`);

	// Disabled for now as it's needed to disable even the main master key when the password has been forgotten
	// https://discourse.joplinapp.org/t/syncing-error-with-joplin-cloud-and-e2ee-master-key-is-not-loaded/20115/5?u=laurent
	//
	// if (mkId === getActiveMasterKeyId() && !enabled) throw new Error('The active master key cannot be disabled');

	s.masterKeys[idx] = {
		...s.masterKeys[idx],
		enabled: enabled ? 1 : 0,
		updated_time: Date.now(),
	};

	saveLocalSyncInfo(s);
}

export const setMasterKeyHasBeenUsed = (s: SyncInfo, mkId: string) => {
	const idx = s.masterKeys.findIndex(mk => mk.id === mkId);
	if (idx < 0) throw new Error(`No such master key: ${mkId}`);

	s.masterKeys[idx] = {
		...s.masterKeys[idx],
		hasBeenUsed: true,
		updated_time: Date.now(),
	};

	saveLocalSyncInfo(s);

	return s;
};

export function masterKeyEnabled(mk: MasterKeyEntity): boolean {
	if ('enabled' in mk) return !!mk.enabled;
	return true;
}

export function addMasterKey(syncInfo: SyncInfo, masterKey: MasterKeyEntity) {
	// Sanity check - because shouldn't happen
	if (syncInfo.masterKeys.find(mk => mk.id === masterKey.id)) throw new Error('Master key is already present');

	syncInfo.masterKeys.push(masterKey);
	saveLocalSyncInfo(syncInfo);
}

export function setPpk(ppk: PublicPrivateKeyPair) {
	const syncInfo = localSyncInfo();
	syncInfo.ppk = ppk;
	saveLocalSyncInfo(syncInfo);
}

export function masterKeyById(id: string) {
	return localSyncInfo().masterKeys.find(mk => mk.id === id);
}