PairedDeviceStore.kt

1package com.peachpasswords.sync23import android.content.Context4import androidx.security.crypto.EncryptedSharedPreferences5import androidx.security.crypto.MasterKey6import dagger.hilt.android.qualifiers.ApplicationContext7import kotlinx.coroutines.channels.awaitClose8import kotlinx.coroutines.flow.Flow9import kotlinx.coroutines.flow.callbackFlow10import kotlinx.serialization.builtins.ListSerializer11import kotlinx.serialization.json.Json12import javax.inject.Inject13import javax.inject.Singleton1415/**16 * Persistent registry of paired devices, encrypted at rest with17 * EncryptedSharedPreferences (same construction as DuressConfigStore /18 * LicenseRepository, v2.1.36). The whole list lives under a single key as a19 * kotlinx.serialization JSON array of the REAL [PairedDevice] (sync package).20 *21 * Reconciliation with the C7 brief:22 *  - The brief invents a fresh `PairedDevice(id, name, publicKey: ByteArray,23 *    lastSeen, trustStatus, lastSyncAt)`. That type does NOT exist in this24 *    shape. The real [PairedDevice] (PairedDevice.kt) keys on `deviceId`, holds25 *    the public key as `longTermPublicKeyHex` (hex, not ByteArray), and tracks26 *    `pairedAt` / `lastSyncedAt` / `lastKnownIp`. This store reuses it verbatim;27 *    Base64 publicKey storage is therefore unnecessary — the hex field is the28 *    canonical wire form already produced by PairingFrames.frameToPairedDevice.29 *  - The brief's `TrustStatus` enum does not exist either. The real model uses a30 *    nullable `trustSource: String?` (e.g. "direct", "manifest"). Trust state is31 *    expressed there. See C7-INTEGRATION.md for the trust-status delta.32 *  - `updateLastSync` here maps to the real `lastSyncedAt` field. There is no33 *    `lastSeen` field on the real PairedDevice; [updateLastSeen] folds into34 *    `lastKnownIp` refresh + `lastSyncedAt` is left untouched. It is kept as a35 *    no-op-friendly hook so callers from the brief compile; see integration note.36 */37@Singleton38class PairedDeviceStore @Inject constructor(39    @ApplicationContext context: Context,40) : PairedDeviceRegistry {41    private val masterKey = MasterKey.Builder(context)42        .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)43        .build()4445    private val prefs = EncryptedSharedPreferences.create(46        context,47        PREFS_FILE,48        masterKey,49        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,50        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM,51    )5253    private val listSerializer = ListSerializer(PairedDevice.serializer())54    private val revocationSerializer = ListSerializer(DeviceRevocation.serializer())5556    override fun getAll(): List<PairedDevice> {57        val raw = prefs.getString(KEY_DEVICES, null) ?: return emptyList()58        return runCatching { json.decodeFromString(listSerializer, raw) }.getOrDefault(emptyList())59    }6061    override fun get(id: String): PairedDevice? = getAll().firstOrNull { it.deviceId == id }6263    override fun getByPubkey(pubkeyHex: String): PairedDevice? =64        getAll().firstOrNull {65            it.longTermPublicKeyHex?.let { key -> CryptoCompare.hex(key, pubkeyHex) } == true66        }6768    /** Insert or replace by [PairedDevice.deviceId]. */69    override fun upsert(device: PairedDevice) {70        val next = getAll().filterNot { it.deviceId == device.deviceId } + device71        persist(next)72    }7374    override fun remove(deviceId: String) {75        persist(getAll().filterNot { it.deviceId == deviceId })76    }7778    /**79     * Commit a staged manifest in one synchronous SharedPreferences transaction.80     * `apply()` is appropriate for ordinary UI writes, but it would expose each81     * per-device edit independently to observers and could leave an old-session82     * manifest half-applied across a lock. `commit()` updates both keys together83     * in memory and does not return until the durable write has completed.84     */85    override fun applyManifestBatch(batch: DeviceManifestRegistryBatch): Boolean {86        val priorPrefs = readPrefsState()87        val currentDevices = getAll()88        val currentRevocations = listRevocations()89        val knownRevokedIds = currentRevocations.map { it.deviceId }.toSet()90        val freshRevocations = batch.incomingRevocations.filterNot { knownRevokedIds.contains(it.deviceId) }91        val nextRevocations = (currentRevocations + freshRevocations).takeLast(MAX_REVOCATIONS)92        val removed = batch.removals93        val nextDevices = currentDevices94            .filterNot { removed.contains(it.deviceId) }95            .toMutableList()96        batch.upserts.forEach { device ->97            nextDevices.removeAll { it.deviceId == device.deviceId }98            nextDevices += device99        }100101        val nextPrefs = RegistryPrefsState(102            devices = json.encodeToString(listSerializer, nextDevices),103            revocations = json.encodeToString(revocationSerializer, nextRevocations),104        )105        // Explicitly restore the old encrypted-preference values when commit()106        // reports false. The platform usually keeps them in memory, but a real107        // store failure must not rely on that undocumented outcome.108        return commitWithRollback(priorPrefs, nextPrefs, ::writePrefsState)109    }110111    // ── Device revocation (Part 5 §C) ────────────────────────────────────────112113    override fun listRevocations(): List<DeviceRevocation> {114        val raw = prefs.getString(KEY_REVOCATIONS, null) ?: return emptyList()115        return runCatching { json.decodeFromString(revocationSerializer, raw) }116            .getOrDefault(emptyList())117    }118119    /**120     * Revoke a device: record it, then drop it from the registry. The record121     * rides out in every manifest this device signs from now on. A stale entry122     * may survive in the pending-vouch queue; the confirm path re-checks123     * revocation before promoting anything out of it.124     */125    fun revoke(126        deviceId: String,127        revokedByDeviceId: String,128        nowMs: Long = System.currentTimeMillis(),129    ): DeviceRevocation? {130        val currentDevices = getAll()131        val currentRevocations = listRevocations()132        val mutation = planDeviceRevocation(133            devices = currentDevices,134            revocations = currentRevocations,135            deviceId = deviceId,136            revokedByDeviceId = revokedByDeviceId,137            nowMs = nowMs,138        )139        if (mutation.revocations !== currentRevocations) {140            persistRevocations(mutation.revocations)141        }142        if (mutation.devices != currentDevices) {143            persist(mutation.devices)144        }145        return mutation.added146    }147148    /**149     * `revokedAt` is peer-supplied and is NOT used for ordering — revocation is150     * terminal, so an incoming record can never displace one already held.151     */152    override fun mergeRevocations(incoming: List<DeviceRevocation>): List<String> {153        val existing = listRevocations()154        val known = existing.map { it.deviceId }.toSet()155        val fresh = incoming.filterNot { known.contains(it.deviceId) }156        if (fresh.isEmpty()) return emptyList()157        persistRevocations((existing + fresh).takeLast(MAX_REVOCATIONS))158        return fresh.map { it.deviceId }159    }160161    /**162     * Clear a revocation. The ONLY legitimate caller is a direct, SAS-confirmed163     * re-pair — a physically present user on both devices. Never call this from164     * a path a remote peer can reach.165     */166    override fun clearRevocation(deviceId: String) {167        val existing = listRevocations()168        val filtered = existing.filterNot { it.deviceId == deviceId }169        if (filtered.size != existing.size) persistRevocations(filtered)170    }171172    fun clear() {173        prefs.edit()174            .remove(KEY_DEVICES)175            .remove(KEY_REVOCATIONS)176            .apply()177    }178179    /**180     * Refresh the device's `lastKnownIp` (the closest real analogue to the181     * brief's `lastSeen`). No-op when the id is unknown or [ip] is null.182     */183    fun updateLastSeen(id: String, ip: String? = null) {184        val current = get(id) ?: return185        if (ip == null) return186        upsert(current.copy(lastKnownIp = ip))187    }188189    fun updateLastSync(id: String, at: Long = System.currentTimeMillis()) {190        val current = get(id) ?: return191        upsert(current.copy(lastSyncedAt = at))192    }193194    /**195     * Reconnect prefers each pair's relay over the global fallback, so a relay196     * change in Settings only reaches established pairs by being written into197     * them. Skips the write when nothing moved, so the observers behind the198     * device list do not churn on a refused change.199     */200    fun propagateRelaySetting(mode: SyncMode, storedRelayUrl: String) {201        val current = getAll()202        val next = withRelaySetting(current, mode, storedRelayUrl)203        if (next != current) persist(next)204    }205206    /**207     * Observe the full list. EncryptedSharedPreferences supports208     * OnSharedPreferenceChangeListener, so this emits on every persist —209     * including writes from other components in-process.210     */211    fun observeAll(): Flow<List<PairedDevice>> = callbackFlow {212        trySend(getAll())213        val listener = android.content.SharedPreferences.OnSharedPreferenceChangeListener { _, key ->214            if (key == KEY_DEVICES || key == null) trySend(getAll())215        }216        prefs.registerOnSharedPreferenceChangeListener(listener)217        awaitClose { prefs.unregisterOnSharedPreferenceChangeListener(listener) }218    }219220    private fun persistRevocations(records: List<DeviceRevocation>) {221        prefs.edit()222            .putString(KEY_REVOCATIONS, json.encodeToString(revocationSerializer, records))223            .apply()224    }225226    private fun persist(devices: List<PairedDevice>) {227        prefs.edit()228            .putString(KEY_DEVICES, json.encodeToString(listSerializer, devices))229            .apply()230    }231232    private data class RegistryPrefsState(233        val devices: String?,234        val revocations: String?,235    )236237    private fun readPrefsState(): RegistryPrefsState = RegistryPrefsState(238        devices = prefs.getString(KEY_DEVICES, null),239        revocations = prefs.getString(KEY_REVOCATIONS, null),240    )241242    private fun writePrefsState(state: RegistryPrefsState): Boolean {243        val edit = prefs.edit()244        if (state.devices == null) edit.remove(KEY_DEVICES) else edit.putString(KEY_DEVICES, state.devices)245        if (state.revocations == null) edit.remove(KEY_REVOCATIONS) else edit.putString(KEY_REVOCATIONS, state.revocations)246        return edit.commit()247    }248249    private companion object {250        const val PREFS_FILE = "peach_paired_devices"251        const val KEY_DEVICES = "paired_devices"252        const val KEY_REVOCATIONS = "device_revocations"253        /** Bound the list so a hostile peer cannot grow storage without limit. */254        const val MAX_REVOCATIONS = 500255        val json = Json { encodeDefaults = true; ignoreUnknownKeys = true }256    }257}258259internal data class DeviceRevocationMutation(260    val devices: List<PairedDevice>,261    val revocations: List<DeviceRevocation>,262    val added: DeviceRevocation?,263)264265/**266 * Compute one revoke transaction without Android storage so the impossible267 * "paired and already revoked" state can be regression-tested directly.268 *269 * Older builds could leave that overlap behind. A repeated Remove must still270 * drop the live row even though the terminal record itself is idempotent.271 */272internal fun planDeviceRevocation(273    devices: List<PairedDevice>,274    revocations: List<DeviceRevocation>,275    deviceId: String,276    revokedByDeviceId: String,277    nowMs: Long,278): DeviceRevocationMutation {279    val remaining = devices.filterNot { it.deviceId == deviceId }280    if (revocations.any { it.deviceId == deviceId }) {281        return DeviceRevocationMutation(remaining, revocations, null)282    }283    val device = devices.firstOrNull { it.deviceId == deviceId }284    val record = DeviceRevocation(285        deviceId = deviceId,286        longTermPublicKeyHex = device?.longTermPublicKeyHex ?: "0".repeat(64),287        revokedAt = nowMs,288        revokedByDeviceId = revokedByDeviceId,289    )290    return DeviceRevocationMutation(remaining, revocations + record, record)291}292293/**294 * The mesh relay is pushed out through the same gate that decides whether to295 * dial one: a relay this device refuses to use must not be handed to peers296 * either — pushing Peach's own URL out under a "Private relay" label would tell297 * the same lie one layer down.298 */299internal fun withRelaySetting(300    devices: List<PairedDevice>,301    mode: SyncMode,302    storedRelayUrl: String,303): List<PairedDevice> = when (val decision = relayInForce(mode, storedRelayUrl)) {304    is RelayDecision.Dial -> devices.map { it.copy(relayUrl = decision.relayUrl) }305    is RelayDecision.Refuse -> devices306}