|
| 1 | +/* |
| 2 | + * Copyright 2026 Molly Instant Messenger |
| 3 | + * SPDX-License-Identifier: AGPL-3.0-only |
| 4 | + */ |
| 5 | + |
| 6 | +package org.thoughtcrime.securesms.messages |
| 7 | + |
| 8 | +import android.net.ConnectivityManager |
| 9 | +import android.net.LinkProperties |
| 10 | +import android.net.Network |
| 11 | +import android.net.NetworkCapabilities |
| 12 | +import android.net.NetworkRequest |
| 13 | +import android.os.Build |
| 14 | +import kotlinx.coroutines.CoroutineScope |
| 15 | +import kotlinx.coroutines.Job |
| 16 | +import kotlinx.coroutines.channels.awaitClose |
| 17 | +import kotlinx.coroutines.channels.trySendBlocking |
| 18 | +import kotlinx.coroutines.flow.Flow |
| 19 | +import kotlinx.coroutines.flow.callbackFlow |
| 20 | +import kotlinx.coroutines.flow.conflate |
| 21 | +import kotlinx.coroutines.flow.distinctUntilChanged |
| 22 | +import kotlinx.coroutines.flow.retryWhen |
| 23 | +import kotlinx.coroutines.launch |
| 24 | +import org.signal.core.util.concurrent.SignalDispatchers |
| 25 | +import org.signal.core.util.logging.Log |
| 26 | +import org.signal.core.util.zipWithPrevious |
| 27 | + |
| 28 | +enum class ConnectivityState { |
| 29 | + OFFLINE, |
| 30 | + ONLINE, |
| 31 | + ONLINE_VPN, |
| 32 | + BLOCKED, |
| 33 | + BLOCKED_VPN; |
| 34 | + |
| 35 | + /** Returns true if network traffic expected to reach the Internet. */ |
| 36 | + val hasInternet: Boolean |
| 37 | + get() = this == ONLINE || this == ONLINE_VPN |
| 38 | +} |
| 39 | + |
| 40 | +/** |
| 41 | + * Observes changes in network connectivity and notifies via [onReachabilityChanged]. |
| 42 | + * |
| 43 | + * The current connectivity state is provided immediately upon registration |
| 44 | + * if the device already has network access. |
| 45 | + */ |
| 46 | +class InternetConnectivityMonitor( |
| 47 | + private val connectivityManager: ConnectivityManager, |
| 48 | + private val onReachabilityChanged: (ConnectivityState) -> Unit, |
| 49 | +) { |
| 50 | + companion object { |
| 51 | + private val TAG = Log.tag(InternetConnectivityMonitor::class.java) |
| 52 | + } |
| 53 | + |
| 54 | + private data class NetworkState( |
| 55 | + val validated: Boolean, |
| 56 | + val blocked: Boolean, |
| 57 | + val onVpn: Boolean |
| 58 | + ) { |
| 59 | + val isReachable: Boolean get() = validated && !blocked |
| 60 | + |
| 61 | + companion object { |
| 62 | + val DOWN = NetworkState(validated = false, blocked = false, onVpn = false) |
| 63 | + } |
| 64 | + } |
| 65 | + |
| 66 | + private class NetworkAggregationCallback( |
| 67 | + private val onNetworkStateChanged: (NetworkState) -> Unit, |
| 68 | + private val onVpnLoss: () -> Unit, |
| 69 | + ) : ConnectivityManager.NetworkCallback() { |
| 70 | + |
| 71 | + // Tracks active networks and their states |
| 72 | + private val networks = mutableMapOf<Network, NetworkState>() |
| 73 | + |
| 74 | + override fun onCapabilitiesChanged(network: Network, capabilities: NetworkCapabilities) { |
| 75 | + val validated = capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED) |
| 76 | + val vpn = capabilities.hasTransport(NetworkCapabilities.TRANSPORT_VPN) |
| 77 | + Log.d(TAG, "onCapabilitiesChanged($network, validated=$validated, vpn=$vpn)") |
| 78 | + val existing = networks[network] |
| 79 | + if (existing == null) { |
| 80 | + networks[network] = NetworkState(validated = validated, blocked = false, onVpn = vpn) |
| 81 | + // API 26+ guarantees that onLinkPropertiesChanged is always called next for new networks, |
| 82 | + // followed by onBlockedStatusChanged (on API 29+). |
| 83 | + } else { |
| 84 | + networks[network] = existing.copy(validated = validated, onVpn = vpn) |
| 85 | + onNetworkStateChanged(networks.bestNetworkState()) |
| 86 | + } |
| 87 | + } |
| 88 | + |
| 89 | + override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) { |
| 90 | + if (Build.VERSION.SDK_INT < 29) { |
| 91 | + onNetworkStateChanged(networks.bestNetworkState()) |
| 92 | + } |
| 93 | + } |
| 94 | + |
| 95 | + override fun onBlockedStatusChanged(network: Network, blocked: Boolean) { |
| 96 | + Log.d(TAG, "onBlockedStatusChanged($network, blocked=$blocked)") |
| 97 | + val existing = networks[network] ?: return |
| 98 | + networks[network] = existing.copy(blocked = blocked) |
| 99 | + onNetworkStateChanged(networks.bestNetworkState()) |
| 100 | + } |
| 101 | + |
| 102 | + override fun onLost(network: Network) { |
| 103 | + Log.d(TAG, "onLost($network)") |
| 104 | + val removed = networks.remove(network) |
| 105 | + if (removed?.onVpn == true) { |
| 106 | + onVpnLoss() |
| 107 | + } else { |
| 108 | + onNetworkStateChanged(networks.bestNetworkState()) |
| 109 | + } |
| 110 | + } |
| 111 | + |
| 112 | + private fun Map<Network, NetworkState>.bestNetworkState(): NetworkState { |
| 113 | + return if (isEmpty()) { |
| 114 | + NetworkState.DOWN |
| 115 | + } else { |
| 116 | + // A VPN network is only considered validated if there's also an underlying |
| 117 | + // non-VPN network. |
| 118 | + val hasUnderlyingNet = values.any { !it.onVpn } |
| 119 | + val eligibleStates = values.map { state -> |
| 120 | + state.copy( |
| 121 | + validated = state.validated && hasUnderlyingNet |
| 122 | + ) |
| 123 | + } |
| 124 | + eligibleStates.maxBy { it.rank() } |
| 125 | + } |
| 126 | + } |
| 127 | + |
| 128 | + private fun NetworkState.rank(): Int = |
| 129 | + when { |
| 130 | + isReachable && onVpn -> 3 |
| 131 | + isReachable -> 2 |
| 132 | + blocked -> 1 |
| 133 | + else -> 0 |
| 134 | + } |
| 135 | + } |
| 136 | + |
| 137 | + private fun internetConnectionFlow(): Flow<ConnectivityState> = callbackFlow { |
| 138 | + val callback = NetworkAggregationCallback( |
| 139 | + onNetworkStateChanged = { |
| 140 | + val connectivityState = when { |
| 141 | + it.isReachable && it.onVpn -> ConnectivityState.ONLINE_VPN |
| 142 | + it.isReachable -> ConnectivityState.ONLINE |
| 143 | + it.blocked && it.onVpn -> ConnectivityState.BLOCKED_VPN |
| 144 | + it.blocked -> ConnectivityState.BLOCKED |
| 145 | + else -> ConnectivityState.OFFLINE |
| 146 | + } |
| 147 | + // Should not block as we conflate the flow. |
| 148 | + trySendBlocking(connectivityState) |
| 149 | + }, |
| 150 | + onVpnLoss = { |
| 151 | + // VPN transport disconnected. For always-on VPNs with a kill switch, |
| 152 | + // the underlying network may still appear "UP" but traffic is blocked. |
| 153 | + // Restart the flow to re-evaluate connectivity. |
| 154 | + close(NetworkStateStaleException("VPN loss")) |
| 155 | + } |
| 156 | + ) |
| 157 | + |
| 158 | + val request = NetworkRequest.Builder() |
| 159 | + .removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN) |
| 160 | + .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET) |
| 161 | + .build() |
| 162 | + |
| 163 | + connectivityManager.registerNetworkCallback(request, callback) |
| 164 | + |
| 165 | + awaitClose { |
| 166 | + connectivityManager.unregisterNetworkCallback(callback) |
| 167 | + } |
| 168 | + }.conflate() |
| 169 | + |
| 170 | + private val scope = CoroutineScope(SignalDispatchers.IO) |
| 171 | + private var listenerJob: Job? = null |
| 172 | + |
| 173 | + @Synchronized |
| 174 | + fun register() { |
| 175 | + if (listenerJob != null) return |
| 176 | + |
| 177 | + listenerJob = scope.launch { |
| 178 | + internetConnectionFlow() |
| 179 | + .retryWhen { cause, _ -> |
| 180 | + val retrying = cause is NetworkStateStaleException |
| 181 | + Log.i(TAG, "Re-registering callback ($retrying): ${cause.message}") |
| 182 | + retrying |
| 183 | + } |
| 184 | + .distinctUntilChanged() |
| 185 | + .zipWithPrevious { prevState, state -> |
| 186 | + Log.i(TAG, buildString { |
| 187 | + append("Internet reachability: ") |
| 188 | + prevState?.let { append("$it -> ") } |
| 189 | + append(state) |
| 190 | + }) |
| 191 | + state |
| 192 | + }.collect { |
| 193 | + onReachabilityChanged(it) |
| 194 | + } |
| 195 | + } |
| 196 | + } |
| 197 | + |
| 198 | + @Synchronized |
| 199 | + fun unregister() { |
| 200 | + listenerJob?.cancel() |
| 201 | + listenerJob = null |
| 202 | + } |
| 203 | + |
| 204 | + /** |
| 205 | + * Thrown when the tracked network state is no longer reliable. |
| 206 | + */ |
| 207 | + class NetworkStateStaleException(message: String) : Exception(message) |
| 208 | +} |
0 commit comments