Improvements to connection publishing for sync.

app/src/main/java/com/futo/platformplayer/Utility.kt

@@ -339,6 +339,33 @@ fun ByteArray.fromGzip(): ByteArray {
     return outputStream.toByteArray()
 }
 
+fun findCandidateAddresses(): List<InetAddress> {
+    val candidates = NetworkInterface.getNetworkInterfaces()
+        .toList()
+        .asSequence()
+        .filter(::isUsableInterface)
+        .flatMap { nif ->
+            nif.interfaceAddresses
+                .asSequence()
+                .mapNotNull { ia ->
+                    ia.address.takeIf(::isUsableAddress)?.let { addr ->
+                        nif to ia
+                    }
+                }
+        }
+        .toList()
+
+    return candidates
+        .sortedWith(
+            compareBy<Pair<NetworkInterface, InterfaceAddress>>(
+                { addressScore(it.second.address) },
+                { interfaceScore(it.first) },
+                { -it.second.networkPrefixLength.toInt() },
+                { -it.first.mtu }
+            )
+        ).map { it.second.address }
+}
+
 fun findPreferredAddress(): InetAddress? {
     val candidates = NetworkInterface.getNetworkInterfaces()
         .toList()

app/src/main/java/com/futo/platformplayer/sync/internal/SyncService.kt

@@ -328,7 +328,7 @@ class SyncService(
                     val now = System.currentTimeMillis()
                     synchronized(_mdnsCache) {
                         for ((pkey, info) in _mdnsCache) {
-                            if (!database.isAuthorized(pkey) || isConnected(pkey)) continue
+                            if (!database.isAuthorized(pkey) || getLinkType(pkey) == LinkType.Direct) continue
 
                             val last = synchronized(_lastConnectTimesMdns) {
                                 _lastConnectTimesMdns[pkey] ?: 0L
@@ -360,8 +360,8 @@ class SyncService(
             while (_started) {
                 val authorizedDevices = database.getAllAuthorizedDevices() ?: arrayOf()
                 val addressesToConnect = authorizedDevices.mapNotNull {
-                    val connected = isConnected(it)
+                    val connectedDirectly = getLinkType(it) == LinkType.Direct
-                    if (connected) {
+                    if (connectedDirectly) {
                         return@mapNotNull null
                     }
 
@@ -468,8 +468,13 @@ class SyncService(
                                         while (_started && !socketClosed) {
                                             val unconnectedAuthorizedDevices =
                                                 database.getAllAuthorizedDevices()
-                                                    ?.filter { !isConnected(it) }?.toTypedArray()
+                                                    ?.filter {
-                                                    ?: arrayOf()
+                                                        if (Settings.instance.synchronization.connectLocalDirectThroughRelay) {
+                                                            getLinkType(it) != LinkType.Direct
+                                                        } else {
+                                                            !isConnected(it)
+                                                        }
+                                                    }?.toTypedArray() ?: arrayOf()
                                             relaySession.publishConnectionInformation(
                                                 unconnectedAuthorizedDevices,
                                                 settings.listenerPort,
@@ -497,7 +502,7 @@ class SyncService(
                                                 val potentialLocalAddresses =
                                                     connectionInfo.ipv4Addresses
                                                         .filter { it != connectionInfo.remoteIp }
-                                                if (connectionInfo.allowLocalDirect && Settings.instance.synchronization.connectLocalDirectThroughRelay) {
+                                                if (getLinkType(targetKey) != LinkType.Direct && connectionInfo.allowLocalDirect && Settings.instance.synchronization.connectLocalDirectThroughRelay) {
                                                     Thread {
                                                         try {
                                                             Log.v(
@@ -529,7 +534,7 @@ class SyncService(
                                                     // TODO: Implement hole punching if needed
                                                 }
 
-                                                if (connectionInfo.allowRemoteRelayed && Settings.instance.synchronization.connectThroughRelay) {
+                                                if (getLinkType(targetKey) == LinkType.None && connectionInfo.allowRemoteRelayed && Settings.instance.synchronization.connectThroughRelay) {
                                                     try {
                                                         Logger.v(
                                                             TAG,
@@ -741,6 +746,7 @@ class SyncService(
         )
     }
 
+    fun getLinkType(publicKey: String): LinkType = synchronized(_sessions) { _sessions[publicKey]?.linkType ?: LinkType.None }
     fun isConnected(publicKey: String): Boolean = synchronized(_sessions) { _sessions[publicKey]?.connected ?: false }
     fun isAuthorized(publicKey: String): Boolean = database.isAuthorized(publicKey)
     fun getSession(publicKey: String): SyncSession? = synchronized(_sessions) { _sessions[publicKey] }

app/src/main/java/com/futo/platformplayer/sync/internal/SyncSocketSession.kt

@@ -2,6 +2,7 @@ package com.futo.platformplayer.sync.internal
 
 import android.os.Build
 import com.futo.platformplayer.ensureNotMainThread
+import com.futo.platformplayer.findCandidateAddresses
 import com.futo.platformplayer.logging.Logger
 import com.futo.platformplayer.noise.protocol.CipherStatePair
 import com.futo.platformplayer.noise.protocol.DHState
@@ -1078,20 +1079,9 @@ class SyncSocketSession {
     ) {
         if (authorizedKeys.size > 255) throw IllegalArgumentException("Number of authorized keys exceeds 255")
 
-        val ipv4Addresses = mutableListOf<String>()
+        val candidateAddresses = findCandidateAddresses()
-        val ipv6Addresses = mutableListOf<String>()
+        val ipv4Addresses = candidateAddresses.filterIsInstance<Inet4Address>()
-        for (nic in NetworkInterface.getNetworkInterfaces()) {
+        val ipv6Addresses = candidateAddresses.filterIsInstance<Inet6Address>()
-            if (nic.isUp) {
-                for (addr in nic.inetAddresses) {
-                    if (!addr.isLoopbackAddress) {
-                        when (addr) {
-                            is Inet4Address -> ipv4Addresses.add(addr.hostAddress)
-                            is Inet6Address -> ipv6Addresses.add(addr.hostAddress)
-                        }
-                    }
-                }
-            }
-        }
 
         val deviceName = getDeviceName()
         val nameBytes = getLimitedUtf8Bytes(deviceName, 255)
@@ -1103,12 +1093,12 @@ class SyncSocketSession {
         data.put(nameBytes)
         data.put(ipv4Addresses.size.toByte())
         for (addr in ipv4Addresses) {
-            val addrBytes = InetAddress.getByName(addr).address
+            val addrBytes = addr.address
             data.put(addrBytes)
         }
         data.put(ipv6Addresses.size.toByte())
         for (addr in ipv6Addresses) {
-            val addrBytes = InetAddress.getByName(addr).address
+            val addrBytes = addr.address
             data.put(addrBytes)
         }
         data.put(if (allowLocalDirect) 1 else 0)