Stabilize VPN farm startup path

clients/android/app/build.gradle

@@ -30,8 +30,8 @@ android {
         applicationId "su.cin.rapvpn"
         minSdk 26
         targetSdk 35
-        versionCode 190
-        versionName "0.2.190"
+        versionCode 191
+        versionName "0.2.191"
         buildConfigField "String", "DEFAULT_BACKEND_URL", "\"${normalizeGradleString(defaultBackendUrl)}\""
         buildConfigField "String", "DEFAULT_CLUSTER_ID", "\"${normalizeGradleString(defaultClusterId)}\""
         buildConfigField "String", "DEFAULT_ORGANIZATION_ID", "\"${normalizeGradleString(defaultOrganizationId)}\""

clients/android/app/src/main/java/su/cin/rapvpn/VpnPacketWebSocketRelay.java

@@ -25,6 +25,7 @@ final class VpnPacketWebSocketRelay {
     private static final int MAX_PACKET_BATCH_BYTES = 1024 * 1024;
     private static final int MAX_SINGLE_PACKET_BYTES = 65535;
     private static final long CONNECTING_STALE_MS = 8000;
+    private static final long OPEN_WAIT_MS = 3500;
 
     private final String baseUrl;
     private final VpnService vpnService;
@@ -123,8 +124,12 @@ final class VpnPacketWebSocketRelay {
             return true;
         }
         connect(clusterId, vpnConnectionId);
+        if (!awaitOpen(OPEN_WAIT_MS)) {
+            return false;
+        }
         WebSocket socket = webSocket;
-        if (socket == null || !open) {
+        if (socket == null) {
+            lastError = "websocket missing after open";
             return false;
         }
         byte[] payload = encodePacketBatch(packets);
@@ -140,6 +145,7 @@ final class VpnPacketWebSocketRelay {
 
     List<byte[]> receiveClientPacketBatch(String clusterId, String vpnConnectionId, int timeoutMs) throws InterruptedException {
         connect(clusterId, vpnConnectionId);
+        awaitOpen(Math.min(OPEN_WAIT_MS, Math.max(1, timeoutMs)));
         int waitMs = Math.max(1, timeoutMs);
         List<byte[]> packets = incoming.poll(waitMs, TimeUnit.MILLISECONDS);
         return packets == null ? new ArrayList<>() : packets;
@@ -165,6 +171,29 @@ final class VpnPacketWebSocketRelay {
         webSocket = null;
     }
 
+    private boolean awaitOpen(long timeoutMs) {
+        long deadline = System.currentTimeMillis() + Math.max(1, timeoutMs);
+        synchronized (lock) {
+            while (!open && connecting) {
+                long waitMs = deadline - System.currentTimeMillis();
+                if (waitMs <= 0) {
+                    break;
+                }
+                try {
+                    lock.wait(waitMs);
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    lastError = "interrupted waiting for websocket open";
+                    return false;
+                }
+            }
+            if (!open && "connecting".equals(lastError)) {
+                lastError = "connecting_timeout";
+            }
+            return open;
+        }
+    }
+
     private String webSocketUrl(String clusterId, String vpnConnectionId) {
         try {
             URI uri = URI.create(baseUrl);
@@ -187,10 +216,13 @@ final class VpnPacketWebSocketRelay {
     private final class Listener extends WebSocketListener {
         @Override
         public void onOpen(WebSocket webSocket, Response response) {
-            open = true;
-            connecting = false;
-            reconnectAfterMs = 0;
-            lastError = "";
+            synchronized (lock) {
+                open = true;
+                connecting = false;
+                reconnectAfterMs = 0;
+                lastError = "";
+                lock.notifyAll();
+            }
             Log.i(TAG, "vpn packet websocket opened " + baseUrl);
         }
 
@@ -208,22 +240,28 @@ final class VpnPacketWebSocketRelay {
 
         @Override
         public void onClosed(WebSocket webSocket, int code, String reason) {
-            open = false;
-            connecting = false;
-            reconnectAfterMs = System.currentTimeMillis() + 1000;
-            lastError = "closed " + code + " " + reason;
+            synchronized (lock) {
+                open = false;
+                connecting = false;
+                reconnectAfterMs = System.currentTimeMillis() + 1000;
+                lastError = "closed " + code + " " + reason;
+                lock.notifyAll();
+            }
         }
 
         @Override
         public void onFailure(WebSocket webSocket, Throwable t, Response response) {
-            open = false;
-            connecting = false;
-            reconnectAfterMs = System.currentTimeMillis() + 3000;
             String responseStatus = "";
             if (response != null) {
                 responseStatus = " status=" + response.code();
             }
-            lastError = (t == null ? "websocket failure" : t.getClass().getSimpleName() + ": " + t.getMessage()) + responseStatus;
+            synchronized (lock) {
+                open = false;
+                connecting = false;
+                reconnectAfterMs = System.currentTimeMillis() + 3000;
+                lastError = (t == null ? "websocket failure" : t.getClass().getSimpleName() + ": " + t.getMessage()) + responseStatus;
+                lock.notifyAll();
+            }
             Log.w(TAG, "vpn packet websocket failed " + baseUrl + ": " + lastError);
         }
     }