Make offline checking intervals configurable

Fixes #3855

server/private/lib/offlineThresholds.ts

@@ -0,0 +1,27 @@
+/*
+ * This file is part of a proprietary work.
+ *
+ * Copyright (c) 2025-2026 Fossorial, Inc.
+ * All rights reserved.
+ *
+ * This file is licensed under the Fossorial Commercial License.
+ * You may not use this file except in compliance with the License.
+ * Unauthorized use, copying, modification, or distribution is strictly prohibited.
+ *
+ * This file is not licensed under the AGPLv3.
+ */
+
+import type { OfflineThresholds } from "@server/lib/offlineThresholds";
+import privateConfig from "#private/lib/config";
+
+export function getOfflineThresholds(): OfflineThresholds {
+    const offlineChecker = privateConfig.getRawPrivateConfig().offline_checker;
+
+    return {
+        checkIntervalMs: offlineChecker.check_interval_ms,
+        newtMs: offlineChecker.newt_threshold_ms,
+        newtWireguardMs: offlineChecker.newt_wireguard_threshold_ms,
+        olmMs: offlineChecker.olm_threshold_ms,
+        remoteExitNodeMs: offlineChecker.remote_exit_node_threshold_ms
+    };
+}

server/private/lib/readConfigFile.ts

@@ -18,6 +18,7 @@ import { z } from "zod";
 import { colorsSchema } from "@server/lib/colorsSchema";
 import { build } from "@server/build";
 import { getEnvOrYaml } from "@server/lib/getEnvOrYaml";
+import { DEFAULT_OFFLINE_THRESHOLDS } from "@server/lib/offlineThresholds";
 
 const portSchema = z.number().positive().gt(0).lte(65535);
 
@@ -176,6 +177,36 @@ export const privateConfigSchema = z
                     .default("http://gerbil:3004")
             })
             .prefault({}),
+        // How long a newt site / olm client / remote exit node has to go
+        // without a ping before the offline checker marks it offline, and how
+        // often the checkers run.
+        offline_checker: z
+            .object({
+                check_interval_ms: z
+                    .number()
+                    .int()
+                    .positive()
+                    .default(DEFAULT_OFFLINE_THRESHOLDS.checkIntervalMs),
+                newt_threshold_ms: z
+                    .number()
+                    .int()
+                    .default(DEFAULT_OFFLINE_THRESHOLDS.newtMs),
+                // wireguard sites don't ping, so they are judged by their
+                // last bandwidth update instead
+                newt_wireguard_threshold_ms: z
+                    .number()
+                    .int()
+                    .default(DEFAULT_OFFLINE_THRESHOLDS.newtWireguardMs),
+                olm_threshold_ms: z
+                    .number()
+                    .int()
+                    .default(DEFAULT_OFFLINE_THRESHOLDS.olmMs),
+                remote_exit_node_threshold_ms: z
+                    .number()
+                    .int()
+                    .default(DEFAULT_OFFLINE_THRESHOLDS.remoteExitNodeMs)
+            })
+            .prefault({}),
         flags: z
             .object({
                 enable_redis: z.boolean().optional().default(false),

server/private/routers/remoteExitNode/offlineChecker.ts

@@ -14,11 +14,10 @@
 import { db, exitNodes } from "@server/db";
 import { eq, lt, isNull, and, or } from "drizzle-orm";
 import logger from "@server/logger";
+import { getOfflineThresholds } from "#private/lib/offlineThresholds";
 
 // Track if the offline checker interval is running
 let offlineCheckerInterval: NodeJS.Timeout | null = null;
-const OFFLINE_CHECK_INTERVAL = 30 * 1000; // Check every 30 seconds
-const OFFLINE_THRESHOLD_MS = 2 * 60 * 1000; // 2 minutes
 
 /**
  * Starts the background interval that checks for clients that haven't pinged recently
@@ -31,11 +30,11 @@ export const startRemoteExitNodeOfflineChecker = (): void => {
 
     offlineCheckerInterval = setInterval(async () => {
         try {
-            const twoMinutesAgo = Math.floor(
-                (Date.now() - OFFLINE_THRESHOLD_MS) / 1000
+            const offlineBefore = Math.floor(
+                (Date.now() - getOfflineThresholds().remoteExitNodeMs) / 1000
             );
 
-            // Find clients that haven't pinged in the last 2 minutes and mark them as offline
+            // Find clients that haven't pinged within the offline threshold and mark them as offline
             const offlineNodes = await db
                 .update(exitNodes)
                 .set({ online: false })
@@ -44,7 +43,7 @@ export const startRemoteExitNodeOfflineChecker = (): void => {
                         eq(exitNodes.online, true),
                         eq(exitNodes.type, "remoteExitNode"),
                         or(
-                            lt(exitNodes.lastPing, twoMinutesAgo),
+                            lt(exitNodes.lastPing, offlineBefore),
                             isNull(exitNodes.lastPing)
                         )
                     )
@@ -65,7 +64,7 @@ export const startRemoteExitNodeOfflineChecker = (): void => {
         } catch (error) {
             logger.error("Error in offline checker interval", { error });
         }
-    }, OFFLINE_CHECK_INTERVAL);
+    }, getOfflineThresholds().checkIntervalMs);
 
     logger.debug("Started offline checker interval");
 };