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),