Add exit node selection to the clients

server/lib/exitNodes/calculateExitNodeWeight.ts

@@ -0,0 +1,40 @@
+import { db, sites, clients } from "@server/db";
+import { and, eq, count } from "drizzle-orm";
+
+// (MAX_CONNECTIONS - current_connections) / MAX_CONNECTIONS)
+// higher = more desirable
+// like saying, this node has x% of its capacity left
+export async function calculateExitNodeWeight(
+    exitNodeId: number,
+    maxConnections: number | null | undefined
+): Promise<number | null> {
+    if (maxConnections === null || maxConnections === undefined) {
+        return 1;
+    }
+
+    const [[siteConnections], [clientConnections]] = await Promise.all([
+        db
+            .select({ count: count() })
+            .from(sites)
+            .where(
+                and(eq(sites.exitNodeId, exitNodeId), eq(sites.online, true))
+            ),
+        db
+            .select({ count: count() })
+            .from(clients)
+            .where(
+                and(
+                    eq(clients.exitNodeId, exitNodeId),
+                    eq(clients.online, true)
+                )
+            )
+    ]);
+
+    const currentConnections = siteConnections.count + clientConnections.count;
+
+    if (currentConnections >= maxConnections) {
+        return null;
+    }
+
+    return (maxConnections - currentConnections) / maxConnections;
+}

server/lib/exitNodes/exitNodes.ts

@@ -1,6 +1,5 @@
 import { db, exitNodes, Transaction } from "@server/db";
 import logger from "@server/logger";
-import { ExitNodePingResult } from "@server/routers/newt";
 import { eq } from "drizzle-orm";
 
 export async function verifyExitNodeOrgAccess(
@@ -52,6 +51,16 @@ export async function listExitNodes(
     return allExitNodes;
 }
 
+export type ExitNodePingResult = {
+    exitNodeId: number;
+    latencyMs: number;
+    weight: number;
+    error?: string;
+    exitNodeName: string;
+    endpoint: string;
+    wasPreviouslyConnected: boolean;
+};
+
 export function selectBestExitNode(
     pingResults: ExitNodePingResult[]
 ): ExitNodePingResult | null {

server/lib/exitNodes/index.ts

@@ -2,3 +2,4 @@ export * from "./exitNodes";
 export * from "./exitNodeComms";
 export * from "./subnet";
 export * from "./getCurrentExitNodeId";
+export * from "./calculateExitNodeWeight";