From 5345613408f78eab433d7bd6a2b4977da2bd2fc4 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Tue, 21 Mar 2023 00:20:27 -0500
Subject: [PATCH] Add rate-limit policy

---
 rate-limit-policy.ts | 59 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100755 rate-limit-policy.ts

diff --git a/rate-limit-policy.ts b/rate-limit-policy.ts
new file mode 100755
index 0000000..54da6ec
--- /dev/null
+++ b/rate-limit-policy.ts
@@ -0,0 +1,59 @@
+#!/bin/sh
+//bin/true; exec deno run -A "$0" "$@"
+import { readLines } from 'https://deno.land/std@0.178.0/io/mod.ts';
+import { Keydb } from 'https://deno.land/x/keydb@1.0.0/sqlite.ts';
+
+const IP_WHITELIST = (Deno.env.get('IP_WHITELIST') || '').split(',');
+
+const RATE_LIMIT_INTERVAL = Number(Deno.env.get('RATE_LIMIT_INTERVAL') || 60000);
+const RATE_LIMIT_MAX = Number(Deno.env.get('RATE_LIMIT_MAX') || 10);
+
+interface InputMessage {
+  type: 'new' | 'lookback';
+  event: Event;
+  receivedAt: number;
+  sourceType: 'IP4' | 'IP6' | 'Import' | 'Stream' | 'Sync';
+  sourceInfo: string;
+}
+
+interface OutputMessage {
+  id: string;
+  action: 'accept' | 'reject' | 'shadowReject';
+  msg: string;
+}
+
+interface Event {
+  id: string;
+  sig: string;
+  kind: number;
+  tags: string[][];
+  pubkey: string;
+  content: string;
+  created_at: number;
+}
+
+async function handleMessage(msg: InputMessage): Promise<OutputMessage> {
+  if ((msg.sourceType === 'IP4' || msg.sourceType === 'IP6') && !IP_WHITELIST.includes(msg.sourceInfo)) {
+    const db = new Keydb('sqlite:///tmp/strfry-rate-limit-policy.sqlite3');
+    const count = await db.get<number>(msg.sourceInfo) || 0;
+    await db.set(msg.sourceInfo, count + 1, RATE_LIMIT_INTERVAL);
+  
+    if (count >= RATE_LIMIT_MAX) {
+      return {
+        id: msg.event.id,
+        action: 'reject',
+        msg: 'Rate-limited.',
+      };
+    }
+  }
+
+  return {
+    id: msg.event.id,
+    action: 'accept',
+    msg: '',
+  };
+}
+
+for await (const line of readLines(Deno.stdin)) {
+  console.log(JSON.stringify(await handleMessage(JSON.parse(line))));
+}