feat(ext): firewall extension (#184)

* feat: add firewall extention

closes #152

* test: add tetsing for firewall extention

* refactor: removed customLists, use customRanges instead

chore: `deno task check`

* test: removed debug option and added proxy to cloudflare in firewall tests

* feat: check for updates on request

* chore: removed unused file

fix: double checking

---------

Co-authored-by: Samuel Kopp <62482066+boywithkeyboard@users.noreply.github.com>

ext/firewall.ts

@@ -0,0 +1,53 @@
+import { createExtension } from '../mod.ts'
+
+let VPN_LIST: string[] = []
+let DATACENTER_LIST: string[] = []
+let LAST_UPDATE = 0
+
+type FirewallOptions = {
+  blockVPN?: boolean
+  blockDatacenter?: boolean
+  customRanges?: string[]
+}
+
+export const firewall = createExtension<FirewallOptions>({
+  async onRequest({ _: opts, app }) {
+    await checkUpdate()
+    if (
+      opts?.blockVPN && VPN_LIST.find((range) => isIpInRange(app.ip, range))
+    ) {
+      return new Response(null, { status: 403 })
+    }
+    if (
+      opts?.blockDatacenter &&
+      DATACENTER_LIST.find((range) => isIpInRange(app.ip, range))
+    ) return new Response(null, { status: 403 })
+    if (
+      opts?.customRanges &&
+      opts.customRanges.find((range) => isIpInRange(app.ip, range))
+    ) return new Response(null, { status: 403 })
+  },
+})
+
+async function checkUpdate() {
+  if (Date.now() - LAST_UPDATE < 9e5 /* 15 minutes */) return
+  VPN_LIST = (await (await fetch(
+    'https://raw.githubusercontent.com/X4BNet/lists_vpn/main/output/vpn/ipv4.txt',
+  )).text()).split('\n')
+  DATACENTER_LIST = (await (await fetch(
+    'https://raw.githubusercontent.com/X4BNet/lists_vpn/main/output/datacenter/ipv4.txt',
+  )).text()).split('\n')
+  LAST_UPDATE = Date.now()
+}
+
+function isIpInRange(ip: string, range: string) {
+  const [rangeIp, rangeMask] = range.split('/')
+  const rangeStart = ipToNumber(rangeIp) >>> 0
+  const rangeEnd = rangeStart + ((1 << (32 - parseInt(rangeMask))) - 1)
+  const numIp = ipToNumber(ip)
+  return numIp >= rangeStart && numIp <= rangeEnd
+}
+
+function ipToNumber(ip: string) {
+  return ip.split('.').reduce((acc, val) => (acc << 8) | parseInt(val), 0) >>> 0
+}

test/ext/firewall.test.ts

@@ -0,0 +1,61 @@
+import { assertEquals } from '../deps.ts'
+import cheetah from '../../mod.ts'
+import { firewall } from '../../ext/firewall.ts'
+
+Deno.test('ext/firewall', async (t) => {
+  await t.step('vpn', async () => {
+    const app = new cheetah({ proxy: 'cloudflare' })
+
+    app.use(firewall({
+      blockVPN: true,
+    }))
+
+    const res = await app.fetch(
+      new Request('http://localhost', {
+        headers: {
+          'cf-connecting-ip': '2.56.16.0',
+        },
+      }),
+    )
+
+    assertEquals(res.status, 403)
+  })
+})
+
+Deno.test('datacenters', async () => {
+  const app = new cheetah({ proxy: 'cloudflare' })
+
+  app.use(firewall({
+    blockDatacenter: true,
+  }))
+
+  const res = await app.fetch(
+    new Request('http://localhost', {
+      headers: {
+        'cf-connecting-ip': '1.12.32.0',
+      },
+    }),
+  )
+
+  assertEquals(res.status, 403)
+})
+
+Deno.test('customRanges', async () => {
+  const app = new cheetah({ proxy: 'cloudflare' })
+
+  app.use(firewall({
+    customRanges: [
+      '1.2.3.4/32',
+    ],
+  }))
+
+  const res = await app.fetch(
+    new Request('http://localhost', {
+      headers: {
+        'cf-connecting-ip': '1.2.3.4',
+      },
+    }),
+  )
+
+  assertEquals(res.status, 403)
+})