chore: add security headers

scripts/security-headers.js

@@ -0,0 +1,77 @@
+'use strict'
+
+const { writeFile } = require('fs').promises
+const { once } = require('events')
+const helmet = require('helmet')()
+const http = require('http')
+
+const listen = async (server, ...args) => {
+  server.listen(...args)
+  await once(server, 'listening')
+  const { address, port, family } = server.address()
+  return `http://${family === 'IPv6' ? `[${address}]` : address}:${port}/`
+}
+
+const createServer = ({ withHelmet = false } = {}) =>
+  http.createServer((req, res) => {
+    const fn = withHelmet ? helmet : (req, res, next) => next()
+    fn(req, res, err => {
+      if (err) {
+        res.statusCode = 500
+        res.end(
+          'Helmet failed for some unexpected reason. Was it configured correctly?'
+        )
+        return
+      }
+      res.end('Hello world!')
+    })
+  })
+
+const getSecurityHeaders = async () => {
+  let server = createServer({ withHelmet: false })
+
+  let serverUrl = await listen(server)
+
+  let res = await fetch(serverUrl)
+  const headers = Object.fromEntries(res.headers)
+
+  server.close()
+
+  server = createServer({ withHelmet: true })
+  serverUrl = await listen(server)
+
+  res = await fetch(serverUrl)
+  const headersWithHelmet = Object.fromEntries(res.headers)
+
+  server.close()
+
+  const diff = Object.fromEntries(
+    Object.entries(headersWithHelmet).filter(
+      ([key, value]) => headers[key] !== value
+    )
+  )
+
+  return Object.entries(diff).map(([key, value]) => ({ key, value }))
+}
+
+;(async () => {
+  const SOURCE_PATTERN = '/(.*)'
+  const headers = await getSecurityHeaders()
+
+  const vercelJSON = require('../vercel.json')
+
+  if (!vercelJSON.headers) {
+    vercelJSON.headers = [
+      {
+        source: SOURCE_PATTERN,
+        headers
+      }
+    ]
+  } else {
+    const rule = vercelJSON.headers.find(rule => rule.source === SOURCE_PATTERN)
+    if (!rule) vercelJSON.headers.push({ source: SOURCE_PATTERN, headers })
+    else rule.headers = headers
+  }
+
+  await writeFile('vercel.json', JSON.stringify(vercelJSON, null, 2))
+})()

vercel.json

@@ -1,4 +1,59 @@
 {
+  "headers": [
+    {
+      "source": "/(.*)",
+      "headers": [
+        {
+          "key": "content-security-policy",
+          "value": "default-src 'self';base-uri 'self';font-src 'self' https: data:;form-action 'self';frame-ancestors 'self';img-src 'self' data:;object-src 'none';script-src 'self';script-src-attr 'none';style-src 'self' https: 'unsafe-inline';upgrade-insecure-requests"
+        },
+        {
+          "key": "cross-origin-opener-policy",
+          "value": "same-origin"
+        },
+        {
+          "key": "cross-origin-resource-policy",
+          "value": "same-origin"
+        },
+        {
+          "key": "origin-agent-cluster",
+          "value": "?1"
+        },
+        {
+          "key": "referrer-policy",
+          "value": "no-referrer"
+        },
+        {
+          "key": "strict-transport-security",
+          "value": "max-age=15552000; includeSubDomains"
+        },
+        {
+          "key": "x-content-type-options",
+          "value": "nosniff"
+        },
+        {
+          "key": "x-dns-prefetch-control",
+          "value": "off"
+        },
+        {
+          "key": "x-download-options",
+          "value": "noopen"
+        },
+        {
+          "key": "x-frame-options",
+          "value": "SAMEORIGIN"
+        },
+        {
+          "key": "x-permitted-cross-domain-policies",
+          "value": "none"
+        },
+        {
+          "key": "x-xss-protection",
+          "value": "0"
+        }
+      ]
+    }
+  ],
   "redirects": [
     {
       "source": "/adblock",
@@ -197,4 +252,4 @@
       "destination": "/docs/api/parameters/waitUntil"
     }
   ]
-}
+}