do not strip TE headers if trailing (#443)

Author: gunters63

lib/utils.js

@@ -42,12 +42,17 @@ function stripHttp1ConnectionHeaders (headers) {
       case 'connection':
       case 'upgrade':
       case 'http2-settings':
-      case 'te':
       case 'transfer-encoding':
       case 'proxy-connection':
       case 'keep-alive':
       case 'host':
         break
+      case 'te':
+        // see illegal connection specific header handling in Node.js
+        if (headers['te'] === 'trailers') {
+          dest[header] = headers[header]
+        }
+        break
       default:
         dest[header] = headers[header]
         break

test/http2-te-header-not-stripped-if-trailing.test.js

@@ -0,0 +1,60 @@
+'use strict'
+const h2url = require('h2url')
+const t = require('node:test')
+const Fastify = require('fastify')
+const From = require('..')
+const fs = require('node:fs')
+const path = require('node:path')
+const certs = {
+  key: fs.readFileSync(path.join(__dirname, 'fixtures', 'fastify.key')),
+  cert: fs.readFileSync(path.join(__dirname, 'fixtures', 'fastify.cert'))
+}
+
+t.test('do not strip te header if set to trailing', async (t) => {
+  const instance = Fastify({
+    http2: true,
+    https: certs
+  })
+
+  t.after(() => instance.close())
+
+  const target = Fastify({
+    http2: true
+  })
+
+  target.get('/', (request, reply) => {
+    t.assert.strictEqual(request.headers['te'], 'trailers')
+
+    reply.send({
+      hello: 'world'
+    })
+  })
+
+  instance.get('/', (_request, reply) => {
+    reply.from()
+  })
+
+  t.after(() => target.close())
+
+  await target.listen({ port: 0 })
+
+  instance.register(From, {
+    base: `http://localhost:${target.server.address().port}`,
+    http2: true,
+    rejectUnauthorized: false
+  })
+
+  await instance.listen({ port: 0 })
+
+  const { headers } = await h2url.concat({
+    url: `https://localhost:${instance.server.address().port}`,
+    headers: {
+      te: 'trailers'
+    }
+  })
+
+  t.assert.strictEqual(headers[':status'], 200)
+
+  instance.close()
+  target.close()
+})