Do not set the compress onSend hook twice (#141)

* Do not set the compress onSend hook twice

Fixes #140

* fixup

* Update test/test-routes-compress.js

Co-authored-by: Manuel Spigolon <[email protected]>

Co-authored-by: Manuel Spigolon <[email protected]>

Author: mcollina

index.js

@@ -19,6 +19,8 @@ const { inherits, format } = require('util')
 const InvalidRequestEncodingError = createError('FST_CP_ERR_INVALID_CONTENT_ENCODING', 'Unsupported Content-Encoding: %s', 415)
 const InvalidRequestCompressedPayloadError = createError('FST_CP_ERR_INVALID_CONTENT', 'Could not decompress the request payload using the provided encoding', 400)
 
+const compressAdded = Symbol('fastify-compress.added')
+
 function compressPlugin (fastify, opts, next) {
   const globalCompressParams = processCompressParams(opts)
   const globalDecompressParams = processDecompressParams(opts)
@@ -179,6 +181,16 @@ function processDecompressParams (opts) {
 }
 
 function buildRouteCompress (fastify, params, routeOptions, decorateOnly) {
+  // This methods works by altering the routeOptions, it has side effects.
+  // There is the possibility that the same options are set for more than
+  // one route, so we just need to make sure that the hook is addded only
+  // once.
+  if (routeOptions[compressAdded]) {
+    return
+  }
+
+  routeOptions[compressAdded] = true
+
   // In order to provide a compress method with the same parameter set as the route itself has
   // we do the decorate the reply at the start of the request
   if (Array.isArray(routeOptions.onRequest)) {

test/test-routes-compress.js

@@ -255,3 +255,30 @@ test('should throw an error on invalid compression setting', t => {
     t.strictEqual(err.message, 'Unknown value for route compress configuration')
   })
 })
+
+test('avoid double onSend', t => {
+  t.plan(2)
+
+  const server = Fastify()
+
+  server.register(compressPlugin, {
+    threshold: 0
+  })
+
+  server.register(async function (server) {
+    server.get('/', async (req, _) => {
+      return { hi: true }
+    })
+  }, { prefix: '/test' })
+
+  server.inject({
+    url: '/test',
+    method: 'GET',
+    headers: {
+      'accept-encoding': 'br'
+    }
+  }, (err, res) => {
+    t.error(err)
+    t.deepEqual(JSON.parse(zlib.brotliDecompressSync(res.rawPayload)), { hi: true })
+  })
+})