cache formdata boundary (#5292)

Author: KhafraDev

lib/web/fetch/body.js

@@ -7,7 +7,7 @@ const {
   fullyReadBody,
   extractMimeType
 } = require('./util')
-const { FormData, setFormDataState } = require('./formdata')
+const { FormData, setFormDataState, getFormDataBoundary } = require('./formdata')
 const { webidl } = require('../webidl')
 const assert = require('node:assert')
 const { isErrored, isDisturbed } = require('node:stream')
@@ -16,11 +16,6 @@ const { serializeAMimeType } = require('./data-url')
 const { multipartFormDataParser } = require('./formdata-parser')
 const { parseJSONFromBytes } = require('../infra')
 const { utf8DecodeBytes } = require('../../encoding')
-const { runtimeFeatures } = require('../../util/runtime-features.js')
-
-const random = runtimeFeatures.has('crypto')
-  ? require('node:crypto').randomInt
-  : (max) => Math.floor(Math.random() * max)
 
 const textEncoder = new TextEncoder()
 function noop () {}
@@ -106,7 +101,7 @@ function extractBody (object, keepalive = false) {
     // Set source to a copy of the bytes held by object.
     source = webidl.util.getCopyOfBytesHeldByBufferSource(object)
   } else if (webidl.is.FormData(object)) {
-    const boundary = `----formdata-undici-0${`${random(1e11)}`.padStart(11, '0')}`
+    const boundary = getFormDataBoundary(object)
     const prefix = `--${boundary}\r\nContent-Disposition: form-data`
 
     /*! formdata-polyfill. MIT License. Jimmy Wärting <https://jimmy.warting.se/opensource> */

lib/web/fetch/formdata.js

@@ -4,10 +4,16 @@ const { iteratorMixin } = require('./util')
 const { kEnumerableProperty } = require('../../core/util')
 const { webidl } = require('../webidl')
 const nodeUtil = require('node:util')
+const { runtimeFeatures } = require('../../util/runtime-features.js')
+
+const random = runtimeFeatures.has('crypto')
+  ? require('node:crypto').randomInt
+  : (max) => Math.floor(Math.random() * max)
 
 // https://xhr.spec.whatwg.org/#formdata
 class FormData {
   #state = []
+  #boundary = null
 
   constructor (form = undefined) {
     webidl.util.markAsUncloneable(this)
@@ -192,11 +198,24 @@ class FormData {
   static setFormDataState (formData, newState) {
     formData.#state = newState
   }
+
+  /**
+   * @param {FormData} formData
+   * @returns {string | null}
+   */
+  static getFormDataBoundary (formData) {
+    const boundary = formData.#boundary
+    if (boundary != null) return boundary
+
+    // eslint-disable-next-line no-return-assign
+    return formData.#boundary = `----formdata-undici-0${`${random(1e11)}`.padStart(11, '0')}`
+  }
 }
 
-const { getFormDataState, setFormDataState } = FormData
+const { getFormDataState, setFormDataState, getFormDataBoundary } = FormData
 Reflect.deleteProperty(FormData, 'getFormDataState')
 Reflect.deleteProperty(FormData, 'setFormDataState')
+Reflect.deleteProperty(FormData, 'getFormDataBoundary')
 
 iteratorMixin('FormData', FormData, getFormDataState, 'name', 'value')
 
@@ -256,4 +275,4 @@ function makeEntry (name, value, filename) {
 
 webidl.is.FormData = webidl.util.MakeTypeAssertion(FormData)
 
-module.exports = { FormData, makeEntry, setFormDataState }
+module.exports = { FormData, makeEntry, setFormDataState, getFormDataBoundary }

test/fetch/issue-4065.js

@@ -0,0 +1,38 @@
+'use strict'
+
+const { test } = require('node:test')
+const { once } = require('node:events')
+const { createServer } = require('node:http')
+const { fetch, FormData } = require('../..')
+
+// https://github.com/nodejs/undici/issues/4065
+test('multipart/form-data boundary is stable across a 307 redirect', async (t) => {
+  const server = createServer((req, res) => {
+    if (req.method === 'POST' && req.url === '/first') {
+      res.writeHead(307, {
+        Location: `http://localhost:${server.address().port}/second`
+      })
+      res.end()
+      return
+    }
+
+    if (req.method === 'POST' && req.url === '/second') {
+      res.setHeader('content-type', req.headers['content-type'])
+      req.pipe(res).on('end', () => res.end())
+    }
+  }).listen(0)
+
+  t.after(server.close.bind(server))
+  await once(server, 'listening')
+
+  const formData = new FormData()
+  formData.append('test', 'data')
+
+  const response = await fetch(`http://localhost:${server.address().port}/first`, {
+    method: 'POST',
+    body: formData,
+    redirect: 'follow'
+  })
+
+  await t.assert.doesNotReject(response.formData())
+})