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1'use strict'2 3const { FetchError, Request, isRedirect } = require('minipass-fetch')4const url = require('url')5 6const CachePolicy = require('./cache/policy.js')7const cache = require('./cache/index.js')8const remote = require('./remote.js')9 10// given a Request, a Response and user options11// return true if the response is a redirect that12// can be followed. we throw errors that will result13// in the fetch being rejected if the redirect is14// possible but invalid for some reason15const canFollowRedirect = (request, response, options) => {16  if (!isRedirect(response.status)) {17    return false18  }19 20  if (options.redirect === 'manual') {21    return false22  }23 24  if (options.redirect === 'error') {25    throw new FetchError(`redirect mode is set to error: ${request.url}`,26      'no-redirect', { code: 'ENOREDIRECT' })27  }28 29  if (!response.headers.has('location')) {30    throw new FetchError(`redirect location header missing for: ${request.url}`,31      'no-location', { code: 'EINVALIDREDIRECT' })32  }33 34  if (request.counter >= request.follow) {35    throw new FetchError(`maximum redirect reached at: ${request.url}`,36      'max-redirect', { code: 'EMAXREDIRECT' })37  }38 39  return true40}41 42// given a Request, a Response, and the user's options return an object43// with a new Request and a new options object that will be used for44// following the redirect45const getRedirect = (request, response, options) => {46  const _opts = { ...options }47  const location = response.headers.get('location')48  const redirectUrl = new url.URL(location, /^https?:/.test(location) ? undefined : request.url)49  // Comment below is used under the following license:50  /**51   * @license52   * Copyright (c) 2010-2012 Mikeal Rogers53   * Licensed under the Apache License, Version 2.0 (the "License");54   * you may not use this file except in compliance with the License.55   * You may obtain a copy of the License at56   * http://www.apache.org/licenses/LICENSE-2.057   * Unless required by applicable law or agreed to in writing,58   * software distributed under the License is distributed on an "AS59   * IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either60   * express or implied. See the License for the specific language61   * governing permissions and limitations under the License.62   */63 64  // Remove authorization if changing hostnames (but not if just65  // changing ports or protocols).  This matches the behavior of request:66  // https://github.com/request/request/blob/b12a6245/lib/redirect.js#L134-L13867  if (new url.URL(request.url).hostname !== redirectUrl.hostname) {68    request.headers.delete('authorization')69    request.headers.delete('cookie')70  }71 72  // for POST request with 301/302 response, or any request with 303 response,73  // use GET when following redirect74  if (75    response.status === 303 ||76    (request.method === 'POST' && [301, 302].includes(response.status))77  ) {78    _opts.method = 'GET'79    _opts.body = null80    request.headers.delete('content-length')81  }82 83  _opts.headers = {}84  request.headers.forEach((value, key) => {85    _opts.headers[key] = value86  })87 88  _opts.counter = ++request.counter89  const redirectReq = new Request(url.format(redirectUrl), _opts)90  return {91    request: redirectReq,92    options: _opts,93  }94}95 96const fetch = async (request, options) => {97  const response = CachePolicy.storable(request, options)98    ? await cache(request, options)99    : await remote(request, options)100 101  // if the request wasn't a GET or HEAD, and the response102  // status is between 200 and 399 inclusive, invalidate the103  // request url104  if (!['GET', 'HEAD'].includes(request.method) &&105      response.status >= 200 &&106      response.status <= 399) {107    await cache.invalidate(request, options)108  }109 110  if (!canFollowRedirect(request, response, options)) {111    return response112  }113 114  const redirect = getRedirect(request, response, options)115  return fetch(redirect.request, redirect.options)116}117 118module.exports = fetch119