feat: Add allowInsecureRedirect option

BREAKING CHANGE: The allowInsecureRedirect is `false` by default, which may cause issues if your usage relies on insecure redirects. For the former behavior, you can opt in to insecure redirects by setting the option to `true`, but it is not recommended. 

Co-authored-by: Szymon Drosdzol <szymon@doyensec.com>

README.md

@@ -707,6 +707,7 @@ The first argument can be either a `url` or an `options` object. The only requir
 - `followOriginalHttpMethod` - by default we redirect to HTTP method GET. you can enable this property to redirect to the original HTTP method (default: `false`)
 - `maxRedirects` - the maximum number of redirects to follow (default: `10`)
 - `removeRefererHeader` - removes the referer header when a redirect happens (default: `false`). **Note:** if true, referer header set in the initial request is preserved during redirect chain.
+- `allowInsecureRedirect` - allows cross-protocol redirects (HTTP to HTTPS and vice versa). **Warning:** may lead to bypassing anti SSRF filters (default: `false`)
 
 ---
 

lib/redirect.js

@@ -14,6 +14,7 @@ function Redirect (request) {
   this.redirects = []
   this.redirectsFollowed = 0
   this.removeRefererHeader = false
+  this.allowInsecureRedirect = false
 }
 
 Redirect.prototype.onRequest = function (options) {
@@ -40,6 +41,9 @@ Redirect.prototype.onRequest = function (options) {
   if (options.followOriginalHttpMethod !== undefined) {
     self.followOriginalHttpMethod = options.followOriginalHttpMethod
   }
+  if (options.allowInsecureRedirect !== undefined) {
+    self.allowInsecureRedirect = options.allowInsecureRedirect
+  }
 }
 
 Redirect.prototype.redirectTo = function (response) {
@@ -113,7 +117,7 @@ Redirect.prototype.onResponse = function (response, callback) {
     request.uri = url.parse(redirectTo)
 
     // handle the case where we change protocol from https to http or vice versa
-    if (request.uri.protocol !== uriPrev.protocol) {
+    if (request.uri.protocol !== uriPrev.protocol && self.allowInsecureRedirect) {
       delete request.agent
     }
 

tests/test-httpModule.js

@@ -70,7 +70,7 @@ function runTests (name, httpModules) {
   tape(name, function (t) {
     var toHttps = 'http://localhost:' + plainServer.port + '/to_https'
     var toPlain = 'https://localhost:' + httpsServer.port + '/to_plain'
-    var options = { httpModules: httpModules, strictSSL: false }
+    var options = { httpModules: httpModules, strictSSL: false, allowInsecureRedirect: true }
     var modulesTest = httpModules || {}
 
     clearFauxRequests()

tests/test-redirect-auth.js

@@ -18,6 +18,7 @@ request = request.defaults({
     user: 'test',
     pass: 'testing'
   },
+  allowInsecureRedirect: true,
   rejectUnauthorized: false
 })
 

tests/test-redirect-complex.js

@@ -67,6 +67,7 @@ tape('lots of redirects', function (t) {
     request({
       url: (i % 2 ? s.url : ss.url) + '/a',
       headers: { 'x-test-key': key },
+      allowInsecureRedirect: true,
       rejectUnauthorized: false
     }, function (err, res, body) {
       t.equal(err, null)

tests/test-redirect.js

@@ -445,7 +445,8 @@ tape('http to https redirect', function (t) {
   hits = {}
   request.get({
     uri: require('url').parse(s.url + '/ssl'),
-    rejectUnauthorized: false
+    rejectUnauthorized: false,
+    allowInsecureRedirect: true
   }, function (err, res, body) {
     t.equal(err, null)
     t.equal(res.statusCode, 200)
@@ -454,6 +455,18 @@ tape('http to https redirect', function (t) {
   })
 })
 
+tape('http to https redirect should fail without the explicit "allowInsecureRedirect" option', function (t) {
+  hits = {}
+  request.get({
+    uri: require('url').parse(s.url + '/ssl'),
+    rejectUnauthorized: false
+  }, function (err, res, body) {
+    t.notEqual(err, null)
+    t.equal(err.code, 'ERR_INVALID_PROTOCOL', 'Failed to cross-protocol redirect')
+    t.end()
+  })
+})
+
 tape('should have referer header by default when following redirect', function (t) {
   request.post({
     uri: s.url + '/temp',

tests/test-tunnel.js

@@ -356,6 +356,7 @@ function addTests () {
     'https->http over http, tunnel=true',
     {
       url: ss.url + '/redirect/http',
+      allowInsecureRedirect: true,
       proxy: s.url,
       tunnel: true
     },
@@ -372,6 +373,7 @@ function addTests () {
     'https->http over http, tunnel=false',
     {
       url: ss.url + '/redirect/http',
+      allowInsecureRedirect: true,
       proxy: s.url,
       tunnel: false
     },
@@ -388,6 +390,7 @@ function addTests () {
     'https->http over http, tunnel=default',
     {
       url: ss.url + '/redirect/http',
+      allowInsecureRedirect: true,
       proxy: s.url
     },
     [