http: disallow two-byte characters in URL path

CVE-2018-12116
Backport of b961d9f to 8.x

Original commit:
  This commit changes node's handling of two-byte characters in
  the path component of an http URL. Previously, node would just
  strip the higher byte when generating the request. So this code:

  ```
  http.request({host: "example.com", port: "80", "/Ｎ"})
  ```

  would request `http://example.com/.`
  (`.` is the character for the byte `0x2e`).

  This is not useful and can in some cases lead to filter evasion.
  With this change, the code generates `ERR_UNESCAPED_CHARACTERS`,
  just like space and control characters already did.

  PR-URL: #16237
  Reviewed-By: James M Snell <jasnell@gmail.com>
  Reviewed-By: Anna Henningsen <anna@addaleax.net>
  Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
  Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
  Reviewed-By: Timothy Gu <timothygu99@gmail.com>

PR-URL: nodejs-private/node-private#146
Fixes: nodejs-private/security#207
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/_http_client.js

@@ -41,33 +41,7 @@ const { outHeadersKey, ondrain } = require('internal/http');
 const { nextTick } = require('internal/process/next_tick');
 const is_reused_symbol = require('internal/freelist').symbols.is_reused_symbol;
 
-// The actual list of disallowed characters in regexp form is more like:
-//    /[^A-Za-z0-9\-._~!$&'()*+,;=/:@]/
-// with an additional rule for ignoring percentage-escaped characters, but
-// that's a) hard to capture in a regular expression that performs well, and
-// b) possibly too restrictive for real-world usage. So instead we restrict the
-// filter to just control characters and spaces.
-//
-// This function is used in the case of small paths, where manual character code
-// checks can greatly outperform the equivalent regexp (tested in V8 5.4).
-function isInvalidPath(s) {
-  var i = 0;
-  if (s.charCodeAt(0) <= 32) return true;
-  if (++i >= s.length) return false;
-  if (s.charCodeAt(1) <= 32) return true;
-  if (++i >= s.length) return false;
-  if (s.charCodeAt(2) <= 32) return true;
-  if (++i >= s.length) return false;
-  if (s.charCodeAt(3) <= 32) return true;
-  if (++i >= s.length) return false;
-  if (s.charCodeAt(4) <= 32) return true;
-  if (++i >= s.length) return false;
-  if (s.charCodeAt(5) <= 32) return true;
-  ++i;
-  for (; i < s.length; ++i)
-    if (s.charCodeAt(i) <= 32) return true;
-  return false;
-}
+const INVALID_PATH_REGEX = /[^\u0021-\u00ff]/;
 
 function validateHost(host, name) {
   if (host != null && typeof host !== 'string') {
@@ -118,13 +92,7 @@ function ClientRequest(options, cb) {
   var path;
   if (options.path) {
     path = String(options.path);
-    var invalidPath;
-    if (path.length <= 39) { // Determined experimentally in V8 5.4
-      invalidPath = isInvalidPath(path);
-    } else {
-      invalidPath = /[\u0000-\u0020]/.test(path);
-    }
-    if (invalidPath)
+    if (INVALID_PATH_REGEX.test(path))
       throw new TypeError('Request path contains unescaped characters');
   }
 

test/parallel/test-http-client-invalid-path.js

@@ -0,0 +1,12 @@
+'use strict';
+
+require('../common');
+
+const http = require('http');
+const assert = require('assert');
+
+assert.throws(() => {
+  http.request({
+    path: '/thisisinvalid\uffe2'
+  }).end();
+}, /Request path contains unescaped characters/);