test(lib): add a test for the X-Forwarded-For middleware

Previously the X-Forwarded-For middleware could return two commas in a
row. This is a regression test to make sure that doesn't happen again.

Imports a patch previously exclusive to Botstopper.

Signed-off-by: Xe Iaso <me@xeiaso.net>

VERSION

@@ -1 +1 @@
-1.21.2
+1.21.3

docs/docs/CHANGELOG.md

@@ -13,18 +13,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- This changes the project to: -->
 
-## v1.21.2: Minfilia Warde - Echo 2
+## v1.21.3: Minfilia Warde - Echo 3
 
 ### Fixes
 
 #### Fixes a problem with nonstandard URLs and redirects
 
+Fixes [GHSA-jhjj-2g64-px7c](https://github.com/TecharoHQ/anubis/security/advisories/GHSA-jhjj-2g64-px7c).
+
 This could allow an attacker to craft an Anubis pass-challenge URL that forces a redirect to nonstandard URLs, such as the `javascript:` scheme which executes arbitrary JavaScript code in a browser context when the user clicks the "Try again" button.
 
 This has been fixed by disallowing any URLs without the scheme `http` or `https`.
 
 Additionally, the "Try again" button has been fixed to completely ignore the user-supplied redirect location. It now redirects to the home page (`/`).
 
+## v1.21.2: Minfilia Warde - Echo 2
+
+This contained an incomplete fix for [GHSA-jhjj-2g64-px7c](https://github.com/TecharoHQ/anubis/security/advisories/GHSA-jhjj-2g64-px7c). Do not use this version.
+
 ## v1.21.1: Minfilia Warde - Echo 1
 
 - Expired records are now properly removed from bbolt databases ([#848](https://github.com/TecharoHQ/anubis/pull/848)).

lib/anubis_test.go

@@ -926,3 +926,42 @@ func TestPassChallengeXSS(t *testing.T) {
 		}
 	})
 }
+
+func TestXForwardedForNoDoubleComma(t *testing.T) {
+	var h http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("X-Forwarded-For", r.Header.Get("X-Forwarded-For"))
+		fmt.Fprintln(w, "OK")
+	})
+
+	h = internal.XForwardedForToXRealIP(h)
+	h = internal.XForwardedForUpdate(false, h)
+
+	pol := loadPolicies(t, "testdata/permissive.yaml", 4)
+
+	srv := spawnAnubis(t, Options{
+		Next:   h,
+		Policy: pol,
+	})
+	ts := httptest.NewServer(srv)
+	t.Cleanup(ts.Close)
+
+	req, err := http.NewRequest(http.MethodGet, ts.URL, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	req.Header.Set("X-Real-Ip", "10.0.0.1")
+
+	resp, err := ts.Client().Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("response status is wrong, wanted %d but got: %s", http.StatusOK, resp.Status)
+	}
+
+	if xff := resp.Header.Get("X-Forwarded-For"); strings.HasPrefix(xff, ",,") {
+		t.Errorf("X-Forwarded-For has two leading commas: %q", xff)
+	}
+}

lib/testdata/permissive.yaml

@@ -0,0 +1,4 @@
+bots:
+  - import: (data)/common/allow-private-addresses.yaml
+
+dnsbl: false

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@techaro/anubis",
-  "version": "1.21.2",
+  "version": "1.21.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@techaro/anubis",
-      "version": "1.21.2",
+      "version": "1.21.3",
       "license": "ISC",
       "devDependencies": {
         "cssnano": "^7.1.0",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@techaro/anubis",
-  "version": "1.21.2",
+  "version": "1.21.3",
   "description": "",
   "main": "index.js",
   "scripts": {