Fix download forgery

app/__init__.py

@@ -25,13 +25,15 @@ from flask_github import GitHub
 from flask_wtf.csrf import CsrfProtect
 from flask_flatpages import FlatPages
 from flask_babel import Babel
-import os
+import os, redis
 
 app = Flask(__name__, static_folder="public/static")
 app.config["FLATPAGES_ROOT"] = "flatpages"
 app.config["FLATPAGES_EXTENSION"] = ".md"
 app.config.from_pyfile(os.environ["FLASK_CONFIG"])
 
+r = redis.Redis.from_url(app.config["REDIS_URL"])
+
 menu.Menu(app=app)
 markdown = Markdown(app, extensions=["fenced_code"], safe_mode=True, output_format="html5")
 github = GitHub(app)

app/blueprints/packages/releases.py

@@ -20,6 +20,7 @@ from flask_user import *
 
 from . import bp
 
+from app.rediscache import has_key, set_key, make_download_key
 from app.models import *
 from app.tasks.importtasks import makeVCSRelease
 from app.utils import *
@@ -123,14 +124,12 @@ def download_release(package, id):
 	if release is None or release.package != package:
 		abort(404)
 
-	if release is None:
+	ip = request.headers.get("X-Forwarded-For") or request.remote_addr
-		if "application/zip" in request.accept_mimetypes and \
+	if ip is not None:
-				not "text/html" in request.accept_mimetypes:
+		key = make_download_key(ip, release.package)
-			return "", 204
+		if not has_key(key):
-		else:
+			set_key(key, "true")
-			flash("No download available.", "error")
+
-			return redirect(package.getDetailsURL())
-	else:
 			PackageRelease.query.filter_by(id=release.id).update({
 					"downloads": PackageRelease.downloads + 1
 				})

app/rediscache.py

@@ -0,0 +1,13 @@
+from . import r
+
+# This file acts as a facade between the releases code and redis,
+# and also means that the releases code avoids knowing about `app`
+
+def make_download_key(ip, package):
+	return ("{}/{}/{}").format(ip, package.author.username, package.name)
+
+def set_key(key, v):
+	r.set(key, v)
+
+def has_key(key):
+	return r.exists(key)

config.example.cfg

@@ -10,8 +10,9 @@ SQLALCHEMY_DATABASE_URI = "sqlite:///../db.sqlite"
 GITHUB_CLIENT_ID = ""
 GITHUB_CLIENT_SECRET = ""
 
-CELERY_BROKER_URL='redis://localhost:6379'
+REDIS_URL='redis://redis:6379'
-CELERY_RESULT_BACKEND='redis://localhost:6379'
+CELERY_BROKER_URL='redis://redis:6379'
+CELERY_RESULT_BACKEND='redis://redis:6379'
 
 USER_ENABLE_REGISTER = False
 USER_ENABLE_CHANGE_USERNAME = False

requirements.txt

@@ -16,7 +16,7 @@ celery==4.1.1
 kombu==4.2.0
 GitPython~=2.1
 lxml~=4.2
-pillow~=5.3
+pillow~=6.2
 pyScss~=1.3
 redis==2.10.6
 psycopg2~=2.7