Merge pull request #46 from frontfoot/404_to_bots

Return 404 to UserAgents matching /bot/

snappass/main.py

@@ -1,4 +1,5 @@
 import os
+import re
 import sys
 import uuid
 
@@ -8,6 +9,8 @@ from redis.exceptions import ConnectionError
 from flask import abort, Flask, render_template, request
 
 
+SNEAKY_USER_AGENTS = ('Slackbot', 'facebookexternalhit', 'Twitterbot', 'Facebot', 'WhatsApp')
+SNEAKY_USER_AGENTS_RE = re.compile('|'.join(SNEAKY_USER_AGENTS))
 NO_SSL = os.environ.get('NO_SSL', False)
 app = Flask(__name__)
 if os.environ.get('DEBUG'):
@@ -80,6 +83,13 @@ def clean_input():
 
     return time_conversion[time_period], request.form['password']
 
+def request_is_valid(request):
+    """
+    Ensure the request validates the following:
+        - not made by some specific User-Agents (to avoid chat's preview feature issue)
+    """
+    return not SNEAKY_USER_AGENTS_RE.search(request.headers.get('User-Agent', ''))
+
 
 @app.route('/', methods=['GET'])
 def index():
@@ -101,6 +111,8 @@ def handle_password():
 
 @app.route('/<password_key>', methods=['GET'])
 def show_password(password_key):
+    if not request_is_valid(request):
+        abort(404)
     password = get_password(password_key)
     if not password:
         abort(404)

tests.py

@@ -73,6 +73,25 @@ class SnapPassRoutesTestCase(TestCase):
         rv = self.app.get('/{0}'.format(key))
         self.assertTrue(password in rv.get_data(as_text=True))
 
+    def test_bots_denial(self):
+        """
+        Main known bots User-Agent should be denied access
+        """
+        password = "Bots can't access this"
+        key = snappass.set_password(password, 30)
+        a_few_sneaky_bots = [
+            "Slackbot-LinkExpanding 1.0 (+https://api.slack.com/robots)",
+            "facebookexternalhit/1.1",
+            "Facebot/1.0",
+            "Twitterbot/1.0",
+            "_WhatsApp/2.12.81 (Windows NT 6.1; U; es-ES) Presto/2.9.181 Version/12.00",
+            "WhatsApp/2.16.6/i"
+        ]
+
+        for ua in a_few_sneaky_bots:
+            rv = self.app.get('/{0}'.format(key), headers={ 'User-Agent': ua })
+            self.assertEquals(rv.status_code, 404)
+
 
 if __name__ == '__main__':
     unittest.main()