Send CSP header in all responses

Introduces a new content security policy header for responses to all
requests to reduce the possibility of ip leaks to outside connections.
By default blocks all inline scripts, and only allows content loaded
from Whoogle.

Refactors a few small inline scripting cases in the project to their own
individual scripts.

app/__init__.py

@@ -40,6 +40,13 @@ app.config['BANG_PATH'] = os.getenv(
 app.config['BANG_FILE'] = os.path.join(
     app.config['BANG_PATH'],
     'bangs.json')
+app.config['CSP'] = 'default-src \'none\';' \
+                    'img-src \'self\';' \
+                    'style-src \'self\' \'unsafe-inline\';' \
+                    'script-src \'self\';' \
+                    'media-src \'self\';' \
+                    'connect-src \'self\';' \
+                    'form-action \'self\';'
 
 if not os.path.exists(app.config['CONFIG_PATH']):
     os.makedirs(app.config['CONFIG_PATH'])

app/routes.py

@@ -87,7 +87,7 @@ def before_request_func():
 
 
 @app.after_request
-def after_request_func(response):
+def after_request_func(resp):
     if app.user_elements[session['uuid']] <= 0 and '/element' in request.url:
         # Regenerate element key if all elements have been served to user
         session['fernet_keys'][
@@ -108,7 +108,11 @@ def after_request_func(response):
         for key in session_list:
             session.pop(key)
 
-    return response
+    resp.headers['Content-Security-Policy'] = app.config['CSP']
+    if os.environ.get('HTTPS_ONLY', False):
+        resp.headers['Content-Security-Policy'] += 'upgrade-insecure-requests'
+
+    return resp
 
 
 @app.errorhandler(404)
@@ -122,15 +126,17 @@ def unknown_page(e):
 def index():
     # Reset keys
     session['fernet_keys'] = generate_user_keys(g.cookies_disabled)
-    error_message = session[
-        'error_message'] if 'error_message' in session else ''
+
+    # Redirect if an error was raised
+    if 'error_message' in session and session['error_message']:
+        error_message = session['error_message']
         session['error_message'] = ''
+        return render_template('error.html', error_message=error_message)
 
     return render_template('index.html',
                            languages=app.config['LANGUAGES'],
                            countries=app.config['COUNTRIES'],
                            config=g.user_config,
-                           error_message=error_message,
                            tor_available=int(os.environ.get('TOR_AVAILABLE')),
                            version_number=app.config['VERSION_NUMBER'])
 
@@ -286,7 +292,9 @@ def url():
     if len(q) > 0 and 'http' in q:
         return redirect(q)
     else:
-        return render_template('error.html', query=q)
+        return render_template(
+            'error.html',
+            error_message='Unable to resolve query: ' + q)
 
 
 @app.route('/imgres')

app/static/js/header.js

@@ -0,0 +1,11 @@
+document.addEventListener("DOMContentLoaded", () => {
+    const searchBar = document.getElementById("search-bar");
+
+    searchBar.addEventListener("keyup", function (event) {
+        if (event.keyCode !== 13) {
+            handleUserInput(searchBar);
+        } else {
+            document.getElementById("search-form").submit();
+        }
+    });
+});

app/static/js/utils.js

@@ -28,7 +28,7 @@ const checkForTracking = () => {
                 /^[0-9]{15}$/
             ]
         }
-    }
+    };
     
     // Creates a link to a UPS/USPS/FedEx tracking page
     const createTrackingLink = href => {
@@ -37,7 +37,7 @@ const checkForTracking = () => {
         link.innerHTML = "View Tracking Info";
         link.href = href;
         mainDiv.prepend(link);
-    }
+    };
 
     // Compares the query against a set of regex patterns
     // for tracking numbers
@@ -48,12 +48,12 @@ const checkForTracking = () => {
                 return true;
             }
         });
-    }
+    };
 
     for (const key of Object.keys(matchTracking)) {
         compareQuery(matchTracking[key]);
     }
-}
+};
 
 document.addEventListener("DOMContentLoaded", function() {
     checkForTracking();

app/templates/error.html

@@ -1,6 +1,6 @@
 <h1>Error</h1>
 <hr>
 <p>
-    Error parsing "{{ query }}"
+    Error: "{{ error_message|safe }}"
 </p>
 <a href="/">Return Home</a>

app/templates/header.html

@@ -48,14 +48,4 @@
     </header>
 {% endif %}
 
-<script>
-    const searchBar = document.getElementById("search-bar");
-
-    searchBar.addEventListener("keyup", function (event) {
-        if (event.keyCode !== 13) {
-            handleUserInput(searchBar);
-        } else {
-            document.getElementById("search-form").submit();
-        }
-    });
-</script>
+<script type="text/javascript" src="static/js/header.js"></script>

app/templates/index.html

@@ -36,12 +36,6 @@
         <title>Whoogle Search</title>
     </head>
     <body id="main" style="display: none; background-color: {{ '#000' if config.dark else '#fff' }}">
-    <script>
-        {% if error_message|length > 0 %}
-            let error = "{{ error_message|safe }}";
-            alert(error);
-        {% endif %}
-    </script>
         <div class="search-container">
             <img class="logo" src="static/img/logo.png">
             <form id="search-form" action="search" method="{{ 'get' if config.get_only else 'post' }}">