Add optional support for a simple CAPTCHA. (#844)

* Add optional support for a simple CAPTCHA.
* formatting
* add test case
* Flake8

Co-authored-by: Glandos <bugs-github@antipoul.fr>

docs/configuration.rst

@@ -155,6 +155,11 @@ Note: this setting is actually interpreted by Flask-Babel, see the
 
 .. _Flask-Babel guide for formatting dates: https://pythonhosted.org/Flask-Babel/#formatting-dates
 
+`ENABLE_CAPTCHA`
+---------------
+
+It is possible to add a simple captcha in order to filter out spammer bots on the form creation.
+In order to do so, you just have to set `ENABLE_CAPTCHA = True`.
 
 Configuring emails sending
 --------------------------

ihatemoney/conf-templates/ihatemoney.cfg.j2

@@ -42,3 +42,7 @@ ACTIVATE_ADMIN_DASHBOARD = False
 # Enable secure cookies. Requires HTTPS. Disable if you run your ihatemoney
 # service over plain HTTP.
 SESSION_COOKIE_SECURE = True
+
+# You can activate an optional CAPTCHA if you want to. It can be helpful
+# to filter spammer bots.
+# ENABLE_CAPTCHA = True

ihatemoney/default_settings.py

@@ -32,3 +32,4 @@ SUPPORTED_LANGUAGES = [
     "uk",
     "zh_Hans",
 ]
+ENABLE_CAPTCHA = False

ihatemoney/forms.py

@@ -221,6 +221,19 @@ class ProjectForm(EditProjectForm):
             )
             raise ValidationError(Markup(message))
 
+    @classmethod
+    def enable_captcha(cls):
+        captchaField = StringField(
+            _("Which is a real currency: Euro or Petro dollar?"),
+            validators=[DataRequired()],
+        )
+        setattr(cls, "captcha", captchaField)
+
+    def validate_captcha(form, field):
+        if not field.data.lower() == _("euro"):
+            message = _("Please, validate the captcha to proceed.")
+            raise ValidationError(Markup(message))
+
 
 class DestructiveActionProjectForm(FlaskForm):
     """Used for any important "delete" action linked to a project:

ihatemoney/templates/forms.html

@@ -75,6 +75,9 @@
     {{ input(form.name) }}
     {{ input(form.password) }}
     {{ input(form.contact_email) }}
+    {% if config['ENABLE_CAPTCHA'] %}
+    {{ input(form.captcha) }}
+    {% endif %}
     {{ input(form.default_currency) }}
     {% if not home %}
     {{ submit(form.submit, home=True) }}
@@ -171,7 +174,7 @@
             </div>
         </div>
     </div>
-    
+
     <details class="mb-3">
         <summary class="mb-2">{{ _("More options") }}</summary>
         {% if g.project.default_currency != "XXX" %}

ihatemoney/tests/common/ihatemoney_testcase.py

@@ -15,6 +15,7 @@ class BaseTestCase(TestCase):
     SQLALCHEMY_DATABASE_URI = os.environ.get(
         "TESTING_SQLALCHEMY_DATABASE_URI", "sqlite://"
     )
+    ENABLE_CAPTCHA = False
 
     def create_app(self):
         # Pass the test object as a configuration.

ihatemoney/tests/main_test.py

@@ -31,6 +31,7 @@ class ConfigurationTestCase(BaseTestCase):
         self.assertTrue(self.app.config["ACTIVATE_DEMO_PROJECT"])
         self.assertTrue(self.app.config["ALLOW_PUBLIC_PROJECT_CREATION"])
         self.assertFalse(self.app.config["ACTIVATE_ADMIN_DASHBOARD"])
+        self.assertFalse(self.app.config["ENABLE_CAPTCHA"])
 
     def test_env_var_configuration_file(self):
         """Test that settings are loaded from a configuration file specified
@@ -241,6 +242,50 @@ class EmailFailureTestCase(IhatemoneyTestCase):
             )
 
 
+class CaptchaTestCase(IhatemoneyTestCase):
+    ENABLE_CAPTCHA = True
+
+    def test_project_creation_with_captcha(self):
+        with self.app.test_client() as c:
+            c.post(
+                "/create",
+                data={
+                    "name": "raclette party",
+                    "id": "raclette",
+                    "password": "party",
+                    "contact_email": "raclette@notmyidea.org",
+                    "default_currency": "USD",
+                },
+            )
+            assert len(models.Project.query.all()) == 0
+
+            c.post(
+                "/create",
+                data={
+                    "name": "raclette party",
+                    "id": "raclette",
+                    "password": "party",
+                    "contact_email": "raclette@notmyidea.org",
+                    "default_currency": "USD",
+                    "captcha": "nope",
+                },
+            )
+            assert len(models.Project.query.all()) == 0
+
+            c.post(
+                "/create",
+                data={
+                    "name": "raclette party",
+                    "id": "raclette",
+                    "password": "party",
+                    "contact_email": "raclette@notmyidea.org",
+                    "default_currency": "USD",
+                    "captcha": "euro",
+                },
+            )
+            assert len(models.Project.query.all()) == 1
+
+
 class TestCurrencyConverter(unittest.TestCase):
     converter = CurrencyConverter()
     mock_data = {"USD": 1, "EUR": 0.8, "CAD": 1.2, CurrencyConverter.no_currency: 1}

ihatemoney/web.py

@@ -260,9 +260,16 @@ def authenticate(project_id=None):
     return render_template("authenticate.html", form=form)
 
 
+def get_project_form():
+    if current_app.config.get("ENABLE_CAPTCHA", False):
+        ProjectForm.enable_captcha()
+
+    return ProjectForm()
+
+
 @main.route("/", strict_slashes=False)
 def home():
-    project_form = ProjectForm()
+    project_form = get_project_form()
     auth_form = AuthenticationForm()
     is_demo_project_activated = current_app.config["ACTIVATE_DEMO_PROJECT"]
     is_public_project_creation_allowed = current_app.config[
@@ -287,7 +294,7 @@ def mobile():
 @main.route("/create", methods=["GET", "POST"])
 @requires_admin(bypass=("ALLOW_PUBLIC_PROJECT_CREATION", True))
 def create_project():
-    form = ProjectForm()
+    form = get_project_form()
     if request.method == "GET" and "project_id" in request.values:
         form.name.data = request.values["project_id"]