coturn: Validate TURN URIs if provided in form

Signed-off-by: James Valleroy <jvalleroy@mailbox.org>

- Re-use the same validator in Matrix Synapse.
- Avoid importing plinth classes in actions files.
Signed-off-by: Joseph Nuthalapati <njoseph@riseup.net>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

actions/ejabberd

@@ -30,6 +30,8 @@ yaml = YAML()
 yaml.allow_duplicate_keys = True
 yaml.preserve_quotes = True
 
+TURN_URI_REGEX = r'(stun|turn):(.*):([0-9]{4})\?transport=(tcp|udp)'
+
 
 def parse_arguments():
     """Return parsed command line arguments as dictionary"""
@@ -303,7 +305,7 @@ def subcommand_mam(argument):
 
 def _generate_service(uri: str) -> dict:
     """Generate ejabberd mod_stun_disco service config from Coturn URI."""
-    pattern = re.compile(r'(stun|turn):(.*):([0-9]{4})\?transport=(tcp|udp)')
+    pattern = re.compile(TURN_URI_REGEX)
     typ, domain, port, transport = pattern.match(uri).groups()
     return {
         "host": domain,

plinth/modules/coturn/components.py

@@ -5,10 +5,13 @@
 from __future__ import annotations  # Can be removed in Python 3.10
 
 import json
+import re
 from dataclasses import dataclass, field
 
 from plinth import app
 
+TURN_URI_REGEX = r'(stun|turn):(.*):([0-9]{4})\?transport=(tcp|udp)'
+
 
 @dataclass
 class TurnConfiguration:
@@ -45,6 +48,12 @@ class TurnConfiguration:
             'shared_secret': self.shared_secret
         })
 
+    @staticmethod
+    def validate_turn_uris(turn_uris: list[str]) -> bool:
+        """Return whether the given TURN URI is valid."""
+        pattern = re.compile(TURN_URI_REGEX)
+        return all(map(pattern.match, turn_uris))
+
 
 class TurnConsumer(app.FollowerComponent):
     """Component to manage coturn configuration.

plinth/modules/coturn/forms.py

@@ -4,9 +4,11 @@ Forms for Coturn app.
 """
 
 from django import forms
+from django.core.exceptions import ValidationError
 from django.utils.translation import ugettext_lazy as _
 
 from plinth.modules import coturn
+from plinth.modules.coturn.components import TurnConfiguration
 
 
 def get_domain_choices():
@@ -14,6 +16,12 @@ def get_domain_choices():
     return ((domain, domain) for domain in coturn.get_available_domains())
 
 
+def turn_uris_validator(turn_uris):
+    """Validate list of STUN/TURN Server URIs."""
+    if not TurnConfiguration.validate_turn_uris(turn_uris.split("\n")):
+        raise ValidationError(_('Invalid list of STUN/TURN Server URIs'))
+
+
 class CoturnForm(forms.Form):
     """Form to select a TLS domain for Coturn."""
 

plinth/modules/ejabberd/forms.py

@@ -8,6 +8,7 @@ from django.urls import reverse_lazy
 from django.utils.translation import ugettext_lazy as _
 
 from plinth import cfg
+from plinth.modules.coturn.forms import turn_uris_validator
 from plinth.utils import format_lazy
 
 
@@ -35,7 +36,7 @@ class EjabberdForm(forms.Form):
         label=_('STUN/TURN Server URIs'), required=False, strip=True,
         widget=forms.Textarea(attrs={'rows': 4}),
         help_text=_('List of public URIs of the STUN/TURN server, one on each '
-                    'line.'))
+                    'line.'), validators=[turn_uris_validator])
 
     shared_secret = forms.CharField(
         label=_('Shared Authentication Secret'), required=False, strip=True,

plinth/modules/matrixsynapse/forms.py

@@ -5,8 +5,9 @@ Forms for the Matrix Synapse module.
 
 from django import forms
 from django.urls import reverse_lazy
-from django.utils.translation import ugettext_lazy as _
 
+from plinth.modules.coturn.forms import turn_uris_validator
+from django.utils.translation import ugettext_lazy as _
 from plinth.utils import format_lazy
 
 
@@ -30,7 +31,7 @@ class MatrixSynapseForm(forms.Form):
         label=_('STUN/TURN Server URIs'), required=False, strip=True,
         widget=forms.Textarea(attrs={'rows': 4}),
         help_text=_('List of public URIs of the STUN/TURN server, one on each '
-                    'line.'))
+                    'line.'), validators=[turn_uris_validator])
 
     shared_secret = forms.CharField(
         label=_('Shared Authentication Secret'), required=False, strip=True,