[change] Support for instantiating OpenWrt with both 21 and legacy mode #618

Closes #618

Co-authored-by: Gagan Deep <pandafy.dev@gmail.com>

Author: codesankalp

README.rst

@@ -730,6 +730,60 @@ reset to empty state to avoid potential conflicts.
 Set this to ``False`` if every organization has its dedicated management
 tunnel with a dedicated address space that is reachable by the OpenWISP server.
 
+``OPENWISP_CONTROLLER_DSA_OS_MAPPING``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
++--------------+----------+
+| **type**:    | ``dict`` |
++--------------+----------+
+| **default**: | ``{}``   |
++--------------+----------+
+
+OpenWISP Controller can figure out whether it should use the new OpenWrt syntax
+for DSA interfaces (Distributed Switch Architecture) introduced in OpenWrt 21 by
+reading the ``os`` field of the ``Device`` object. However, if the firmware you
+are using has a custom firmware identifier, the system will not be able to figure
+out whether it should use the new syntax and it will default to
+`OPENWISP_CONTROLLER_DSA_DEFAULT_FALLBACK <#openwisp_controller_dsa_default_fallback>`_.
+
+If you want to make sure the system can parse your custom firmware
+identifier properly, you can follow the example below.
+
+For the sake of the example, the OS identifier ``MyCustomFirmware 2.0``
+corresponds to ``OpenWrt 19.07``, while ``MyCustomFirmware 2.1`` corresponds to
+``OpenWrt 21.02``. Configuring this setting as indicated below will allow
+OpenWISP to supply the right syntax automatically.
+
+Example:
+
+.. code-block:: python
+
+    OPENWISP_CONTROLLER_DSA_OS_MAPPING = {
+        'netjsonconfig.OpenWrt': {
+            # OpenWrt >=21.02 configuration syntax will be used for
+            # these OS identifiers.
+            '>=21.02': [r'MyCustomFirmware 2.1(.*)'],
+            # OpenWrt <=21.02 configuration syntax will be used for
+            # these OS identifiers.
+            '<21.02': [r'MyCustomFirmware 2.0(.*)']
+        }
+    }
+
+**Note**: The OS identifier should be a regular expression as shown in above example.
+
+``OPENWISP_CONTROLLER_DSA_DEFAULT_FALLBACK``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
++--------------+----------+
+| **type**:    | ``bool`` |
++--------------+----------+
+| **default**: | ``True`` |
++--------------+----------+
+
+The value of this setting decides whether to use DSA syntax
+(OpenWrt >=21 configuration syntax) if openwisp-controller fails
+to make that decision automatically.
+
 REST API
 --------
 

openwisp_controller/config/base/base.py

@@ -141,13 +141,13 @@ def backend_instance(self):
         """
         return self.get_backend_instance()
 
-    def get_backend_instance(self, template_instances=None, context=None):
+    def get_backend_instance(self, template_instances=None, context=None, **kwargs):
         """
         allows overriding config and templates
         needed for pre validation of m2m
         """
         backend = self.backend_class
-        kwargs = {'config': self.get_config()}
+        kwargs.update({'config': self.get_config()})
         context = context or {}
         # determine if we can pass templates
         # expecting a many2many relationship

openwisp_controller/config/base/config.py

@@ -1,5 +1,6 @@
 import collections
 import logging
+import re
 
 from cache_memoize import cache_memoize
 from django.core.exceptions import ObjectDoesNotExist, PermissionDenied, ValidationError
@@ -8,6 +9,8 @@
 from jsonfield import JSONField
 from model_utils import Choices
 from model_utils.fields import StatusField
+from netjsonconfig import OpenWrt
+from packaging import version
 from swapper import get_model_name
 
 from .. import settings as app_settings
@@ -356,6 +359,47 @@ def get_default_templates(self):
             organization_id=org_id, queryset=queryset, backend=self.backend
         )
 
+    def _should_use_dsa(self):
+        if not hasattr(self, 'device') or not issubclass(self.backend_class, OpenWrt):
+            return
+
+        if not self.device.os:
+            # Device os field is empty. Early return to
+            # prevent unnecessary computation.
+            return app_settings.DSA_DEFAULT_FALLBACK
+
+        # Check if the device is using stock OpenWrt.
+        openwrt_match = re.search(
+            '[oO][pP][eE][nN][wW][rR][tT]\s*([\d.]+)', self.device.os
+        )
+        if openwrt_match:
+            if version.parse(openwrt_match.group(1)) >= version.parse('21'):
+                return True
+            else:
+                return False
+
+        # Device is using custom firmware
+        if app_settings.DSA_OS_MAPPING:
+            openwrt_based_firmware = app_settings.DSA_OS_MAPPING.get(
+                'netjsonconfig.OpenWrt', {}
+            )
+            dsa_enabled_os = openwrt_based_firmware.get('>=21.02', [])
+            dsa_disabled_os = openwrt_based_firmware.get('<21.02', [])
+            for os in dsa_enabled_os:
+                if re.search(os, self.device.os):
+                    return True
+            for os in dsa_disabled_os:
+                if re.search(os, self.device.os):
+                    return False
+
+        return app_settings.DSA_DEFAULT_FALLBACK
+
+    def get_backend_instance(self, template_instances=None, context=None, **kwargs):
+        dsa_enabled = self._should_use_dsa()
+        if dsa_enabled is not None:
+            kwargs['dsa'] = dsa_enabled
+        return super().get_backend_instance(template_instances, context, **kwargs)
+
     def clean(self):
         """
         * validates context field

openwisp_controller/config/settings.py

@@ -76,3 +76,5 @@ def get_settings_value(option, default):
 SHARED_MANAGEMENT_IP_ADDRESS_SPACE = get_settings_value(
     'SHARED_MANAGEMENT_IP_ADDRESS_SPACE', True
 )
+DSA_OS_MAPPING = get_settings_value('DSA_OS_MAPPING', {})
+DSA_DEFAULT_FALLBACK = get_settings_value('DSA_DEFAULT_FALLBACK', True)

openwisp_controller/config/tests/test_config.py

@@ -55,6 +55,58 @@ def test_backend_instance(self):
         c = Config(backend='netjsonconfig.OpenWrt', config=config)
         self.assertIsInstance(c.backend_instance, OpenWrt)
 
+    @patch.object(app_settings, 'DSA_DEFAULT_FALLBACK', False)
+    @patch.object(
+        app_settings,
+        'DSA_OS_MAPPING',
+        {
+            'netjsonconfig.OpenWrt': {
+                '>=21.02': [r'MyCustomFirmware 2.1(.*)'],
+                '<21.02': [r'MyCustomFirmware 2.0(.*)'],
+            }
+        },
+    )
+    def test_backend_openwrt_different_versions(self):
+        with self.subTest('DSA enabled OpenWrt firmware'):
+            c = Config(
+                backend='netjsonconfig.OpenWrt',
+                device=Device(name='test', os='OpenWrt 21.02.2 r16495-bf0c965af0'),
+            )
+            self.assertIsInstance(c.backend_instance, OpenWrt)
+            self.assertEqual(c.backend_instance.dsa, True)
+
+        with self.subTest('DSA disabed OpenWrt Firmware'):
+            c = Config(
+                backend='netjsonconfig.OpenWrt',
+                device=Device(name='test', os='OpenWrt 19.02.2 r16495-bf0c965af0'),
+            )
+            self.assertIsInstance(c.backend_instance, OpenWrt)
+            self.assertEqual(c.backend_instance.dsa, False)
+
+        with self.subTest('DSA enabled custom firmware'):
+            c = Config(
+                backend='netjsonconfig.OpenWrt',
+                device=Device(name='test', os='MyCustomFirmware 2.1.2'),
+            )
+            self.assertIsInstance(c.backend_instance, OpenWrt)
+            self.assertEqual(c.backend_instance.dsa, True)
+
+        with self.subTest('DSA disabled custom firmware'):
+            c = Config(
+                backend='netjsonconfig.OpenWrt',
+                device=Device(name='test', os='MyCustomFirmware 2.0.1'),
+            )
+            self.assertIsInstance(c.backend_instance, OpenWrt)
+            self.assertEqual(c.backend_instance.dsa, False)
+
+        with self.subTest('Device os field is empty'):
+            c = Config(
+                backend='netjsonconfig.OpenWrt',
+                device=Device(name='test', os=''),
+            )
+            self.assertIsInstance(c.backend_instance, OpenWrt)
+            self.assertEqual(c.backend_instance.dsa, False)
+
     def test_netjson_validation(self):
         config = {'interfaces': {'invalid': True}}
         c = Config(