[openwrt] Allow configure DNS resolvers without the need of defining

netjsonconfig/backends/openwrt/converters/__init__.py

@@ -1,5 +1,7 @@
 from .default import Default
 from .interfaces import Interfaces
+from .interfaces import DnsServer
+from .interfaces import DnsSearch
 from .general import General
 from .led import Led
 from .ntp import Ntp
@@ -10,7 +12,7 @@
 from .switch import Switch
 from .wireless import Wireless
 
-__all__ = ['Default', 'Interfaces', 'General',
+__all__ = ['Default', 'Interfaces', 'DnsServer', 'DnsSearch', 'General',
            'Led', 'Ntp', 'OpenVpn', 'Radios',
            'Routes', 'Rules', 'Switch',
            'Wireless']

netjsonconfig/backends/openwrt/converters/interfaces.py

@@ -311,3 +311,66 @@ def __netjson_dns(self, interface, result):
                 items = items.split()
             result.setdefault(netjson_key, [])
             result[netjson_key] += items
+
+
+class DnsServer(OpenWrtConverter):
+    netjson_key = 'dns_servers'
+    intermediate_key = 'network'
+    _uci_types = ['dns']
+
+    def to_intermediate_loop(self, block, result, index=None):
+        """
+        Convert dns_servers NetJson to intermediate data structure if
+        no interface was provided.
+        """
+        if 'interfaces' not in self.backend.config:
+            if index > 1:
+                result['network'][0]['dns'] += ' ' + block
+                return result
+            options = {
+                '.type': 'dns',
+                '.name': 'dns',
+                'dns': block
+            }
+            result.setdefault('network', [])
+            result['network'].append(self.sorted_dict(options))
+            return result
+
+    def to_netjson_loop(self, block, result, index=None):
+        if 'dns' in block:
+            items = block.pop('dns')
+            if isinstance(items, six.string_types):
+                items = items.split()
+            result.setdefault('dns_servers', [])
+            result['dns_servers'] += items
+        if 'dns_search' in block:
+            items = block.pop('dns_search')
+            if isinstance(items, six.string_types):
+                items = items.split()
+            result.setdefault('dns_search', [])
+            result['dns_search'] += items
+        return result
+
+
+class DnsSearch(OpenWrtConverter):
+    netjson_key = 'dns_search'
+    intermediate_key = 'network'
+    _uci_types = ['dns']
+
+    def to_intermediate_loop(self, block, result, index=None):
+        """
+        Convert dns_search NetJson to intermediate data structure if
+        no interface was provided.
+        """
+        if 'interfaces' not in self.backend.config:
+            if index > 1:
+                result['network'][0]['dns_search'] += ' ' + block
+                return result
+            options = {
+                '.type': 'dns',
+                '.name': 'dns',
+                'dns_search': block
+            }
+            result.setdefault('network', [])
+            result['network'].append(self.sorted_dict(options))
+            return result

netjsonconfig/backends/openwrt/openwrt.py

@@ -15,6 +15,8 @@ class OpenWrt(BaseBackend):
         converters.Ntp,
         converters.Led,
         converters.Interfaces,
+        converters.DnsServer,
+        converters.DnsSearch,
         converters.Routes,
         converters.Rules,
         converters.Switch,

tests/openwrt/test_interfaces.py

@@ -1027,6 +1027,33 @@ def test_parse_dns_list(self):
         o = OpenWrt(native=native)
         self.assertEqual(o.config, self._dns_netjson)
 
+    def test_render_dns_without_interface(self):
+        o = OpenWrt({
+            "dns_servers": ["10.11.12.13", "8.8.8.8"],
+            "dns_search": ["netjson.org", "openwisp.org"],
+        })
+        expected = self._tabs("""package network
+
+config dns 'dns'
+    option dns '10.11.12.13 8.8.8.8'
+    option dns_search 'netjson.org openwisp.org'
+""")
+        self.assertEqual(o.render(), expected)
+
+    def test_parse_dns_without_interface(self):
+        native = self._tabs("""package network
+
+config dns 'dns'
+    option dns '8.8.8.8 4.4.4.4'
+    option dns_search 'netjson.org openwisp.org'
+""")
+        _dns_json = {
+            "dns_servers": ["8.8.8.8", "4.4.4.4"],
+            "dns_search": ["netjson.org", "openwisp.org"],
+        }
+        o = OpenWrt(native=native)
+        self.assertEqual(o.config, _dns_json)
+
     def test_dns_dhcpv4_ignored(self):
         o = OpenWrt({
             "interfaces": [