[openwrt] Allow configure DNS resolvers without defining an interfaces …

…#117

Fixed the issue by defining two additional classes (DnsServer and
DnsSearch) in the interfaces
converter. These additional classes are to convert the dns configs when
an interface is not provided in the netjson. when an interface is provided, the default
converters in the Interface class is used to convert the dns to native
config. this was left so because when an interface is defined, other
options like DHCP servers might be available and the Interface class
handles that very well.
Test cases were added to test for these features and also to increase
the coverage.

Fixes #117

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": [