new ifupdown2 link module to create dummy devices

Ticket: CM-3525
Reviewed By: CCR-3326
Testing Done: Tested creating dummy devices using ifupdown2

This is modification to gospos loopback module. It solves the same
purpose ie using linux dummy device like a loopback device but there were
objections on calling it loopback so i have renamed it to link and i have changed it
into a generic module that can do any 'ip link'. Can be extended for
link args in the future.

below example creates a loopy device

$ifquery loopy
auto loopy
iface loopy
link-type dummy

$ifup loopy
$ifquery -c loopy
auto loopy
iface loopy [pass]
link-type dummy [pass]

(cherry picked from commit 1151420408a53c106d29183a1e0da5562c8b03a3)

addons/link.py

@@ -11,20 +11,25 @@ from ifupdownaddons.modulebase import moduleBase
 from ifupdownaddons.iproute2 import iproute2
 import logging
 
-class loopback(moduleBase):
-    _modinfo = {'mhelp' : 'configure extra loopback module based on ' +
-			  'dummy device' }
+class link(moduleBase):
+    _modinfo = {'mhelp' : 'create/configure link types. similar to ip-link',
+                'attrs' : {
+                   'link-type' :
+                        {'help' : 'type of link as in \'ip link\' command.',
+                         'example' : ['link-type <dummy|veth>']}}}
 
     def __init__(self, *args, **kargs):
         moduleBase.__init__(self, *args, **kargs)
         self.ipcmd = None
 
-    def _is_loopback_by_name(self, ifacename):
-        return 'loop' in ifacename
+    def _is_my_interface(self, ifaceobj):
+        if ifaceobj.get_attr_value_first('link-type'):
+            return True
+        return False
 
     def _up(self, ifaceobj):
-        if self._is_loopback_by_name(ifaceobj.name):
-           self.ipcmd.link_create(ifaceobj.name, 'dummy')
+        self.ipcmd.link_create(ifaceobj.name,
+                               ifaceobj.get_attr_value_first('link-type'))
 
     def _down(self, ifaceobj):
         if not self.PERFMODE and not self.ipcmd.link_exists(ifaceobj.name):
@@ -36,7 +41,15 @@ class loopback(moduleBase):
 
     def _query_check(self, ifaceobj, ifaceobjcurr):
         if not self.ipcmd.link_exists(ifaceobj.name):
-           return
+            ifaceobjcurr.update_config_with_status('link-type', 'None', 1)
+        else:
+            link_type = ifaceobj.get_attr_value_first('link-type')
+            if self.ipcmd.link_get_kind(ifaceobj.name) == link_type:
+                ifaceobjcurr.update_config_with_status('link-type',
+                                                        link_type, 0)
+            else:
+                ifaceobjcurr.update_config_with_status('link-type',
+                                                        link_type, 1)
 
     _run_ops = {'pre-up' : _up,
                'post-down' : _down,
@@ -54,7 +67,7 @@ class loopback(moduleBase):
         if not op_handler:
             return
         if (operation != 'query-running' and
-                not self._is_loopback_by_name(ifaceobj.name)):
+                not self._is_my_interface(ifaceobj)):
             return
         self._init_command_handlers()
         if operation == 'query-checkcurr':

config/addons.conf

@@ -1,4 +1,6 @@
+pre-up,link
 pre-up,bond
+pre-up,clagd
 pre-up,vlan
 pre-up,vxlan
 pre-up,clagd
@@ -29,3 +31,4 @@ post-down,vxlan
 post-down,vlan
 post-down,bond
 post-down,usercmds
+post-down,link

ifupdownaddons/iproute2.py

@@ -67,7 +67,11 @@ class iproute2(utilsBase):
                 elif citems[i] == 'link/ether': linkattrs['hwaddress'] = citems[i+1]
                 elif citems[i] == 'vlan' and citems[i+1] == 'id':
                     linkattrs['linkinfo'] = {'vlanid' : citems[i+2]}
+                    linkattrs['kind'] = 'vlan'
+                elif citems[i] == 'dummy':
+                    linkattrs['kind'] = 'dummy'
                 elif citems[i] == 'vxlan' and citems[i+1] == 'id':
+                    linkattrs['kind'] = 'vxlan'
                     vattrs = {'vxlanid' : citems[i+2],
                               'svcnode' : [],
                               'remote'  : [],
@@ -568,6 +572,9 @@ class iproute2(utilsBase):
     def link_get_mtu(self, ifacename):
         return self._cache_get('link', [ifacename, 'mtu'])
 
+    def link_get_kind(self, ifacename):
+        return self._cache_get('link', [ifacename, 'kind'])
+
     def link_get_hwaddress(self, ifacename):
         address = self._cache_get('link', [ifacename, 'hwaddress'])
         # newly created logical interface addresses dont end up in the cache

setup.py

@@ -37,8 +37,9 @@ setup(name='ifupdown2',
                       'addons/bond.py', 'addons/vlan.py',
                       'addons/mstpctl.py', 'addons/address.py',
                       'addons/dhcp.py', 'addons/usercmds.py',
-                      'addons/ethtool.py', 'addons/loopback.py',
+                      'addons/ethtool.py',
                       'addons/addressvirtual.py', 'addons/vxlan.py',
+                      'addons/link.py',
                       'addons/bridgevlan.py']),
                   ('/var/lib/ifupdownaddons/', ['config/addons.conf']),
                   ('/var/lib/ifupdownaddons/policy.d/', []),