T959: XML/Python rewrite of "protocol igmp-proxy" and op-mode commands

Examples:
=========

CFG commands:

  vyos@vyos# set protocols igmp-proxy disable-quickleave
  vyos@vyos# set protocols igmp-proxy interface eth0 alt-subnet '172.16.35.0/24'
  vyos@vyos# set protocols igmp-proxy interface eth0 alt-subnet '172.31.0.0/24'
  vyos@vyos# set protocols igmp-proxy interface eth0 role 'upstream'
  vyos@vyos# set protocols igmp-proxy interface eth1 role 'downstream'

  vyos@vyos# show protocols
   igmp-proxy {
       disable-quickleave
       interface eth0 {
           alt-subnet 172.16.35.0/24
           alt-subnet 172.31.0.0/24
           role upstream
       }
       interface eth1 {
           role downstream
       }
   }

OP mode commands:
-----------------

  vyos@vyos:~$ show ip multicast interface
   Interface  BytesIn      PktsIn       BytesOut     PktsOut      Local
   eth0       0.0b         0            0.0b         0            xxx.xxx.xxx.65
   eth1       0.0b         0            0.0b         0            xxx.xxx.xx.201

  vyos@vyos:~$ show ip multicast mfc
  Group           Origin          Pkts         Bytes        Wrong   In      Out
  xxx.x.xx.1      xxx.xx.0.1      10           9.81KB       0       eth0    eth1
  xxx.x.xx.2      xxx.xx.0.1                                        --

1 files changed, 179 insertions, 0 deletions

diff --git a/src/conf_mode/igmp_proxy.py b/src/conf_mode/igmp_proxy.py
new file mode 100755
index 000000000..b994369af
--- /dev/null
+++ b/src/conf_mode/igmp_proxy.py
@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+#
+
+import sys
+import os
+import jinja2
+
+from vyos.config import Config
+from vyos import ConfigError
+
+config_file = r'/etc/igmpproxy.conf'
+
+# Please be careful if you edit the template.
+config_tmpl = """
+########################################################
+#
+# autogenerated by igmp_proxy.py
+#
+#   The configuration file must define one upstream
+#   interface, and one or more downstream interfaces.
+#
+#   If multicast traffic originates outside the
+#   upstream subnet, the "altnet" option can be
+#   used in order to define legal multicast sources.
+#   (Se example...)
+#
+#   The "quickleave" should be used to avoid saturation
+#   of the upstream link. The option should only
+#   be used if it's absolutely nessecary to
+#   accurately imitate just one Client.
+#
+########################################################
+
+{% if not disable_quickleave -%}
+quickleave
+{% endif -%}
+
+{% for i in interface %}
+# Configuration for {{ i.interface }} ({{ i.role }} interface)
+{% if i.role == 'disabled' -%}
+phyint {{ i.interface }} disabled
+{%- else -%}
+phyint {{ i.interface }} {{ i.role }} ratelimit 0 threshold {{ i.threshold }}
+{%- endif -%}
+{%- for subnet in i.alt_subnet %}
+        altnet {{ subnet }}
+{%- endfor %}
+{%- for subnet in i.whitelist %}
+        whitelist {{ subnet }}
+{%- endfor %}
+{% endfor %}
+"""
+
+default_config_data = {
+    'disable': False,
+    'disable_quickleave': False,
+    'interface': [],
+}
+
+def get_config():
+    igmp_proxy = default_config_data
+    conf = Config()
+    if not conf.exists('protocols igmp-proxy'):
+        return None
+    else:
+        conf.set_level('protocols igmp-proxy')
+
+    # Network interfaces to listen on
+    if conf.exists('disable'):
+        igmp_proxy['disable'] = True
+
+    # Option to disable "quickleave"
+    if conf.exists('disable-quickleave'):
+        igmp_proxy['disable_quickleave'] = True
+
+    for intf in conf.list_nodes('interface'):
+        conf.set_level('protocols igmp-proxy interface {0}'.format(intf))
+        interface = {
+            'interface': intf,
+            'alt_subnet': [],
+            'role': 'downstream',
+            'threshold': '1',
+            'whitelist': []
+        }
+
+        if conf.exists('alt-subnet'):
+            interface['alt_subnet'] = conf.return_values('alt-subnet')
+
+        if conf.exists('role'):
+            interface['role'] = conf.return_value('role')
+
+        if conf.exists('threshold'):
+            interface['threshold'] = conf.return_value('threshold')
+
+        if conf.exists('whitelist'):
+            interface['whitelist'] = conf.return_values('whitelist')
+
+        # Append interface configuration to global configuration list
+        igmp_proxy['interface'].append(interface)
+
+    return igmp_proxy
+
+def verify(igmp_proxy):
+    # bail out early - looks like removal from running config
+    if igmp_proxy is None:
+        return None
+
+    # bail out early - service is disabled
+    if igmp_proxy['disable']:
+        return None
+
+    # at least two interfaces are required, one upstream and one downstream
+    if len(igmp_proxy['interface']) < 2:
+        raise ConfigError('Must define an upstream and at least 1 downstream interface!')
+
+    upstream = 0
+    for i in igmp_proxy['interface']:
+        if "upstream" == i['role']:
+            upstream += 1
+
+    if upstream == 0:
+        raise ConfigError('At least 1 upstream interface is required!')
+    elif upstream > 1:
+        raise ConfigError('Only 1 upstream interface allowed!')
+
+    return None
+
+def generate(igmp_proxy):
+    # bail out early - looks like removal from running config
+    if igmp_proxy is None:
+        return None
+
+    # bail out early - service is disabled, but inform user
+    if igmp_proxy['disable']:
+        print('Warning: IGMP Proxy will be deactivated because it is disabled')
+        return None
+
+    tmpl = jinja2.Template(config_tmpl)
+    config_text = tmpl.render(igmp_proxy)
+    with open(config_file, 'w') as f:
+        f.write(config_text)
+
+    return None
+
+def apply(igmp_proxy):
+    if igmp_proxy is None or igmp_proxy['disable']:
+         # IGMP Proxy support is removed in the commit
+         os.system('sudo systemctl stop igmpproxy.service')
+         if os.path.exists(config_file):
+             os.unlink(config_file)
+    else:
+        os.system('sudo systemctl restart igmpproxy.service')
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        sys.exit(1)