util: T2241: add get_bridge_member_config function

Function that parses the config of a bridge member into a dict that is
needed to apply all port config when adding a port to a bridge.
Needed because other interfaces will be adding themselves to the bridge
outside of the bridge conf_mode script and they need a common place to
get their config.
Can't be put as method of BridgeIf as we can't invoke it without it
creating the bridge (create=False raises an exception), we need to
get the configuration before we create the interface.

1 files changed, 47 insertions, 0 deletions

diff --git a/python/vyos/util.py b/python/vyos/util.py
index c708c1eb4..e598e0ff3 100644
--- a/python/vyos/util.py
+++ b/python/vyos/util.py
@@ -522,3 +522,50 @@ def ifname_from_config(conf):
 
     # no vlans
     return level[-1]
+
+def get_bridge_member_config(conf, br, intf):
+    """
+    Gets bridge port (member) configuration
+
+    Arguments:
+    conf: Config
+    br: bridge name
+    intf: interface name
+
+    Returns:
+    dict with the configuration
+    False if bridge or bridge port doesn't exist
+    """
+    old_level = conf.get_level()
+    conf.set_level([])
+
+    bridge = f'interfaces bridge {br}'
+    member = f'{bridge} member interface {intf}'
+    if not ( conf.exists(bridge) and conf.exists(member) ):
+        return False
+
+    # default bridge port configuration
+    # cost and priority initialized with linux defaults
+    # by reading /sys/devices/virtual/net/br0/brif/eth2/{path_cost,priority}
+    # after adding interface to bridge after reboot
+    memberconf = {
+        'cost': 100,
+        'priority': 32,
+        'arp_cache_tmo': 30,
+        'disable_link_detect': 1,
+    }
+
+    if conf.exists(f'{member} cost'):
+        memberconf['cost'] = int(conf.return_value(f'{member} cost'))
+
+    if conf.exists(f'{member} priority'):
+        memberconf['priority'] = int(conf.return_value(f'{member} priority'))
+
+    if conf.exists(f'{bridge} ip arp-cache-timeout'):
+        memberconf['arp_cache_tmo'] = int(conf.return_value(f'{bridge} ip arp-cache-timeout'))
+
+    if conf.exists(f'{bridge} disable-link-detect'):
+        memberconf['disable_link_detect'] = 2
+
+    conf.set_level(old_level)
+    return memberconf