pbr: T6430: Allow forwarding into VRFs by name as well as route table IDs

* PBR can only target table IDs up to 200 and the previous PR to extend the
  range was rejected
* PBR with this PR can now also target VRFs directly by name, working around
  targeting problems for VRF table IDs outside the overlapping 100-200 range
* Validation ensures rules can't target both a table ID and a VRF name
  (internally they are handled the same)
* Added a simple accessor (get_vrf_table_id) for runtime mapping a VRF name
  to table ID, based on vyos.ifconfig.interface._set_vrf_ct_zone().
  It does not replace that usage, as it deliberately does not handle non-VRF
  interface lookups (would fail with a KeyError).
* Added route table ID lookup dict, global route table and VRF table defs
  to vyos.defaults. Table ID references have been updated in code touched
  by this PR.
* Added a simple smoketest to validate 'set vrf' usage in PBR rules

1 files changed, 10 insertions, 0 deletions

diff --git a/python/vyos/defaults.py b/python/vyos/defaults.py
index 9ccd925ce..25ee45391 100644
--- a/python/vyos/defaults.py
+++ b/python/vyos/defaults.py
@@ -50,3 +50,13 @@ commit_lock = os.path.join(directories['vyos_configdir'], '.lock')
 component_version_json = os.path.join(directories['data'], 'component-versions.json')
 
 config_default = os.path.join(directories['data'], 'config.boot.default')
+
+rt_symbolic_names = {
+  # Standard routing tables for Linux & reserved IDs for VyOS
+  'default': 253, # Confusingly, a final fallthru, not the default. 
+  'main': 254,    # The actual global table used by iproute2 unless told otherwise. 
+  'local': 255,   # Special kernel loopback table.
+}
+
+rt_global_vrf = rt_symbolic_names['main']
+rt_global_table = rt_symbolic_names['main']