dhcp-server: T9267: add client-class matching on hostname/vendor-class-id

Client classes could previously only match on relay agent information
(Option 82). Add matching on the client-sent hostname (Option 12) and
vendor class identifier (Option 60), each with an exact-value or
substring form, so clients sharing a subnet can be told apart by e.g.
device model without splitting the subnet into per-model pools.

Also let a client-class deliver its own options (reusing the existing
subnet/range option syntax), so a match can directly hand out a
model-specific value such as a provisioning URL, independent of which
pool the client's lease is drawn from.

2 files changed, 41 insertions, 4 deletions

diff --git a/python/vyos/kea.py b/python/vyos/kea.py
index 436c134c8..e42bb6e1c 100644
--- a/python/vyos/kea.py
+++ b/python/vyos/kea.py
@@ -725,11 +725,32 @@ def kea_get_server_leases(
     return data
 
 
-def _build_relay_hex_condition(sub_option_index, value):
+def _kea_hex_literal(value):
     if value.startswith('0x'):
-        return f'relay4[{sub_option_index}].hex == {value}'
-    else:
-        return f'relay4[{sub_option_index}].hex == 0x{value.encode().hex().lower()}'
+        return value
+    return f'0x{value.encode().hex().lower()}'
+
+
+def _build_hex_condition(kea_path, value):
+    return f'{kea_path}.hex == {_kea_hex_literal(value)}'
+
+
+def _build_relay_hex_condition(sub_option_index, value):
+    return _build_hex_condition(f'relay4[{sub_option_index}]', value)
+
+
+def _build_option_match_condition(option_number, match_config):
+    kea_path = f'option[{option_number}]'
+
+    if 'substring' in match_config:
+        substring_config = match_config['substring']
+        offset = substring_config.get('offset', '0')
+        value_hex = _kea_hex_literal(substring_config['value'])
+        # length is expressed in bytes; a hex literal is '0x' + 2 hex digits per byte
+        length = substring_config.get('length') or str((len(value_hex) - 2) // 2)
+        return f'substring({kea_path}.hex, {offset}, {length}) == {value_hex}'
+
+    return _build_hex_condition(kea_path, match_config['value'])
 
 
 def kea_build_client_class_test(config):
@@ -749,6 +770,12 @@ def kea_build_client_class_test(config):
                 )
             )
 
+    if 'hostname' in config:
+        conditions.append(_build_option_match_condition(12, config['hostname']))
+
+    if 'vendor_class_id' in config:
+        conditions.append(_build_option_match_condition(60, config['vendor_class_id']))
+
     test = ' and '.join(conditions)
 
     return test
diff --git a/python/vyos/template.py b/python/vyos/template.py
index 2c07d79da..6323657ed 100755
--- a/python/vyos/template.py
+++ b/python/vyos/template.py
@@ -982,6 +982,7 @@ def kea_high_availability_json(config):
 @register_filter('kea_client_class_json')
 def kea_client_class_json(client_classes):
     from vyos.kea import kea_build_client_class_test
+    from vyos.kea import kea_parse_options
     from json import dumps
     out = []
 
@@ -994,6 +995,15 @@ def kea_client_class_json(client_classes):
             'test': kea_build_client_class_test(config)
         }
 
+        if 'option' in config:
+            client_class['option-data'] = kea_parse_options(config['option'])
+
+            if 'bootfile_name' in config['option']:
+                client_class['boot-file-name'] = config['option']['bootfile_name']
+
+            if 'bootfile_server' in config['option']:
+                client_class['next-server'] = config['option']['bootfile_server']
+
         out.append(client_class)
 
     return dumps(out, indent=4)