bfd: T5967: add minimum-ttl option

* set protocols bfd peer <x.x.x.x> minimum-ttl <1-254>
* set protocols bfd profile <name> minimum-ttl <1-254>

(cherry picked from commit 1f07dcbddfcfdbb9079936ec479c5633934dd547)

4 files changed, 31 insertions, 0 deletions

diff --git a/data/templates/frr/bfdd.frr.j2 b/data/templates/frr/bfdd.frr.j2
index c4adeb402..f3303e401 100644
--- a/data/templates/frr/bfdd.frr.j2
+++ b/data/templates/frr/bfdd.frr.j2
@@ -13,6 +13,9 @@ bfd
 {%             if profile_config.echo_mode is vyos_defined %}
   echo-mode
 {%             endif %}
+{%             if profile_config.minimum_ttl is vyos_defined %}
+  minimum-ttl {{ profile_config.minimum_ttl }}
+{%             endif %}
 {%             if profile_config.passive is vyos_defined %}
   passive-mode
 {%             endif %}
@@ -38,6 +41,9 @@ bfd
 {%             if peer_config.echo_mode is vyos_defined %}
   echo-mode
 {%             endif %}
+{%             if peer_config.minimum_ttl is vyos_defined %}
+  minimum-ttl {{ peer_config.minimum_ttl }}
+{%             endif %}
 {%             if peer_config.passive is vyos_defined %}
   passive-mode
 {%             endif %}
diff --git a/interface-definitions/include/bfd/common.xml.i b/interface-definitions/include/bfd/common.xml.i
index 126ab9b9a..8e6999d28 100644
--- a/interface-definitions/include/bfd/common.xml.i
+++ b/interface-definitions/include/bfd/common.xml.i
@@ -63,6 +63,18 @@
     </leafNode>
   </children>
 </node>
+<leafNode name="minimum-ttl">
+  <properties>
+    <help>Expect packets with at least this TTL</help>
+    <valueHelp>
+      <format>u32:1-254</format>
+      <description>Minimum TTL expected</description>
+    </valueHelp>
+    <constraint>
+      <validator name="numeric" argument="--range 1-254"/>
+    </constraint>
+  </properties>
+</leafNode>
 <leafNode name="passive">
   <properties>
     <help>Do not attempt to start sessions</help>
diff --git a/smoketest/scripts/cli/test_protocols_bfd.py b/smoketest/scripts/cli/test_protocols_bfd.py
index f209eae3a..716d0a806 100755
--- a/smoketest/scripts/cli/test_protocols_bfd.py
+++ b/smoketest/scripts/cli/test_protocols_bfd.py
@@ -32,6 +32,7 @@ peers = {
         'multihop'   : '',
         'source_addr': '192.0.2.254',
         'profile'    : 'foo-bar-baz',
+        'minimum_ttl': '20',
     },
     '192.0.2.20' : {
         'echo_mode'  : '',
@@ -63,6 +64,7 @@ profiles = {
         'intv_rx'    : '222',
         'intv_tx'    : '333',
         'shutdown'   : '',
+        'minimum_ttl': '40',
         },
     'foo-bar-baz' : {
         'intv_mult'  : '4',
@@ -109,6 +111,8 @@ class TestProtocolsBFD(VyOSUnitTestSHIM.TestCase):
                 self.cli_set(base_path + ['peer', peer, 'interval', 'receive', peer_config["intv_rx"]])
             if 'intv_tx' in peer_config:
                 self.cli_set(base_path + ['peer', peer, 'interval', 'transmit', peer_config["intv_tx"]])
+            if 'minimum_ttl' in peer_config:
+                self.cli_set(base_path + ['peer', peer, 'minimum-ttl', peer_config["minimum_ttl"]])
             if 'multihop' in peer_config:
                 self.cli_set(base_path + ['peer', peer, 'multihop'])
             if 'passive' in peer_config:
@@ -152,6 +156,8 @@ class TestProtocolsBFD(VyOSUnitTestSHIM.TestCase):
                 self.assertIn(f'receive-interval {peer_config["intv_rx"]}', peerconfig)
             if 'intv_tx' in peer_config:
                 self.assertIn(f'transmit-interval {peer_config["intv_tx"]}', peerconfig)
+            if 'minimum_ttl' in peer_config:
+                self.assertIn(f'minimum-ttl {peer_config["minimum_ttl"]}', peerconfig)
             if 'passive' in peer_config:
                 self.assertIn(f'passive-mode', peerconfig)
             if 'shutdown' in peer_config:
@@ -173,6 +179,8 @@ class TestProtocolsBFD(VyOSUnitTestSHIM.TestCase):
                 self.cli_set(base_path + ['profile', profile, 'interval', 'receive', profile_config["intv_rx"]])
             if 'intv_tx' in profile_config:
                 self.cli_set(base_path + ['profile', profile, 'interval', 'transmit', profile_config["intv_tx"]])
+            if 'minimum_ttl' in profile_config:
+                self.cli_set(base_path + ['profile', profile, 'minimum-ttl', profile_config["minimum_ttl"]])
             if 'passive' in profile_config:
                 self.cli_set(base_path + ['profile', profile, 'passive'])
             if 'shutdown' in profile_config:
@@ -210,6 +218,8 @@ class TestProtocolsBFD(VyOSUnitTestSHIM.TestCase):
                 self.assertIn(f' receive-interval {profile_config["intv_rx"]}', config)
             if 'intv_tx' in profile_config:
                 self.assertIn(f' transmit-interval {profile_config["intv_tx"]}', config)
+            if 'minimum_ttl' in profile_config:
+                self.assertIn(f' minimum-ttl {profile_config["minimum_ttl"]}', config)
             if 'passive' in profile_config:
                 self.assertIn(f' passive-mode', config)
             if 'shutdown' in profile_config:
diff --git a/src/conf_mode/protocols_bfd.py b/src/conf_mode/protocols_bfd.py
index dab784662..37421efb4 100755
--- a/src/conf_mode/protocols_bfd.py
+++ b/src/conf_mode/protocols_bfd.py
@@ -72,6 +72,9 @@ def verify(bfd):
                 if 'source' in peer_config and 'interface' in peer_config['source']:
                     raise ConfigError('BFD multihop and source interface cannot be used together')
 
+            if 'minimum_ttl' in peer_config and 'multihop' not in peer_config:
+                raise ConfigError('Minimum TTL is only available for multihop BFD sessions!')
+
             if 'profile' in peer_config:
                 profile_name = peer_config['profile']
                 if 'profile' not in bfd or profile_name not in bfd['profile']: