ip: T4517: add option to enable directed broadcast forwarding

Directed broadcast is described in rfc1812#section-5.3.5.2 and rfc2644.

By default Linux kernel doesn't forward directed broadcast
packets unless both of `/proc/sys/net/ipv4/conf/all/bc_forwarding`
and `/proc/sys/net/ipv4/conf/$iface/bc_forwarding` are set to 1.

2 files changed, 16 insertions, 1 deletions

diff --git a/smoketest/scripts/cli/base_interfaces_test.py b/smoketest/scripts/cli/base_interfaces_test.py
index 8acf52243..55343b893 100644
--- a/smoketest/scripts/cli/base_interfaces_test.py
+++ b/smoketest/scripts/cli/base_interfaces_test.py
@@ -638,6 +638,7 @@ class BasicInterfaceTest:
                 self.cli_set(path + ['ip', 'arp-cache-timeout', arp_tmo])
                 self.cli_set(path + ['ip', 'disable-arp-filter'])
                 self.cli_set(path + ['ip', 'disable-forwarding'])
+                self.cli_set(path + ['ip', 'enable-directed-broadcast'])
                 self.cli_set(path + ['ip', 'enable-arp-accept'])
                 self.cli_set(path + ['ip', 'enable-arp-announce'])
                 self.cli_set(path + ['ip', 'enable-arp-ignore'])
@@ -674,6 +675,9 @@ class BasicInterfaceTest:
                 tmp = read_file(f'{proc_base}/forwarding')
                 self.assertEqual('0', tmp)
 
+                tmp = read_file(f'{proc_base}/bc_forwarding')
+                self.assertEqual('1', tmp)
+
                 tmp = read_file(f'{proc_base}/proxy_arp')
                 self.assertEqual('1', tmp)
 
diff --git a/smoketest/scripts/cli/test_system_ip.py b/smoketest/scripts/cli/test_system_ip.py
index 83df9d99e..00fce654c 100755
--- a/smoketest/scripts/cli/test_system_ip.py
+++ b/smoketest/scripts/cli/test_system_ip.py
@@ -28,7 +28,7 @@ class TestSystemIP(VyOSUnitTestSHIM.TestCase):
 
     def test_system_ip_forwarding(self):
         # Test if IPv4 forwarding can be disabled globally, default is '1'
-        # which means forwearding enabled
+        # which means forwarding enabled
         all_forwarding = '/proc/sys/net/ipv4/conf/all/forwarding'
         self.assertEqual(read_file(all_forwarding), '1')
 
@@ -37,6 +37,17 @@ class TestSystemIP(VyOSUnitTestSHIM.TestCase):
 
         self.assertEqual(read_file(all_forwarding), '0')
 
+    def test_system_ip_directed_broadcast_forwarding(self):
+        # Test if IPv4 directed broadcast forwarding can be disabled globally, default is '1'
+        # which means forwarding enabled
+        bc_forwarding = '/proc/sys/net/ipv4/conf/all/bc_forwarding'
+        self.assertEqual(read_file(bc_forwarding), '1')
+
+        self.cli_set(base_path + ['disable-directed-broadcast-forwarding'])
+        self.cli_commit()
+
+        self.assertEqual(read_file(bc_forwarding), '0')
+
     def test_system_ip_multipath(self):
         # Test IPv4 multipathing options, options default to off -> '0'
         use_neigh = '/proc/sys/net/ipv4/fib_multipath_use_neigh'