From 7d9bdfa31b85978dc30b099229d888c5e0804202 Mon Sep 17 00:00:00 2001
From: Abdul Karim <Abdul.Karim@morganstanley.com>
Date: Sat, 17 Feb 2024 18:48:18 +0000
Subject: [PATCH] ncm-network: nmstate - default gateway fix.

nmstate requires next-hop-interface for every route to be added.
Create default route entry only on the interface if default_gateway falls within subnet boundary.

fixes #1655
---
 ncm-network/src/main/perl/nmstate.pm          | 21 ++++++++++++++-----
 ncm-network/src/test/perl/nmstate_advance.t   | 12 +++++++++++
 ncm-network/src/test/perl/nmstate_simple.t    |  3 +++
 .../src/test/resources/nmstate_advance.pan    |  1 +
 4 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/ncm-network/src/main/perl/nmstate.pm b/ncm-network/src/main/perl/nmstate.pm
index e13f3a1388..18f67052b2 100644
--- a/ncm-network/src/main/perl/nmstate.pm
+++ b/ncm-network/src/main/perl/nmstate.pm
@@ -320,6 +320,13 @@ sub find_vlan_id {
     }
     return $vlanid;
 }
+# Check if given ip belongs to a network
+sub ip_in_network {
+    my ($self, $check_ip, $ip, $netmask) = @_;
+    # is the given ip in his ip/netmask.
+    my $subnet = NetAddr::IP->new("$ip", "$netmask");
+    return NetAddr::IP->new("$check_ip")->within($subnet);
+}
 
 # generates the hashrefs for interface in yaml file format needed by nmstate.
 # bulk of the config settings needed by the nmstate yml is done here.
@@ -414,12 +421,16 @@ sub generate_nmstate_config
     # create default route entry.
     my %default_rt;
     if ($default_gw) {
-        # create only default gw entry if gw entry match interface gateway defined
+        # create default gw entry on this interface only if it falls within the subnet boundary.
         # otherwise this interface is not the default gw interface.
-        if ((defined($iface->{gateway})) and ($iface->{gateway} eq $default_gw)) {
-            $default_rt{destination} = '0.0.0.0/0';
-            $default_rt{'next-hop-address'} = $default_gw;
-            $default_rt{'next-hop-interface'} = $device;
+        # next-hop-interface is mandatory in nmstate therefore we need interface to create default route entry.
+        if ((defined($iface->{ip})) and (defined($iface->{netmask}))) {
+            my $is_dgw_iface = $self->ip_in_network($default_gw, $iface->{ip}, $iface->{netmask});
+            if ($is_dgw_iface) {
+                $default_rt{destination} = '0.0.0.0/0';
+                $default_rt{'next-hop-address'} = $default_gw;
+                $default_rt{'next-hop-interface'} = $device;
+            }
         }
     }
     # combined default route with any policy routing/rule, if any
diff --git a/ncm-network/src/test/perl/nmstate_advance.t b/ncm-network/src/test/perl/nmstate_advance.t
index e4dc8a6e6a..af1eddcfd2 100644
--- a/ncm-network/src/test/perl/nmstate_advance.t
+++ b/ncm-network/src/test/perl/nmstate_advance.t
@@ -45,6 +45,9 @@ routes:
   config:
   - next-hop-interface: eth0
     state: absent
+  - destination: 0.0.0.0/0
+    next-hop-address: 4.3.2.254
+    next-hop-interface: eth0
   - destination: 1.2.3.4/32
     next-hop-interface: eth0
   - destination: 1.2.3.5/24
@@ -82,6 +85,9 @@ routes:
   config:
   - next-hop-interface: eth0.123
     state: absent
+  - destination: 0.0.0.0/0
+    next-hop-address: 4.3.2.254
+    next-hop-interface: eth0.123
   - destination: 1.2.3.4/32
     next-hop-interface: eth0.123
 EOF
@@ -107,6 +113,9 @@ routes:
   config:
   - next-hop-interface: vlan0
     state: absent
+  - destination: 0.0.0.0/0
+    next-hop-address: 4.3.2.254
+    next-hop-interface: eth0.123
   - destination: 1.2.3.4/32
     next-hop-interface: vlan0
 EOF
@@ -152,6 +161,9 @@ routes:
   config:
   - next-hop-interface: bond0
     state: absent
+  - destination: 0.0.0.0/0
+    next-hop-address: 4.3.2.254
+    next-hop-interface: bond0
 EOF
 
 
diff --git a/ncm-network/src/test/perl/nmstate_simple.t b/ncm-network/src/test/perl/nmstate_simple.t
index e313938c4c..5ca004519c 100644
--- a/ncm-network/src/test/perl/nmstate_simple.t
+++ b/ncm-network/src/test/perl/nmstate_simple.t
@@ -61,6 +61,9 @@ routes:
   config:
   - next-hop-interface: eth0
     state: absent
+  - destination: 0.0.0.0/0
+    next-hop-address: 4.3.2.254
+    next-hop-interface: eth0
 EOF
 
 Readonly my $NOTTOREMOVE => <<EOF;
diff --git a/ncm-network/src/test/resources/nmstate_advance.pan b/ncm-network/src/test/resources/nmstate_advance.pan
index 51c292963d..1896c6eecb 100644
--- a/ncm-network/src/test/resources/nmstate_advance.pan
+++ b/ncm-network/src/test/resources/nmstate_advance.pan
@@ -3,6 +3,7 @@ object template nmstate_advance;
 include 'simple_base_profile';
 include 'components/network/config-nmstate';
 
+"/system/network/default_gateway" = "4.3.2.254";
 # additional interface testing for nmstate.
 "/system/network/interfaces/eth1" = create("dhcpinterface");
 "/hardware/cards/nic/eth1/hwaddr" = "6e:a5:1b:55:77:0b";