From 781d5e4163a78f0299b3efcaae3ac7aade9de76b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vin=C3=ADcius=20Ferr=C3=A3o?=
 <2031761+viniciusferrao@users.noreply.github.com>
Date: Fri, 31 Jul 2026 15:18:43 -0300
Subject: [PATCH] fix(dhcp): preserve Kea reservations on makedhcp -n

---
 perl-xCAT/xCAT/DHCP/Backend/Kea.pm   | 36 ++++++++++++++++++++++++++++
 xCAT-server/lib/xcat/plugins/dhcp.pm | 18 ++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/perl-xCAT/xCAT/DHCP/Backend/Kea.pm b/perl-xCAT/xCAT/DHCP/Backend/Kea.pm
index 2525ae7d3..30f6a028f 100644
--- a/perl-xCAT/xCAT/DHCP/Backend/Kea.pm
+++ b/perl-xCAT/xCAT/DHCP/Backend/Kea.pm
@@ -630,6 +630,42 @@ sub query_reservations {
     return \@found;
 }
 
+sub preserve_reservations {
+    my ( $self, $config, $intent ) = @_;
+
+    my $target_subnets = $intent->{subnets} || [];
+    return $intent unless @$target_subnets;
+
+    my $target_config = $config->{Dhcp6}
+      ? { Dhcp6 => { subnet6 => $target_subnets } }
+      : { Dhcp4 => { subnet4 => $target_subnets } };
+
+    foreach my $source_subnet ( _subnets_for_config($config) ) {
+        foreach my $reservation ( @{ $source_subnet->{reservations} || [] } ) {
+            my $ip = $reservation->{'ip-address'};
+            $ip = $reservation->{'ip-addresses'}[0]
+              if !$ip && ref( $reservation->{'ip-addresses'} ) eq 'ARRAY';
+
+            my $target_subnet;
+            if ($ip) {
+                my $subnet_id = $self->subnet_id_for_ip( $target_config, $ip );
+                $target_subnet = _find_subnet_by_id( $target_config, $subnet_id ) if defined($subnet_id);
+            }
+            if ( !$target_subnet && $source_subnet->{subnet} ) {
+                ($target_subnet) = grep {
+                    ( $_->{subnet} || '' ) eq $source_subnet->{subnet}
+                } @$target_subnets;
+            }
+            next unless $target_subnet;
+
+            $target_subnet->{reservations} ||= [];
+            push @{ $target_subnet->{reservations} }, { %$reservation };
+        }
+    }
+
+    return $intent;
+}
+
 sub subnet_id_for_ip {
     my ( $self, $config, $ip ) = @_;
 
diff --git a/xCAT-server/lib/xcat/plugins/dhcp.pm b/xCAT-server/lib/xcat/plugins/dhcp.pm
index 167b8cf20..29eee214c 100644
--- a/xCAT-server/lib/xcat/plugins/dhcp.pm
+++ b/xCAT-server/lib/xcat/plugins/dhcp.pm
@@ -2381,6 +2381,24 @@ sub kea_process_request
     }
 
     if ($opt->{n}) {
+        my $loaded4 = $backend->load_dhcp4_config();
+        if ($loaded4->{error}) {
+            $callback->({ error => [ $loaded4->{error} ], errorcode => [1] });
+            flock($dhcplockfd, LOCK_UN);
+            return;
+        }
+        $backend->preserve_reservations($loaded4, $intent4);
+
+        if ($using_dhcp6) {
+            my $loaded6 = $backend->load_dhcp6_config();
+            if ($loaded6->{error}) {
+                $callback->({ error => [ $loaded6->{error} ], errorcode => [1] });
+                flock($dhcplockfd, LOCK_UN);
+                return;
+            }
+            $backend->preserve_reservations($loaded6, $intent6);
+        }
+
         my $result = $backend->write_dhcp4_config($intent4, backup_existing => 1);
         if ($result->{error}) {
             $callback->({ error => [ $result->{error} ], errorcode => [1] });