Merge pull request #29544 from yuwata/network-dhcp-bus-command

network: several fixlets for DBus methods for DHCP client and server

src/libsystemd-network/sd-dhcp-server.c

@@ -113,7 +113,8 @@ int sd_dhcp_server_configure_pool(
 }
 
 int sd_dhcp_server_is_running(sd_dhcp_server *server) {
-        assert_return(server, false);
+        if (!server)
+                return false;
 
         return !!server->receive_message;
 }

src/network/networkd-link-bus.c

@@ -599,7 +599,7 @@ int bus_link_method_force_renew(sd_bus_message *message, void *userdata, sd_bus_
         if (r == 0)
                 return 1; /* Polkit will call us back */
 
-        if (l->dhcp_server) {
+        if (sd_dhcp_server_is_running(l->dhcp_server)) {
                 r = sd_dhcp_server_forcerenew(l->dhcp_server);
                 if (r < 0)
                         return r;
@@ -626,11 +626,15 @@ int bus_link_method_renew(sd_bus_message *message, void *userdata, sd_bus_error
         if (r == 0)
                 return 1; /* Polkit will call us back */
 
-        if (l->dhcp_client) {
+        if (sd_dhcp_client_is_running(l->dhcp_client))
                 r = sd_dhcp_client_send_renew(l->dhcp_client);
-                if (r < 0)
-                        return r;
-        }
+        else
+                /* The DHCPv4 client may have been stopped by the IPv6 only mode. Let's unconditionally
+                 * restart the client here. Note, if the DHCPv4 client is disabled, then dhcp4_start() does
+                 * nothing and returns 0. */
+                r = dhcp4_start(l);
+        if (r < 0)
+                return r;
 
         return sd_bus_reply_method_return(message, NULL);
 }