sd-dhcp-client/networkd: add domainname support

src/network/networkd-gperf.gperf

@@ -33,5 +33,6 @@ Route.Destination,       config_parse_destination,      0,       0
 DHCPv4.UseDNS,           config_parse_bool,             0,       offsetof(Network, dhcp_dns)
 DHCPv4.UseMTU,           config_parse_bool,             0,       offsetof(Network, dhcp_mtu)
 DHCPv4.UseHostname,      config_parse_bool,             0,       offsetof(Network, dhcp_hostname)
+DHCPv4.UseDomainName,    config_parse_bool,             0,       offsetof(Network, dhcp_domainname)
 Bridge.Description,      config_parse_string,           0,       offsetof(Bridge, description)
 Bridge.Name,             config_parse_ifname,           0,       offsetof(Bridge, name)

src/network/networkd-manager.c

@@ -325,6 +325,7 @@ int manager_update_resolv_conf(Manager *m) {
         Link *link;
         Iterator i;
         unsigned count = 0;
+        const char *domainname = NULL;
         int r;
 
         assert(m);
@@ -350,12 +351,20 @@ int manager_update_resolv_conf(Manager *m) {
                         struct in_addr *nameservers;
                         size_t nameservers_size;
 
-                        r = sd_dhcp_client_get_dns(link->dhcp, &nameservers, &nameservers_size);
-                        if (r >= 0) {
-                                unsigned j;
+                        if (link->network->dhcp_dns) {
+                                r = sd_dhcp_client_get_dns(link->dhcp, &nameservers, &nameservers_size);
+                                if (r >= 0) {
+                                        unsigned j;
 
-                                for (j = 0; j < nameservers_size; j++)
-                                        append_dns(f, &nameservers[j], AF_INET, &count);
+                                        for (j = 0; j < nameservers_size; j++)
+                                                append_dns(f, &nameservers[j], AF_INET, &count);
+                                }
+                        }
+
+                        if (link->network->dhcp_domainname && !domainname) {
+                                r = sd_dhcp_client_get_domainname(link->dhcp, &domainname);
+                                if (r >= 0)
+                                       fprintf(f, "domain %s\n", domainname);
                         }
                 }
         }

src/network/networkd-network.c

@@ -68,6 +68,7 @@ static int network_load_one(Manager *manager, const char *filename) {
         network->dhcp_dns = true;
         network->dhcp_mtu = true;
         network->dhcp_hostname = true;
+        network->dhcp_domainname = true;
 
         r = config_parse(NULL, filename, file, "Match\0Network\0Address\0Route\0DHCPv4\0", config_item_perf_lookup,
                         (void*) network_gperf_lookup, false, false, network);

src/network/networkd.h

@@ -89,6 +89,7 @@ struct Network {
         bool dhcp_dns;
         bool dhcp_mtu;
         bool dhcp_hostname;
+        bool dhcp_domainname;
 
         LIST_HEAD(Address, static_addresses);
         LIST_HEAD(Route, static_routes);