sd-network: Introduce API to access DHCP4 client ID

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

@@ -168,6 +168,10 @@ _public_ int sd_network_link_get_address_state(int ifindex, char **state) {
         return network_link_get_string(ifindex, "ADDRESS_STATE", state);
 }
 
+_public_ int sd_network_link_get_dhcp4_client_id_string(int ifindex, char **client_id) {
+        return network_link_get_string(ifindex, "DHCP4_CLIENT_ID", client_id);
+}
+
 _public_ int sd_network_link_get_required_for_online(int ifindex) {
         _cleanup_free_ char *s = NULL;
         int r;

src/systemd/sd-network.h

@@ -188,6 +188,9 @@ int sd_network_link_get_carrier_bound_by(int ifindex, int **ifindexes);
 /* Get the timezone that was learnt on a specific link. */
 int sd_network_link_get_timezone(int ifindex, char **timezone);
 
+/* Get DHCPv4 client id for a given link. */
+int sd_network_link_get_dhcp4_client_id_string(int ifindex, char **client_id);
+
 /* Monitor object */
 typedef struct sd_network_monitor sd_network_monitor;