dhcp: drop NMDhcpClientClass.get_duid() hook

Note that there are no callers of nm_dhcp_client_get_effective_client_id(),
hence calling the setter had no effect. This is a bug, that we will fix
later.

But before fixing the bug, change how this works. Drop the get_duid() hook.
It's only confusing and backward.

We will keep the nm_dhcp_client_[gs]et_effective_client_id() functions.
They will be used later.

src/core/dhcp/nm-dhcp-client.c

@@ -967,12 +967,6 @@ _dhcp_client_decline(NMDhcpClient         *self,
     return klass->decline(self, l3cd, error_message, error);
 }
 
-static GBytes *
-get_duid(NMDhcpClient *self)
-{
-    return NULL;
-}
-
 static gboolean
 ipv6_lladdr_timeout(gpointer user_data)
 {
@@ -1318,11 +1312,6 @@ nm_dhcp_client_start(NMDhcpClient *self, GError **error)
     IS_IPv4 = NM_IS_IPv4(priv->config.addr_family);
 
     if (!IS_IPv4) {
-        if (!priv->config.v6.enforce_duid)
-            own_client_id = NM_DHCP_CLIENT_GET_CLASS(self)->get_duid(self);
-
-        nm_dhcp_client_set_effective_client_id(self, own_client_id ?: priv->config.client_id);
-
         addr = ipv6_lladdr_find(self);
         if (!addr) {
             _LOGD("waiting for IPv6LL address");
@@ -1915,8 +1904,7 @@ nm_dhcp_client_class_init(NMDhcpClientClass *client_class)
     client_class->accept       = _accept;
     client_class->decline      = decline;
 
-    client_class->stop     = stop;
-    client_class->get_duid = get_duid;
+    client_class->stop = stop;
 
     obj_properties[PROP_CONFIG] =
         g_param_spec_pointer(NM_DHCP_CLIENT_CONFIG,

src/core/dhcp/nm-dhcp-client.h

@@ -215,17 +215,6 @@ typedef struct {
     gboolean (*ip6_start)(NMDhcpClient *self, const struct in6_addr *ll_addr, GError **error);
 
     void (*stop)(NMDhcpClient *self, gboolean release);
-
-    /**
-     * get_duid:
-     * @self: the #NMDhcpClient
-     *
-     * Attempts to find an existing DHCPv6 DUID for this client in the DHCP
-     * client's persistent configuration.  Returned DUID should be the binary
-     * representation of the DUID.  If no DUID is found, %NULL should be
-     * returned.
-     */
-    GBytes *(*get_duid)(NMDhcpClient *self);
 } NMDhcpClientClass;
 
 GType nm_dhcp_client_get_type(void);

src/core/dhcp/nm-dhcp-dhclient.c

@@ -627,7 +627,7 @@ stop(NMDhcpClient *client, gboolean release)
     }
 }
 
-static GBytes *
+_nm_unused static GBytes *
 get_duid(NMDhcpClient *client)
 {
     NMDhcpDhclient           *self = NM_DHCP_DHCLIENT(client);
@@ -724,7 +724,6 @@ nm_dhcp_dhclient_class_init(NMDhcpDhclientClass *dhclient_class)
     client_class->ip4_start = ip4_start;
     client_class->ip6_start = ip6_start;
     client_class->stop      = stop;
-    client_class->get_duid  = get_duid;
 }
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_dhclient = {