dhcp: refactor GType handling for NMDhcpClientFactory

In NetworkManager.conf, we can only configure one "[main].dhcp="
for both address families. Consequently, NMDhcpClientFactory
represents also both address families. However, most plugins
don't support IPv4 and IPv6 together.

Thus, if a plugin does not support an address family, we fallback
to the implementation of the "internal" plugin.

Slightly rework the code how that is done. Instead of having
a "get_type()" and "get_type_per_addr_family()" callback, have
an IPv4 and IPv6 getter.

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

@@ -217,8 +217,8 @@ gboolean nm_dhcp_client_server_id_is_rejected(NMDhcpClient *self, gconstpointer
  *****************************************************************************/
 
 typedef struct {
-    GType (*get_type)(void);
-    GType (*get_type_per_addr_family)(int addr_family);
+    GType (*get_type_4)(void);
+    GType (*get_type_6)(void);
     const char *name;
     const char *(*get_path)(void);
     bool experimental : 1;

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

@@ -731,9 +731,10 @@ nm_dhcp_dhclient_class_init(NMDhcpDhclientClass *dhclient_class)
 }
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_dhclient = {
-    .name     = "dhclient",
-    .get_type = nm_dhcp_dhclient_get_type,
-    .get_path = nm_dhcp_dhclient_get_path,
+    .name       = "dhclient",
+    .get_type_4 = nm_dhcp_dhclient_get_type,
+    .get_type_6 = nm_dhcp_dhclient_get_type,
+    .get_path   = nm_dhcp_dhclient_get_path,
 };
 
 #endif /* WITH_DHCLIENT */

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

@@ -232,9 +232,9 @@ nm_dhcp_dhcpcanon_class_init(NMDhcpDhcpcanonClass *dhcpcanon_class)
 }
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_dhcpcanon = {
-    .name     = "dhcpcanon",
-    .get_type = nm_dhcp_dhcpcanon_get_type,
-    .get_path = nm_dhcp_dhcpcanon_get_path,
+    .name       = "dhcpcanon",
+    .get_type_4 = nm_dhcp_dhcpcanon_get_type,
+    .get_path   = nm_dhcp_dhcpcanon_get_path,
 };
 
 #endif /* WITH_DHCPCANON */

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

@@ -233,9 +233,9 @@ nm_dhcp_dhcpcd_class_init(NMDhcpDhcpcdClass *dhcpcd_class)
 }
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_dhcpcd = {
-    .name     = "dhcpcd",
-    .get_type = nm_dhcp_dhcpcd_get_type,
-    .get_path = nm_dhcp_dhcpcd_get_path,
+    .name       = "dhcpcd",
+    .get_type_4 = nm_dhcp_dhcpcd_get_type,
+    .get_path   = nm_dhcp_dhcpcd_get_path,
 };
 
 #endif /* WITH_DHCPCD */

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

@@ -85,11 +85,10 @@ _client_factory_available(const NMDhcpClientFactory *client_factory)
 static GType
 _client_factory_get_gtype(const NMDhcpClientFactory *client_factory, int addr_family)
 {
-    GType                    gtype;
-    nm_auto_unref_gtypeclass NMDhcpClientClass *klass = NULL;
+    GType gtype;
+    GType (*get_type_fcn)(void);
 
     nm_assert(client_factory);
-    nm_assert_addr_family(addr_family);
 
     /* currently, the chosen DHCP plugin for IPv4 and IPv6 is configured in NetworkManager.conf
      * and cannot be reloaded. It would be nice to configure the plugin per address family
@@ -111,29 +110,22 @@ _client_factory_get_gtype(const NMDhcpClientFactory *client_factory, int addr_fa
      * to those plugins. But we don't intend to do so. The internal plugin is the way forward and
      * not extending other plugins. */
 
-    if (client_factory->get_type_per_addr_family)
-        gtype = client_factory->get_type_per_addr_family(addr_family);
+    if (NM_IS_IPv4(addr_family))
+        get_type_fcn = client_factory->get_type_4;
     else
-        gtype = client_factory->get_type();
+        get_type_fcn = client_factory->get_type_6;
 
-    if (client_factory == &_nm_dhcp_client_factory_internal) {
-        /* we are already using the internal plugin. Nothing to do. */
-        goto out;
+    if (!get_type_fcn) {
+        /* If the factory does not support the address family, we always
+         * fallback to the internal. */
+        if (NM_IS_IPv4(addr_family))
+            get_type_fcn = _nm_dhcp_client_factory_internal.get_type_4;
+        else
+            get_type_fcn = _nm_dhcp_client_factory_internal.get_type_6;
     }
 
-    klass = g_type_class_ref(gtype);
+    gtype = get_type_fcn();
 
-    nm_assert(NM_IS_DHCP_CLIENT_CLASS(klass));
-
-    if (addr_family == AF_INET6) {
-        if (!klass->ip6_start)
-            gtype = _client_factory_get_gtype(&_nm_dhcp_client_factory_internal, addr_family);
-    } else {
-        if (!klass->ip4_start)
-            gtype = _client_factory_get_gtype(&_nm_dhcp_client_factory_internal, addr_family);
-    }
-
-out:
     nm_assert(g_type_is_a(gtype, NM_TYPE_DHCP_CLIENT));
     nm_assert(({
         nm_auto_unref_gtypeclass NMDhcpClientClass *k = g_type_class_ref(gtype);

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

@@ -1248,6 +1248,6 @@ nm_dhcp_nettools_class_init(NMDhcpNettoolsClass *class)
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_nettools = {
     .name         = "nettools",
-    .get_type     = nm_dhcp_nettools_get_type,
+    .get_type_4   = nm_dhcp_nettools_get_type,
     .experimental = TRUE,
 };

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

@@ -1124,23 +1124,15 @@ nm_dhcp_systemd_class_init(NMDhcpSystemdClass *sdhcp_class)
 
 const NMDhcpClientFactory _nm_dhcp_client_factory_systemd = {
     .name         = "systemd",
-    .get_type     = nm_dhcp_systemd_get_type,
+    .get_type_4   = nm_dhcp_systemd_get_type,
+    .get_type_6   = nm_dhcp_systemd_get_type,
     .experimental = TRUE,
 };
 
 /*****************************************************************************/
 
-static GType
-_get_type_per_addr_family(int addr_family)
-{
-    nm_assert_addr_family(addr_family);
-
-    if (addr_family == AF_INET)
-        return nm_dhcp_nettools_get_type();
-    return nm_dhcp_systemd_get_type();
-}
-
 const NMDhcpClientFactory _nm_dhcp_client_factory_internal = {
-    .name                     = "internal",
-    .get_type_per_addr_family = _get_type_per_addr_family,
+    .name       = "internal",
+    .get_type_4 = nm_dhcp_nettools_get_type,
+    .get_type_6 = nm_dhcp_systemd_get_type,
 };