extdev: add support for external device handlers

This allows to integrate external daemons that configure network devices with
netifd. At startup, netifd generates device handler stubs from descriptions in
/lib/netifd/extdev-config via the mechanism in handler.c. These are then added
to the list of device handlers. Device handlers stubs act as relays forwarding
calls against the device handler interface to the external daemon.

Signed-off-by: Arne Kappen <arne.kappen@hhi.fraunhofer.de>

1 files changed, 1383 insertions, 0 deletions

diff --git a/extdev.c b/extdev.c
new file mode 100644
index 0000000..9eea0c0
--- /dev/null
+++ b/extdev.c
@@ -0,0 +1,1383 @@
+/*
+ * netifd - network interface daemon
+ * Copyright (C) 2015 Arne Kappen <arne.kappen@hhi.fraunhofer.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ *
+ * extdev - external device handler interface
+ *
+ * This allows to integrate external daemons that configure network devices
+ * with netifd. At startup, netifd generates device handler stubs from
+ * descriptions in /lib/netifd/extdev-config and adds them to the list of
+ * device handlers. A device handler is an instance of struct device_type
+ * The descriptions are in JSON format and specify
+ *   - names of the device type and of the external device handler on ubus,
+ *   - whether the device is bridge-like,
+ *   - a prefix for device names,
+ *   - the UCI config options for devices of this type, and
+ *   - the format of calls to dump() and info()
+ * These device handlers stubs act as relays forwarding calls against the
+ * device handler interface to the external daemon.
+ */
+
+#include <libubox/blobmsg.h>
+#include <libubox/list.h>
+#include <libubus.h>
+#include <assert.h>
+
+#include "netifd.h"
+#include "handler.h"
+#include "device.h"
+#include "ubus.h"
+#include "extdev.h"
+#include "interface.h"
+#include "system.h"
+
+
+static struct blob_buf b;
+static int confdir_fd = -1;
+
+struct extdev_type {
+	struct device_type handler;
+
+	const char *name;
+	uint32_t peer_id;
+	struct ubus_subscriber ubus_sub;
+	bool subscribed;
+	struct ubus_event_handler obj_wait;
+
+	struct uci_blob_param_list *config_params;
+	char *config_strbuf;
+
+	struct uci_blob_param_list *info_params;
+	char *info_strbuf;
+
+	struct uci_blob_param_list *stats_params;
+	char *stats_strbuf;
+};
+
+struct extdev_device {
+	struct device dev;
+	struct extdev_type *etype;
+	const char *dep_name;
+	struct uloop_timeout retry;
+};
+
+struct extdev_bridge {
+	struct extdev_device edev;
+	device_state_cb set_state;
+
+	struct blob_attr *config;
+	bool empty;
+	struct blob_attr *ifnames;
+	bool active;
+	bool force_active;
+
+	struct uloop_timeout retry;
+	struct vlist_tree members;
+	int n_present;
+	int n_failed;
+};
+
+struct extdev_bridge_member {
+	struct vlist_node node;
+	struct extdev_bridge *parent_br;
+	struct device_user dev_usr;
+	bool present;
+	char *name;
+};
+
+static void __bridge_config_init(struct extdev_bridge *ebr);
+static enum dev_change_type __bridge_reload(struct extdev_bridge *ebr, struct blob_attr *config);
+
+enum {
+	METHOD_CREATE,
+	METHOD_CONFIG_INIT,
+	METHOD_RELOAD,
+	METHOD_DUMP_INFO,
+	METHOD_DUMP_STATS,
+	METHOD_CHECK_STATE,
+	METHOD_FREE,
+	METHOD_HOTPLUG_PREPARE,
+	METHOD_HOTPLUG_ADD,
+	METHOD_HOTPLUG_REMOVE,
+	__METHODS_MAX
+};
+
+static const char *__extdev_methods[__METHODS_MAX] = {
+	[METHOD_CREATE] = "create",
+	[METHOD_CONFIG_INIT] = "config_init",
+	[METHOD_RELOAD] = "reload",
+	[METHOD_DUMP_INFO] = "dump_info",
+	[METHOD_DUMP_STATS] = "dump_stats",
+	[METHOD_CHECK_STATE] = "check_state",
+	[METHOD_FREE] = "free",
+	[METHOD_HOTPLUG_PREPARE] = "prepare",
+	[METHOD_HOTPLUG_ADD] = "add",
+	[METHOD_HOTPLUG_REMOVE] = "remove",
+};
+
+static inline int
+netifd_extdev_create(struct extdev_device *edev, struct blob_attr *msg)
+{
+	D(DEVICE, "create %s '%s' at external device handler\n", edev->dev.type->name,
+		edev->dev.ifname);
+	return netifd_extdev_invoke(edev->etype->peer_id, __extdev_methods[METHOD_CREATE], msg,
+				     NULL, NULL);
+}
+
+static inline int
+netifd_extdev_config_init(struct extdev_device *edev, struct blob_attr *msg)
+{
+	return netifd_extdev_invoke(edev->etype->peer_id, __extdev_methods[METHOD_CONFIG_INIT],
+				     msg, NULL, NULL);
+}
+
+static inline int
+netifd_extdev_reload(struct extdev_device *edev, struct blob_attr *msg)
+{
+	D(DEVICE, "reload %s '%s' at external device handler\n", edev->dev.type->name,
+		edev->dev.ifname);
+	return netifd_extdev_invoke(edev->etype->peer_id, __extdev_methods[METHOD_RELOAD], msg,
+				     NULL, NULL);
+}
+
+static inline int
+netifd_extdev_free(struct extdev_device *edev, struct blob_attr *msg)
+{
+	D(DEVICE, "delete %s '%s' with external device handler\n", edev->dev.type->name,
+		edev->dev.ifname);
+	return netifd_extdev_invoke(edev->etype->peer_id, __extdev_methods[METHOD_FREE], msg,
+				     NULL, NULL);
+}
+
+static inline int
+netifd_extdev_prepare(struct extdev_bridge *ebr, struct blob_attr *msg)
+{
+	D(DEVICE, "prepare %s bridge '%s' at external device handler\n", ebr->edev.dev.type->name,
+		ebr->edev.dev.ifname);
+	return netifd_extdev_invoke(ebr->edev.etype->peer_id,
+		__extdev_methods[METHOD_HOTPLUG_PREPARE], msg, NULL, NULL);
+}
+
+static inline int
+netifd_extdev_add(struct extdev_bridge *ebr, struct blob_attr *msg)
+{
+	D(DEVICE, "add a member to %s bridge '%s' at external device handler\n",
+	  ebr->edev.dev.type->name, ebr->edev.dev.ifname);
+	return netifd_extdev_invoke(ebr->edev.etype->peer_id,
+		__extdev_methods[METHOD_HOTPLUG_ADD], msg,NULL, NULL);
+}
+
+static inline int
+netifd_extdev_remove(struct extdev_bridge *ebr, struct blob_attr *msg)
+{
+	D(DEVICE, "remove a member from %s bridge '%s' at external device handler\n",
+	  ebr->edev.dev.type->name, ebr->edev.dev.ifname);
+	return netifd_extdev_invoke(ebr->edev.etype->peer_id,
+		__extdev_methods[METHOD_HOTPLUG_REMOVE], msg, NULL, NULL);
+}
+
+static inline void
+extdev_invocation_error(int error, const char *method, const char *devname)
+{
+	netifd_log_message(L_CRIT, "'%s' failed for '%s': %s\n",
+		method, devname, ubus_strerror(error));
+}
+
+static struct ubus_method extdev_ubus_obj_methods[] = {};
+
+static struct ubus_object_type extdev_ubus_object_type =
+	UBUS_OBJECT_TYPE("netifd_extdev", extdev_ubus_obj_methods);
+
+static int
+extdev_lookup_id(struct extdev_type *etype)
+{
+	int ret = UBUS_STATUS_UNKNOWN_ERROR;
+
+	if (!etype || !etype->name)
+		goto error;
+
+	ret = ubus_lookup_id(ubus_ctx, etype->name, &etype->peer_id);
+	if (ret)
+		goto error;
+
+	return 0;
+
+error:
+	netifd_log_message(L_CRIT, "Could not find '%s' ubus ID: %s\n",
+			   etype->name, ubus_strerror(ret));
+	return ret;
+}
+
+static int
+extdev_ext_ubus_obj_wait(struct ubus_event_handler *h)
+{
+	return ubus_register_event_handler(ubus_ctx, h, "ubus.object.add");
+}
+
+static int
+extdev_subscribe(struct extdev_type *etype)
+{
+	int ret;
+
+	ret = extdev_lookup_id(etype);
+	if (ret) {
+		etype->subscribed = false;
+		return ret;
+	}
+
+	ret = ubus_subscribe(ubus_ctx, &etype->ubus_sub, etype->peer_id);
+	if (ret) {
+		etype->subscribed = false;
+		extdev_ext_ubus_obj_wait(&etype->obj_wait);
+	} else {
+		netifd_log_message(L_NOTICE, "subscribed to external device handler '%s'\n",
+			etype->name);
+		etype->subscribed = true;
+	}
+
+	return ret;
+}
+
+static void
+extdev_wait_ev_cb(struct ubus_context *ctx, struct ubus_event_handler *ev_handler,
+	const char *type, struct blob_attr *msg)
+{
+	static const struct blobmsg_policy wait_policy = {
+		"path", BLOBMSG_TYPE_STRING
+	};
+
+	struct blob_attr *attr;
+	const char *path;
+	struct extdev_type *etype;
+
+	etype = container_of(ev_handler, struct extdev_type, obj_wait);
+
+	if (strcmp(type, "ubus.object.add"))
+		return;
+
+	blobmsg_parse(&wait_policy, 1, &attr, blob_data(msg), blob_len(msg));
+	if (!attr)
+		return;
+
+	path = blobmsg_data(attr);
+	if (strcmp(etype->name, path))
+		return;
+
+	extdev_subscribe(etype);
+}
+
+static int
+extdev_bridge_disable_interface(struct extdev_bridge *ebr)
+{
+	int ret;
+
+	if (!ebr->active)
+		return 0;
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "name", ebr->edev.dev.ifname);
+
+	ret = netifd_extdev_free(&ebr->edev, b.head);
+
+	if (ret && ret != UBUS_STATUS_NOT_FOUND)
+		goto error;
+
+	ebr->active = false;
+	return 0;
+
+error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_FREE], ebr->edev.dev.ifname);
+	return ret;
+}
+
+static int
+extdev_bridge_enable_interface(struct extdev_bridge *ebr)
+{
+	int ret;
+
+	if (ebr->active)
+		return 0;
+
+	ret = netifd_extdev_create(&ebr->edev, ebr->config);
+	if (ret)
+		goto error;
+
+	ebr->active = true;
+	return 0;
+
+error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_CREATE], ebr->edev.dev.ifname);
+	return ret;
+}
+
+static int
+extdev_bridge_enable_member(struct extdev_bridge_member *ubm)
+{
+	int ret;
+	struct extdev_bridge *ebr = ubm->parent_br;
+
+	D(DEVICE, "%s enable member %s\n", ebr->edev.dev.ifname, ubm->name);
+
+	if (!ubm->present)
+		return 0;
+
+	ret = extdev_bridge_enable_interface(ebr);
+	if (ret)
+		goto error;
+
+	ret = device_claim(&ubm->dev_usr);
+	if (ret < 0)
+		goto error;
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "bridge", ebr->edev.dev.ifname);
+	blobmsg_add_string(&b, "member", ubm->dev_usr.dev->ifname);
+
+	/* use hotplug add as addif equivalent. Maybe we need a dedicated ubus
+	 * method on the external handler for this sort of operation. */
+	ret = netifd_extdev_add(ebr, b.head);
+	if (ret) {
+		extdev_invocation_error(ret, __extdev_methods[METHOD_HOTPLUG_ADD],
+					 ubm->dev_usr.dev->ifname);
+		goto error;
+	}
+
+	device_set_present(&ebr->edev.dev, true);
+	device_broadcast_event(&ebr->edev.dev, DEV_EVENT_TOPO_CHANGE);
+
+	return 0;
+
+error:
+	D(DEVICE, "%s: failed to enable member '%s'\n", ebr->edev.dev.ifname, ubm->name);
+
+	ebr->n_failed++;
+	ubm->present = false;
+	ebr->n_present--;
+
+	return ret;
+}
+
+static int
+extdev_bridge_disable_member(struct extdev_bridge_member *ubm)
+{
+	int ret;
+	struct extdev_bridge *ebr = ubm->parent_br;
+
+	if (!ubm->present)
+		return 0;
+
+	D(DEVICE, "%s disable member %s\n", ubm->parent_br->edev.dev.ifname, ubm->name);
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "bridge", ebr->edev.dev.ifname);
+	blobmsg_add_string(&b, "member", ubm->dev_usr.dev->ifname);
+
+	/* use hotplug remove as delif equivalent. Maybe we need a dedicated
+	 * ubus method on the external handler for this sort of operation. */
+	ret = netifd_extdev_remove(ebr, b.head);
+
+	/* continue in case of NOT FOUND since we're trying to remove anyway */
+	if (ret && ret != UBUS_STATUS_NOT_FOUND)
+		goto error;
+
+	device_release(&ubm->dev_usr);
+	device_broadcast_event(&ebr->edev.dev, DEV_EVENT_TOPO_CHANGE);
+
+	return 0;
+
+error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_HOTPLUG_REMOVE],
+			ubm->dev_usr.dev->ifname);
+
+	return ret;
+}
+
+static int
+extdev_bridge_set_down(struct extdev_bridge *ebr)
+{
+	D(DEVICE, "set %s bridge %s down\n", ebr->edev.dev.type->name, ebr->edev.dev.ifname);
+
+	struct extdev_bridge_member *ubm;
+
+	ebr->set_state(&ebr->edev.dev, false);
+
+	vlist_for_each_element(&ebr->members, ubm, node)
+		extdev_bridge_disable_member(ubm);
+
+	extdev_bridge_disable_interface(ebr);
+
+	return 0;
+}
+
+static void
+extdev_bridge_check_retry(struct extdev_bridge *ebr)
+{
+	if (!ebr->n_failed)
+		return;
+
+	uloop_timeout_set(&ebr->retry, 200);
+}
+
+static int
+extdev_bridge_set_up(struct extdev_bridge *ebr)
+{
+	D(DEVICE, "set %s bridge %s up\n", ebr->edev.dev.type->name, ebr->edev.dev.ifname);
+
+	struct extdev_bridge_member *ubm;
+	int ret;
+
+	if (!ebr->n_present) {
+		if (!ebr->force_active)
+			return -ENOENT;
+
+		ret = extdev_bridge_enable_interface(ebr);
+		if (ret)
+			return ret;
+	}
+
+	ebr->n_failed = 0;
+	vlist_for_each_element(&ebr->members, ubm, node)
+		extdev_bridge_enable_member(ubm);
+
+	extdev_bridge_check_retry(ebr);
+
+	if (!ebr->force_active && !ebr->n_present) {
+		extdev_bridge_disable_interface(ebr);
+		device_set_present(&ebr->edev.dev, false);
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
+static int
+extdev_bridge_set_state(struct device *dev, bool up)
+{
+	struct extdev_bridge *ebr;
+
+	if (!dev->type->bridge_capability)
+		return -1;
+
+	ebr = container_of(dev, struct extdev_bridge, edev.dev);
+
+	if (up)
+		return extdev_bridge_set_up(ebr);
+	else
+		return extdev_bridge_set_down(ebr);
+}
+
+static void
+extdev_bridge_remove_member(struct extdev_bridge_member *member)
+{
+	struct extdev_bridge *ebr = member->parent_br;
+
+	if (!member->present)
+		return;
+
+	if (ebr->edev.dev.active)
+		extdev_bridge_disable_member(member);
+
+	member->present = false;
+	ebr->n_present--;
+
+	if (ebr->empty)
+		return;
+
+	ebr->force_active = false;
+	if (ebr->n_present == 0)
+		device_set_present(&ebr->edev.dev, false);
+}
+
+static void
+extdev_bridge_member_cb(struct device_user *usr, enum device_event event)
+{
+	int ret;
+	struct extdev_bridge_member *ubm;
+	struct extdev_bridge *ebr;
+
+	ubm = container_of(usr, struct extdev_bridge_member, dev_usr);
+	ebr = ubm->parent_br;
+
+	switch (event) {
+		case DEV_EVENT_ADD:
+			assert(!ubm->present);
+
+			ubm->present = true;
+			ebr->n_present++;
+
+			/* if this member is the first one that is brought up,
+			 * create the bridge at the external device handler */
+			if (ebr->n_present == 1) {
+				ret = netifd_extdev_create(&ebr->edev, ebr->config);
+				if (ret)
+					goto error;
+
+				ebr->active = true;
+				ret = ebr->set_state(&ebr->edev.dev, true);
+				if (ret < 0)
+					extdev_bridge_set_down(ebr);
+				device_set_present(&ebr->edev.dev, true);
+			}
+
+			extdev_bridge_enable_member(ubm);
+			break;
+		case DEV_EVENT_REMOVE:
+			if (usr->hotplug) {
+				vlist_delete(&ebr->members, &ubm->node);
+				return;
+			}
+
+			if (ubm->present)
+				extdev_bridge_remove_member(ubm);
+			break;
+		default:
+			break;
+	}
+
+	return;
+
+error:
+	netifd_log_message(L_CRIT, "Failed to create %s bridge %s: %s\n",
+			   ebr->edev.dev.type->name, ebr->edev.dev.ifname, ubus_strerror(ret));
+	ubm->present = false;
+	ebr->n_present--;
+}
+
+static void
+__bridge_enable_members(struct extdev_bridge *ebr)
+{
+	struct extdev_bridge_member *cur;
+
+	ebr->n_failed = 0;
+
+	vlist_for_each_element(&ebr->members, cur, node) {
+		if (cur->present)
+			continue;
+
+		if (!cur->dev_usr.dev->present)
+			continue;
+
+		cur->present = true;
+		ebr->n_present++;
+		extdev_bridge_enable_member(cur);
+	}
+}
+
+static void
+extdev_bridge_retry_enable_members(struct uloop_timeout *timeout)
+{
+	struct extdev_bridge *ebr = container_of(timeout, struct extdev_bridge, retry);
+
+	D(DEVICE, "%s retry enable members\n", ebr->edev.dev.ifname);
+
+	__bridge_enable_members(ebr);
+}
+
+static struct extdev_bridge_member *
+extdev_bridge_create_member(struct extdev_bridge *ebr, struct device *dev)
+{
+	struct extdev_bridge_member *ubm;
+	char *name;
+
+	ubm = calloc_a(sizeof(*ubm), &name, strlen(dev->ifname) + 1);
+	if (!ubm)
+		return NULL;
+
+	ubm->parent_br = ebr;
+	ubm->name = name;
+	strcpy(name, dev->ifname);
+	ubm->dev_usr.dev = dev;
+	ubm->dev_usr.cb = extdev_bridge_member_cb;
+	vlist_add(&ebr->members, &ubm->node, ubm->name);
+	/* Need to look up the bridge member again as the above
+	 * created pointer will be freed in case the bridge member
+	 * already existed */
+	ubm = vlist_find(&ebr->members, dev->ifname, ubm, node);
+	if (!ubm)
+		return NULL;
+
+	return ubm;
+}
+
+static void
+extdev_bridge_add_member(struct extdev_bridge *ebr, const char *name)
+{
+	D(DEVICE, "%s add member %s\n", ebr->edev.dev.ifname, name);
+
+	struct device *dev;
+
+	dev = device_get(name, 1);
+	if (!dev)
+		return;
+
+	extdev_bridge_create_member(ebr, dev);
+}
+
+/* TODO: how to handle vlan arg? */
+static int
+extdev_hotplug_add(struct device *ebr_dev, struct device *ebm_dev, struct blob_attr *vlan)
+{
+	D(DEVICE, "%s hotplug add member %s\n", ebr_dev->ifname, ebm_dev->ifname);
+
+	struct extdev_bridge *ebr;
+	struct extdev_bridge_member *ubm;
+
+	if (!ebr_dev->type->bridge_capability)
+		return UBUS_STATUS_NOT_SUPPORTED;
+
+	ebr = container_of(ebr_dev, struct extdev_bridge, edev.dev);
+
+	if (!ebr->edev.etype->subscribed)
+		return UBUS_STATUS_NOT_FOUND;
+
+	ubm = extdev_bridge_create_member(ebr, ebm_dev);
+	if (!ubm)
+		return UBUS_STATUS_UNKNOWN_ERROR;
+
+	device_broadcast_event(&ebr->edev.dev, DEV_EVENT_TOPO_CHANGE);
+
+	return 0;
+}
+
+static int
+extdev_hotplug_remove(struct device *dev, struct device *member)
+{
+	struct extdev_bridge *ebr;
+	struct extdev_bridge_member *ubm;
+
+	if (!dev->type->bridge_capability)
+		return UBUS_STATUS_NOT_SUPPORTED;
+
+	ebr = container_of(dev, struct extdev_bridge, edev.dev);
+
+	if (!ebr->edev.etype->subscribed)
+		return UBUS_STATUS_NOT_FOUND;
+
+	ubm = vlist_find(&ebr->members, member->ifname, ubm, node);
+	if (!ubm)
+		return UBUS_STATUS_NOT_FOUND;
+
+	vlist_delete(&ebr->members, &ubm->node);
+	extdev_bridge_remove_member(ubm);
+
+	return 0;
+}
+
+static int
+extdev_hotplug_prepare(struct device *dev, struct device **bridge_dev)
+{
+	struct extdev_bridge *ebr;
+	int ret;
+
+	if (!dev->type->bridge_capability)
+		return UBUS_STATUS_NOT_SUPPORTED;
+
+	if (bridge_dev)
+		*bridge_dev = dev;
+
+	ebr = container_of(dev, struct extdev_bridge, edev.dev);
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "name", dev->ifname);
+
+	ret = netifd_extdev_prepare(ebr, b.head);
+	if (ret)
+		goto error;
+
+	ebr->force_active = true;
+	device_set_present(&ebr->edev.dev, true);
+
+	return 0;
+
+error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_HOTPLUG_PREPARE], dev->ifname);
+	return ret;
+}
+
+static void
+extdev_bridge_free_member(struct extdev_bridge_member *ubm)
+{
+	struct device *dev = ubm->dev_usr.dev;
+
+	extdev_bridge_remove_member(ubm);
+	device_remove_user(&ubm->dev_usr);
+
+	if (dev->present) {
+		device_set_present(dev, false);
+		device_set_present(dev, true);
+	}
+
+	free(ubm);
+}
+
+static void
+extdev_bridge_member_update(struct vlist_tree *tree, struct vlist_node *node_new,
+			     struct vlist_node *node_old)
+{
+	struct extdev_bridge_member *ubm;
+	struct device *dev;
+
+	if (node_new) {
+		ubm = container_of(node_new, struct extdev_bridge_member, node);
+
+		if (node_old) {
+			free(ubm);
+			return;
+		}
+
+		dev = ubm->dev_usr.dev;
+		ubm->dev_usr.dev = NULL;
+		device_add_user(&ubm->dev_usr, dev);
+	}
+
+	if (node_old) {
+		ubm = container_of(node_old, struct extdev_bridge_member, node);
+		extdev_bridge_free_member(ubm);
+	}
+}
+
+
+static void
+bridge_dependency_retry(struct uloop_timeout *timeout)
+{
+	struct extdev_bridge *ebr;
+
+	ebr = container_of(timeout, struct extdev_bridge, edev.retry);
+
+	__bridge_reload(ebr, NULL);
+}
+
+static void
+__buf_add_all(struct blob_attr *attr)
+{
+	struct blob_attr *cur;
+	int rem;
+
+	blobmsg_for_each_attr(cur, attr, rem)
+		blobmsg_add_field(&b, blobmsg_type(cur), blobmsg_name(cur), blobmsg_data(cur),
+			blobmsg_data_len(cur));
+}
+
+enum {
+	BRIDGE_EMPTY,
+	BRIDGE_IFNAMES,
+	BRIDGE_DEPENDS_ON,
+	__BRIDGE_MAX
+};
+
+static const struct blobmsg_policy brpol[__BRIDGE_MAX] = {
+	[BRIDGE_EMPTY] = { "empty",  BLOBMSG_TYPE_BOOL },
+	[BRIDGE_IFNAMES] = { "ifname", BLOBMSG_TYPE_ARRAY },
+	[BRIDGE_DEPENDS_ON] = { "depends_on", BLOBMSG_TYPE_STRING },
+};
+
+static enum dev_change_type
+__do_bridge_reload(struct extdev_bridge *ebr, struct blob_attr *config)
+{
+	void *cfg_table;
+	int ret;
+
+	blob_buf_init(&b, 0);
+	cfg_table = blobmsg_open_table(&b, "old");
+	__buf_add_all(ebr->config);
+	blobmsg_close_table(&b, cfg_table);
+	cfg_table = blobmsg_open_table(&b, "new");
+	__buf_add_all(config);
+	blobmsg_close_table(&b, cfg_table);
+
+	ret = netifd_extdev_reload(&ebr->edev, b.head);
+
+	if (ret) {
+		netifd_log_message(L_WARNING, "%s config reload failed: %s\n",
+				   ebr->edev.dev.ifname, ubus_strerror(ret));
+		return DEV_CONFIG_RECREATE;
+	} else {
+		return DEV_CONFIG_RESTART;
+	}
+}
+
+static enum dev_change_type
+__bridge_reload(struct extdev_bridge *ebr, struct blob_attr *config)
+{
+	int n_params = ebr->edev.dev.type->config_params->n_params;
+	struct blob_attr *tb[__BRIDGE_MAX];
+	const struct uci_blob_param_list *config_params;
+	const struct blobmsg_policy *pol;
+	struct blob_attr *old_tb[n_params], *brtb[n_params];
+	enum dev_change_type change = DEV_CONFIG_APPLIED;
+	struct device *dev;
+	unsigned long diff = 0;
+
+	if (config) {
+		config = blob_memdup(config);
+		blobmsg_parse(brpol, __BRIDGE_MAX, tb, blobmsg_data(config), blobmsg_len(config));
+		ebr->edev.dep_name = blobmsg_get_string(tb[BRIDGE_DEPENDS_ON]);
+
+		if (tb[BRIDGE_EMPTY] && blobmsg_get_bool(tb[BRIDGE_EMPTY]))
+			ebr->empty = true;
+
+		if (ebr->config) {
+			config_params = ebr->edev.dev.type->config_params;
+			pol = config_params->params;
+
+			blobmsg_parse(pol, n_params, old_tb, blobmsg_data(ebr->config),
+				blobmsg_len(ebr->config));
+			blobmsg_parse(pol, n_params, brtb, blobmsg_data(config), blobmsg_len
+			(config));
+
+			diff = 0;
+			uci_blob_diff(brtb, old_tb, config_params, &diff);
+			if (diff) {
+				if (diff & ~(1 << BRIDGE_IFNAMES)) {
+					change = DEV_CONFIG_RESTART;
+				} else {
+					change = __do_bridge_reload(ebr, config);
+				}
+
+				free(ebr->config);
+			}
+		}
+
+		ebr->ifnames = tb[BRIDGE_IFNAMES];
+		ebr->config = config;
+	}
+
+	if (ebr->edev.dep_name) {
+		dev = device_get(ebr->edev.dep_name, 0);
+		if (!(dev && dev->current_config)) {
+			D(DEVICE, "%s: cannot yet init config since dependency '%s' is not ready\n",
+			  ebr->edev.dev.ifname, ebr->edev.dep_name);
+			ebr->edev.retry.cb = bridge_dependency_retry;
+			uloop_timeout_set(&ebr->edev.retry, 200);
+			return DEV_CONFIG_RESTART;
+		}
+	}
+
+	__bridge_config_init(ebr);
+	ebr->edev.dev.config_pending = false;
+	uloop_timeout_cancel(&ebr->edev.retry);
+
+	return change;
+}
+
+static enum dev_change_type
+__reload(struct extdev_device *edev, struct blob_attr *config)
+{
+	unsigned long diff = 0;
+	struct uci_blob_param_list *params;
+
+	params = edev->etype->config_params;
+
+	struct blob_attr *tb[params->n_params];
+	struct blob_attr *old_tb[params->n_params];
+
+	blobmsg_parse(params->params, params->n_params,	tb, blobmsg_data(config),
+		blobmsg_len(config));
+	blobmsg_parse(params->params, params->n_params,	old_tb, blobmsg_data(edev->dev.config),
+		blobmsg_len(edev->dev.config));
+
+	uci_blob_diff(tb, old_tb, edev->etype->config_params, &diff);
+	if (!diff)
+		return DEV_CONFIG_NO_CHANGE;
+
+	// TODO: make reload ubus call with old and new config
+
+	device_set_present(&edev->dev, false);
+	device_set_present(&edev->dev, true);
+
+	return DEV_CONFIG_APPLIED;
+}
+
+static enum dev_change_type
+extdev_reload(struct device *dev, struct blob_attr *config)
+{
+	struct extdev_type *etype;
+	struct extdev_device *edev;
+	struct extdev_bridge *ebr;
+
+	etype = container_of(dev->type, struct extdev_type, handler);
+
+	if (!etype->subscribed)
+		return DEV_CONFIG_NO_CHANGE;
+
+	edev = container_of(dev, struct extdev_device, dev);
+
+	if (dev->type->bridge_capability) {
+		ebr = container_of(edev, struct extdev_bridge, edev);
+		return __bridge_reload(ebr, config);
+	} else {
+		return __reload(edev, config);
+	}
+}
+
+static struct device*
+__create(const char *name, struct device_type *type, struct blob_attr *config)
+{
+	struct extdev_device *edev;
+	struct extdev_type *etype;
+	int ret;
+
+	etype = container_of(type, struct extdev_type, handler);
+	edev = calloc(1, sizeof(struct extdev_device));
+	if (!edev)
+		return NULL;
+
+	ret = device_init(&edev->dev, type, name);
+	if (ret)
+		goto error;
+
+	edev->etype = etype;
+
+	ret = netifd_extdev_create(edev, config);
+	if (ret)
+		goto inv_error;
+
+	edev->dev.config_pending = false;
+
+	return &edev->dev;
+
+inv_error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_CREATE], name);
+error:
+	device_lock();
+	free(edev->dev.config);
+	device_cleanup(&edev->dev);
+	free(edev);
+	device_unlock();
+	netifd_log_message(L_WARNING, "Failed to create %s %s\n", type->name, name);
+	return NULL;
+}
+
+static const struct device_hotplug_ops extdev_hotplug_ops = {
+	.prepare = extdev_hotplug_prepare,
+	.add = extdev_hotplug_add,
+	.del = extdev_hotplug_remove
+};
+
+static struct device*
+__bridge_create(const char *name, struct device_type *devtype, struct blob_attr *config)
+{
+	struct extdev_bridge *ebr;
+
+	ebr = calloc(1, sizeof(*ebr));
+	if (!ebr)
+		return NULL;
+
+	device_init(&ebr->edev.dev, devtype, name);
+	ebr->edev.dev.config_pending = true;
+	ebr->retry.cb = extdev_bridge_retry_enable_members;
+	ebr->edev.etype = container_of(devtype, struct extdev_type, handler);
+	ebr->set_state = ebr->edev.dev.set_state;
+	ebr->edev.dev.set_state = extdev_bridge_set_state;
+	ebr->edev.dev.hotplug_ops = &extdev_hotplug_ops;
+	vlist_init(&ebr->members, avl_strcmp, extdev_bridge_member_update);
+	ebr->members.keep_old = true;
+	__bridge_reload(ebr, config);
+
+	return &ebr->edev.dev;
+}
+
+/* Device creation process:
+ * For bridges without dependencies:
+ *  1) The bridge state is initialized in netifd. Devices for the members are
+ *     created and added to the members vlist by config_init automatically.
+ *  2) When the first bridge member device is brought up in
+ *     extdev_bridge_enable_member the 'create' call to the external device
+ *     handler is issued.
+ *  3) After successful device creation the bridge is marked "present" and a
+ *     new attempt at adding the member is made.
+ * For bridges with dependencies:
+ *  1) The bridge state is initialized in netifd. If a dependency is expressed
+ *     via the 'depends_on' UCI option and the dependency is not ready (i.e. it
+ *     does not exist or config_pending == true) the call to
+ *     __bridge_config_init() is postponed and a retry timer is started. Retries
+ *     happen until the dependency is ready. Then, __bridge_config_init() gets
+ *     called and the process continues as with bridges without dependencies
+ * For regular devices:
+ *  1) The device structure is created in netifd.
+ *  2) config_init is called automatically which issues the 'create' call to the
+ *     external device handler.
+ */
+static struct device *
+extdev_create(const char *name, struct device_type *devtype, struct blob_attr *config)
+{
+	struct extdev_type *etype = container_of(devtype, struct extdev_type, handler);
+
+	if (!etype->subscribed)
+		return NULL;
+
+	if (devtype->bridge_capability)
+		return __bridge_create(name, devtype, config);
+	else
+		return __create(name, devtype, config);
+}
+
+static void
+extdev_free(struct device *dev)
+{
+	struct extdev_type *etype;
+	struct extdev_device *edev;
+	struct extdev_bridge *ebr;
+	int ret;
+
+	etype = container_of(dev->type, struct extdev_type, handler);
+	edev = container_of(dev, struct extdev_device, dev);
+
+	if (!etype->subscribed)
+		return;
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "name", dev->ifname);
+
+	ret = netifd_extdev_free(edev, b.head);
+
+	if (ret && ret != UBUS_STATUS_NOT_FOUND)
+		goto error;
+
+	if (dev->type->bridge_capability) {
+		ebr = container_of(dev, struct extdev_bridge, edev.dev);
+
+		vlist_flush_all(&ebr->members);
+//		vlist_flush_all(&dev->vlans); TODO: do we need this?
+
+		free(ebr->config);
+		free(ebr);
+	}
+
+	return;
+
+error:
+	extdev_invocation_error(ret, __extdev_methods[METHOD_FREE],
+		dev->ifname);
+}
+
+static void
+__bridge_config_init(struct extdev_bridge *ebr)
+{
+	int rem, ret;
+	struct blob_attr *cur;
+
+	if (ebr->empty) {
+		ebr->force_active = true;
+		ret = netifd_extdev_create(&ebr->edev, ebr->config);
+		if (ret)
+			goto error;
+		device_set_present(&ebr->edev.dev, true);
+	}
+
+	ebr->n_failed = 0;
+	vlist_update(&ebr->members);
+	if (ebr->ifnames) {
+		blobmsg_for_each_attr(cur, ebr->ifnames, rem)
+			extdev_bridge_add_member(ebr, blobmsg_data(cur));
+	}
+
+	vlist_flush(&ebr->members);
+	extdev_bridge_check_retry(ebr);
+	return;
+
+error:
+	fprintf(stderr, "Failed to init config for '%s': %s\n", ebr->edev.dev.ifname,
+		ubus_strerror(ret));
+}
+
+static void
+extdev_config_init(struct device *dev)
+{
+	struct extdev_type *etype;
+	struct extdev_bridge *ebr;
+
+	etype = container_of(dev->type, struct extdev_type, handler);
+
+	if (!etype->subscribed)
+		return;
+
+	if (dev->type->bridge_capability) {
+		ebr = container_of(dev, struct extdev_bridge, edev.dev);
+		__bridge_config_init(ebr);
+	}
+}
+
+static void
+extdev_buf_add_list(struct blob_attr *attr, int len, const char *name,
+		     struct blob_buf *buf, bool array)
+{
+	struct blob_attr *cur;
+	struct blobmsg_hdr *hdr;
+	void *list;
+	int type;
+
+	if (array)
+		list = blobmsg_open_array(buf, name);
+	else
+		list = blobmsg_open_table(buf, name);
+
+	blobmsg_for_each_attr(cur, attr, len) {
+		hdr = blob_data(cur);
+		type = blobmsg_type(cur);
+		switch (type) {
+			case BLOBMSG_TYPE_STRING:
+				blobmsg_add_string(buf, (char *) hdr->name,
+					blobmsg_get_string(cur));
+				break;
+			case BLOBMSG_TYPE_TABLE:
+			case BLOBMSG_TYPE_ARRAY:
+				extdev_buf_add_list(blobmsg_data(cur), blobmsg_data_len(cur),
+					(char *) hdr->name, buf, type == BLOBMSG_TYPE_ARRAY);
+				break;
+			case BLOBMSG_TYPE_INT64:
+				blobmsg_add_u64(buf, (char *) hdr->name, blobmsg_get_u64(cur));
+				break;
+			case BLOBMSG_TYPE_INT32:
+				blobmsg_add_u32(buf, (char *) hdr->name, blobmsg_get_u32(cur));
+				break;
+			case BLOBMSG_TYPE_INT16:
+				blobmsg_add_u16(buf, (char *) hdr->name, blobmsg_get_u16(cur));
+				break;
+			case BLOBMSG_TYPE_INT8:
+				blobmsg_add_u8(buf, (char *) hdr->name, blobmsg_get_u8(cur));
+				break;
+			default:
+				break;
+		}
+	}
+
+	if (array)
+		blobmsg_close_array(buf, list);
+	else
+		blobmsg_close_table(buf, list);
+}
+
+static void
+add_parsed_data(struct blob_attr **tb, const struct blobmsg_policy *policy, int n_params,
+		struct blob_buf *buf)
+{
+	for (int i = 0; i < n_params; i++) {
+		if (!tb[i])
+			continue;
+
+		switch (policy[i].type) {
+			case BLOBMSG_TYPE_STRING:
+				blobmsg_add_string(buf, policy[i].name, blobmsg_get_string(tb[i]));
+				break;
+			case BLOBMSG_TYPE_ARRAY:
+			case BLOBMSG_TYPE_TABLE:
+				extdev_buf_add_list(blobmsg_data(tb[i]), blobmsg_data_len(tb[i]),
+					policy[i].name, buf, policy[i].type == BLOBMSG_TYPE_ARRAY);
+				break;
+			case BLOBMSG_TYPE_INT64:
+				blobmsg_add_u64(buf, policy[i].name, blobmsg_get_u64(tb[i]));
+				break;
+			case BLOBMSG_TYPE_INT32:
+				blobmsg_add_u32(buf, policy[i].name, blobmsg_get_u32(tb[i]));
+				break;
+			case BLOBMSG_TYPE_INT16:
+				blobmsg_add_u16(buf, policy[i].name, blobmsg_get_u16(tb[i]));
+				break;
+			case BLOBMSG_TYPE_INT8:
+				blobmsg_add_u8(buf, policy[i].name, blobmsg_get_u8(tb[i]));
+				break;
+			default:
+				break;
+		}
+	}
+}
+
+struct dump_data {
+	const struct device *dev;
+	struct blob_buf *buf;
+};
+
+static void
+dump_cb(struct ubus_request *req, int type, struct blob_attr *reply)
+{
+	struct dump_data *data;
+	struct extdev_type *etype;
+	const struct blobmsg_policy *info_policy;
+	int n_params;
+	struct blob_buf *buf;
+
+	data = req->priv;
+	etype = container_of(data->dev->type, struct extdev_type, handler);
+	info_policy = etype->info_params->params;
+	n_params = etype->info_params->n_params;
+	buf = data->buf;
+
+	struct blob_attr *tb[n_params];
+
+	blobmsg_parse(info_policy, n_params, tb, blobmsg_data(reply), blobmsg_len(reply));
+	add_parsed_data(tb, info_policy, n_params, buf);
+}
+
+static void
+extdev_dump(const char *method, struct device *dev, struct blob_buf *buf)
+{
+	static struct dump_data data;
+	struct extdev_type *etype;
+
+	etype = container_of(dev->type, struct extdev_type, handler);
+
+	if (!etype->subscribed)
+		return;
+
+	data.dev = dev;
+	data.buf = buf;
+
+	blob_buf_init(&b, 0);
+	blobmsg_add_string(&b, "name", dev->ifname);
+
+	netifd_extdev_invoke(etype->peer_id, method, b.head, dump_cb, &data);
+}
+
+static void
+extdev_dump_info(struct device *dev, struct blob_buf *buf)
+{
+	extdev_dump(__extdev_methods[METHOD_DUMP_INFO], dev, buf);
+}
+
+static void
+extdev_dump_stats(struct device *dev, struct blob_buf *buf)
+{
+	extdev_dump(__extdev_methods[METHOD_DUMP_STATS], dev, buf);
+}
+
+static void
+extdev_ext_handler_remove_cb(struct ubus_context *ctx,
+			      struct ubus_subscriber *obj, uint32_t id)
+{
+	struct extdev_type *etype;
+	etype = container_of(obj, struct extdev_type, ubus_sub);
+
+	netifd_log_message(L_NOTICE, "%s: external device handler "
+		"'%s' disappeared. Waiting for it to re-appear.\n",
+		etype->handler.name, etype->name);
+
+	etype->peer_id = 0;
+	etype->subscribed = false;
+
+	extdev_ext_ubus_obj_wait(&etype->obj_wait);
+}
+
+static void
+extdev_add_devtype(const char *cfg_file, const char *tname, const char *ubus_name,
+		    bool bridge_capability, const char *br_prefix, json_object *cfg_obj,
+		    json_object *info_obj, json_object *stats_obj)
+{
+	static const char *OBJ_PREFIX = "network.device.";
+
+	struct extdev_type *etype;
+	struct device_type *devtype;
+	char *ubus_obj_name, *devtype_name, *ext_dev_handler_name, *name_prefix;
+	struct uci_blob_param_list *config_params, *info_params, *stats_params;
+	int ret;
+
+	etype = calloc_a(sizeof(*etype),
+		&ubus_obj_name, strlen(OBJ_PREFIX) + strlen(ubus_name) + 1,
+		&devtype_name, strlen(tname) + 1,
+		&ext_dev_handler_name, strlen(ubus_name) + 1,
+		&config_params, sizeof(struct uci_blob_param_list),
+		&info_params, sizeof(struct uci_blob_param_list),
+		&stats_params, sizeof(struct uci_blob_param_list));
+
+	if (!etype)
+		return;
+
+	etype->config_params = config_params;
+	etype->info_params = info_params;
+	etype->name = strcpy(ext_dev_handler_name, ubus_name);
+
+	devtype = &etype->handler;
+	devtype->name = strcpy(devtype_name, tname);
+	devtype->create = extdev_create;
+	devtype->free = extdev_free;
+	devtype->config_init = extdev_config_init;
+	devtype->reload = extdev_reload;
+	devtype->dump_info = extdev_dump_info;
+	devtype->dump_stats = extdev_dump_stats;
+	devtype->bridge_capability = bridge_capability;
+	devtype->config_params = etype->config_params;
+
+	if (bridge_capability) {
+		name_prefix = malloc(strlen(br_prefix) + 1);
+		if (!name_prefix)
+			goto error;
+
+		strcpy(name_prefix, br_prefix);
+		devtype->name_prefix = name_prefix;
+	}
+
+	/* subscribe to external device handler */
+	sprintf(ubus_obj_name, "%s%s", OBJ_PREFIX,  ubus_name);
+	etype->ubus_sub.obj.name = ubus_obj_name;
+	etype->ubus_sub.obj.type = &extdev_ubus_object_type;
+	ret = ubus_register_subscriber(ubus_ctx, &etype->ubus_sub);
+	if (ret) {
+		fprintf(stderr, "Failed to register subscriber object '%s'\n",
+			etype->ubus_sub.obj.name);
+		goto error;
+	}
+	etype->obj_wait.cb = extdev_wait_ev_cb;
+	etype->ubus_sub.remove_cb = extdev_ext_handler_remove_cb;
+	extdev_subscribe(etype);
+
+	/* parse config params from JSON object */
+	etype->config_strbuf = netifd_handler_parse_config(etype->config_params, cfg_obj);
+	if (!etype->config_strbuf)
+		goto error;
+
+	/* parse info dump params from JSON object */
+	if (!info_obj) {
+		devtype->dump_info = NULL;
+	} else {
+		etype->info_strbuf = netifd_handler_parse_config(etype->info_params, info_obj);
+		if (!etype->info_strbuf)
+			devtype->dump_info = NULL;
+	}
+
+	/* parse statistics dump params from JSON object */
+	if (!stats_obj) {
+		devtype->dump_stats = NULL;
+	} else {
+		etype->stats_strbuf = netifd_handler_parse_config(etype->stats_params, stats_obj);
+		if (!etype->stats_strbuf)
+			devtype->dump_stats = NULL;
+	}
+
+	ret = device_type_add(devtype);
+	if (ret)
+		goto config_error;
+
+	return;
+
+config_error:
+	free(etype->config_strbuf);
+	free(etype->info_strbuf);
+	free(etype->stats_strbuf);
+
+error:
+	fprintf(stderr, "Failed to create device handler for device"
+		"type '%s' from file '%s'\n", tname, cfg_file);
+	free(ubus_obj_name);
+	free(devtype_name);
+	free(etype);
+}
+
+/* create extdev device handler stubs from JSON description */
+void
+extdev_init(void)
+{
+	confdir_fd = netifd_open_subdir("extdev-config");
+	if (confdir_fd < 0)
+		return;
+	netifd_init_extdev_handlers(confdir_fd, extdev_add_devtype);
+}