libhydra: Move kernel interface to libcharon

This moves hydra->kernel_interface to charon->kernel.

src/libcharon/kernel/kernel_handler.c

@@ -15,7 +15,6 @@
 
 #include "kernel_handler.h"
 
-#include <hydra.h>
 #include <daemon.h>
 #include <processing/jobs/acquire_job.h>
 #include <processing/jobs/delete_child_sa_job.h>
@@ -135,8 +134,7 @@ METHOD(kernel_listener_t, roam, bool,
 METHOD(kernel_handler_t, destroy, void,
 	private_kernel_handler_t *this)
 {
-	hydra->kernel_interface->remove_listener(hydra->kernel_interface,
-											 &this->public.listener);
+	charon->kernel->remove_listener(charon->kernel, &this->public.listener);
 	free(this);
 }
 
@@ -157,8 +155,7 @@ kernel_handler_t *kernel_handler_create()
 		},
 	);
 
-	hydra->kernel_interface->add_listener(hydra->kernel_interface,
-										  &this->public.listener);
+	charon->kernel->add_listener(charon->kernel, &this->public.listener);
 
 	return &this->public;
 }

src/libcharon/kernel/kernel_handler.h

@@ -15,7 +15,7 @@
 
 /**
  * @defgroup kernel_handler kernel_handler
- * @{ @ingroup ckernel
+ * @{ @ingroup kernel
  */
 
 #ifndef KERNEL_HANDLER_H_

src/libcharon/kernel/kernel_interface.h

@@ -0,0 +1,655 @@
+/*
+ * Copyright (C) 2006-2015 Tobias Brunner
+ * Copyright (C) 2006 Daniel Roethlisberger
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+/*
+ * Copyright (c) 2012 Nanoteq Pty Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/**
+ * @defgroup kernel_interface kernel_interface
+ * @{ @ingroup kernel
+ */
+
+#ifndef KERNEL_INTERFACE_H_
+#define KERNEL_INTERFACE_H_
+
+typedef struct kernel_interface_t kernel_interface_t;
+typedef enum kernel_feature_t kernel_feature_t;
+
+#include <networking/host.h>
+#include <crypto/prf_plus.h>
+
+#include <kernel/kernel_listener.h>
+#include <kernel/kernel_ipsec.h>
+#include <kernel/kernel_net.h>
+
+/**
+ * Bitfield of optional features a kernel backend supports.
+ *
+ * This feature-set is for both, kernel_ipsec_t and kernel_net_t. Each
+ * backend returns a subset of these features.
+ */
+enum kernel_feature_t {
+	/** IPsec can process ESPv3 (RFC 4303) TFC padded packets */
+	KERNEL_ESP_V3_TFC = (1<<0),
+	/** Networking requires an "exclude" route for IKE/ESP packets */
+	KERNEL_REQUIRE_EXCLUDE_ROUTE = (1<<1),
+	/** IPsec implementation requires UDP encapsulation of ESP packets */
+	KERNEL_REQUIRE_UDP_ENCAPSULATION = (1<<2),
+	/** IPsec backend does not require a policy reinstall on SA updates */
+	KERNEL_NO_POLICY_UPDATES = (1<<3),
+};
+
+/**
+ * Constructor function for ipsec kernel interface
+ */
+typedef kernel_ipsec_t* (*kernel_ipsec_constructor_t)(void);
+
+/**
+ * Constructor function for network kernel interface
+ */
+typedef kernel_net_t* (*kernel_net_constructor_t)(void);
+
+/**
+ * Manager and wrapper for different kernel interfaces.
+ *
+ * The kernel interface handles the communication with the kernel
+ * for SA and policy management and interface and IP address management.
+ */
+struct kernel_interface_t {
+
+	/**
+	 * Get the feature set supported by the net and ipsec kernel backends.
+	 *
+	 * @return				ORed feature-set of backends
+	 */
+	kernel_feature_t (*get_features)(kernel_interface_t *this);
+
+	/**
+	 * Get a SPI from the kernel.
+	 *
+	 * @param src		source address of SA
+	 * @param dst		destination address of SA
+	 * @param protocol	protocol for SA (ESP/AH)
+	 * @param spi		allocated spi
+	 * @return			SUCCESS if operation completed
+	 */
+	status_t (*get_spi)(kernel_interface_t *this, host_t *src, host_t *dst,
+						u_int8_t protocol, u_int32_t *spi);
+
+	/**
+	 * Get a Compression Parameter Index (CPI) from the kernel.
+	 *
+	 * @param src		source address of SA
+	 * @param dst		destination address of SA
+	 * @param cpi		allocated cpi
+	 * @return			SUCCESS if operation completed
+	 */
+	status_t (*get_cpi)(kernel_interface_t *this, host_t *src, host_t *dst,
+						u_int16_t *cpi);
+
+	/**
+	 * Allocate or confirm a reqid to use for a given SA pair.
+	 *
+	 * Each returned reqid by a successful call to alloc_reqid() must be
+	 * released using release_reqid().
+	 *
+	 * The reqid parameter is an in/out parameter. If it points to non-zero,
+	 * the reqid is confirmed and registered for use. If it points to zero,
+	 * a reqid is allocated for the given selectors, and returned to reqid.
+	 *
+	 * @param local_ts	traffic selectors of local side for SA
+	 * @param remote_ts	traffic selectors of remote side for SA
+	 * @param mark_in	inbound mark on SA
+	 * @param mark_out	outbound mark on SA
+	 * @param reqid		allocated reqid
+	 * @return			SUCCESS if reqid allocated
+	 */
+	status_t (*alloc_reqid)(kernel_interface_t *this,
+							linked_list_t *local_ts, linked_list_t *remote_ts,
+							mark_t mark_in, mark_t mark_out,
+							u_int32_t *reqid);
+
+	/**
+	 * Release a previously allocated reqid.
+	 *
+	 * @param reqid		reqid to release
+	 * @param mark_in	inbound mark on SA
+	 * @param mark_out	outbound mark on SA
+	 * @return			SUCCESS if reqid released
+	 */
+	status_t (*release_reqid)(kernel_interface_t *this, u_int32_t reqid,
+							  mark_t mark_in, mark_t mark_out);
+
+	/**
+	 * Add an SA to the SAD.
+	 *
+	 * This function does install a single SA for a single protocol in one
+	 * direction.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param reqid			reqid for this SA
+	 * @param mark			optional mark for this SA
+	 * @param tfc			Traffic Flow Confidentiality padding for this SA
+	 * @param lifetime		lifetime_cfg_t for this SA
+	 * @param enc_alg		Algorithm to use for encryption (ESP only)
+	 * @param enc_key		key to use for encryption
+	 * @param int_alg		Algorithm to use for integrity protection
+	 * @param int_key		key to use for integrity protection
+	 * @param mode			mode of the SA (tunnel, transport)
+	 * @param ipcomp		IPComp transform to use
+	 * @param cpi			CPI for IPComp
+	 * @param replay_window	anti-replay window size
+	 * @param initiator		TRUE if initiator of the exchange creating this SA
+	 * @param encap			enable UDP encapsulation for NAT traversal
+	 * @param esn			TRUE to use Extended Sequence Numbers
+	 * @param inbound		TRUE if this is an inbound SA
+	 * @param update		TRUE if an SPI has already been allocated for SA
+	 * @param src_ts		list of source traffic selectors
+	 * @param dst_ts		list of destination traffic selectors
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_sa) (kernel_interface_t *this,
+						host_t *src, host_t *dst, u_int32_t spi,
+						u_int8_t protocol, u_int32_t reqid, mark_t mark,
+						u_int32_t tfc, lifetime_cfg_t *lifetime,
+						u_int16_t enc_alg, chunk_t enc_key,
+						u_int16_t int_alg, chunk_t int_key,
+						ipsec_mode_t mode, u_int16_t ipcomp, u_int16_t cpi,
+						u_int32_t replay_window, bool initiator, bool encap,
+						bool esn, bool inbound, bool update,
+						linked_list_t *src_ts, linked_list_t *dst_ts);
+
+	/**
+	 * Update the hosts on an installed SA.
+	 *
+	 * We cannot directly update the destination address as the kernel
+	 * requires the spi, the protocol AND the destination address (and family)
+	 * to identify SAs. Therefore if the destination address changed we
+	 * create a new SA and delete the old one.
+	 *
+	 * @param spi			SPI of the SA
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param cpi			CPI for IPComp, 0 if no IPComp is used
+	 * @param src			current source address
+	 * @param dst			current destination address
+	 * @param new_src		new source address
+	 * @param new_dst		new destination address
+	 * @param encap			current use of UDP encapsulation
+	 * @param new_encap		new use of UDP encapsulation
+	 * @param mark			optional mark for this SA
+	 * @return				SUCCESS if operation completed, NOT_SUPPORTED if
+	 *					  the kernel interface can't update the SA
+	 */
+	status_t (*update_sa)(kernel_interface_t *this,
+						  u_int32_t spi, u_int8_t protocol, u_int16_t cpi,
+						  host_t *src, host_t *dst,
+						  host_t *new_src, host_t *new_dst,
+						  bool encap, bool new_encap, mark_t mark);
+
+	/**
+	 * Query the number of bytes processed by an SA from the SAD.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param mark			optional mark for this SA
+	 * @param[out] bytes	the number of bytes processed by SA
+	 * @param[out] packets	number of packets processed by SA
+	 * @param[out] time		last (monotonic) time of SA use
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*query_sa) (kernel_interface_t *this, host_t *src, host_t *dst,
+						  u_int32_t spi, u_int8_t protocol, mark_t mark,
+						  u_int64_t *bytes, u_int64_t *packets, time_t *time);
+
+	/**
+	 * Delete a previously installed SA from the SAD.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param cpi			CPI for IPComp or 0
+	 * @param mark			optional mark for this SA
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_sa) (kernel_interface_t *this, host_t *src, host_t *dst,
+						u_int32_t spi, u_int8_t protocol, u_int16_t cpi,
+						mark_t mark);
+
+	/**
+	 * Flush all SAs from the SAD.
+	 *
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*flush_sas) (kernel_interface_t *this);
+
+	/**
+	 * Add a policy to the SPD.
+	 *
+	 * @param src			source address of SA
+	 * @param dst			dest address of SA
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param type			type of policy, POLICY_(IPSEC|PASS|DROP)
+	 * @param sa			details about the SA(s) tied to this policy
+	 * @param mark			mark for this policy
+	 * @param priority		priority of this policy
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_policy) (kernel_interface_t *this,
+							host_t *src, host_t *dst,
+							traffic_selector_t *src_ts,
+							traffic_selector_t *dst_ts,
+							policy_dir_t direction, policy_type_t type,
+							ipsec_sa_cfg_t *sa, mark_t mark,
+							policy_priority_t priority);
+
+	/**
+	 * Query the use time of a policy.
+	 *
+	 * The use time of a policy is the time the policy was used
+	 * for the last time.
+	 *
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param mark			optional mark
+	 * @param[out] use_time	the (monotonic) time of this SA's last use
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*query_policy) (kernel_interface_t *this,
+							  traffic_selector_t *src_ts,
+							  traffic_selector_t *dst_ts,
+							  policy_dir_t direction, mark_t mark,
+							  time_t *use_time);
+
+	/**
+	 * Remove a policy from the SPD.
+	 *
+	 * @param src			source address of SA
+	 * @param dst			dest address of SA
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param type			type of policy, POLICY_(IPSEC|PASS|DROP)
+	 * @param sa			details about the SA(s) tied to this policy
+	 * @param mark			mark for this policy
+	 * @param priority		priority of the policy
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_policy) (kernel_interface_t *this,
+							host_t *src, host_t *dst,
+							traffic_selector_t *src_ts,
+							traffic_selector_t *dst_ts,
+							policy_dir_t direction, policy_type_t type,
+							ipsec_sa_cfg_t *sa, mark_t mark,
+							policy_priority_t priority);
+
+	/**
+	 * Flush all policies from the SPD.
+	 *
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*flush_policies) (kernel_interface_t *this);
+
+	/**
+	 * Get our outgoing source address for a destination.
+	 *
+	 * Does a route lookup to get the source address used to reach dest.
+	 * The returned host is allocated and must be destroyed.
+	 * An optional src address can be used to check if a route is available
+	 * for the given source to dest.
+	 *
+	 * @param dest			target destination address
+	 * @param src			source address to check, or NULL
+	 * @return				outgoing source address, NULL if unreachable
+	 */
+	host_t* (*get_source_addr)(kernel_interface_t *this,
+							   host_t *dest, host_t *src);
+
+	/**
+	 * Get the next hop for a destination.
+	 *
+	 * Does a route lookup to get the next hop used to reach dest.
+	 * The returned host is allocated and must be destroyed.
+	 * An optional src address can be used to check if a route is available
+	 * for the given source to dest.
+	 *
+	 * @param dest			target destination address
+	 * @param prefix		prefix length if dest is a subnet, -1 for auto
+	 * @param src			source address to check, or NULL
+	 * @return				next hop address, NULL if unreachable
+	 */
+	host_t* (*get_nexthop)(kernel_interface_t *this, host_t *dest,
+						   int prefix, host_t *src);
+
+	/**
+	 * Get the interface name of a local address. Interfaces that are down or
+	 * ignored by config are not considered.
+	 *
+	 * @param host			address to get interface name from
+	 * @param name			allocated interface name (optional)
+	 * @return				TRUE if interface found and usable
+	 */
+	bool (*get_interface)(kernel_interface_t *this, host_t *host, char **name);
+
+	/**
+	 * Creates an enumerator over all local addresses.
+	 *
+	 * This function blocks an internal cached address list until the
+	 * enumerator gets destroyed.
+	 * The hosts are read-only, do not modify of free.
+	 *
+	 * @param which			a combination of address types to enumerate
+	 * @return				enumerator over host_t's
+	 */
+	enumerator_t *(*create_address_enumerator) (kernel_interface_t *this,
+												kernel_address_type_t which);
+
+	/**
+	 * Add a virtual IP to an interface.
+	 *
+	 * Virtual IPs are attached to an interface. If an IP is added multiple
+	 * times, the IP is refcounted and not removed until del_ip() was called
+	 * as many times as add_ip().
+	 *
+	 * @param virtual_ip	virtual ip address to assign
+	 * @param prefix		prefix length to install IP with, -1 for auto
+	 * @param iface			interface to install virtual IP on
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_ip) (kernel_interface_t *this, host_t *virtual_ip, int prefix,
+						char *iface);
+
+	/**
+	 * Remove a virtual IP from an interface.
+	 *
+	 * The kernel interface uses refcounting, see add_ip().
+	 *
+	 * @param virtual_ip	virtual ip address to remove
+	 * @param prefix		prefix length of the IP to uninstall, -1 for auto
+	 * @param wait			TRUE to wait untily IP is gone
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_ip) (kernel_interface_t *this, host_t *virtual_ip,
+						int prefix, bool wait);
+
+	/**
+	 * Add a route.
+	 *
+	 * @param dst_net		destination net
+	 * @param prefixlen		destination net prefix length
+	 * @param gateway		gateway for this route
+	 * @param src_ip		source ip of the route
+	 * @param if_name		name of the interface the route is bound to
+	 * @return				SUCCESS if operation completed
+	 *						ALREADY_DONE if the route already exists
+	 */
+	status_t (*add_route) (kernel_interface_t *this, chunk_t dst_net,
+						   u_int8_t prefixlen, host_t *gateway, host_t *src_ip,
+						   char *if_name);
+
+	/**
+	 * Delete a route.
+	 *
+	 * @param dst_net		destination net
+	 * @param prefixlen		destination net prefix length
+	 * @param gateway		gateway for this route
+	 * @param src_ip		source ip of the route
+	 * @param if_name		name of the interface the route is bound to
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_route) (kernel_interface_t *this, chunk_t dst_net,
+						   u_int8_t prefixlen, host_t *gateway, host_t *src_ip,
+						   char *if_name);
+
+	/**
+	 * Set up a bypass policy for a given socket.
+	 *
+	 * @param fd			socket file descriptor to setup policy for
+	 * @param family		protocol family of the socket
+	 * @return				TRUE if policy set up successfully
+	 */
+	bool (*bypass_socket)(kernel_interface_t *this, int fd, int family);
+
+	/**
+	 * Enable decapsulation of ESP-in-UDP packets for the given port/socket.
+	 *
+	 * @param fd			socket file descriptor
+	 * @param family		protocol family of the socket
+	 * @param port			the UDP port
+	 * @return				TRUE if UDP decapsulation was enabled successfully
+	 */
+	bool (*enable_udp_decap)(kernel_interface_t *this, int fd, int family,
+							 u_int16_t port);
+
+
+	/**
+	 * manager methods
+	 */
+
+	/**
+	 * Verifies that the given interface is usable and not excluded by
+	 * configuration.
+	 *
+	 * @param iface			interface name
+	 * @return				TRUE if usable
+	 */
+	bool (*is_interface_usable)(kernel_interface_t *this, const char *iface);
+
+	/**
+	 * Check if interfaces are excluded by config.
+	 *
+	 * @return				TRUE if no interfaces are exclued by config
+	 */
+	bool (*all_interfaces_usable)(kernel_interface_t *this);
+
+	/**
+	 * Tries to find an IP address of a local interface that is included in the
+	 * supplied traffic selector.
+	 *
+	 * @param ts			traffic selector
+	 * @param ip			returned IP address (has to be destroyed)
+	 * @param vip			set to TRUE if returned address is a virtual IP
+	 * @return				SUCCESS if address found
+	 */
+	status_t (*get_address_by_ts)(kernel_interface_t *this,
+								  traffic_selector_t *ts, host_t **ip, bool *vip);
+
+	/**
+	 * Register an ipsec kernel interface constructor on the manager.
+	 *
+	 * @param create		constructor to register
+	 * @return				TRUE if the ipsec kernel interface was registered
+	 *						successfully, FALSE if an interface was already
+	 *						registered or the registration failed
+	 */
+	bool (*add_ipsec_interface)(kernel_interface_t *this,
+								kernel_ipsec_constructor_t create);
+
+	/**
+	 * Unregister an ipsec kernel interface constructor.
+	 *
+	 * @param create		constructor to unregister
+	 * @return				TRUE if the ipsec kernel interface was unregistered
+	 *						successfully, FALSE otherwise
+	 */
+	bool (*remove_ipsec_interface)(kernel_interface_t *this,
+								   kernel_ipsec_constructor_t create);
+
+	/**
+	 * Register a network kernel interface constructor on the manager.
+	 *
+	 * @param create		constructor to register
+	 * @return				TRUE if the kernel net interface was registered
+	 *						successfully, FALSE if an interface was already
+	 *						registered or the registration failed
+	 */
+	bool (*add_net_interface)(kernel_interface_t *this,
+							  kernel_net_constructor_t create);
+
+	/**
+	 * Unregister a network kernel interface constructor.
+	 *
+	 * @param create		constructor to unregister
+	 * @return				TRUE if the kernel net interface was unregistered
+	 *						successfully, FALSE otherwise
+	 */
+	bool (*remove_net_interface)(kernel_interface_t *this,
+								 kernel_net_constructor_t create);
+
+	/**
+	 * Add a listener to the kernel interface.
+	 *
+	 * @param listener		listener to add
+	 */
+	void (*add_listener)(kernel_interface_t *this,
+						 kernel_listener_t *listener);
+
+	/**
+	 * Remove a listener from the kernel interface.
+	 *
+	 * @param listener		listener to remove
+	 */
+	void (*remove_listener)(kernel_interface_t *this,
+							kernel_listener_t *listener);
+
+	/**
+	 * Raise an acquire event.
+	 *
+	 * @param reqid			reqid of the policy to acquire
+	 * @param src_ts		source traffic selector
+	 * @param dst_ts		destination traffic selector
+	 */
+	void (*acquire)(kernel_interface_t *this, u_int32_t reqid,
+					traffic_selector_t *src_ts, traffic_selector_t *dst_ts);
+
+	/**
+	 * Raise an expire event.
+	 *
+	 * @param protocol		protocol of the expired SA
+	 * @param spi			spi of the expired SA
+	 * @param dst			destination address of expired SA
+	 * @param hard			TRUE if it is a hard expire, FALSE otherwise
+	 */
+	void (*expire)(kernel_interface_t *this, u_int8_t protocol, u_int32_t spi,
+				   host_t *dst, bool hard);
+
+	/**
+	 * Raise a mapping event.
+	 *
+	 * @param protocol		protocol of affected SA
+	 * @param spi			spi of the SA
+	 * @param dst			original destination address of SA
+	 * @param remote		new remote host
+	 */
+	void (*mapping)(kernel_interface_t *this, u_int8_t protocol, u_int32_t spi,
+					host_t *dst, host_t *remote);
+
+	/**
+	 * Raise a migrate event.
+	 *
+	 * @param reqid			reqid of the policy
+	 * @param src_ts		source traffic selector
+	 * @param dst_ts		destination traffic selector
+	 * @param direction		direction of the policy (in|out)
+	 * @param local			local host address to be used in the IKE_SA
+	 * @param remote		remote host address to be used in the IKE_SA
+	 */
+	void (*migrate)(kernel_interface_t *this, u_int32_t reqid,
+					traffic_selector_t *src_ts, traffic_selector_t *dst_ts,
+					policy_dir_t direction, host_t *local, host_t *remote);
+
+	/**
+	 * Raise a roam event.
+	 *
+	 * @param address		TRUE if address list, FALSE if routing changed
+	 */
+	void (*roam)(kernel_interface_t *this, bool address);
+
+	/**
+	 * Raise a tun event.
+	 *
+	 * @param tun			TUN device
+	 * @param created		TRUE if created, FALSE if going to be destroyed
+	 */
+	void (*tun)(kernel_interface_t *this, tun_device_t *tun, bool created);
+
+	/**
+	 * Register a new algorithm with the kernel interface.
+	 *
+	 * @param alg_id			the IKE id of the algorithm
+	 * @param type				the transform type of the algorithm
+	 * @param kernel_id			the kernel id of the algorithm
+	 * @param kernel_name		the kernel name of the algorithm
+	 */
+	void (*register_algorithm)(kernel_interface_t *this, u_int16_t alg_id,
+							   transform_type_t type, u_int16_t kernel_id,
+							   char *kernel_name);
+
+	/**
+	 * Return the kernel-specific id and/or name for an algorithms depending on
+	 * the arguments specified.
+	 *
+	 * @param alg_id			the IKE id of the algorithm
+	 * @param type				the transform type of the algorithm
+	 * @param kernel_id			the kernel id of the algorithm (optional)
+	 * @param kernel_name		the kernel name of the algorithm (optional)
+	 * @return					TRUE if algorithm was found
+	 */
+	bool (*lookup_algorithm)(kernel_interface_t *this, u_int16_t alg_id,
+							 transform_type_t type, u_int16_t *kernel_id,
+							 char **kernel_name);
+
+	/**
+	 * Destroys a kernel_interface_t object.
+	 */
+	void (*destroy) (kernel_interface_t *this);
+};
+
+/**
+ * Creates an object of type kernel_interface_t.
+ */
+kernel_interface_t *kernel_interface_create(void);
+
+#endif /** KERNEL_INTERFACE_H_ @}*/

src/libcharon/kernel/kernel_ipsec.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include "kernel_ipsec.h"
+
+#include <daemon.h>
+
+/**
+ * See header
+ */
+bool kernel_ipsec_register(plugin_t *plugin, plugin_feature_t *feature,
+						   bool reg, void *data)
+{
+	if (reg)
+	{
+		return charon->kernel->add_ipsec_interface(charon->kernel,
+											(kernel_ipsec_constructor_t)data);
+	}
+	else
+	{
+		return charon->kernel->remove_ipsec_interface(charon->kernel,
+											(kernel_ipsec_constructor_t)data);
+	}
+}

src/libcharon/kernel/kernel_ipsec.h

@@ -0,0 +1,297 @@
+/*
+ * Copyright (C) 2006-2015 Tobias Brunner
+ * Copyright (C) 2006 Daniel Roethlisberger
+ * Copyright (C) 2005-2006 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup kernel_ipsec kernel_ipsec
+ * @{ @ingroup kernel
+ */
+
+#ifndef KERNEL_IPSEC_H_
+#define KERNEL_IPSEC_H_
+
+typedef struct kernel_ipsec_t kernel_ipsec_t;
+
+#include <networking/host.h>
+#include <ipsec/ipsec_types.h>
+#include <selectors/traffic_selector.h>
+#include <plugins/plugin.h>
+#include <kernel/kernel_interface.h>
+
+/**
+ * Interface to the ipsec subsystem of the kernel.
+ *
+ * The kernel ipsec interface handles the communication with the kernel
+ * for SA and policy management. It allows setup of these, and provides
+ * further the handling of kernel events.
+ * Policy information are cached in the interface. This is necessary to do
+ * reference counting. The Linux kernel does not allow the same policy
+ * installed twice, but we need this as CHILD_SA exist multiple times
+ * when rekeying. Thats why we do reference counting of policies.
+ */
+struct kernel_ipsec_t {
+
+	/**
+	 * Get the feature set supported by this kernel backend.
+	 *
+	 * @return				ORed feature-set of backend
+	 */
+	kernel_feature_t (*get_features)(kernel_ipsec_t *this);
+
+	/**
+	 * Get a SPI from the kernel.
+	 *
+	 * @param src		source address of SA
+	 * @param dst		destination address of SA
+	 * @param protocol	protocol for SA (ESP/AH)
+	 * @param spi		allocated spi
+	 * @return			SUCCESS if operation completed
+	 */
+	status_t (*get_spi)(kernel_ipsec_t *this, host_t *src, host_t *dst,
+						u_int8_t protocol, u_int32_t *spi);
+
+	/**
+	 * Get a Compression Parameter Index (CPI) from the kernel.
+	 *
+	 * @param src		source address of SA
+	 * @param dst		destination address of SA
+	 * @param cpi		allocated cpi
+	 * @return			SUCCESS if operation completed
+	 */
+	status_t (*get_cpi)(kernel_ipsec_t *this, host_t *src, host_t *dst,
+						u_int16_t *cpi);
+
+	/**
+	 * Add an SA to the SAD.
+	 *
+	 * This function does install a single SA for a single protocol in one
+	 * direction.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param reqid			unique ID for this SA
+	 * @param mark			mark for this SA
+	 * @param tfc			Traffic Flow Confidentiality padding for this SA
+	 * @param lifetime		lifetime_cfg_t for this SA
+	 * @param enc_alg		Algorithm to use for encryption (ESP only)
+	 * @param enc_key		key to use for encryption
+	 * @param int_alg		Algorithm to use for integrity protection
+	 * @param int_key		key to use for integrity protection
+	 * @param mode			mode of the SA (tunnel, transport)
+	 * @param ipcomp		IPComp transform to use
+	 * @param cpi			CPI for IPComp
+	 * @param replay_window	anti-replay window size
+	 * @param initiator		TRUE if initiator of the exchange creating this SA
+	 * @param encap			enable UDP encapsulation for NAT traversal
+	 * @param esn			TRUE to use Extended Sequence Numbers
+	 * @param inbound		TRUE if this is an inbound SA
+	 * @param update		TRUE if an SPI has already been allocated for SA
+	 * @param src_ts		list of source traffic selectors
+	 * @param dst_ts		list of destination traffic selectors
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_sa) (kernel_ipsec_t *this,
+						host_t *src, host_t *dst, u_int32_t spi,
+						u_int8_t protocol, u_int32_t reqid,
+						mark_t mark, u_int32_t tfc, lifetime_cfg_t *lifetime,
+						u_int16_t enc_alg, chunk_t enc_key,
+						u_int16_t int_alg, chunk_t int_key,
+						ipsec_mode_t mode, u_int16_t ipcomp, u_int16_t cpi,
+						u_int32_t replay_window, bool initiator, bool encap,
+						bool esn, bool inbound, bool update,
+						linked_list_t *src_ts, linked_list_t *dst_ts);
+
+	/**
+	 * Update the hosts on an installed SA.
+	 *
+	 * We cannot directly update the destination address as the kernel
+	 * requires the spi, the protocol AND the destination address (and family)
+	 * to identify SAs. Therefore if the destination address changed we
+	 * create a new SA and delete the old one.
+	 *
+	 * @param spi			SPI of the SA
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param cpi			CPI for IPComp, 0 if no IPComp is used
+	 * @param src			current source address
+	 * @param dst			current destination address
+	 * @param new_src		new source address
+	 * @param new_dst		new destination address
+	 * @param encap			current use of UDP encapsulation
+	 * @param new_encap		new use of UDP encapsulation
+	 * @param mark			optional mark for this SA
+	 * @return				SUCCESS if operation completed, NOT_SUPPORTED if
+	 *					  the kernel interface can't update the SA
+	 */
+	status_t (*update_sa)(kernel_ipsec_t *this,
+						  u_int32_t spi, u_int8_t protocol, u_int16_t cpi,
+						  host_t *src, host_t *dst,
+						  host_t *new_src, host_t *new_dst,
+						  bool encap, bool new_encap, mark_t mark);
+
+	/**
+	 * Query the number of bytes processed by an SA from the SAD.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param mark			optional mark for this SA
+	 * @param[out] bytes	the number of bytes processed by SA
+	 * @param[out] packets	number of packets processed by SA
+	 * @param[out] time		last (monotonic) time of SA use
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*query_sa) (kernel_ipsec_t *this, host_t *src, host_t *dst,
+						  u_int32_t spi, u_int8_t protocol, mark_t mark,
+						  u_int64_t *bytes, u_int64_t *packets, time_t *time);
+
+	/**
+	 * Delete a previusly installed SA from the SAD.
+	 *
+	 * @param src			source address for this SA
+	 * @param dst			destination address for this SA
+	 * @param spi			SPI allocated by us or remote peer
+	 * @param protocol		protocol for this SA (ESP/AH)
+	 * @param cpi			CPI for IPComp or 0
+	 * @param mark			optional mark for this SA
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_sa) (kernel_ipsec_t *this, host_t *src, host_t *dst,
+						u_int32_t spi, u_int8_t protocol, u_int16_t cpi,
+						mark_t mark);
+
+	/**
+	 * Flush all SAs from the SAD.
+	 *
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*flush_sas) (kernel_ipsec_t *this);
+
+	/**
+	 * Add a policy to the SPD.
+	 *
+	 * @param src			source address of SA
+	 * @param dst			dest address of SA
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param type			type of policy, POLICY_(IPSEC|PASS|DROP)
+	 * @param sa			details about the SA(s) tied to this policy
+	 * @param mark			mark for this policy
+	 * @param priority		priority of this policy
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_policy) (kernel_ipsec_t *this,
+							host_t *src, host_t *dst,
+							traffic_selector_t *src_ts,
+							traffic_selector_t *dst_ts,
+							policy_dir_t direction, policy_type_t type,
+							ipsec_sa_cfg_t *sa, mark_t mark,
+							policy_priority_t priority);
+
+	/**
+	 * Query the use time of a policy.
+	 *
+	 * The use time of a policy is the time the policy was used for the last
+	 * time. It is not the system time, but a monotonic timestamp as returned
+	 * by time_monotonic.
+	 *
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param mark			optional mark
+	 * @param[out] use_time	the monotonic timestamp of this SA's last use
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*query_policy) (kernel_ipsec_t *this,
+							  traffic_selector_t *src_ts,
+							  traffic_selector_t *dst_ts,
+							  policy_dir_t direction, mark_t mark,
+							  time_t *use_time);
+
+	/**
+	 * Remove a policy from the SPD.
+	 *
+	 * @param src			source address of SA
+	 * @param dst			dest address of SA
+	 * @param src_ts		traffic selector to match traffic source
+	 * @param dst_ts		traffic selector to match traffic dest
+	 * @param direction		direction of traffic, POLICY_(IN|OUT|FWD)
+	 * @param type			type of policy, POLICY_(IPSEC|PASS|DROP)
+	 * @param sa			details about the SA(s) tied to this policy
+	 * @param mark			mark for this policy
+	 * @param priority		priority of the policy
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_policy) (kernel_ipsec_t *this,
+							host_t *src, host_t *dst,
+							traffic_selector_t *src_ts,
+							traffic_selector_t *dst_ts,
+							policy_dir_t direction, policy_type_t type,
+							ipsec_sa_cfg_t *sa, mark_t mark,
+							policy_priority_t priority);
+
+	/**
+	 * Flush all policies from the SPD.
+	 *
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*flush_policies) (kernel_ipsec_t *this);
+
+	/**
+	 * Install a bypass policy for the given socket.
+	 *
+	 * @param fd			socket file descriptor to setup policy for
+	 * @param family		protocol family of the socket
+	 * @return				TRUE of policy set up successfully
+	 */
+	bool (*bypass_socket)(kernel_ipsec_t *this, int fd, int family);
+
+	/**
+	 * Enable decapsulation of ESP-in-UDP packets for the given port/socket.
+	 *
+	 * @param fd			socket file descriptor
+	 * @param family		protocol family of the socket
+	 * @param port			the UDP port
+	 * @return				TRUE if UDP decapsulation was enabled successfully
+	 */
+	bool (*enable_udp_decap)(kernel_ipsec_t *this, int fd, int family,
+							 u_int16_t port);
+
+	/**
+	 * Destroy the implementation.
+	 */
+	void (*destroy) (kernel_ipsec_t *this);
+};
+
+/**
+ * Helper function to (un-)register IPsec kernel interfaces from plugin features.
+ *
+ * This function is a plugin_feature_callback_t and can be used with the
+ * PLUGIN_CALLBACK macro to register an IPsec kernel interface constructor.
+ *
+ * @param plugin		plugin registering the kernel interface
+ * @param feature		associated plugin feature
+ * @param reg			TRUE to register, FALSE to unregister
+ * @param data			data passed to callback, an kernel_ipsec_constructor_t
+ */
+bool kernel_ipsec_register(plugin_t *plugin, plugin_feature_t *feature,
+						   bool reg, void *data);
+
+#endif /** KERNEL_IPSEC_H_ @}*/

src/libcharon/kernel/kernel_listener.h

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2010-2013 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup kernel_listener kernel_listener
+ * @{ @ingroup kernel
+ */
+
+#ifndef KERNEL_LISTENER_H_
+#define KERNEL_LISTENER_H_
+
+typedef struct kernel_listener_t kernel_listener_t;
+
+#include <networking/host.h>
+#include <networking/tun_device.h>
+#include <selectors/traffic_selector.h>
+#include <kernel/kernel_ipsec.h>
+
+/**
+ * Interface for components interested in kernel events.
+ *
+ * All hooks are optional.
+ */
+struct kernel_listener_t {
+
+	/**
+	 * Hook called if an acquire event for a policy is received.
+	 *
+	 * @param reqid			reqid of the policy to acquire
+	 * @param src_ts		source traffic selector
+	 * @param dst_ts		destination traffic selector
+	 * @return				TRUE to remain registered, FALSE to unregister
+	 */
+	bool (*acquire)(kernel_listener_t *this, u_int32_t reqid,
+					traffic_selector_t *src_ts, traffic_selector_t *dst_ts);
+
+	/**
+	 * Hook called if an exire event for an IPsec SA is received.
+	 *
+	 * @param protocol		protocol of the expired SA
+	 * @param spi			spi of the expired SA
+	 * @param dst			destination address of expired SA
+	 * @param hard			TRUE if it is a hard expire, FALSE otherwise
+	 * @return				TRUE to remain registered, FALSE to unregister
+	 */
+	bool (*expire)(kernel_listener_t *this, u_int8_t protocol, u_int32_t spi,
+				   host_t *dst, bool hard);
+
+	/**
+	 * Hook called if the NAT mappings of an IPsec SA changed.
+	 *
+	 * @param protocol		IPsec protocol of affected SA
+	 * @param spi			spi of the SA
+	 * @param dst			old destinatino address of SA
+	 * @param remote		new remote host
+	 * @return				TRUE to remain registered, FALSE to unregister
+	 */
+	bool (*mapping)(kernel_listener_t *this, u_int8_t protocol, u_int32_t spi,
+					host_t *dst, host_t *remote);
+
+	/**
+	 * Hook called if a migrate event for a policy is received.
+	 *
+	 * @param reqid			reqid of the policy
+	 * @param src_ts		source traffic selector
+	 * @param dst_ts		destination traffic selector
+	 * @param direction		direction of the policy (in|out)
+	 * @param local			local host address to be used in the IKE_SA
+	 * @param remote		remote host address to be used in the IKE_SA
+	 * @return				TRUE to remain registered, FALSE to unregister
+	 */
+	bool (*migrate)(kernel_listener_t *this, u_int32_t reqid,
+					traffic_selector_t *src_ts, traffic_selector_t *dst_ts,
+					policy_dir_t direction, host_t *local, host_t *remote);
+
+	/**
+	 * Hook called if changes in the networking layer occurred (interfaces
+	 * up/down, routes added/deleted etc.).
+	 *
+	 * @param address		TRUE if address list, FALSE if routing changed
+	 * @return				TRUE to remain registered, FALSE to unregister
+	 */
+	bool (*roam)(kernel_listener_t *this, bool address);
+
+	/**
+	 * Hook called after a TUN device was created for a virtual IP address, or
+	 * before such a device gets destroyed.
+	 *
+	 * @param tun			TUN device
+	 * @param created		TRUE if created, FALSE if going to be destroyed
+	 */
+	bool (*tun)(kernel_listener_t *this, tun_device_t *tun, bool created);
+};
+
+#endif /** KERNEL_LISTENER_H_ @}*/

src/libcharon/kernel/kernel_net.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2011 Martin Willi
+ * Copyright (C) 2011 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include "kernel_net.h"
+
+#include <daemon.h>
+
+/**
+ * See header
+ */
+bool kernel_net_register(plugin_t *plugin, plugin_feature_t *feature,
+						 bool reg, void *data)
+{
+	if (reg)
+	{
+		return charon->kernel->add_net_interface(charon->kernel,
+											(kernel_net_constructor_t)data);
+	}
+	else
+	{
+		return charon->kernel->remove_net_interface(charon->kernel,
+											(kernel_net_constructor_t)data);
+	}
+}

src/libcharon/kernel/kernel_net.h

@@ -0,0 +1,196 @@
+/*
+ * Copyright (C) 2008-2012 Tobias Brunner
+ * Copyright (C) 2007 Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup kernel_net kernel_net
+ * @{ @ingroup kernel
+ */
+
+#ifndef KERNEL_NET_H_
+#define KERNEL_NET_H_
+
+typedef struct kernel_net_t kernel_net_t;
+typedef enum kernel_address_type_t kernel_address_type_t;
+
+#include <collections/enumerator.h>
+#include <networking/host.h>
+#include <plugins/plugin.h>
+#include <kernel/kernel_interface.h>
+
+/**
+ * Type of addresses (e.g. when enumerating them)
+ */
+enum kernel_address_type_t {
+	/** normal addresses (on regular, up, non-ignored) interfaces */
+	ADDR_TYPE_REGULAR = (1 << 0),
+	/** addresses on down interfaces */
+	ADDR_TYPE_DOWN =  (1 << 1),
+	/** addresses on ignored interfaces */
+	ADDR_TYPE_IGNORED = (1 << 2),
+	/** addresses on loopback interfaces */
+	ADDR_TYPE_LOOPBACK = (1 << 3),
+	/** virtual IP addresses */
+	ADDR_TYPE_VIRTUAL = (1 << 4),
+	/** to enumerate all available addresses */
+	ADDR_TYPE_ALL = (1 << 5) - 1,
+};
+
+/**
+ * Interface to the network subsystem of the kernel.
+ *
+ * The kernel network interface handles the communication with the kernel
+ * for interface and IP address management.
+ */
+struct kernel_net_t {
+
+	/**
+	 * Get the feature set supported by this kernel backend.
+	 *
+	 * @return				ORed feature-set of backend
+	 */
+	kernel_feature_t (*get_features)(kernel_net_t *this);
+
+	/**
+	 * Get our outgoing source address for a destination.
+	 *
+	 * Does a route lookup to get the source address used to reach dest.
+	 * The returned host is allocated and must be destroyed.
+	 * An optional src address can be used to check if a route is available
+	 * for the given source to dest.
+	 *
+	 * @param dest			target destination address
+	 * @param src			source address to check, or NULL
+	 * @return				outgoing source address, NULL if unreachable
+	 */
+	host_t* (*get_source_addr)(kernel_net_t *this, host_t *dest, host_t *src);
+
+	/**
+	 * Get the next hop for a destination.
+	 *
+	 * Does a route lookup to get the next hop used to reach dest.
+	 * The returned host is allocated and must be destroyed.
+	 * An optional src address can be used to check if a route is available
+	 * for the given source to dest.
+	 *
+	 * @param dest			target destination address
+	 * @param prefix		prefix length if dest is a subnet, -1 for auto
+	 * @param src			source address to check, or NULL
+	 * @return				next hop address, NULL if unreachable
+	 */
+	host_t* (*get_nexthop)(kernel_net_t *this, host_t *dest, int prefix,
+						   host_t *src);
+
+	/**
+	 * Get the interface name of a local address. Interfaces that are down or
+	 * ignored by config are not considered.
+	 *
+	 * @param host			address to get interface name from
+	 * @param name			allocated interface name (optional)
+	 * @return				TRUE if interface found and usable
+	 */
+	bool (*get_interface) (kernel_net_t *this, host_t *host, char **name);
+
+	/**
+	 * Creates an enumerator over all local addresses.
+	 *
+	 * This function blocks an internal cached address list until the
+	 * enumerator gets destroyed.
+	 * The hosts are read-only, do not modify of free.
+	 *
+	 * @param which			a combination of address types to enumerate
+	 * @return				enumerator over host_t's
+	 */
+	enumerator_t *(*create_address_enumerator) (kernel_net_t *this,
+												kernel_address_type_t which);
+
+	/**
+	 * Add a virtual IP to an interface.
+	 *
+	 * Virtual IPs are attached to an interface. If an IP is added multiple
+	 * times, the IP is refcounted and not removed until del_ip() was called
+	 * as many times as add_ip().
+	 *
+	 * @param virtual_ip	virtual ip address to assign
+	 * @param prefix		prefix length to install with IP address, -1 for auto
+	 * @param iface			interface to install virtual IP on
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*add_ip) (kernel_net_t *this, host_t *virtual_ip, int prefix,
+						char *iface);
+
+	/**
+	 * Remove a virtual IP from an interface.
+	 *
+	 * The kernel interface uses refcounting, see add_ip().
+	 *
+	 * @param virtual_ip	virtual ip address to remove
+	 * @param prefix		prefix length of the IP to uninstall, -1 for auto
+	 * @param wait			TRUE to wait until IP is gone
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_ip) (kernel_net_t *this, host_t *virtual_ip, int prefix,
+						bool wait);
+
+	/**
+	 * Add a route.
+	 *
+	 * @param dst_net		destination net
+	 * @param prefixlen		destination net prefix length
+	 * @param gateway		gateway for this route
+	 * @param src_ip		source ip of the route
+	 * @param if_name		name of the interface the route is bound to
+	 * @return				SUCCESS if operation completed
+	 *						ALREADY_DONE if the route already exists
+	 */
+	status_t (*add_route) (kernel_net_t *this, chunk_t dst_net,
+						   u_int8_t prefixlen, host_t *gateway, host_t *src_ip,
+						   char *if_name);
+
+	/**
+	 * Delete a route.
+	 *
+	 * @param dst_net		destination net
+	 * @param prefixlen		destination net prefix length
+	 * @param gateway		gateway for this route
+	 * @param src_ip		source ip of the route
+	 * @param if_name		name of the interface the route is bound to
+	 * @return				SUCCESS if operation completed
+	 */
+	status_t (*del_route) (kernel_net_t *this, chunk_t dst_net,
+						   u_int8_t prefixlen, host_t *gateway, host_t *src_ip,
+						   char *if_name);
+
+	/**
+	 * Destroy the implementation.
+	 */
+	void (*destroy) (kernel_net_t *this);
+};
+
+/**
+ * Helper function to (un-)register net kernel interfaces from plugin features.
+ *
+ * This function is a plugin_feature_callback_t and can be used with the
+ * PLUGIN_CALLBACK macro to register an net kernel interface constructor.
+ *
+ * @param plugin		plugin registering the kernel interface
+ * @param feature		associated plugin feature
+ * @param reg			TRUE to register, FALSE to unregister
+ * @param data			data passed to callback, an kernel_net_constructor_t
+ */
+bool kernel_net_register(plugin_t *plugin, plugin_feature_t *feature,
+						 bool reg, void *data);
+
+#endif /** KERNEL_NET_H_ @}*/