Extracted in-memory IP address pool from stroke plugin to libhydra.

5 files changed, 584 insertions, 352 deletions

diff --git a/src/libcharon/plugins/stroke/stroke_attribute.c b/src/libcharon/plugins/stroke/stroke_attribute.c
index 7a5ce683e..0ee45746e 100644
--- a/src/libcharon/plugins/stroke/stroke_attribute.c
+++ b/src/libcharon/plugins/stroke/stroke_attribute.c
@@ -16,12 +16,10 @@
 #include "stroke_attribute.h"
 
 #include <daemon.h>
+#include <attributes/mem_pool.h>
 #include <utils/linked_list.h>
-#include <utils/hashtable.h>
 #include <threading/mutex.h>
 
-#define POOL_LIMIT (sizeof(uintptr_t)*8)
-
 typedef struct private_stroke_attribute_t private_stroke_attribute_t;
 
 /**
@@ -35,7 +33,7 @@ struct private_stroke_attribute_t {
 	stroke_attribute_t public;
 
 	/**
-	 * list of pools, contains pool_t
+	 * list of pools, contains mem_pool_t
 	 */
 	linked_list_t *pools;
 
@@ -45,73 +43,18 @@ struct private_stroke_attribute_t {
 	mutex_t *mutex;
 };
 
-typedef struct {
-	/** name of the pool */
-	char *name;
-	/** base address of the pool */
-	host_t *base;
-	/** size of the pool */
-	int size;
-	/** next unused address */
-	int unused;
-	/** hashtable [identity => offset], for online leases */
-	hashtable_t *online;
-	/** hashtable [identity => offset], for offline leases */
-	hashtable_t *offline;
-	/** hashtable [identity => identity], handles identity references */
-	hashtable_t *ids;
-} pool_t;
-
-/**
- * hashtable hash function for identities
- */
-static u_int id_hash(identification_t *id)
-{
-	return chunk_hash(id->get_encoding(id));
-}
-
-/**
- * hashtable equals function for identities
- */
-static bool id_equals(identification_t *a, identification_t *b)
-{
-	return a->equals(a, b);
-}
-
-/**
- * destroy a pool_t
- */
-static void pool_destroy(pool_t *this)
-{
-	enumerator_t *enumerator;
-	identification_t *id;
-
-	enumerator = this->ids->create_enumerator(this->ids);
-	while (enumerator->enumerate(enumerator, &id, NULL))
-	{
-		id->destroy(id);
-	}
-	enumerator->destroy(enumerator);
-	this->ids->destroy(this->ids);
-	this->online->destroy(this->online);
-	this->offline->destroy(this->offline);
-	DESTROY_IF(this->base);
-	free(this->name);
-	free(this);
-}
-
 /**
  * find a pool by name
  */
-static pool_t *find_pool(private_stroke_attribute_t *this, char *name)
+static mem_pool_t *find_pool(private_stroke_attribute_t *this, char *name)
 {
 	enumerator_t *enumerator;
-	pool_t *current, *found = NULL;
+	mem_pool_t *current, *found = NULL;
 
 	enumerator = this->pools->create_enumerator(this->pools);
 	while (enumerator->enumerate(enumerator, &current))
 	{
-		if (streq(name, current->name))
+		if (streq(name, current->get_name(current)))
 		{
 			found = current;
 			break;
@@ -122,164 +65,22 @@ static pool_t *find_pool(private_stroke_attribute_t *this, char *name)
 }
 
 /**
- * convert an pool offset to an address
- */
-host_t* offset2host(pool_t *pool, int offset)
-{
-	chunk_t addr;
-	host_t *host;
-	u_int32_t *pos;
-
-	offset--;
-	if (offset > pool->size)
-	{
-		return NULL;
-	}
-
-	addr = chunk_clone(pool->base->get_address(pool->base));
-	if (pool->base->get_family(pool->base) == AF_INET6)
-	{
-		pos = (u_int32_t*)(addr.ptr + 12);
-	}
-	else
-	{
-		pos = (u_int32_t*)addr.ptr;
-	}
-	*pos = htonl(offset + ntohl(*pos));
-	host = host_create_from_chunk(pool->base->get_family(pool->base), addr, 0);
-	free(addr.ptr);
-	return host;
-}
-
-/**
- * convert a host to a pool offset
- */
-int host2offset(pool_t *pool, host_t *addr)
-{
-	chunk_t host, base;
-	u_int32_t hosti, basei;
-
-	if (addr->get_family(addr) != pool->base->get_family(pool->base))
-	{
-		return -1;
-	}
-	host = addr->get_address(addr);
-	base = pool->base->get_address(pool->base);
-	if (addr->get_family(addr) == AF_INET6)
-	{
-		/* only look at last /32 block */
-		if (!memeq(host.ptr, base.ptr, 12))
-		{
-			return -1;
-		}
-		host = chunk_skip(host, 12);
-		base = chunk_skip(base, 12);
-	}
-	hosti = ntohl(*(u_int32_t*)(host.ptr));
-	basei = ntohl(*(u_int32_t*)(base.ptr));
-	if (hosti > basei + pool->size)
-	{
-		return -1;
-	}
-	return hosti - basei + 1;
-}
-
-/**
  * Implementation of attribute_provider_t.acquire_address
  */
 static host_t* acquire_address(private_stroke_attribute_t *this,
 							   char *name, identification_t *id,
 							   host_t *requested)
 {
-	pool_t *pool;
-	uintptr_t offset = 0;
-	enumerator_t *enumerator;
-	identification_t *old_id;
-
+	mem_pool_t *pool;
+	host_t *addr = NULL;
 	this->mutex->lock(this->mutex);
 	pool = find_pool(this, name);
-	while (pool)
+	if (pool)
 	{
-		/* handle %config case by mirroring requested address */
-		if (pool->size == 0)
-		{
-			this->mutex->unlock(this->mutex);
-			return requested->clone(requested);
-		}
-
-		if (!requested->is_anyaddr(requested) &&
-			requested->get_family(requested) !=
-			pool->base->get_family(pool->base))
-		{
-			DBG1(DBG_CFG, "IP pool address family mismatch");
-			break;
-		}
-
-		/* check for a valid offline lease, refresh */
-		offset = (uintptr_t)pool->offline->remove(pool->offline, id);
-		if (offset)
-		{
-			id = pool->ids->get(pool->ids, id);
-			if (id)
-			{
-				DBG1(DBG_CFG, "reassigning offline lease to '%Y'", id);
-				pool->online->put(pool->online, id, (void*)offset);
-				break;
-			}
-		}
-
-		/* check for a valid online lease, reassign */
-		offset = (uintptr_t)pool->online->get(pool->online, id);
-		if (offset && offset == host2offset(pool, requested))
-		{
-			DBG1(DBG_CFG, "reassigning online lease to '%Y'", id);
-			break;
-		}
-
-		if (pool->unused < pool->size)
-		{
-			/* assigning offset, starting by 1. Handling 0 in hashtable
-			 * is difficult. */
-			offset = ++pool->unused;
-			id = id->clone(id);
-			pool->ids->put(pool->ids, id, id);
-			pool->online->put(pool->online, id, (void*)offset);
-			DBG1(DBG_CFG, "assigning new lease to '%Y'", id);
-			break;
-		}
-		/* no more addresses, replace the first found offline lease */
-		enumerator = pool->offline->create_enumerator(pool->offline);
-		if (enumerator->enumerate(enumerator, &old_id, &offset))
-		{
-			offset = (uintptr_t)pool->offline->remove(pool->offline, old_id);
-			if (offset)
-			{
-				/* destroy reference to old ID */
-				old_id = pool->ids->remove(pool->ids, old_id);
-				DBG1(DBG_CFG, "reassigning existing offline lease by '%Y' to '%Y'",
-					 old_id, id);
-				if (old_id)
-				{
-					old_id->destroy(old_id);
-				}
-				id = id->clone(id);
-				pool->ids->put(pool->ids, id, id);
-				pool->online->put(pool->online, id, (void*)offset);
-				enumerator->destroy(enumerator);
-				break;
-			}
-		}
-		enumerator->destroy(enumerator);
-
-		DBG1(DBG_CFG, "pool '%s' is full, unable to assign address", name);
-		break;
+		addr = pool->acquire_address(pool, id, requested);
 	}
 	this->mutex->unlock(this->mutex);
-	if (offset)
-	{
-		return offset2host(pool, offset);
-	}
-	return NULL;
+	return addr;
 }
 
 /**
@@ -288,28 +89,13 @@ static host_t* acquire_address(private_stroke_attribute_t *this,
 static bool release_address(private_stroke_attribute_t *this,
 							char *name, host_t *address, identification_t *id)
 {
-	pool_t *pool;
+	mem_pool_t *pool;
 	bool found = FALSE;
-	uintptr_t offset;
-
 	this->mutex->lock(this->mutex);
 	pool = find_pool(this, name);
 	if (pool)
 	{
-		if (pool->size != 0)
-		{
-			offset = (uintptr_t)pool->online->remove(pool->online, id);
-			if (offset)
-			{
-				id = pool->ids->get(pool->ids, id);
-				if (id)
-				{
-					DBG1(DBG_CFG, "lease %H by '%Y' went offline", address, id);
-					pool->offline->put(pool->offline, id, (void*)offset);
-					found = TRUE;
-				}
-			}
-		}
+		found = pool->release_address(pool, address, id);
 	}
 	this->mutex->unlock(this->mutex);
 	return found;
@@ -322,54 +108,27 @@ static void add_pool(private_stroke_attribute_t *this, stroke_msg_t *msg)
 {
 	if (msg->add_conn.other.sourceip_mask)
 	{
-		pool_t *pool;
-
-		pool = malloc_thing(pool_t);
-		pool->base = NULL;
-		pool->size = 0;
-		pool->unused = 0;
-		pool->name = strdup(msg->add_conn.name);
-		pool->online = hashtable_create((hashtable_hash_t)id_hash,
-										(hashtable_equals_t)id_equals, 16);
-		pool->offline = hashtable_create((hashtable_hash_t)id_hash,
-										(hashtable_equals_t)id_equals, 16);
-		pool->ids = hashtable_create((hashtable_hash_t)id_hash,
-										(hashtable_equals_t)id_equals, 16);
+		mem_pool_t *pool;
+		host_t *base = NULL;
+		u_int32_t bits = 0;
 
 		/* if %config, add an empty pool, otherwise */
 		if (msg->add_conn.other.sourceip)
 		{
-			u_int32_t bits;
-			int family;
-
 			DBG1(DBG_CFG, "adding virtual IP address pool '%s': %s/%d",
 				 msg->add_conn.name, msg->add_conn.other.sourceip,
 				 msg->add_conn.other.sourceip_mask);
-
-			pool->base = host_create_from_string(msg->add_conn.other.sourceip, 0);
-			if (!pool->base)
+			base = host_create_from_string(msg->add_conn.other.sourceip, 0);
+			if (!base)
 			{
-				pool_destroy(pool);
 				DBG1(DBG_CFG, "virtual IP address invalid, discarded");
 				return;
 			}
-			family = pool->base->get_family(pool->base);
-			bits = (family == AF_INET ? 32 : 128) - msg->add_conn.other.sourceip_mask;
-			if (bits > POOL_LIMIT)
-			{
-				bits = POOL_LIMIT;
-				DBG1(DBG_CFG, "virtual IP pool to large, limiting to %s/%d",
-					 msg->add_conn.other.sourceip,
-					 (family == AF_INET ? 32 : 128) - bits);
-			}
-			pool->size = 1 << (bits);
-
-			if (pool->size > 2)
-			{	/* do not use first and last addresses of a block */
-				pool->unused++;
-				pool->size--;
-			}
+			bits = msg->add_conn.other.sourceip_mask;
 		}
+		pool = mem_pool_create(msg->add_conn.name, base, bits);
+		DESTROY_IF(base);
+
 		this->mutex->lock(this->mutex);
 		this->pools->insert_last(this->pools, pool);
 		this->mutex->unlock(this->mutex);
@@ -382,16 +141,16 @@ static void add_pool(private_stroke_attribute_t *this, stroke_msg_t *msg)
 static void del_pool(private_stroke_attribute_t *this, stroke_msg_t *msg)
 {
 	enumerator_t *enumerator;
-	pool_t *pool;
+	mem_pool_t *pool;
 
 	this->mutex->lock(this->mutex);
 	enumerator = this->pools->create_enumerator(this->pools);
 	while (enumerator->enumerate(enumerator, &pool))
 	{
-		if (streq(msg->del_conn.name, pool->name))
+		if (streq(msg->del_conn.name, pool->get_name(pool)))
 		{
 			this->pools->remove_at(this->pools, enumerator);
-			pool_destroy(pool);
+			pool->destroy(pool);
 			break;
 		}
 	}
@@ -402,16 +161,15 @@ static void del_pool(private_stroke_attribute_t *this, stroke_msg_t *msg)
 /**
  * Pool enumerator filter function, converts pool_t to name, size, ...
  */
-static bool pool_filter(void *mutex, pool_t **poolp, char **name,
+static bool pool_filter(void *mutex, mem_pool_t **poolp, const char **name,
 						void *d1, u_int *size, void *d2, u_int *online,
 						void *d3, u_int *offline)
 {
-	pool_t *pool = *poolp;
-
-	*name = pool->name;
-	*size = pool->size;
-	*online = pool->online->get_count(pool->online);
-	*offline = pool->offline->get_count(pool->offline);
+	mem_pool_t *pool = *poolp;
+	*name = pool->get_name(pool);
+	*size = pool->get_size(pool);
+	*online = pool->get_online(pool);
+	*offline = pool->get_offline(pool);
 	return TRUE;
 }
 
@@ -427,89 +185,21 @@ static enumerator_t* create_pool_enumerator(private_stroke_attribute_t *this)
 }
 
 /**
- * lease enumerator
- */
-typedef struct {
-	/** implemented enumerator interface */
-	enumerator_t public;
-	/** inner hash-table enumerator */
-	enumerator_t *inner;
-	/** enumerated pool */
-	pool_t *pool;
-	/** mutex to unlock on destruction */
-	mutex_t *mutex;
-	/** currently enumerated lease address */
-	host_t *current;
-} lease_enumerator_t;
-
-/**
- * Implementation of lease_enumerator_t.enumerate
- */
-static bool lease_enumerate(lease_enumerator_t *this, identification_t **id_out,
-							host_t **addr_out, bool *online)
-{
-	identification_t *id;
-	uintptr_t offset;
-
-	DESTROY_IF(this->current);
-	this->current = NULL;
-
-	if (this->inner->enumerate(this->inner, &id, NULL))
-	{
-		offset = (uintptr_t)this->pool->online->get(this->pool->online, id);
-		if (offset)
-		{
-			*id_out = id;
-			*addr_out = this->current = offset2host(this->pool, offset);
-			*online = TRUE;
-			return TRUE;
-		}
-		offset = (uintptr_t)this->pool->offline->get(this->pool->offline, id);
-		if (offset)
-		{
-			*id_out = id;
-			*addr_out = this->current = offset2host(this->pool, offset);
-			*online = FALSE;
-			return TRUE;
-		}
-	}
-	return FALSE;
-}
-
-/**
- * Implementation of lease_enumerator_t.destroy
- */
-static void lease_enumerator_destroy(lease_enumerator_t *this)
-{
-	DESTROY_IF(this->current);
-	this->inner->destroy(this->inner);
-	this->mutex->unlock(this->mutex);
-	free(this);
-}
-
-/**
  * Implementation of stroke_attribute_t.create_lease_enumerator
  */
 static enumerator_t* create_lease_enumerator(private_stroke_attribute_t *this,
-											 char *pool)
+											 char *name)
 {
-	lease_enumerator_t *enumerator;
-
+	mem_pool_t *pool;
 	this->mutex->lock(this->mutex);
-	enumerator = malloc_thing(lease_enumerator_t);
-	enumerator->pool = find_pool(this, pool);
-	if (!enumerator->pool)
+	pool = find_pool(this, name);
+	if (!pool)
 	{
 		this->mutex->unlock(this->mutex);
-		free(enumerator);
 		return NULL;
 	}
-	enumerator->public.enumerate = (void*)lease_enumerate;
-	enumerator->public.destroy = (void*)lease_enumerator_destroy;
-	enumerator->inner = enumerator->pool->ids->create_enumerator(enumerator->pool->ids);
-	enumerator->mutex = this->mutex;
-	enumerator->current = NULL;
-	return &enumerator->public;
+	return enumerator_create_cleaner(pool->create_lease_enumerator(pool),
+									 (void*)this->mutex->unlock, this->mutex);
 }
 
 /**
@@ -518,7 +208,7 @@ static enumerator_t* create_lease_enumerator(private_stroke_attribute_t *this,
 static void destroy(private_stroke_attribute_t *this)
 {
 	this->mutex->destroy(this->mutex);
-	this->pools->destroy_function(this->pools, (void*)pool_destroy);
+	this->pools->destroy_offset(this->pools, offsetof(mem_pool_t, destroy));
 	free(this);
 }
 
diff --git a/src/libcharon/plugins/stroke/stroke_attribute.h b/src/libcharon/plugins/stroke/stroke_attribute.h
index cf6c950a6..249a9899b 100644
--- a/src/libcharon/plugins/stroke/stroke_attribute.h
+++ b/src/libcharon/plugins/stroke/stroke_attribute.h
@@ -37,15 +37,14 @@ struct stroke_attribute_t {
 	attribute_provider_t provider;
 
 	/**
-	 * Add a virtual IP address.
+	 * Add a virtual IP address pool.
 	 *
 	 * @param msg		stroke message
-	 * @param end		end of stroke message that contains virtual IP.
 	 */
 	void (*add_pool)(stroke_attribute_t *this, stroke_msg_t *msg);
 
 	/**
-	 * Remove a virtual IP address.
+	 * Remove a virtual IP address pool.
 	 *
 	 * @param msg		stroke message
 	 */
@@ -68,10 +67,11 @@ struct stroke_attribute_t {
 	 * identification_t *id, host_t *address, bool online
 	 *
 	 * @param pool		name of the pool to enumerate
-	 * @return 			enumerator, NULL if pool not found
+	 * @return			enumerator, NULL if pool not found
 	 */
 	enumerator_t* (*create_lease_enumerator)(stroke_attribute_t *this,
 											 char *pool);
+
 	/**
 	 * Destroy a stroke_attribute instance.
 	 */
diff --git a/src/libhydra/Makefile.am b/src/libhydra/Makefile.am
index 94d3968de..c669b4e11 100644
--- a/src/libhydra/Makefile.am
+++ b/src/libhydra/Makefile.am
@@ -4,7 +4,8 @@ libhydra_la_SOURCES = \
 hydra.c hydra.h \
 attributes/attributes.c attributes/attributes.h \
 attributes/attribute_provider.h attributes/attribute_handler.h \
-attributes/attribute_manager.c attributes/attribute_manager.h
+attributes/attribute_manager.c attributes/attribute_manager.h \
+attributes/mem_pool.c attributes/mem_pool.h
 
 libhydra_la_LIBADD =
 
diff --git a/src/libhydra/attributes/mem_pool.c b/src/libhydra/attributes/mem_pool.c
new file mode 100644
index 000000000..bba793f28
--- /dev/null
+++ b/src/libhydra/attributes/mem_pool.c
@@ -0,0 +1,429 @@
+/*
+ * Copyright (C) 2010 Tobias Brunner
+ * Copyright (C) 2008 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.
+ */
+
+#include "mem_pool.h"
+
+#include <debug.h>
+#include <utils/hashtable.h>
+
+#define POOL_LIMIT (sizeof(uintptr_t)*8)
+
+typedef struct private_mem_pool_t private_mem_pool_t;
+
+/**
+ * private data of mem_pool_t
+ */
+struct private_mem_pool_t {
+	/**
+	 * public interface
+	 */
+	mem_pool_t public;
+
+	/**
+	 * name of the pool
+	 */
+	char *name;
+
+	/**
+	 * base address of the pool
+	 */
+	host_t *base;
+
+	/**
+	 * size of the pool
+	 */
+	u_int size;
+
+	/**
+	 * next unused address
+	 */
+	u_int unused;
+
+	/**
+	 * hashtable [identity => offset], for online leases
+	 */
+	hashtable_t *online;
+
+	/**
+	 * hashtable [identity => offset], for offline leases
+	 */
+	hashtable_t *offline;
+
+	/**
+	 * hashtable [identity => identity], handles identity references
+	 */
+	hashtable_t *ids;
+};
+
+/**
+ * hashtable hash function for identities
+ */
+static u_int id_hash(identification_t *id)
+{
+	return chunk_hash(id->get_encoding(id));
+}
+
+/**
+ * hashtable equals function for identities
+ */
+static bool id_equals(identification_t *a, identification_t *b)
+{
+	return a->equals(a, b);
+}
+
+/**
+ * convert a pool offset to an address
+ */
+static host_t* offset2host(private_mem_pool_t *pool, int offset)
+{
+	chunk_t addr;
+	host_t *host;
+	u_int32_t *pos;
+
+	offset--;
+	if (offset > pool->size)
+	{
+		return NULL;
+	}
+
+	addr = chunk_clone(pool->base->get_address(pool->base));
+	if (pool->base->get_family(pool->base) == AF_INET6)
+	{
+		pos = (u_int32_t*)(addr.ptr + 12);
+	}
+	else
+	{
+		pos = (u_int32_t*)addr.ptr;
+	}
+	*pos = htonl(offset + ntohl(*pos));
+	host = host_create_from_chunk(pool->base->get_family(pool->base), addr, 0);
+	free(addr.ptr);
+	return host;
+}
+
+/**
+ * convert a host to a pool offset
+ */
+static int host2offset(private_mem_pool_t *pool, host_t *addr)
+{
+	chunk_t host, base;
+	u_int32_t hosti, basei;
+
+	if (addr->get_family(addr) != pool->base->get_family(pool->base))
+	{
+		return -1;
+	}
+	host = addr->get_address(addr);
+	base = pool->base->get_address(pool->base);
+	if (addr->get_family(addr) == AF_INET6)
+	{
+		/* only look at last /32 block */
+		if (!memeq(host.ptr, base.ptr, 12))
+		{
+			return -1;
+		}
+		host = chunk_skip(host, 12);
+		base = chunk_skip(base, 12);
+	}
+	hosti = ntohl(*(u_int32_t*)(host.ptr));
+	basei = ntohl(*(u_int32_t*)(base.ptr));
+	if (hosti > basei + pool->size)
+	{
+		return -1;
+	}
+	return hosti - basei + 1;
+}
+
+METHOD(mem_pool_t, get_name, const char*,
+	   private_mem_pool_t *this)
+{
+	return this->name;
+}
+
+METHOD(mem_pool_t, get_size, u_int,
+	   private_mem_pool_t *this)
+{
+	return this->size;
+}
+
+METHOD(mem_pool_t, get_online, u_int,
+	   private_mem_pool_t *this)
+{
+	return this->online->get_count(this->online);
+}
+
+METHOD(mem_pool_t, get_offline, u_int,
+	   private_mem_pool_t *this)
+{
+	return this->offline->get_count(this->offline);
+}
+
+METHOD(mem_pool_t, acquire_address, host_t*,
+	   private_mem_pool_t *this, identification_t *id, host_t *requested)
+{
+	uintptr_t offset = 0;
+	enumerator_t *enumerator;
+	identification_t *old_id;
+
+	/* if the pool is empty (e.g. in the %config case) we simply return the
+	 * requested address */
+	if (this->size == 0)
+	{
+		return requested->clone(requested);
+	}
+
+	while (TRUE)
+	{
+		if (!requested->is_anyaddr(requested) &&
+			requested->get_family(requested) !=
+			this->base->get_family(this->base))
+		{
+			DBG1("IP pool address family mismatch");
+			break;
+		}
+
+		/* check for a valid offline lease, refresh */
+		offset = (uintptr_t)this->offline->remove(this->offline, id);
+		if (offset)
+		{
+			id = this->ids->get(this->ids, id);
+			if (id)
+			{
+				DBG1("reassigning offline lease to '%Y'", id);
+				this->online->put(this->online, id, (void*)offset);
+				break;
+			}
+		}
+
+		/* check for a valid online lease, reassign */
+		offset = (uintptr_t)this->online->get(this->online, id);
+		if (offset && offset == host2offset(this, requested))
+		{
+			DBG1("reassigning online lease to '%Y'", id);
+			break;
+		}
+
+		if (this->unused < this->size)
+		{
+			/* assigning offset, starting by 1. Handling 0 in hashtable
+			 * is difficult. */
+			offset = ++this->unused;
+			id = id->clone(id);
+			this->ids->put(this->ids, id, id);
+			this->online->put(this->online, id, (void*)offset);
+			DBG1("assigning new lease to '%Y'", id);
+			break;
+		}
+
+		/* no more addresses, replace the first found offline lease */
+		enumerator = this->offline->create_enumerator(this->offline);
+		if (enumerator->enumerate(enumerator, &old_id, &offset))
+		{
+			offset = (uintptr_t)this->offline->remove(this->offline, old_id);
+			if (offset)
+			{
+				/* destroy reference to old ID */
+				old_id = this->ids->remove(this->ids, old_id);
+				DBG1("reassigning existing offline lease by '%Y' to '%Y'",
+					 old_id, id);
+				if (old_id)
+				{
+					old_id->destroy(old_id);
+				}
+				id = id->clone(id);
+				this->ids->put(this->ids, id, id);
+				this->online->put(this->online, id, (void*)offset);
+				enumerator->destroy(enumerator);
+				break;
+			}
+		}
+		enumerator->destroy(enumerator);
+
+		DBG1("pool '%s' is full, unable to assign address", this->name);
+		break;
+	}
+
+	if (offset)
+	{
+		return offset2host(this, offset);
+	}
+	return NULL;
+}
+
+METHOD(mem_pool_t, release_address, bool,
+	   private_mem_pool_t *this, host_t *address, identification_t *id)
+{
+	uintptr_t offset;
+	if (this->size != 0)
+	{
+		offset = (uintptr_t)this->online->remove(this->online, id);
+		if (offset)
+		{
+			id = this->ids->get(this->ids, id);
+			if (id)
+			{
+				DBG1("lease %H by '%Y' went offline", address, id);
+				this->offline->put(this->offline, id, (void*)offset);
+				return TRUE;
+			}
+		}
+	}
+	return FALSE;
+}
+
+/**
+ * lease enumerator
+ */
+typedef struct {
+	/** implemented enumerator interface */
+	enumerator_t public;
+	/** inner hash-table enumerator */
+	enumerator_t *inner;
+	/** enumerated pool */
+	private_mem_pool_t *pool;
+	/** currently enumerated lease address */
+	host_t *current;
+} lease_enumerator_t;
+
+METHOD(enumerator_t, lease_enumerate, bool,
+	   lease_enumerator_t *this, identification_t **id_out, host_t **addr_out,
+	   bool *online)
+{
+	identification_t *id;
+	uintptr_t offset;
+
+	DESTROY_IF(this->current);
+	this->current = NULL;
+
+	if (this->inner->enumerate(this->inner, &id, NULL))
+	{
+		offset = (uintptr_t)this->pool->online->get(this->pool->online, id);
+		if (offset)
+		{
+			*id_out = id;
+			*addr_out = this->current = offset2host(this->pool, offset);
+			*online = TRUE;
+			return TRUE;
+		}
+		offset = (uintptr_t)this->pool->offline->get(this->pool->offline, id);
+		if (offset)
+		{
+			*id_out = id;
+			*addr_out = this->current = offset2host(this->pool, offset);
+			*online = FALSE;
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+METHOD(enumerator_t, lease_enumerator_destroy, void,
+	   lease_enumerator_t *this)
+{
+	DESTROY_IF(this->current);
+	this->inner->destroy(this->inner);
+	free(this);
+}
+
+METHOD(mem_pool_t, create_lease_enumerator, enumerator_t*,
+	   private_mem_pool_t *this)
+{
+	lease_enumerator_t *enumerator;
+
+	INIT(enumerator,
+		.public = {
+			.enumerate = (void*)_lease_enumerate,
+			.destroy = (void*)_lease_enumerator_destroy,
+		},
+		.pool = this,
+		.inner = this->ids->create_enumerator(this->ids),
+	);
+
+	return &enumerator->public;
+}
+
+METHOD(mem_pool_t, destroy, void,
+	   private_mem_pool_t *this)
+{
+	enumerator_t *enumerator;
+	identification_t *id;
+
+	enumerator = this->ids->create_enumerator(this->ids);
+	while (enumerator->enumerate(enumerator, &id, NULL))
+	{
+		id->destroy(id);
+	}
+	enumerator->destroy(enumerator);
+
+	this->ids->destroy(this->ids);
+	this->online->destroy(this->online);
+	this->offline->destroy(this->offline);
+	DESTROY_IF(this->base);
+	free(this->name);
+	free(this);
+}
+
+/**
+ * Described in header
+ */
+mem_pool_t *mem_pool_create(char *name, host_t *base, int bits)
+{
+	private_mem_pool_t *this;
+
+	INIT(this,
+		.public = {
+			.get_name = _get_name,
+			.get_size = _get_size,
+			.get_online = _get_online,
+			.get_offline = _get_offline,
+			.acquire_address = _acquire_address,
+			.release_address = _release_address,
+			.create_lease_enumerator = _create_lease_enumerator,
+			.destroy = _destroy,
+		},
+		.name = strdup(name),
+		.online = hashtable_create((hashtable_hash_t)id_hash,
+								   (hashtable_equals_t)id_equals, 16),
+		.offline = hashtable_create((hashtable_hash_t)id_hash,
+									(hashtable_equals_t)id_equals, 16),
+		.ids = hashtable_create((hashtable_hash_t)id_hash,
+								(hashtable_equals_t)id_equals, 16),
+	);
+
+	if (base)
+	{
+		int addr_bits = base->get_family(base) == AF_INET ? 32 : 128;
+		/* net bits -> host bits */
+		bits = addr_bits - bits;
+		if (bits > POOL_LIMIT)
+		{
+			bits = POOL_LIMIT;
+			DBG1("virtual IP pool too large, limiting to %H/%d",
+				 base, addr_bits - bits);
+		}
+		this->size = 1 << (bits);
+
+		if (this->size > 2)
+		{	/* do not use first and last addresses of a block */
+			this->unused++;
+			this->size--;
+		}
+		this->base = base->clone(base);
+	}
+
+	return &this->public;
+}
+
diff --git a/src/libhydra/attributes/mem_pool.h b/src/libhydra/attributes/mem_pool.h
new file mode 100644
index 000000000..6685fd61a
--- /dev/null
+++ b/src/libhydra/attributes/mem_pool.h
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2010 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 mem_pool mem_pool
+ * @{ @ingroup attributes
+ */
+
+#ifndef MEM_POOL_H
+#define MEM_POOL_H
+
+typedef struct mem_pool_t mem_pool_t;
+
+#include <utils/host.h>
+#include <utils/identification.h>
+
+/**
+ * An in-memory IP address pool.
+ *
+ * @note the implementation is not thread-safe.
+ */
+struct mem_pool_t {
+
+	/**
+	 * Get the name of this pool.
+	 *
+	 * @return			the name of this pool
+	 */
+	const char* (*get_name)(mem_pool_t *this);
+
+	/**
+	 * Get the size (i.e. number of addresses) of this pool.
+	 *
+	 * @return			the size of this pool
+	 */
+	u_int (*get_size)(mem_pool_t *this);
+
+	/**
+	 * Get the number of online leases.
+	 *
+	 * @return			the number of offline leases
+	 */
+	u_int (*get_online)(mem_pool_t *this);
+
+	/**
+	 * Get the number of offline leases.
+	 *
+	 * @return			the number of online leases
+	 */
+	u_int (*get_offline)(mem_pool_t *this);
+
+	/**
+	 * Acquire an address for the given id from this pool.
+	 *
+	 * @param id		the id to acquire an address for
+	 * @param requested	acquire this address, if possible
+	 * @return			the acquired address
+	 */
+	host_t* (*acquire_address)(mem_pool_t *this, identification_t *id,
+							   host_t *requested);
+
+	/**
+	 * Release a previously acquired address.
+	 *
+	 * @param address	the address to release
+	 * @param id		the id the address was assigned to
+	 * @return			TRUE, if the lease was found
+	 */
+	bool (*release_address)(mem_pool_t *this, host_t *address,
+							identification_t *id);
+
+	/**
+	 * Create an enumerator over the leases of this pool.
+	 *
+	 * Enumerator enumerates over
+	 * identification_t *id, host_t *address, bool online
+	 *
+	 * @return			enumerator
+	 */
+	enumerator_t* (*create_lease_enumerator)(mem_pool_t *this);
+
+	/**
+	 * Destroy a mem_pool_t instance.
+	 */
+	void (*destroy)(mem_pool_t *this);
+};
+
+/**
+ * Create an in-memory IP address pool.
+ *
+ * An empty pool just returns the requested address.
+ *
+ * @param name		name of this pool
+ * @param base		base address of this pool, NULL to create an empty pool
+ * @param bits		net mask
+ */
+mem_pool_t *mem_pool_create(char *name, host_t *base, int bits);
+
+#endif /** MEM_POOL_H_ @} */
+