Imported Upstream version 5.5.0

15 files changed, 471 insertions, 235 deletions

diff --git a/src/libcharon/sa/ikev2/tasks/child_create.c b/src/libcharon/sa/ikev2/tasks/child_create.c
index 3d4ded944..64a82850b 100644
--- a/src/libcharon/sa/ikev2/tasks/child_create.c
+++ b/src/libcharon/sa/ikev2/tasks/child_create.c
@@ -1,8 +1,8 @@
 /*
- * Copyright (C) 2008 Tobias Brunner
+ * Copyright (C) 2008-2016 Tobias Brunner
  * Copyright (C) 2005-2008 Martin Willi
  * Copyright (C) 2005 Jan Hutter
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -29,7 +29,7 @@
 #include <encoding/payloads/delete_payload.h>
 #include <processing/jobs/delete_ike_sa_job.h>
 #include <processing/jobs/inactivity_job.h>
-
+#include <processing/jobs/initiate_tasks_job.h>
 
 typedef struct private_child_create_t private_child_create_t;
 
@@ -151,27 +151,27 @@ struct private_child_create_t {
 	/**
 	 * Own allocated SPI
 	 */
-	u_int32_t my_spi;
+	uint32_t my_spi;
 
 	/**
 	 * SPI received in proposal
 	 */
-	u_int32_t other_spi;
+	uint32_t other_spi;
 
 	/**
 	 * Own allocated Compression Parameter Index (CPI)
 	 */
-	u_int16_t my_cpi;
+	uint16_t my_cpi;
 
 	/**
 	 * Other Compression Parameter Index (CPI), received via IPCOMP_SUPPORTED
 	 */
-	u_int16_t other_cpi;
+	uint16_t other_cpi;
 
 	/**
 	 * reqid to use if we are rekeying
 	 */
-	u_int32_t reqid;
+	uint32_t reqid;
 
 	/**
 	 * Explicit inbound mark value
@@ -205,6 +205,25 @@ struct private_child_create_t {
 };
 
 /**
+ * Schedule a retry if creating the CHILD_SA temporary failed
+ */
+static void schedule_delayed_retry(private_child_create_t *this)
+{
+	child_create_t *task;
+	uint32_t retry;
+
+	retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
+
+	task = child_create_create(this->ike_sa,
+							   this->config->get_ref(this->config), FALSE,
+							   this->packet_tsi, this->packet_tsr);
+	task->use_reqid(task, this->reqid);
+	DBG1(DBG_IKE, "creating CHILD_SA failed, trying again in %d seconds",
+		 retry);
+	this->ike_sa->queue_task_delayed(this->ike_sa, (task_t*)task, retry);
+}
+
+/**
  * get the nonce from a message
  */
 static status_t get_nonce(message_t *message, chunk_t *nonce)
@@ -306,7 +325,7 @@ static bool allocate_spi(private_child_create_t *this)
  */
 static void schedule_inactivity_timeout(private_child_create_t *this)
 {
-	u_int32_t timeout, id;
+	uint32_t timeout, id;
 	bool close_ike;
 
 	timeout = this->config->get_inactivity(this->config);
@@ -386,7 +405,7 @@ static linked_list_t* get_transport_nat_ts(private_child_create_t *this,
 	linked_list_t *out;
 	traffic_selector_t *ts;
 	host_t *ike, *first = NULL;
-	u_int8_t mask;
+	uint8_t mask;
 
 	if (local)
 	{
@@ -464,7 +483,7 @@ static status_t select_and_install(private_child_create_t *this,
 	chunk_t integ_i = chunk_empty, integ_r = chunk_empty;
 	linked_list_t *my_ts, *other_ts;
 	host_t *me, *other;
-	bool private;
+	bool private, prefer_configured;
 
 	if (this->proposals == NULL)
 	{
@@ -481,8 +500,10 @@ static status_t select_and_install(private_child_create_t *this,
 	other = this->ike_sa->get_other_host(this->ike_sa);
 
 	private = this->ike_sa->supports_extension(this->ike_sa, EXT_STRONGSWAN);
+	prefer_configured = lib->settings->get_bool(lib->settings,
+							"%s.prefer_configured_proposals", TRUE, lib->ns);
 	this->proposal = this->config->select_proposal(this->config,
-											this->proposals, no_dh, private);
+							this->proposals, no_dh, private, prefer_configured);
 	if (this->proposal == NULL)
 	{
 		DBG1(DBG_IKE, "no acceptable proposal found");
@@ -501,7 +522,7 @@ static status_t select_and_install(private_child_create_t *this,
 
 	if (!this->proposal->has_dh_group(this->proposal, this->dh_group))
 	{
-		u_int16_t group;
+		uint16_t group;
 
 		if (this->proposal->get_algorithm(this->proposal, DIFFIE_HELLMAN_GROUP,
 										  &group, NULL))
@@ -798,7 +819,7 @@ static bool build_payloads(private_child_create_t *this, message_t *message)
  * Adds an IPCOMP_SUPPORTED notify to the message, allocating a CPI
  */
 static void add_ipcomp_notify(private_child_create_t *this,
-								  message_t *message, u_int8_t ipcomp)
+								  message_t *message, uint8_t ipcomp)
 {
 	this->my_cpi = this->child_sa->alloc_cpi(this->child_sa);
 	if (this->my_cpi)
@@ -838,11 +859,11 @@ static void handle_notify(private_child_create_t *this, notify_payload_t *notify
 		case IPCOMP_SUPPORTED:
 		{
 			ipcomp_transform_t ipcomp;
-			u_int16_t cpi;
+			uint16_t cpi;
 			chunk_t data;
 
 			data = notify->get_notification_data(notify);
-			cpi = *(u_int16_t*)data.ptr;
+			cpi = *(uint16_t*)data.ptr;
 			ipcomp = (ipcomp_transform_t)(*(data.ptr + 2));
 			switch (ipcomp)
 			{
@@ -1232,13 +1253,13 @@ METHOD(task_t, build_r, status_t,
 	if (this->ike_sa->get_state(this->ike_sa) == IKE_REKEYING)
 	{
 		DBG1(DBG_IKE, "unable to create CHILD_SA while rekeying IKE_SA");
-		message->add_notify(message, TRUE, NO_ADDITIONAL_SAS, chunk_empty);
+		message->add_notify(message, TRUE, TEMPORARY_FAILURE, chunk_empty);
 		return SUCCESS;
 	}
 	if (this->ike_sa->get_state(this->ike_sa) == IKE_DELETING)
 	{
 		DBG1(DBG_IKE, "unable to create CHILD_SA while deleting IKE_SA");
-		message->add_notify(message, TRUE, NO_ADDITIONAL_SAS, chunk_empty);
+		message->add_notify(message, TRUE, TEMPORARY_FAILURE, chunk_empty);
 		return SUCCESS;
 	}
 
@@ -1310,7 +1331,7 @@ METHOD(task_t, build_r, status_t,
 			return SUCCESS;
 		case INVALID_ARG:
 		{
-			u_int16_t group = htons(this->dh_group);
+			uint16_t group = htons(this->dh_group);
 			message->add_notify(message, FALSE, INVALID_KE_PAYLOAD,
 								chunk_from_thing(group));
 			handle_child_sa_failure(this, message);
@@ -1441,10 +1462,21 @@ METHOD(task_t, process_i, status_t,
 					/* an error in CHILD_SA creation is not critical */
 					return SUCCESS;
 				}
+				case TEMPORARY_FAILURE:
+				{
+					DBG1(DBG_IKE, "received %N notify, will retry later",
+						 notify_type_names, type);
+					enumerator->destroy(enumerator);
+					if (!this->rekey)
+					{	/* the rekey task will retry itself if necessary */
+						schedule_delayed_retry(this);
+					}
+					return SUCCESS;
+				}
 				case INVALID_KE_PAYLOAD:
 				{
 					chunk_t data;
-					u_int16_t group = MODP_NONE;
+					uint16_t group = MODP_NONE;
 
 					data = notify->get_notification_data(notify);
 					if (data.len == sizeof(group))
@@ -1529,7 +1561,7 @@ METHOD(task_t, process_i, status_t,
 }
 
 METHOD(child_create_t, use_reqid, void,
-	private_child_create_t *this, u_int32_t reqid)
+	private_child_create_t *this, uint32_t reqid)
 {
 	this->reqid = reqid;
 }
diff --git a/src/libcharon/sa/ikev2/tasks/child_create.h b/src/libcharon/sa/ikev2/tasks/child_create.h
index 46d9403ee..f48d7b0a9 100644
--- a/src/libcharon/sa/ikev2/tasks/child_create.h
+++ b/src/libcharon/sa/ikev2/tasks/child_create.h
@@ -49,7 +49,7 @@ struct child_create_t {
 	 *
 	 * @param reqid		reqid to use
 	 */
-	void (*use_reqid) (child_create_t *this, u_int32_t reqid);
+	void (*use_reqid) (child_create_t *this, uint32_t reqid);
 
 	/**
 	 * Use specific mark values to override configuration.
diff --git a/src/libcharon/sa/ikev2/tasks/child_delete.c b/src/libcharon/sa/ikev2/tasks/child_delete.c
index 877ae0531..6fa8836ac 100644
--- a/src/libcharon/sa/ikev2/tasks/child_delete.c
+++ b/src/libcharon/sa/ikev2/tasks/child_delete.c
@@ -1,6 +1,7 @@
 /*
+ * Copyright (C) 2009-2016 Tobias Brunner
  * Copyright (C) 2006-2007 Martin Willi
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -18,7 +19,7 @@
 #include <daemon.h>
 #include <encoding/payloads/delete_payload.h>
 #include <sa/ikev2/tasks/child_create.h>
-
+#include <sa/ikev2/tasks/child_rekey.h>
 
 typedef struct private_child_delete_t private_child_delete_t;
 
@@ -50,7 +51,7 @@ struct private_child_delete_t {
 	/**
 	 * Inbound SPI of CHILD_SA to delete
 	 */
-	u_int32_t spi;
+	uint32_t spi;
 
 	/**
 	 * whether to enforce delete action policy
@@ -86,7 +87,7 @@ static void build_payloads(private_child_delete_t *this, message_t *message)
 	while (enumerator->enumerate(enumerator, (void**)&child_sa))
 	{
 		protocol_id_t protocol = child_sa->get_protocol(child_sa);
-		u_int32_t spi = child_sa->get_spi(child_sa, TRUE);
+		uint32_t spi = child_sa->get_spi(child_sa, TRUE);
 
 		switch (protocol)
 		{
@@ -119,6 +120,33 @@ static void build_payloads(private_child_delete_t *this, message_t *message)
 }
 
 /**
+ * Check if the given CHILD_SA is the redundant SA created in a rekey collision.
+ */
+static bool is_redundant(private_child_delete_t *this, child_sa_t *child)
+{
+	enumerator_t *tasks;
+	task_t *task;
+
+	tasks = this->ike_sa->create_task_enumerator(this->ike_sa,
+												 TASK_QUEUE_ACTIVE);
+	while (tasks->enumerate(tasks, &task))
+	{
+		if (task->get_type(task) == TASK_CHILD_REKEY)
+		{
+			child_rekey_t *rekey = (child_rekey_t*)task;
+
+			if (rekey->is_redundant(rekey, child))
+			{
+				tasks->destroy(tasks);
+				return TRUE;
+			}
+		}
+	}
+	tasks->destroy(tasks);
+	return FALSE;
+}
+
+/**
  * read in payloads and find the children to delete
  */
 static void process_payloads(private_child_delete_t *this, message_t *message)
@@ -126,7 +154,7 @@ static void process_payloads(private_child_delete_t *this, message_t *message)
 	enumerator_t *payloads, *spis;
 	payload_t *payload;
 	delete_payload_t *delete_payload;
-	u_int32_t spi;
+	uint32_t spi;
 	protocol_id_t protocol;
 	child_sa_t *child_sa;
 
@@ -157,24 +185,31 @@ static void process_payloads(private_child_delete_t *this, message_t *message)
 
 				switch (child_sa->get_state(child_sa))
 				{
-					case CHILD_REKEYING:
+					case CHILD_REKEYED:
 						this->rekeyed = TRUE;
-						/* we reply as usual, rekeying will fail */
 						break;
 					case CHILD_DELETING:
 						/* we don't send back a delete if we initiated ourself */
 						if (!this->initiator)
 						{
-							this->ike_sa->destroy_child_sa(this->ike_sa,
-														   protocol, spi);
 							continue;
 						}
 						/* fall through */
+					case CHILD_REKEYING:
+						/* we reply as usual, rekeying will fail */
 					case CHILD_INSTALLED:
 						if (!this->initiator)
-						{	/* reestablish installed children if required */
-							this->check_delete_action = TRUE;
+						{
+							if (is_redundant(this, child_sa))
+							{
+								this->rekeyed = TRUE;
+							}
+							else
+							{
+								this->check_delete_action = TRUE;
+							}
 						}
+						break;
 					default:
 						break;
 				}
@@ -199,14 +234,14 @@ static status_t destroy_and_reestablish(private_child_delete_t *this)
 	child_sa_t *child_sa;
 	child_cfg_t *child_cfg;
 	protocol_id_t protocol;
-	u_int32_t spi, reqid;
+	uint32_t spi, reqid;
 	action_t action;
 	status_t status = SUCCESS;
 
 	enumerator = this->child_sas->create_enumerator(this->child_sas);
 	while (enumerator->enumerate(enumerator, (void**)&child_sa))
 	{
-		/* signal child down event if we are not rekeying */
+		/* signal child down event if we weren't rekeying */
 		if (!this->rekeyed)
 		{
 			charon->bus->child_updown(charon->bus, child_sa, FALSE);
@@ -254,7 +289,7 @@ static void log_children(private_child_delete_t *this)
 	linked_list_t *my_ts, *other_ts;
 	enumerator_t *enumerator;
 	child_sa_t *child_sa;
-	u_int64_t bytes_in, bytes_out;
+	uint64_t bytes_in, bytes_out;
 
 	enumerator = this->child_sas->create_enumerator(this->child_sas);
 	while (enumerator->enumerate(enumerator, (void**)&child_sa))
@@ -308,7 +343,7 @@ METHOD(task_t, build_i, status_t,
 		this->spi = child_sa->get_spi(child_sa, TRUE);
 	}
 	this->child_sas->insert_last(this->child_sas, child_sa);
-	if (child_sa->get_state(child_sa) == CHILD_REKEYING)
+	if (child_sa->get_state(child_sa) == CHILD_REKEYED)
 	{
 		this->rekeyed = TRUE;
 	}
@@ -347,11 +382,7 @@ METHOD(task_t, process_r, status_t,
 METHOD(task_t, build_r, status_t,
 	private_child_delete_t *this, message_t *message)
 {
-	/* if we are rekeying, we send an empty informational */
-	if (this->ike_sa->get_state(this->ike_sa) != IKE_REKEYING)
-	{
-		build_payloads(this, message);
-	}
+	build_payloads(this, message);
 	DBG1(DBG_IKE, "CHILD_SA closed");
 	return destroy_and_reestablish(this);
 }
@@ -391,7 +422,7 @@ METHOD(task_t, destroy, void,
  * Described in header.
  */
 child_delete_t *child_delete_create(ike_sa_t *ike_sa, protocol_id_t protocol,
-									u_int32_t spi, bool expired)
+									uint32_t spi, bool expired)
 {
 	private_child_delete_t *this;
 
diff --git a/src/libcharon/sa/ikev2/tasks/child_delete.h b/src/libcharon/sa/ikev2/tasks/child_delete.h
index 1ada0699e..1e9b2d2f7 100644
--- a/src/libcharon/sa/ikev2/tasks/child_delete.h
+++ b/src/libcharon/sa/ikev2/tasks/child_delete.h
@@ -56,6 +56,6 @@ struct child_delete_t {
  * @return				child_delete task to handle by the task_manager
  */
 child_delete_t *child_delete_create(ike_sa_t *ike_sa, protocol_id_t protocol,
-									u_int32_t spi, bool expired);
+									uint32_t spi, bool expired);
 
 #endif /** CHILD_DELETE_H_ @}*/
diff --git a/src/libcharon/sa/ikev2/tasks/child_rekey.c b/src/libcharon/sa/ikev2/tasks/child_rekey.c
index 6f0c2b2c7..c04ec141f 100644
--- a/src/libcharon/sa/ikev2/tasks/child_rekey.c
+++ b/src/libcharon/sa/ikev2/tasks/child_rekey.c
@@ -1,7 +1,8 @@
 /*
+ * Copyright (C) 2009-2016 Tobias Brunner
  * Copyright (C) 2005-2007 Martin Willi
  * Copyright (C) 2005 Jan Hutter
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -54,7 +55,7 @@ struct private_child_rekey_t {
 	/**
 	 * Inbound SPI of CHILD_SA to rekey
 	 */
-	u_int32_t spi;
+	uint32_t spi;
 
 	/**
 	 * the CHILD_CREATE task which is reused to simplify rekeying
@@ -91,7 +92,7 @@ struct private_child_rekey_t {
  */
 static void schedule_delayed_rekey(private_child_rekey_t *this)
 {
-	u_int32_t retry;
+	uint32_t retry;
 	job_t *job;
 
 	retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
@@ -130,7 +131,7 @@ static void find_child(private_child_rekey_t *this, message_t *message)
 {
 	notify_payload_t *notify;
 	protocol_id_t protocol;
-	u_int32_t spi;
+	uint32_t spi;
 
 	notify = message->get_notify(message, REKEY_SA);
 	if (notify)
@@ -150,7 +151,7 @@ METHOD(task_t, build_i, status_t,
 	private_child_rekey_t *this, message_t *message)
 {
 	notify_payload_t *notify;
-	u_int32_t reqid;
+	uint32_t reqid;
 	child_cfg_t *config;
 
 	this->child_sa = this->ike_sa->get_child_sa(this->ike_sa, this->protocol,
@@ -159,14 +160,21 @@ METHOD(task_t, build_i, status_t,
 	{	/* check if it is an outbound CHILD_SA */
 		this->child_sa = this->ike_sa->get_child_sa(this->ike_sa, this->protocol,
 													this->spi, FALSE);
-		if (!this->child_sa)
-		{	/* CHILD_SA is gone, unable to rekey. As an empty CREATE_CHILD_SA
-			 * exchange is invalid, we fall back to an INFORMATIONAL exchange.*/
-			message->set_exchange_type(message, INFORMATIONAL);
-			return SUCCESS;
+		if (this->child_sa)
+		{
+			/* we work only with the inbound SPI */
+			this->spi = this->child_sa->get_spi(this->child_sa, TRUE);
 		}
-		/* we work only with the inbound SPI */
-		this->spi = this->child_sa->get_spi(this->child_sa, TRUE);
+	}
+	if (!this->child_sa ||
+		(!this->child_create &&
+		  this->child_sa->get_state(this->child_sa) != CHILD_INSTALLED) ||
+		(this->child_create &&
+		 this->child_sa->get_state(this->child_sa) != CHILD_REKEYING))
+	{
+		/* CHILD_SA is gone or in the wrong state, unable to rekey */
+		message->set_exchange_type(message, EXCHANGE_TYPE_UNDEFINED);
+		return SUCCESS;
 	}
 	config = this->child_sa->get_config(this->child_sa);
 
@@ -217,13 +225,19 @@ METHOD(task_t, build_r, status_t,
 	private_child_rekey_t *this, message_t *message)
 {
 	child_cfg_t *config;
-	u_int32_t reqid;
+	uint32_t reqid;
+	child_sa_state_t state;
 
-	if (this->child_sa == NULL ||
-		this->child_sa->get_state(this->child_sa) == CHILD_DELETING)
+	if (!this->child_sa)
 	{
 		DBG1(DBG_IKE, "unable to rekey, CHILD_SA not found");
-		message->add_notify(message, TRUE, NO_PROPOSAL_CHOSEN, chunk_empty);
+		message->add_notify(message, TRUE, CHILD_SA_NOT_FOUND, chunk_empty);
+		return SUCCESS;
+	}
+	if (this->child_sa->get_state(this->child_sa) == CHILD_DELETING)
+	{
+		DBG1(DBG_IKE, "unable to rekey, we are deleting the CHILD_SA");
+		message->add_notify(message, TRUE, TEMPORARY_FAILURE, chunk_empty);
 		return SUCCESS;
 	}
 
@@ -237,14 +251,16 @@ METHOD(task_t, build_r, status_t,
 	this->child_create->set_config(this->child_create, config->get_ref(config));
 	this->child_create->task.build(&this->child_create->task, message);
 
+	state = this->child_sa->get_state(this->child_sa);
+	this->child_sa->set_state(this->child_sa, CHILD_REKEYING);
+
 	if (message->get_payload(message, PLV2_SECURITY_ASSOCIATION) == NULL)
-	{
-		/* rekeying failed, reuse old child */
-		this->child_sa->set_state(this->child_sa, CHILD_INSTALLED);
+	{	/* rekeying failed, reuse old child */
+		this->child_sa->set_state(this->child_sa, state);
 		return SUCCESS;
 	}
 
-	this->child_sa->set_state(this->child_sa, CHILD_REKEYING);
+	this->child_sa->set_state(this->child_sa, CHILD_REKEYED);
 
 	/* invoke rekey hook */
 	charon->bus->child_rekey(charon->bus, this->child_sa,
@@ -284,9 +300,9 @@ static child_sa_t *handle_collision(private_child_rekey_t *this)
 				if (child_sa)
 				{
 					child_sa->set_close_action(child_sa, ACTION_NONE);
-					if (child_sa->get_state(child_sa) != CHILD_REKEYING)
+					if (child_sa->get_state(child_sa) != CHILD_REKEYED)
 					{
-						child_sa->set_state(child_sa, CHILD_REKEYING);
+						child_sa->set_state(child_sa, CHILD_REKEYED);
 					}
 				}
 			}
@@ -324,7 +340,7 @@ METHOD(task_t, process_i, status_t,
 	private_child_rekey_t *this, message_t *message)
 {
 	protocol_id_t protocol;
-	u_int32_t spi;
+	uint32_t spi;
 	child_sa_t *to_delete;
 
 	if (message->get_notify(message, NO_ADDITIONAL_SAS))
@@ -337,6 +353,34 @@ METHOD(task_t, process_i, status_t,
 							this->ike_sa->get_id(this->ike_sa), TRUE));
 		return SUCCESS;
 	}
+	if (message->get_notify(message, CHILD_SA_NOT_FOUND))
+	{
+		child_cfg_t *child_cfg;
+		uint32_t reqid;
+
+		if (this->collision &&
+			this->collision->get_type(this->collision) == TASK_CHILD_DELETE)
+		{	/* ignore this error if we already deleted the CHILD_SA on the
+			 * peer's behalf (could happen if the other peer does not detect
+			 * the collision and did not respond with TEMPORARY_FAILURE) */
+			return SUCCESS;
+		}
+		DBG1(DBG_IKE, "peer didn't find the CHILD_SA we tried to rekey");
+		/* FIXME: according to RFC 7296 we should only create a new CHILD_SA if
+		 * it does not exist yet, we currently have no good way of checking for
+		 * that (we could go by name, but that might be tricky e.g. due to
+		 * narrowing) */
+		spi = this->child_sa->get_spi(this->child_sa, TRUE);
+		reqid = this->child_sa->get_reqid(this->child_sa);
+		protocol = this->child_sa->get_protocol(this->child_sa);
+		child_cfg = this->child_sa->get_config(this->child_sa);
+		child_cfg->get_ref(child_cfg);
+		charon->bus->child_updown(charon->bus, this->child_sa, FALSE);
+		this->ike_sa->destroy_child_sa(this->ike_sa, protocol, spi);
+		return this->ike_sa->initiate(this->ike_sa,
+									  child_cfg->get_ref(child_cfg), reqid,
+									  NULL, NULL);
+	}
 
 	if (this->child_create->task.process(&this->child_create->task,
 										 message) == NEED_MORE)
@@ -346,10 +390,10 @@ METHOD(task_t, process_i, status_t,
 	}
 	if (message->get_payload(message, PLV2_SECURITY_ASSOCIATION) == NULL)
 	{
-		/* establishing new child failed, reuse old. but not when we
-		 * received a delete in the meantime */
-		if (!(this->collision &&
-			  this->collision->get_type(this->collision) == TASK_CHILD_DELETE))
+		/* establishing new child failed, reuse old and try again. but not when
+		 * we received a delete in the meantime */
+		if (!this->collision ||
+			 this->collision->get_type(this->collision) != TASK_CHILD_DELETE)
 		{
 			schedule_delayed_rekey(this);
 		}
@@ -377,9 +421,9 @@ METHOD(task_t, process_i, status_t,
 		return SUCCESS;
 	}
 	/* disable updown event for redundant CHILD_SA */
-	if (to_delete->get_state(to_delete) != CHILD_REKEYING)
+	if (to_delete->get_state(to_delete) != CHILD_REKEYED)
 	{
-		to_delete->set_state(to_delete, CHILD_REKEYING);
+		to_delete->set_state(to_delete, CHILD_REKEYED);
 	}
 	spi = to_delete->get_spi(to_delete, TRUE);
 	protocol = to_delete->get_protocol(to_delete);
@@ -398,6 +442,18 @@ METHOD(task_t, get_type, task_type_t,
 	return TASK_CHILD_REKEY;
 }
 
+METHOD(child_rekey_t, is_redundant, bool,
+	private_child_rekey_t *this, child_sa_t *child)
+{
+	if (this->collision &&
+		this->collision->get_type(this->collision) == TASK_CHILD_REKEY)
+	{
+		private_child_rekey_t *rekey = (private_child_rekey_t*)this->collision;
+		return child == rekey->child_create->get_child(rekey->child_create);
+	}
+	return FALSE;
+}
+
 METHOD(child_rekey_t, collide, void,
 	private_child_rekey_t *this, task_t *other)
 {
@@ -406,9 +462,18 @@ METHOD(child_rekey_t, collide, void,
 	if (other->get_type(other) == TASK_CHILD_REKEY)
 	{
 		private_child_rekey_t *rekey = (private_child_rekey_t*)other;
+		child_sa_t *other_child;
+
 		if (rekey->child_sa != this->child_sa)
+		{	/* not the same child => no collision */
+			other->destroy(other);
+			return;
+		}
+		/* ignore passive tasks that did not successfully create a CHILD_SA */
+		other_child = rekey->child_create->get_child(rekey->child_create);
+		if (!other_child ||
+			 other_child->get_state(other_child) != CHILD_INSTALLED)
 		{
-			/* not the same child => no collision */
 			other->destroy(other);
 			return;
 		}
@@ -416,19 +481,11 @@ METHOD(child_rekey_t, collide, void,
 	else if (other->get_type(other) == TASK_CHILD_DELETE)
 	{
 		child_delete_t *del = (child_delete_t*)other;
-		if (this->collision &&
-			this->collision->get_type(this->collision) == TASK_CHILD_REKEY)
+		if (is_redundant(this, del->get_child(del)))
 		{
-			private_child_rekey_t *rekey;
-
-			rekey = (private_child_rekey_t*)this->collision;
-			if (del->get_child(del) == rekey->child_create->get_child(rekey->child_create))
-			{
-				/* peer deletes redundant child created in collision */
-				this->other_child_destroyed = TRUE;
-				other->destroy(other);
-				return;
-			}
+			this->other_child_destroyed = TRUE;
+			other->destroy(other);
+			return;
 		}
 		if (del->get_child(del) != this->child_sa)
 		{
@@ -439,7 +496,7 @@ METHOD(child_rekey_t, collide, void,
 	}
 	else
 	{
-		/* any other task is not critical for collisisions, ignore */
+		/* any other task is not critical for collisions, ignore */
 		other->destroy(other);
 		return;
 	}
@@ -485,7 +542,7 @@ METHOD(task_t, destroy, void,
  * Described in header.
  */
 child_rekey_t *child_rekey_create(ike_sa_t *ike_sa, protocol_id_t protocol,
-								  u_int32_t spi)
+								  uint32_t spi)
 {
 	private_child_rekey_t *this;
 
@@ -496,6 +553,7 @@ child_rekey_t *child_rekey_create(ike_sa_t *ike_sa, protocol_id_t protocol,
 				.migrate = _migrate,
 				.destroy = _destroy,
 			},
+			.is_redundant = _is_redundant,
 			.collide = _collide,
 		},
 		.ike_sa = ike_sa,
diff --git a/src/libcharon/sa/ikev2/tasks/child_rekey.h b/src/libcharon/sa/ikev2/tasks/child_rekey.h
index 23384653d..0ad1a062d 100644
--- a/src/libcharon/sa/ikev2/tasks/child_rekey.h
+++ b/src/libcharon/sa/ikev2/tasks/child_rekey.h
@@ -1,6 +1,7 @@
 /*
+ * Copyright (C) 2016 Tobias Brunner
  * Copyright (C) 2007 Martin Willi
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -39,13 +40,25 @@ struct child_rekey_t {
 	task_t task;
 
 	/**
-	 * Register a rekeying task which collides with this one
+	 * Check if the given SA is the redundant CHILD_SA created during a rekey
+	 * collision.
+	 *
+	 * This is called if the other peer deletes the redundant SA before we were
+	 * able to handle the CREATE_CHILD_SA response.
+	 *
+	 * @param child		CHILD_SA to check
+	 * @return			TRUE if the SA is the redundant CHILD_SA
+	 */
+	bool (*is_redundant)(child_rekey_t *this, child_sa_t *child);
+
+	/**
+	 * Register a rekeying/delete task which collides with this one
 	 *
 	 * If two peers initiate rekeying at the same time, the collision must
 	 * be handled gracefully. The task manager is aware of what exchanges
-	 * are going on and notifies the outgoing task by passing the incoming.
+	 * are going on and notifies the active task by passing the passive.
 	 *
-	 * @param other		incoming task
+	 * @param other		passive task (adopted)
 	 */
 	void (*collide)(child_rekey_t* this, task_t *other);
 };
@@ -59,6 +72,6 @@ struct child_rekey_t {
  * @return				child_rekey task to handle by the task_manager
  */
 child_rekey_t *child_rekey_create(ike_sa_t *ike_sa, protocol_id_t protocol,
-								  u_int32_t spi);
+								  uint32_t spi);
 
 #endif /** CHILD_REKEY_H_ @}*/
diff --git a/src/libcharon/sa/ikev2/tasks/ike_auth.c b/src/libcharon/sa/ikev2/tasks/ike_auth.c
index 79a436fbf..036910d0e 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_auth.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_auth.c
@@ -186,7 +186,7 @@ static status_t collect_other_init_data(private_ike_auth_t *this,
  */
 static void get_reserved_id_bytes(private_ike_auth_t *this, id_payload_t *id)
 {
-	u_int8_t *byte;
+	uint8_t *byte;
 	int i;
 
 	for (i = 0; i < countof(this->reserved); i++)
@@ -564,6 +564,10 @@ METHOD(task_t, process_r, status_t,
 			this->ike_sa->enable_extension(this->ike_sa,
 										   EXT_EAP_ONLY_AUTHENTICATION);
 		}
+		if (message->get_notify(message, INITIAL_CONTACT))
+		{
+			this->initial_contact = TRUE;
+		}
 	}
 
 	if (this->other_auth == NULL)
@@ -652,14 +656,6 @@ METHOD(task_t, process_r, status_t,
 			return NEED_MORE;
 	}
 
-	/* If authenticated (with non-EAP) and received INITIAL_CONTACT,
-	 * delete any existing IKE_SAs with that peer. */
-	if (message->get_message_id(message) == 1 &&
-		message->get_notify(message, INITIAL_CONTACT))
-	{
-		this->initial_contact = TRUE;
-	}
-
 	/* another auth round done, invoke authorize hook */
 	if (!charon->bus->authorize(charon->bus, FALSE))
 	{
@@ -749,13 +745,6 @@ METHOD(task_t, build_r, status_t,
 		get_reserved_id_bytes(this, id_payload);
 		message->add_payload(message, (payload_t*)id_payload);
 
-		if (this->initial_contact)
-		{
-			charon->ike_sa_manager->check_uniqueness(charon->ike_sa_manager,
-													 this->ike_sa, TRUE);
-			this->initial_contact = FALSE;
-		}
-
 		if ((uintptr_t)cfg->get(cfg, AUTH_RULE_AUTH_CLASS) == AUTH_CLASS_EAP)
 		{	/* EAP-only authentication */
 			if (!this->ike_sa->supports_extension(this->ike_sa,
@@ -830,7 +819,7 @@ METHOD(task_t, build_r, status_t,
 	}
 
 	if (charon->ike_sa_manager->check_uniqueness(charon->ike_sa_manager,
-												 this->ike_sa, FALSE))
+										this->ike_sa, this->initial_contact))
 	{
 		DBG1(DBG_IKE, "cancelling IKE_SA setup due to uniqueness policy");
 		charon->bus->alert(charon->bus, ALERT_UNIQUE_KEEP);
diff --git a/src/libcharon/sa/ikev2/tasks/ike_auth_lifetime.c b/src/libcharon/sa/ikev2/tasks/ike_auth_lifetime.c
index a7d162e68..47b0a3ed1 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_auth_lifetime.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_auth_lifetime.c
@@ -45,14 +45,14 @@ struct private_ike_auth_lifetime_t {
 static void add_auth_lifetime(private_ike_auth_lifetime_t *this, message_t *message)
 {
 	chunk_t chunk;
-	u_int32_t lifetime;
+	uint32_t lifetime;
 
 	lifetime = this->ike_sa->get_statistic(this->ike_sa, STAT_REAUTH);
 	if (lifetime)
 	{
 		lifetime -= time_monotonic(NULL);
 		chunk = chunk_from_thing(lifetime);
-		*(u_int32_t*)chunk.ptr = htonl(lifetime);
+		*(uint32_t*)chunk.ptr = htonl(lifetime);
 		message->add_notify(message, FALSE, AUTH_LIFETIME, chunk);
 	}
 }
@@ -64,13 +64,13 @@ static void process_payloads(private_ike_auth_lifetime_t *this, message_t *messa
 {
 	notify_payload_t *notify;
 	chunk_t data;
-	u_int32_t lifetime;
+	uint32_t lifetime;
 
 	notify = message->get_notify(message, AUTH_LIFETIME);
 	if (notify)
 	{
 		data = notify->get_notification_data(notify);
-		lifetime = ntohl(*(u_int32_t*)data.ptr);
+		lifetime = ntohl(*(uint32_t*)data.ptr);
 		this->ike_sa->set_auth_lifetime(this->ike_sa, lifetime);
 	}
 }
diff --git a/src/libcharon/sa/ikev2/tasks/ike_delete.c b/src/libcharon/sa/ikev2/tasks/ike_delete.c
index e972dba07..fd36b144a 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_delete.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_delete.c
@@ -1,6 +1,7 @@
 /*
+ * Copyright (C) 2016 Tobias Brunner
  * Copyright (C) 2006-2007 Martin Willi
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -17,7 +18,7 @@
 
 #include <daemon.h>
 #include <encoding/payloads/delete_payload.h>
-
+#include <sa/ikev2/tasks/ike_rekey.h>
 
 typedef struct private_ike_delete_t private_ike_delete_t;
 
@@ -45,11 +46,6 @@ struct private_ike_delete_t {
 	 * are we deleting a rekeyed SA?
 	 */
 	bool rekeyed;
-
-	/**
-	 * are we responding to a delete, but have initated our own?
-	 */
-	bool simultaneous;
 };
 
 METHOD(task_t, build_i, status_t,
@@ -68,7 +64,8 @@ METHOD(task_t, build_i, status_t,
 	delete_payload = delete_payload_create(PLV2_DELETE, PROTO_IKE);
 	message->add_payload(message, (payload_t*)delete_payload);
 
-	if (this->ike_sa->get_state(this->ike_sa) == IKE_REKEYING)
+	if (this->ike_sa->get_state(this->ike_sa) == IKE_REKEYING ||
+		this->ike_sa->get_state(this->ike_sa) == IKE_REKEYED)
 	{
 		this->rekeyed = TRUE;
 	}
@@ -93,6 +90,33 @@ METHOD(task_t, process_i, status_t,
 	return DESTROY_ME;
 }
 
+/**
+ * Check if this delete happened after a rekey collsion
+ */
+static bool after_rekey_collision(private_ike_delete_t *this)
+{
+	enumerator_t *tasks;
+	task_t *task;
+
+	tasks = this->ike_sa->create_task_enumerator(this->ike_sa,
+												 TASK_QUEUE_ACTIVE);
+	while (tasks->enumerate(tasks, &task))
+	{
+		if (task->get_type(task) == TASK_IKE_REKEY)
+		{
+			ike_rekey_t *rekey = (ike_rekey_t*)task;
+
+			if (rekey->did_collide(rekey))
+			{
+				tasks->destroy(tasks);
+				return TRUE;
+			}
+		}
+	}
+	tasks->destroy(tasks);
+	return FALSE;
+}
+
 METHOD(task_t, process_r, status_t,
 	private_ike_delete_t *this, message_t *message)
 {
@@ -119,16 +143,24 @@ METHOD(task_t, process_r, status_t,
 
 	switch (this->ike_sa->get_state(this->ike_sa))
 	{
+		case IKE_REKEYING:
+			/* if the peer concurrently deleted the IKE_SA we treat this as
+			 * regular delete.  however, in case the peer did not detect a rekey
+			 * collision it will delete the replaced IKE_SA if we are still in
+			 * state IKE_REKEYING */
+			if (after_rekey_collision(this))
+			{
+				this->rekeyed = TRUE;
+				break;
+			}
+			/* fall-through */
 		case IKE_ESTABLISHED:
 			this->ike_sa->set_state(this->ike_sa, IKE_DELETING);
 			this->ike_sa->reestablish(this->ike_sa);
 			return NEED_MORE;
-		case IKE_REKEYING:
+		case IKE_REKEYED:
 			this->rekeyed = TRUE;
 			break;
-		case IKE_DELETING:
-			this->simultaneous = TRUE;
-			break;
 		default:
 			break;
 	}
@@ -141,11 +173,6 @@ METHOD(task_t, build_r, status_t,
 {
 	DBG0(DBG_IKE, "IKE_SA deleted");
 
-	if (this->simultaneous)
-	{
-		/* wait for peer's response for our delete request */
-		return SUCCESS;
-	}
 	if (!this->rekeyed)
 	{	/* invoke ike_down() hook if SA has not been rekeyed */
 		charon->bus->ike_updown(charon->bus, this->ike_sa, FALSE);
@@ -164,7 +191,6 @@ METHOD(task_t, migrate, void,
 	private_ike_delete_t *this, ike_sa_t *ike_sa)
 {
 	this->ike_sa = ike_sa;
-	this->simultaneous = FALSE;
 }
 
 METHOD(task_t, destroy, void,
diff --git a/src/libcharon/sa/ikev2/tasks/ike_init.c b/src/libcharon/sa/ikev2/tasks/ike_init.c
index 78579be95..801b6d8f3 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_init.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_init.c
@@ -221,7 +221,7 @@ static void handle_supported_hash_algorithms(private_ike_init_t *this,
 											 notify_payload_t *notify)
 {
 	bio_reader_t *reader;
-	u_int16_t algo;
+	uint16_t algo;
 	bool added = FALSE;
 
 	reader = bio_reader_create(notify->get_notification_data(notify));
@@ -373,13 +373,15 @@ static void process_payloads(private_ike_init_t *this, message_t *message)
 			{
 				sa_payload_t *sa_payload = (sa_payload_t*)payload;
 				linked_list_t *proposal_list;
-				bool private;
+				bool private, prefer_configured;
 
 				proposal_list = sa_payload->get_proposals(sa_payload);
 				private = this->ike_sa->supports_extension(this->ike_sa,
 														   EXT_STRONGSWAN);
+				prefer_configured = lib->settings->get_bool(lib->settings,
+							"%s.prefer_configured_proposals", TRUE, lib->ns);
 				this->proposal = this->config->select_proposal(this->config,
-														proposal_list, private);
+									proposal_list, private, prefer_configured);
 				if (!this->proposal)
 				{
 					charon->bus->alert(charon->bus, ALERT_PROPOSAL_MISMATCH_IKE,
@@ -633,7 +635,7 @@ METHOD(task_t, build_r, status_t,
 	if (this->dh == NULL ||
 		!this->proposal->has_dh_group(this->proposal, this->dh_group))
 	{
-		u_int16_t group;
+		uint16_t group;
 
 		if (this->proposal->get_algorithm(this->proposal, DIFFIE_HELLMAN_GROUP,
 										  &group, NULL))
@@ -765,7 +767,7 @@ METHOD(task_t, process_i, status_t,
 
 					bad_group = this->dh_group;
 					data = notify->get_notification_data(notify);
-					this->dh_group = ntohs(*((u_int16_t*)data.ptr));
+					this->dh_group = ntohs(*((uint16_t*)data.ptr));
 					DBG1(DBG_IKE, "peer didn't accept DH group %N, "
 						 "it requested %N", diffie_hellman_group_names,
 						 bad_group, diffie_hellman_group_names, this->dh_group);
diff --git a/src/libcharon/sa/ikev2/tasks/ike_me.c b/src/libcharon/sa/ikev2/tasks/ike_me.c
index 10d412ffd..f077ccfb5 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_me.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_me.c
@@ -128,7 +128,7 @@ static void gather_and_add_endpoints(private_ike_me_t *this, message_t *message)
 {
 	enumerator_t *enumerator;
 	host_t *addr, *host;
-	u_int16_t port;
+	uint16_t port;
 
 	/* get the port that is used to communicate with the ms */
 	host = this->ike_sa->get_my_host(this->ike_sa);
diff --git a/src/libcharon/sa/ikev2/tasks/ike_mobike.c b/src/libcharon/sa/ikev2/tasks/ike_mobike.c
index 3f7bb175f..dc0f24fb8 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_mobike.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_mobike.c
@@ -299,7 +299,7 @@ static void update_children(private_ike_mobike_t *this)
 /**
  * Apply the port of the old host, if its ip equals the new, use port otherwise.
  */
-static void apply_port(host_t *host, host_t *old, u_int16_t port, bool local)
+static void apply_port(host_t *host, host_t *old, uint16_t port, bool local)
 {
 	if (host->ip_equals(host, old))
 	{
diff --git a/src/libcharon/sa/ikev2/tasks/ike_natd.c b/src/libcharon/sa/ikev2/tasks/ike_natd.c
index 4bf5264dd..f3f32d7af 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_natd.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_natd.c
@@ -99,8 +99,8 @@ static chunk_t generate_natd_hash(private_ike_natd_t *this,
 {
 	chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk;
 	chunk_t natd_hash;
-	u_int64_t spi_i, spi_r;
-	u_int16_t port;
+	uint64_t spi_i, spi_r;
+	uint16_t port;
 
 	/* prepare all required chunks */
 	spi_i = ike_sa_id->get_initiator_spi(ike_sa_id);
@@ -142,7 +142,7 @@ static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
 	config = this->ike_sa->get_ike_cfg(this->ike_sa);
 	if (force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
 	{
-		u_int32_t addr;
+		uint32_t addr;
 
 		/* chunk_hash() is randomly keyed so this produces a random IPv4 address
 		 * that changes with every restart but otherwise stays the same */
diff --git a/src/libcharon/sa/ikev2/tasks/ike_rekey.c b/src/libcharon/sa/ikev2/tasks/ike_rekey.c
index eaba04e3a..2f0552a33 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_rekey.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_rekey.c
@@ -1,7 +1,8 @@
 /*
+ * Copyright (C) 2015-2016 Tobias Brunner
  * Copyright (C) 2005-2008 Martin Willi
  * Copyright (C) 2005 Jan Hutter
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -66,9 +67,30 @@ struct private_ike_rekey_t {
 	 * colliding task detected by the task manager
 	 */
 	task_t *collision;
+
+	/**
+	 * TRUE if rekeying can't be handled temporarily
+	 */
+	bool failed_temporarily;
 };
 
 /**
+ * Schedule a retry if rekeying temporary failed
+ */
+static void schedule_delayed_rekey(private_ike_rekey_t *this)
+{
+	uint32_t retry;
+	job_t *job;
+
+	retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
+	job = (job_t*)rekey_ike_sa_job_create(
+						this->ike_sa->get_id(this->ike_sa), FALSE);
+	DBG1(DBG_IKE, "IKE_SA rekeying failed, trying again in %d seconds", retry);
+	this->ike_sa->set_state(this->ike_sa, IKE_ESTABLISHED);
+	lib->scheduler->schedule_job(lib->scheduler, job, retry);
+}
+
+/**
  * Check if an IKE_SA has any queued tasks, return initiation job
  */
 static job_t* check_queued_tasks(ike_sa_t *ike_sa)
@@ -83,7 +105,6 @@ static job_t* check_queued_tasks(ike_sa_t *ike_sa)
 		job = (job_t*)initiate_tasks_job_create(ike_sa->get_id(ike_sa));
 	}
 	enumerator->destroy(enumerator);
-
 	return job;
 }
 
@@ -117,20 +138,9 @@ static void establish_new(private_ike_rekey_t *this)
 		}
 		this->new_sa = NULL;
 		charon->bus->set_sa(charon->bus, this->ike_sa);
-	}
-}
 
-METHOD(task_t, process_r_delete, status_t,
-	private_ike_rekey_t *this, message_t *message)
-{
-	establish_new(this);
-	return this->ike_delete->task.process(&this->ike_delete->task, message);
-}
-
-METHOD(task_t, build_r_delete, status_t,
-	private_ike_rekey_t *this, message_t *message)
-{
-	return this->ike_delete->task.build(&this->ike_delete->task, message);
+		this->ike_sa->set_state(this->ike_sa, IKE_REKEYED);
+	}
 }
 
 METHOD(task_t, build_i_delete, status_t,
@@ -172,36 +182,59 @@ METHOD(task_t, build_i, status_t,
 	return NEED_MORE;
 }
 
-METHOD(task_t, process_r, status_t,
-	private_ike_rekey_t *this, message_t *message)
+/**
+ * Check if there are any half-open children
+ */
+static bool have_half_open_children(private_ike_rekey_t *this)
 {
 	enumerator_t *enumerator;
 	child_sa_t *child_sa;
-
-	if (this->ike_sa->get_state(this->ike_sa) == IKE_DELETING)
-	{
-		DBG1(DBG_IKE, "peer initiated rekeying, but we are deleting");
-		return NEED_MORE;
-	}
+	task_t *task;
 
 	enumerator = this->ike_sa->create_child_sa_enumerator(this->ike_sa);
 	while (enumerator->enumerate(enumerator, (void**)&child_sa))
 	{
 		switch (child_sa->get_state(child_sa))
 		{
-			case CHILD_CREATED:
 			case CHILD_REKEYING:
 			case CHILD_RETRYING:
 			case CHILD_DELETING:
-				/* we do not allow rekeying while we have children in-progress */
-				DBG1(DBG_IKE, "peer initiated rekeying, but a child is half-open");
 				enumerator->destroy(enumerator);
-				return NEED_MORE;
+				return TRUE;
 			default:
 				break;
 		}
 	}
 	enumerator->destroy(enumerator);
+	enumerator = this->ike_sa->create_task_enumerator(this->ike_sa,
+													  TASK_QUEUE_ACTIVE);
+	while (enumerator->enumerate(enumerator, (void**)&task))
+	{
+		if (task->get_type(task) == TASK_CHILD_CREATE)
+		{
+			enumerator->destroy(enumerator);
+			return TRUE;
+		}
+	}
+	enumerator->destroy(enumerator);
+	return FALSE;
+}
+
+METHOD(task_t, process_r, status_t,
+	private_ike_rekey_t *this, message_t *message)
+{
+	if (this->ike_sa->get_state(this->ike_sa) == IKE_DELETING)
+	{
+		DBG1(DBG_IKE, "peer initiated rekeying, but we are deleting");
+		this->failed_temporarily = TRUE;
+		return NEED_MORE;
+	}
+	if (have_half_open_children(this))
+	{
+		DBG1(DBG_IKE, "peer initiated rekeying, but a child is half-open");
+		this->failed_temporarily = TRUE;
+		return NEED_MORE;
+	}
 
 	this->new_sa = charon->ike_sa_manager->checkout_new(charon->ike_sa_manager,
 							this->ike_sa->get_version(this->ike_sa), FALSE);
@@ -219,33 +252,57 @@ METHOD(task_t, process_r, status_t,
 METHOD(task_t, build_r, status_t,
 	private_ike_rekey_t *this, message_t *message)
 {
+	if (this->failed_temporarily)
+	{
+		message->add_notify(message, TRUE, TEMPORARY_FAILURE, chunk_empty);
+		return SUCCESS;
+	}
 	if (this->new_sa == NULL)
 	{
 		/* IKE_SA/a CHILD_SA is in an inacceptable state, deny rekeying */
 		message->add_notify(message, TRUE, NO_PROPOSAL_CHOSEN, chunk_empty);
 		return SUCCESS;
 	}
-
 	if (this->ike_init->task.build(&this->ike_init->task, message) == FAILED)
 	{
+		this->ike_init->task.destroy(&this->ike_init->task);
+		this->ike_init = NULL;
 		charon->bus->set_sa(charon->bus, this->ike_sa);
 		return SUCCESS;
 	}
 	charon->bus->set_sa(charon->bus, this->ike_sa);
-	this->ike_sa->set_state(this->ike_sa, IKE_REKEYING);
 
-	/* rekeying successful, delete the IKE_SA using a subtask */
-	this->ike_delete = ike_delete_create(this->ike_sa, FALSE);
-	this->public.task.build = _build_r_delete;
-	this->public.task.process = _process_r_delete;
-
-	/* the peer does have to delete the IKE_SA. If it does not, we get a
-	 * unusable IKE_SA in REKEYING state without a replacement. We consider
-	 * this a timeout condition by the peer, and trigger a delete actively. */
-	lib->scheduler->schedule_job(lib->scheduler, (job_t*)
-		delete_ike_sa_job_create(this->ike_sa->get_id(this->ike_sa), TRUE), 90);
+	if (this->ike_sa->get_state(this->ike_sa) != IKE_REKEYING)
+	{	/* in case of a collision we let the initiating task handle this */
+		establish_new(this);
+		/* make sure the IKE_SA is gone in case the peer fails to delete it */
+		lib->scheduler->schedule_job(lib->scheduler, (job_t*)
+			delete_ike_sa_job_create(this->ike_sa->get_id(this->ike_sa), TRUE),
+									 90);
+	}
+	return SUCCESS;
+}
 
-	return NEED_MORE;
+/**
+ * Conclude any undetected rekey collision.
+ *
+ * If the peer does not detect the collision it will delete this IKE_SA.
+ * Depending on when our request reaches the peer and we receive the delete
+ * this may get called at different times.
+ *
+ * Returns TRUE if there was a collision, FALSE otherwise.
+ */
+static bool conclude_undetected_collision(private_ike_rekey_t *this)
+{
+	if (this->collision &&
+		this->collision->get_type(this->collision) == TASK_IKE_REKEY)
+	{
+		DBG1(DBG_IKE, "peer did not notice IKE_SA rekey collision, abort "
+			 "active rekeying");
+		establish_new((private_ike_rekey_t*)this->collision);
+		return TRUE;
+	}
+	return FALSE;
 }
 
 METHOD(task_t, process_i, status_t,
@@ -266,18 +323,9 @@ METHOD(task_t, process_i, status_t,
 	{
 		case FAILED:
 			/* rekeying failed, fallback to old SA */
-			if (!(this->collision && (
-				this->collision->get_type(this->collision) == TASK_IKE_DELETE ||
-				this->collision->get_type(this->collision) == TASK_IKE_REAUTH)))
+			if (!conclude_undetected_collision(this))
 			{
-				job_t *job;
-				u_int32_t retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
-				job = (job_t*)rekey_ike_sa_job_create(
-										this->ike_sa->get_id(this->ike_sa), FALSE);
-				DBG1(DBG_IKE, "IKE_SA rekeying failed, "
-										"trying again in %d seconds", retry);
-				this->ike_sa->set_state(this->ike_sa, IKE_ESTABLISHED);
-				lib->scheduler->schedule_job(lib->scheduler, job, retry);
+				schedule_delayed_rekey(this);
 			}
 			return SUCCESS;
 		case NEED_MORE:
@@ -293,55 +341,53 @@ METHOD(task_t, process_i, status_t,
 		this->collision->get_type(this->collision) == TASK_IKE_REKEY)
 	{
 		private_ike_rekey_t *other = (private_ike_rekey_t*)this->collision;
+		host_t *host;
+		chunk_t this_nonce, other_nonce;
 
-		/* ike_init can be NULL, if child_sa is half-open */
-		if (other->ike_init)
-		{
-			host_t *host;
-			chunk_t this_nonce, other_nonce;
-
-			this_nonce = this->ike_init->get_lower_nonce(this->ike_init);
-			other_nonce = other->ike_init->get_lower_nonce(other->ike_init);
+		this_nonce = this->ike_init->get_lower_nonce(this->ike_init);
+		other_nonce = other->ike_init->get_lower_nonce(other->ike_init);
 
-			/* if we have the lower nonce, delete rekeyed SA. If not, delete
-			 * the redundant. */
-			if (memcmp(this_nonce.ptr, other_nonce.ptr,
-						min(this_nonce.len, other_nonce.len)) > 0)
+		/* if we have the lower nonce, delete rekeyed SA. If not, delete
+		 * the redundant. */
+		if (memcmp(this_nonce.ptr, other_nonce.ptr,
+				   min(this_nonce.len, other_nonce.len)) < 0)
+		{
+			DBG1(DBG_IKE, "IKE_SA rekey collision lost, deleting redundant "
+				 "IKE_SA %s[%d]", this->new_sa->get_name(this->new_sa),
+				 this->new_sa->get_unique_id(this->new_sa));
+			/* apply host for a proper delete */
+			host = this->ike_sa->get_my_host(this->ike_sa);
+			this->new_sa->set_my_host(this->new_sa, host->clone(host));
+			host = this->ike_sa->get_other_host(this->ike_sa);
+			this->new_sa->set_other_host(this->new_sa, host->clone(host));
+			/* IKE_SAs in state IKE_REKEYED are silently deleted, so we use
+			 * IKE_REKEYING */
+			this->new_sa->set_state(this->new_sa, IKE_REKEYING);
+			if (this->new_sa->delete(this->new_sa) == DESTROY_ME)
 			{
-				/* peer should delete this SA. Add a timeout just in case. */
-				job_t *job = (job_t*)delete_ike_sa_job_create(
-						other->new_sa->get_id(other->new_sa), TRUE);
-				lib->scheduler->schedule_job(lib->scheduler, job, 10);
-				DBG1(DBG_IKE, "IKE_SA rekey collision won, waiting for delete");
-				charon->ike_sa_manager->checkin(charon->ike_sa_manager, other->new_sa);
-				other->new_sa = NULL;
+				this->new_sa->destroy(this->new_sa);
 			}
 			else
 			{
-				DBG1(DBG_IKE, "IKE_SA rekey collision lost, "
-					 "deleting redundant IKE_SA");
-				/* apply host for a proper delete */
-				host = this->ike_sa->get_my_host(this->ike_sa);
-				this->new_sa->set_my_host(this->new_sa, host->clone(host));
-				host = this->ike_sa->get_other_host(this->ike_sa);
-				this->new_sa->set_other_host(this->new_sa, host->clone(host));
-				this->ike_sa->set_state(this->ike_sa, IKE_ESTABLISHED);
-				this->new_sa->set_state(this->new_sa, IKE_REKEYING);
-				if (this->new_sa->delete(this->new_sa) == DESTROY_ME)
-				{
-					this->new_sa->destroy(this->new_sa);
-				}
-				else
-				{
-					charon->ike_sa_manager->checkin(
-								charon->ike_sa_manager, this->new_sa);
-				}
-				charon->bus->set_sa(charon->bus, this->ike_sa);
-				this->new_sa = NULL;
-				establish_new(other);
-				return SUCCESS;
+				charon->ike_sa_manager->checkin(charon->ike_sa_manager,
+												this->new_sa);
 			}
+			charon->bus->set_sa(charon->bus, this->ike_sa);
+			this->new_sa = NULL;
+			establish_new(other);
+			return SUCCESS;
 		}
+		/* peer should delete this SA. Add a timeout just in case. */
+		job_t *job = (job_t*)delete_ike_sa_job_create(
+									other->new_sa->get_id(other->new_sa), TRUE);
+		lib->scheduler->schedule_job(lib->scheduler, job,
+									 HALF_OPEN_IKE_SA_TIMEOUT);
+		DBG1(DBG_IKE, "IKE_SA rekey collision won, waiting for delete for "
+			 "redundant IKE_SA %s[%d]", other->new_sa->get_name(other->new_sa),
+			 other->new_sa->get_unique_id(other->new_sa));
+		other->new_sa->set_state(other->new_sa, IKE_REKEYED);
+		charon->ike_sa_manager->checkin(charon->ike_sa_manager, other->new_sa);
+		other->new_sa = NULL;
 		charon->bus->set_sa(charon->bus, this->ike_sa);
 	}
 
@@ -361,11 +407,41 @@ METHOD(task_t, get_type, task_type_t,
 	return TASK_IKE_REKEY;
 }
 
+METHOD(ike_rekey_t, did_collide, bool,
+	private_ike_rekey_t *this)
+{
+	return this->collision &&
+		   this->collision->get_type(this->collision) == TASK_IKE_REKEY;
+}
+
 METHOD(ike_rekey_t, collide, void,
 	private_ike_rekey_t* this, task_t *other)
 {
 	DBG1(DBG_IKE, "detected %N collision with %N", task_type_names,
 		 TASK_IKE_REKEY, task_type_names, other->get_type(other));
+
+	switch (other->get_type(other))
+	{
+		case TASK_IKE_DELETE:
+			conclude_undetected_collision(this);
+			other->destroy(other);
+			return;
+		case TASK_IKE_REKEY:
+		{
+			private_ike_rekey_t *rekey = (private_ike_rekey_t*)other;
+
+			if (!rekey->ike_init)
+			{
+				DBG1(DBG_IKE, "colliding exchange did not result in an IKE_SA, "
+					 "ignore");
+				other->destroy(other);
+				return;
+			}
+			break;
+		}
+		default:
+			break;
+	}
 	DESTROY_IF(this->collision);
 	this->collision = other;
 }
@@ -425,6 +501,7 @@ ike_rekey_t *ike_rekey_create(ike_sa_t *ike_sa, bool initiator)
 				.migrate = _migrate,
 				.destroy = _destroy,
 			},
+			.did_collide = _did_collide,
 			.collide = _collide,
 		},
 		.ike_sa = ike_sa,
diff --git a/src/libcharon/sa/ikev2/tasks/ike_rekey.h b/src/libcharon/sa/ikev2/tasks/ike_rekey.h
index 6a12e9034..86b512c92 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_rekey.h
+++ b/src/libcharon/sa/ikev2/tasks/ike_rekey.h
@@ -1,6 +1,7 @@
 /*
+ * Copyright (C) 2016 Tobias Brunner
  * Copyright (C) 2007 Martin Willi
- * Hochschule fuer Technik Rapperswil
+ * HSR 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
@@ -38,6 +39,13 @@ struct ike_rekey_t {
 	task_t task;
 
 	/**
+	 * Check if there was a rekey collision.
+	 *
+	 * @return			TRUE if there was a rekey collision before
+	 */
+	bool (*did_collide)(ike_rekey_t *this);
+
+	/**
 	 * Register a rekeying task which collides with this one.
 	 *
 	 * If two peers initiate rekeying at the same time, the collision must