From: Tobias Brunner <tobias@strongswan.org>
Date: Tue, 4 Oct 2016 13:15:36 +0000 (+0200)
Subject: ikev2: Don't increase expected MID after handling MID sync message
X-Git-Tag: 5.5.2dr5~22^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c3d98d298ec2238a8a76694587fa1f36b5a1e14c;p=thirdparty%2Fstrongswan.git

ikev2: Don't increase expected MID after handling MID sync message

If the responder never sent a message the expected MID is 0.  While
the sent MID (M1) SHOULD be increased beyond the known value, it's
not necessarily the case.
Since M2 - 1 would then equal UINT_MAX setting that MID would get ignored
and while we'd return 0 in the notify we'd actually expect 1 afterwards.
---

diff --git a/src/libcharon/sa/ikev2/task_manager_v2.c b/src/libcharon/sa/ikev2/task_manager_v2.c
index debfe23fae..778349c08b 100644
--- a/src/libcharon/sa/ikev2/task_manager_v2.c
+++ b/src/libcharon/sa/ikev2/task_manager_v2.c
@@ -918,6 +918,9 @@ static status_t build_response(private_task_manager_t *this, message_t *request)
 		/* we don't want to resend messages to sync MIDs if requests with the
 		 * previous MID arrive */
 		clear_packets(this->responding.packets);
+		/* avoid increasing the expected message ID after handling a message
+		 * to sync MIDs with MID 0 */
+		return NEED_MORE;
 	}
 
 	array_compress(this->passive_tasks);
diff --git a/src/libcharon/sa/ikev2/tasks/ike_mid_sync.c b/src/libcharon/sa/ikev2/tasks/ike_mid_sync.c
index 9967697dd3..d7de113036 100644
--- a/src/libcharon/sa/ikev2/tasks/ike_mid_sync.c
+++ b/src/libcharon/sa/ikev2/tasks/ike_mid_sync.c
@@ -180,9 +180,7 @@ METHOD(task_t, process, status_t,
 	m2 = max(this->send, resp);
 	if (resp != m2)
 	{
-		/* after responding to this message the expected message ID is increased
-		 * by one so we reduce it here */
-		this->ike_sa->set_message_id(this->ike_sa, FALSE, m2 - 1);
+		this->ike_sa->set_message_id(this->ike_sa, FALSE, m2);
 	}
 	init = this->ike_sa->get_message_id(this->ike_sa, TRUE);
 	p2 = max(this->recv, has_active_tasks(this) ? init + 1 : init);