ike: Move fragmentation to ike_sa_t

The message() hook on bus_t is now called exactly once before (plain) and
once after fragmenting (!plain), not twice for the complete message and again
for each individual fragment, as was the case in earlier iterations.

For inbound messages the hook is called once for each fragment (!plain)
and twice for the reassembled message.

src/libcharon/sa/ike_sa.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2006-2012 Tobias Brunner
+ * Copyright (C) 2006-2014 Tobias Brunner
  * Copyright (C) 2006 Daniel Roethlisberger
  * Copyright (C) 2005-2009 Martin Willi
  * Copyright (C) 2005 Jan Hutter
@@ -756,7 +756,7 @@ struct ike_sa_t {
 	status_t (*roam)(ike_sa_t *this, bool address);
 
 	/**
-	 * Processes a incoming IKEv2-Message.
+	 * Processes an incoming IKE message.
 	 *
 	 * Message processing may fail. If a critical failure occurs,
 	 * process_message() return DESTROY_ME. Then the caller must
@@ -768,10 +768,10 @@ struct ike_sa_t {
 	 *						- FAILED
 	 *						- DESTROY_ME if this IKE_SA MUST be deleted
 	 */
-	status_t (*process_message) (ike_sa_t *this, message_t *message);
+	status_t (*process_message)(ike_sa_t *this, message_t *message);
 
 	/**
-	 * Generate a IKE message to send it to the peer.
+	 * Generate an IKE message to send it to the peer.
 	 *
 	 * This method generates all payloads in the message and encrypts/signs
 	 * the packet.
@@ -783,8 +783,26 @@ struct ike_sa_t {
 	 *						- FAILED
 	 *						- DESTROY_ME if this IKE_SA MUST be deleted
 	 */
-	status_t (*generate_message) (ike_sa_t *this, message_t *message,
-								  packet_t **packet);
+	status_t (*generate_message)(ike_sa_t *this, message_t *message,
+								 packet_t **packet);
+
+	/**
+	 * Generate an IKE message to send it to the peer. If enabled and supported
+	 * it will be fragmented.
+	 *
+	 * This method generates all payloads in the message and encrypts/signs
+	 * the packet/fragments.
+	 *
+	 * @param message		message to generate
+	 * @param packets		enumerator of generated packet_t* (are not destroyed
+	 *						with the enumerator)
+	 * @return
+	 *						- SUCCESS
+	 *						- FAILED
+	 *						- DESTROY_ME if this IKE_SA MUST be deleted
+	 */
+	status_t (*generate_message_fragmented)(ike_sa_t *this, message_t *message,
+											enumerator_t **packets);
 
 	/**
 	 * Retransmits a request.