Callback for ESP packets added to receiver.

src/libcharon/network/receiver.c

@@ -27,6 +27,7 @@
 #include <processing/jobs/process_message_job.h>
 #include <processing/jobs/callback_job.h>
 #include <crypto/hashers/hasher.h>
+#include <threading/mutex.h>
 
 /** lifetime of a cookie, in seconds */
 #define COOKIE_LIFETIME 10
@@ -54,6 +55,19 @@ struct private_receiver_t {
 	 */
 	receiver_t public;
 
+	/**
+	 * Registered callback for ESP packets
+	 */
+	struct {
+		receiver_esp_cb_t cb;
+		void *data;
+	} esp_cb;
+
+	/**
+	 * Mutex for ESP callback
+	 */
+	mutex_t *esp_cb_mutex;
+
 	/**
 	 * current secret to use for cookie calculation
 	 */
@@ -433,7 +447,16 @@ static job_requeue_t receive_packets(private_receiver_t *this)
 		}
 		else
 		{	/* this seems to be an ESP packet */
-			packet->destroy(packet);
+			this->esp_cb_mutex->lock(this->esp_cb_mutex);
+			if (this->esp_cb.cb)
+			{
+				this->esp_cb.cb(this->esp_cb.data, packet);
+			}
+			else
+			{
+				packet->destroy(packet);
+			}
+			this->esp_cb_mutex->unlock(this->esp_cb_mutex);
 			return JOB_REQUEUE_DIRECT;
 		}
 	}
@@ -536,11 +559,33 @@ static job_requeue_t receive_packets(private_receiver_t *this)
 	return JOB_REQUEUE_DIRECT;
 }
 
+METHOD(receiver_t, add_esp_cb, void,
+	private_receiver_t *this, receiver_esp_cb_t callback, void *data)
+{
+	this->esp_cb_mutex->lock(this->esp_cb_mutex);
+	this->esp_cb.cb = callback;
+	this->esp_cb.data = data;
+	this->esp_cb_mutex->unlock(this->esp_cb_mutex);
+}
+
+METHOD(receiver_t, del_esp_cb, void,
+	private_receiver_t *this, receiver_esp_cb_t callback)
+{
+	this->esp_cb_mutex->lock(this->esp_cb_mutex);
+	if (this->esp_cb.cb == callback)
+	{
+		this->esp_cb.cb = NULL;
+		this->esp_cb.data = NULL;
+	}
+	this->esp_cb_mutex->unlock(this->esp_cb_mutex);
+}
+
 METHOD(receiver_t, destroy, void,
 	private_receiver_t *this)
 {
 	this->rng->destroy(this->rng);
 	this->hasher->destroy(this->hasher);
+	this->esp_cb_mutex->destroy(this->esp_cb_mutex);
 	free(this);
 }
 
@@ -554,8 +599,11 @@ receiver_t *receiver_create()
 
 	INIT(this,
 		.public = {
+			.add_esp_cb = _add_esp_cb,
+			.del_esp_cb = _del_esp_cb,
 			.destroy = _destroy,
 		},
+		.esp_cb_mutex = mutex_create(MUTEX_TYPE_DEFAULT),
 		.secret_switch = now,
 		.secret_offset = random() % now,
 	);

src/libcharon/network/receiver.h

@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2012 Tobias Brunner
  * Copyright (C) 2005-2007 Martin Willi
  * Copyright (C) 2005 Jan Hutter
  * Hochschule fuer Technik Rapperswil
@@ -25,15 +26,28 @@
 typedef struct receiver_t receiver_t;
 
 #include <library.h>
+#include <network/packet.h>
 #include <utils/host.h>
 
+/**
+ * Callback called for any received UDP encapsulated ESP packet.
+ *
+ * Implementation should be quick as the receiver doesn't receive any packets
+ * while calling this function.
+ *
+ * @param data			data supplied during registration of the callback
+ * @param packet		decapsulated ESP packet
+ */
+typedef void (*receiver_esp_cb_t)(void *data, packet_t *packet);
+
 /**
  * Receives packets from the socket and adds them to the job queue.
  *
- * The receiver starts a thread, which reads on the blocking socket. A received
- * packet is preparsed and a process_message_job is queued in the job queue.
+ * The receiver uses a callback job, which reads on the blocking socket.
+ * A received packet is preparsed and a process_message_job is queued in the
+ * job queue.
  *
- * To endure DoS attacks, cookies are enabled when to many IKE_SAs are half
+ * To endure DoS attacks, cookies are enabled when too many IKE_SAs are half
  * open. The calculation of cookies is slightly different from the proposed
  * method in RFC4306. We do not include a nonce, because we think the advantage
  * we gain does not justify the overhead to parse the whole message.
@@ -47,14 +61,32 @@ typedef struct receiver_t receiver_t;
  * secret is stored to allow a clean migration between secret changes.
  *
  * Further, the number of half-initiated IKE_SAs is limited per peer. This
- * mades it impossible for a peer to flood the server with its real IP address.
+ * makes it impossible for a peer to flood the server with its real IP address.
  */
 struct receiver_t {
 
+	/**
+	 * Register a callback which is called for any incoming ESP packets.
+	 *
+	 * @note Only the last callback registered will receive any packets.
+	 *
+	 * @param callback		callback to register
+	 * @param data			data provided to callback
+	 */
+	void (*add_esp_cb)(receiver_t *this, receiver_esp_cb_t callback,
+					   void *data);
+
+	/**
+	 * Unregister a previously registered callback for ESP packets.
+	 *
+	 * @param callback		previously registered callback
+	 */
+	void (*del_esp_cb)(receiver_t *this, receiver_esp_cb_t callback);
+
 	/**
 	 * Destroys a receiver_t object.
 	 */
-	void (*destroy) (receiver_t *receiver);
+	void (*destroy)(receiver_t *this);
 };
 
 /**