message: Fragment and reassemble IKEv2 messages

2 files changed, 366 insertions, 133 deletions

diff --git a/src/libcharon/encoding/message.c b/src/libcharon/encoding/message.c
index 262f1050b..43f74238f 100644
--- a/src/libcharon/encoding/message.c
+++ b/src/libcharon/encoding/message.c
@@ -33,6 +33,7 @@
 #include <encoding/payloads/payload.h>
 #include <encoding/payloads/hash_payload.h>
 #include <encoding/payloads/encrypted_payload.h>
+#include <encoding/payloads/encrypted_fragment_payload.h>
 #include <encoding/payloads/unknown_payload.h>
 #include <encoding/payloads/cp_payload.h>
 #include <encoding/payloads/fragment_payload.h>
@@ -819,8 +820,9 @@ typedef struct {
 	 * For IKEv1 the number of the last fragment (in case we receive them out
 	 * of order), since the first one starts with 1 this defines the number of
 	 * fragments we expect.
+	 * For IKEv2 we store the total number of fragment we received last.
 	 */
-	u_int8_t last;
+	u_int16_t last;
 
 	/**
 	 * Length of all currently received fragments.
@@ -908,7 +910,7 @@ struct private_message_t {
 
 	/**
 	 * Array of generated fragments (if any), as packet_t*.
-	 * If defragmenting (frag != NULL) this contains fragment_t*
+	 * If defragmenting (i.e. frag != NULL) this contains fragment_t*
 	 */
 	array_t *fragments;
 
@@ -952,11 +954,10 @@ static void fragment_destroy(fragment_t *this)
 	free(this);
 }
 
-static void reset_defrag(private_message_t *this, u_int16_t id)
+static void reset_defrag(private_message_t *this)
 {
 	array_destroy_function(this->fragments, (void*)fragment_destroy, NULL);
 	this->fragments = NULL;
-	this->message_id = id;
 	this->frag->last = 0;
 	this->frag->len = 0;
 }
@@ -1822,35 +1823,64 @@ static message_t *clone_message(private_message_t *this)
 	message->set_source(message, src->clone(src));
 	message->set_destination(message, dst->clone(dst));
 	message->set_exchange_type(message, this->exchange_type);
+	memcpy(((private_message_t*)message)->reserved, this->reserved,
+		   sizeof(this->reserved));
 	return message;
 }
 
 /**
  * Create a single fragment with the given data
  */
-static message_t *create_fragment(private_message_t *this, u_int8_t num,
-								  bool last, chunk_t data)
+static message_t *create_fragment(private_message_t *this, payload_type_t next,
+								  u_int16_t num, u_int16_t count, chunk_t data)
 {
-	fragment_payload_t *fragment;
+	enumerator_t *enumerator;
+	payload_t *fragment, *payload;
 	message_t *message;
 	peer_cfg_t *peer_cfg;
 	ike_sa_t *ike_sa;
 
-	fragment = fragment_payload_create_from_data(num, last, data);
 	message = clone_message(this);
-	/* other implementations seem to just use 0 as message ID, so here we go */
-	message->set_message_id(message, 0);
-	/* always use the initial message type for fragments, even for quick mode
-	 * or transaction messages. */
-	ike_sa = charon->bus->get_sa(charon->bus);
-	if (ike_sa && (peer_cfg = ike_sa->get_peer_cfg(ike_sa)) &&
-		peer_cfg->use_aggressive(peer_cfg))
-	{
-		message->set_exchange_type(message, AGGRESSIVE);
+	if (this->major_version == IKEV1_MAJOR_VERSION)
+	{
+		/* other implementations seem to just use 0 as message ID, so here we go */
+		message->set_message_id(message, 0);
+		/* always use the initial message type for fragments, even for quick mode
+		 * or transaction messages. */
+		ike_sa = charon->bus->get_sa(charon->bus);
+		if (ike_sa && (peer_cfg = ike_sa->get_peer_cfg(ike_sa)) &&
+			peer_cfg->use_aggressive(peer_cfg))
+		{
+			message->set_exchange_type(message, AGGRESSIVE);
+		}
+		else
+		{
+			message->set_exchange_type(message, ID_PROT);
+		}
+		fragment = (payload_t*)fragment_payload_create_from_data(
+													num, num == count, data);
 	}
 	else
 	{
-		message->set_exchange_type(message, ID_PROT);
+		fragment = (payload_t*)encrypted_fragment_payload_create_from_data(
+													num, count, data);
+		if (num == 1)
+		{
+			/* only in the first fragment is this set to the type of the first
+			 * payload in the encrypted payload */
+			fragment->set_next_type(fragment, next);
+			/* move unencrypted payloads to the first fragment */
+			enumerator = this->payloads->create_enumerator(this->payloads);
+			while (enumerator->enumerate(enumerator, &payload))
+			{
+				if (payload->get_type(payload) != PLV2_ENCRYPTED)
+				{
+					this->payloads->remove_at(this->payloads, enumerator);
+					message->add_payload(message, payload);
+				}
+			}
+			enumerator->destroy(enumerator);
+		}
 	}
 	message->add_payload(message, (payload_t*)fragment);
 	return message;
@@ -1869,29 +1899,18 @@ METHOD(message_t, fragment, status_t,
 	private_message_t *this, keymat_t *keymat, size_t frag_len,
 	enumerator_t **fragments)
 {
+	encrypted_payload_t *encrypted = NULL;
+	generator_t *generator = NULL;
 	message_t *fragment;
 	packet_t *packet;
-	u_int8_t num, count;
+	payload_type_t next = PL_NONE;
+	u_int16_t num, count;
 	host_t *src, *dst;
 	chunk_t data;
 	status_t status;
+	u_int32_t *lenpos;
 	size_t len;
 
-	if (this->major_version == IKEV2_MAJOR_VERSION)
-	{
-		return INVALID_STATE;
-	}
-	clear_fragments(this);
-
-	if (!is_encoded(this))
-	{
-		status = generate(this, keymat, NULL);
-		if (status != SUCCESS)
-		{
-			return status;
-		}
-	}
-
 	src = this->packet->get_source(this->packet);
 	dst = this->packet->get_destination(this->packet);
 	if (!frag_len)
@@ -1901,31 +1920,112 @@ METHOD(message_t, fragment, status_t,
 	/* frag_len is the complete IP datagram length, account for overhead (we
 	 * assume no IP options/extension headers are used) */
 	frag_len -= (src->get_family(src) == AF_INET) ? 20 : 40;
-	/* 8 (UDP header) + 28 (IKE header) */
-	frag_len -= 36;
+	/* 8 (UDP header) */
+	frag_len -= 8;
 	if (dst->get_port(dst) != IKEV2_UDP_PORT &&
 		src->get_port(src) != IKEV2_UDP_PORT)
 	{	/* reduce length due to non-ESP marker */
 		frag_len -= 4;
 	}
 
-	data = this->packet->get_data(this->packet);
-	if (data.len <= frag_len)
+	if (is_encoded(this))
 	{
+		if (this->major_version == IKEV2_MAJOR_VERSION)
+		{
+			encrypted = (encrypted_payload_t*)get_payload(this, PLV2_ENCRYPTED);
+		}
+		data = this->packet->get_data(this->packet);
+		len = data.len;
+	}
+	else
+	{
+		status = generate_message(this, keymat, &generator, &encrypted);
+		if (status != SUCCESS)
+		{
+			DESTROY_IF(generator);
+			return status;
+		}
+		data = generator->get_chunk(generator, &lenpos);
+		len = data.len + (encrypted ? encrypted->get_length(encrypted) : 0);
+	}
+
+	/* check if we actually need to fragment the message and if we have an
+	 * encrypted payload for IKEv2 */
+	if (len <= frag_len ||
+	   (this->major_version == IKEV2_MAJOR_VERSION && !encrypted))
+	{
+		if (generator)
+		{
+			status = finalize_message(this, keymat, generator, encrypted);
+			if (status != SUCCESS)
+			{
+				return status;
+			}
+		}
 		*fragments = enumerator_create_single(this->packet, NULL);
 		return SUCCESS;
 	}
-	/* overhead for the fragmentation payload header */
-	frag_len -= 8;
+
+	/* frag_len denoted the maximum IKE message size so far, later on it will
+	 * denote the maximum content size of a fragment payload, therefore,
+	 * account for IKE header */
+	frag_len -= 28;
+
+	if (this->major_version == IKEV1_MAJOR_VERSION)
+	{
+		if (generator)
+		{
+			status = finalize_message(this, keymat, generator, encrypted);
+			if (status != SUCCESS)
+			{
+				return status;
+			}
+			data = this->packet->get_data(this->packet);
+			generator = NULL;
+		}
+		/* overhead for the fragmentation payload header */
+		frag_len -= 8;
+	}
+	else
+	{
+		aead_t *aead;
+
+		if (generator)
+		{
+			generator->destroy(generator);
+			generator = generator_create();
+		}
+		else
+		{	/* do not log again if it was generated previously */
+			generator = generator_create_no_dbg();
+		}
+		next = encrypted->payload_interface.get_next_type((payload_t*)encrypted);
+		encrypted->generate_payloads(encrypted, generator);
+		data = generator->get_chunk(generator, &lenpos);
+		if (!is_encoded(this))
+		{
+			encrypted->destroy(encrypted);
+		}
+		aead = keymat->get_aead(keymat, FALSE);
+		/* overhead for the encrypted fragment payload */
+		frag_len -= aead->get_iv_size(aead) + aead->get_icv_size(aead);
+		frag_len -= 8 /* header */;
+		/* padding and padding length */
+		frag_len = round_down(frag_len, aead->get_block_size(aead)) - 1;
+		/* TODO-FRAG: if there are unencrypted payloads, should we account for
+		 * their length in the first fragment? we still would have to add
+		 * an encrypted fragment payload (albeit empty), even so we couldn't
+		 * prevent IP fragmentation in every case */
+	}
 
 	count = data.len / frag_len + (data.len % frag_len ? 1 : 0);
 	this->fragments = array_create(0, count);
-	DBG2(DBG_ENC, "splitting IKE message with length of %zu bytes into "
-		 "%hhu fragments", data.len, count);
+	DBG1(DBG_ENC, "splitting IKE message with length of %zu bytes into "
+		 "%hu fragments", len, count);
 	for (num = 1; num <= count; num++)
 	{
 		len = min(data.len, frag_len);
-		fragment = create_fragment(this, num, num == count,
+		fragment = create_fragment(this, next, num, count,
 								   chunk_create(data.ptr, len));
 		status = fragment->generate(fragment, keymat, &packet);
 		fragment->destroy(fragment);
@@ -1933,12 +2033,14 @@ METHOD(message_t, fragment, status_t,
 		{
 			DBG1(DBG_ENC, "failed to generate IKE fragment");
 			clear_fragments(this);
+			DESTROY_IF(generator);
 			return FAILED;
 		}
 		array_insert(this->fragments, ARRAY_TAIL, packet);
 		data = chunk_skip(data, len);
 	}
 	*fragments = array_create_enumerator(this->fragments);
+	DESTROY_IF(generator);
 	return SUCCESS;
 }
 
@@ -1970,6 +2072,10 @@ METHOD(message_t, parse_header, status_t,
 
 	DBG2(DBG_ENC, "parsing header of message");
 
+	if (!this->parser)
+	{	/* reassembled IKEv2 message, header is inherited from fragments */
+		return SUCCESS;
+	}
 	this->parser->reset_context(this->parser);
 	status = this->parser->parse_payload(this->parser, PL_HEADER,
 										 (payload_t**)&ike_header);
@@ -2149,43 +2255,52 @@ static status_t decrypt_and_extract(private_message_t *this, keymat_t *keymat,
 		DBG1(DBG_ENC, "found encrypted payload, but no transform set");
 		return INVALID_ARG;
 	}
-	bs = aead->get_block_size(aead);
-	encryption->set_transform(encryption, aead);
-	chunk = this->packet->get_data(this->packet);
-	if (chunk.len < encryption->get_length(encryption) ||
-		chunk.len < bs)
+	if (!this->parser)
 	{
-		DBG1(DBG_ENC, "invalid payload length");
-		return VERIFY_ERROR;
+		/* reassembled IKEv2 messages are already decrypted, we still call
+		 * decrypt() to parse the contained payloads */
+		status = encryption->decrypt(encryption, chunk_empty);
 	}
-	if (keymat->get_version(keymat) == IKEV1)
-	{	/* instead of associated data we provide the IV, we also update
-		 * the IV with the last encrypted block */
-		keymat_v1_t *keymat_v1 = (keymat_v1_t*)keymat;
-		chunk_t iv;
-
-		if (keymat_v1->get_iv(keymat_v1, this->message_id, &iv))
+	else
+	{
+		bs = aead->get_block_size(aead);
+		encryption->set_transform(encryption, aead);
+		chunk = this->packet->get_data(this->packet);
+		if (chunk.len < encryption->get_length(encryption) ||
+			chunk.len < bs)
 		{
-			status = encryption->decrypt(encryption, iv);
-			if (status == SUCCESS)
+			DBG1(DBG_ENC, "invalid payload length");
+			return VERIFY_ERROR;
+		}
+		if (keymat->get_version(keymat) == IKEV1)
+		{	/* instead of associated data we provide the IV, we also update
+			 * the IV with the last encrypted block */
+			keymat_v1_t *keymat_v1 = (keymat_v1_t*)keymat;
+			chunk_t iv;
+
+			if (keymat_v1->get_iv(keymat_v1, this->message_id, &iv))
 			{
-				if (!keymat_v1->update_iv(keymat_v1, this->message_id,
-						chunk_create(chunk.ptr + chunk.len - bs, bs)))
+				status = encryption->decrypt(encryption, iv);
+				if (status == SUCCESS)
 				{
-					status = FAILED;
+					if (!keymat_v1->update_iv(keymat_v1, this->message_id,
+							chunk_create(chunk.ptr + chunk.len - bs, bs)))
+					{
+						status = FAILED;
+					}
 				}
 			}
+			else
+			{
+				status = FAILED;
+			}
 		}
 		else
 		{
-			status = FAILED;
+			chunk.len -= encryption->get_length(encryption);
+			status = encryption->decrypt(encryption, chunk);
 		}
 	}
-	else
-	{
-		chunk.len -= encryption->get_length(encryption);
-		status = encryption->decrypt(encryption, chunk);
-	}
 	if (status != SUCCESS)
 	{
 		return status;
@@ -2432,10 +2547,15 @@ METHOD(message_t, parse_body, status_t,
 		return NOT_SUPPORTED;
 	}
 
-	status = parse_payloads(this);
-	if (status != SUCCESS)
-	{	/* error is already logged */
-		return status;
+	/* reassembled IKEv2 messages are already parsed (except for the payloads
+	 * contained in the encrypted payload, which are handled below) */
+	if (this->parser)
+	{
+		status = parse_payloads(this);
+		if (status != SUCCESS)
+		{	/* error is already logged */
+			return status;
+		}
 	}
 
 	status = decrypt_payloads(this, keymat);
@@ -2500,46 +2620,22 @@ METHOD(message_t, parse_body, status_t,
 	return SUCCESS;
 }
 
-METHOD(message_t, add_fragment, status_t,
-	private_message_t *this, message_t *message)
+/**
+ * Store the fragment data for the fragment with the given fragment number.
+ */
+static status_t add_fragment(private_message_t *this, u_int16_t num,
+							 chunk_t data)
 {
-	fragment_payload_t *payload;
 	fragment_t *fragment;
-	bio_writer_t *writer;
-	host_t *src, *dst;
-	chunk_t data;
-	u_int8_t num;
 	int i, insert_at = -1;
 
-	if (!this->frag)
-	{
-		return INVALID_STATE;
-	}
-	payload = (fragment_payload_t*)message->get_payload(message, PLV1_FRAGMENT);
-	if (!payload)
-	{
-		return INVALID_ARG;
-	}
-	if (!this->fragments || this->message_id != payload->get_id(payload))
-	{
-		reset_defrag(this, payload->get_id(payload));
-		/* we don't know the total number of fragments */
-		this->fragments = array_create(0, 0);
-	}
-
-	num = payload->get_number(payload);
-	if (!this->frag->last && payload->is_last(payload))
-	{
-		this->frag->last = num;
-	}
-
 	for (i = 0; i < array_count(this->fragments); i++)
 	{
 		array_get(this->fragments, i, &fragment);
 		if (fragment->num == num)
 		{
 			/* ignore a duplicate fragment */
-			DBG1(DBG_ENC, "received duplicate fragment #%hhu", num);
+			DBG1(DBG_ENC, "received duplicate fragment #%hu", num);
 			return NEED_MORE;
 		}
 		if (fragment->num > num)
@@ -2548,12 +2644,11 @@ METHOD(message_t, add_fragment, status_t,
 			break;
 		}
 	}
-	data = payload->get_data(payload);
 	this->frag->len += data.len;
 	if (this->frag->len > this->frag->max_packet)
 	{
 		DBG1(DBG_ENC, "fragmented IKE message is too large");
-		reset_defrag(this, 0);
+		reset_defrag(this);
 		return FAILED;
 	}
 	INIT(fragment,
@@ -2561,35 +2656,93 @@ METHOD(message_t, add_fragment, status_t,
 		.data = chunk_clone(data),
 	);
 	array_insert(this->fragments, insert_at, fragment);
+	return SUCCESS;
+}
 
-	if (this->frag->last < array_count(this->fragments))
-	{
-		/* there are some fragments missing */
-		DBG1(DBG_ENC, "received fragment #%hhu, waiting for complete IKE "
-			 "message", num);
-		return NEED_MORE;
-	}
+/**
+ * Merge the cached fragment data and resets the defragmentation state.
+ * Also updates the IP addresses to those of the last received fragment.
+ */
+static chunk_t merge_fragments(private_message_t *this, message_t *last)
+{
+	fragment_t *fragment;
+	bio_writer_t *writer;
+	host_t *src, *dst;
+	chunk_t data;
+	int i;
 
 	writer = bio_writer_create(this->frag->len);
-	DBG1(DBG_ENC, "received fragment #%hhu, reassembling fragmented IKE "
-		 "message", num);
-
 	for (i = 0; i < array_count(this->fragments); i++)
 	{
 		array_get(this->fragments, i, &fragment);
 		writer->write_data(writer, fragment->data);
 	}
-	src = message->get_source(message);
-	dst = message->get_destination(message);
+	data = writer->extract_buf(writer);
+	writer->destroy(writer);
+
+	/* set addresses to those of the last fragment we received */
+	src = last->get_source(last);
+	dst = last->get_destination(last);
 	this->packet->set_source(this->packet, src->clone(src));
 	this->packet->set_destination(this->packet, dst->clone(dst));
-	this->packet->set_data(this->packet, writer->extract_buf(writer));
-	writer->destroy(writer);
-	this->parser->destroy(this->parser);
-	this->parser = parser_create(this->packet->get_data(this->packet));
-	reset_defrag(this, 0);
+
+	reset_defrag(this);
 	free(this->frag);
 	this->frag = NULL;
+	return data;
+}
+
+METHOD(message_t, add_fragment_v1, status_t,
+	private_message_t *this, message_t *message)
+{
+	fragment_payload_t *payload;
+	chunk_t data;
+	u_int8_t num;
+	status_t status;
+
+	if (!this->frag)
+	{
+		return INVALID_STATE;
+	}
+	payload = (fragment_payload_t*)message->get_payload(message, PLV1_FRAGMENT);
+	if (!payload)
+	{
+		return INVALID_ARG;
+	}
+	if (!this->fragments || this->message_id != payload->get_id(payload))
+	{
+		reset_defrag(this);
+		this->message_id = payload->get_id(payload);
+		/* we don't know the total number of fragments, assume something */
+		this->fragments = array_create(0, 4);
+	}
+
+	num = payload->get_number(payload);
+	data = payload->get_data(payload);
+	if (!this->frag->last && payload->is_last(payload))
+	{
+		this->frag->last = num;
+	}
+	status = add_fragment(this, num, data);
+	if (status != SUCCESS)
+	{
+		return status;
+	}
+
+	if (array_count(this->fragments) != this->frag->last)
+	{
+		/* there are some fragments missing */
+		DBG1(DBG_ENC, "received fragment #%hhu, waiting for complete IKE "
+			 "message", num);
+		return NEED_MORE;
+	}
+
+	DBG1(DBG_ENC, "received fragment #%hhu, reassembling fragmented IKE "
+		 "message", num);
+
+	data = merge_fragments(this, message);
+	this->packet->set_data(this->packet, data);
+	this->parser = parser_create(data);
 
 	if (parse_header(this) != SUCCESS)
 	{
@@ -2599,16 +2752,91 @@ METHOD(message_t, add_fragment, status_t,
 	return SUCCESS;
 }
 
+METHOD(message_t, add_fragment_v2, status_t,
+	private_message_t *this, message_t *message)
+{
+	encrypted_fragment_payload_t *encrypted_fragment;
+	encrypted_payload_t *encrypted;
+	payload_t *payload;
+	enumerator_t *enumerator;
+	chunk_t data;
+	u_int16_t total, num;
+	status_t status;
+
+	if (!this->frag)
+	{
+		return INVALID_STATE;
+	}
+	payload = message->get_payload(message, PLV2_FRAGMENT);
+	if (!payload || this->message_id != message->get_message_id(message))
+	{
+		return INVALID_ARG;
+	}
+	encrypted_fragment = (encrypted_fragment_payload_t*)payload;
+	total = encrypted_fragment->get_total_fragments(encrypted_fragment);
+
+	if (!this->fragments || total > this->frag->last)
+	{
+		reset_defrag(this);
+		this->frag->last = total;
+		this->fragments = array_create(0, total);
+	}
+	num = encrypted_fragment->get_fragment_number(encrypted_fragment);
+	data = encrypted_fragment->get_content(encrypted_fragment);
+	status = add_fragment(this, num, data);
+	if (status != SUCCESS)
+	{
+		return status;
+	}
+
+	if (num == 1)
+	{
+		/* the first fragment denotes the payload type of the first payload in
+		 * the original encrypted payload, cache that */
+		this->first_payload = payload->get_next_type(payload);
+		/* move all unencrypted payloads contained in the first fragment */
+		enumerator = message->create_payload_enumerator(message);
+		while (enumerator->enumerate(enumerator, &payload))
+		{
+			if (payload->get_type(payload) != PLV2_FRAGMENT)
+			{
+				message->remove_payload_at(message, enumerator);
+				this->payloads->insert_last(this->payloads, payload);
+			}
+		}
+		enumerator->destroy(enumerator);
+	}
+
+	if (array_count(this->fragments) != total)
+	{
+		/* there are some fragments missing */
+		DBG1(DBG_ENC, "received fragment #%hu of %hu, waiting for complete IKE "
+			 "message", num, total);
+		return NEED_MORE;
+	}
+
+	DBG1(DBG_ENC, "received fragment #%hu of %hu, reassembling fragmented IKE "
+		 "message", num, total);
+
+	data = merge_fragments(this, message);
+	encrypted = encrypted_payload_create_from_plain(this->first_payload, data);
+	this->payloads->insert_last(this->payloads, encrypted);
+	/* update next payload type (could be an unencrypted payload) */
+	this->payloads->get_first(this->payloads, (void**)&payload);
+	this->first_payload = payload->get_type(payload);
+	return SUCCESS;
+}
+
 METHOD(message_t, destroy, void,
 	private_message_t *this)
 {
 	DESTROY_IF(this->ike_sa_id);
+	DESTROY_IF(this->parser);
 	this->payloads->destroy_offset(this->payloads, offsetof(payload_t, destroy));
 	this->packet->destroy(this->packet);
-	this->parser->destroy(this->parser);
 	if (this->frag)
 	{
-		reset_defrag(this, 0);
+		reset_defrag(this);
 		free(this->frag);
 	}
 	else
@@ -2652,7 +2880,7 @@ message_t *message_create_from_packet(packet_t *packet)
 			.is_encoded = _is_encoded,
 			.is_fragmented = _is_fragmented,
 			.fragment = _fragment,
-			.add_fragment = _add_fragment,
+			.add_fragment = _add_fragment_v2,
 			.set_source = _set_source,
 			.get_source = _get_source,
 			.set_destination = _set_destination,
@@ -2699,13 +2927,23 @@ message_t *message_create_defrag(message_t *fragment)
 {
 	private_message_t *this;
 
-	if (!fragment->get_payload(fragment, PLV1_FRAGMENT))
+	if (!fragment->get_payload(fragment, PLV1_FRAGMENT) &&
+		!fragment->get_payload(fragment, PLV2_FRAGMENT))
 	{
 		return NULL;
 	}
-	this = (private_message_t*)message_create(
-										fragment->get_major_version(fragment),
-										fragment->get_minor_version(fragment));
+	this = (private_message_t*)clone_message((private_message_t*)fragment);
+	/* we don't need a parser for IKEv2, the one for IKEv1 is created after
+	 * reassembling the original message */
+	this->parser->destroy(this->parser);
+	this->parser = NULL;
+	if (fragment->get_major_version(fragment) == IKEV1_MAJOR_VERSION)
+	{
+		/* we store the fragment ID in the message ID field, which should be
+		 * zero for fragments, but make sure */
+		this->message_id = 0;
+		this->public.add_fragment = _add_fragment_v1;
+	}
 	INIT(this->frag,
 		.max_packet = lib->settings->get_int(lib->settings,
 										"%s.max_packet", MAX_PACKET, lib->ns),
diff --git a/src/libcharon/encoding/message.h b/src/libcharon/encoding/message.h
index 69a8e93b1..a03aa8e96 100644
--- a/src/libcharon/encoding/message.h
+++ b/src/libcharon/encoding/message.h
@@ -268,8 +268,6 @@ struct message_t {
 	 * Generates the message split into fragments of the given size (total IP
 	 * datagram length).
 	 *
-	 * @note Only supported for IKEv1 at the moment.
-	 *
 	 * @param keymat	keymat to encrypt/sign message(s)
 	 * @param frag_len	fragment length (maximum total IP datagram length), 0
 	 *					for default value depending on address family
@@ -277,7 +275,6 @@ struct message_t {
 	 *					which are owned by the enumerator
 	 * @return
 	 *					- SUCCESS if message could be fragmented
-	 *					- INVALID_STATE if message is IKEv2
 	 *					- FAILED if fragmentation failed
 	 *					- and the possible return values of generate()
 	 */
@@ -303,8 +300,6 @@ struct message_t {
 	 * Once the message is completed it should be processed like any other
 	 * inbound message.
 	 *
-	 * @note Only supported for IKEv1 at the moment.
-	 *
 	 * @param fragment	fragment to add
 	 * @return
 	 *					- SUCCESS if message was reassembled