Implemented incremental processing of SWID tag [ID] inventory attribute

src/libimcv/plugins/imc_swid/imc_swid.c

@@ -17,8 +17,6 @@
 
 #include <imc/imc_agent.h>
 #include <imc/imc_msg.h>
-#include <ita/ita_attr.h>
-#include <ita/ita_attr_angel.h>
 #include "tcg/swid/tcg_swid_attr_req.h"
 #include "tcg/swid/tcg_swid_attr_tag_inv.h"
 #include "tcg/swid/tcg_swid_attr_tag_id_inv.h"
@@ -133,13 +131,12 @@ static bool add_swid_inventory(imc_state_t *state, imc_msg_t *msg,
 							   uint32_t request_id, bool full_tags,
 							   swid_inventory_t *targets)
 {
-	pa_tnc_attr_t *attr, *attr_angel, *attr_error;
+	pa_tnc_attr_t *attr, *attr_error;
 	imc_swid_state_t *swid_state;
 	swid_inventory_t *swid_inventory;
 	char *swid_directory, *swid_generator;
 	uint32_t eid_epoch;
-	size_t max_attr_size, attr_size, entry_size;
+	bool swid_pretty, swid_full;
-	bool first = TRUE, swid_pretty, swid_full;
 	enumerator_t *enumerator;
 
 	swid_directory = lib->settings->get_str(lib->settings,
@@ -172,63 +169,19 @@ static bool add_swid_inventory(imc_state_t *state, imc_msg_t *msg,
 	swid_state = (imc_swid_state_t*)state;
 	eid_epoch = swid_state->get_eid_epoch(swid_state);
 
-	/**
-	 * Compute the maximum TCG SWID Tag [ID] Inventory attribute size
-	 * leaving space for an additional ITA Angel attribute
-	 */
-	max_attr_size = state->get_max_msg_len(state) -
-					PA_TNC_HEADER_SIZE - PA_TNC_ATTR_HEADER_SIZE;
-
 	if (full_tags)
 	{
 		tcg_swid_attr_tag_inv_t *swid_attr;
 		swid_tag_t *tag;
-		chunk_t encoding, instance_id;
 
-		/* At least one TCG Tag Inventory attribute is sent */
+		/* Send a TCG SWID Tag Inventory attribute */
-		attr_size = PA_TNC_ATTR_HEADER_SIZE + TCG_SWID_TAG_INV_MIN_SIZE;
 		attr = tcg_swid_attr_tag_inv_create(request_id, eid_epoch, 1);
+		swid_attr = (tcg_swid_attr_tag_inv_t*)attr;
 
 		enumerator = swid_inventory->create_enumerator(swid_inventory);
 		while (enumerator->enumerate(enumerator, &tag))
 		{
-			instance_id = tag->get_instance_id(tag);
-			encoding = tag->get_encoding(tag);
-			entry_size = 2 + instance_id.len + 4 + encoding.len;
-
-			/* Check for oversize tags that cannot be transported */
-			if (PA_TNC_ATTR_HEADER_SIZE + TCG_SWID_TAG_INV_MIN_SIZE +
-				entry_size > max_attr_size)
-			{
-				attr_error = swid_error_create(TCG_SWID_RESPONSE_TOO_LARGE,
-											   request_id, max_attr_size,
-											   "oversize SWID tag omitted");
-				msg->add_attribute(msg, attr_error);
-				continue;
-			}
-
-			if (attr_size + entry_size > max_attr_size)
-			{
-				if (first)
-				{
-					/**
-					 * Send an ITA Start Angel attribute to the IMV signalling
-					 * that multiple TGC SWID Tag Inventory attributes follow
-					 */
-					attr_angel = ita_attr_angel_create(TRUE);
-					msg->add_attribute(msg, attr_angel);
-					first = FALSE;
-				}
-				msg->add_attribute(msg, attr);
-
-				/* create the next TCG SWID Tag Inventory attribute */
-				attr_size = PA_TNC_ATTR_HEADER_SIZE +
-							TCG_SWID_TAG_INV_MIN_SIZE;
-				attr = tcg_swid_attr_tag_inv_create(request_id, eid_epoch, 1);
-			}
-			swid_attr = (tcg_swid_attr_tag_inv_t*)attr;
 			swid_attr->add(swid_attr, tag->get_ref(tag));
-			attr_size += entry_size;
 		}
 		enumerator->destroy(enumerator);
 	}
@@ -237,7 +190,7 @@ static bool add_swid_inventory(imc_state_t *state, imc_msg_t *msg,
 		tcg_swid_attr_tag_id_inv_t *swid_id_attr;
 		swid_tag_id_t *tag_id;
 
-		/* Send a TCG Tag ID Inventory attribute */
+		/* Send a TCG SWID Tag ID Inventory attribute */
 		attr = tcg_swid_attr_tag_id_inv_create(request_id, eid_epoch, 1);
 		swid_id_attr = (tcg_swid_attr_tag_id_inv_t*)attr;
 
@@ -248,19 +201,10 @@ static bool add_swid_inventory(imc_state_t *state, imc_msg_t *msg,
 		}
 		enumerator->destroy(enumerator);
 	}
+
 	msg->add_attribute(msg, attr);
 	swid_inventory->destroy(swid_inventory);
 
-	if (!first)
-	{
-		/**
-		 * If we sent an ITA Start Angel attribute in the first place,
-		 * terminate by appending a matching ITA Stop Angel attribute.
-		 */
-		attr_angel = ita_attr_angel_create(FALSE);
-		msg->add_attribute(msg, attr_angel);
-	}
-
 	return TRUE;
 }
 

src/libimcv/plugins/imv_swid/imv_swid_agent.c

@@ -24,8 +24,6 @@
 #include <imv/imv_agent.h>
 #include <imv/imv_msg.h>
 #include <ietf/ietf_attr_pa_tnc_error.h>
-#include <ita/ita_attr.h>
-#include <ita/ita_attr_angel.h>
 #include "tcg/seg/tcg_seg_attr_max_size.h"
 #include "tcg/seg/tcg_seg_attr_seg_env.h"
 #include "tcg/swid/tcg_swid_attr_req.h"
@@ -185,20 +183,6 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 				reader->destroy(reader);
 			}
 		}
-		else if (type.vendor_id == PEN_ITA)
-		{
-			switch (type.type)
-			{
-				case ITA_ATTR_START_ANGEL:
-					swid_state->set_angel_count(swid_state, TRUE);
-					continue;
-				case ITA_ATTR_STOP_ANGEL:
-					swid_state->set_angel_count(swid_state, FALSE);
-					continue;
-				default:
-					continue;
-			}
-		}
 		else if (type.vendor_id != PEN_TCG)
 		{
 			continue;
@@ -209,6 +193,7 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 			case TCG_SWID_TAG_ID_INVENTORY:
 			{
 				tcg_swid_attr_tag_id_inv_t *attr_cast;
+				uint32_t missing;
 				int tag_id_count;
 
 				state->set_action_flags(state, IMV_SWID_ATTR_TAG_ID_INV);
@@ -218,11 +203,14 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 				last_eid = attr_cast->get_last_eid(attr_cast, &eid_epoch);
 				inventory = attr_cast->get_inventory(attr_cast);
 				tag_id_count = inventory->get_count(inventory);
+				missing = attr_cast->get_tag_id_count(attr_cast);
+				swid_state->set_missing(swid_state, missing);
 
 				DBG2(DBG_IMV, "received SWID tag ID inventory with %d item%s "
-							  "for request %d at eid %d of epoch 0x%08x",
+					 "for request %d at eid %d of epoch 0x%08x, %d item%s to "
-							   tag_id_count, (tag_id_count == 1) ? "" : "s",
+					 "follow", tag_id_count, (tag_id_count == 1) ? "" : "s",
-							   request_id, last_eid, eid_epoch);
+					 request_id, last_eid, eid_epoch, missing,
+					 (missing == 1) ? "" : "s");
 
 				if (request_id == swid_state->get_request_id(swid_state))
 				{
@@ -234,6 +222,7 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 					DBG1(DBG_IMV, "no workitem found for SWID tag ID inventory "
 								  "with request ID %d", request_id);
 				}
+				attr_cast->clear_inventory(attr_cast);
 				break;
 			 }
 			case TCG_SWID_TAG_INVENTORY:
@@ -243,6 +232,7 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 				chunk_t tag_encoding;
 				json_object *jobj, *jarray, *jstring;
 				char *tag_str;
+				uint32_t missing;
 				int tag_count;
 				enumerator_t *e;
 
@@ -253,12 +243,13 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 				last_eid = attr_cast->get_last_eid(attr_cast, &eid_epoch);
 				inventory = attr_cast->get_inventory(attr_cast);
 				tag_count = inventory->get_count(inventory);
+				missing = attr_cast->get_tag_count(attr_cast);
+				swid_state->set_missing(swid_state, missing);
 
 				DBG2(DBG_IMV, "received SWID tag inventory with %d item%s for "
-							  "request %d at eid %d of epoch 0x%08x",
+					 "request %d at eid %d of epoch 0x%08x, %d item%s to follow",
-							   tag_count, (tag_count == 1) ? "" : "s",
+					 tag_count, (tag_count == 1) ? "" : "s", request_id,
-							   request_id, last_eid, eid_epoch);
+					 last_eid, eid_epoch, missing, (missing == 1) ? "" : "s");
-
 
 				if (request_id == swid_state->get_request_id(swid_state))
 				{
@@ -295,9 +286,11 @@ static TNC_Result receive_msg(private_imv_swid_agent_t *this,
 					DBG1(DBG_IMV, "no workitem found for SWID tag inventory "
 								  "with request ID %d", request_id);
 				}
+				attr_cast->clear_inventory(attr_cast);
+				break;
 			}
 			default:
-				continue;
+				break;
 		 }
 	}
 	enumerator->destroy(enumerator);
@@ -498,7 +491,7 @@ METHOD(imv_agent_if_t, batch_ending, TNC_Result,
 
 	if (handshake_state == IMV_SWID_STATE_WORKITEMS &&
 	   (received & (IMV_SWID_ATTR_TAG_INV|IMV_SWID_ATTR_TAG_ID_INV)) &&
-		swid_state->get_angel_count(swid_state) <= 0)
+		swid_state->get_missing(swid_state) == 0)
 	{
 		TNC_IMV_Evaluation_Result eval;
 		TNC_IMV_Action_Recommendation rec;

src/libimcv/plugins/imv_swid/imv_swid_state.c

@@ -117,6 +117,11 @@ struct private_imv_swid_state_t {
 	 */
 	int tag_count;
 
+	/**
+	 * Number of missing SWID Tags or Tag IDs
+	 */
+	uint32_t missing;
+
 	/**
 	 * Top level JSON object
 	 */
@@ -127,11 +132,6 @@ struct private_imv_swid_state_t {
 	 */
 	json_object *jarray;
 
-	/**
-	 * Angel count
-	 */
-	int angel_count;
-
 };
 
 METHOD(imv_state_t, get_connection_id, TNC_ConnectionID,
@@ -313,6 +313,18 @@ METHOD(imv_swid_state_t, get_swid_inventory, json_object*,
 	return this->jobj;
 }
 
+METHOD(imv_swid_state_t, set_missing, void,
+	private_imv_swid_state_t *this, uint32_t count)
+{
+	this->missing = count;
+}
+
+METHOD(imv_swid_state_t, get_missing, uint32_t,
+	private_imv_swid_state_t *this)
+{
+	return this->missing;
+}
+
 METHOD(imv_swid_state_t, set_count, void,
 	private_imv_swid_state_t *this, int tag_id_count, int tag_count)
 {
@@ -333,18 +345,6 @@ METHOD(imv_swid_state_t, get_count, void,
 	}
 }
 
-METHOD(imv_swid_state_t, set_angel_count, void,
-	private_imv_swid_state_t *this, bool start)
-{
-	this->angel_count += start ? 1 : -1;
-}
-
-METHOD(imv_swid_state_t, get_angel_count, int,
-	private_imv_swid_state_t *this)
-{
-	return this->angel_count;
-}
-
 /**
  * Described in header.
  */
@@ -380,10 +380,10 @@ imv_state_t *imv_swid_state_create(TNC_ConnectionID connection_id)
 			.get_request_id = _get_request_id,
 			.set_swid_inventory = _set_swid_inventory,
 			.get_swid_inventory = _get_swid_inventory,
+			.set_missing = _set_missing,
+			.get_missing = _get_missing,
 			.set_count = _set_count,
 			.get_count = _get_count,
-			.set_angel_count = _set_angel_count,
-			.get_angel_count = _get_angel_count,
 		},
 		.state = TNC_CONNECTION_STATE_CREATE,
 		.rec = TNC_IMV_ACTION_RECOMMENDATION_NO_RECOMMENDATION,

src/libimcv/plugins/imv_swid/imv_swid_state.h

@@ -95,6 +95,20 @@ struct imv_swid_state_t {
      */
     json_object* (*get_swid_inventory)(imv_swid_state_t *this);
 
+	/**
+	 * Set the number of still missing SWID Tags or Tag IDs
+	 *
+	 * @param count				Number of missing SWID Tags or Tag IDs
+	 */
+	void (*set_missing)(imv_swid_state_t *this, uint32_t count);
+
+	/**
+	 * Get the number of still missing SWID Tags or Tag IDs
+	 *
+	 * @result					Number of missing SWID Tags or Tag IDs
+	 */
+	uint32_t (*get_missing)(imv_swid_state_t *this);
+
 	/**
 	 * Set [or with multiple attributes increment] SWID Tag [ID] counters
 	 *
@@ -110,21 +124,6 @@ struct imv_swid_state_t {
 	 * @param tag_count			Number of received SWID Tags
 	 */
 	void (*get_count)(imv_swid_state_t *this, int *tag_id_count, int *tag_count);
-
-	/**
-	 * Increase/Decrease the ITA Angel count
-	 *
-	 * @param start				TRUE increases and FALSE decreases count by one
-	 */
-	void (*set_angel_count)(imv_swid_state_t *this, bool start);
-
-	/**
-	 * Get the ITA Angel count
-	 *
-	 * @return					ITA Angel count
-	 */
-	int (*get_angel_count)(imv_swid_state_t *this);
-
 };
 
 /**

src/libimcv/tcg/swid/tcg_swid_attr_tag_id_inv.c

@@ -69,10 +69,20 @@ struct private_tcg_swid_attr_tag_id_inv_t {
 	size_t length;
 
 	/**
-	 * Attribute value or segment
+	 * Offset up to which attribute value has been processed
+	 */
+	size_t offset;
+
+	/**
+	 * Current position of attribute value pointer
 	 */
 	chunk_t value;
 
+	/**
+	 * Contains complete attribute or current segment
+	 */
+	chunk_t segment;
+
 	/**
 	 * Noskip flag
 	 */
@@ -93,6 +103,11 @@ struct private_tcg_swid_attr_tag_id_inv_t {
 	 */
 	uint32_t last_eid;
 
+	/**
+	 * Number of SWID Tag IDs in attribute
+	 */
+	uint32_t tag_id_count;
+
 	/**
 	 * SWID Tag ID Inventory
 	 */
@@ -160,6 +175,7 @@ METHOD(pa_tnc_attr_t, build, void,
 	enumerator->destroy(enumerator);
 
 	this->value = writer->extract_buf(writer);
+	this->segment = this->value;
 	this->length = this->value.len;
 	writer->destroy(writer);
 }
@@ -168,66 +184,74 @@ METHOD(pa_tnc_attr_t, process, status_t,
 	private_tcg_swid_attr_tag_id_inv_t *this, uint32_t *offset)
 {
 	bio_reader_t *reader;
-	uint32_t tag_id_count;
 	uint8_t reserved;
 	chunk_t tag_creator, unique_sw_id, instance_id;
 	swid_tag_id_t *tag_id;
+	status_t status = NEED_MORE;
 
-	*offset = 0;
+	if (this->offset == 0)
-
-	if (this->value.len < this->length)
 	{
-		return NEED_MORE;
+		if (this->length < TCG_SWID_TAG_ID_INV_MIN_SIZE)
-	}
+		{
-	if (this->value.len < TCG_SWID_TAG_ID_INV_MIN_SIZE)
+			DBG1(DBG_TNC, "insufficient data for %N/%N", pen_names, PEN_TCG,
-	{
+						   tcg_attr_names, this->type.type);
-		DBG1(DBG_TNC, "insufficient data for SWID Tag Identifier Inventory");
+			*offset = this->offset;
-		return FAILED;
+			return FAILED;
+		}
+		if (this->value.len < TCG_SWID_TAG_ID_INV_MIN_SIZE)
+		{
+			return NEED_MORE;
+		}
+		reader = bio_reader_create(this->value);
+		reader->read_uint8 (reader, &reserved);
+		reader->read_uint24(reader, &this->tag_id_count);
+		reader->read_uint32(reader, &this->request_id);
+		reader->read_uint32(reader, &this->eid_epoch);
+		reader->read_uint32(reader, &this->last_eid);
+		this->offset = TCG_SWID_TAG_ID_INV_MIN_SIZE;
+		this->value = reader->peek(reader);
+		reader->destroy(reader);
 	}
 
 	reader = bio_reader_create(this->value);
-	reader->read_uint8 (reader, &reserved);
-	reader->read_uint24(reader, &tag_id_count);
-	reader->read_uint32(reader, &this->request_id);
-	reader->read_uint32(reader, &this->eid_epoch);
-	reader->read_uint32(reader, &this->last_eid);
-	*offset = TCG_SWID_TAG_ID_INV_MIN_SIZE;
 
-	while (tag_id_count--)
+	while (this->tag_id_count)
 	{
-		if (!reader->read_data16(reader, &tag_creator))
+		if (!reader->read_data16(reader, &tag_creator)  ||
+			!reader->read_data16(reader, &unique_sw_id) ||
+			!reader->read_data16(reader, &instance_id))
 		{
-			DBG1(DBG_TNC, "insufficient data for Tag Creator field");
+			goto end;
-			return FAILED;
 		}
-		*offset += 2 + tag_creator.len;
-
-		if (!reader->read_data16(reader, &unique_sw_id))
-		{
-			DBG1(DBG_TNC, "insufficient data for Unique Software ID");
-			return FAILED;
-		}
-		*offset += 2 + unique_sw_id.len;
-		
-		if (!reader->read_data16(reader, &instance_id))
-		{
-			DBG1(DBG_TNC, "insufficient data for Instance ID");
-			return FAILED;
-		}
-		*offset += 2 + instance_id.len;
-
 		tag_id = swid_tag_id_create(tag_creator, unique_sw_id, instance_id);
 		this->inventory->add(this->inventory, tag_id);
-	}
+		this->offset += this->value.len - reader->remaining(reader);
-	reader->destroy(reader);
+		this->value = reader->peek(reader);
 
-	return SUCCESS;
+		/* at least one tag ID was processed */
+		status = SUCCESS;
+		this->tag_id_count--;
+	}
+
+	if (this->length != this->offset)
+	{
+		DBG1(DBG_TNC, "inconsistent length for %N/%N", pen_names, PEN_TCG,
+					   tcg_attr_names, this->type.type);
+		*offset = this->offset;
+		status = FAILED;
+	}
+
+end:
+	reader->destroy(reader);
+	return status;
 }
 
 METHOD(pa_tnc_attr_t, add_segment, void,
 	private_tcg_swid_attr_tag_id_inv_t *this, chunk_t segment)
 {
-	this->value = chunk_cat("mc", this->value, segment);
+	this->value = chunk_cat("cc", this->value, segment);
+	chunk_free(&this->segment);
+	this->segment = this->value;
 }
 
 METHOD(pa_tnc_attr_t, get_ref, pa_tnc_attr_t*,
@@ -243,7 +267,7 @@ METHOD(pa_tnc_attr_t, destroy, void,
 	if (ref_put(&this->ref))
 	{
 		this->inventory->destroy(this->inventory);
-		free(this->value.ptr);
+		free(this->segment.ptr);
 		free(this);
 	}
 }
@@ -270,12 +294,25 @@ METHOD(tcg_swid_attr_tag_id_inv_t, get_last_eid, uint32_t,
 	return this->last_eid;
 }
 
+METHOD(tcg_swid_attr_tag_id_inv_t, get_tag_id_count, uint32_t,
+	private_tcg_swid_attr_tag_id_inv_t *this)
+{
+	return this->tag_id_count;
+}
+
 METHOD(tcg_swid_attr_tag_id_inv_t, get_inventory, swid_inventory_t*,
 	private_tcg_swid_attr_tag_id_inv_t *this)
 {
 	return this->inventory;
 }
 
+METHOD(tcg_swid_attr_tag_id_inv_t, clear_inventory, void,
+	private_tcg_swid_attr_tag_id_inv_t *this)
+{
+	this->inventory->destroy(this->inventory);
+	this->inventory = swid_inventory_create(FALSE);
+}
+
 /**
  * Described in header.
  */
@@ -301,7 +338,9 @@ pa_tnc_attr_t *tcg_swid_attr_tag_id_inv_create(uint32_t request_id,
 			.add = _add,
 			.get_request_id = _get_request_id,
 			.get_last_eid = _get_last_eid,
+			.get_tag_id_count = _get_tag_id_count,
 			.get_inventory = _get_inventory,
+			.clear_inventory = _clear_inventory,
 		},
 		.type = { PEN_TCG, TCG_SWID_TAG_ID_INVENTORY },
 		.request_id = request_id,
@@ -339,14 +378,19 @@ pa_tnc_attr_t *tcg_swid_attr_tag_id_inv_create_from_data(size_t length,
 			.add = _add,
 			.get_request_id = _get_request_id,
 			.get_last_eid = _get_last_eid,
+			.get_tag_id_count = _get_tag_id_count,
 			.get_inventory = _get_inventory,
+			.clear_inventory = _clear_inventory,
 		},
 		.type = { PEN_TCG, TCG_SWID_TAG_ID_INVENTORY },
 		.length = length,
-		.value = chunk_clone(data),
+		.segment = chunk_clone(data),
 		.inventory = swid_inventory_create(FALSE),
 		.ref = 1,
 	);
 
+	/* received either complete attribute value or first segment */
+	this->value = this->segment;
+
 	return &this->public.pa_tnc_attribute;
 }

src/libimcv/tcg/swid/tcg_swid_attr_tag_id_inv.h

@@ -65,6 +65,13 @@ struct tcg_swid_attr_tag_id_inv_t {
 	uint32_t (*get_last_eid)(tcg_swid_attr_tag_id_inv_t *this,
 							 uint32_t *eid_epoch);
 
+	/**
+	 * Get count of remaining SWID tag IDs
+	 *
+	 * @return					SWID Tag ID count
+	 */
+	uint32_t (*get_tag_id_count)(tcg_swid_attr_tag_id_inv_t *this);
+
 	/**
 	 * Get Inventory of SWID tag IDs
 	 *
@@ -72,6 +79,11 @@ struct tcg_swid_attr_tag_id_inv_t {
 	 */
 	swid_inventory_t* (*get_inventory)(tcg_swid_attr_tag_id_inv_t *this);
 
+	/**
+	 * Remove all SWID Tag IDs from the Inventory
+	 */
+	void (*clear_inventory)(tcg_swid_attr_tag_id_inv_t *this);
+
 };
 
 /**

src/libimcv/tcg/swid/tcg_swid_attr_tag_inv.c

@@ -69,10 +69,20 @@ struct private_tcg_swid_attr_tag_inv_t {
 	size_t length;
 
 	/**
-	 * Attribute value or segment
+	 * Offset up to which attribute value has been processed
+	 */
+	size_t offset;
+
+	/**
+	 * Current position of attribute value pointer
 	 */
 	chunk_t value;
 
+	/**
+	 * Contains complete attribute or current segment
+	 */
+	chunk_t segment;
+
 	/**
 	 * Noskip flag
 	 */
@@ -93,6 +103,11 @@ struct private_tcg_swid_attr_tag_inv_t {
 	 */
 	uint32_t last_eid;
 
+	/**
+	 * Number of SWID Tags in attribute
+	 */
+	uint32_t tag_count;
+
 	/**
 	 * SWID Tag Inventory
 	 */
@@ -156,6 +171,7 @@ METHOD(pa_tnc_attr_t, build, void,
 	enumerator->destroy(enumerator);
 
 	this->value = writer->extract_buf(writer);
+	this->segment = this->value;
 	this->length = this->value.len;
 	writer->destroy(writer);
 }
@@ -164,59 +180,73 @@ METHOD(pa_tnc_attr_t, process, status_t,
 	private_tcg_swid_attr_tag_inv_t *this, uint32_t *offset)
 {
 	bio_reader_t *reader;
-	uint32_t tag_count;
 	uint8_t reserved;
 	chunk_t tag_encoding, instance_id;
 	swid_tag_t *tag;
+	status_t status = NEED_MORE;
 
-	*offset = 0;
+	if (this->offset == 0)
-
-	if (this->value.len < this->length)
 	{
-		return NEED_MORE;
+		if (this->length < TCG_SWID_TAG_INV_MIN_SIZE)
-	}
+		{
-	if (this->value.len < TCG_SWID_TAG_INV_MIN_SIZE)
+			DBG1(DBG_TNC, "insufficient data for %N", tcg_attr_names,
-	{
+													  this->type.type);
-		DBG1(DBG_TNC, "insufficient data for SWID Tag Inventory");
+			*offset = this->offset;
-		return FAILED;
+			return FAILED;
+		}
+		if (this->value.len < TCG_SWID_TAG_INV_MIN_SIZE)
+		{
+			return NEED_MORE;
+		}
+		reader = bio_reader_create(this->value);
+		reader->read_uint8 (reader, &reserved);
+		reader->read_uint24(reader, &this->tag_count);
+		reader->read_uint32(reader, &this->request_id);
+		reader->read_uint32(reader, &this->eid_epoch);
+		reader->read_uint32(reader, &this->last_eid);
+		this->offset = TCG_SWID_TAG_INV_MIN_SIZE;
+		this->value = reader->peek(reader);
+		reader->destroy(reader);
 	}
 
 	reader = bio_reader_create(this->value);
-	reader->read_uint8 (reader, &reserved);
-	reader->read_uint24(reader, &tag_count);
-	reader->read_uint32(reader, &this->request_id);
-	reader->read_uint32(reader, &this->eid_epoch);
-	reader->read_uint32(reader, &this->last_eid);
-	*offset = TCG_SWID_TAG_INV_MIN_SIZE;
 
-	while (tag_count--)
+	while (this->tag_count)
 	{
-		if (!reader->read_data16(reader, &instance_id))
+		if (!reader->read_data16(reader, &instance_id) ||
+			!reader->read_data32(reader, &tag_encoding))
 		{
-			DBG1(DBG_TNC, "insufficient data for Instance ID");
+			goto end;
-			return FAILED;
 		}
-		*offset += 2 + instance_id.len;
-
-		if (!reader->read_data32(reader, &tag_encoding))
-		{
-			DBG1(DBG_TNC, "insufficient data for Tag");
-			return FAILED;
-		}
-		*offset += 4 + tag_encoding.len;
-
 		tag = swid_tag_create(tag_encoding, instance_id);
 		this->inventory->add(this->inventory, tag);
-	}
+		this->offset += this->value.len - reader->remaining(reader);
-	reader->destroy(reader);
+		this->value = reader->peek(reader);
 
-	return SUCCESS;
+		/* at least one tag was processed */
+		status = SUCCESS;
+		this->tag_count--;
+	}
+
+	if (this->length != this->offset)
+	{
+		DBG1(DBG_TNC, "inconsistent length for %N", tcg_attr_names,
+													this->type.type);
+		*offset = this->offset;
+		status = FAILED;
+	}
+
+end:
+	reader->destroy(reader);
+	return status;
 }
 
 METHOD(pa_tnc_attr_t, add_segment, void,
 	private_tcg_swid_attr_tag_inv_t *this, chunk_t segment)
 {
-	this->value = chunk_cat("mc", this->value, segment);
+	this->value = chunk_cat("cc", this->value, segment);
+	chunk_free(&this->segment);
+	this->segment = this->value;
 }
 
 METHOD(pa_tnc_attr_t, get_ref, pa_tnc_attr_t*,
@@ -232,7 +262,7 @@ METHOD(pa_tnc_attr_t, destroy, void,
 	if (ref_put(&this->ref))
 	{
 		this->inventory->destroy(this->inventory);
-		free(this->value.ptr);
+		free(this->segment.ptr);
 		free(this);
 	}
 }
@@ -259,12 +289,25 @@ METHOD(tcg_swid_attr_tag_inv_t, get_last_eid, uint32_t,
 	return this->last_eid;
 }
 
+METHOD(tcg_swid_attr_tag_inv_t, get_tag_count, uint32_t,
+	private_tcg_swid_attr_tag_inv_t *this)
+{
+	return this->tag_count;
+}
+
 METHOD(tcg_swid_attr_tag_inv_t, get_inventory, swid_inventory_t*,
 	private_tcg_swid_attr_tag_inv_t *this)
 {
 	return this->inventory;
 }
 
+METHOD(tcg_swid_attr_tag_inv_t, clear_inventory, void,
+	private_tcg_swid_attr_tag_inv_t *this)
+{
+	this->inventory->destroy(this->inventory);
+	this->inventory = swid_inventory_create(TRUE);
+}
+
 /**
  * Described in header.
  */
@@ -289,7 +332,9 @@ pa_tnc_attr_t *tcg_swid_attr_tag_inv_create(uint32_t request_id,
 			.add = _add,
 			.get_request_id = _get_request_id,
 			.get_last_eid = _get_last_eid,
+			.get_tag_count = _get_tag_count,
 			.get_inventory = _get_inventory,
+			.clear_inventory = _clear_inventory,
 		},
 		.type = { PEN_TCG, TCG_SWID_TAG_INVENTORY },
 		.request_id = request_id,
@@ -326,14 +371,19 @@ pa_tnc_attr_t *tcg_swid_attr_tag_inv_create_from_data(size_t length,
 			.add = _add,
 			.get_request_id = _get_request_id,
 			.get_last_eid = _get_last_eid,
+			.get_tag_count = _get_tag_count,
 			.get_inventory = _get_inventory,
+			.clear_inventory = _clear_inventory,
 		},
 		.type = { PEN_TCG, TCG_SWID_TAG_INVENTORY },
 		.length = length,
-		.value = chunk_clone(data),
+		.segment = chunk_clone(data),
 		.inventory = swid_inventory_create(TRUE),
 		.ref = 1,
 	);
 
+	/* received either complete attribute value or first segment */
+	this->value = this->segment;
+
 	return &this->public.pa_tnc_attribute;
 }

src/libimcv/tcg/swid/tcg_swid_attr_tag_inv.h

@@ -64,6 +64,13 @@ struct tcg_swid_attr_tag_inv_t {
 	uint32_t (*get_last_eid)(tcg_swid_attr_tag_inv_t *this,
 							  uint32_t *eid_epoch);
 
+	/**
+	 * Get count of remaining SWID tags
+	 *
+	 * @return					SWID Tag count
+	 */
+	uint32_t (*get_tag_count)(tcg_swid_attr_tag_inv_t *this);
+
 	/**
 	 * Get Inventory of SWID tags
 	 *
@@ -71,6 +78,11 @@ struct tcg_swid_attr_tag_inv_t {
 	 */
 	swid_inventory_t* (*get_inventory)(tcg_swid_attr_tag_inv_t *this);
 
+	/**
+	 * Remove all SWID Tags from the Inventory
+	 */
+	void (*clear_inventory)(tcg_swid_attr_tag_inv_t *this);
+
 };
 
 /**