Implemented IF-M segmentation

6 files changed, 1086 insertions, 0 deletions

diff --git a/src/libimcv/seg/seg_contract.c b/src/libimcv/seg/seg_contract.c
new file mode 100644
index 000000000..589d6d1cd
--- /dev/null
+++ b/src/libimcv/seg/seg_contract.c
@@ -0,0 +1,413 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "seg_contract.h"
+#include "seg_env.h"
+
+#include <utils/debug.h>
+#include <bio/bio_writer.h>
+
+#include <tncif_pa_subtypes.h>
+
+#include <tcg/seg/tcg_seg_attr_seg_env.h>
+
+typedef struct private_seg_contract_t private_seg_contract_t;
+
+/**
+ * Private data of a seg_contract_t object.
+ */
+struct private_seg_contract_t {
+
+	/**
+	 * Public seg_contract_t interface.
+	 */
+	seg_contract_t public;
+
+	/**
+	 * PA-TNC message type
+	 */
+	pen_type_t msg_type;
+
+	/**
+	 * Maximum PA-TNC attribute size
+	 */
+	uint32_t max_attr_size;
+
+	/**
+	 * Maximum PA-TNC attribute segment size
+	 */
+	uint32_t max_seg_size;
+
+	/**
+	 * Maximum PA-TNC attribute segment size
+	 */
+	uint32_t last_base_attr_id;
+
+	/**
+	 * List of attribute segment envelopes
+	 */
+
+	linked_list_t *seg_envs;
+
+	/**
+	 * Is this a null contract?
+	 */
+	bool is_null;
+
+	/**
+	 * Contract role
+	 */
+	bool is_issuer;
+
+	/**
+	 * Issuer ID (either IMV ID or IMC ID)
+	 */
+	TNC_UInt32 issuer_id;
+
+	/**
+	 * IMC/IMV role
+	 */
+	bool is_imc;
+
+};
+
+METHOD(seg_contract_t, get_msg_type, pen_type_t,
+	private_seg_contract_t *this)
+{
+	return this->msg_type;
+}
+
+METHOD(seg_contract_t, set_max_size, void,
+	private_seg_contract_t *this, uint32_t max_attr_size, uint32_t max_seg_size)
+{
+	this->max_attr_size = max_attr_size;
+	this->max_seg_size = max_seg_size;
+	this->is_null = max_attr_size == SEG_CONTRACT_MAX_SIZE_VALUE &&
+					max_seg_size  == SEG_CONTRACT_MAX_SIZE_VALUE;
+}
+
+METHOD(seg_contract_t, get_max_size, void,
+	private_seg_contract_t *this, uint32_t *max_attr_size, uint32_t *max_seg_size)
+{
+	if (max_attr_size)
+	{
+		*max_attr_size = this->max_attr_size;
+	}
+	if (max_seg_size)
+	{
+		*max_seg_size = this->max_seg_size;
+	}
+}
+
+METHOD(seg_contract_t, check_size, bool,
+	private_seg_contract_t *this, pa_tnc_attr_t *attr, bool *oversize)
+{
+	chunk_t attr_value;
+	size_t attr_len;
+
+	*oversize = FALSE;
+
+	if (this->is_null)
+	{
+		/* null segmentation contract */
+		return FALSE;
+	}
+	attr->build(attr);
+	attr_value = attr->get_value(attr);
+	attr_len = PA_TNC_ATTR_HEADER_SIZE + attr_value.len;
+
+	if (attr_len > this->max_attr_size)
+	{
+		/* oversize attribute */
+		*oversize = TRUE;
+		return FALSE;
+	}
+	if (this->max_seg_size == SEG_CONTRACT_NO_FRAGMENTATION)
+	{
+		/* no fragmentation wanted */
+		return FALSE;
+	}
+	return attr_value.len > this->max_seg_size + TCG_SEG_ATTR_SEG_ENV_HEADER;
+}
+
+METHOD(seg_contract_t, first_segment, pa_tnc_attr_t*,
+	private_seg_contract_t *this, pa_tnc_attr_t *attr)
+{
+	seg_env_t *seg_env;
+
+	seg_env = seg_env_create(++this->last_base_attr_id, attr,
+							 this->max_seg_size);
+	if (!seg_env)
+	{
+		return NULL;
+	}
+	this->seg_envs->insert_last(this->seg_envs, seg_env);
+
+	return seg_env->first_segment(seg_env);
+}
+
+METHOD(seg_contract_t, next_segment, pa_tnc_attr_t*,
+	private_seg_contract_t *this, uint32_t base_attr_id)
+{
+	pa_tnc_attr_t *seg_env_attr = NULL;
+	seg_env_t *seg_env;
+	bool last_segment = FALSE;
+	enumerator_t *enumerator;
+
+	enumerator = this->seg_envs->create_enumerator(this->seg_envs);
+	while (enumerator->enumerate(enumerator, &seg_env))
+	{
+		if (seg_env->get_base_attr_id(seg_env) == base_attr_id)
+		{
+			seg_env_attr = seg_env->next_segment(seg_env, &last_segment);
+			if (!seg_env_attr)
+			{
+				break;
+			}
+			if (last_segment)
+			{
+				this->seg_envs->remove_at(this->seg_envs, enumerator);
+				seg_env->destroy(seg_env);
+			}
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	return seg_env_attr;
+}
+
+METHOD(seg_contract_t, add_segment, pa_tnc_attr_t*,
+	private_seg_contract_t *this, pa_tnc_attr_t *attr, pa_tnc_attr_t **error,
+	bool *more)
+{
+	tcg_seg_attr_seg_env_t *seg_env_attr;
+	seg_env_t *current, *seg_env = NULL;
+	pa_tnc_attr_t *base_attr;
+	uint32_t base_attr_id;
+	uint8_t flags;
+	chunk_t segment_data;
+	enumerator_t *enumerator;
+
+	seg_env_attr = (tcg_seg_attr_seg_env_t*)attr;
+	base_attr_id = seg_env_attr->get_base_attr_id(seg_env_attr);
+	segment_data = seg_env_attr->get_segment(seg_env_attr, &flags);
+	*more = flags & SEG_ENV_FLAG_MORE;
+	*error = NULL;
+
+	enumerator = this->seg_envs->create_enumerator(this->seg_envs);
+	while (enumerator->enumerate(enumerator, &current))
+	{
+		if (current->get_base_attr_id(current) == base_attr_id)
+		{
+			seg_env = current;
+			if (!(*more))
+			{
+				this->seg_envs->remove_at(this->seg_envs, enumerator);
+			}
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	if (flags & SEG_ENV_FLAG_START)
+	{
+		if (seg_env)
+		{
+			DBG1(DBG_TNC, "base attribute ID %d is already in use",
+						   base_attr_id);
+			return NULL;
+		}
+		DBG2(DBG_TNC, "received first segment for base attribute ID %d "
+					  "(%d bytes)", base_attr_id, segment_data.len);
+		seg_env = seg_env_create_from_data(base_attr_id, segment_data,
+										   this->max_seg_size);
+		this->seg_envs->insert_last(this->seg_envs, seg_env);
+	}
+	else
+	{
+		if (!seg_env)
+		{
+			DBG1(DBG_TNC, "base attribute ID %d not found", base_attr_id);
+			return NULL;
+		}
+		DBG2(DBG_TNC, "received %s segment for base attribute ID %d "
+					  "(%d bytes)", (*more) ? "next" : "last", base_attr_id,
+					   segment_data.len);
+		seg_env->add_segment(seg_env, segment_data);
+	}
+	if (*more)
+	{
+		return NULL;
+	}
+	base_attr = seg_env->get_base_attr(seg_env, error);
+	seg_env->destroy(seg_env);
+
+	return base_attr;
+}
+
+
+METHOD(seg_contract_t, is_issuer, bool,
+	private_seg_contract_t *this)
+{
+	return this->is_issuer;
+}
+
+METHOD(seg_contract_t, is_null, bool,
+	private_seg_contract_t *this)
+{
+	return this->is_null;
+}
+
+METHOD(seg_contract_t, get_info_string, void,
+	private_seg_contract_t *this, char *buf, size_t len, bool request)
+{
+	enum_name_t *pa_subtype_names;
+	uint32_t msg_vid, msg_subtype;
+	char *pos = buf;
+	int written;
+
+	/* nul-terminate the string buffer */
+	buf[--len] = '\0';
+
+	if (this->is_issuer && request)
+	{
+		written = snprintf(pos, len, "%s %d requests",
+						  this->is_imc ? "IMC" : "IMV", this->issuer_id);
+	}
+	else
+	{
+		written = snprintf(pos, len, "received");
+	}
+	if (written < 0 || written > len)
+	{
+		return;
+	}
+	pos += written;
+	len -= written;
+
+	written = snprintf(pos, len, " a %ssegmentation contract%s ",
+					   this->is_null ? "null" : "", request ? "" : " response");
+	if (written < 0 || written > len)
+	{
+		return;
+	}
+	pos += written;
+	len -= written;
+
+	if (!this->is_issuer && this->issuer_id != TNC_IMVID_ANY)
+	{
+		written = snprintf(pos, len, "from %s %d ",
+						   this->is_imc ? "IMV" : "IMC", this->issuer_id);
+		if (written < 0 || written > len)
+		{
+			return;
+		}
+		pos += written;
+		len -= written;
+	}
+
+	msg_vid     = this->msg_type.vendor_id;
+	msg_subtype = this->msg_type.type;
+	pa_subtype_names = get_pa_subtype_names(msg_vid);
+	if (pa_subtype_names)
+	{
+		written = snprintf(pos, len, "for PA message type '%N/%N' "
+						   "0x%06x/0x%08x", pen_names, msg_vid,
+						   pa_subtype_names, msg_subtype, msg_vid,
+						   msg_subtype);
+	}
+	else
+	{
+		written = snprintf(pos, len, "for PA message type '%N' "
+						   "0x%06x/0x%08x", pen_names, msg_vid,
+						   msg_vid, msg_subtype);
+	}
+	if (written < 0 || written > len)
+	{
+		return;
+	}
+	pos += written;
+	len -= written;
+
+	if (!this->is_null)
+	{
+		written = snprintf(pos, len, "\n  maximum attribute size of %u bytes "
+						   "with ", this->max_attr_size);
+		if (written < 0 || written > len)
+		{
+			return;
+		}
+		pos += written;
+		len -= written;
+
+		if (this->max_seg_size == SEG_CONTRACT_MAX_SIZE_VALUE)
+		{
+			written = snprintf(pos, len, "no segmentation");
+		}
+		else
+		{
+			written = snprintf(pos, len, "maximum segment size of %u bytes",
+							   this->max_seg_size);
+		}
+	}
+}
+
+METHOD(seg_contract_t, destroy, void,
+	private_seg_contract_t *this)
+{
+	this->seg_envs->destroy_offset(this->seg_envs, offsetof(seg_env_t, destroy));
+	free(this);
+}
+
+/**
+ * See header
+ */
+seg_contract_t *seg_contract_create(pen_type_t msg_type,
+								    uint32_t max_attr_size,
+									uint32_t max_seg_size,
+									bool is_issuer, TNC_UInt32 issuer_id,
+									bool is_imc)
+{
+	private_seg_contract_t *this;
+
+	INIT(this,
+		.public = {
+			.get_msg_type = _get_msg_type,
+			.set_max_size = _set_max_size,
+			.get_max_size = _get_max_size,
+			.check_size = _check_size,
+			.first_segment = _first_segment,
+			.next_segment = _next_segment,
+			.add_segment = _add_segment,
+			.is_issuer = _is_issuer,
+			.is_null = _is_null,
+			.get_info_string = _get_info_string,
+			.destroy = _destroy,
+		},
+		.msg_type = msg_type,
+		.max_attr_size = max_attr_size,
+		.max_seg_size = max_seg_size,
+		.seg_envs = linked_list_create(),
+		.is_issuer = is_issuer,
+		.issuer_id = issuer_id,
+		.is_imc = is_imc,
+		.is_null = max_attr_size == SEG_CONTRACT_MAX_SIZE_VALUE &&
+				   max_seg_size  == SEG_CONTRACT_MAX_SIZE_VALUE,
+	);
+
+	return &this->public;
+}
+
diff --git a/src/libimcv/seg/seg_contract.h b/src/libimcv/seg/seg_contract.h
new file mode 100644
index 000000000..48828c472
--- /dev/null
+++ b/src/libimcv/seg/seg_contract.h
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup seg_contract seg_contract
+ * @{ @ingroup libimcv
+ */
+
+#ifndef SEG_CONTRACT_H_
+#define SEG_CONTRACT_H_
+
+typedef struct seg_contract_t seg_contract_t;
+
+#include "pa_tnc/pa_tnc_attr.h"
+
+#include <library.h>
+#include <pen/pen.h>
+
+#include <tncif.h>
+
+#define SEG_CONTRACT_MAX_SIZE_VALUE		0xffffffff
+#define SEG_CONTRACT_NO_FRAGMENTATION	SEG_CONTRACT_MAX_SIZE_VALUE
+
+/**
+ * Interface for a PA-TNC attribute segmentation contract
+ *
+ */
+struct seg_contract_t {
+
+	/**
+	 * Get the PA-TNC message type.
+	 *
+	 * @return					PA-TNC Message type
+	 */
+	pen_type_t (*get_msg_type)(seg_contract_t *this);
+
+	/**
+	 * Set maximum PA-TNC attribute and segment size in octets
+	 *
+	 * @param max_attr_size	Maximum PA-TNC attribute size in octets
+	 * @param max_seg_size	Maximum PA-TNC attribute segment size in octets
+	 */
+	void (*set_max_size)(seg_contract_t *this, uint32_t max_attr_size,
+											   uint32_t max_seg_size);
+
+	/**
+	 * Get maximum PA-TNC attribute and segment size in octets
+	 *
+	 * @param max_attr_size	Maximum PA-TNC attribute size in octets
+	 * @param max_seg_size	Maximum PA-TNC attribute segment size in octets
+	 */
+	void (*get_max_size)(seg_contract_t *this, uint32_t *max_attr_size,
+											   uint32_t *max_seg_size);
+
+	/**
+	 * Check if a PA-TNC attribute must be segmented or is oversized
+	 *
+	 * @param attr			PA-TNC attribute to be checked
+	 * @param oversize		PA-TNC attribute is larger than maximum size
+	 * @return				TRUE if PA-TNC attribute must be segmented
+	 */
+	bool (*check_size)(seg_contract_t *this, pa_tnc_attr_t *attr,
+											 bool *oversize);
+
+	/**
+	 * Generate first segment of a PA-TNC attribute according to the contract
+	 *
+	 * @param attr			PA-TNC attribute to be segmented
+	 * @return				First segment envelope attribute
+	 */
+	pa_tnc_attr_t* (*first_segment)(seg_contract_t *this, pa_tnc_attr_t *attr);
+
+	/**
+	 * Generate next segment of a PA-TNC attribute according to the contract
+	 *
+	 * @param base_attr_id	Base Attribute ID
+	 * @return				Next segment envelope attribute
+	 */
+	pa_tnc_attr_t* (*next_segment)(seg_contract_t *this, uint32_t base_attr_id);
+
+	/**
+	 * Add an attribute segments until the PA-TNC attribute is reconstructed
+	 *
+	 * @param attr			Segment envelope attribute
+	 * @param error			Error attribute if an error occurred or NULL
+	 * @param more			Need more segments
+	 * @return				Completed PA-TNC attribute or NULL
+	 */
+	pa_tnc_attr_t* (*add_segment)(seg_contract_t *this,
+								 pa_tnc_attr_t *attr, pa_tnc_attr_t **error,
+								 bool *more);
+
+	/**
+	 * Get contract role
+	 *
+	 * @return				TRUE:  contracting party (issuer),
+	 *						FALSE: contracted party 
+	 */
+	bool (*is_issuer)(seg_contract_t *this);
+
+	/**
+	 * Is this a null contract ?
+	 *
+	 * @return				TRUE if null contract
+	 */
+	bool (*is_null)(seg_contract_t *this);
+
+	/**
+	 * Get an info string about the contract
+	 *
+	 * @param buf			String buffer of at least size len
+	 * @param len			Size of string buffer
+	 * @param request		TRUE if contract request, FALSE if response
+	 */
+	void (*get_info_string)(seg_contract_t *this, char *buf, size_t len,
+							bool request);
+
+	/**
+	 * Destroys a seg_contract_t object.
+	 */
+	void (*destroy)(seg_contract_t *this);
+};
+
+/**
+ * Create a PA-TNC attribute segmentation contract 
+ *
+ * @param msg_type			PA-TNC message type
+ * @param max_attr_size		Maximum PA-TNC attribute size in octets
+ * @param max_seg_size		Maximum PA-TNC attribute segment size in octets
+ * @param is_issuer			TRUE if issuer of the contract
+ * @param issuer_id			IMC or IMV ID of issuer
+ * @param is_imc			TRUE if IMC, FALSE if IMV
+ */
+seg_contract_t* seg_contract_create(pen_type_t msg_type,
+									uint32_t max_attr_size,
+									uint32_t max_seg_size,
+									bool is_issuer, TNC_UInt32 issuer_id,
+									bool is_imc);
+
+#endif /** SEG_CONTRACT_H_ @}*/
diff --git a/src/libimcv/seg/seg_contract_manager.c b/src/libimcv/seg/seg_contract_manager.c
new file mode 100644
index 000000000..d099436fc
--- /dev/null
+++ b/src/libimcv/seg/seg_contract_manager.c
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "seg_contract_manager.h"
+
+typedef struct private_seg_contract_manager_t private_seg_contract_manager_t;
+
+/**
+ * Private data of a seg_contract_manager_t object.
+ *
+ */
+struct private_seg_contract_manager_t {
+
+	/**
+	 * Public seg_contract_manager_t interface.
+	 */
+	seg_contract_manager_t public;
+
+	/**
+	 * List of PA-TNC segmentation contracts
+	 */
+	linked_list_t *contracts;
+
+};
+
+METHOD(seg_contract_manager_t, add_contract, void,
+	private_seg_contract_manager_t *this, seg_contract_t *contract)
+{
+	this->contracts->insert_last(this->contracts, contract);
+}
+
+METHOD(seg_contract_manager_t, get_contract, seg_contract_t*,
+	private_seg_contract_manager_t *this, pen_type_t msg_type, bool is_issuer)
+{
+	enumerator_t *enumerator;
+	seg_contract_t *contract, *found = NULL;
+
+	enumerator = this->contracts->create_enumerator(this->contracts);
+	while (enumerator->enumerate(enumerator, &contract))
+	{
+		if (contract->is_issuer(contract) == is_issuer &&
+			pen_type_equals(contract->get_msg_type(contract), msg_type))
+		{
+			found = contract;
+			break;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	return found;
+}
+
+METHOD(seg_contract_manager_t, destroy, void,
+	private_seg_contract_manager_t *this)
+{
+	this->contracts->destroy_offset(this->contracts,
+									offsetof(seg_contract_t, destroy));
+	free(this);
+}
+
+/**
+ * See header
+ */
+seg_contract_manager_t *seg_contract_manager_create(void)
+{
+	private_seg_contract_manager_t *this;
+
+	INIT(this,
+		.public = {
+			.add_contract = _add_contract,
+			.get_contract = _get_contract,
+			.destroy = _destroy,
+		},
+		.contracts = linked_list_create(),
+	);
+
+	return &this->public;
+}
+
diff --git a/src/libimcv/seg/seg_contract_manager.h b/src/libimcv/seg/seg_contract_manager.h
new file mode 100644
index 000000000..355822d99
--- /dev/null
+++ b/src/libimcv/seg/seg_contract_manager.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup seg_contract_manager seg_contract_manager
+ * @{ @ingroup libimcv
+ */
+
+#ifndef SEG_CONTRACT_MANAGER_H_
+#define SEG_CONTRACT_MANAGER_H_
+
+typedef struct seg_contract_manager_t seg_contract_manager_t;
+
+#include "seg_contract.h"
+
+/**
+ * Interface for a PA-TNC attribute segmentation contract manager
+ *
+ */
+struct seg_contract_manager_t {
+
+	/**
+	 * Add segmentation contract
+	 *
+	 * @param contract			Segmentation contract to be added
+	 */
+	void (*add_contract)(seg_contract_manager_t *this, seg_contract_t *contract);
+
+	/**
+	 * Get segmentation contract
+	 *
+	 * @param msg_type			PA-TNC message type governed by contract
+	 * @param is_issuer			If TRUE get only issuer contracts
+	 */
+	seg_contract_t* (*get_contract)(seg_contract_manager_t *this,
+									pen_type_t msg_type, bool is_issuer);
+
+	/**
+	 * Destroys a seg_contract_manager_t object.
+	 */
+	void (*destroy)(seg_contract_manager_t *this);
+};
+
+/**
+ * Create a PA-TNC attribute segmentation contract manager
+ */
+seg_contract_manager_t* seg_contract_manager_create();
+
+#endif /** SEG_CONTRACT_MANAGER_H_ @}*/
diff --git a/src/libimcv/seg/seg_env.c b/src/libimcv/seg/seg_env.c
new file mode 100644
index 000000000..1f4cfc53f
--- /dev/null
+++ b/src/libimcv/seg/seg_env.c
@@ -0,0 +1,261 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "seg_env.h"
+
+#include "imcv.h"
+#include "pa_tnc/pa_tnc_msg.h"
+
+#include <utils/debug.h>
+#include <bio/bio_reader.h>
+#include <bio/bio_writer.h>
+
+#include <tcg/seg/tcg_seg_attr_seg_env.h>
+
+#define BASE_ATTR_ID_PREFIX	0xFF
+
+typedef struct private_seg_env_t private_seg_env_t;
+
+/**
+ * Private data of a seg_env_t object.
+ */
+struct private_seg_env_t {
+
+	/**
+	 * Public seg_env_t interface.
+	 */
+	seg_env_t public;
+
+	/**
+	 * Base Attribute ID
+	 */
+	uint32_t base_attr_id;
+
+	/**
+	 * Base Attribute
+	 */
+	pa_tnc_attr_t *base_attr;
+
+	/**
+	 * Maximum PA-TNC attribute segment size
+	 */
+	uint32_t max_seg_size;
+
+	/**
+	 * TRUE if attribute is assembled from data
+	 */
+	bool from_data;
+
+	/**
+	 * Remaining attribute data to be sent or received data being accumulated
+	 */
+	chunk_t data;
+
+};
+
+METHOD(seg_env_t, get_base_attr_id, uint32_t,
+	private_seg_env_t *this)
+{
+	return this->base_attr_id;
+}
+
+METHOD(seg_env_t, get_base_attr, pa_tnc_attr_t*,
+	private_seg_env_t *this, pa_tnc_attr_t** error)
+{
+	*error = NULL;
+
+	if (!this->base_attr)
+	{
+		bio_writer_t *writer;
+		bio_reader_t *reader;
+		chunk_t msg_info;
+		uint32_t offset = 0;
+
+		writer = bio_writer_create(8);
+		writer->write_uint8 (writer, PA_TNC_VERSION);
+		writer->write_uint24(writer, PA_TNC_RESERVED);
+		writer->write_uint8 (writer, BASE_ATTR_ID_PREFIX);
+		writer->write_uint24(writer, this->base_attr_id);
+		msg_info = writer->extract_buf(writer);
+		writer->destroy(writer);
+
+		reader = bio_reader_create(this->data);
+		this->base_attr = imcv_pa_tnc_attributes->create(imcv_pa_tnc_attributes,
+										reader, &offset, msg_info, error);
+		chunk_free(&msg_info);
+		reader->destroy(reader);
+	}
+		
+	return this->base_attr ? this->base_attr->get_ref(this->base_attr) : NULL;
+}
+
+METHOD(seg_env_t, first_segment, pa_tnc_attr_t*,
+	private_seg_env_t *this)
+{
+	pa_tnc_attr_t *seg_env_attr;
+	bio_writer_t *writer;
+	pen_type_t type;
+	chunk_t segment_data, value;
+	uint8_t flags, seg_env_flags;
+
+	/* get components of base attribute header and data */
+	flags = this->base_attr->get_noskip_flag(this->base_attr) ?
+				PA_TNC_ATTR_FLAG_NOSKIP : PA_TNC_ATTR_FLAG_NONE;
+	type = this->base_attr->get_type(this->base_attr);
+
+	/* attribute data going into the first segment */
+	segment_data = this->data;
+	segment_data.len = this->max_seg_size - PA_TNC_ATTR_HEADER_SIZE;
+
+	/* build encoding of the base attribute header and first segment data */
+	writer = bio_writer_create(this->max_seg_size);
+	writer->write_uint8 (writer, flags);
+	writer->write_uint24(writer, type.vendor_id);
+	writer->write_uint32(writer, type.type);
+	writer->write_uint32(writer, PA_TNC_ATTR_HEADER_SIZE + this->data.len);
+	writer->write_data  (writer, segment_data);
+	value = writer->extract_buf(writer);
+	writer->destroy(writer);
+	this->data = chunk_skip(this->data, segment_data.len);
+
+	DBG2(DBG_TNC, "creating first segment for base attribute ID %d (%d bytes)",
+		 this->base_attr_id, this->max_seg_size);
+
+	seg_env_flags = SEG_ENV_FLAG_START | SEG_ENV_FLAG_MORE;
+	seg_env_attr = tcg_seg_attr_seg_env_create(value, seg_env_flags,
+											   this->base_attr_id);
+	chunk_free(&value);
+
+	return seg_env_attr;
+}
+
+METHOD(seg_env_t, next_segment, pa_tnc_attr_t*,
+	private_seg_env_t *this, bool *last)
+{
+	pa_tnc_attr_t *seg_env_attr;
+	chunk_t segment_data;
+	uint8_t seg_env_flags;
+	bool is_last_segment;
+
+	if (this->data.len == 0)
+	{
+		/* no more attribute data to segment available */
+		return NULL;
+	}
+
+	/* attribute data going into the next segment */
+	segment_data = this->data;
+	segment_data.len = min(this->max_seg_size, this->data.len);
+	this->data = chunk_skip(this->data, segment_data.len);
+
+	is_last_segment = (this->data.len == 0);
+	if (last)
+	{
+		*last = is_last_segment;
+	}
+	DBG2(DBG_TNC, "creating %s segment for base attribute ID %d (%d bytes)",
+				   is_last_segment ? "last" : "next", this->base_attr_id,
+				   segment_data.len);
+
+	seg_env_flags = is_last_segment ? SEG_ENV_FLAG_NONE : SEG_ENV_FLAG_MORE;
+	seg_env_attr = tcg_seg_attr_seg_env_create(segment_data, seg_env_flags,
+											   this->base_attr_id);
+
+	return seg_env_attr;
+}
+
+METHOD(seg_env_t, add_segment, void,
+	private_seg_env_t *this, chunk_t segment_data)
+{
+	this->data = chunk_cat("mc", this->data, segment_data);
+}
+
+METHOD(seg_env_t, destroy, void,
+	private_seg_env_t *this)
+{
+	if (this->from_data)
+	{
+		chunk_free(&this->data);
+	}
+	DESTROY_IF(this->base_attr);
+	free(this);
+}
+
+/**
+ * See header
+ */
+seg_env_t *seg_env_create(uint32_t base_attr_id, pa_tnc_attr_t *base_attr,
+						  uint32_t max_seg_size)
+{
+	private_seg_env_t *this;
+	chunk_t value;
+
+	base_attr->build(base_attr);
+	value = base_attr->get_value(base_attr);
+
+	/**
+	 * The PA-TNC attribute header must not be segmented and
+	 * there must be at least a first and one next segment
+	 */
+	if (max_seg_size <  PA_TNC_ATTR_HEADER_SIZE ||
+		max_seg_size >= PA_TNC_ATTR_HEADER_SIZE + value.len)
+	{
+		return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.get_base_attr_id = _get_base_attr_id,
+			.get_base_attr = _get_base_attr,
+			.first_segment = _first_segment,
+			.next_segment = _next_segment,
+			.add_segment = _add_segment,
+			.destroy = _destroy,
+		},
+		.base_attr_id = base_attr_id,
+		.base_attr = base_attr->get_ref(base_attr),
+		.max_seg_size = max_seg_size,
+		.data = base_attr->get_value(base_attr),
+	);
+
+	return &this->public;
+}
+
+/**
+ * See header
+ */
+seg_env_t *seg_env_create_from_data(uint32_t base_attr_id, chunk_t data,
+									uint32_t max_seg_size)
+{
+	private_seg_env_t *this;
+
+	INIT(this,
+		.public = {
+			.get_base_attr_id = _get_base_attr_id,
+			.get_base_attr = _get_base_attr,
+			.first_segment = _first_segment,
+			.next_segment = _next_segment,
+			.add_segment = _add_segment,
+			.destroy = _destroy,
+		},
+		.base_attr_id = base_attr_id,
+		.max_seg_size = max_seg_size,
+		.data = chunk_clone(data),
+		.from_data = TRUE,
+	);
+
+	return &this->public;
+}
+
diff --git a/src/libimcv/seg/seg_env.h b/src/libimcv/seg/seg_env.h
new file mode 100644
index 000000000..0dcefdde8
--- /dev/null
+++ b/src/libimcv/seg/seg_env.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2014 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup seg_env seg_env
+ * @{ @ingroup libimcv
+ */
+
+#ifndef SEG_ENV_H_
+#define SEG_ENV_H_
+
+typedef struct seg_env_t seg_env_t;
+typedef enum seg_env_flags_t seg_env_flags_t;
+
+#include <library.h>
+
+#include <pa_tnc/pa_tnc_attr.h>
+
+/**
+ * Segment Envelope flags
+ */
+enum seg_env_flags_t {
+	SEG_ENV_FLAG_NONE =	  0,
+	SEG_ENV_FLAG_MORE =	 (1<<7),
+	SEG_ENV_FLAG_START = (1<<6)
+};
+
+/**
+ * Interface for a PA-TNC attribute segment envelope object
+ */
+struct seg_env_t {
+
+	/**
+	 * Get Base Attribute ID
+	 *
+	 * @return				Base Attribute ID
+	 */
+	uint32_t (*get_base_attr_id)(seg_env_t *this);
+
+	/**
+	 * Get Base Attribute
+	 *
+	 * @param error			Error attribute if an error occurred or NULL
+	 * @return				Base Attribute (must be destroyed) or NULL
+	 */
+	pa_tnc_attr_t* (*get_base_attr)(seg_env_t *this, pa_tnc_attr_t **error);
+
+	/**
+	 * Generate the first segment envelope of the base attribute
+	 *
+	 * @return				First attribute segment envelope
+	 */
+	pa_tnc_attr_t* (*first_segment)(seg_env_t *this);
+
+	/**
+	 * Generate the next segment envelope of the base attribute
+	 *
+	 * @param last			TRUE if last segment
+	 * @return				Next attribute segment envelope
+	 */
+	pa_tnc_attr_t* (*next_segment)(seg_env_t *this, bool *last);
+
+	/**
+	 * Generate the first segment envelope of the base attribute
+	 *
+	 * @param segment		Attribute segment to be added
+	 */
+	void (*add_segment)(seg_env_t *this, chunk_t segment);
+
+	/**
+	 * Destroys a seg_env_t object.
+	 */
+	void (*destroy)(seg_env_t *this);
+};
+
+/**
+ * Create a PA-TNC attribute segment envelope object
+ *
+ * @param base_attr_id		Base Attribute ID
+ * @param base_attr			Base Attribute to be segmented
+ * @param max_seg_size		Maximum segment size
+ */
+seg_env_t* seg_env_create(uint32_t base_attr_id, pa_tnc_attr_t *base_attr,
+						  uint32_t max_seg_size);
+
+/**
+ * Create a PA-TNC attribute segment envelope object
+ *
+ * @param base_attr_id		Base Attribute ID
+ * @param data				First attribute segment
+ * @param max_seg_size		Maximum segment size
+ */
+seg_env_t* seg_env_create_from_data(uint32_t base_attr_id, chunk_t data,
+									uint32_t max_seg_size);
+
+#endif /** SEG_ENV_H_ @}*/