Moving charon to libcharon.

1 files changed, 888 insertions, 0 deletions

diff --git a/src/libcharon/encoding/generator.c b/src/libcharon/encoding/generator.c
new file mode 100644
index 000000000..6485da492
--- /dev/null
+++ b/src/libcharon/encoding/generator.c
@@ -0,0 +1,888 @@
+/*
+ * Copyright (C) 2005-2009 Martin Willi
+ * Copyright (C) 2005 Jan Hutter
+ * 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 <stdlib.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+
+#include "generator.h"
+
+#include <library.h>
+#include <daemon.h>
+#include <utils/linked_list.h>
+#include <encoding/payloads/payload.h>
+#include <encoding/payloads/proposal_substructure.h>
+#include <encoding/payloads/transform_substructure.h>
+#include <encoding/payloads/sa_payload.h>
+#include <encoding/payloads/ke_payload.h>
+#include <encoding/payloads/notify_payload.h>
+#include <encoding/payloads/nonce_payload.h>
+#include <encoding/payloads/id_payload.h>
+#include <encoding/payloads/auth_payload.h>
+#include <encoding/payloads/cert_payload.h>
+#include <encoding/payloads/certreq_payload.h>
+#include <encoding/payloads/ts_payload.h>
+#include <encoding/payloads/delete_payload.h>
+#include <encoding/payloads/vendor_id_payload.h>
+#include <encoding/payloads/cp_payload.h>
+#include <encoding/payloads/configuration_attribute.h>
+#include <encoding/payloads/eap_payload.h>
+
+
+typedef struct private_generator_t private_generator_t;
+
+/**
+ * Private part of a generator_t object.
+ */
+struct private_generator_t {
+	/**
+	 * Public part of a generator_t object.
+	 */
+	 generator_t public;
+
+	/**
+	 * Buffer used to generate the data into.
+	 */
+	u_int8_t *buffer;
+
+	/**
+	 * Current write position in buffer (one byte aligned).
+	 */
+	u_int8_t *out_position;
+
+	/**
+	 * Position of last byte in buffer.
+	 */
+	u_int8_t *roof_position;
+
+	/**
+	 * Current bit writing to in current byte (between 0 and 7).
+	 */
+	u_int8_t current_bit;
+
+	/**
+	 * Associated data struct to read informations from.
+	 */
+	void *data_struct;
+
+	/*
+	 * Last payload length position offset in the buffer.
+	 */
+	u_int32_t last_payload_length_position_offset;
+
+	/**
+	 * Offset of the header length field in the buffer.
+	 */
+	u_int32_t header_length_position_offset;
+
+	/**
+	 * Last SPI size.
+	 */
+	u_int8_t last_spi_size;
+
+	/**
+	 * Attribute format of the last generated transform attribute.
+	 *
+	 * Used to check if a variable value field is used or not for
+	 * the transform attribute value.
+	 */
+	bool attribute_format;
+
+	/**
+	 * Depending on the value of attribute_format this field is used
+	 * to hold the length of the transform attribute in bytes.
+	 */
+	u_int16_t attribute_length;
+};
+
+/**
+ * Get size of current buffer in bytes.
+ */
+static int get_size(private_generator_t *this)
+{
+	return this->roof_position - this->buffer;
+}
+
+/**
+ * Get free space of current buffer in bytes.
+ */
+static int get_space(private_generator_t *this)
+{
+	return this->roof_position - this->out_position;
+}
+
+/**
+ * Get length of data in buffer (in bytes).
+ */
+static int get_length(private_generator_t *this)
+{
+	return this->out_position - this->buffer;
+}
+
+/**
+ * Get current offset in buffer (in bytes).
+ */
+static u_int32_t get_offset(private_generator_t *this)
+{
+	return this->out_position - this->buffer;
+}
+
+/**
+ * Makes sure enough space is available in buffer to store amount of bits.
+ */
+static void make_space_available(private_generator_t *this, int bits)
+{
+	while ((get_space(this) * 8 - this->current_bit) < bits)
+	{
+		int old_buffer_size, new_buffer_size, out_position_offset;
+
+		old_buffer_size = get_size(this);
+		new_buffer_size = old_buffer_size + GENERATOR_DATA_BUFFER_INCREASE_VALUE;
+		out_position_offset = this->out_position - this->buffer;
+
+		DBG2(DBG_ENC, "increasing gen buffer from %d to %d byte",
+			 old_buffer_size, new_buffer_size);
+
+		this->buffer = realloc(this->buffer,new_buffer_size);
+		this->out_position = (this->buffer + out_position_offset);
+		this->roof_position = (this->buffer + new_buffer_size);
+	}
+}
+
+/**
+ * Writes a specific amount of byte into the buffer.
+ */
+static void write_bytes_to_buffer(private_generator_t *this, void *bytes,
+								  int number_of_bytes)
+{
+	int i;
+	u_int8_t *read_position = (u_int8_t *)bytes;
+
+	make_space_available(this, number_of_bytes * 8);
+
+	for (i = 0; i < number_of_bytes; i++)
+	{
+		*(this->out_position) = *(read_position);
+		read_position++;
+		this->out_position++;
+	}
+}
+
+/**
+ * Writes a specific amount of byte into the buffer at a specific offset.
+ */
+static void write_bytes_to_buffer_at_offset(private_generator_t *this,
+						void *bytes, int number_of_bytes, u_int32_t offset)
+{
+	int i;
+	u_int8_t *read_position = (u_int8_t *)bytes;
+	u_int8_t *write_position;
+	u_int32_t free_space_after_offset = get_size(this) - offset;
+
+	/* check first if enough space for new data is available */
+	if (number_of_bytes > free_space_after_offset)
+	{
+		make_space_available(this,
+							 (number_of_bytes - free_space_after_offset) * 8);
+	}
+
+	write_position = this->buffer + offset;
+	for (i = 0; i < number_of_bytes; i++)
+	{
+		*write_position = *read_position;
+		read_position++;
+		write_position++;
+	}
+}
+
+/**
+ * Generates a U_INT-Field type and writes it to buffer.
+ */
+static void generate_u_int_type(private_generator_t *this,
+								encoding_type_t int_type,u_int32_t offset)
+{
+	int number_of_bits = 0;
+
+	/* find out number of bits of each U_INT type to check for enough space */
+	switch (int_type)
+	{
+		case U_INT_4:
+			number_of_bits = 4;
+			break;
+		case TS_TYPE:
+		case U_INT_8:
+			number_of_bits = 8;
+			break;
+		case U_INT_16:
+		case CONFIGURATION_ATTRIBUTE_LENGTH:
+			number_of_bits = 16;
+			break;
+		case U_INT_32:
+			number_of_bits = 32;
+			break;
+		case ATTRIBUTE_TYPE:
+			number_of_bits = 15;
+			break;
+		case IKE_SPI:
+			number_of_bits = 64;
+			break;
+		default:
+			DBG1(DBG_ENC, "U_INT Type %N is not supported",
+				 encoding_type_names, int_type);
+			return;
+	}
+	if ((number_of_bits % 8) == 0 && this->current_bit != 0)
+	{
+		DBG1(DBG_ENC, "U_INT Type %N is not 8 Bit aligned",
+			 encoding_type_names, int_type);
+		return;
+	}
+
+	make_space_available(this, number_of_bits);
+	switch (int_type)
+	{
+		case U_INT_4:
+		{
+			u_int8_t high, low;
+
+			if (this->current_bit == 0)
+			{
+				/* high of current byte in buffer has to be set to the new value*/
+				high = *((u_int8_t *)(this->data_struct + offset)) << 4;
+				/* low in buffer is not changed */
+				low = *(this->out_position) & 0x0F;
+				/* high is set, low_val is not changed */
+				*(this->out_position) = high | low;
+				DBG3(DBG_ENC, "   => %d", *(this->out_position));
+				/* write position is not changed, just bit position is moved */
+				this->current_bit = 4;
+			}
+			else if (this->current_bit == 4)
+			{
+				/* high in buffer is not changed */
+				high = *(this->out_position) & 0xF0;
+				/* low of current byte in buffer has to be set to the new value*/
+				low = *((u_int8_t *)(this->data_struct + offset)) & 0x0F;
+				*(this->out_position) = high | low;
+				DBG3(DBG_ENC, "   => %d", *(this->out_position));
+				this->out_position++;
+				this->current_bit = 0;
+			}
+			else
+			{
+				DBG1(DBG_ENC, "U_INT_4 Type is not 4 Bit aligned");
+				/* 4 Bit integers must have a 4 bit alignment */
+				return;
+			}
+			break;
+		}
+		case TS_TYPE:
+		case U_INT_8:
+		{
+			/* 8 bit values are written as they are */
+			*this->out_position = *((u_int8_t *)(this->data_struct + offset));
+			DBG3(DBG_ENC, "   => %d", *(this->out_position));
+			this->out_position++;
+			break;
+		}
+		case ATTRIBUTE_TYPE:
+		{
+			u_int8_t attribute_format_flag;
+			u_int16_t val;
+
+			/* attribute type must not change first bit of current byte */
+			if (this->current_bit != 1)
+			{
+				DBG1(DBG_ENC, "ATTRIBUTE FORMAT flag is not set");
+				return;
+			}
+			attribute_format_flag = *(this->out_position) & 0x80;
+			/* get attribute type value as 16 bit integer*/
+			val = *((u_int16_t*)(this->data_struct + offset));
+			/* unset most significant bit */
+			val &= 0x7FFF;
+			if (attribute_format_flag)
+			{
+				val |= 0x8000;
+			}
+			val = htons(val);
+			DBG3(DBG_ENC, "   => %d", val);
+			/* write bytes to buffer (set bit is overwritten) */
+			write_bytes_to_buffer(this, &val, sizeof(u_int16_t));
+			this->current_bit = 0;
+			break;
+
+		}
+		case U_INT_16:
+		case CONFIGURATION_ATTRIBUTE_LENGTH:
+		{
+			u_int16_t val = htons(*((u_int16_t*)(this->data_struct + offset)));
+			DBG3(DBG_ENC, "   => %b", &val, sizeof(u_int16_t));
+			write_bytes_to_buffer(this, &val, sizeof(u_int16_t));
+			break;
+		}
+		case U_INT_32:
+		{
+			u_int32_t val = htonl(*((u_int32_t*)(this->data_struct + offset)));
+			DBG3(DBG_ENC, "   => %b", &val, sizeof(u_int32_t));
+			write_bytes_to_buffer(this, &val, sizeof(u_int32_t));
+			break;
+		}
+		case IKE_SPI:
+		{
+			/* 64 bit are written as-is, no host order conversion */
+			write_bytes_to_buffer(this, this->data_struct + offset,
+								  sizeof(u_int64_t));
+			DBG3(DBG_ENC, "   => %b", this->data_struct + offset,
+				 sizeof(u_int64_t));
+			break;
+		}
+		default:
+		{
+			DBG1(DBG_ENC, "U_INT Type %N is not supported",
+				 encoding_type_names, int_type);
+			return;
+		}
+	}
+}
+
+/**
+ * Generate a reserved bit or byte
+ */
+static void generate_reserved_field(private_generator_t *this, int bits)
+{
+	/* only one bit or 8 bit fields are supported */
+	if (bits != 1 && bits != 8)
+	{
+		DBG1(DBG_ENC, "reserved field of %d bits cannot be generated", bits);
+		return ;
+	}
+	make_space_available(this, bits);
+
+	if (bits == 1)
+	{
+		u_int8_t reserved_bit = ~(1 << (7 - this->current_bit));
+
+		*(this->out_position) = *(this->out_position) & reserved_bit;
+		if (this->current_bit == 0)
+		{
+			/* memory must be zero */
+			*(this->out_position) = 0x00;
+		}
+		this->current_bit++;
+		if (this->current_bit >= 8)
+		{
+			this->current_bit = this->current_bit % 8;
+			this->out_position++;
+		}
+	}
+	else
+	{
+		if (this->current_bit > 0)
+		{
+			DBG1(DBG_ENC, "reserved field cannot be written cause "
+				 "alignement of current bit is %d", this->current_bit);
+			return;
+		}
+		*(this->out_position) = 0x00;
+		this->out_position++;
+	}
+}
+
+/**
+ * Generate a FLAG filed
+ */
+static void generate_flag(private_generator_t *this, u_int32_t offset)
+{
+	u_int8_t flag_value;
+	u_int8_t flag;
+
+	flag_value = (*((bool *) (this->data_struct + offset))) ? 1 : 0;
+	/* get flag position */
+	flag = (flag_value << (7 - this->current_bit));
+
+	/* make sure one bit is available in buffer */
+	make_space_available(this, 1);
+	if (this->current_bit == 0)
+	{
+		/* memory must be zero */
+		*(this->out_position) = 0x00;
+	}
+
+	*(this->out_position) = *(this->out_position) | flag;
+	DBG3(DBG_ENC, "   => %d", *this->out_position);
+
+	this->current_bit++;
+	if (this->current_bit >= 8)
+	{
+		this->current_bit = this->current_bit % 8;
+		this->out_position++;
+	}
+}
+
+/**
+ * Generates a bytestream from a chunk_t.
+ */
+static void generate_from_chunk(private_generator_t *this, u_int32_t offset)
+{
+	chunk_t *value;
+
+	if (this->current_bit != 0)
+	{
+		DBG1(DBG_ENC, "can not generate a chunk at Bitpos %d", this->current_bit);
+		return ;
+	}
+
+	value = (chunk_t *)(this->data_struct + offset);
+	DBG3(DBG_ENC, "   => %B", value);
+
+	write_bytes_to_buffer(this, value->ptr, value->len);
+}
+
+/**
+ * Implementation of private_generator_t.write_to_chunk.
+ */
+static void write_to_chunk(private_generator_t *this,chunk_t *data)
+{
+	int data_length = get_length(this);
+	u_int32_t header_length_field = data_length;
+
+	/* write length into header length field */
+	if (this->header_length_position_offset > 0)
+	{
+		u_int32_t val = htonl(header_length_field);
+		write_bytes_to_buffer_at_offset(this, &val, sizeof(u_int32_t),
+										this->header_length_position_offset);
+	}
+
+	if (this->current_bit > 0)
+	{
+		data_length++;
+	}
+	*data = chunk_alloc(data_length);
+	memcpy(data->ptr, this->buffer, data_length);
+
+	DBG3(DBG_ENC, "generated data of this generator %B", data);
+}
+
+/**
+ * Implementation of private_generator_t.generate_payload.
+ */
+static void generate_payload (private_generator_t *this,payload_t *payload)
+{
+	int i, offset_start;
+	size_t rule_count;
+	encoding_rule_t *rules;
+	payload_type_t payload_type;
+
+	this->data_struct = payload;
+	payload_type = payload->get_type(payload);
+	/* spi size has to get reseted */
+	this->last_spi_size = 0;
+
+	offset_start = this->out_position - this->buffer;
+
+	DBG2(DBG_ENC, "generating payload of type %N",
+		 payload_type_names, payload_type);
+
+	/* each payload has its own encoding rules */
+	payload->get_encoding_rules(payload, &rules, &rule_count);
+
+	for (i = 0; i < rule_count;i++)
+	{
+		DBG2(DBG_ENC, "  generating rule %d %N",
+			 i, encoding_type_names, rules[i].type);
+		switch (rules[i].type)
+		{
+			case U_INT_4:
+			case U_INT_8:
+			case U_INT_16:
+			case U_INT_32:
+			case IKE_SPI:
+			case TS_TYPE:
+			case ATTRIBUTE_TYPE:
+			case CONFIGURATION_ATTRIBUTE_LENGTH:
+			{
+				generate_u_int_type(this, rules[i].type, rules[i].offset);
+				break;
+			}
+			case RESERVED_BIT:
+			{
+				generate_reserved_field(this, 1);
+				break;
+			}
+			case RESERVED_BYTE:
+			{
+				generate_reserved_field(this, 8);
+				break;
+			}
+			case FLAG:
+			{
+				generate_flag(this, rules[i].offset);
+				break;
+			}
+			case PAYLOAD_LENGTH:
+			{
+				this->last_payload_length_position_offset = get_offset(this);
+				generate_u_int_type(this, U_INT_16,rules[i].offset);
+				break;
+			}
+			case HEADER_LENGTH:
+			{
+				this->header_length_position_offset = get_offset(this);
+				generate_u_int_type(this ,U_INT_32, rules[i].offset);
+				break;
+			}
+			case SPI_SIZE:
+				generate_u_int_type(this, U_INT_8, rules[i].offset);
+				this->last_spi_size = *((u_int8_t *)(this->data_struct +
+													 rules[i].offset));
+				break;
+			case ADDRESS:
+			{
+				generate_from_chunk(this, rules[i].offset);
+				break;
+			}
+			case SPI:
+			{
+				generate_from_chunk(this, rules[i].offset);
+				break;
+			}
+			case KEY_EXCHANGE_DATA:
+			case NOTIFICATION_DATA:
+			case NONCE_DATA:
+			case ID_DATA:
+			case AUTH_DATA:
+			case CERT_DATA:
+			case CERTREQ_DATA:
+			case SPIS:
+			case CONFIGURATION_ATTRIBUTE_VALUE:
+			case VID_DATA:
+			case EAP_DATA:
+			{
+				u_int32_t payload_length_position_offset;
+				u_int16_t length_of_payload;
+				u_int16_t header_length = 0;
+				u_int16_t length_in_network_order;
+
+				switch(rules[i].type)
+				{
+					case KEY_EXCHANGE_DATA:
+						header_length = KE_PAYLOAD_HEADER_LENGTH;
+						break;
+					case NOTIFICATION_DATA:
+						header_length = NOTIFY_PAYLOAD_HEADER_LENGTH +
+														this->last_spi_size;
+						break;
+					case NONCE_DATA:
+						header_length = NONCE_PAYLOAD_HEADER_LENGTH;
+						break;
+					case ID_DATA:
+						header_length = ID_PAYLOAD_HEADER_LENGTH;
+						break;
+					case AUTH_DATA:
+						header_length = AUTH_PAYLOAD_HEADER_LENGTH;
+						break;
+					case CERT_DATA:
+						header_length = CERT_PAYLOAD_HEADER_LENGTH;
+						break;
+					case CERTREQ_DATA:
+						header_length = CERTREQ_PAYLOAD_HEADER_LENGTH;
+						break;
+					case SPIS:
+						header_length = DELETE_PAYLOAD_HEADER_LENGTH;
+						break;
+					case VID_DATA:
+						header_length = VENDOR_ID_PAYLOAD_HEADER_LENGTH;
+						break;
+					case CONFIGURATION_ATTRIBUTE_VALUE:
+						header_length = CONFIGURATION_ATTRIBUTE_HEADER_LENGTH;
+						break;
+					case EAP_DATA:
+						header_length = EAP_PAYLOAD_HEADER_LENGTH;
+						break;
+					default:
+						break;
+				}
+				generate_from_chunk(this, rules[i].offset);
+
+				payload_length_position_offset =
+									this->last_payload_length_position_offset;
+
+				length_of_payload = header_length +
+						((chunk_t *)(this->data_struct + rules[i].offset))->len;
+
+				length_in_network_order = htons(length_of_payload);
+				write_bytes_to_buffer_at_offset(this, &length_in_network_order,
+							sizeof(u_int16_t), payload_length_position_offset);
+				break;
+			}
+			case PROPOSALS:
+			{
+				u_int32_t payload_length_position_offset =
+									this->last_payload_length_position_offset;
+				/* Length of SA_PAYLOAD is calculated */
+				u_int16_t length_of_sa_payload = SA_PAYLOAD_HEADER_LENGTH;
+				u_int16_t int16_val;
+				linked_list_t *proposals = *((linked_list_t **)
+										(this->data_struct + rules[i].offset));
+				iterator_t *iterator;
+				payload_t *current_proposal;
+
+				iterator = proposals->create_iterator(proposals,TRUE);
+				while (iterator->iterate(iterator, (void**)&current_proposal))
+				{
+					u_int32_t before_generate_position_offset;
+					u_int32_t after_generate_position_offset;
+
+					before_generate_position_offset = get_offset(this);
+					generate_payload(this, current_proposal);
+					after_generate_position_offset = get_offset(this);
+					length_of_sa_payload += (after_generate_position_offset -
+											 before_generate_position_offset);
+				}
+				iterator->destroy(iterator);
+
+				int16_val = htons(length_of_sa_payload);
+				write_bytes_to_buffer_at_offset(this, &int16_val,
+							sizeof(u_int16_t),payload_length_position_offset);
+				break;
+			}
+			case TRANSFORMS:
+			{
+				u_int32_t payload_length_position_offset =
+									this->last_payload_length_position_offset;
+				u_int16_t length_of_proposal =
+					PROPOSAL_SUBSTRUCTURE_HEADER_LENGTH + this->last_spi_size;
+				u_int16_t int16_val;
+				linked_list_t *transforms = *((linked_list_t **)
+										(this->data_struct + rules[i].offset));
+				iterator_t *iterator;
+				payload_t *current_transform;
+
+				iterator = transforms->create_iterator(transforms,TRUE);
+				while (iterator->iterate(iterator, (void**)&current_transform))
+				{
+					u_int32_t before_generate_position_offset;
+					u_int32_t after_generate_position_offset;
+
+					before_generate_position_offset = get_offset(this);
+					generate_payload(this, current_transform);
+					after_generate_position_offset = get_offset(this);
+
+					length_of_proposal += (after_generate_position_offset -
+										   before_generate_position_offset);
+				}
+				iterator->destroy(iterator);
+
+				int16_val = htons(length_of_proposal);
+				write_bytes_to_buffer_at_offset(this, &int16_val,
+							sizeof(u_int16_t), payload_length_position_offset);
+				break;
+			}
+			case TRANSFORM_ATTRIBUTES:
+			{
+				u_int32_t transform_length_position_offset =
+									this->last_payload_length_position_offset;
+				u_int16_t length_of_transform =
+									TRANSFORM_SUBSTRUCTURE_HEADER_LENGTH;
+				u_int16_t int16_val;
+				linked_list_t *transform_attributes =*((linked_list_t **)
+									(this->data_struct + rules[i].offset));
+				iterator_t *iterator;
+				payload_t *current_attribute;
+
+				iterator = transform_attributes->create_iterator(
+													transform_attributes, TRUE);
+				while (iterator->iterate(iterator, (void**)&current_attribute))
+				{
+					u_int32_t before_generate_position_offset;
+					u_int32_t after_generate_position_offset;
+
+					before_generate_position_offset = get_offset(this);
+					generate_payload(this, current_attribute);
+					after_generate_position_offset = get_offset(this);
+
+					length_of_transform += (after_generate_position_offset -
+											before_generate_position_offset);
+				}
+
+				iterator->destroy(iterator);
+
+				int16_val = htons(length_of_transform);
+				write_bytes_to_buffer_at_offset(this, &int16_val,
+							sizeof(u_int16_t),transform_length_position_offset);
+				break;
+			}
+			case CONFIGURATION_ATTRIBUTES:
+			{
+				u_int32_t configurations_length_position_offset =
+									this->last_payload_length_position_offset;
+				u_int16_t length_of_configurations = CP_PAYLOAD_HEADER_LENGTH;
+				u_int16_t int16_val;
+				linked_list_t *configuration_attributes = *((linked_list_t **)
+										(this->data_struct + rules[i].offset));
+				iterator_t *iterator;
+				payload_t *current_attribute;
+
+				iterator = configuration_attributes->create_iterator(
+												configuration_attributes,TRUE);
+				while (iterator->iterate(iterator, (void**)&current_attribute))
+				{
+					u_int32_t before_generate_position_offset;
+					u_int32_t after_generate_position_offset;
+
+					before_generate_position_offset = get_offset(this);
+					generate_payload(this, current_attribute);
+					after_generate_position_offset = get_offset(this);
+
+					length_of_configurations += after_generate_position_offset -
+											before_generate_position_offset;
+				}
+
+				iterator->destroy(iterator);
+
+				int16_val = htons(length_of_configurations);
+				write_bytes_to_buffer_at_offset(this, &int16_val,
+					 sizeof(u_int16_t),configurations_length_position_offset);
+				break;
+			}
+			case ATTRIBUTE_FORMAT:
+			{
+				generate_flag(this, rules[i].offset);
+				/* Attribute format is a flag which is stored in context*/
+				this->attribute_format =
+							*((bool *)(this->data_struct + rules[i].offset));
+				break;
+			}
+
+			case ATTRIBUTE_LENGTH_OR_VALUE:
+			{
+				if (this->attribute_format == FALSE)
+				{
+					generate_u_int_type(this, U_INT_16, rules[i].offset);
+					/* this field hold the length of the attribute */
+					this->attribute_length =
+						*((u_int16_t *)(this->data_struct + rules[i].offset));
+				}
+				else
+				{
+					generate_u_int_type(this, U_INT_16, rules[i].offset);
+				}
+				break;
+			}
+			case ATTRIBUTE_VALUE:
+			{
+				if (this->attribute_format == FALSE)
+				{
+					DBG2(DBG_ENC, "attribute value has not fixed size");
+					/* the attribute value is generated */
+					generate_from_chunk(this, rules[i].offset);
+				}
+				break;
+			}
+			case TRAFFIC_SELECTORS:
+			{
+				u_int32_t payload_length_position_offset =
+									this->last_payload_length_position_offset;
+				u_int16_t length_of_ts_payload = TS_PAYLOAD_HEADER_LENGTH;
+				u_int16_t int16_val;
+				linked_list_t *traffic_selectors = *((linked_list_t **)
+										(this->data_struct + rules[i].offset));
+				iterator_t *iterator;
+				payload_t *current_tss;
+
+				iterator = traffic_selectors->create_iterator(
+													traffic_selectors,TRUE);
+				while (iterator->iterate(iterator, (void **)&current_tss))
+				{
+					u_int32_t before_generate_position_offset;
+					u_int32_t after_generate_position_offset;
+
+					before_generate_position_offset = get_offset(this);
+					generate_payload(this, current_tss);
+					after_generate_position_offset = get_offset(this);
+
+					length_of_ts_payload += (after_generate_position_offset -
+											 before_generate_position_offset);
+				}
+				iterator->destroy(iterator);
+
+				int16_val = htons(length_of_ts_payload);
+				write_bytes_to_buffer_at_offset(this, &int16_val,
+							sizeof(u_int16_t),payload_length_position_offset);
+				break;
+			}
+
+			case ENCRYPTED_DATA:
+			{
+				generate_from_chunk(this, rules[i].offset);
+				break;
+			}
+			default:
+				DBG1(DBG_ENC, "field type %N is not supported",
+					 encoding_type_names, rules[i].type);
+				return;
+		}
+	}
+	DBG2(DBG_ENC, "generating %N payload finished",
+		 payload_type_names, payload_type);
+	DBG3(DBG_ENC, "generated data for this payload %b",
+		 this->buffer + offset_start,
+		 this->out_position - this->buffer - offset_start);
+}
+
+/**
+ * Implementation of generator_t.destroy.
+ */
+static status_t destroy(private_generator_t *this)
+{
+	free(this->buffer);
+	free(this);
+	return SUCCESS;
+}
+
+/*
+ * Described in header
+ */
+generator_t *generator_create()
+{
+	private_generator_t *this;
+
+	this = malloc_thing(private_generator_t);
+
+	/* initiate public functions */
+	this->public.generate_payload = (void(*)(generator_t*, payload_t *))generate_payload;
+	this->public.destroy = (void(*)(generator_t*)) destroy;
+	this->public.write_to_chunk = (void (*) (generator_t *,chunk_t *))write_to_chunk;
+
+	/* allocate memory for buffer */
+	this->buffer = malloc(GENERATOR_DATA_BUFFER_SIZE);
+
+	/* initiate private variables */
+	this->out_position = this->buffer;
+	this->roof_position = this->buffer + GENERATOR_DATA_BUFFER_SIZE;
+	this->data_struct = NULL;
+	this->current_bit = 0;
+	this->last_payload_length_position_offset = 0;
+	this->header_length_position_offset = 0;
+	this->attribute_format = FALSE;
+	this->attribute_length = 0;
+
+	return &(this->public);
+}
+