[strongswan.git] / src / charon / encoding / message.c

/**
 * @file message.c
 *
 * @brief Implementation of message_t.
 *
 */

/*
 * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
 * Copyright (C) 2005-2006 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 <printf.h>

#include "message.h"

#include <types.h>
#include <daemon.h>
#include <sa/ike_sa_id.h>
#include <encoding/generator.h>
#include <encoding/parser.h>
#include <utils/linked_list.h>
#include <encoding/payloads/encodings.h>
#include <encoding/payloads/payload.h>
#include <encoding/payloads/encryption_payload.h>
#include <encoding/payloads/unknown_payload.h>

/**
 * Max number of notify payloads per IKEv2 Message
 */
#define MAX_NOTIFY_PAYLOADS 20


typedef struct payload_rule_t payload_rule_t;

/**
 * A payload rule defines the rules for a payload
 * in a specific message rule. It defines if and how 
 * many times a payload must/can occur in a message
 * and if it must be encrypted.
 */
struct payload_rule_t {
        /**
         * Payload type.
         */
         payload_type_t payload_type;
         
         /**
          * Minimal occurence of this payload.
          */
         size_t min_occurence;

         /**
          * Max occurence of this payload.
          */
         size_t max_occurence;
         
         /**
          * TRUE if payload must be encrypted
          */
         bool encrypted;
         
         /**
          * If this payload occurs, the message rule is
          * fullfilled in any case. This applies e.g. to 
          * notify_payloads.
          */
         bool sufficient;
};

typedef struct message_rule_t message_rule_t;

/**
 * A message rule defines the kind of a message,
 * if it has encrypted contents and a list
 * of payload rules.
 * 
 */
struct message_rule_t {
        /**
         * Type of message.
         */
        exchange_type_t exchange_type;
        
        /**
         * Is message a request or response.
         */
        bool is_request;

        /**
         * Message contains encrypted content.
         */
        bool encrypted_content;
        
        /**
         * Number of payload rules which will follow
         */
        size_t payload_rule_count;
         
        /**
         * Pointer to first payload rule
         */
        payload_rule_t *payload_rules;
};

/**
 * Message rule for IKE_SA_INIT from initiator.
 */
static payload_rule_t ike_sa_init_i_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,FALSE,FALSE},
        {SECURITY_ASSOCIATION,1,1,FALSE,FALSE},
        {KEY_EXCHANGE,1,1,FALSE,FALSE},
        {NONCE,1,1,FALSE,FALSE},
};

/**
 * Message rule for IKE_SA_INIT from responder.
 */
static payload_rule_t ike_sa_init_r_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,FALSE,TRUE},
        {SECURITY_ASSOCIATION,1,1,FALSE,FALSE},
        {KEY_EXCHANGE,1,1,FALSE,FALSE},
        {NONCE,1,1,FALSE,FALSE},
};

/**
 * Message rule for IKE_AUTH from initiator.
 */
static payload_rule_t ike_auth_i_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,FALSE},
        {ID_INITIATOR,1,1,TRUE,FALSE},
        {CERTIFICATE,0,1,TRUE,FALSE},
        {CERTIFICATE_REQUEST,0,1,TRUE,FALSE},
        {ID_RESPONDER,0,1,TRUE,FALSE},
        {AUTHENTICATION,1,1,TRUE,FALSE},
        {SECURITY_ASSOCIATION,1,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_INITIATOR,1,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_RESPONDER,1,1,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
};

/**
 * Message rule for IKE_AUTH from responder.
 */
static payload_rule_t ike_auth_r_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,TRUE},
        {CERTIFICATE,0,1,TRUE,FALSE},
        {ID_RESPONDER,1,1,TRUE,FALSE},
        {AUTHENTICATION,1,1,TRUE,FALSE},
        {SECURITY_ASSOCIATION,1,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_INITIATOR,1,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_RESPONDER,1,1,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
};


/**
 * Message rule for INFORMATIONAL from initiator.
 */
static payload_rule_t informational_i_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
        {DELETE,0,1,TRUE,FALSE},
        
};

/**
 * Message rule for INFORMATIONAL from responder.
 */
static payload_rule_t informational_r_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
        {DELETE,0,1,TRUE,FALSE},
};

/**
 * Message rule for CREATE_CHILD_SA from initiator.
 */
static payload_rule_t create_child_sa_i_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,FALSE},
        {SECURITY_ASSOCIATION,1,1,TRUE,FALSE},
        {NONCE,1,1,TRUE,FALSE},
        {KEY_EXCHANGE,0,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_INITIATOR,0,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_RESPONDER,0,1,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
};

/**
 * Message rule for CREATE_CHILD_SA from responder.
 */
static payload_rule_t create_child_sa_r_payload_rules[] = {
        {NOTIFY,0,MAX_NOTIFY_PAYLOADS,TRUE,TRUE},
        {SECURITY_ASSOCIATION,1,1,TRUE,FALSE},
        {NONCE,1,1,TRUE,FALSE},
        {KEY_EXCHANGE,0,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_INITIATOR,0,1,TRUE,FALSE},
        {TRAFFIC_SELECTOR_RESPONDER,0,1,TRUE,FALSE},
        {CONFIGURATION,0,1,TRUE,FALSE},
};


/**
 * Message rules, defines allowed payloads.
 */
static message_rule_t message_rules[] = {
        {IKE_SA_INIT,TRUE,FALSE,(sizeof(ike_sa_init_i_payload_rules)/sizeof(payload_rule_t)),ike_sa_init_i_payload_rules},
        {IKE_SA_INIT,FALSE,FALSE,(sizeof(ike_sa_init_r_payload_rules)/sizeof(payload_rule_t)),ike_sa_init_r_payload_rules},
        {IKE_AUTH,TRUE,TRUE,(sizeof(ike_auth_i_payload_rules)/sizeof(payload_rule_t)),ike_auth_i_payload_rules},
        {IKE_AUTH,FALSE,TRUE,(sizeof(ike_auth_r_payload_rules)/sizeof(payload_rule_t)),ike_auth_r_payload_rules},
        {INFORMATIONAL,TRUE,TRUE,(sizeof(informational_i_payload_rules)/sizeof(payload_rule_t)),informational_i_payload_rules},
        {INFORMATIONAL,FALSE,TRUE,(sizeof(informational_r_payload_rules)/sizeof(payload_rule_t)),informational_r_payload_rules},
        {CREATE_CHILD_SA,TRUE,TRUE,(sizeof(create_child_sa_i_payload_rules)/sizeof(payload_rule_t)),create_child_sa_i_payload_rules},
        {CREATE_CHILD_SA,FALSE,TRUE,(sizeof(create_child_sa_r_payload_rules)/sizeof(payload_rule_t)),create_child_sa_r_payload_rules},
};


typedef struct private_message_t private_message_t;

/**
 * Private data of an message_t object.
 */
struct private_message_t {

        /**
         * Public part of a message_t object.
         */
        message_t public;

        /**
         * Minor version of message.
         */
        u_int8_t major_version;
        
        /**
         * Major version of message.
         */
        u_int8_t minor_version;
        
        /**
         * First Payload in message.
         */
        payload_type_t first_payload;

        /**
         * Assigned exchange type.
         */
        exchange_type_t exchange_type;

        /**
         * TRUE if message is a request, FALSE if a reply.
         */
        bool is_request;
        
        /**
         * Message ID of this message.
         */
        u_int32_t message_id;
        
        /**
         * ID of assigned IKE_SA.
         */
        ike_sa_id_t *ike_sa_id;
        
        /**
         * Assigned UDP packet, stores incoming packet or last generated one.
         */
        packet_t *packet;
         
        /**
         * Linked List where payload data are stored in.
         */
        linked_list_t *payloads;
        
         /**
          * Assigned parser to parse Header and Body of this message.
          */
        parser_t *parser;
        
        /**
         * The message rule for this message instance
         */
        message_rule_t *message_rule;
};

/**
 * Implementation of private_message_t.set_message_rule.
 */
static  status_t set_message_rule(private_message_t *this)
{
        int i;
                
        for (i = 0; i < (sizeof(message_rules) / sizeof(message_rule_t)); i++)
        {
                if ((this->exchange_type == message_rules[i].exchange_type) &&
                        (this->is_request == message_rules[i].is_request))
                {
                        /* found rule for given exchange_type*/
                        this->message_rule = &(message_rules[i]);
                        return SUCCESS;
                }
        }
        this->message_rule = NULL;
        return NOT_FOUND;
}

/**
 * Implementation of private_message_t.get_payload_rule.
 */
static status_t get_payload_rule(private_message_t *this, payload_type_t payload_type, payload_rule_t **payload_rule)
{
        int i;
        
        for (i = 0; i < this->message_rule->payload_rule_count;i++)
        {
                if (this->message_rule->payload_rules[i].payload_type == payload_type)
                {
                        *payload_rule = &(this->message_rule->payload_rules[i]);
                        return SUCCESS;
                }
        }
        
        *payload_rule = NULL;
        return NOT_FOUND;
}

/**
 * Implementation of message_t.set_ike_sa_id.
 */
static void set_ike_sa_id (private_message_t *this,ike_sa_id_t *ike_sa_id)
{
        this->ike_sa_id = ike_sa_id->clone(ike_sa_id);
}

/**
 * Implementation of message_t.get_ike_sa_id.
 */
static ike_sa_id_t* get_ike_sa_id (private_message_t *this)
{
        return this->ike_sa_id;
}

/**
 * Implementation of message_t.set_message_id.
 */
static void set_message_id (private_message_t *this,u_int32_t message_id)
{
        this->message_id = message_id;
}

/**
 * Implementation of message_t.get_message_id.
 */
static u_int32_t get_message_id (private_message_t *this)
{
        return this->message_id;
}

/**
 * Implementation of message_t.get_initiator_spi.
 */
static u_int64_t get_initiator_spi (private_message_t *this)
{
        return (this->ike_sa_id->get_initiator_spi(this->ike_sa_id));
}

/**
 * Implementation of message_t.get_responder_spi.
 */
static u_int64_t get_responder_spi (private_message_t *this)
{
        return (this->ike_sa_id->get_responder_spi(this->ike_sa_id));
}

/**
 * Implementation of message_t.set_major_version.
 */
static void set_major_version (private_message_t *this,u_int8_t major_version)
{
        this->major_version = major_version;
}


/**
 * Implementation of message_t.set_major_version.
 */
static u_int8_t get_major_version (private_message_t *this)
{
        return this->major_version;
}

/**
 * Implementation of message_t.set_minor_version.
 */
static void set_minor_version (private_message_t *this,u_int8_t minor_version)
{
        this->minor_version = minor_version;
}

/**
 * Implementation of message_t.get_minor_version.
 */
static u_int8_t get_minor_version (private_message_t *this)
{
        return this->minor_version;
}

/**
 * Implementation of message_t.set_exchange_type.
 */
static void set_exchange_type (private_message_t *this,exchange_type_t exchange_type)
{
        this->exchange_type = exchange_type;
}

/**
 * Implementation of message_t.get_exchange_type.
 */
static exchange_type_t get_exchange_type (private_message_t *this)
{
        return this->exchange_type;
}

/**
 * Implementation of message_t.set_request.
 */
static void set_request (private_message_t *this,bool request)
{
        this->is_request = request;
}

/**
 * Implementation of message_t.get_request.
 */
static exchange_type_t get_request (private_message_t *this)
{
        return this->is_request;
}

/**
 * Is this message in an encoded form?
 */
static bool is_encoded(private_message_t *this)
{
        chunk_t data = this->packet->get_data(this->packet);
        
        if (data.ptr == NULL)
        {
                return FALSE;
        }
        return TRUE;
}

/**
 * Implementation of message_t.add_payload.
 */
static void add_payload(private_message_t *this, payload_t *payload)
{
        payload_t *last_payload;
        if (this->payloads->get_count(this->payloads) > 0)
        {
                this->payloads->get_last(this->payloads,(void **) &last_payload);
                last_payload->set_next_type(last_payload, payload->get_type(payload));
        }
        else
        {
                this->first_payload = payload->get_type(payload);
        }
        payload->set_next_type(payload, NO_PAYLOAD);
        this->payloads->insert_last(this->payloads, (void*)payload);

        DBG2(SIG_DBG_ENC ,"added payload of type %N to message",
                 payload_type_names, payload->get_type(payload));
}

/**
 * Implementation of message_t.set_source.
 */
static void set_source(private_message_t *this, host_t *host)
{
        this->packet->set_source(this->packet, host);
}

/**
 * Implementation of message_t.set_destination.
 */
static void set_destination(private_message_t *this, host_t *host)
{
        this->packet->set_destination(this->packet, host);
}

/**
 * Implementation of message_t.get_source.
 */
static host_t* get_source(private_message_t *this)
{
        return this->packet->get_source(this->packet);
}

/**
 * Implementation of message_t.get_destination.
 */
static host_t * get_destination(private_message_t *this)
{
        return this->packet->get_destination(this->packet);
}

/**
 * Implementation of message_t.get_destination.
 */
static iterator_t *get_payload_iterator(private_message_t *this)
{
        return this->payloads->create_iterator(this->payloads, TRUE);
}

/**
 * output handler in printf()
 */
static int print(FILE *stream, const struct printf_info *info,
                                 const void *const *args)
{
        private_message_t *this = *((private_message_t**)(args[0]));
        iterator_t *iterator;
        payload_t *payload;
        bool first = TRUE;
        size_t total_written = 0;
        size_t written;
        
        if (this == NULL)
        {
                return fprintf(stream, "(null)");
        }
        
        written = fprintf(stream, "%N %s [", 
                                          exchange_type_names, this->exchange_type,
                                          this->is_request ? "request" : "response");
        if (written < 0)
        {
                return written;
        }
        total_written += written;
        
        iterator = this->payloads->create_iterator(this->payloads, TRUE);
        while (iterator->iterate(iterator, (void**)&payload))
        {
                if (!first)
                {
                        written = fprintf(stream, " ");
                        if (written < 0)
                        {
                                return written;
                        }
                        total_written += written;
                }
                else
                {
                        first = FALSE;
                }
                written = fprintf(stream, "%N", payload_type_short_names,
                                                  payload->get_type(payload));
                if (written < 0)
                {
                        return written;
                }
                total_written += written;
        }
        iterator->destroy(iterator);
        written = fprintf(stream, "]");
        if (written < 0)
        {
                return written;
        }
        total_written += written;
        return total_written;
}

/**
 * arginfo handler in printf()
 */
static int print_arginfo(const struct printf_info *info, size_t n, int *argtypes)
{
        if (n > 0)
        {
                argtypes[0] = PA_POINTER;
        }
        return 1;
}

/**
 * register printf() handlers
 */
static void __attribute__ ((constructor))print_register()
{
        register_printf_function(MESSAGE_PRINTF_SPEC, print, print_arginfo);
}

/**
 * Implementation of private_message_t.encrypt_payloads.
 */
static status_t encrypt_payloads (private_message_t *this,crypter_t *crypter, signer_t* signer)
{
        encryption_payload_t *encryption_payload = NULL;
        status_t status;
        linked_list_t *all_payloads;
        
        if (!this->message_rule->encrypted_content)
        {
                DBG2(SIG_DBG_ENC, "message doesn't have to be encrypted");
                /* message contains no content to encrypt */
                return SUCCESS;
        }
        
        DBG2(SIG_DBG_ENC, "copy all payloads to a temporary list");
        all_payloads = linked_list_create();
        
        /* first copy all payloads in a temporary list */
        while (this->payloads->get_count(this->payloads) > 0)
        {
                void *current_payload;
                this->payloads->remove_first(this->payloads,&current_payload);
                all_payloads->insert_last(all_payloads,current_payload);
        }
        
        encryption_payload = encryption_payload_create();

        DBG2(SIG_DBG_ENC, "check each payloads if they have to get encrypted");
        while (all_payloads->get_count(all_payloads) > 0)
        {
                payload_rule_t *payload_rule;
                payload_t *current_payload;
                bool to_encrypt = FALSE;
                
                all_payloads->remove_first(all_payloads,(void **)&current_payload);
                
                status = get_payload_rule(this,
                                        current_payload->get_type(current_payload),&payload_rule);
                /* for payload types which are not found in supported payload list, 
                 * it is presumed that they don't have to be encrypted */
                if ((status == SUCCESS) && (payload_rule->encrypted))
                {
                        DBG2(SIG_DBG_ENC, "payload %N gets encrypted",
                                 payload_type_names, current_payload->get_type(current_payload));
                        to_encrypt = TRUE;
                }
                
                if (to_encrypt)
                {
                        DBG2(SIG_DBG_ENC, "insert payload %N to encryption payload",
                                 payload_type_names, current_payload->get_type(current_payload));
                        encryption_payload->add_payload(encryption_payload,current_payload);
                }
                else
                {
                        DBG2(SIG_DBG_ENC, "insert payload %N unencrypted",
                                 payload_type_names ,current_payload->get_type(current_payload));
                        add_payload(this, (payload_t*)encryption_payload);
                }
        }

        status = SUCCESS;
        DBG2(SIG_DBG_ENC, "encrypting encryption payload");
        encryption_payload->set_transforms(encryption_payload, crypter,signer);
        status = encryption_payload->encrypt(encryption_payload);
        DBG2(SIG_DBG_ENC, "add encrypted payload to payload list");
        add_payload(this, (payload_t*)encryption_payload);
        
        all_payloads->destroy(all_payloads);
        
        return status;
}

/**
 * Implementation of message_t.generate.
 */
static status_t generate(private_message_t *this, crypter_t *crypter, signer_t* signer, packet_t **packet)
{
        generator_t *generator;
        ike_header_t *ike_header;
        payload_t *payload, *next_payload;
        iterator_t *iterator;
        status_t status;
        chunk_t packet_data;
        
        if (is_encoded(this))
        {
                /* already generated, return a new packet clone */
                *packet = this->packet->clone(this->packet);
                return SUCCESS;
        }
        
        DBG1(SIG_DBG_ENC, "generating %M", this);
        
        if (this->exchange_type == EXCHANGE_TYPE_UNDEFINED)
        {
                DBG1(SIG_DBG_ENC, "exchange type is not defined");
                return INVALID_STATE;
        }
        
        if (this->packet->get_source(this->packet) == NULL ||
                this->packet->get_destination(this->packet) == NULL) 
        {
                DBG1(SIG_DBG_ENC, "%s not defined",
                         !this->packet->get_source(this->packet) ? "source" : "destination");
                return INVALID_STATE;
        }
        
        /* set the rules for this messge */
        status = set_message_rule(this);
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "no message rules specified for this message type");
                return NOT_SUPPORTED;
        }
        
        /* going to encrypt all content which have to be encrypted */
        status = encrypt_payloads(this, crypter, signer);
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "payload encryption failed");
                return status;
        }
        
        /* build ike header */
        ike_header = ike_header_create();
        
        ike_header->set_exchange_type(ike_header, this->exchange_type);
        ike_header->set_message_id(ike_header, this->message_id);
        ike_header->set_response_flag(ike_header, !this->is_request);
        ike_header->set_initiator_flag(ike_header, this->ike_sa_id->is_initiator(this->ike_sa_id));
        ike_header->set_initiator_spi(ike_header, this->ike_sa_id->get_initiator_spi(this->ike_sa_id));
        ike_header->set_responder_spi(ike_header, this->ike_sa_id->get_responder_spi(this->ike_sa_id));

        generator = generator_create();
        
        payload = (payload_t*)ike_header;

        
        /* generate every payload expect last one, this is doen later*/
        iterator = this->payloads->create_iterator(this->payloads, TRUE);
        while(iterator->iterate(iterator, (void**)&next_payload))
        {
                payload->set_next_type(payload, next_payload->get_type(next_payload));
                generator->generate_payload(generator, payload);
                payload = next_payload;
        }
        iterator->destroy(iterator);
        
        /* last payload has no next payload*/
        payload->set_next_type(payload, NO_PAYLOAD);

        generator->generate_payload(generator, payload);

        ike_header->destroy(ike_header);
                
        /* build packet */
        generator->write_to_chunk(generator, &packet_data);
        generator->destroy(generator);
        
        /* if last payload is of type encrypted, integrity checksum if necessary */
        if (payload->get_type(payload) == ENCRYPTED)
        {
                DBG2(SIG_DBG_ENC, "build signature on whole message");
                encryption_payload_t *encryption_payload = (encryption_payload_t*)payload;
                status = encryption_payload->build_signature(encryption_payload, packet_data);
                if (status != SUCCESS)
                {
                        return status;
                }
        }
        
        this->packet->set_data(this->packet, packet_data);
        
        /* clone packet for caller */
        *packet = this->packet->clone(this->packet);
        
        DBG2(SIG_DBG_ENC, "message generated successfully");
        return SUCCESS;
}

/**
 * Implementation of message_t.get_packet.
 */
static packet_t *get_packet (private_message_t *this)
{
        return this->packet->clone(this->packet);
}

/**
 * Implementation of message_t.get_packet_data.
 */
static chunk_t get_packet_data (private_message_t *this)
{
        return chunk_clone(this->packet->get_data(this->packet));
}

/**
 * Implementation of message_t.parse_header.
 */
static status_t parse_header(private_message_t *this)
{
        ike_header_t *ike_header;
        status_t status;
        
        DBG2(SIG_DBG_ENC, "parsing header of message");
        
        this->parser->reset_context(this->parser);
        status = this->parser->parse_payload(this->parser,HEADER,(payload_t **) &ike_header);
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "header could not be parsed");
                return status;
                
        }
        
        /* verify payload */
        status = ike_header->payload_interface.verify(&(ike_header->payload_interface));
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "header verification failed");
                ike_header->destroy(ike_header);
                return status;
        }
        
        if (this->ike_sa_id != NULL)
        {
                this->ike_sa_id->destroy(this->ike_sa_id);
        }
        
        this->ike_sa_id = ike_sa_id_create(ike_header->get_initiator_spi(ike_header),
                                                                           ike_header->get_responder_spi(ike_header),
                                                                           ike_header->get_initiator_flag(ike_header));

        this->exchange_type = ike_header->get_exchange_type(ike_header);
        this->message_id = ike_header->get_message_id(ike_header);
        this->is_request = (!(ike_header->get_response_flag(ike_header)));
        this->major_version = ike_header->get_maj_version(ike_header);
        this->minor_version = ike_header->get_min_version(ike_header);
        this->first_payload = ike_header->payload_interface.get_next_type(&(ike_header->payload_interface));
        
        DBG2(SIG_DBG_ENC, "parsed a %N %s", exchange_type_names, this->exchange_type,
                 this->is_request ? "request" : "response");
        
        ike_header->destroy(ike_header);
        
        /* get the rules for this messge */
        status = set_message_rule(this);
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "no message rules specified for a %N %s",
                         exchange_type_names, this->exchange_type,
                         this->is_request ? "request" : "response");
        }
        
        return status;
}

/**
 * Implementation of private_message_t.decrypt_and_verify_payloads.
 */
static status_t decrypt_payloads(private_message_t *this,crypter_t *crypter, signer_t* signer)
{
        bool current_payload_was_encrypted = FALSE;
        payload_t *previous_payload = NULL;
        int payload_number = 1;
        iterator_t *iterator;
        payload_t *current_payload;
        status_t status;

        iterator = this->payloads->create_iterator(this->payloads,TRUE);

        /* process each payload and decrypt a encryption payload */
        while(iterator->iterate(iterator, (void**)&current_payload))
        {
                payload_rule_t *payload_rule;
                payload_type_t current_payload_type;
                
                /* needed to check */
                current_payload_type = current_payload->get_type(current_payload);
                
                DBG2(SIG_DBG_ENC, "process payload of type %N",
                         payload_type_names, current_payload_type);
                
                if (current_payload_type == ENCRYPTED)
                {
                        encryption_payload_t *encryption_payload;
                        payload_t *current_encrypted_payload;
                        
                        encryption_payload = (encryption_payload_t*)current_payload;
                        
                        DBG2(SIG_DBG_ENC, "found an encryption payload");

                        if (payload_number != this->payloads->get_count(this->payloads))
                        {
                                /* encrypted payload is not last one */
                                DBG1(SIG_DBG_ENC, "encrypted payload is not last payload");
                                iterator->destroy(iterator);
                                return VERIFY_ERROR;
                        }
                        /* decrypt */
                        encryption_payload->set_transforms(encryption_payload, crypter, signer);
                        DBG2(SIG_DBG_ENC, "verify signature of encryption payload");
                        status = encryption_payload->verify_signature(encryption_payload,
                                                                                this->packet->get_data(this->packet));
                        if (status != SUCCESS)
                        {
                                DBG1(SIG_DBG_ENC, "encryption payload signature invalid");
                                iterator->destroy(iterator);
                                return FAILED;
                        }
                        DBG2(SIG_DBG_ENC, "decrypting content of encryption payload");
                        status = encryption_payload->decrypt(encryption_payload);
                        if (status != SUCCESS)
                        {
                                DBG1(SIG_DBG_ENC, "encrypted payload could not be decrypted and parsed");
                                iterator->destroy(iterator);
                                return PARSE_ERROR;
                        }
                        
                        /* needed later to find out if a payload was encrypted */
                        current_payload_was_encrypted = TRUE;
                        
                        /* check if there are payloads contained in the encryption payload */
                        if (encryption_payload->get_payload_count(encryption_payload) == 0)
                        {
                                DBG2(SIG_DBG_ENC, "encrypted payload is empty");
                                /* remove the encryption payload, is not needed anymore */
                                iterator->remove(iterator);
                                /* encrypted payload contains no other payload */
                                current_payload_type = NO_PAYLOAD;
                        }
                        else
                        {
                                /* encryption_payload is replaced with first payload contained in encryption_payload */
                                encryption_payload->remove_first_payload(encryption_payload, &current_encrypted_payload);
                                iterator->replace(iterator,NULL,(void *) current_encrypted_payload);
                                current_payload_type = current_encrypted_payload->get_type(current_encrypted_payload);
                        }
                        
                        /* is the current paylad the first in the message? */
                        if (previous_payload == NULL)
                        {
                                /* yes, set the first payload type of the message to the current type */
                                this->first_payload = current_payload_type;
                        }
                        else
                        {
                                /* no, set the next_type of the previous payload to the current type */
                                previous_payload->set_next_type(previous_payload, current_payload_type);
                        }
                        
                        /* all encrypted payloads are added to the payload list */
                        while (encryption_payload->get_payload_count(encryption_payload) > 0)
                        {
                                encryption_payload->remove_first_payload(encryption_payload, &current_encrypted_payload);
                                DBG2(SIG_DBG_ENC, "insert unencrypted payload of type %N at end of list",
                                         payload_type_names, current_encrypted_payload->get_type(current_encrypted_payload));
                                this->payloads->insert_last(this->payloads,current_encrypted_payload);
                        }
                        
                        /* encryption payload is processed, payloads are moved. Destroy it. */
                        encryption_payload->destroy(encryption_payload);        
                }

                /* we allow unknown payloads of any type and don't bother if it was encrypted. Not our problem. */
                if (current_payload_type != UNKNOWN_PAYLOAD && current_payload_type != NO_PAYLOAD)
                {
                        /* get the ruleset for found payload */
                        status = get_payload_rule(this, current_payload_type, &payload_rule);
                        if (status != SUCCESS)
                        {
                                /* payload is not allowed */
                                DBG1(SIG_DBG_ENC, "payload type %N not allowed",
                                                                  payload_type_names, current_payload_type);
                                iterator->destroy(iterator);
                                return VERIFY_ERROR;
                        }
                        
                        /* check if the payload was encrypted, and if it should been have encrypted */
                        if (payload_rule->encrypted != current_payload_was_encrypted)
                        {
                                /* payload was not encrypted, but should have been. or vice-versa */
                                DBG1(SIG_DBG_ENC, "payload type %N should be %s!",
                                         payload_type_names, current_payload_type,
                                         (payload_rule->encrypted) ? "encrypted" : "not encrypted");
                                iterator->destroy(iterator);
                                return VERIFY_ERROR;
                        }
                }
                /* advance to the next payload */
                payload_number++;
                /* is stored to set next payload in case of found encryption payload */
                previous_payload = current_payload;
        }
        iterator->destroy(iterator);
        return SUCCESS;
}

/**
 * Implementation of private_message_t.verify.
 */
static status_t verify(private_message_t *this)
{
        int i;
        iterator_t *iterator;
        payload_t *current_payload;
        size_t total_found_payloads = 0;
        
        DBG2(SIG_DBG_ENC, "verifying message structure");
        
        iterator = this->payloads->create_iterator(this->payloads,TRUE);
        /* check for payloads with wrong count*/
        for (i = 0; i < this->message_rule->payload_rule_count;i++)
        {
                size_t found_payloads = 0;
        
                /* check all payloads for specific rule */
                iterator->reset(iterator);
                
                while(iterator->iterate(iterator,(void **)&current_payload))
                {
                        payload_type_t current_payload_type;
                        
                        current_payload_type = current_payload->get_type(current_payload);
                        if (current_payload_type == UNKNOWN_PAYLOAD)
                        {
                                /* unknown payloads are ignored, IF they are not critical */
                                unknown_payload_t *unknown_payload = (unknown_payload_t*)current_payload;
                                if (unknown_payload->is_critical(unknown_payload))
                                {
                                        DBG1(SIG_DBG_ENC, "%N is not supported, but its critical!",
                                                 payload_type_names, current_payload_type);
                                        iterator->destroy(iterator);
                                        return NOT_SUPPORTED;   
                                }
                        }
                        else if (current_payload_type == this->message_rule->payload_rules[i].payload_type)
                        {
                                found_payloads++;
                                total_found_payloads++;
                                DBG2(SIG_DBG_ENC, "found payload of type %N",
                                         payload_type_names, this->message_rule->payload_rules[i].payload_type);
                                
                                /* as soon as ohe payload occures more then specified, the verification fails */
                                if (found_payloads > this->message_rule->payload_rules[i].max_occurence)
                                {
                                        DBG1(SIG_DBG_ENC, "payload of type %N more than %d times (%d) occured in current message",
                                                 payload_type_names, current_payload_type,
                                                 this->message_rule->payload_rules[i].max_occurence, found_payloads);
                                        iterator->destroy(iterator);
                                        return VERIFY_ERROR;
                                }
                        }
                }
                
                if (found_payloads < this->message_rule->payload_rules[i].min_occurence)
                {
                        DBG1(SIG_DBG_ENC, "payload of type %N not occured %d times (%d)",
                                 payload_type_names, this->message_rule->payload_rules[i].payload_type,
                                 this->message_rule->payload_rules[i].min_occurence, found_payloads);
                        iterator->destroy(iterator);
                        return VERIFY_ERROR;
                }
                if ((this->message_rule->payload_rules[i].sufficient) && (this->payloads->get_count(this->payloads) == total_found_payloads))
                {
                        iterator->destroy(iterator);
                        return SUCCESS; 
                }
        }
        iterator->destroy(iterator);
        return SUCCESS;
}

/**
 * Implementation of message_t.parse_body.
 */
static status_t parse_body(private_message_t *this, crypter_t *crypter, signer_t *signer)
{
        status_t status = SUCCESS;
        payload_type_t current_payload_type;
                
        current_payload_type = this->first_payload;     
                
        DBG2(SIG_DBG_ENC, "parsing body of message, first payload is %N",
                 payload_type_names, current_payload_type);

        /* parse payload for payload, while there are more available */
        while ((current_payload_type != NO_PAYLOAD))
        {
                payload_t *current_payload;
                
                DBG2(SIG_DBG_ENC, "starting parsing a %N payload", 
                         payload_type_names, current_payload_type);
                
                /* parse current payload */
                status = this->parser->parse_payload(this->parser,current_payload_type,(payload_t **) &current_payload);
                
                if (status != SUCCESS)
                {
                        DBG1(SIG_DBG_ENC, "payload type %N could not be parsed",
                                 payload_type_names, current_payload_type);
                        return PARSE_ERROR;
                }

                DBG2(SIG_DBG_ENC, "verifying payload of type %N",
                         payload_type_names, current_payload_type);
                
                /* verify it, stop parsig if its invalid */
                status = current_payload->verify(current_payload);
                if (status != SUCCESS)
                {
                        DBG1(SIG_DBG_ENC, "%N payload verification failed",
                                 payload_type_names, current_payload_type);
                        current_payload->destroy(current_payload);
                        return VERIFY_ERROR;
                }
                
                DBG2(SIG_DBG_ENC, "%N payload verified. Adding to payload list",
                         payload_type_names, current_payload_type);
                this->payloads->insert_last(this->payloads,current_payload);
                
                /* an encryption payload is the last one, so STOP here. decryption is done later */
                if (current_payload_type == ENCRYPTED)
                {
                        DBG2(SIG_DBG_ENC, "%N payload found. Stop parsing",
                                 payload_type_names, current_payload_type);
                        break;
                }
                
                /* get next payload type */
                current_payload_type = current_payload->get_next_type(current_payload);
        }

        if (current_payload_type == ENCRYPTED)
        {
                status = decrypt_payloads(this,crypter,signer);
                if (status != SUCCESS)
                {
                        DBG1(SIG_DBG_ENC, "could not decrypt payloads");
                        return status;
                }
        }
        
        status = verify(this);
        if (status != SUCCESS)
        {
                DBG1(SIG_DBG_ENC, "verification of message failed");
                return status;
        }
        
        DBG1(SIG_DBG_ENC, "parsed %M", this);
        
        return SUCCESS;
}

/**
 * Implementation of message_t.destroy.
 */
static void destroy (private_message_t *this)
{
        DESTROY_IF(this->ike_sa_id);
        this->payloads->destroy_offset(this->payloads, offsetof(payload_t, destroy));
        this->packet->destroy(this->packet);
        this->parser->destroy(this->parser);
        free(this);
}

/*
 * Described in Header-File
 */
message_t *message_create_from_packet(packet_t *packet)
{
        private_message_t *this = malloc_thing(private_message_t);

        /* public functions */
        this->public.set_major_version = (void(*)(message_t*, u_int8_t))set_major_version;
        this->public.get_major_version = (u_int8_t(*)(message_t*))get_major_version;
        this->public.set_minor_version = (void(*)(message_t*, u_int8_t))set_minor_version;
        this->public.get_minor_version = (u_int8_t(*)(message_t*))get_minor_version;
        this->public.set_message_id = (void(*)(message_t*, u_int32_t))set_message_id;
        this->public.get_message_id = (u_int32_t(*)(message_t*))get_message_id;
        this->public.get_initiator_spi = (u_int64_t(*)(message_t*))get_initiator_spi;
        this->public.get_responder_spi = (u_int64_t(*)(message_t*))get_responder_spi;
        this->public.set_ike_sa_id = (void(*)(message_t*, ike_sa_id_t *))set_ike_sa_id;
        this->public.get_ike_sa_id = (ike_sa_id_t*(*)(message_t*))get_ike_sa_id;
        this->public.set_exchange_type = (void(*)(message_t*, exchange_type_t))set_exchange_type;
        this->public.get_exchange_type = (exchange_type_t(*)(message_t*))get_exchange_type;
        this->public.set_request = (void(*)(message_t*, bool))set_request;
        this->public.get_request = (bool(*)(message_t*))get_request;
        this->public.add_payload = (void(*)(message_t*,payload_t*))add_payload;
        this->public.generate = (status_t (*) (message_t *,crypter_t*,signer_t*,packet_t**)) generate;
        this->public.set_source = (void (*) (message_t*,host_t*)) set_source;
        this->public.get_source = (host_t * (*) (message_t*)) get_source;
        this->public.set_destination = (void (*) (message_t*,host_t*)) set_destination;
        this->public.get_destination = (host_t * (*) (message_t*)) get_destination;
        this->public.get_payload_iterator = (iterator_t * (*) (message_t *)) get_payload_iterator;
        this->public.parse_header = (status_t (*) (message_t *)) parse_header;
        this->public.parse_body = (status_t (*) (message_t *,crypter_t*,signer_t*)) parse_body;
        this->public.get_packet = (packet_t * (*) (message_t*)) get_packet;
        this->public.get_packet_data = (chunk_t (*) (message_t *this)) get_packet_data;
        this->public.destroy = (void(*)(message_t*))destroy;
                
        /* private values */
        this->exchange_type = EXCHANGE_TYPE_UNDEFINED;
        this->is_request = TRUE;
        this->ike_sa_id = NULL;
        this->first_payload = NO_PAYLOAD;
        this->message_id = 0;
        
        /* private values */
        if (packet == NULL)
        {
                packet = packet_create();       
        }
        this->message_rule = NULL;
        this->packet = packet;
        this->payloads = linked_list_create();
        
        /* parser is created from data of packet */
        this->parser = parser_create(this->packet->get_data(this->packet));
        
        return (&this->public);
}

/*
 * Described in Header.
 */
message_t *message_create()
{
        return message_create_from_packet(NULL);
}