rohc_comp_internals.h

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/*
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * @file    rohc_comp_internals.h
 * @brief   Internal structures for ROHC compression
 * @author  Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author  Didier Barvaux <didier@barvaux.org>
 * @author  The hackers from ROHC for Linux
 */

#ifndef ROHC_COMP_INTERNALS_H
#define ROHC_COMP_INTERNALS_H

#include "rohc.h" /* for struct medium */
#include "rohc_packets.h"
#include "rohc_comp.h"
#include "wlsb.h"
#include "ip.h"

#include <stdbool.h>


/*
 * Constants and macros
 */

/** The number of ROHC profiles ready to be used */
#define C_NUM_PROFILES 6

/** The maximal number of outgoing feedbacks that can be queued */
#define FEEDBACK_RING_SIZE 10


/*
 * Declare ROHC compression structures that are defined at the end of this
 * file but used by other structures at the beginning of the file.
 */

struct c_feedback;
struct c_context;


/*
 * Definitions of ROHC compression structures
 */


/**
 * @brief Information on ROHC feedback data
 */
struct rohc_feedback
{
        /** The feedback data */
        unsigned char *data;
        /** The length (in bytes) of the feedback data */
        size_t length;
        /** Whether the feedback data was locked during packet build? */
        bool is_locked;
};


/**
 * @brief The ROHC compressor
 */
struct rohc_comp
{
        /**
         * @brief Whether the compressor is enabled or not
         *
         * The compressor is enabled by default and may be disabled by user.
         */
        int enabled;

        /** The medium associated with the decompressor */
        struct medium medium;

        /** The array of compression contexts that use the compressor */
        struct c_context *contexts;
        /** The number of compression contexts stored in the array */
        int num_contexts;
        /** The number of compression contexts in use in the array */
        int num_contexts_used;

        /**
         * @brief Which profiles are enabled and with one are not?
         *
         * A value of 1 means that profile is enabled, 0 means disabled.
         */
        int profiles[C_NUM_PROFILES];


        /* CRC-related variables: */

        /** The table to enable fast CRC-2 computation */
        unsigned char crc_table_2[256];
        /** The table to enable fast CRC-3 computation */
        unsigned char crc_table_3[256];
        /** The table to enable fast CRC-6 computation */
        unsigned char crc_table_6[256];
        /** The table to enable fast CRC-7 computation */
        unsigned char crc_table_7[256];
        /** The table to enable fast CRC-8 computation */
        unsigned char crc_table_8[256];


        /* feedback-related variables: */

        /** The ring of outgoing feedbacks */
        struct rohc_feedback feedbacks[FEEDBACK_RING_SIZE];
        /** The index of the oldest feedback in the feedback ring */
        size_t feedbacks_first;
        /** The index of the oldest unlocked feedback in the feedback ring */
        size_t feedbacks_first_unlocked;
        /** @brief The index of the next empty location in the feedback ring */
        size_t feedbacks_next;


        /* some statistics about the compression process: */

        /** The number of sent packets */
        int num_packets;
        /** The size of all the received uncompressed IP packets */
        int total_uncompressed_size;
        /** The size of all the sent compressed ROHC packets */
        int total_compressed_size;

        /** The last context used by the compressor */
        struct c_context *last_context;


        /* random callback */

        /** The user-defined callback for random numbers */
        rohc_comp_random_cb_t random_cb;
        /** Private data that will be given to the callback for random numbers */
        void *random_cb_ctxt;


        /* user interaction variables: */

        /** The width of the W-LSB sliding window */
        size_t wlsb_window_width;
        /** The maximal number of packets sent in > IR states (= FO and SO
         *  states) before changing back the state to IR (periodic refreshes) */
        size_t periodic_refreshes_ir_timeout;
        /** The maximal number of packets sent in > FO states (= SO state)
         *  before changing back the state to FO (periodic refreshes) */
        size_t periodic_refreshes_fo_timeout;
        /** Maximum Reconstructed Reception Unit (currently not used) */
        int mrru;
        /** Maximum header size that will be compressed (currently not used) */
        int max_header_size;
        /** The connection type (currently not used) */
        int connection_type;
};


/**
 * @brief The ROHC compression profile
 *
 * The object defines a ROHC profile. Each field must be filled in
 * for each new profile.
 */
struct c_profile
{
        /**
         * @brief The IP protocol ID used to find out which profile is able to
         *        compress an IP packet
         */
        const unsigned short protocol;

        /**
         * @brief The UDP ports associated with this profile
         *
         * Only used with UDP as transport protocol. The pointer can be NULL if no
         * port is specified. If defined, the list must be terminated by 0.
         * example: { 5000, 5001, 0 }
         */
        const int *ports;

        /** The profile ID as reserved by IANA */
        const unsigned short id;

        /** A string that describes the profile */
        const char *description;

        /**
         * @brief The handler used to create the profile-specific part of the
         *        compression context
         */
        int (*create)(struct c_context *const context,
                      const struct ip_packet *packet);

        /**
         * @brief The handler used to destroy the profile-specific part of the
         *        compression context
         */
        void (*destroy)(struct c_context *const context);

        /**
         * @brief The handler used to check whether an uncompressed IP packet
         *        belongs to a context or not
         */
        int (*check_context)(const struct c_context *context,
                             const struct ip_packet *packet);

        /**
         * @brief The handler used to encode uncompressed IP packets
         */
        int (*encode)(struct c_context *const context,
                      const struct ip_packet *packet,
                      const int packet_size,
                      unsigned char *const dest,
                      const int dest_size,
                      rohc_packet_t *const packet_type,
                      int *const payload_offset);

        /**
         * @brief The handler used to warn the profile-specific part of the
         *        context about the arrival of feedback data
         */
        void (*feedback)(struct c_context *const context,
                         const struct c_feedback *feedback);
};


/**
 * @brief The ROHC compression context
 */
struct c_context
{
        /** Whether the context is in use or not */
        int used;
        /** The time when the context was created */
        unsigned int latest_used;
        /** The time when the context was last used */
        unsigned int first_used;

        /** The context unique ID (CID) */
        int cid;

        /** The associated compressor */
        struct rohc_comp *compressor;

        /** The associated profile */
        const struct c_profile *profile;
        /** Profile-specific data, defined by the profiles */
        void *specific;

        /** The operation mode in which the context operates: U_MODE, O_MODE, R_MODE */
        rohc_mode mode;
        /** The operation state in which the context operates: IR, FO, SO */
        rohc_c_state state;

        /* below are some statistics */

        /* The type of ROHC packet created for the last compressed packet */
        rohc_packet_t packet_type;

        /** The average size of the uncompressed packets */
        int total_uncompressed_size;
        /** The average size of the compressed packets */
        int total_compressed_size;
        /** The average size of the uncompressed headers */
        int header_uncompressed_size;
        /** The average size of the compressed headers */
        int header_compressed_size;

        /** The total size of the last uncompressed packet */
        int total_last_uncompressed_size;
        /** The total size of the last compressed packet */
        int total_last_compressed_size;
        /** The header size of the last uncompressed packet */
        int header_last_uncompressed_size;
        /** The header size of the last compressed packet */
        int header_last_compressed_size;

        /** The number of sent packets */
        int num_sent_packets;
        /** The number of sent IR packets */
        int num_sent_ir;
        /** The number of sent IR-DYN packets */
        int num_sent_ir_dyn;
        /** The number of received feedbacks */
        int num_recv_feedbacks;

        /** The size of the last 16 uncompressed packets */
        struct c_wlsb *total_16_uncompressed;
        /** The size of the last 16 compressed packets */
        struct c_wlsb *total_16_compressed;
        /** The size of the last 16 uncompressed headers */
        struct c_wlsb *header_16_uncompressed;
        /** The size of the last 16 compressed headers */
        struct c_wlsb *header_16_compressed;
};


/**
 * @brief The feedback packet
 */
struct c_feedback
{
        /** The Context ID to which the feedback packet is related */
        int cid;

        /**
         * @brief The type of feedback packet
         *
         * A value of 1 means FEEDBACK-1, value 2 means FEEDBACK-2.
         */
        int type;

        /** The feedback data (ie. the packet excluding the first type octet) */
        unsigned char *data;
        /** The size of the feedback data */
        unsigned char size;

        /**
         * @brief The offset that indicates the beginning of the profile-specific
         *        data in the feedback data
         */
        int specific_offset;
        /** The size of the profile-specific data */
        int specific_size;

        /** The type of acknowledgement (FEEDBACK-2 only) */
        enum
        {
                /** The classical ACKnowledgement */
                ACK,
                /** The Negative ACKnowledgement */
                NACK,
                /** The Negative STATIC ACKnowledgement */
                STATIC_NACK,
                /** Currently unused acknowledgement type */
                RESERVED
        } acktype;
};

#endif