rohc_decomp_internals.h

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/*
 * Copyright 2012,2013,2014 Didier Barvaux
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

/**
 * @file    rohc_decomp_internals.h
 * @brief   Internal structures for ROHC decompression
 * @author  Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author  Didier Barvaux <didier@barvaux.org>
 * @author  David Moreau from TAS
 */

#ifndef ROHC_DECOMP_INTERNALS_H
#define ROHC_DECOMP_INTERNALS_H

#include "rohc_internal.h"
#include "rohc_decomp.h"
#include "rohc_traces_internal.h"
#include "feedback_create.h"
#include "crc.h"


/*
 * Constants and macros
 */


/** The number of ROHC profiles ready to be used */
#define D_NUM_PROFILES 7U


/** Print a warning trace for the given decompression context */
#define rohc_decomp_warn(context, format, ...) \
        rohc_warning((context)->decompressor, ROHC_TRACE_DECOMP, \
                     (context)->profile->id, \
                     format, ##__VA_ARGS__)

/** Print a debug trace for the given decompression context */
#define rohc_decomp_debug(context, format, ...) \
        rohc_debug((context)->decompressor, ROHC_TRACE_DECOMP, \
                   (context)->profile->id, \
                   format, ##__VA_ARGS__)

/** Dump a buffer for the given compression context */
#define rohc_decomp_dump_buf(context, descr, buf, buf_len) \
        do { \
                if(((context)->decompressor->features & ROHC_DECOMP_FEATURE_DUMP_PACKETS) != 0) { \
                        rohc_dump_buf((context)->decompressor->trace_callback, \
                                      (context)->decompressor->trace_callback_priv, \
                                      ROHC_TRACE_DECOMP, ROHC_TRACE_DEBUG, \
                                      descr, buf, buf_len); \
                } \
        } while(0)


/*
 * Definitions of ROHC compression structures
 */


/**
 * @brief Some compressor statistics
 */
struct d_statistics
{
        /* The number of received packets */
        unsigned long received;
        /* The number of bad decompressions due to wrong CRC */
        unsigned long failed_crc;
        /* The number of bad decompressions due to being in the No Context state */
        unsigned long failed_no_context;
        /* The number of bad decompressions */
        unsigned long failed_decomp;

        /** The cumulative size of the compressed packets */
        unsigned long total_compressed_size;
        /** The cumulative size of the uncompressed packets */
        unsigned long total_uncompressed_size;

        /** The cumulative number of successful corrections upon CRC failure */
        unsigned long corrected_crc_failures;
        /** The cumulative number of successful corrections of SN wraparound
         *  upon CRC failure */
        unsigned long corrected_sn_wraparounds;
        /** The cumulative number of successful corrections of incorrect SN updates
         *  upon CRC failure */
        unsigned long corrected_wrong_sn_updates;
};


/**
 * @brief The user configuration for feedback rate-limiting
 *
 * The k and n parameters define a ratio of packets for rate-limiting: an action
 * is performed only for k packets out of the last n packets.
 */
struct rohc_ack_rate_limit
{
        size_t k;          /**< The k rate-limit parameter */
        size_t n;          /**< The n rate-limit parameter */
        size_t threshold;  /**< The computed k/n ratio */
};


/** The user configuration for feedback rate-limiting */
struct rohc_ack_rate_limits
{
        /** The rate-limit parameters to avoid sending feedback too often */
        struct rohc_ack_rate_limit speed;
        /** The rate-limit parameters to avoid sending NACKs too quickly */
        struct rohc_ack_rate_limit nack;
        /** The rate-limit parameters to avoid sending STATIC-NACKs too quickly */
        struct rohc_ack_rate_limit static_nack;
};


/** The statistics collected about the last needed/sent feedbacks */
struct rohc_ack_stats
{
        uint32_t needed;  /**< The needed feedbacks over the last 32 packets */
        uint32_t sent;    /**< The sent feedbacks over the last 32 packets */
};


/**
 * @brief The ROHC decompressor
 */
struct rohc_decomp
{
        /** The medium associated with the decompressor */
        struct rohc_medium medium;

        /** Enabled/disabled features for the decompressor */
        rohc_decomp_features_t features;

        /** Which profiles are enabled and with one are not? */
        bool enabled_profiles[D_NUM_PROFILES];

        /** The operation mode that the contexts shall target */
        rohc_mode_t target_mode;

        /** The array of decompression contexts that use the decompressor */
        struct rohc_decomp_ctxt **contexts;
        /** The number of decompression contexts in use */
        size_t num_contexts_used;
        /** The last decompression context used by the decompressor */
        struct rohc_decomp_ctxt *last_context;


        /* feedback-related variables */

        /** The maximum number of packets sent during one RTT */
        size_t prtt;
        /** The minimum number of SN bits to transmit in feedbacks */
        size_t sn_feedback_min_bits;
        /** The configuration for feedback rate-limiting */
        struct rohc_ack_rate_limits ack_rate_limits;
        /** Whether the last decompressed packets failed or not */
        uint32_t last_pkts_errors;
        /** The informations for feedback rate-limiting */
        struct rohc_ack_stats last_pkt_feedbacks[ROHC_FEEDBACK_RESERVED];


        /* segment-related variables */

/** The maximal value for MRRU */
#define ROHC_MAX_MRRU 65535
        /** The Reconstructed Reception Unit */
        uint8_t rru[ROHC_MAX_MRRU];
        /** The length (in bytes) of the Reconstructed Reception Unit */
        size_t rru_len;
        /** The Maximum Reconstructed Reception Unit (MRRU) */
        size_t mrru;


        /* CRC-related variables: */

        /** The table to enable fast CRC-3 computation */
        uint8_t crc_table_3[256];
        /** The table to enable fast CRC-7 computation */
        uint8_t crc_table_7[256];
        /** The table to enable fast CRC-8 computation */
        uint8_t crc_table_8[256];


        /** Some statistics about the decompression processes */
        struct d_statistics stats;

        /** The callback function used to manage traces */
        rohc_trace_callback2_t trace_callback;
        /** The private context of the callback function used to manage traces */
        void *trace_callback_priv;
};


/**
 * @brief The different correction algorithms available in case of CRC failure
 */
typedef enum
{
        ROHC_DECOMP_CRC_CORR_SN_NONE    = 0, /**< No correction */
        ROHC_DECOMP_CRC_CORR_SN_WRAP    = 1, /**< Correction of SN wraparound */
        ROHC_DECOMP_CRC_CORR_SN_UPDATES = 2, /**< Correction of incorrect SN updates */

} rohc_decomp_crc_corr_t;


/** The context for correction upon CRC failure */
struct rohc_decomp_crc_corr_ctxt
{
        /** The algorithm being used for correction CRC failure */
        rohc_decomp_crc_corr_t algo;
        /** Correction counter (see e and f in 5.3.2.2.4 of the RFC 3095) */
        size_t counter;
/** The number of last packets to record arrival times for */
#define ROHC_MAX_ARRIVAL_TIMES  10U
        /** The arrival times for the last packets */
        struct rohc_ts arrival_times[ROHC_MAX_ARRIVAL_TIMES];
        /** The number of arrival times in arrival_times */
        size_t arrival_times_nr;
        /** The index for the arrival time of the next packet */
        size_t arrival_times_index;
};


/** The information related to the CRC of a ROHC packet */
struct rohc_decomp_crc
{
        rohc_crc_type_t type;  /**< The type of CRC that protects the ROHC header */
        uint8_t bits;          /**< The CRC bits found in ROHC header */
        size_t bits_nr;        /**< The number of CRC bits found in ROHC header */
};


/**
 * @brief The volatile part of the ROHC decompression context
 *
 * The volatile part of the ROHC decompression context lasts only one single
 * packet. Between two ROHC packets, the volatile part of the context is
 * erased.
 */
struct rohc_decomp_volat_ctxt
{
        /** The CRC information extracted from the ROHC packet being parsed */
        struct rohc_decomp_crc crc;

        /** The profile-specific data for bits extracted from the ROHC packet,
         * defined by the profiles */
        void *extr_bits;

        /** The profile-specific data for values decoded from persistent context
         * and bits extracted from the ROHC packet, defined by the profiles */
        void *decoded_values;
};


/**
 * @brief The ROHC decompression context
 */
struct rohc_decomp_ctxt
{
        /** The Context IDentifier (CID) */
        rohc_cid_t cid;

        /** The associated decompressor */
        struct rohc_decomp *decompressor;

        /** The associated profile */
        const struct rohc_decomp_profile *profile;
        /** The persistent profile-specific data, defined by the profiles */
        void *persist_ctxt;
        /** The volatile data, erased between two ROHC packets */
        struct rohc_decomp_volat_ctxt volat_ctxt;

        /** The operation mode in which the context operates */
        rohc_mode_t mode;
        /** The operation state in which the context operates */
        rohc_decomp_state_t state;

        /** Usage timestamp */
        unsigned int latest_used;
        /** Usage timestamp */
        unsigned int first_used;

        /** Whether the last decompressed packets failed or not */
        uint32_t last_pkts_errors;
        /** The informations for feedback rate-limiting */
        struct rohc_ack_stats last_pkt_feedbacks[ROHC_FEEDBACK_RESERVED];

        /** The context for corrections upon CRC failure */
        struct rohc_decomp_crc_corr_ctxt crc_corr;

        /* below are some statistics */

        /** The type of the last decompressed ROHC packet */
        rohc_packet_t packet_type;

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

        /* The number of received packets */
        unsigned long num_recv_packets;
        /** The number of successful corrections upon CRC failure */
        unsigned long corrected_crc_failures;
        /** The number of successful corrections of SN wraparound upon CRC failure */
        unsigned long corrected_sn_wraparounds;
        /** The number of successful corrections of incorrect SN updates upon CRC
         *  failure */
        unsigned long corrected_wrong_sn_updates;

        /** The number of (possible) lost packet(s) before last packet */
        unsigned long nr_lost_packets;
        /** The number of packet(s) before the last packet if late */
        unsigned long nr_misordered_packets;
        /** Is last packet a (possible) duplicated packet? */
        bool is_duplicated;
};


typedef bool (*rohc_decomp_new_context_t)(const struct rohc_decomp_ctxt *const context,
                                          void **const persist_ctxt,
                                          struct rohc_decomp_volat_ctxt *const volat_ctxt)
        __attribute__((warn_unused_result, nonnull(1, 2, 3)));

typedef void (*rohc_decomp_free_context_t)(void *const persist_ctxt,
                                           const struct rohc_decomp_volat_ctxt *const volat_ctxt)
        __attribute__((nonnull(2)));

typedef rohc_packet_t (*rohc_decomp_detect_pkt_type_t) (const struct rohc_decomp_ctxt *const context,
                                                        const uint8_t *const rohc_packet,
                                                        const size_t rohc_length,
                                                        const size_t large_cid_len)
        __attribute__((warn_unused_result, nonnull(1, 2)));

typedef bool (*rohc_decomp_parse_pkt_t)(const struct rohc_decomp_ctxt *const context,
                                        const struct rohc_buf rohc_packet,
                                        const size_t large_cid_len,
                                        rohc_packet_t *const packet_type,
                                        struct rohc_decomp_crc *const extr_crc,
                                        void *const extr_bits,
                                        size_t *const rohc_hdr_len)
        __attribute__((warn_unused_result, nonnull(1, 4, 5, 6, 7)));

typedef bool (*rohc_decomp_decode_bits_t)(const struct rohc_decomp_ctxt *const context,
                                          const void *const extr_bits,
                                          const size_t payload_len,
                                          void *const decoded_values)
        __attribute__((warn_unused_result, nonnull(1, 2, 4)));

typedef rohc_status_t (*rohc_decomp_build_hdrs_t)(const struct rohc_decomp *const decomp,
                                                  const struct rohc_decomp_ctxt *const context,
                                                  const rohc_packet_t packet_type,
                                                  const struct rohc_decomp_crc *const extr_crc,
                                                  const void *const decoded_values,
                                                  const size_t payload_len,
                                                  struct rohc_buf *const uncomp_hdrs,
                                                  size_t *const uncomp_hdrs_len)
        __attribute__((warn_unused_result, nonnull(1, 2, 4, 5, 7, 8)));

typedef void (*rohc_decomp_update_ctxt_t)(struct rohc_decomp_ctxt *const context,
                                          const void *const decoded_values,
                                          const size_t payload_len,
                                          bool *const do_change_mode)
        __attribute__((nonnull(1, 2, 4)));

typedef bool (*rohc_decomp_attempt_repair_t)(const struct rohc_decomp *const decomp,
                                             const struct rohc_decomp_ctxt *const context,
                                             const struct rohc_ts pkt_arrival_time,
                                             struct rohc_decomp_crc_corr_ctxt *const crc_corr,
                                             void *const extr_bits)
        __attribute__((warn_unused_result, nonnull(1, 2, 4, 5)));

typedef uint32_t (*rohc_decomp_get_sn_t)(const struct rohc_decomp_ctxt *const context)
        __attribute__((warn_unused_result, nonnull(1)));


/**
 * @brief The ROHC decompression profile.
 *
 * The object defines a ROHC profile. Each field must be filled in
 * for each new profile.
 */
struct rohc_decomp_profile
{
        /** The profile ID as reserved by IANA */
        const rohc_profile_t id;

        /** The maximum number of bits of the Master Sequence Number (MSN) */
        const size_t msn_max_bits;

        /** @brief The handler used to create the profile-specific part of the
         *         decompression context */
        rohc_decomp_new_context_t new_context;

        /** @brief The handler used to destroy the profile-specific part of the
         *         decompression context */
        rohc_decomp_free_context_t free_context;

        /** The handler used to detect the type of the ROHC packet */
        rohc_decomp_detect_pkt_type_t detect_pkt_type;

        /* The handler used to parse a ROHC packet */
        rohc_decomp_parse_pkt_t parse_pkt;

        /* The handler used to decode the bits extracted from a ROHC packet */
        rohc_decomp_decode_bits_t decode_bits;

        /* The handler used to build the uncompressed packet after decoding */
        rohc_decomp_build_hdrs_t build_hdrs;

        /* The handler used to update the context after successful decompression */
        rohc_decomp_update_ctxt_t update_ctxt;

        /* The handler used to attempt packet/context correction upon CRC failure */
        rohc_decomp_attempt_repair_t attempt_repair;

        /* The handler used to retrieve the Sequence Number (SN) */
        rohc_decomp_get_sn_t get_sn;
};

#endif

---