c_udp.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 c_udp.h
 * @brief ROHC compression context for the UDP profile.
 * @author Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author The hackers from ROHC for Linux
 */

#ifndef C_UDP_H
#define C_UDP_H

#include <netinet/ip.h>
#include <netinet/udp.h>

#include "c_generic.h"


/**
 * @brief Define the UDP-specific temporary variables in the profile compression
 *        context.
 *
 * This object must be used by the UDP-specific decompression context sc_udp_context.
 *
 * @see sc_udp_context
 */
struct udp_tmp_vars
{
        /// The number of UDP fields that changed in the UDP header
        int send_udp_dynamic;
};


/**
 * @brief Define the UDP part of the profile decompression context.
 *
 * This object must be used with the generic part of the decompression
 * context c_generic_context.
 *
 * @see c_generic_context
 */
struct sc_udp_context
{
        /// The number of times the checksum field was added to the compressed header
        int udp_checksum_change_count;

        /// The previous UDP header
        struct udphdr old_udp;

        /// @brief UDP-specific temporary variables that are used during one single
        ///        compression of packet
        struct udp_tmp_vars tmp;
};


/*
 * Function prototypes.
 */

int c_udp_create(struct c_context *const context, const struct ip_packet *ip);

int c_udp_check_context(const struct c_context *context,
                        const struct ip_packet *ip);

int c_udp_encode(struct c_context *const context,
                 const struct ip_packet *ip,
                 const int packet_size,
                 unsigned char *const dest,
                 const int dest_size,
                 rohc_packet_t *const packet_type,
                 int *const payload_offset);

void udp_decide_state(struct c_context *const context);

int udp_code_UO_packet_tail(const struct c_context *context,
                            const unsigned char *next_header,
                            unsigned char *const dest,
                            int counter);

int udp_code_static_udp_part(const struct c_context *context,
                             const unsigned char *next_header,
                             unsigned char *const dest,
                             int counter);


#endif