src/rohc/d_ip.c

/*
    ROHC Project 2003 at Lulea University of Technology, Sweden.
    Authors: Andreas Vernersson <andver-8@student.luth.se>
             Daniel Pettersson <danpet-7@student.luth.se>
             Erik Soderstrom <soderstrom@yahoo.com>
             Fredrik Lindstrom <frelin-9@student.luth.se>
             Johan Stenmark <johste-8@student.luth.se>
             Martin Juhlin <juhlin@users.sourceforge.net>
             Mikael Larsson <larmik-9@student.luth.se>
             Robert Maxe <robmax-1@student.luth.se>
             
    Copyright (C) 2003 Andreas Vernersson, Daniel Pettersson, 
    Erik Soderström, Fredrik Lindström, Johan Stenmark, 
    Martin Juhlin, Mikael Larsson, Robert Maxe.  

    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
*/    
// IP-Only profile in decompressor

/* The decode functions decode the packet, control CRC
 * and if crc-fails the try a new decompression with a
 * other SN number. The decode functions returns some
 * kind of ROHC_ERROR or if it is correct decoded the
 * length of the decoded packet is returned.
*/

#include <asm/byteorder.h>

#include "rohc.h"
#include "decomp.h"

#include "d_ip.h"
#include "d_util.h"
#include "comp.h"
#include "c_util.h"

//--------------------------------------------------------- Helpfunctions

/* Decode a UO-0 package */
static int decode_uo0(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src,
        unsigned char * dest,
        int payload_size
        );

/* Decode a UO-1 package */
static int decode_uo1(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src2,
        unsigned char * dest,
        int payload_size
        );

/* Decode a UO-2 package */
static int decode_uor2(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src2,
        unsigned char * dest,
        int payload_size
        );

/* Decode a IR-Dyn package */
static int decode_irdyn(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src2,
        unsigned char * dest,
        int payload_size
        );

/* Decode extention 0 */
static int decode_extention0(unsigned char * src, int * sn, int * ip_id);

/* Decode extention 1 */
static int decode_extention1(unsigned char * src, int * sn, int * ip_id);

/* Decode extention 2 */
static int decode_extention2(unsigned char * src, int * sn, int * ip_id, int * ip_id2);

/* Decode extention 3
 *    - Updates random fields in the s_iponly_change
 *    - May update the SN value with 8 lower bits. sn_size is then changed
 */
static int decode_extention3(unsigned char * src, struct sd_context * context, struct sd_rohc *state,
        int * sn, int * sn_size, int * ip_id_changed, int * id2_updated);

// Make a copy of the "active"-struct to the "last"-struct.
static void syncronize(struct s_iponly_profile_data *);

// Decode package type
static int package_type(const unsigned char * p);

/* Deceide the extention type */
static int extention_type(const unsigned char * p);

/* Write a uncompressed IP v4 header */
static void write_uncompressed_ip4(
        struct s_iponly_change * active1,
        int ip_id,
        unsigned char * dest,
        int payload_size
        );


/* Copy the last-struct to active-struct. */
static void sync_on_failure(struct s_iponly_profile_data * pro);

/* Decode inner IP flags and fields. Storage the values
 * in a IP-head struct.
 */
static int decode_inner_header_flags(
        unsigned char * flags,
        unsigned char * fields,
        struct iphdr * ip,
        int * rnd, int * nbo);

/* Decode outer IP flags and fields. Storage the values
 * in a IP-head struct.
 */
static int decode_outer_header_flags(
        unsigned char * flags,
        unsigned char * fields,
        struct iphdr * ip,
        int * rnd, int * nbo,
        int * ip_changed);

/* A functions that decode uo0 and uo1 packets
 *
 */
static int help_to_decode_uo0_and_uo1(
        struct sd_context * context,
        unsigned char * src,
        unsigned char * dest,
        int * payload_size,
        int sn_bits,
        int number_of_sn_bits,
        int * id,
        int number_of_id_bits,
        int * id2,
        int * sn,
        int * calc_crc
        );

/* A functions that decode uor2 packets
 *
 */
static int help_to_decode_uor2(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src2,
        unsigned char * dest,
        int * payload_size,
        int * id,
        int * id2,
        int * sn,
        int * sn_size,
        int sn_bits,
        int ext,
        int * calc_crc
        );

/* The function that try to correct a packet after
 * a crc-failure.
 * It try with an other SN value.
 */
static int act_on_crc_failure(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src,
        unsigned char * dest,
        int sn_size,
        int * sn_curr1,
        int sn_bits,
        int * payload_size,
        int * id,
        int id_size,
        int * id2,
        int * calc_crc,
        int * real_crc,
        int ext
        );

static void update_inter_packet(struct s_iponly_profile_data * pro);
//---------------------------------------------------------- Code

// To allocate profile data
void * iponly_allocate_decode_data(void)
{
        struct s_iponly_profile_data * data;
        struct s_iponly_change * ch;
        void * p = kmalloc(sizeof(struct s_iponly_profile_data) + 4 * sizeof(struct s_iponly_change),
                GFP_ATOMIC);

        if (p==NULL) {
                rohc_debugf(0, "iponly_allocate_decode_data(): no mem for ip profile data\n");
                return NULL;
        }

        data = (struct s_iponly_profile_data *)p;
        ch = (struct s_iponly_change *)(data + 1);

        memset(p, 0, sizeof(struct s_iponly_profile_data) +
                4 * sizeof(struct s_iponly_change) );

        data->last1 = ch; ch++;
        data->active1 = ch; ch++;
        data->last2 = ch; ch++;
        data->active2 = ch;

        return p;
}

// To deallocate profile data
void iponly_free_decode_data(void * p)
{
        kfree(p);
}

// Decode an IR-package and initalize context
int iponly_decode_ir(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src,
        int copy_size,
        int dynamic_present,
        unsigned char * dest
        )
{
        struct s_iponly_profile_data * pro = context->data;
        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;

        unsigned char * s = src;
        unsigned char * d = dest;

        int size, sn;

        pro->current_packet_time = get_microseconds();

        // Ip4 static
        size = d_decode_static_ip4(s, &active1->ip);

        if (active1->ip.protocol == PROTOCOL_IP_IN_IP){
                pro->multiple_ip = 1;
                rohc_debugf(1, "Multiple IP header\n");
        }else{
                pro->multiple_ip = 0;
        }

        if (size == -1) {
                return ROHC_ERROR;
        }
        s += size; copy_size -= size;

        // If multiple-ip-header
        if(pro->multiple_ip){
                size = d_decode_static_ip4(s, &active2->ip);
                s += size; copy_size -= size;
                if (size == -1) {
                        return ROHC_ERROR;
                }
        }

        // Dynamic field
        if (dynamic_present) {
                size = d_decode_dynamic_ip4(s, &active1->ip, &active1->rnd, &active1->nbo);
                s += size; copy_size -= (size + 2);

                // If multiple-ip-header
                if(pro->multiple_ip){
                        size = d_decode_dynamic_ip4(s, &active2->ip, &active2->rnd, &active2->nbo);
                        s += size; copy_size -= size;
                }
                // Reset the correction-counter
                pro->counter = 0;

                // Get and set SN
                sn = ntohs(* ((__u16 *)s));
                d_lsb_init(&pro->sn, sn, -1);
                d_ip_id_init(&pro->ip_id1, ntohs(active1->ip.id), sn);
                s += 2;
                context->state = ROHC_FULL_CONTEXT;

                // If multiple-ip-header
                if(pro->multiple_ip){
                        d_ip_id_init(&pro->ip_id2, ntohs(active2->ip.id), sn);
                }


        } else if (context->state != ROHC_FULL_CONTEXT) {
                // in static/no context and not get dynamic part
                return ROHC_ERROR;
        }


        // Header write
        if (pro->multiple_ip){
                write_uncompressed_ip4(active1, ntohs(active1->ip.id), d, copy_size+sizeof(struct iphdr));
                d += sizeof(struct iphdr);
                write_uncompressed_ip4(active2, ntohs(active2->ip.id), d, copy_size);

        }else{
                write_uncompressed_ip4(active1, ntohs(active1->ip.id), d, copy_size);
        }
        d += sizeof(struct iphdr);

        // Syncronizerar strukterna
        syncronize(pro);

        // Update the inter-packet variable
        update_inter_packet(pro);

        // Copy payload
        if (copy_size == 0) return ROHC_OK_NO_DATA;

        memcpy(d, s, copy_size);

        // Statistics:
        context->header_compressed_size += s - src;
        c_add_wlsb(context->header_16_compressed, 0,0, s - src);
        context->header_uncompressed_size += (pro->multiple_ip+1)*sizeof(struct iphdr);
        c_add_wlsb(context->header_16_uncompressed, 0, 0, (pro->multiple_ip+1)*sizeof(struct iphdr));

        return copy_size + (pro->multiple_ip + 1) * sizeof(struct iphdr);
}

// Calculate the size of data in an IR-package.
// return : size or zero.
int iponly_detect_ir_size(unsigned char * first_byte, int second_byte_add)
{
        int ret = 10;
        int d = GET_BIT_0(first_byte);
        if (d) ret += 5 + 2;
        if (first_byte[second_byte_add + 2] != 0x40) return 0;
        if (first_byte[second_byte_add + 3] == PROTOCOL_IP_IN_IP){
                ret += 10;
                if (d) ret += 5;
                if (first_byte[second_byte_add + 12] != 0x40) return 0;
        }
        return ret;
}

// Calculate the size of data in an IR-package.
// return : size or zero.
int iponly_detect_ir_dyn_size(unsigned char * first_byte, struct sd_context *c)
{
        struct s_iponly_profile_data * pro = c->data;
        if (pro->active1->ip.protocol == PROTOCOL_IP_IN_IP) return 12;
        return 7;
}

// Decode all package except IR-package.
int iponly_decode(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src,
        int size,
        int second_byte,
        unsigned char * dest
        )
{
        struct s_iponly_profile_data * pro = context->data;
        // ---- DEBUG ----
        int i; unsigned char * p;

        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;
        struct s_iponly_change * last1 = pro->last1;
        struct s_iponly_change * last2 = pro->last2;

        pro->current_packet_time = get_microseconds();

        rohc_debugf(2,"(iponly_decode) nbo = %d rnd = %d\n", last1->nbo, last1->rnd);
        if (pro->multiple_ip){
                rohc_debugf(2,"Multiple ip-header\n");
                rohc_debugf(2,"(iponly_decode) nbo2 = %d rnd2 = %d\n", last2->nbo, last2->rnd);
        }
        if (memcmp(active1, last1, sizeof(struct s_iponly_change)) != 0) {
                rohc_debugf(0,"(iponly_decode) last1 and active1 struct is not synchronized\n");
                p = (unsigned char *)last1;
                for (i = 0; i < sizeof(struct s_iponly_change); i++) {
                        rohc_debugf(1, "%2x ", p[i]);
                }
                rohc_debugf(1, "\nvs\n");
                p = (unsigned char *)active1;
                for (i = 0; i < sizeof(struct s_iponly_change); i++) {
                        rohc_debugf(1, "%2x ", p[i]);
                }
                rohc_debugf(1,"\n");
        }
        if (memcmp(active2, last2, sizeof(struct s_iponly_change)) != 0) {
                rohc_debugf(0,"(iponly_decode) last2 and active2 struct is not synchronized\n");
                p = (unsigned char *)last2;
                for (i = 0; i < sizeof(struct s_iponly_change); i++) {
                        rohc_debugf(1,"%2x ", p[i]);
                }
                rohc_debugf(1,"\nvs\n");
                p = (unsigned char *)active2;
                for (i = 0; i < sizeof(struct s_iponly_change); i++) {
                        rohc_debugf(1,"%2x ", p[i]);
                }
                rohc_debugf(1,"\n");
        }
        // ---- DEBUG ----

        if (context->state == ROHC_NO_CONTEXT) return ROHC_ERROR;

        switch(package_type(src)) {
        case PACKAGE_UO_0:
                pro->package_type = PACKAGE_UO_0;
                if (context->state  == ROHC_STATIC_CONTEXT) return ROHC_ERROR;
                return decode_uo0(state, context, src, src + second_byte,
                        dest, size - second_byte);
        case PACKAGE_UO_1:
                pro->package_type = PACKAGE_UO_1;
                if (context->state  == ROHC_STATIC_CONTEXT) return ROHC_ERROR;
                return decode_uo1(state, context, src, src + second_byte,
                        dest, size - second_byte);
        case PACKAGE_UOR_2:
                pro->package_type = PACKAGE_UOR_2;
                return decode_uor2(state, context, src, src + second_byte,
                        dest, size - second_byte);
        case PACKAGE_IR_DYN:
                return decode_irdyn(state, context, src, src + second_byte,
                        dest, size - second_byte);
        default:
                rohc_debugf(0,"(Ip-only) Unknown package.\n");
                return ROHC_ERROR;
        }
}

static int iponly_get_sn(struct sd_context * context)
{
        struct s_iponly_profile_data * pro = context->data;
        return d_get_lsb_ref(&pro->sn);
}

static struct s_profile d_ip_profile = {4, "1.0", "IP / Decompressor",
        iponly_decode,
        iponly_decode_ir,
        iponly_allocate_decode_data,
        iponly_free_decode_data,
        iponly_detect_ir_size,
        iponly_detect_ir_dyn_size,
        iponly_get_sn
        };

struct s_profile * iponly_profile_create()
{
        return &d_ip_profile;
}

// --------------------------------------------------------- Package type decoder

/* Decode a UO-0 package */
 static int decode_uo0(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src,
        unsigned char * dest,
        int payload_size
        )
{
        unsigned char *saved_src = src;
        struct s_iponly_profile_data * pro = context->data;
        int multiple_ip = pro->multiple_ip;
        int id, id2=-1, sn, sn_bits = GET_BIT_3_6(head), sn_size = 4;
        int calc_crc, real_crc = GET_BIT_0_2(head);
        int extra_fields = 0, org_payload_size = payload_size;
        // Do the decoding / find ip-id
        extra_fields = help_to_decode_uo0_and_uo1(context, src, dest, &payload_size, sn_bits, sn_size , &id, 0 , &id2, &sn, &calc_crc);

        if (calc_crc != real_crc) {
                rohc_debugf(0,"UO-0: CRC failure (calc) %x vs %x (real)\n",
                        calc_crc, real_crc);

                payload_size = org_payload_size;
                act_on_crc_failure(0,context, src, dest, sn_size, &sn, sn_bits, &payload_size, &id, 0, &id2, &calc_crc, &real_crc, 0);
                return ROHC_ERROR_CRC;
        }

        // if any crc-correction then three correct packet need to pass crc
        if(pro->counter){
                if(pro->counter==1){

                        rohc_debugf(2,"Throw away packet, just 2 packages right so far\n");

                        pro->counter++;

                        // Update the inter-packet variable
                        update_inter_packet(pro);
                        syncronize(pro);

                        d_lsb_sync_ref(&pro->sn);
                        d_lsb_update(&pro->sn, sn);
                        d_ip_id_update(&pro->ip_id1, id, sn);
                        if (pro->multiple_ip)
                                d_ip_id_update(&pro->ip_id2, id2, sn);

                        return ROHC_ERROR_CRC;

                }else if(pro->counter==2){
                        pro->counter = 0;
                        rohc_debugf(2,"The rapair is deemed successful\n");
                }else{
                        rohc_debugf(2,"XX Should not happen XX\n");
                }
        }

        src += extra_fields;

        // Update the inter-packet variable
        update_inter_packet(pro);
        syncronize(pro);

        // Update lsb and id structs on CRC-success
        d_lsb_sync_ref(&pro->sn);
        d_lsb_update(&pro->sn, sn);
        d_ip_id_update(&pro->ip_id1, id, sn);
        if (pro->multiple_ip){
                d_ip_id_update(&pro->ip_id2, id2, sn);
                dest += sizeof(struct iphdr);
        }

        // Payload
        dest += sizeof(struct iphdr);
        memcpy(dest, src, payload_size);

        // Statistics:
        context->header_compressed_size += src - saved_src;
        c_add_wlsb(context->header_16_compressed, 0,0, src - saved_src);
        context->header_uncompressed_size += (multiple_ip+1)*sizeof(struct iphdr);
        c_add_wlsb(context->header_16_uncompressed, 0, 0, (multiple_ip+1)*sizeof(struct iphdr));

        return payload_size + (multiple_ip + 1) * sizeof(struct iphdr);
}


/* Decode a UO-1 package */
static int decode_uo1(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src,
        unsigned char * dest,
        int payload_size
        )
{
        unsigned char *saved_src = src;
        struct s_iponly_profile_data * pro = context->data;

        int id = GET_BIT_0_5(head), id2=-1;
        int sn, sn_bits = GET_BIT_3_7(src), sn_size = 5;
        int org_payload_size, extra_fields=0;
        int calc_crc, real_crc = GET_BIT_0_2(src);
        src++; payload_size--;
        org_payload_size = payload_size;

        // Decode the id and sn
        extra_fields = help_to_decode_uo0_and_uo1(context, src, dest, &payload_size, sn_bits, sn_size , &id, 6 , &id2, &sn, &calc_crc);

        if (calc_crc != real_crc) {
                rohc_debugf(0,"UO-1: CRC failure (calc) %x vs %x (real)\n",
                        calc_crc, real_crc);
                payload_size = org_payload_size;
                act_on_crc_failure(0,context, src, dest, sn_size, &sn, sn_bits, &payload_size, &id, 6, &id2, &calc_crc, &real_crc, 0);
                return ROHC_ERROR_CRC;
        }

        if(pro->counter){
                if(pro->counter==1){

                        rohc_debugf(2,"Throw away packet, just 2 packages right so far\n");

                        pro->counter++;
                        // Update the inter-packet variable

                        update_inter_packet(pro);
                        syncronize(pro);

                        d_lsb_sync_ref(&pro->sn);
                        d_lsb_update(&pro->sn, sn);
                        d_ip_id_update(&pro->ip_id1, id, sn);
                        if (pro->multiple_ip)
                                d_ip_id_update(&pro->ip_id2, id2, sn);

                        return ROHC_ERROR_CRC;

                }else if(pro->counter==2){
                        pro->counter = 0;
                        rohc_debugf(2,"The rapair is deemed successful\n");
                }else{
                        rohc_debugf(2,"XX Should not happen XX\n");
                }
        }

        src += extra_fields;

        // Update the inter-packet variable
        update_inter_packet(pro);

        syncronize(pro);

        d_lsb_sync_ref(&pro->sn);
        d_lsb_update(&pro->sn, sn);
        d_ip_id_update(&pro->ip_id1, id, sn);
        if (pro->multiple_ip){
                d_ip_id_update(&pro->ip_id2, id2, sn);
                dest += sizeof(struct iphdr);
        }

        // Payload
        dest += sizeof(struct iphdr);
        memcpy(dest, src, payload_size);

        // Statistics:
        context->header_compressed_size += src - saved_src;
        c_add_wlsb(context->header_16_compressed, 0,0, src - saved_src);
        context->header_uncompressed_size += (pro->multiple_ip+1)*sizeof(struct iphdr);
        c_add_wlsb(context->header_16_uncompressed, 0, 0, (pro->multiple_ip+1)*sizeof(struct iphdr));

        return payload_size + (pro->multiple_ip + 1)  * sizeof(struct iphdr);
}


/* Decode a UO-2 package */
static int decode_uor2(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src,
        unsigned char * dest,
        int payload_size
        )
{
        unsigned char *saved_src = src;
        struct s_iponly_profile_data * pro = context->data;

        int org_payload_size = payload_size, extra_fields = 0;
        int sn_size = 0;
        int id = 0, id2 = 0, multiple_id = pro->multiple_ip;
        int calc_crc = 0;
        int sn_bits = GET_BIT_0_4(head) , sn = 0;
        int real_crc = GET_BIT_0_6(src);
        int ext = GET_BIT_7(src);
        src++;

        // Decode
        extra_fields = help_to_decode_uor2(state, context, src, dest, &payload_size, &id, &id2, &sn, &sn_size, sn_bits, ext, &calc_crc);

        if (calc_crc != real_crc) {
                rohc_debugf(0,"UOR-2: CRC failure (calc) %x vs %x (real)\n",
                calc_crc, real_crc);
                payload_size = org_payload_size;
                id =0 ; id2 = 0; calc_crc = 0;
                act_on_crc_failure(state, context, src, dest, sn_size, &sn, sn_bits, &payload_size, &id, 0, &id2, &calc_crc, &real_crc, ext);
                return ROHC_ERROR_CRC;
        }

        if(pro->counter){
                if(pro->counter==1){

                        rohc_debugf(2,"Throw away packet, just 2 packages right so far\n");

                        pro->counter++;
                        // Update the inter-packet variable

                        update_inter_packet(pro);
                        syncronize(pro);

                        d_lsb_sync_ref(&pro->sn);
                        d_lsb_update(&pro->sn, sn);
                        d_ip_id_update(&pro->ip_id1, id, sn);
                        if (pro->multiple_ip)
                                d_ip_id_update(&pro->ip_id2, id2, sn);

                        return ROHC_ERROR_CRC;

                }else if(pro->counter==2){
                        pro->counter = 0;
                        rohc_debugf(2,"The rapair is deemed successful\n");
                }else{
                        rohc_debugf(2,"XX Should not happen XX\n");
                }
        }

        context->state  = ROHC_FULL_CONTEXT;

        src += extra_fields;

        // if crc success
        syncronize(pro);

        // Update the inter-packet variable
        update_inter_packet(pro);

        // Update
        d_lsb_sync_ref(&pro->sn);
        d_lsb_update(&pro->sn, sn);
        d_ip_id_update(&pro->ip_id1, id, sn);
        if (pro->multiple_ip){
                d_ip_id_update(&pro->ip_id2, id2, sn);
                dest += sizeof(struct iphdr);
                rohc_debugf(2,"Decomps reference ID2 = %d SN = %d\n",pro->ip_id2.id_ref,pro->ip_id2.sn_ref );
        }
        // Payload
        dest += sizeof(struct iphdr);
        memcpy(dest, src, payload_size);
        rohc_debugf(2,"Decomps reference ID1 = %d SN = %d\n",pro->ip_id1.id_ref,pro->ip_id1.sn_ref );
        rohc_debugf(2,"Decomps reference SN = %d\n",d_get_lsb_ref(&pro->sn));

        // Statistics:
        context->header_compressed_size += src - saved_src;
        c_add_wlsb(context->header_16_compressed, 0,0, src - saved_src);
        context->header_uncompressed_size += (multiple_id+1)*sizeof(struct iphdr);
        c_add_wlsb(context->header_16_uncompressed, 0, 0, (multiple_id+1)*sizeof(struct iphdr));

        return payload_size + (multiple_id +1) *sizeof(struct iphdr);

}


/* Decode a IR-Dyn package */
static int decode_irdyn(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * head,
        unsigned char * src2,
        unsigned char * dest,
        int payload_size
        )
{
        unsigned char *saved_src = src2;
        struct s_iponly_profile_data * pro = context->data;
        //struct s_iponly_change * last1 = pro->last1;
        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;
        int sn = 0, size = d_decode_dynamic_ip4(src2, &active1->ip, &active1->rnd, &active1->nbo);
        src2 += size; payload_size -= size + 2;

        if( pro->multiple_ip ){
                size = d_decode_dynamic_ip4(src2, &active2->ip, &active2->rnd, &active2->nbo);
                src2 += size; payload_size -= size;
        }
        sn = ntohs(* ((__u16 *)src2));
        d_lsb_init(&pro->sn, sn, -1);
        d_ip_id_init(&pro->ip_id1,ntohs(active1->ip.id), sn);
        syncronize(pro);
        // reset the correction-counter
        pro->counter = 0;
        src2 += 2;

        if (pro->multiple_ip){
                d_ip_id_init(&pro->ip_id2,ntohs(active2->ip.id), sn);
                rohc_debugf(2,"Decomps reference ID2 = %d SN = %d\n",pro->ip_id2.id_ref,pro->ip_id2.sn_ref );
                write_uncompressed_ip4(active1, ntohs(active1->ip.id), dest, payload_size+sizeof(struct iphdr));
                dest += sizeof(struct iphdr);
                write_uncompressed_ip4(active2, ntohs(active2->ip.id), dest, payload_size);
        }else{
                write_uncompressed_ip4(active1, ntohs(active1->ip.id), dest, payload_size);
        }
        context->state = ROHC_FULL_CONTEXT;
        // Update the inter-packet variable
        update_inter_packet(pro);

        dest += sizeof(struct iphdr);
        memcpy(dest, src2, payload_size);
        rohc_debugf(2,"Decomps reference ID = %d SN = %d\n",pro->ip_id1.id_ref,pro->ip_id1.sn_ref );
        rohc_debugf(2,"Decomps reference SN = %d\n",d_get_lsb_ref(&pro->sn));

        // Statistics:
        context->header_compressed_size += src2 - saved_src;
        c_add_wlsb(context->header_16_compressed, 0,0, src2 - saved_src);
        context->header_uncompressed_size += (pro->multiple_ip+1)*sizeof(struct iphdr);
        c_add_wlsb(context->header_16_uncompressed, 0, 0, (pro->multiple_ip+1)*sizeof(struct iphdr));

        return payload_size + ((pro->multiple_ip)+1) * sizeof(struct iphdr);
}

/* a help function that does the decoding of uo0 and uo1 packets */
static int help_to_decode_uo0_and_uo1(
        struct sd_context * context,
        unsigned char * src,
        unsigned char * dest,
        int * payload_size,
        int sn_bits,
        int number_of_sn_bits,
        int * id,
        int number_of_id_bits,
        int * id2,
        int * sn,
        int * calc_crc
        )
{
        struct s_iponly_profile_data * pro = context->data;
        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;
        int field_counter = 0;

        *sn = d_lsb_decode(&pro->sn, sn_bits, number_of_sn_bits);

        if (active1->rnd) {
                *id = ntohs(*((__u16 *)src));
                src += 2; field_counter +=2; *payload_size -= 2;

        } else {
                if(number_of_id_bits)
                        *id = d_ip_id_decode(&pro->ip_id1, *id, number_of_id_bits, *sn);
                else
                        *id = d_ip_id_decode(&pro->ip_id1, 0, 0, *sn);
        }

        // If multiple ip header
        if (pro->multiple_ip){

                if (active2->rnd) {
                        *id2 = ntohs(*((__u16 *)src));

                        src +=2; field_counter +=2; *payload_size -= 2;
                } else {
                        *id2 = d_ip_id_decode(&pro->ip_id2, 0, 0, *sn);
                }
        }

        // Header write
        if (pro->multiple_ip){
                write_uncompressed_ip4(active1, *id, dest, *payload_size+sizeof(struct iphdr));
                write_uncompressed_ip4(active2, *id2, dest+sizeof(struct iphdr),*payload_size);

        }else{
                write_uncompressed_ip4(active1, *id, dest, *payload_size);
        }

        // Check CRC
        *calc_crc = crc_calculate(CRC_TYPE_3, dest, (pro->multiple_ip + 1) * sizeof(struct iphdr));

        return field_counter;
}

/* a function that does the decoding of uor2 packets */
static int help_to_decode_uor2(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src2,
        unsigned char * dest,
        int * payload_size,
        int * id,
        int * id2,
        int * sn,
        int * sn_size,
        int sn_bits,
        int ext,
        int * calc_crc
        )
{
        struct s_iponly_profile_data * pro = context->data;
        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;
        int  id2_updated = 0, size = 0;
        int  no_ip_id_update = 0;
        int field_counter = 0;

        *sn = sn_bits;

        if (ext) {
                // decode extention
                switch(extention_type(src2)) {
                case PACKAGE_EXT_0:
                        size = decode_extention0(src2, sn, id);
                        // ip_id_bits == 3
                        *sn_size = 8;
                        *sn = d_lsb_decode(&pro->sn, *sn, *sn_size );
                        *id = d_ip_id_decode(&pro->ip_id1, *id, 3, *sn);
                        *id2 = d_ip_id_decode(&pro->ip_id2, 0, 0, *sn);
                        break;

                case PACKAGE_EXT_1:
                        size = decode_extention1(src2, sn, id);
                        // ip_id bits == 11
                        *sn_size = 8;
                        *sn = d_lsb_decode(&pro->sn, *sn, *sn_size );
                        *id = d_ip_id_decode(&pro->ip_id1, *id, 11, *sn);
                        *id2 = d_ip_id_decode(&pro->ip_id2, 0, 0, *sn);
                        break;

                case PACKAGE_EXT_2:
                        size = decode_extention2(src2, sn, id, id2);
                        // ip_id bits == 8
                        *sn_size = 8;
                        *sn = d_lsb_decode(&pro->sn, *sn, *sn_size );
                        *id2 = d_ip_id_decode(&pro->ip_id1, *id, 8, *sn);//inner
                        *id = d_ip_id_decode(&pro->ip_id2, *id2, 11, *sn);//outer
                        break;

                case PACKAGE_EXT_3:
                        *sn_size = 5;
                        size = decode_extention3(src2, context, state, sn,
                                sn_size, &no_ip_id_update, &id2_updated);

                        rohc_debugf(2,"(iponly_decode) after ext 3 : nbo = %d rnd = %d\n", active1->nbo, active1->rnd);

                        *sn = d_lsb_decode(&pro->sn, *sn, *sn_size );

                        if (no_ip_id_update) {
                                *id = ntohs(active1->ip.id);
                        } else {
                                *id = d_ip_id_decode(&pro->ip_id1, 0, 0, *sn);
                        }
                        if( pro->multiple_ip ){
                                rohc_debugf(2,"(iponly_decode) after ext 3 : nbo2 = %d rnd2 = %d\n", active2->nbo, active2->rnd);

                                if (id2_updated){
                                        *id2 = ntohs(active2->ip.id);
                                }else
                                        *id2 = d_ip_id_decode(&pro->ip_id2, 0, 0, *sn);

                        }
                        break;
                }


                src2 += size;
                field_counter +=size;
                *payload_size -= size + 1;
        } else {
                // No extention
                *sn_size = 5;
                *sn = d_lsb_decode(&pro->sn, *sn , *sn_size);

                *id = d_ip_id_decode(&pro->ip_id1, 0, 0, *sn);
                if( pro->multiple_ip)
                        *id2 = d_ip_id_decode(&pro->ip_id1, 0, 0, *sn);
                *payload_size -= 1;
        }


        // Random IP ID ?
        if (active1->rnd) {
                *id = ntohs(*((__u16 *)src2));
                src2 +=2; field_counter +=2; *payload_size -= 2;
        }

        // Multiple ip-header

        if (( pro->multiple_ip )&&( active2->rnd )){
                *id2 = ntohs(*((__u16 *)src2));
                src2 +=2; field_counter +=2; *payload_size -= 2;
        }


        // Header write
        if (pro->multiple_ip){
                write_uncompressed_ip4(active1, *id, dest, *payload_size+sizeof(struct iphdr));
                write_uncompressed_ip4(active2, *id2, dest+sizeof(struct iphdr),*payload_size);
        }else{
                write_uncompressed_ip4(active1, *id, dest, *payload_size);
        }

        // CRC-check
        *calc_crc = crc_calculate(CRC_TYPE_7, dest, (pro->multiple_ip + 1) * sizeof(struct iphdr));

        return field_counter;
}


// ---------------------------------------------------------

/* Decode extention 0.
 *    - SN value is expanded with 3 lower bits
 *    - IP-ID is replaced with 3 bits
 */
static int decode_extention0(unsigned char * src, int * sn, int * ip_id)
{
        *sn = *sn << 3 | GET_BIT_3_5(src);
        *ip_id = GET_BIT_0_2(src);
        return 1;
}

/* Decode extention 1
 *    - SN value is expanded with 3 lower bits
 *    - IP-ID is replaced with 11 bits
 */
static int decode_extention1(unsigned char * src, int * sn, int * ip_id)
{
        *sn = *sn << 3 | GET_BIT_3_5(src);
        *ip_id = GET_BIT_0_2(src);

        src++;
        *ip_id = *ip_id << 8 | *src;

        return 2;
}

/* Decode extention 2
 *    - SN value is expanded with 3 lower bits
 *    - IP-ID is replaced with 8 bits
 */
static int decode_extention2(unsigned char * src, int * sn, int * ip_id, int * ip_id2)
{

        *sn = *sn << 3 | GET_BIT_3_5(src);
        *ip_id2 = GET_BIT_0_2(src);
        src++;

        *ip_id2 = *ip_id2 << 8 | *src;
        src++;

        *ip_id = *src;
        return 3;
}

/* Decode extention 3
 *    - Updates random fields in the s_iponly_change
 *    - May update the SN value with 8 lower bits. sn_size is then changed
 */
static int decode_extention3(
        unsigned char * src,
        struct sd_context * context,
        struct sd_rohc * state,
        int * sn,
        int * sn_size,
        int * ip_id_changed,
        int * update_id2
        )
{
        struct s_iponly_profile_data * pro = context->data;
        struct s_iponly_change * active1 = pro->active1;
        struct s_iponly_change * active2 = pro->active2;
        unsigned char * org = src;
        unsigned char * fields  = src + 1;
        int S = GET_BIT_5(src);
        int mode = GET_BIT_3_4(src);
        int I = GET_BIT_2(src);
        int ip = GET_BIT_1(src);
        int ip2 = GET_BIT_0(src);
        int size;

        src++;

        if (ip) fields++;
        if (ip2) fields++;

        if (S) {
                *sn = (*sn << 8) + *fields;
                *sn_size += 8;
                fields++;
        }

        if (ip) {
                if(pro->multiple_ip){
                        size = decode_inner_header_flags(src, fields, &active2->ip,
                        &active2->rnd, &active2->nbo);
                }else
                        size = decode_inner_header_flags(src, fields, &active1->ip,
                        &active1->rnd, &active1->nbo);
                fields += size;
        }
        if (I) {
                if(pro->multiple_ip){
                        active2->ip.id = *((__u16 *)fields);
                        fields += 2;
                        *update_id2 = 1;
                }else{
                        active1->ip.id = *((__u16 *)fields);
                        fields += 2;
                        *ip_id_changed = 1;
                }
        }
        if (ip2) {
                size = decode_outer_header_flags(src, fields, &active1->ip,
                        &active1->rnd, &active1->nbo, ip_id_changed);
                fields += size;
        }

        if(mode != context->mode){
                rohc_debugf(2,"mode is not equal on decomp and comp.\n");
                d_change_mode_feedback(state, context);
        }
        return fields - org;
}

// --------------------------------------------------------- Local utils functions

// Deceide what package type
static int package_type(const unsigned char * p)
{
        if (!GET_BIT_7(p)) {
                return PACKAGE_UO_0;
        } else if (!GET_BIT_6(p)) {
                return PACKAGE_UO_1;
        } else if (GET_BIT_5_7(p) == 6) {
                return PACKAGE_UOR_2;
        } else if (*p == 0xf8) {
                return PACKAGE_IR_DYN;
        } else if ( (*p & 0xfe) == 0xfc) {
                return PACKAGE_IR;
        } else {
                return PACKAGE_UNKNOWN;
        }
}

// Copy the active-structs to last-structs.
static void syncronize(struct s_iponly_profile_data * pro)
{
        memcpy(pro->last1, pro->active1, sizeof(struct s_iponly_change));
        memcpy(pro->last2, pro->active2, sizeof(struct s_iponly_change));
}

// Copy the last-structs to the active-structs.
static void sync_on_failure(struct s_iponly_profile_data * pro)
{
        memcpy(pro->active1, pro->last1, sizeof(struct s_iponly_change));
        memcpy(pro->active2, pro->last2, sizeof(struct s_iponly_change));
}

// Deceide the extention type
static int extention_type(const unsigned char * p)
{
        return GET_BIT_6_7(p);
}

/* Decode inner IP flags and fields. Storage the values
 * in a IP-head struct.
 */
static int decode_inner_header_flags(
        unsigned char * flags,
        unsigned char * fields,
        struct iphdr * ip,
        int * rnd, int * nbo)
{
        int size = 0;
        if (GET_BIT_7(flags)) {
                ip->tos = *fields;
                fields++; size++;
        }
        if (GET_BIT_6(flags)) {
                ip->ttl = *fields;
                fields++; size++;
        }
        if (GET_BIT_5(flags)) {
                ip->frag_off = htons(IP_DF);
        } else {
                ip->frag_off = 0;
        }
        if (GET_BIT_4(flags)) {
                ip->protocol = *fields;
                fields++; size++;
        }
        if (GET_BIT_3(flags)) {
                // TODO, list compression
                rohc_debugf(0,"Listcompression is not supported\n");
        }
        *nbo = GET_BIT_2(flags);
        *rnd = GET_BIT_1(flags);
        return size;
}

/* Decode outer IP flags and fields. Storage the values
 * in a IP-head struct.
 */
static int decode_outer_header_flags(
        unsigned char * flags,
        unsigned char * fields,
        struct iphdr * ip,
        int * rnd, int * nbo,
        int * updated_id)
{
        int size = 0;
        if (GET_BIT_7(flags)) {
                ip->tos = *fields;
                fields++; size++;
        }
        if (GET_BIT_6(flags)) {
                ip->ttl = *fields;
                fields++; size++;
        }
        if (GET_BIT_5(flags)) {
                ip->frag_off = htons(IP_DF);
        } else {
                ip->frag_off = 0;
        }
        if (GET_BIT_4(flags)) {
                ip->protocol = *fields;
                fields++; size++;
        }
        if (GET_BIT_3(flags)) {
                // TODO, list compression
                rohc_debugf(0,"Listcompression is not supported\n");
        }
        *nbo = GET_BIT_2(flags);
        *rnd = GET_BIT_1(flags);

        if (GET_BIT_0(flags)) {
                ip->id = *((__u16 *)fields);
                fields += 2; size += 2;
                *updated_id = 1;
        }
        return size;
}

/* Write a uncompressed IP v4 header */
static void write_uncompressed_ip4(
        struct s_iponly_change * active,
        int ip_id,
        unsigned char * dest,
        int payload_size
        )
{
        struct iphdr * ip = (struct iphdr *)dest;

        // --- static & some changing
        memcpy(dest, &active->ip, sizeof(struct iphdr));

        // --- ip-id
        ip->id = htons(ip_id);
        if (!active->nbo) ip->id = __swab16(ip->id);

        //--- Static-known fields
        ip->ihl = 5;

        //--- Interfered fields
        ip->tot_len = htons(payload_size + (ip->ihl * 4));
        ip->check = 0;
        ip->check = ip_fast_csum(dest, ip->ihl);
}


/*  This function try to repair the SN in one of two different ways
 *
 */
static int act_on_crc_failure(
        struct sd_rohc * state,
        struct sd_context * context,
        unsigned char * src,
        unsigned char * dest,
        int sn_size,
        int * sn,
        int sn_bits,
        int * payload_size,
        int * id,
        int id_size,
        int * id2,
        int * calc_crc,
        int * real_crc,
        int ext
        )
{
        struct s_iponly_profile_data * pro = context->data;

        int sn_ref = 0, intervall = 0;
        int sn_curr2 = 0, sn_curr1 = 0;
        int sn_update = 0;

        sync_on_failure(pro);

        if(CRC_ACTION){
                rohc_debugf(0,"Try to repair the CRC\n");

                if(pro->last_packet_time) //if last packettime == 0 then IR was just sent and ...
                        intervall = pro->current_packet_time - pro->last_packet_time;

                if(intervall > ((1 << sn_size)*(pro->inter_arrival_time))){
                        rohc_debugf(0,"ROHC: repair with the assumption:  SN LSB wraparound\n");
                        rohc_debugf(2,"inter_arrival_time = %d and current intervall is = %d\n", pro->inter_arrival_time, intervall);
                        rohc_debugf(2,"add %d to SN\n", 1 << sn_size);

                        // Try and update the SN
                        sn_ref = d_get_lsb_ref(&pro->sn);
                        sn_ref += (1 << sn_size);
                        d_lsb_sync_ref(&pro->sn);
                        d_lsb_update(&pro->sn, sn_ref);
                        *sn = d_lsb_decode(&pro->sn, sn_bits, sn_size );

                        pro->counter = 0;

                }else{
                        // try with the old sn_ref value

                        rohc_debugf(0,"ROHC: repair with the assumption: incorrect SN-updates\n");
                        rohc_debugf(2,"inter_arrival_time = %d and current intervall is = %d\n", pro->inter_arrival_time, intervall);

                        // save current referece value
                        sn_curr1 = d_get_lsb_ref(&pro->sn);
                        // test with old reference value
                        d_lsb_update(&pro->sn, d_get_lsb_old_ref(&pro->sn));

                        sn_curr2 = d_lsb_decode(&pro->sn, sn_bits, sn_size );

                        if( sn_curr2 == *sn){
                                rohc_debugf(2,"with old ref value we get the same sn\n");
                                return ROHC_ERROR_CRC;
                        }
                        *sn = sn_curr2;
                        d_lsb_update(&pro->sn, sn_curr2);
                        sn_update = 1;
                        pro->counter = 0;
                }
                rohc_debugf(2,"Try a new decompression with another sn \n");
                // Try a new decompression with another SN
                switch (pro->package_type){
                case PACKAGE_UO_0:
                //fall through
                case PACKAGE_UO_1:
                        help_to_decode_uo0_and_uo1(context, src, dest, payload_size, sn_bits, sn_size , id, id_size, id2, sn, calc_crc);
                        break;
                case PACKAGE_UOR_2:
                        *sn = sn_bits;
                        help_to_decode_uor2(state, context, src, dest, payload_size, id, id2, sn, &sn_size, sn_bits, ext, calc_crc);
                        break;
                default:
                        rohc_debugf(0,"(Ip-only) A existing packet?\n");
                        d_lsb_update(&pro->sn, sn_curr1);
                        return ROHC_ERROR_CRC;
                }

                if (*calc_crc != *real_crc){
                        rohc_debugf(0,"ROHC: CRC failure also on the second attempt (calc) %x vs %x (real)\n",*calc_crc, *real_crc);
                        pro->counter = 0;
                        if(sn_update)
                                d_lsb_update(&pro->sn, sn_curr1); //reference curr1 should be used
                        sync_on_failure(pro);
                        return ROHC_ERROR_CRC;
                }
                //CRC-pass
                rohc_debugf(2,"Update and sync with the new SN then throw away the packet\n");
                pro->counter++;
                update_inter_packet(pro);

                syncronize(pro);

                if(!sn_update){
                        d_lsb_sync_ref(&pro->sn);
                        d_lsb_update(&pro->sn, *sn);
                }else
                        d_lsb_update(&pro->sn, sn_curr2);

                d_ip_id_update(&pro->ip_id1, *id, *sn);
                if (pro->multiple_ip)
                        d_ip_id_update(&pro->ip_id2, *id2, *sn);

                return ROHC_ERROR_CRC;

        }else{
                return ROHC_ERROR_CRC;
        }
}

/* Update the inter-packet time, a sort of averange over the last inter-packet times */
static void update_inter_packet(struct s_iponly_profile_data * pro)
{
        int last_time = pro->last_packet_time;
        int delta = 0;
        rohc_debugf(2,"current time = %d and last time = %d\n", pro->current_packet_time, last_time);

        if (last_time)
                delta = pro->current_packet_time - last_time;
        pro->last_packet_time = pro->current_packet_time;
        if (pro->inter_arrival_time){
                pro->inter_arrival_time = (pro->inter_arrival_time >> WEIGHT_OLD) + (delta >> WEIGHT_NEW);

        } else
                pro->inter_arrival_time = delta;

        rohc_debugf(2,"inter_arrival_time = %d and current arrival delta is = %d\n", pro->inter_arrival_time, delta);
}
Revision:	1.1
Committed:	Sun Feb 8 06:02:44 2004 UTC (20 years, 4 months ago) by pcg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	ROHC-IMPORT-2004-02-08
Log Message:	* empty log message *