tools/mi4.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 Dave Chapman
  11  *
  12  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 /*
  25  * CRC32 implementation taken from:
  26  *
  27  * efone - Distributed internet phone system.
  28  *
  29  * (c) 1999,2000 Krzysztof Dabrowski
  30  * (c) 1999,2000 ElysiuM deeZine
  31  *
  32  * This program is free software; you can redistribute it and/or
  33  * modify it under the terms of the GNU General Public License
  34  * as published by the Free Software Foundation; either version
  35  * 2 of the License, or (at your option) any later version.
  36  *
  37  */
  38
  39 /* based on implementation by Finn Yannick Jacobs */
  40
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43
  44 /* crc_tab[] -- this crcTable is being build by chksum_crc32GenTab().
  45  *              so make sure, you call it before using the other
  46  *              functions!
  47  */
  48 static unsigned int crc_tab[256];
  49
  50 /* chksum_crc() -- to a given block, this one calculates the
  51  *                              crc32-checksum until the length is
  52  *                              reached. the crc32-checksum will be
  53  *                              the result.
  54  */
  55 static unsigned int chksum_crc32 (unsigned char *block, unsigned int length)
  56 {
  57    register unsigned long crc;
  58    unsigned long i;
  59
  60    crc = 0;
  61    for (i = 0; i < length; i++)
  62    {
  63       crc = ((crc >> 8) & 0x00FFFFFF) ^ crc_tab[(crc ^ *block++) & 0xFF];
  64    }
  65    return (crc);
  66 }
  67
  68 /* chksum_crc32gentab() --      to a global crc_tab[256], this one will
  69  *                              calculate the crcTable for crc32-checksums.
  70  *                              it is generated to the polynom [..]
  71  */
  72
  73 static void chksum_crc32gentab (void)
  74 {
  75    unsigned long crc, poly;
  76    int i, j;
  77
  78    poly = 0xEDB88320L;
  79    for (i = 0; i < 256; i++)
  80    {
  81       crc = i;
  82       for (j = 8; j > 0; j--)
  83       {
  84          if (crc & 1)
  85          {
  86             crc = (crc >> 1) ^ poly;
  87          }
  88          else
  89          {
  90             crc >>= 1;
  91          }
  92       }
  93       crc_tab[i] = crc;
  94    }
  95 }
  96
  97 static void int2le(unsigned int val, unsigned char* addr)
  98 {
  99     addr[0] = val & 0xFF;
 100     addr[1] = (val >> 8) & 0xff;
 101     addr[2] = (val >> 16) & 0xff;
 102     addr[3] = (val >> 24) & 0xff;
 103 }
 104
 105 int mi4_encode(char *iname, char *oname, int version, int magic,
 106                 char *model, char *type)
 107 {
 108     size_t len;
 109     int length;
 110     int mi4length;
 111     FILE *file;
 112     unsigned int crc = 0;
 113     unsigned char *outbuf;
 114
 115     file = fopen(iname, "rb");
 116     if (!file) {
 117        perror(iname);
 118        return -1;
 119     }
 120     fseek(file,0,SEEK_END);
 121     length = ftell(file);
 122
 123     fseek(file,0,SEEK_SET);
 124
 125     /* Add 4 bytes to length (for magic), the 0x200 byte header and
 126        then round to an even 0x400 bytes
 127      */
 128     mi4length = (length+4+0x200+0x3ff)&~0x3ff;
 129
 130     outbuf = malloc(mi4length);
 131
 132     if ( !outbuf ) {
 133        printf("out of memory!\n");
 134        return -1;
 135     }
 136
 137     /* Clear the buffer to zero */
 138     memset(outbuf, 0, mi4length);
 139
 140     len = fread(outbuf+0x200, 1, length, file);
 141     if(len < (size_t)length) {
 142         perror(iname);
 143         return -2;
 144     }
 145     fclose(file);
 146
 147     /* We need to write some data into the actual image - before calculating
 148        the CRC. */
 149     int2le(0x00000100,   &outbuf[0x2e0]);   /* magic */
 150     int2le(magic,        &outbuf[0x2e4]);   /* magic */
 151     int2le(length+4,     &outbuf[0x2e8]);   /* length plus 0xaa55aa55 */
 152
 153     int2le(0xaa55aa55,   &outbuf[0x200+length]);  /* More Magic */
 154
 155     strncpy((char *)outbuf+0x1f8, type, 4);  /* type of binary (RBBL, RBOS) */
 156     strncpy((char *)outbuf+0x1fc, model, 4); /* 4 character model id */
 157
 158     /* Calculate CRC32 checksum */
 159     chksum_crc32gentab ();
 160     crc = chksum_crc32 (outbuf+0x200,mi4length-0x200);
 161
 162     strncpy((char *)outbuf, "PPOS", 4);     /* Magic */
 163     int2le(version,      &outbuf[0x04]);    /* .mi4 version */
 164     int2le(length+4,     &outbuf[0x08]);    /* Length of firmware plus magic */
 165     int2le(crc,          &outbuf[0x0c]);    /* CRC32 of mi4 file */
 166     int2le(0x00000002,   &outbuf[0x10]);    /* Encryption type: 2 = TEA */
 167     int2le(mi4length,    &outbuf[0x14]);    /* Total .mi4 length */
 168     int2le(mi4length-0x200, &outbuf[0x18]); /* Length of plaintext part */
 169
 170     /* v3 files require a dummy DSA signature */
 171     if (version == 0x00010301) {
 172         outbuf[0x2f]=0x01;
 173     }
 174
 175     file = fopen(oname, "wb");
 176     if (!file) {
 177         perror(oname);
 178         return -3;
 179     }
 180
 181     len = fwrite(outbuf, 1, mi4length, file);
 182     if(len < (size_t)length) {
 183         perror(oname);
 184         return -4;
 185     }
 186
 187     fclose(file);
 188
 189     fprintf(stderr, "File encoded successfully\n" );
 190
 191     return 0;
 192 }