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