openwrt/target/utils/src/dgfirmware.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3
   4
   5 #define IMG_SIZE     0x3e0000
   6
   7 #define KERNEL_START 0x020000
   8 #define KERNEL_SIZE  0x0b0000
   9
  10 #define ROOTFS_START 0x0d0000
  11 #define ROOTFS_SIZE  0x30ffb2
  12
  13 char* app_name;
  14
  15
  16
  17
  18 void print_usage(void)
  19 {
  20   fprintf(stderr, "usage: dgfirmware [<opts>] <img>\n");
  21   fprintf(stderr, "  <img>               firmware image filename\n");
  22   fprintf(stderr, "  <opts>  -h          print this message\n");
  23   fprintf(stderr, "          -f          fix the checksum\n");
  24   fprintf(stderr, "          -x  <file>  extract the rootfs file to <file>\n");
  25   fprintf(stderr, "          -xk <file>  extract the kernel to <file>\n");
  26   fprintf(stderr, "          -m  <file>  merge in rootfs fil\e from <file>\n");
  27   fprintf(stderr, "          -k  <file>  merge in kernel from <file>\n");
  28   fprintf(stderr, "          -w  <file>  write back the modified firmware\n");
  29 }
  30
  31
  32 unsigned char* read_img(const char *fname)
  33 {
  34   FILE *fp;
  35   int size;
  36   unsigned char *img;
  37
  38   fp = fopen(fname, "rb");
  39   if (fp == NULL) {
  40     perror(app_name);
  41     exit(-1);
  42   }
  43
  44   fseek(fp, 0, SEEK_END);
  45   size = ftell(fp);
  46
  47   if (size != IMG_SIZE) {
  48     fprintf(stderr, "%s: image file has wrong size\n", app_name);
  49     fclose(fp);
  50     exit(-1);
  51   }
  52
  53   rewind(fp);
  54
  55   img = malloc(IMG_SIZE);
  56   if (img == NULL) {
  57     perror(app_name);
  58     fclose(fp);
  59     exit(-1);
  60   }
  61
  62   if (fread(img, 1, IMG_SIZE, fp) != IMG_SIZE) {
  63     fprintf(stderr, "%s: can't read image file\n", app_name);
  64     fclose(fp);
  65     exit(-1);
  66   }
  67
  68   fclose(fp);
  69   return img;
  70 }
  71
  72
  73 void write_img(unsigned char* img, const char *fname)
  74 {
  75   FILE *fp;
  76
  77   fp = fopen(fname, "wb");
  78   if (fp == NULL) {
  79     perror(app_name);
  80     exit(-1);
  81   }
  82
  83   if (fwrite(img, 1, IMG_SIZE, fp) != IMG_SIZE) {
  84     fprintf(stderr, "%s: can't write image file\n", app_name);
  85     fclose(fp);
  86     exit(-1);
  87   }
  88 }
  89
  90
  91 void write_rootfs(unsigned char* img, const char *fname)
  92 {
  93   FILE *fp;
  94
  95   fp = fopen(fname, "wb");
  96   if (fp == NULL) {
  97     perror(app_name);
  98     exit(-1);
  99   }
 100
 101   if (fwrite(img+ROOTFS_START, 1, ROOTFS_SIZE, fp) != ROOTFS_SIZE) {
 102     fprintf(stderr, "%s: can't write image file\n", app_name);
 103     fclose(fp);
 104     exit(-1);
 105   }
 106 }
 107
 108
 109 void write_kernel(unsigned char* img, const char *fname)
 110 {
 111   FILE *fp;
 112
 113   fp = fopen(fname, "wb");
 114   if (fp == NULL) {
 115     perror(app_name);
 116     exit(-1);
 117   }
 118
 119   if (fwrite(img+KERNEL_START, 1, KERNEL_SIZE, fp) != KERNEL_SIZE) {
 120     fprintf(stderr, "%s: can't write kernel file\n", app_name);
 121     fclose(fp);
 122     exit(-1);
 123   }
 124 }
 125
 126
 127 unsigned char* read_rootfs(unsigned char* img, const char *fname)
 128 {
 129   FILE *fp;
 130   int size;
 131   int i;
 132
 133   for (i=ROOTFS_START; i<ROOTFS_START+ROOTFS_SIZE; i++)
 134     img[i] = 0xff;
 135
 136   fp = fopen(fname, "rb");
 137   if (fp == NULL) {
 138     perror(app_name);
 139     exit(-1);
 140   }
 141
 142   fseek(fp, 0, SEEK_END);
 143   size = ftell(fp);
 144
 145   if (size > ROOTFS_SIZE) {
 146     fprintf(stderr, "%s: rootfs image file is too big\n", app_name);
 147     fclose(fp);
 148     exit(-1);
 149   }
 150
 151   rewind(fp);
 152
 153   if (fread(img+ROOTFS_START, 1, size, fp) != size) {
 154     fprintf(stderr, "%s: can't read rootfs image file\n", app_name);
 155     fclose(fp);
 156     exit(-1);
 157   }
 158
 159   fclose(fp);
 160   return img;
 161 }
 162
 163
 164 unsigned char* read_kernel(unsigned char* img, const char *fname)
 165 {
 166   FILE *fp;
 167   int size;
 168   int i;
 169
 170   for (i=KERNEL_START; i<KERNEL_START+KERNEL_SIZE; i++)
 171     img[i] = 0xff;
 172
 173   fp = fopen(fname, "rb");
 174   if (fp == NULL) {
 175     perror(app_name);
 176     exit(-1);
 177   }
 178
 179   fseek(fp, 0, SEEK_END);
 180   size = ftell(fp);
 181
 182   if (size > KERNEL_SIZE) {
 183     fprintf(stderr, "%s: kernel binary file is too big\n", app_name);
 184     fclose(fp);
 185     exit(-1);
 186   }
 187
 188   rewind(fp);
 189
 190   if (fread(img+KERNEL_START, 1, size, fp) != size) {
 191     fprintf(stderr, "%s: can't read kernel file\n", app_name);
 192     fclose(fp);
 193     exit(-1);
 194   }
 195
 196   fclose(fp);
 197   return img;
 198 }
 199
 200
 201 int get_checksum(unsigned char* img)
 202 {
 203   short unsigned s;
 204
 205   s = img[0x3dfffc] + (img[0x3dfffd]<<8);
 206
 207   return s;
 208 }
 209
 210
 211 void set_checksum(unsigned char*img, unsigned short sum)
 212 {
 213   img[0x3dfffc] = sum & 0xff;
 214   img[0x3dfffd] = (sum>>8) & 0xff;
 215 }
 216
 217
 218 int compute_checksum(unsigned char* img)
 219 {
 220   int i;
 221   short s=0;
 222
 223   for (i=0; i<0x3dfffc; i++)
 224     s += img[i];
 225
 226   return s;
 227 }
 228
 229
 230 int main(int argc, char* argv[])
 231 {
 232   char *img_fname     = NULL;
 233   char *rootfs_fname  = NULL;
 234   char *kernel_fname  = NULL;
 235   char *new_img_fname = NULL;
 236
 237   int do_fix_checksum = 0;
 238   int do_write        = 0;
 239   int do_write_rootfs = 0;
 240   int do_read_rootfs  = 0;
 241   int do_write_kernel = 0;
 242   int do_read_kernel  = 0;
 243
 244   int i;
 245   unsigned char *img;
 246   unsigned short img_checksum;
 247   unsigned short real_checksum;
 248
 249   app_name = argv[0];
 250
 251   for (i=1; i<argc; i++) {
 252     if (!strcmp(argv[i], "-h")) {
 253       print_usage();
 254       return 0;
 255     }
 256     else if (!strcmp(argv[i], "-f")) {
 257       do_fix_checksum = 1;
 258     }
 259     else if (!strcmp(argv[i], "-x")) {
 260       if (i+1 >= argc) {
 261         fprintf(stderr, "%s: missing argument\n", app_name);
 262         return -1;
 263       }
 264       do_write_rootfs = 1;
 265       rootfs_fname = argv[i+1];
 266       i++;
 267     }
 268     else if (!strcmp(argv[i], "-xk")) {
 269       if (i+1 >= argc) {
 270         fprintf(stderr, "%s: missing argument\n", app_name);
 271         return -1;
 272       }
 273       do_write_kernel = 1;
 274       kernel_fname = argv[i+1];
 275       i++;
 276     }
 277     else if (!strcmp(argv[i], "-m")) {
 278       if (i+1 >= argc) {
 279         fprintf(stderr, "%s: missing argument\n", app_name);
 280         return -1;
 281       }
 282       do_read_rootfs = 1;
 283       rootfs_fname = argv[i+1];
 284       i++;
 285     }
 286     else if (!strcmp(argv[i], "-k")) {
 287       if (i+1 >= argc) {
 288         fprintf(stderr, "%s: missing argument\n", app_name);
 289         return -1;
 290       }
 291       do_read_kernel = 1;
 292       kernel_fname = argv[i+1];
 293       i++;
 294     }
 295     else if (!strcmp(argv[i], "-w")) {
 296       if (i+1 >= argc) {
 297         fprintf(stderr, "%s: missing argument\n", app_name);
 298         return -1;
 299       }
 300       do_write = 1;
 301       new_img_fname = argv[i+1];
 302       i++;
 303     }
 304     else if (img_fname != 0) {
 305       fprintf(stderr, "%s: too many arguments\n", app_name);
 306       return -1;
 307     }
 308     else {
 309       img_fname = argv[i];
 310     }
 311   }
 312
 313   if (img_fname == NULL) {
 314     fprintf(stderr, "%s: missing argument\n", app_name);
 315     return -1;
 316   }
 317
 318   if ((do_read_rootfs && do_write_rootfs) ||
 319       (do_read_kernel && do_write_kernel)) {
 320     fprintf(stderr, "%s: conflictuous options\n", app_name);
 321     return -1;
 322   }
 323
 324   printf ("** Read firmware file\n");
 325   img = read_img(img_fname);
 326
 327   printf ("Firmware product: %s\n", img+0x3dffbd);
 328   printf ("Firmware version: 1.%02d.%02d\n", (img[0x3dffeb] & 0x7f), img[0x3dffec]);
 329
 330   if (do_write_rootfs) {
 331     printf ("** Write rootfs file\n");
 332     write_rootfs(img, rootfs_fname);
 333   }
 334
 335   if (do_write_kernel) {
 336     printf ("** Write kernel file\n");
 337     write_kernel(img, kernel_fname);
 338   }
 339
 340   if (do_read_rootfs) {
 341     printf ("** Read rootfs file\n");
 342     read_rootfs(img, rootfs_fname);
 343     do_fix_checksum = 1;
 344   }
 345
 346   if (do_read_kernel) {
 347     printf ("** Read kernel file\n");
 348     read_kernel(img, kernel_fname);
 349     do_fix_checksum = 1;
 350   }
 351
 352   img_checksum = get_checksum(img);
 353   real_checksum = compute_checksum(img);
 354
 355   printf ("image checksum = %04x\n", img_checksum);
 356   printf ("real checksum  = %04x\n", real_checksum);
 357
 358   if (do_fix_checksum) {
 359     if (img_checksum != real_checksum) {
 360       printf ("** Bad Checksum, fix it\n");
 361       set_checksum(img, real_checksum);
 362     }
 363     else {
 364       printf ("** Checksum is correct, good\n");
 365     }
 366   }
 367
 368   if (do_write) {
 369     printf ("** Write image file\n");
 370     write_img(img, new_img_fname);
 371   }
 372
 373   free(img);
 374   return 0;
 375 }
 376