tools/firmware-utils/src/dgn3500sum.c

   1 /* **************************************************************************
   2
   3    This program creates a modified 16bit checksum used for the Netgear
   4    DGN3500 series routers. The difference between this and a standard
   5    checksum is that every 0x100 bytes added 0x100 have to be subtracted
   6    from the sum.
   7
   8    (C) 2013 Marco Antonio Mauro <marcus90 at gmail.com>
   9
  10    Based on previous unattributed work.
  11
  12    This program is free software; you can redistribute it and/or modify
  13    it under the terms of the GNU General Public License as published by
  14    the Free Software Foundation; either version 2 of the License, or
  15    (at your option) any later version.
  16
  17    This program is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  20    General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program; if not, write to the Free Software
  24    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  25
  26  ************************************************************************* */
  27
  28
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/stat.h>
  33
  34 unsigned char PidDataWW[70] =
  35 {
  36     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  37     0x33, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  38     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
  39     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  40     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  41 } ;
  42
  43 unsigned char PidDataDE[70] =
  44 {
  45     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  46     0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  47     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x00, 0x37,
  48     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  49     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  50 } ;
  51
  52 unsigned char PidDataNA[70] =
  53 {
  54     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  55     0x36, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  56     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
  57     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  58     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  59 } ;
  60
  61 /* *******************************************************************
  62    Reads the file into memory and returns pointer to the buffer. */
  63 static char *readfile(char *filename, int *size)
  64 {
  65         FILE            *fp;
  66         char            *buffer;
  67         struct stat     info;
  68
  69         if (stat(filename,&info)!=0)
  70                 return NULL;
  71
  72         if ((fp=fopen(filename,"r"))==NULL)
  73                 return NULL;
  74
  75         buffer=NULL;
  76         for (;;)
  77         {
  78                 if ((buffer=(char *)malloc(info.st_size+1))==NULL)
  79                         break;
  80
  81                 if (fread(buffer,1,info.st_size,fp)!=info.st_size)
  82                 {
  83                         free(buffer);
  84                         buffer=NULL;
  85                         break;
  86                 }
  87
  88                 buffer[info.st_size]='\0';
  89                 if(size) *size = info.st_size;
  90
  91                 break;
  92         }
  93
  94         (void)fclose(fp);
  95
  96         return buffer;
  97 }
  98
  99
 100 /* ******************************************************************* */
 101 int main(int argc, char** argv)
 102 {
 103   unsigned long start, i;
 104   char *endptr, *buffer, *p;
 105   int count;  // size of file in bytes
 106   unsigned short sum = 0, sum1 = 0;
 107   char sumbuf[8 + 8 + 1];
 108
 109   if(argc < 3) {
 110     printf("ERROR: Argument missing!\n\nUsage %s filename starting offset in hex [PID code]\n\n", argv[0]);
 111     return 1;
 112   }
 113
 114
 115   FILE *fp = fopen(argv[1], "a");
 116   if(!fp) {
 117     printf("ERROR: File not writeable!\n");
 118     return 1;
 119   }
 120   if(argc == 4)
 121   {
 122     printf("%s: PID type: %s\n", argv[0], argv[3]);
 123     if(strcmp(argv[3], "DE")==0)
 124       fwrite(PidDataDE, sizeof(PidDataDE), sizeof(char), fp);  /* write DE pid */
 125     else if(strcmp(argv[3], "NA")==0)
 126       fwrite(PidDataNA, sizeof(PidDataNA), sizeof(char), fp);  /* write NA pid */
 127     else /* if(strcmp(argv[3], "WW")) */
 128       fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp);  /* write WW pid */
 129   }
 130   else
 131     fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp);  /* write WW pid if unspecified */
 132
 133   fclose(fp);
 134
 135   /* Read the file to calculate the checksums */
 136   buffer = readfile(argv[1], &count);
 137   if(!buffer) {
 138     printf("ERROR: File %s not found!\n", argv[1]);
 139     return 1;
 140   }
 141
 142   p = buffer;
 143   for(i = 0; i < count; i++)
 144   {
 145         sum += p[i];
 146   }
 147
 148   start = strtol(argv[2], &endptr, 16);
 149   p = buffer+start;
 150   for(i = 0; i < count - start; i++)
 151   {
 152         sum1 += p[i];
 153   }
 154
 155   sprintf(sumbuf,"%04X%04X",sum1,sum);
 156   /* Append the 2 checksums to end of file */
 157   fp = fopen(argv[1], "a");
 158   if(!fp) {
 159     printf("ERROR: File not writeable!\n");
 160     return 1;
 161   }
 162   fwrite(sumbuf, 8, sizeof(char), fp);
 163   fclose(fp);
 164   free(buffer);
 165   return 0;
 166 }