tools/firmware-utils/src/dgn3500sum.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* **************************************************************************
   3
   4    This program creates a modified 16bit checksum used for the Netgear
   5    DGN3500 series routers. The difference between this and a standard
   6    checksum is that every 0x100 bytes added 0x100 have to be subtracted
   7    from the sum.
   8
   9    (C) 2013 Marco Antonio Mauro <marcus90 at gmail.com>
  10
  11    Based on previous unattributed work.
  12
  13  ************************************************************************* */
  14
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <sys/stat.h>
  20
  21 unsigned char PidDataWW[70] =
  22 {
  23     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  24     0x33, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  25     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
  26     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  27     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  28 } ;
  29
  30 unsigned char PidDataDE[70] =
  31 {
  32     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  33     0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  34     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x00, 0x37,
  35     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  36     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  37 } ;
  38
  39 unsigned char PidDataNA[70] =
  40 {
  41     0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
  42     0x36, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  43     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
  44     0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
  45     0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
  46 } ;
  47
  48 /* *******************************************************************
  49    Reads the file into memory and returns pointer to the buffer. */
  50 static char *readfile(char *filename, int *size)
  51 {
  52         FILE            *fp;
  53         char            *buffer;
  54         struct stat     info;
  55
  56         if (stat(filename,&info)!=0)
  57                 return NULL;
  58
  59         if ((fp=fopen(filename,"r"))==NULL)
  60                 return NULL;
  61
  62         buffer=NULL;
  63         for (;;)
  64         {
  65                 if ((buffer=(char *)malloc(info.st_size+1))==NULL)
  66                         break;
  67
  68                 if (fread(buffer,1,info.st_size,fp)!=info.st_size)
  69                 {
  70                         free(buffer);
  71                         buffer=NULL;
  72                         break;
  73                 }
  74
  75                 buffer[info.st_size]='\0';
  76                 if(size) *size = info.st_size;
  77
  78                 break;
  79         }
  80
  81         (void)fclose(fp);
  82
  83         return buffer;
  84 }
  85
  86
  87 /* ******************************************************************* */
  88 int main(int argc, char** argv)
  89 {
  90   unsigned long start, i;
  91   char *endptr, *buffer, *p;
  92   int count;  // size of file in bytes
  93   unsigned short sum = 0, sum1 = 0;
  94   char sumbuf[8 + 8 + 1];
  95
  96   if(argc < 3) {
  97     printf("ERROR: Argument missing!\n\nUsage %s filename starting offset in hex [PID code]\n\n", argv[0]);
  98     return 1;
  99   }
 100
 101
 102   FILE *fp = fopen(argv[1], "a");
 103   if(!fp) {
 104     printf("ERROR: File not writeable!\n");
 105     return 1;
 106   }
 107   if(argc == 4)
 108   {
 109     printf("%s: PID type: %s\n", argv[0], argv[3]);
 110     if(strcmp(argv[3], "DE")==0)
 111       fwrite(PidDataDE, sizeof(PidDataDE), sizeof(char), fp);  /* write DE pid */
 112     else if(strcmp(argv[3], "NA")==0)
 113       fwrite(PidDataNA, sizeof(PidDataNA), sizeof(char), fp);  /* write NA pid */
 114     else /* if(strcmp(argv[3], "WW")) */
 115       fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp);  /* write WW pid */
 116   }
 117   else
 118     fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp);  /* write WW pid if unspecified */
 119
 120   fclose(fp);
 121
 122   /* Read the file to calculate the checksums */
 123   buffer = readfile(argv[1], &count);
 124   if(!buffer) {
 125     printf("ERROR: File %s not found!\n", argv[1]);
 126     return 1;
 127   }
 128
 129   p = buffer;
 130   for(i = 0; i < count; i++)
 131   {
 132         sum += p[i];
 133   }
 134
 135   start = strtol(argv[2], &endptr, 16);
 136   p = buffer+start;
 137   for(i = 0; i < count - start; i++)
 138   {
 139         sum1 += p[i];
 140   }
 141
 142   sprintf(sumbuf,"%04X%04X",sum1,sum);
 143   /* Append the 2 checksums to end of file */
 144   fp = fopen(argv[1], "a");
 145   if(!fp) {
 146     printf("ERROR: File not writeable!\n");
 147     return 1;
 148   }
 149   fwrite(sumbuf, 8, sizeof(char), fp);
 150   fclose(fp);
 151   free(buffer);
 152   return 0;
 153 }