154 lines
4.3 KiB
C
154 lines
4.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* **************************************************************************
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This program creates a modified 16bit checksum used for the Netgear
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DGN3500 series routers. The difference between this and a standard
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checksum is that every 0x100 bytes added 0x100 have to be subtracted
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from the sum.
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(C) 2013 Marco Antonio Mauro <marcus90 at gmail.com>
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Based on previous unattributed work.
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************************************************************************* */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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unsigned char PidDataWW[70] =
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{
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0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
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0x33, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
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0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
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0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
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} ;
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unsigned char PidDataDE[70] =
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{
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0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
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0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x00, 0x37,
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0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
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0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
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} ;
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unsigned char PidDataNA[70] =
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{
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0x73, 0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D, 0x00, 0x00, 0x00, 0x00, 0x59, 0x50, 0x35, 0x37, 0x32,
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0x36, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0x00, 0x37,
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0x32, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x00, 0x00, 0x73,
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0x45, 0x72, 0x43, 0x6F, 0x4D, 0x6D,
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} ;
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/* *******************************************************************
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Reads the file into memory and returns pointer to the buffer. */
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static char *readfile(char *filename, int *size)
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{
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FILE *fp;
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char *buffer;
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struct stat info;
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if (stat(filename,&info)!=0)
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return NULL;
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if ((fp=fopen(filename,"r"))==NULL)
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return NULL;
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buffer=NULL;
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for (;;)
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{
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if ((buffer=(char *)malloc(info.st_size+1))==NULL)
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break;
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if (fread(buffer,1,info.st_size,fp)!=info.st_size)
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{
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free(buffer);
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buffer=NULL;
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break;
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}
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buffer[info.st_size]='\0';
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if(size) *size = info.st_size;
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break;
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}
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(void)fclose(fp);
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return buffer;
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}
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/* ******************************************************************* */
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int main(int argc, char** argv)
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{
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unsigned long start, i;
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char *endptr, *buffer, *p;
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int count; // size of file in bytes
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unsigned short sum = 0, sum1 = 0;
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char sumbuf[8 + 8 + 1];
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if(argc < 3) {
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printf("ERROR: Argument missing!\n\nUsage %s filename starting offset in hex [PID code]\n\n", argv[0]);
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return 1;
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}
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FILE *fp = fopen(argv[1], "a");
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if(!fp) {
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printf("ERROR: File not writeable!\n");
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return 1;
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}
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if(argc == 4)
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{
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printf("%s: PID type: %s\n", argv[0], argv[3]);
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if(strcmp(argv[3], "DE")==0)
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fwrite(PidDataDE, sizeof(PidDataDE), sizeof(char), fp); /* write DE pid */
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else if(strcmp(argv[3], "NA")==0)
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fwrite(PidDataNA, sizeof(PidDataNA), sizeof(char), fp); /* write NA pid */
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else /* if(strcmp(argv[3], "WW")) */
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fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp); /* write WW pid */
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}
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else
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fwrite(PidDataWW, sizeof(PidDataWW), sizeof(char), fp); /* write WW pid if unspecified */
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fclose(fp);
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/* Read the file to calculate the checksums */
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buffer = readfile(argv[1], &count);
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if(!buffer) {
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printf("ERROR: File %s not found!\n", argv[1]);
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return 1;
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}
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p = buffer;
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for(i = 0; i < count; i++)
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{
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sum += p[i];
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}
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start = strtol(argv[2], &endptr, 16);
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p = buffer+start;
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for(i = 0; i < count - start; i++)
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{
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sum1 += p[i];
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}
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sprintf(sumbuf,"%04X%04X",sum1,sum);
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/* Append the 2 checksums to end of file */
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fp = fopen(argv[1], "a");
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if(!fp) {
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printf("ERROR: File not writeable!\n");
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return 1;
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}
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fwrite(sumbuf, 8, sizeof(char), fp);
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fclose(fp);
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free(buffer);
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return 0;
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}
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