nexmon – Rev 1

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#define _XOPEN_SOURCE 700

#include <stdio.h>
#include <stdlib.h>
#include <argp.h>
#include <string.h>

#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#define AS_STR2(TEXT) #TEXT
#define AS_STR(TEXT) AS_STR2(TEXT)

char *ram_array = NULL;
long ram_len = 0;

char *ram_file_name = AS_STR(RAM_FILE_NAME);
int ucode_start = 0;
int ucode_length = 0;
char *ucode_file_name = "";

const char *argp_program_version = "fpext";
const char *argp_program_bug_address = "<mschulz@seemoo.tu-darmstadt.de>";

static char doc[] = "fpext -- a program to extract flash patches form a firmware rom.";

static struct argp_option options[] = {
        {"ramfile", 'r', "FILE", 0, "Read ram from FILE"},
        {"ucodestart", 'b', "ADDR", 0, "Start address of ucode"},
        {"ucodelength", 'l', "LEN", 0, "Size of ucode in firmware"},
        {"ucodefile", 'o', "FILE", 0, "Write extracted firmware to FILE"},
        { 0 }
};

static error_t
parse_opt(int key, char *arg, struct argp_state *state)
{
        switch (key) {

                case 'r':
                        ram_file_name = arg;
                        break;

                case 'b':
                        ucode_start = strtol(arg, NULL, 0);
                        break;

                case 'l':
                        ucode_length = strtol(arg, NULL, 0);
                        break;

                case 'o':
                        ucode_file_name = arg;
                        break;
                
                default:
                        return ARGP_ERR_UNKNOWN;
        }

        return 0;
}

static struct argp argp = { options, parse_opt, 0, doc };

int
read_file_to_array(char *filename, char **buffer, long *filelen)
{
        FILE *fileptr;

        if((fileptr = fopen(filename, "rb"))) {
                fseek(fileptr, 0, SEEK_END);
                *filelen = ftell(fileptr);
                rewind(fileptr);

                *buffer = (char *) malloc(*filelen + 1);
                fread(*buffer, *filelen, 1, fileptr);
                fclose(fileptr);

                return *filelen;
        }

        return 0;
}

void
analyse_ram(FILE *fp)
{
        unsigned char *ucode = (unsigned char *) &ram_array[ucode_start];
        int i = 0;
        unsigned int a = 0;
        unsigned int b = 0;

        for (i = 0; i < ucode_length; i+=7) {
                ucode += 7;
                a = (*(ucode - 3) << 16) | (*(ucode - 4) << 24) | *(ucode - 1) | (*(ucode - 2) << 8);
                b = (*(ucode - 6) << 8) | (*(ucode - 7) << 16) | *(ucode - 5);
                fwrite(&a, sizeof(int), 1, fp);
                fwrite(&b, sizeof(int), 1, fp);
        }
}

int
main(int argc, char **argv)
{
        argp_parse(&argp, argc, argv, 0, 0, 0);

        if(!read_file_to_array(ram_file_name, &ram_array, &ram_len)) {
                fprintf(stderr, "ERR: ram file empty or unavailable.\n");
                exit(EXIT_FAILURE);
        }

        FILE *fp;

        if((fp = fopen(ucode_file_name, "wb"))) {
                analyse_ram(fp);
                fclose(fp);
        }

        exit(EXIT_SUCCESS);
}