src/falgnfq-dump.c


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//vim: set sw=4 ts=4 sts=4 et:
#include<inttypes.h>
#include<stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<string.h>
#include<unistd.h>

#define MAX_PATH_LEN 200


/*
 * The original purpose of this function is to dump every byte of a internet packet.
 *
 * This function will create a diretory "falgnfq-dump-dir" under current working directory,
 * and creat a dump file under "falgnfq-dump-dir" each time this function be called.
 *
 * The name of the dump file depends on the first parameter "const char* filename".
 */
int falgnfq_dump_payload(
    const char* filename,  const char* payload, uint16_t len){

    uint16_t dumped = 0;
    char dump_file_path[ strlen(filename) + 30 ];
    char dump_dir_path[] = "falgnfq-dump-dir";
    char buf[50] = {0};
    char buf_offset = 0;
    char current_byte;
    int i = 0, j = 0;

    //create a dir "falgnfq-dump-dir" under current working directory
    struct stat st = {0};
    if(stat(dump_dir_path, &st) == -1){
        mkdir(dump_dir_path, 0700);
    }

    //create a dump file under "falgnfq-dump-dir"
    sprintf(dump_file_path, "%s/%s", dump_dir_path, filename);
    FILE* fp= fopen( dump_file_path, "w" );

    for(dumped = 0; (len - dumped)/4 > 0 ; dumped += 4){
        //4 bytes in a line
        buf_offset = 0;
        for(i = 0; i < 4; i++){
            current_byte = payload[ dumped + i ];
            for(j = 7; j>=0; j--){
                buf[ buf_offset + j ] = ( (current_byte & 0x01) == 1 )? '1': '0';
                current_byte = current_byte >> 1;
            }
            if( i == 3 ){
                buf[ buf_offset + 8 ] = '\n';
                buf[ buf_offset + 9 ] = '\0';
                fputs( buf, fp );
            }else{
                //There is a space between every two bytes in the same line.
                buf[ buf_offset + 8 ] = ' ';
                buf_offset += 9;
            }
        }
    }
    if( len - dumped > 0){
        buf_offset = 0;
        for( ; len - dumped > 0; dumped++ ){
            current_byte = payload[ dumped ];
            for(j=7; j>=0; j--){
                buf[ buf_offset + j ] = ( (current_byte & 0x01) == 1 )? '1': '0';
                current_byte = current_byte >> 1;
            }
            buf[ buf_offset + 8 ] = ' ';
            buf_offset += 9;
        }
        buf[ buf_offset - 1] = '\0';
        fprintf( fp, "%s", buf );
    }

    fclose(fp);
    //return value "dumped" should equals to "len"
    return dumped;
}