I'm doing a small program in (C / C ++) to read some data from a .CAP file (provided by TCPDUMP). A good example would be WireShark, but I need far less INFO.
It turns out, this .CAP seems to be written in HEXA and when I read the data it comes "encoded."
As I have very little experience, and I have to learn this. .. I think I'm not able to ask the question , so I count on the goodwill of my friends. p>
Not to mention that I have, I simply got lost in a sea of links on the internet, which only caused more confusion.
I explain: In this link you can download the .CAP , which is quietly opened by WireShark, since my code below returns " strange characters ".
such as:
== > revision: ò *
or
== > header_pad: ò
Where "revision", for example should be 12 HEXA or converted 18 decimal
- Well, since I'm a beginner, I tried to make the code as commented as possible.
Since this code is intended to run on a linux terminal ..
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
// #include <curses.h>
// テスト用フラグ => Test for the flag
int LOOP_ONCE = 1;
// WiFi取得情報構造体 => get information structure
// Radiotap Header
// 18bytes固定長(と思われる)=> fixed length (seems to be)
typedef struct WF_HEADER
{
char header_revision[1];
char header_pad[1];
unsigned short int header_length;
char present_flags[4];
char flags[1];
char data_rate[1];
char channel_frequency[2];
char channel_flags[2];
char ssi_signal[1];
char antenna[1];
char rx_flags[2];
} wf_header_t;
// IEEE802.11 Probe Request (前半部分)=> (first half)
// 24bytes固定長 => fixed length
typedef struct WF_PROBE1
{
char frame_control_field[4];
char receiver_address[6];
char transmitter_address[6];
char bbs_id[6];
char numbers[2];
} wf_probe1_t;
// IEEE802.11 Probe Request(後半部分)=> (the latter part)
// 4bytes固定長 => fixed length
typedef struct WF_PROBE2
{
char frame_check_sequence[4];
} wf_probe2_t;
// IEEE802.11 wireless LAN management frame(繰り返しヘッダー) => (repeat header)
// 2bytes
typedef struct WF_MANAGE_HEADER
{
char tag_number[1];
char tag_length[1];
} wf_manage_header_t;
int main(int argc, char *argv[]){
char read_fname[30]; //読み込みファイル名 => read file name
int read_fb; //読み込みファイルバンドル => read file bundle
wf_header_t *wfh; //WiFiデータ読み込み構造体のポインタ => pointer of WiFi data read structure
int read_size; //読み込みファイルサイズ => read file size
int wfh_size; // Wifiデータ構造体のサイズ => Wifi data structure; int wfh_size
/* WiFiデータ読み込み構造体の領域確保 => Area of WiFi data read structure ensure */
wfh_size = sizeof(wf_header_t);
wfh = calloc(1, wfh_size);
/* ループ実行 */
/* Loop execution */
while (1) {
/* ファイルの存在を監視する => To monitor the presence of the file */
/* 読み込みファイル名取得 => Read file name acquisition */
if (1) {
system("clear");
// テスト用プログラム => Test program
fprintf(stdout, "読み込みファイル名を入力してください。\n"); // Please enter the reading file name
scanf("%s", read_fname);
fprintf(stdout, "ファイル名:%s\n", read_fname); //file name:
} else {
// 次のファイル名を取得するような仕組み => Like to get the following file name mechanism
}
/* ファイルオープン処理 => Seek to the data top position */
read_fb = open(read_fname, O_RDONLY);
if (read_fb == -1) {
fprintf(stderr, "ファイルオープンに失敗しました。\n"); //Failed to open file
fprintf(stderr, "ファイル名:%s\n", read_fname); //file name
return -1;
}
/* データ先頭位置までシークする => Seek to the data top position * /
/* 前ファイルの続きである場合は、そのまま残サイズを読み込む => Case is a continuation of the previous file, as it is read in the remaining size */
read_size = read(read_fb, wfh, wfh_size);
if (read_size == -1) {
/* ファイル読み込み失敗 => File read failure */
free(wfh);
fprintf(stderr, "ファイル読み込みに失敗しました。\n"); //failed to file read
fprintf(stderr, "ファイル名:%s\n", read_fname); //file name
return -1;
} else if (read_size == wfh_size) {
fprintf(stdout, "====================================\n");
fprintf(stdout, "revision: %s \n", wfh->header_revision);
fprintf(stdout, "header_pad: %s \n", wfh->header_pad);
fprintf(stdout, "present_flags: %s \n", wfh->present_flags);
fprintf(stdout, "flags: %s \n", wfh->flags);
fprintf(stdout, "data_rate: %s \n", wfh->data_rate);
fprintf(stdout, "channel_frequency: %s \n", wfh->channel_frequency);
fprintf(stdout, "channel_flags: %s \n", wfh->channel_flags);
fprintf(stdout, "ssi_signal: %s \n", wfh->ssi_signal);
fprintf(stdout, "antenna: %s \n", wfh->antenna);
fprintf(stdout, "rx_flags: %s \n", wfh->rx_flags);
fprintf(stdout, "====================================\n");
} else {
/* 残りサイズを読み込み、次のファイルへ進む => Read the remaining size, advance to the next file */
}
/* 終了処理 End processing */
if (close(read_fb) != -1) {
// ファイルクローズに成功したので、バックアップフォルダへ移動させる
// Since successful file close, move to the backup folder
} else {
free(wfh);
fprintf(stderr, "ファイルクローズに失敗しました。\n"); // file close failed
fprintf(stderr, "ファイル名:%s\n", read_fname); // file name
return -1;
}
/* ループ終了判定 => Loop termination determination */
if (LOOP_ONCE == 1) {
free(wfh);
fprintf(stdout, "終了しました。\n"); // was completed
return 0;
}
}
}