sniffer.h

/*
  ===========================================
       Copyright (c) 2017 Stefan Kremser
              github.com/spacehuhn
  ===========================================
*/


/* include all necessary libraries */ 
#include "freertos/FreeRTOS.h"
#include "esp_wifi.h"
//#include "esp_wifi_internal.h"
#include "lwip/err.h"
#include "esp_system.h"
#include "esp_event.h"
#include "esp_event_loop.h"
#include "nvs_flash.h"
#include "driver/gpio.h"

#include <Arduino.h>
#include <TimeLib.h>
#include "FS.h"
#include "PCAP.h"


//===== SETTINGS =====//
#define CHANNEL 1
#define FILENAME "raw"
#define SAVE_INTERVAL 10 //save new file every 30s
#define CHANNEL_HOPPING true //if true it will scan on all channels
#define MAX_CHANNEL 11 //(only necessary if channelHopping is true)
#define HOP_INTERVAL 214 //in ms (only necessary if channelHopping is true)


//===== Run-Time variables =====//
unsigned long lastTime = 0;
unsigned long lastChannelChange = 0;
int counter = 0;
int ch = CHANNEL;
bool fileOpen = false;

//PCAP pcap = PCAP();
PCAP pcap;
String filename = "/" + (String)FILENAME + ".pcap";

//===== FUNCTIONS =====//

bool openFile(){
  	//String filename = "capture.cap";

	
    uint32_t magic_number = 0xa1b2c3d4;
    uint16_t version_major = 2;
    uint16_t version_minor = 4;
    uint32_t thiszone = 0;
    uint32_t sigfigs = 0;
    uint32_t snaplen = 2500;
    uint32_t network = 105;

	  //if(SD.exists(filename.c_str())) removeFile(SD);
	  file = SD.open(filename, FILE_WRITE);
	  if(file) {

		filewrite_32(magic_number);
		filewrite_16(version_major);
		filewrite_16(version_minor);
		filewrite_32(thiszone);
		filewrite_32(sigfigs);
		filewrite_32(snaplen);
		filewrite_32(network);
		return true;
	  }
	  return false;
	}


/* will be executed on every packet the ESP32 gets while beeing in promiscuous mode */
void sniffer(void *buf, wifi_promiscuous_pkt_type_t type){
  
  if(fileOpen){
    wifi_promiscuous_pkt_t* pkt = (wifi_promiscuous_pkt_t*)buf;
    wifi_pkt_rx_ctrl_t ctrl = (wifi_pkt_rx_ctrl_t)pkt->rx_ctrl;
  
    uint32_t timestamp = now(); //current timestamp 
    uint32_t microseconds = (unsigned int)(micros() - millis() * 1000); //micro seconds offset (0 - 999)
    newPacketSD(timestamp, microseconds, ctrl.sig_len, pkt->payload); //write packet to file
    
  }
  
}

esp_err_t event_handler(void *ctx, system_event_t *event){ return ESP_OK; }


/* opens a new file */
void openFile2(){

  //searches for the next non-existent file name
  int c = 0;
  while(SD.open(filename)){
    filename = "/" + (String)FILENAME + "_" + (String)c + ".pcap";
    c++;
  }
  
  fileOpen = openFile();

  Serial.println("opened: "+filename);

  //reset counter (counter for saving every X seconds)
  counter = 0;
}


//===== SETUP =====//
void sniffer_setup() {
  
  Serial.begin(115200);
  //delay(2000);
  Serial.println();
  
  uint8_t cardType = SD.cardType();
  
  if(cardType == CARD_NONE){
      Serial.println("No SD card attached");
      DISP.println("NO SD CARD ATTACHED");
      return;
  }

  Serial.print("SD Card Type: ");
  if(cardType == CARD_MMC){
      Serial.println("MMC");
  } else if(cardType == CARD_SD){
      Serial.println("SDSC");
  } else if(cardType == CARD_SDHC){
      Serial.println("SDHC");
  } else {
      Serial.println("UNKNOWN");
  }

  int64_t cardSize = SD.cardSize() / (1024 * 1024);
  Serial.printf("SD Card Size: %lluMB\n", cardSize);
    
  openFile2();

  /* setup wifi */
  nvs_flash_init();
  tcpip_adapter_init();
  ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );
  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
  ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
  ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
  ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_AP) );  
  ESP_ERROR_CHECK( esp_wifi_start() );
  esp_wifi_set_promiscuous(true);
  esp_wifi_set_promiscuous_rx_cb(sniffer);
  wifi_second_chan_t secondCh = (wifi_second_chan_t)NULL;
  esp_wifi_set_channel(ch,secondCh);

  Serial.println("Sniffer started!");
 


}

void sniffer_loop() {
  unsigned long currentTime = millis();
  
  /* Channel Hopping */
  if(CHANNEL_HOPPING){
    if(currentTime - lastChannelChange >= HOP_INTERVAL){
      lastChannelChange = currentTime;
      ch++; //increase channel
      if(ch > MAX_CHANNEL) ch = 1;
      wifi_second_chan_t secondCh = (wifi_second_chan_t)NULL;
      esp_wifi_set_channel(ch,secondCh);
    }
  }

  if(fileOpen && currentTime - lastTime > 1000){
    file.flush(); //save file
    lastTime = currentTime; //update time
    counter++; //add 1 to counter
  }
  
  /* when counter > 30s interval */
  if(counter > SAVE_INTERVAL){
    //closeFile(); //save & close the file
    file.close();
    fileOpen = false; //update flag
    Serial.println("==================");
    Serial.println(filename + " saved!");
    Serial.println("==================");
    DISP.setCursor(0, 40);
    DISP.setTextColor(WHITE, BGCOLOR);
    DISP.setTextSize(TINY_TEXT);
    DISP.println("Saved to file in SD card, filename:");
    DISP.setTextSize(SMALL_TEXT);
    DISP.println(filename);
    DISP.setTextColor(FGCOLOR, BGCOLOR);
    openFile2(); //open new file
  }

}