ESP32 raw packets

ESP32_raw_packet.ino

#include <WiFi.h>
#include "wifi_headers.h"
#include <esp_wifi.h>
//#include <esp_wifi_internal.h>
#include <lwip/err.h>

typedef union {
     uint8_t fix_rate;
     uint8_t b5;
     uint8_t b4;
 
     struct {
         uint8_t b3;
         uint8_t b2;
     } b1;
 
     struct {
         uint32_t a1;
         uint8_t  a2;
         uint8_t  a3;
         uint8_t  a4;
         uint8_t  a5;
         struct {
             uint8_t a6;
             uint8_t a7;
         } a8[4];
         uint8_t a9;
         uint8_t a10;
         uint8_t a11;
         uint8_t a12;
     } a13;
 
 } wifi_internal_rate_t;

 #define RATE_MCS4_SP 28 // N 43.3Mb MCS4 SP

// buffer: Raw IEEE 802.11 packet to send
// len: Length of IEEE 802.11 packet
// en_sys_seq: see https://github.com/espressif/esp-idf/blob/master/docs/api-guides/wifi.rst#wi-fi-80211-packet-send for details
extern "C" {
  esp_err_t esp_wifi_80211_tx(wifi_interface_t ifx, const void *buffer, int len, bool en_sys_seq);
  esp_err_t esp_wifi_internal_set_rate(int a, int b, int c, wifi_internal_rate_t *d);
}

mac_t BCAST(true);
mac_t ME;

void setup() {
  Serial.begin(115200);
  Serial.println("Start");
  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
  esp_wifi_init(&cfg);
  esp_wifi_set_mode(WIFI_MODE_NULL);
  wifi_internal_rate_t rate;
  rate.fix_rate = RATE_MCS4_SP;
  esp_wifi_internal_set_rate(100, 1, 4, &rate);
  esp_wifi_start();
  esp_wifi_set_ps(WIFI_PS_NONE);
  
  Serial.println("Done setup");
  WiFi.macAddress(ME.mac);
}

void loop() {
  byte data[sizeof(WiFiHeader) + 20];
  WiFiHeader* pkt = (WiFiHeader*)data;
  pkt->frame_control.type = WIFI_TYPE_DATA;
  pkt->frame_control.subtype = 0;
  pkt->frame_control.to_ds = 1;
  pkt->address_1 = BCAST;
  pkt->address_2 = ME;
  pkt->address_3 = ME;

  memset(data + sizeof(WiFiHeader), 40, 20);
  
  int result = esp_wifi_80211_tx(WIFI_IF_AP, data, sizeof(data), true);
  switch (result) {
    case ERR_OK: Serial.println("ERR_OK"); break;
    case ERR_MEM: Serial.println("ERR_MEM"); break;
    case ERR_IF: Serial.println("ERR_IF"); break;
    case ERR_ARG: Serial.println("ERR_ARG"); break;
    default: Serial.println(result);
  }
  delay(1000);
}