Create a beacon frame in userspace

userframe.c

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

#define IEEE80211_ADDR_LEN		6

#define IEEE80211_ELEMID_SSID		0
#define IEEE80211_ELEMID_RATES		1

#define	IEEE80211_FC0_TYPE_MGT		0x00
#define	IEEE80211_FC0_SUBTYPE_BEACON	0x80
#define	IEEE80211_FC1_DIR_NODS		0x00	/* STA->STA */ 

#define	IEEE80211_RATE_SIZE		8

#define SSID "NAFISA"
#define SSID_LEN 6

struct ieee80211_frame {
	uint8_t		i_fc[2];
	uint8_t		i_dur[2];
	uint8_t		i_addr1[IEEE80211_ADDR_LEN];
	uint8_t		i_addr2[IEEE80211_ADDR_LEN];
	uint8_t		i_addr3[IEEE80211_ADDR_LEN];
	uint8_t		i_seq[2];
} __packed;

#include <stdio.h>
#include <stdint.h>

void print_hex(const void *buffer, size_t length) {
    const uint8_t *buf = (const uint8_t *)buffer;

    for (size_t i = 0; i < length; i += 16) {
        printf("00%04zX: ", i);  // Print offset starting with "00"
        for (size_t j = 0; j < 16 && (i + j) < length; j++) {
            printf("%02X ", buf[i + j]);  // Print each byte in hex
        }
        printf("\n");
    }
}

int main() {
	struct ieee80211_frame *wh;
	uint8_t *frm;

	int frame_len;

	//wh = mtod(m, struct ieee80211_frame *);
	wh = malloc(100);
	memset(wh, 0, sizeof(struct ieee80211_frame));
 	wh->i_fc[0] = IEEE80211_FC0_TYPE_MGT | IEEE80211_FC0_SUBTYPE_BEACON;
 	wh->i_fc[1] = IEEE80211_FC1_DIR_NODS;

	/* Set destination, source, and BSSID to broadcast */
 	memset(wh->i_addr1, 0xff, IEEE80211_ADDR_LEN);  // Broadcast
 	memset(wh->i_addr2, 0xaa, IEEE80211_ADDR_LEN);  // Fake source MAC
 	memset(wh->i_addr3, 0xaa, IEEE80211_ADDR_LEN);  // Fake BSSID

	/* Frame body starts after the header */
	frm = (uint8_t *)(wh + 1);

	/* SSID element */
	*frm++ = IEEE80211_ELEMID_SSID;
	*frm++ = SSID_LEN;
	memcpy(frm, SSID, SSID_LEN);
	frm += SSID_LEN;

	/* Rates */
	*frm++ = IEEE80211_ELEMID_RATES;
	*frm++ = 0x8; // Size of 8
	memcpy(frm, "\x82\x84\x8b\x96\x24\x30\x48\x6c", 8);
	frm += 8;

	frame_len = frm - (uint8_t *)wh;

	printf("Frame length: %d\n", frame_len);
	print_hex(wh, frame_len);
}