/*
 * A generic packet generator application.
 *
 * Copyright Richard Sharpe, 2019.
 *
 * You are welcome to use, modify, otherwise, this code.
 *
 * You will need libpcap installed.
 *
 * Create a Makefile with this:
 * 
 * all:
 *	cc -g -o pkt-gen pkt-gen.c -I . -lpcap
 *
 */

#include <errno.h>
#include <pcap/pcap.h>
#include <stdlib.h>
#include <string.h>

struct s1g_radiotap_hdr {
	uint16_t type;
	uint16_t len;
	uint16_t known;
	uint16_t data1;
	uint16_t data2;
	uint8_t ndp_type;
	uint8_t ndp_data[5];
} __attribute__((packed));

struct radiotap_hdr {
	uint8_t vers;
	uint8_t pad;
	uint16_t len;
	uint32_t presence_flags;
	uint32_t MAC_timestamp[2];
	uint8_t flags;
	uint8_t data_rate;
	uint16_t pad2;
	struct s1g_radiotap_hdr s1g_hdr;
} __attribute__((packed));

struct complete_pkt {
	struct radiotap_hdr radiotap;
	uint8_t pkt_data[26];
} __attribute__((packed));

uint8_t pkt_data[26] = { 0x1c, 0x0b, 0x00, 0x00, 0x02, 0x00, 0xeb, 0x4b,
			 0x02, 0x8b, 0x12, 0x52, 0xa7, 0x6b, 0x00, 0x62,
			 0x9c, 0x6b, 0x64, 0x4e, 0x35, 0xae, 0x05, 0x02,
			 0x00, 0x02 };

int main(int argc, char *argv[])
{
	int err = -1;
	pcap_t *pd = NULL;
	void *ctx = NULL;
	struct pcap_pkthdr hdr;
	struct timeval ts;
	pcap_dumper_t *dumper = NULL;
	struct complete_pkt pkt;

	if (argc < 2) {
		printf("Usage: %s <pcap-file-name>\n", argv[0]);
		return 1;
	}

	pd = pcap_open_dead(DLT_IEEE802_11_RADIO, 65535);
	if (pd == NULL) {
		fprintf(stderr, "Unable to open pcap device: %s\n",
			strerror(errno));
		return -1;
	}

	dumper = pcap_dump_open(pd, argv[1]);
        if (dumper == NULL) {
		fprintf(stderr, "Unable to create dump file %s: %s\n",
			argv[1], pcap_geterr(pd));
		goto close_pd;
	}

	/*
	 * Now create the comlete packet.
	 */
	pkt.radiotap.vers = 0;
	pkt.radiotap.pad = 0;
	pkt.radiotap.len = sizeof(struct radiotap_hdr);
	pkt.radiotap.presence_flags = 0x10000007;
	pkt.radiotap.MAC_timestamp[0] = 0x17860500;
	pkt.radiotap.MAC_timestamp[1] = 0x22ac9b1a;
	pkt.radiotap.flags = 0;
	pkt.radiotap.data_rate = 0x0c;
	pkt.radiotap.pad2 = 0xffff;
	pkt.radiotap.s1g_hdr.type = 32;
	pkt.radiotap.s1g_hdr.len = 12;
	pkt.radiotap.s1g_hdr.known = 0x0005; /* S1G PPDU forman and GU known */
	pkt.radiotap.s1g_hdr.data1 = 0x0020;
	pkt.radiotap.s1g_hdr.data2 = 0x0;
	pkt.radiotap.s1g_hdr.ndp_type = 0;
	pkt.radiotap.s1g_hdr.ndp_data[0] = 0;
	pkt.radiotap.s1g_hdr.ndp_data[1] = 0;
	pkt.radiotap.s1g_hdr.ndp_data[2] = 0;
	pkt.radiotap.s1g_hdr.ndp_data[3] = 0;
	pkt.radiotap.s1g_hdr.ndp_data[4] = 0;
	memcpy(pkt.pkt_data, pkt_data, sizeof(pkt.pkt_data));

	gettimeofday(&ts, NULL);
	hdr.ts = ts;
	hdr.caplen = sizeof(struct complete_pkt);
	hdr.len = sizeof(struct complete_pkt);

	pcap_dump((u_char *)dumper, &hdr, (u_char *)&pkt);

	/* Dump another with different values */
	pkt.radiotap.s1g_hdr.known = 0x0035;
	pkt.radiotap.s1g_hdr.data1 = 0xB421;

	pcap_dump((u_char *)dumper, &hdr, (u_char *)&pkt);

	pkt.radiotap.s1g_hdr.known = 0x0180;
	pkt.radiotap.s1g_hdr.data1 = 0;
	pkt.radiotap.s1g_hdr.ndp_type = 0;
	pkt.radiotap.s1g_hdr.ndp_data[0] = 0xe2;
	pkt.radiotap.s1g_hdr.ndp_data[1] = 0xd9;
	pkt.radiotap.s1g_hdr.ndp_data[2] = 0x03;
	pkt.radiotap.s1g_hdr.ndp_data[3] = 0x00;
	pkt.radiotap.s1g_hdr.ndp_data[4] = 0x80;

	hdr.caplen = sizeof(struct radiotap_hdr);
	hdr.len = sizeof(struct radiotap_hdr);

	pcap_dump((u_char *)dumper, &hdr, (u_char *)&pkt);

close_dumper:
	pcap_dump_close(dumper);
close_pd:
	pcap_close(pd);
	return err;
}