#define _GNU_SOURCE
#include <pcap/pcap.h>
#include <error.h>
#include <stdlib.h>
#include <poll.h>
#include <errno.h>
#include <string.h>
#define error_here(status, errnum, ...) do { error_at_line(0, errnum, __FILE__, __LINE__, __VA_ARGS__); r = status; if (r) goto r; } while (0)
#define S0(x) (x ? x : "")
#define PKTSIZ 1024
int main (int argc, char ** argv) {
	struct bpf_program fp = { 0 };
	char pcaperr[PCAP_ERRBUF_SIZE];
	int r = 0;
	pcap_if_t * vmesniki = NULL;
	if (pcap_findalldevs(&vmesniki, pcaperr))
		error_here(1, 0, "pcap_findalldevs: %s", pcaperr);
	if (!vmesniki)
		error_here(2, 0, "ni vmesnikov za prisluškovanje -- zaženi airmon-ng?");
	int izbira = -1;
	if (argc > 1)
		izbira = atoi(argv[1]);
	pcap_if_t * izbran = NULL;
	int zap = 0;
	for (pcap_if_t * vmesnik = vmesniki; vmesnik; vmesnik = vmesnik->next) {
		printf("%d\t%s\t%s%s\n", zap, vmesnik->name, S0(vmesnik->description), zap == izbira ? "\tIZBRAN" : "");
		if (zap == izbira)
			izbran = vmesnik;
		zap++;
	}
	if (!izbran)
		error_here(3, 0, "v 1. argument napiši zaporedno številko vmesnika iz seznama");
	pcap_t * pcap = pcap_create(izbran->name, pcaperr);
	if (!pcap)
		error_here(4, 0, "pcap_create(NULL, pcaperr): %s", pcaperr);
	pcap_set_snaplen(pcap, PKTSIZ);
	pcap_set_promisc(pcap, 1);
	int ret = pcap_can_set_rfmon(pcap);
	if (ret < 0)
		error_here(5, 0, "pcap_can_set_rfmon(pcap): %s", pcap_geterr(pcap));
	if (ret)
		pcap_set_rfmon(pcap, 1);
	else
		error_here(0, 0, "!pcap_can_set_rfmon(pcap)");
	pcap_set_immediate_mode(pcap, 1);
	if ((ret = pcap_activate(pcap)))
		error_here(6, 0, "pcap_activate(pcap): %s", pcap_statustostr(ret));
	if (pcap_setdirection(pcap, PCAP_D_IN))
		error_here(7, 0, "pcap_setdirection(pcap, PCAP_D_IN): %s", pcap_geterr(pcap));
	if (pcap_compile(pcap, &fp, "wlan addr1 4b:40:34:41:2e:53", 1, PCAP_NETMASK_UNKNOWN))
		error_here(8, 0, "pcap_compile(pcap, fp, ...): %s", pcap_geterr(pcap));
	if (pcap_setfilter(pcap, &fp))
		error_here(9, 0, "pcap_setfilter(pcap, fp): %s", pcap_geterr(pcap));
	const unsigned char * packet = NULL;
	struct pcap_pkthdr * pkt_header = NULL;
	int fd = pcap_get_selectable_fd(pcap);
	if (fd == -1)
		error_here(10, 0, "pcap_get_selectable_fd(pcap) == -1");
	struct pollfd pollfd = {
		.fd = fd,
		.events = POLLIN
	};
	while (poll(&pollfd, 1, -1) != -1) {
		if ((ret = pcap_next_ex(pcap, &pkt_header, &packet)) == 0)
			error_here(11, 0, "pcap_next_ex(pcap, &pkt_header, &packet) == 0");
		if (ret == PCAP_ERROR)
			error_here(12, 0, "pcap_next_ex(pcap, &pkt_header, &packet): %s", pcap_geterr(pcap));
#define MAGIC "K@4A.SI "
		const unsigned char * c = memmem(packet, PKTSIZ, MAGIC, strlen(MAGIC));
		if (!c) {
			error_here(0, 0, "malformed packet");
			continue;
		}
		c += strlen(MAGIC);
		if (c + 1 /* koliko bomo brali */ >= packet+PKTSIZ) {
			error_here(0, 0, "malformed packet");
			continue;
		}
		fprintf(stderr, "\r");
		for (int i = 0; i < 128; i++)
			fprintf(stderr, i < c[0]/2 ? "@" : " ");
		fflush(stderr);
	}
	error_here(11, errno, "poll(&pollfd, 1, -1)");
	r:
	pcap_freecode(&fp);
	if (vmesniki)
		pcap_freealldevs(vmesniki);
	if (pcap)
		pcap_close(pcap);
	return r;
}