int main()

in bpf/xdp_tx_iptunnel_user.c [153:308]
136 lines of code
37 McCabe index (conditional complexity)

int main(int argc, char **argv)
{
	struct bpf_prog_load_attr prog_load_attr = {
		.prog_type	= BPF_PROG_TYPE_XDP,
	};
	int min_port = 0, max_port = 0, vip2tnl_map_fd;
	const char *optstr = "i:a:p:s:d:m:T:P:FSNh";
	unsigned char opt_flags[256] = {};
	struct bpf_prog_info info = {};
	__u32 info_len = sizeof(info);
	unsigned int kill_after_s = 0;
	struct iptnl_info tnl = {};
	struct bpf_object *obj;
	struct vip vip = {};
	char filename[256];
	int opt, prog_fd;
	int i, err;

	tnl.family = AF_UNSPEC;
	vip.protocol = IPPROTO_TCP;

	for (i = 0; i < strlen(optstr); i++)
		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
			opt_flags[(unsigned char)optstr[i]] = 1;

	while ((opt = getopt(argc, argv, optstr)) != -1) {
		unsigned short family;
		unsigned int *v6;

		switch (opt) {
		case 'i':
			ifindex = if_nametoindex(optarg);
			if (!ifindex)
				ifindex = atoi(optarg);
			break;
		case 'a':
			vip.family = parse_ipstr(optarg, vip.daddr.v6);
			if (vip.family == AF_UNSPEC)
				return 1;
			break;
		case 'p':
			if (parse_ports(optarg, &min_port, &max_port))
				return 1;
			break;
		case 'P':
			vip.protocol = atoi(optarg);
			break;
		case 's':
		case 'd':
			if (opt == 's')
				v6 = tnl.saddr.v6;
			else
				v6 = tnl.daddr.v6;

			family = parse_ipstr(optarg, v6);
			if (family == AF_UNSPEC)
				return 1;
			if (tnl.family == AF_UNSPEC) {
				tnl.family = family;
			} else if (tnl.family != family) {
				fprintf(stderr,
					"The IP version of the src and dst addresses used in the IP encapsulation does not match\n");
				return 1;
			}
			break;
		case 'm':
			if (!ether_aton_r(optarg,
					  (struct ether_addr *)tnl.dmac)) {
				fprintf(stderr, "Invalid mac address:%s\n",
					optarg);
				return 1;
			}
			break;
		case 'T':
			kill_after_s = atoi(optarg);
			break;
		case 'S':
			xdp_flags |= XDP_FLAGS_SKB_MODE;
			break;
		case 'N':
			/* default, set below */
			break;
		case 'F':
			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
			break;
		default:
			usage(argv[0]);
			return 1;
		}
		opt_flags[opt] = 0;
	}

	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
		xdp_flags |= XDP_FLAGS_DRV_MODE;

	for (i = 0; i < strlen(optstr); i++) {
		if (opt_flags[(unsigned int)optstr[i]]) {
			fprintf(stderr, "Missing argument -%c\n", optstr[i]);
			usage(argv[0]);
			return 1;
		}
	}

	if (!ifindex) {
		fprintf(stderr, "Invalid ifname\n");
		return 1;
	}

	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
	prog_load_attr.file = filename;

	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
		return 1;

	if (!prog_fd) {
		printf("bpf_prog_load_xattr: %s\n", strerror(errno));
		return 1;
	}

	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
	vip2tnl_map_fd = bpf_object__find_map_fd_by_name(obj, "vip2tnl");
	if (vip2tnl_map_fd < 0 || rxcnt_map_fd < 0) {
		printf("bpf_object__find_map_fd_by_name failed\n");
		return 1;
	}

	signal(SIGINT, int_exit);
	signal(SIGTERM, int_exit);

	while (min_port <= max_port) {
		vip.dport = htons(min_port++);
		if (bpf_map_update_elem(vip2tnl_map_fd, &vip, &tnl,
					BPF_NOEXIST)) {
			perror("bpf_map_update_elem(&vip2tnl)");
			return 1;
		}
	}

	if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
		printf("link set xdp fd failed\n");
		return 1;
	}

	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
	if (err) {
		printf("can't get prog info - %s\n", strerror(errno));
		return err;
	}
	prog_id = info.id;

	poll_stats(kill_after_s);

	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);

	return 0;
}