static int monitor_route()

in bpf/xdp_router_ipv4_user.c [530:629]

• 89 lines of code
• 13 McCabe index (conditional complexity)

static int monitor_route(void)
{
	unsigned int nr_cpus = bpf_num_possible_cpus();
	const unsigned int nr_keys = 256;
	struct pollfd fds_route, fds_arp;
	__u64 prev[nr_keys][nr_cpus];
	struct sockaddr_nl la, lr;
	__u64 values[nr_cpus];
	struct nlmsghdr *nh;
	int nll, ret = 0;
	int interval = 5;
	__u32 key;
	int i;

	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (sock < 0) {
		printf("open netlink socket: %s\n", strerror(errno));
		return -1;
	}

	fcntl(sock, F_SETFL, O_NONBLOCK);
	memset(&lr, 0, sizeof(lr));
	lr.nl_family = AF_NETLINK;
	lr.nl_groups = RTMGRP_IPV6_ROUTE | RTMGRP_IPV4_ROUTE | RTMGRP_NOTIFY;
	if (bind(sock, (struct sockaddr *)&lr, sizeof(lr)) < 0) {
		printf("bind to netlink: %s\n", strerror(errno));
		ret = -1;
		goto cleanup;
	}
	fds_route.fd = sock;
	fds_route.events = POLL_IN;

	sock_arp = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
	if (sock_arp < 0) {
		printf("open netlink socket: %s\n", strerror(errno));
		return -1;
	}

	fcntl(sock_arp, F_SETFL, O_NONBLOCK);
	memset(&la, 0, sizeof(la));
	la.nl_family = AF_NETLINK;
	la.nl_groups = RTMGRP_NEIGH | RTMGRP_NOTIFY;
	if (bind(sock_arp, (struct sockaddr *)&la, sizeof(la)) < 0) {
		printf("bind to netlink: %s\n", strerror(errno));
		ret = -1;
		goto cleanup;
	}
	fds_arp.fd = sock_arp;
	fds_arp.events = POLL_IN;

	memset(prev, 0, sizeof(prev));
	do {
		signal(SIGINT, close_and_exit);
		signal(SIGTERM, close_and_exit);

		sleep(interval);
		for (key = 0; key < nr_keys; key++) {
			__u64 sum = 0;

			assert(bpf_map_lookup_elem(rxcnt_map_fd,
						   &key, values) == 0);
			for (i = 0; i < nr_cpus; i++)
				sum += (values[i] - prev[key][i]);
			if (sum)
				printf("proto %u: %10llu pkt/s\n",
				       key, sum / interval);
			memcpy(prev[key], values, sizeof(values));
		}

		memset(buf, 0, sizeof(buf));
		if (poll(&fds_route, 1, 3) == POLL_IN) {
			nll = recv_msg(lr, sock);
			if (nll < 0) {
				printf("recv from netlink: %s\n", strerror(nll));
				ret = -1;
				goto cleanup;
			}

			nh = (struct nlmsghdr *)buf;
			printf("Routing table updated.\n");
			read_route(nh, nll);
		}
		memset(buf, 0, sizeof(buf));
		if (poll(&fds_arp, 1, 3) == POLL_IN) {
			nll = recv_msg(la, sock_arp);
			if (nll < 0) {
				printf("recv from netlink: %s\n", strerror(nll));
				ret = -1;
				goto cleanup;
			}

			nh = (struct nlmsghdr *)buf;
			read_arp(nh, nll);
		}

	} while (1);
cleanup:
	close(sock);
	return ret;
}