op-packages/luci-mod-dashboard/root/usr/share/rpcd/ucode/luci.dashboard

'use strict';

import { readfile } from 'fs';
import * as uloop from 'uloop';
import { connect } from 'ubus';

const STEP = 5000, SLOTS = 60;

let ring = [], seq = 0, timer, selectedDevice;
const bus = connect();

// Observe one main-table default-route device. Prefer IPv4, then route metric;
// keep the existing device on equal priority to avoid polling-order switches.
function sources(interfaces, previous) {
	let best = null;
	for (let iface in interfaces) {
		if (!iface.up)
			continue;
		let name = iface.device;
		if (!name || name == 'lo' || substr(name, 0, 1) == '@')
			name = iface.l3_device;
		if (!name || name == 'lo' || substr(name, 0, 1) == '@')
			continue;

		for (let route in iface.route ?? []) {
			if (+route.mask != 0)
				continue;
			const family = route.target == '0.0.0.0' ? 4 : route.target == '::' ? 6 : 0;
			if (!family)
				continue;
			// netifd omits route.table when it is inherited from the interface.
			const table = route.table ?? (family == 4 ? iface.ip4table : iface.ip6table);
			if (table && table != 254)
				continue;
			const metric = +(route.metric ?? iface.metric ?? 0);
			if (!best || family < best.family ||
			    (family == best.family && (metric < best.metric ||
			    (metric == best.metric && (name == previous ||
			    (best.device != previous && name < best.device))))))
				best = { device: name, family, metric };
		}
	}

	// Use the configured carrier (including a VLAN) without walking to its
	// physical parent, which may also carry LAN or IPTV traffic.
	return best ? [ best.device ] : [];
}

function traffic_boundary() {
	const dump = bus.call('network.interface', 'dump');
	if (type(dump?.interface) != 'array')
		return null;
	const devices = sources(dump.interface, selectedDevice);
	selectedDevice = devices[0];
	return { devices };
}

function now() {
	const c = clock(true);

	return c[0] * 1000 + int(c[1] / 1000000);
}

// Tells the instances apart, as the sequence starts over with rpcd.
const id = trim(readfile('/proc/sys/kernel/random/uuid'));

// Counters as the kernel has them. Whoever draws them takes the differences,
// over the time between two samples on the clock they were read by.
function sample() {
	const cpus = {}, net = {};
	let boundary = null;
	try { boundary = traffic_boundary(); }
	catch (e) { warn(`luci.dashboard: traffic discovery: ${e}\n`); }

	for (let line in split(readfile('/proc/stat') ?? '', '\n')) {
		if (substr(line, 0, 3) != 'cpu')
			break;

		const fields = split(line, /\s+/);

		cpus[fields[0]] = map(slice(fields, 1, 9), v => +v);
	}

	const mem = match(readfile('/proc/meminfo', 256) ?? '', /MemAvailable:\s+(\d+)/);

	// Only the selected WAN consumes network history. Check its identity
	// on both sides of the counter read to detect device recreation.
	const name = boundary?.devices?.[0];
	const before = name ? int(readfile(`/sys/class/net/${name}/ifindex`)) : null;
	const t = now();

	if (name) {
		for (let line in slice(split(readfile('/proc/net/dev') ?? '', '\n'), 2)) {
			const fields = split(trim(line), /[: ]+/);
			if (length(fields) <= 9 || fields[0] != name)
				continue;

			const after = int(readfile(`/sys/class/net/${name}/ifindex`));
			net[name] = [ +fields[1], +fields[9],
				after > 0 && after == before ? after : null ];
			break;
		}
	}

	push(ring, [ ++seq, t, cpus, mem ? +mem[1] * 1024 : null, net, boundary ]);

	while (length(ring) > SLOTS)
		shift(ring);
}

// Sampling never stops, so the charts are full whenever somebody looks.
function tick() {
	timer.set(STEP);

	// An exception here would end rpcd's uloop, not just this timer.
	try {
		sample();
	}
	catch (e) {
		warn(`luci.dashboard: ${e}\n`);
	}
}

timer = uloop.timer(0, tick);

const methods = {
	history: {
		args: { since: 0, id: 'id' },
		call: function(request) {
			const since = (request.args?.id == id) ? +(request.args?.since ?? 0) : 0;

			return {
				id,
				now: now(),
				step: STEP,
				slots: SLOTS,
				samples: filter(ring, entry => entry[0] > since)
			};
		}
	}
};

return { 'luci.dashboard': methods };