"use strict";
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const execa = require("execa");
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const os = require("os");
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const net = require("net");
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const gwArgs = "path Win32_NetworkAdapterConfiguration where IPEnabled=true get DefaultIPGateway,GatewayCostMetric,IPConnectionMetric,Index /format:table".split(" ");
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const ifArgs = index => `path Win32_NetworkAdapter where Index=${index} get NetConnectionID,MACAddress /format:table`.split(" ");
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const spawnOpts = {
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windowsHide: true,
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};
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// Parsing tables like this. The final metric is GatewayCostMetric + IPConnectionMetric
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//
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// DefaultIPGateway GatewayCostMetric Index IPConnectionMetric
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// {"1.2.3.4", "2001:db8::1"} {0, 256} 12 25
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// {"2.3.4.5"} {25} 12 55
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function parseGwTable(gwTable, family) {
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let [bestGw, bestMetric, bestId] = [null, null, null];
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for (let line of (gwTable || "").trim().split(/\r?\n/).splice(1)) {
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line = line.trim();
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const [_, gwArr, gwCostsArr, id, ipMetric] = /({.+?}) +?({.+?}) +?([0-9]+) +?([0-9]+)/g.exec(line) || [];
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if (!gwArr) continue;
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const gateways = (gwArr.match(/"(.+?)"/g) || []).map(match => match.substring(1, match.length - 1));
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const gatewayCosts = (gwCostsArr.match(/[0-9]+/g) || []);
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for (const [index, gateway] of Object.entries(gateways)) {
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if (!gateway || `v${net.isIP(gateway)}` !== family) continue;
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const metric = parseInt(gatewayCosts[index]) + parseInt(ipMetric);
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if (!bestGw || metric < bestMetric) {
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[bestGw, bestMetric, bestId] = [gateway, metric, id];
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}
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}
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}
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if (bestGw) return [bestGw, bestId];
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}
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function parseIfTable(ifTable) {
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const line = (ifTable || "").trim().split("\n")[1];
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let [mac, name] = line.trim().split(/\s+/);
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mac = mac.toLowerCase();
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// try to get the interface name by matching the mac to os.networkInterfaces to avoid wmic's encoding issues
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// https://github.com/silverwind/default-gateway/issues/14
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for (const [osname, addrs] of Object.entries(os.networkInterfaces())) {
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for (const addr of addrs) {
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if (addr && addr.mac && addr.mac.toLowerCase() === mac) {
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return osname;
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}
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}
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}
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return name;
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}
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const promise = async family => {
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const {stdout} = await execa("wmic", gwArgs, spawnOpts);
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const [gateway, id] = parseGwTable(stdout, family) || [];
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if (!gateway) {
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throw new Error("Unable to determine default gateway");
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}
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let name;
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if (id) {
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const {stdout} = await execa("wmic", ifArgs(id), spawnOpts);
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name = parseIfTable(stdout);
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}
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return {gateway, interface: name ? name : null};
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};
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const sync = family => {
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const {stdout} = execa.sync("wmic", gwArgs, spawnOpts);
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const [gateway, id] = parseGwTable(stdout, family) || [];
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if (!gateway) {
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throw new Error("Unable to determine default gateway");
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}
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let name;
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if (id) {
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const {stdout} = execa.sync("wmic", ifArgs(id), spawnOpts);
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name = parseIfTable(stdout);
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}
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return {gateway, interface: name ? name : null};
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};
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module.exports.v4 = () => promise("v4");
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module.exports.v6 = () => promise("v6");
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module.exports.v4.sync = () => sync("v4");
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module.exports.v6.sync = () => sync("v6");
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