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2 years ago
"use strict";
/*
* Based on the packages get-port https://www.npmjs.com/package/get-port
* and portfinder https://www.npmjs.com/package/portfinder
* The code structure is similar to get-port, but it searches
* ports deterministically like portfinder
*/
const net = require("net");
const os = require("os");
const minPort = 1024;
const maxPort = 65_535;
/**
* @return {Set<string|undefined>}
*/
const getLocalHosts = () => {
const interfaces = os.networkInterfaces();
// Add undefined value for createServer function to use default host,
// and default IPv4 host in case createServer defaults to IPv6.
// eslint-disable-next-line no-undefined
const results = new Set([undefined, "0.0.0.0"]);
for (const _interface of Object.values(interfaces)) {
if (_interface) {
for (const config of _interface) {
results.add(config.address);
}
}
}
return results;
};
/**
* @param {number} basePort
* @param {string | undefined} host
* @return {Promise<number>}
*/
const checkAvailablePort = (basePort, host) =>
new Promise((resolve, reject) => {
const server = net.createServer();
server.unref();
server.on("error", reject);
server.listen(basePort, host, () => {
// Next line should return AdressInfo because we're calling it after listen() and before close()
const { port } = /** @type {import("net").AddressInfo} */ (
server.address()
);
server.close(() => {
resolve(port);
});
});
});
/**
* @param {number} port
* @param {Set<string|undefined>} hosts
* @return {Promise<number>}
*/
const getAvailablePort = async (port, hosts) => {
/**
* Errors that mean that host is not available.
* @type {Set<string | undefined>}
*/
const nonExistentInterfaceErrors = new Set(["EADDRNOTAVAIL", "EINVAL"]);
/* Check if the post is available on every local host name */
for (const host of hosts) {
try {
await checkAvailablePort(port, host); // eslint-disable-line no-await-in-loop
} catch (error) {
/* We throw an error only if the interface exists */
if (
!nonExistentInterfaceErrors.has(
/** @type {NodeJS.ErrnoException} */ (error).code
)
) {
throw error;
}
}
}
return port;
};
/**
* @param {number} basePort
* @param {string=} host
* @return {Promise<number>}
*/
async function getPorts(basePort, host) {
if (basePort < minPort || basePort > maxPort) {
throw new Error(`Port number must lie between ${minPort} and ${maxPort}`);
}
let port = basePort;
const localhosts = getLocalHosts();
let hosts;
if (host && !localhosts.has(host)) {
hosts = new Set([host]);
} else {
/* If the host is equivalent to localhost
we need to check every equivalent host
else the port might falsely appear as available
on some operating systems */
hosts = localhosts;
}
/** @type {Set<string | undefined>} */
const portUnavailableErrors = new Set(["EADDRINUSE", "EACCES"]);
while (port <= maxPort) {
try {
const availablePort = await getAvailablePort(port, hosts); // eslint-disable-line no-await-in-loop
return availablePort;
} catch (error) {
/* Try next port if port is busy; throw for any other error */
if (
!portUnavailableErrors.has(
/** @type {NodeJS.ErrnoException} */ (error).code
)
) {
throw error;
}
port += 1;
}
}
throw new Error("No available ports found");
}
module.exports = getPorts;