feat: check port against all available hosts

README.md

@@ -64,7 +64,7 @@ Alternative ports to check. Default is `[4000, 5000, 6000, 7000]`
 
 ### `host`
 
-The host to check. Default is `process.env.HOST || '0.0.0.0'`
+The host to check. Default is `process.env.HOST` otherwise all available hosts will be checked.
 
 ### `memoDir` / `memoName`
 

src/index.ts

@@ -1,4 +1,5 @@
 import { createServer, AddressInfo } from 'net'
+import { networkInterfaces } from 'os'
 import { getMemo, setMemo } from 'fs-memo'
 
 export interface GetPortOptions {
@@ -23,7 +24,7 @@ export async function getPort (config?: GetPortInput): Promise<number> {
     random: false,
     port: parseInt(process.env.PORT || '') || 3000,
     ports: [4000, 5000, 6000, 7000],
-    host: process.env.HOST || '0.0.0.0',
+    host: undefined,
     memoName: 'port',
     ...config
   } as GetPortOptions
@@ -69,14 +70,54 @@ export async function checkPorts (ports: number[], host?: string): Promise<numbe
   return checkPort(0, host) as unknown as number
 }
 
-export function checkPort (port: number, host: string = process.env.HOST || '0.0.0.0'): Promise<number|false> {
+export type HostAddress = undefined | string
+
+export async function checkPort (port: number, host: HostAddress | HostAddress[] | undefined = process.env.HOST): Promise<number|false> {
+  if (!host) {
+    host = getLocalHosts([undefined /* default */, '0.0.0.0'])
+  }
+  if (!Array.isArray(host)) {
+    return _checkPort(port, host)
+  }
+  for (const _host of host) {
+    const _port = await _checkPort(port, _host)
+    if (_port === false) {
+      return false
+    }
+    if (port === 0 && _port !== 0) {
+      port = _port
+    }
+  }
+  return port
+}
+
+// ----- Internal -----
+
+function _checkPort (port: number, host: HostAddress): Promise<number|false> {
   return new Promise((resolve) => {
     const server = createServer()
     server.unref()
-    server.on('error', () => { resolve(false) })
-    server.listen(port, host, () => {
+    server.on('error', (err: Error & { code: string }) => {
+      // Ignore invalid host
+      if (err.code === 'EINVAL' || err.code === 'EADDRNOTAVAIL') {
+        resolve(port !== 0 ? port : false)
+      } else {
+        resolve(false)
+      }
+    })
+    server.listen({ port, host }, () => {
       const { port } = server.address() as AddressInfo
       server.close(() => { resolve(port) })
     })
   })
 }
+
+function getLocalHosts (additional?: HostAddress[]): HostAddress[] {
+  const hosts = new Set<HostAddress>(additional)
+  for (const _interface of Object.values(networkInterfaces())) {
+    for (const config of _interface!) {
+      hosts.add(config.address)
+    }
+  }
+  return Array.from(hosts)
+}

test/index.test.ts

@@ -43,3 +43,18 @@ describe('getPort (host)', () => {
     })
   })
 })
+
+describe('getPort (host)', () => {
+  let portBlocker: Server
+
+  afterEach(() => {
+    portBlocker?.close()
+  })
+
+  test('default port is in use', async () => {
+    process.env.HOST = 'localhost'
+    portBlocker = await blockPort(3000, 'localhost')
+    const port = await getPort()
+    expect(port).toEqual(4000)
+  })
+})