| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package net |
| |
| import ( |
| "fmt" |
| "net" |
| ) |
| |
| func PickTCPPort(ip string, leftPort, rightPort uint32) (uint32, error) { |
| lowestPort, highestPort := leftPort, rightPort |
| if highestPort < lowestPort { |
| lowestPort, highestPort = highestPort, lowestPort |
| } |
| // we prefer a port to remain stable over time, that's why we do sequential availability check |
| // instead of random selection |
| for port := lowestPort; port <= highestPort; port++ { |
| if actualPort, err := ReserveTCPAddr(fmt.Sprintf("%s:%d", ip, port)); err == nil { |
| return actualPort, nil |
| } |
| } |
| return 0, fmt.Errorf("unable to find port in range %d:%d", lowestPort, highestPort) |
| } |
| |
| func ReserveTCPAddr(address string) (uint32, error) { |
| addr, err := net.ResolveTCPAddr("tcp", address) |
| if err != nil { |
| return 0, err |
| } |
| l, err := net.ListenTCP("tcp", addr) |
| if err != nil { |
| return 0, err |
| } |
| defer l.Close() |
| return uint32(l.Addr().(*net.TCPAddr).Port), nil |
| } |