90 lines
2.7 KiB
Go
90 lines
2.7 KiB
Go
// Copyright (c) 2016 Uber Technologies, Inc.
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package utils
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import (
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"errors"
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"net"
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)
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// This code is borrowed from https://github.com/uber/tchannel-go/blob/dev/localip.go
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// scoreAddr scores how likely the given addr is to be a remote address and returns the
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// IP to use when listening. Any address which receives a negative score should not be used.
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// Scores are calculated as:
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// -1 for any unknown IP addresses.
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// +300 for IPv4 addresses
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// +100 for non-local addresses, extra +100 for "up" interaces.
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func scoreAddr(iface net.Interface, addr net.Addr) (int, net.IP) {
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var ip net.IP
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if netAddr, ok := addr.(*net.IPNet); ok {
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ip = netAddr.IP
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} else if netIP, ok := addr.(*net.IPAddr); ok {
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ip = netIP.IP
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} else {
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return -1, nil
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}
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var score int
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if ip.To4() != nil {
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score += 300
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}
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if iface.Flags&net.FlagLoopback == 0 && !ip.IsLoopback() {
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score += 100
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if iface.Flags&net.FlagUp != 0 {
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score += 100
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}
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}
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return score, ip
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}
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// HostIP tries to find an IP that can be used by other machines to reach this machine.
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func HostIP() (net.IP, error) {
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interfaces, err := net.Interfaces()
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if err != nil {
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return nil, err
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}
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bestScore := -1
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var bestIP net.IP
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// Select the highest scoring IP as the best IP.
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for _, iface := range interfaces {
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addrs, err := iface.Addrs()
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if err != nil {
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// Skip this interface if there is an error.
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continue
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}
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for _, addr := range addrs {
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score, ip := scoreAddr(iface, addr)
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if score > bestScore {
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bestScore = score
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bestIP = ip
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}
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}
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}
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if bestScore == -1 {
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return nil, errors.New("no addresses to listen on")
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}
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return bestIP, nil
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}
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