85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
// Copyright (c) 2017 Uber Technologies, Inc.
|
|
//
|
|
// Licensed 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 utils
|
|
|
|
import (
|
|
"errors"
|
|
"net"
|
|
)
|
|
|
|
// This code is borrowed from https://github.com/uber/tchannel-go/blob/dev/localip.go
|
|
|
|
// scoreAddr scores how likely the given addr is to be a remote address and returns the
|
|
// IP to use when listening. Any address which receives a negative score should not be used.
|
|
// Scores are calculated as:
|
|
// -1 for any unknown IP addresses.
|
|
// +300 for IPv4 addresses
|
|
// +100 for non-local addresses, extra +100 for "up" interaces.
|
|
func scoreAddr(iface net.Interface, addr net.Addr) (int, net.IP) {
|
|
var ip net.IP
|
|
if netAddr, ok := addr.(*net.IPNet); ok {
|
|
ip = netAddr.IP
|
|
} else if netIP, ok := addr.(*net.IPAddr); ok {
|
|
ip = netIP.IP
|
|
} else {
|
|
return -1, nil
|
|
}
|
|
|
|
var score int
|
|
if ip.To4() != nil {
|
|
score += 300
|
|
}
|
|
if iface.Flags&net.FlagLoopback == 0 && !ip.IsLoopback() {
|
|
score += 100
|
|
if iface.Flags&net.FlagUp != 0 {
|
|
score += 100
|
|
}
|
|
}
|
|
return score, ip
|
|
}
|
|
|
|
// HostIP tries to find an IP that can be used by other machines to reach this machine.
|
|
func HostIP() (net.IP, error) {
|
|
interfaces, err := net.Interfaces()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
bestScore := -1
|
|
var bestIP net.IP
|
|
// Select the highest scoring IP as the best IP.
|
|
for _, iface := range interfaces {
|
|
addrs, err := iface.Addrs()
|
|
if err != nil {
|
|
// Skip this interface if there is an error.
|
|
continue
|
|
}
|
|
|
|
for _, addr := range addrs {
|
|
score, ip := scoreAddr(iface, addr)
|
|
if score > bestScore {
|
|
bestScore = score
|
|
bestIP = ip
|
|
}
|
|
}
|
|
}
|
|
|
|
if bestScore == -1 {
|
|
return nil, errors.New("no addresses to listen on")
|
|
}
|
|
|
|
return bestIP, nil
|
|
}
|