mirror of
https://github.com/etcd-io/etcd.git
synced 2024-09-27 06:25:44 +00:00
134 lines
2.9 KiB
Go
134 lines
2.9 KiB
Go
// Copyright 2016 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build linux
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// +build 386 amd64
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// TODO support native endian but without using "unsafe"
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package netutil
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"net"
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"syscall"
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)
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var errNoDefaultRoute = fmt.Errorf("could not find default route")
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func GetDefaultHost() (string, error) {
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rmsg, rerr := getDefaultRoute()
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if rerr != nil {
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return "", rerr
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}
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attrs, aerr := syscall.ParseNetlinkRouteAttr(rmsg)
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if aerr != nil {
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return "", aerr
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}
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oif := uint32(0)
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for _, attr := range attrs {
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if attr.Attr.Type == syscall.RTA_PREFSRC {
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return net.IP(attr.Value).String(), nil
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}
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if attr.Attr.Type == syscall.RTA_OIF {
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oif = binary.LittleEndian.Uint32(attr.Value)
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}
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}
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if oif == 0 {
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return "", errNoDefaultRoute
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}
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// prefsrc not detected, fall back to getting address from iface
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ifmsg, ierr := getIface(oif)
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if ierr != nil {
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return "", ierr
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}
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attrs, aerr = syscall.ParseNetlinkRouteAttr(ifmsg)
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if aerr != nil {
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return "", aerr
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}
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for _, attr := range attrs {
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if attr.Attr.Type == syscall.RTA_SRC {
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return net.IP(attr.Value).String(), nil
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}
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}
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return "", errNoDefaultRoute
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}
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func getDefaultRoute() (*syscall.NetlinkMessage, error) {
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dat, err := syscall.NetlinkRIB(syscall.RTM_GETROUTE, syscall.AF_UNSPEC)
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if err != nil {
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return nil, err
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}
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msgs, msgErr := syscall.ParseNetlinkMessage(dat)
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if msgErr != nil {
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return nil, msgErr
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}
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rtmsg := syscall.RtMsg{}
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for _, m := range msgs {
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if m.Header.Type != syscall.RTM_NEWROUTE {
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continue
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}
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buf := bytes.NewBuffer(m.Data[:syscall.SizeofRtMsg])
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if rerr := binary.Read(buf, binary.LittleEndian, &rtmsg); rerr != nil {
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continue
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}
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if rtmsg.Dst_len == 0 {
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// zero-length Dst_len implies default route
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return &m, nil
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}
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}
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return nil, errNoDefaultRoute
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}
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func getIface(idx uint32) (*syscall.NetlinkMessage, error) {
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dat, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
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if err != nil {
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return nil, err
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}
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msgs, msgErr := syscall.ParseNetlinkMessage(dat)
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if msgErr != nil {
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return nil, msgErr
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}
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ifaddrmsg := syscall.IfAddrmsg{}
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for _, m := range msgs {
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if m.Header.Type != syscall.RTM_NEWADDR {
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continue
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}
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buf := bytes.NewBuffer(m.Data[:syscall.SizeofIfAddrmsg])
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if rerr := binary.Read(buf, binary.LittleEndian, &ifaddrmsg); rerr != nil {
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continue
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}
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if ifaddrmsg.Index == idx {
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return &m, nil
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}
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}
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return nil, errNoDefaultRoute
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}
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