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Merge pull request #45642 from JiangtianLi/jiangtli-fixdns2

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Automatic merge from submit-queue

Fix the issue in Windows kube-proxy when processing unqualified name. This is for DNS client such as ping or iwr that validate name in response and original question.

**What this PR does / why we need it**:
This PR is an additional fix to #41618 and [the corresponding commit](b9dfb69dd7). The DNS client such as nslookup does not validate name matching in response and original question. That works fine when we append DNS suffix to unqualified name in DNS query in Windows kube-proxy. However, for DNS client such as ping or Invoke-WebRequest that validates name in response and original question, the issue arises and the DNS query fails although the received DNS response has no error. 

This PR fixes the additional issue by restoring the original question name in DNS response. Further, this PR refactors DNS message routines by using miekg's DNS library.

This PR affects the Windows kube-proxy only.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #42605 

**Special notes for your reviewer**:

**Release note**:

```release-note
Fix DNS suffix search list support in Windows kube-proxy.
```
This commit is contained in:
Kubernetes Submit Queue
2017-05-17 23:48:27 -07:00
committed by GitHub
parent e7b1814863 1760767047
commit f706b81007
4 changed files with 140 additions and 382 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
pkg/proxy/winuserspace/BUILD
View File

@@ -28,6 +28,7 @@ go_library(
"//pkg/util/netsh:go_default_library",
"//pkg/util/slice:go_default_library",
"//vendor/github.com/golang/glog:go_default_library",
"//vendor/github.com/miekg/dns:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/util/net:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
@@ -38,7 +39,6 @@ go_test(
name = "go_default_test",
srcs = [
"proxier_test.go",
"proxysocket_test.go",
"roundrobin_test.go",
],
library = ":go_default_library",

2
pkg/proxy/winuserspace/proxier.go
View File

@@ -262,7 +262,7 @@ func (proxier *Proxier) addServicePortPortal(servicePortPortalName ServicePortPo
socket: sock,
timeout: timeout,
activeClients: newClientCache(),
dnsClients: newDnsClientCache(),
dnsClients: newDNSClientCache(),
sessionAffinityType: api.ServiceAffinityNone, // default
}
proxier.setServiceInfo(servicePortPortalName, si)

389
pkg/proxy/winuserspace/proxysocket.go
View File

@@ -17,7 +17,6 @@ limitations under the License.
package winuserspace
import (
"encoding/binary"
"fmt"
"io"
"net"
@@ -28,6 +27,7 @@ import (
"time"
"github.com/golang/glog"
"github.com/miekg/dns"
"k8s.io/apimachinery/pkg/types"
"k8s.io/apimachinery/pkg/util/runtime"
"k8s.io/kubernetes/pkg/api"
@@ -237,190 +237,6 @@ func newClientCache() *clientCache {
return &clientCache{clients: map[string]net.Conn{}}
}
// TODO: use Go net dnsmsg library to walk DNS message format
// DNS packet header
type dnsHeader struct {
id uint16
bits uint16
qdCount uint16
anCount uint16
nsCount uint16
arCount uint16
}
// DNS domain name
type dnsDomainName struct {
name string
}
// DNS packet question section
type dnsQuestion struct {
qName dnsDomainName
qType uint16
qClass uint16
}
// DNS message, only interested in question now
type dnsMsg struct {
header dnsHeader
question []dnsQuestion
}
type dnsStruct interface {
walk(f func(field interface{}) (ok bool)) (ok bool)
}
func (header *dnsHeader) walk(f func(field interface{}) bool) bool {
return f(&header.id) &&
f(&header.bits) &&
f(&header.qdCount) &&
f(&header.anCount) &&
f(&header.nsCount) &&
f(&header.arCount)
}
func (question *dnsQuestion) walk(f func(field interface{}) bool) bool {
return f(&question.qName) &&
f(&question.qType) &&
f(&question.qClass)
}
func packDomainName(name string, buffer []byte, index int) (newIndex int, ok bool) {
if name == "" {
buffer[index] = 0
index++
return index, true
}
// one more dot plus trailing 0
if index+len(name)+2 > len(buffer) {
return len(buffer), false
}
domains := strings.Split(name, ".")
for _, domain := range domains {
domainLen := len(domain)
if domainLen == 0 {
return len(buffer), false
}
buffer[index] = byte(domainLen)
index++
copy(buffer[index:index+domainLen], domain)
index += domainLen
}
buffer[index] = 0
index++
return index, true
}
func unpackDomainName(buffer []byte, index int) (name string, newIndex int, ok bool) {
name = ""
for index < len(buffer) {
cnt := int(buffer[index])
index++
if cnt == 0 {
break
}
if index+cnt > len(buffer) {
return "", len(buffer), false
}
if name != "" {
name += "."
}
name += string(buffer[index : index+cnt])
index += cnt
}
if index >= len(buffer) {
return "", len(buffer), false
}
return name, index, true
}
func packStruct(any dnsStruct, buffer []byte, index int) (newIndex int, ok bool) {
ok = any.walk(func(field interface{}) bool {
switch value := field.(type) {
case *uint16:
if index+2 > len(buffer) {
return false
}
binary.BigEndian.PutUint16(buffer[index:index+2], *value)
index += 2
return true
case *dnsDomainName:
index, ok = packDomainName((*value).name, buffer, index)
return ok
default:
return false
}
})
if !ok {
return len(buffer), false
}
return index, true
}
func unpackStruct(any dnsStruct, buffer []byte, index int) (newIndex int, ok bool) {
ok = any.walk(func(field interface{}) bool {
switch value := field.(type) {
case *uint16:
if index+2 > len(buffer) {
return false
}
*value = binary.BigEndian.Uint16(buffer[index : index+2])
index += 2
return true
case *dnsDomainName:
(*value).name, index, ok = unpackDomainName(buffer, index)
return ok
default:
return false
}
})
if !ok {
return len(buffer), false
}
return index, true
}
// Pack the message structure into buffer
func (msg *dnsMsg) packDnsMsg(buffer []byte) (length int, ok bool) {
index := 0
if index, ok = packStruct(&msg.header, buffer, index); !ok {
return len(buffer), false
}
for i := 0; i < len(msg.question); i++ {
if index, ok = packStruct(&msg.question[i], buffer, index); !ok {
return len(buffer), false
}
}
return index, true
}
// Unpack the buffer into the message structure
func (msg *dnsMsg) unpackDnsMsg(buffer []byte) (ok bool) {
index := 0
if index, ok = unpackStruct(&msg.header, buffer, index); !ok {
return false
}
msg.question = make([]dnsQuestion, msg.header.qdCount)
for i := 0; i < len(msg.question); i++ {
if index, ok = unpackStruct(&msg.question[i], buffer, index); !ok {
return false
}
}
return true
}
// DNS query client classified by address and QTYPE
type dnsClientQuery struct {
clientAddress string
@@ -436,44 +252,81 @@ type dnsClientCache struct {
type dnsQueryState struct {
searchIndex int32
msg *dnsMsg
msg *dns.Msg
}
func newDnsClientCache() *dnsClientCache {
func newDNSClientCache() *dnsClientCache {
return &dnsClientCache{clients: map[dnsClientQuery]*dnsQueryState{}}
}
func packetRequiresDnsSuffix(dnsType, dnsClass uint16) bool {
func packetRequiresDNSSuffix(dnsType, dnsClass uint16) bool {
return (dnsType == dnsTypeA || dnsType == dnsTypeAAAA) && dnsClass == dnsClassInternet
}
func isDnsService(portName string) bool {
func isDNSService(portName string) bool {
return portName == dnsPortName
}
func appendDnsSuffix(msg *dnsMsg, buffer []byte, length int, dnsSuffix string) int {
if msg == nil || len(msg.question) == 0 {
glog.Warning("DNS message parameter is invalid.")
return length
func appendDNSSuffix(msg *dns.Msg, buffer []byte, length int, dnsSuffix string) (int, error) {
if msg == nil || len(msg.Question) == 0 {
return length, fmt.Errorf("DNS message parameter is invalid")
}
// Save the original name since it will be reused for next iteration
origName := msg.question[0].qName.name
origName := msg.Question[0].Name
if dnsSuffix != "" {
msg.question[0].qName.name += "." + dnsSuffix
msg.Question[0].Name += dnsSuffix + "."
}
len, ok := msg.packDnsMsg(buffer)
msg.question[0].qName.name = origName
mbuf, err := msg.PackBuffer(buffer)
msg.Question[0].Name = origName
if !ok {
glog.Warning("Unable to pack DNS packet.")
return length
if err != nil {
glog.Warning("Unable to pack DNS packet. Error is: %v", err)
return length, err
}
return len
if &buffer[0] != &mbuf[0] {
return length, fmt.Errorf("Buffer is too small in packing DNS packet")
}
return len(mbuf), nil
}
func processUnpackedDnsQueryPacket(dnsClients *dnsClientCache, msg *dnsMsg, host string, dnsQType uint16, buffer []byte, length int, dnsSearch []string) int {
func recoverDNSQuestion(origName string, msg *dns.Msg, buffer []byte, length int) (int, error) {
if msg == nil || len(msg.Question) == 0 {
return length, fmt.Errorf("DNS message parameter is invalid")
}
if origName == msg.Question[0].Name {
return length, nil
}
msg.Question[0].Name = origName
if len(msg.Answer) > 0 {
msg.Answer[0].Header().Name = origName
}
mbuf, err := msg.PackBuffer(buffer)
if err != nil {
glog.Warning("Unable to pack DNS packet. Error is: %v", err)
return length, err
}
if &buffer[0] != &mbuf[0] {
return length, fmt.Errorf("Buffer is too small in packing DNS packet")
}
return len(mbuf), nil
}
func processUnpackedDNSQueryPacket(
dnsClients *dnsClientCache,
msg *dns.Msg,
host string,
dnsQType uint16,
buffer []byte,
length int,
dnsSearch []string) int {
if dnsSearch == nil || len(dnsSearch) == 0 {
glog.V(1).Infof("DNS search list is not initialized and is empty.")
return length
@@ -490,22 +343,36 @@ func processUnpackedDnsQueryPacket(dnsClients *dnsClientCache, msg *dnsMsg, host
index := atomic.SwapInt32(&state.searchIndex, state.searchIndex+1)
// Also update message ID if the client retries due to previous query time out
state.msg.header.id = msg.header.id
state.msg.MsgHdr.Id = msg.MsgHdr.Id
if index < 0 || index >= int32(len(dnsSearch)) {
glog.V(1).Infof("Search index %d is out of range.", index)
return length
}
length = appendDnsSuffix(msg, buffer, length, dnsSearch[index])
length, err := appendDNSSuffix(msg, buffer, length, dnsSearch[index])
if err != nil {
glog.Errorf("Append DNS suffix failed: %v", err)
}
return length
}
func processUnpackedDnsResponsePacket(svrConn net.Conn, dnsClients *dnsClientCache, rcode uint16, host string, dnsQType uint16, buffer []byte, length int, dnsSearch []string) bool {
func processUnpackedDNSResponsePacket(
svrConn net.Conn,
dnsClients *dnsClientCache,
msg *dns.Msg,
rcode int,
host string,
dnsQType uint16,
buffer []byte,
length int,
dnsSearch []string) (bool, int) {
var drop bool
var err error
if dnsSearch == nil || len(dnsSearch) == 0 {
glog.V(1).Infof("DNS search list is not initialized and is empty.")
return drop
return drop, length
}
dnsClients.mu.Lock()
@@ -518,107 +385,121 @@ func processUnpackedDnsResponsePacket(svrConn net.Conn, dnsClients *dnsClientCac
// If the reponse has failure and iteration through the search list has not
// reached the end, retry on behalf of the client using the original query message
drop = true
length = appendDnsSuffix(state.msg, buffer, length, dnsSearch[index])
length, err = appendDNSSuffix(state.msg, buffer, length, dnsSearch[index])
if err != nil {
glog.Errorf("Append DNS suffix failed: %v", err)
}
_, err := svrConn.Write(buffer[0:length])
_, err = svrConn.Write(buffer[0:length])
if err != nil {
if !logTimeout(err) {
glog.Errorf("Write failed: %v", err)
}
}
} else {
length, err = recoverDNSQuestion(state.msg.Question[0].Name, msg, buffer, length)
if err != nil {
glog.Errorf("Recover DNS question failed: %v", err)
}
dnsClients.mu.Lock()
delete(dnsClients.clients, dnsClientQuery{host, dnsQType})
dnsClients.mu.Unlock()
}
}
return drop
return drop, length
}
func processDnsQueryPacket(dnsClients *dnsClientCache, cliAddr net.Addr, buffer []byte, length int, dnsSearch []string) int {
msg := &dnsMsg{}
if !msg.unpackDnsMsg(buffer[:length]) {
glog.Warning("Unable to unpack DNS packet.")
return length
func processDNSQueryPacket(
dnsClients *dnsClientCache,
cliAddr net.Addr,
buffer []byte,
length int,
dnsSearch []string) (int, error) {
msg := &dns.Msg{}
if err := msg.Unpack(buffer[:length]); err != nil {
glog.Warning("Unable to unpack DNS packet. Error is: %v", err)
return length, err
}
// Query - Response bit that specifies whether this message is a query (0) or a response (1).
qr := msg.header.bits & 0x8000
if qr != 0 {
glog.Warning("DNS packet should be a query message.")
return length
if msg.MsgHdr.Response == true {
return length, fmt.Errorf("DNS packet should be a query message")
}
// QDCOUNT
if msg.header.qdCount != 1 {
glog.V(1).Infof("Number of entries in the question section of the DNS packet is: %d", msg.header.qdCount)
if len(msg.Question) != 1 {
glog.V(1).Infof("Number of entries in the question section of the DNS packet is: %d", len(msg.Question))
glog.V(1).Infof("DNS suffix appending does not support more than one question.")
return length
return length, nil
}
// ANCOUNT, NSCOUNT, ARCOUNT
if msg.header.anCount != 0 || msg.header.nsCount != 0 || msg.header.arCount != 0 {
if len(msg.Answer) != 0 || len(msg.Ns) != 0 || len(msg.Extra) != 0 {
glog.V(1).Infof("DNS packet contains more than question section.")
return length
return length, nil
}
dnsQType := msg.question[0].qType
dnsQClass := msg.question[0].qClass
if packetRequiresDnsSuffix(dnsQType, dnsQClass) {
dnsQType := msg.Question[0].Qtype
dnsQClass := msg.Question[0].Qclass
if packetRequiresDNSSuffix(dnsQType, dnsQClass) {
host, _, err := net.SplitHostPort(cliAddr.String())
if err != nil {
glog.V(1).Infof("Failed to get host from client address: %v", err)
host = cliAddr.String()
}
length = processUnpackedDnsQueryPacket(dnsClients, msg, host, dnsQType, buffer, length, dnsSearch)
length = processUnpackedDNSQueryPacket(dnsClients, msg, host, dnsQType, buffer, length, dnsSearch)
}
return length
return length, nil
}
func processDnsResponsePacket(svrConn net.Conn, dnsClients *dnsClientCache, cliAddr net.Addr, buffer []byte, length int, dnsSearch []string) bool {
func processDNSResponsePacket(
svrConn net.Conn,
dnsClients *dnsClientCache,
cliAddr net.Addr,
buffer []byte,
length int,
dnsSearch []string) (bool, int, error) {
var drop bool
msg := &dnsMsg{}
if !msg.unpackDnsMsg(buffer[:length]) {
glog.Warning("Unable to unpack DNS packet.")
return drop
msg := &dns.Msg{}
if err := msg.Unpack(buffer[:length]); err != nil {
glog.Warning("Unable to unpack DNS packet. Error is: %v", err)
return drop, length, err
}
// Query - Response bit that specifies whether this message is a query (0) or a response (1).
qr := msg.header.bits & 0x8000
if qr == 0 {
glog.Warning("DNS packet should be a response message.")
return drop
if msg.MsgHdr.Response == false {
return drop, length, fmt.Errorf("DNS packet should be a response message")
}
// QDCOUNT
if msg.header.qdCount != 1 {
glog.V(1).Infof("Number of entries in the reponse section of the DNS packet is: %d", msg.header.qdCount)
return drop
if len(msg.Question) != 1 {
glog.V(1).Infof("Number of entries in the reponse section of the DNS packet is: %d", len(msg.Answer))
return drop, length, nil
}
dnsQType := msg.question[0].qType
dnsQClass := msg.question[0].qClass
if packetRequiresDnsSuffix(dnsQType, dnsQClass) {
dnsQType := msg.Question[0].Qtype
dnsQClass := msg.Question[0].Qclass
if packetRequiresDNSSuffix(dnsQType, dnsQClass) {
host, _, err := net.SplitHostPort(cliAddr.String())
if err != nil {
glog.V(1).Infof("Failed to get host from client address: %v", err)
host = cliAddr.String()
}
rcode := msg.header.bits & 0xf
drop = processUnpackedDnsResponsePacket(svrConn, dnsClients, rcode, host, dnsQType, buffer, length, dnsSearch)
drop, length = processUnpackedDNSResponsePacket(svrConn, dnsClients, msg, msg.MsgHdr.Rcode, host, dnsQType, buffer, length, dnsSearch)
}
return drop
return drop, length, nil
}
func (udp *udpProxySocket) ProxyLoop(service ServicePortPortalName, myInfo *serviceInfo, proxier *Proxier) {
var buffer [4096]byte // 4KiB should be enough for most whole-packets
var dnsSearch []string
if isDnsService(service.Port) {
if isDNSService(service.Port) {
dnsSearch = []string{"", namespaceServiceDomain, serviceDomain, clusterDomain}
execer := exec.New()
ipconfigInterface := ipconfig.New(execer)
@@ -651,8 +532,11 @@ func (udp *udpProxySocket) ProxyLoop(service ServicePortPortalName, myInfo *serv
}
// If this is DNS query packet
if isDnsService(service.Port) {
n = processDnsQueryPacket(myInfo.dnsClients, cliAddr, buffer[:], n, dnsSearch)
if isDNSService(service.Port) {
n, err = processDNSQueryPacket(myInfo.dnsClients, cliAddr, buffer[:], n, dnsSearch)
if err != nil {
glog.Errorf("Process DNS query packet failed: %v", err)
}
}
// If this is a client we know already, reuse the connection and goroutine.
@@ -720,8 +604,11 @@ func (udp *udpProxySocket) proxyClient(cliAddr net.Addr, svrConn net.Conn, activ
}
drop := false
if isDnsService(service.Port) {
drop = processDnsResponsePacket(svrConn, dnsClients, cliAddr, buffer[:], n, dnsSearch)
if isDNSService(service.Port) {
drop, n, err = processDNSResponsePacket(svrConn, dnsClients, cliAddr, buffer[:], n, dnsSearch)
if err != nil {
glog.Errorf("Process DNS response packet failed: %v", err)
}
}
if !drop {

129
pkg/proxy/winuserspace/proxysocket_test.go
View File

@@ -1,129 +0,0 @@
/*
Copyright 2017 The Kubernetes Authors.
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 winuserspace
import (
"reflect"
"testing"
)
func TestPackUnpackDnsMsgUnqualifiedName(t *testing.T) {
msg := &dnsMsg{}
var buffer [4096]byte
msg.header.id = 1
msg.header.qdCount = 1
msg.question = make([]dnsQuestion, msg.header.qdCount)
msg.question[0].qClass = 0x01
msg.question[0].qType = 0x01
msg.question[0].qName.name = "kubernetes"
length, ok := msg.packDnsMsg(buffer[:])
if !ok {
t.Errorf("Pack DNS message failed.")
}
unpackedMsg := &dnsMsg{}
if !unpackedMsg.unpackDnsMsg(buffer[:length]) {
t.Errorf("Unpack DNS message failed.")
}
if !reflect.DeepEqual(msg, unpackedMsg) {
t.Errorf("Pack and Unpack DNS message are not consistent.")
}
}
func TestPackUnpackDnsMsgFqdn(t *testing.T) {
msg := &dnsMsg{}
var buffer [4096]byte
msg.header.id = 1
msg.header.qdCount = 1
msg.question = make([]dnsQuestion, msg.header.qdCount)
msg.question[0].qClass = 0x01
msg.question[0].qType = 0x01
msg.question[0].qName.name = "kubernetes.default.svc.cluster.local"
length, ok := msg.packDnsMsg(buffer[:])
if !ok {
t.Errorf("Pack DNS message failed.")
}
unpackedMsg := &dnsMsg{}
if !unpackedMsg.unpackDnsMsg(buffer[:length]) {
t.Errorf("Unpack DNS message failed.")
}
if !reflect.DeepEqual(msg, unpackedMsg) {
t.Errorf("Pack and Unpack DNS message are not consistent.")
}
}
func TestPackUnpackDnsMsgEmptyName(t *testing.T) {
msg := &dnsMsg{}
var buffer [4096]byte
msg.header.id = 1
msg.header.qdCount = 1
msg.question = make([]dnsQuestion, msg.header.qdCount)
msg.question[0].qClass = 0x01
msg.question[0].qType = 0x01
msg.question[0].qName.name = ""
length, ok := msg.packDnsMsg(buffer[:])
if !ok {
t.Errorf("Pack DNS message failed.")
}
unpackedMsg := &dnsMsg{}
if !unpackedMsg.unpackDnsMsg(buffer[:length]) {
t.Errorf("Unpack DNS message failed.")
}
if !reflect.DeepEqual(msg, unpackedMsg) {
t.Errorf("Pack and Unpack DNS message are not consistent.")
}
}
func TestPackUnpackDnsMsgMultipleQuestions(t *testing.T) {
msg := &dnsMsg{}
var buffer [4096]byte
msg.header.id = 1
msg.header.qdCount = 2
msg.question = make([]dnsQuestion, msg.header.qdCount)
msg.question[0].qClass = 0x01
msg.question[0].qType = 0x01
msg.question[0].qName.name = "kubernetes"
msg.question[1].qClass = 0x01
msg.question[1].qType = 0x1c
msg.question[1].qName.name = "kubernetes.default"
length, ok := msg.packDnsMsg(buffer[:])
if !ok {
t.Errorf("Pack DNS message failed.")
}
unpackedMsg := &dnsMsg{}
if !unpackedMsg.unpackDnsMsg(buffer[:length]) {
t.Errorf("Unpack DNS message failed.")
}
if !reflect.DeepEqual(msg, unpackedMsg) {
t.Errorf("Pack and Unpack DNS message are not consistent.")
}
}