1+ // +build windows
2+
13/*
24Copyright 2019 The Kubernetes Authors.
35
@@ -17,40 +19,131 @@ limitations under the License.
1719package dns
1820
1921import (
20- "bytes"
21- "os/exec"
22+ "fmt"
2223 "strings"
24+ "syscall"
25+ "unsafe"
26+
27+ "golang.org/x/sys/windows"
28+ "golang.org/x/sys/windows/registry"
2329)
2430
25- const etcHostsFile = "C:/Windows/System32/drivers/etc/hosts"
31+ const (
32+ etcHostsFile = "C:/Windows/System32/drivers/etc/hosts"
33+ netRegistry = `System\CurrentControlSet\Services\TCPIP\Parameters`
34+ netIfacesRegistry = `System\CurrentControlSet\Services\TCPIP\Parameters\Interfaces`
35+ maxHostnameLen = 128
36+ maxDomainNameLen = 128
37+ maxScopeIDLen = 256
38+ )
2639
27- func getDNSSuffixList () []string {
28- output := runCommand ("powershell" , "-Command" , "(Get-DnsClient)[0].SuffixSearchList" )
29- if len (output ) > 0 {
30- return strings .Split (output , "\r \n " )
31- }
40+ // FixedInfo information: https://docs.microsoft.com/en-us/windows/win32/api/iptypes/ns-iptypes-fixed_info_w2ksp1
41+ type FixedInfo struct {
42+ HostName [maxHostnameLen + 4 ]byte
43+ DomainName [maxDomainNameLen + 4 ]byte
44+ CurrentDNSServer * syscall.IpAddrString
45+ DNSServerList syscall.IpAddrString
46+ NodeType uint32
47+ ScopeID [maxScopeIDLen + 4 ]byte
48+ EnableRouting uint32
49+ EnableProxy uint32
50+ EnableDNS uint32
51+ }
52+
53+ var (
54+ // GetNetworkParams can be found in iphlpapi.dll
55+ // see: https://docs.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getnetworkparams?redirectedfrom=MSDN
56+ iphlpapidll = windows .MustLoadDLL ("iphlpapi.dll" )
57+ procGetNetworkParams = iphlpapidll .MustFindProc ("GetNetworkParams" )
58+ )
3259
33- panic ("Could not find DNS search list!" )
60+ func elemInList (elem string , list []string ) bool {
61+ for _ , e := range list {
62+ if e == elem {
63+ return true
64+ }
65+ }
66+ return false
3467}
3568
36- func getDNSServerList () [] string {
37- output := runCommand ( "powershell" , "-Command" , "(Get-DnsClientServerAddress).ServerAddresses" )
38- if len ( output ) > 0 {
39- return strings . Split ( output , " \r \n " )
69+ func getRegistryValue ( reg , key string ) string {
70+ regKey , err := registry . OpenKey ( registry . LOCAL_MACHINE , reg , registry . QUERY_VALUE )
71+ if err != nil {
72+ return ""
4073 }
74+ defer regKey .Close ()
4175
42- panic ("Could not find DNS Server list!" )
76+ regValue , _ , err := regKey .GetStringValue (key )
77+ if err != nil {
78+ return ""
79+ }
80+ return regValue
4381}
4482
45- func runCommand (name string , arg ... string ) string {
46- var out bytes.Buffer
47- cmd := exec .Command (name , arg ... )
48- cmd .Stdout = & out
83+ // getDNSSuffixList reads DNS config file and returns the list of configured DNS suffixes
84+ func getDNSSuffixList () []string {
85+ // We start with the general suffix list that apply to all network connections.
86+ allSuffixes := []string {}
87+ suffixes := getRegistryValue (netRegistry , "SearchList" )
88+ if suffixes != "" {
89+ allSuffixes = strings .Split (suffixes , "," )
90+ }
4991
50- err := cmd .Run ()
92+ // Then we append the network-specific DNS suffix lists.
93+ regKey , err := registry .OpenKey (registry .LOCAL_MACHINE , netIfacesRegistry , registry .ENUMERATE_SUB_KEYS )
5194 if err != nil {
5295 panic (err )
5396 }
97+ defer regKey .Close ()
5498
55- return strings .TrimSpace (out .String ())
99+ ifaces , err := regKey .ReadSubKeyNames (0 )
100+ if err != nil {
101+ panic (err )
102+ }
103+ for _ , iface := range ifaces {
104+ suffixes := getRegistryValue (fmt .Sprintf ("%s\\ %s" , netIfacesRegistry , iface ), "SearchList" )
105+ if suffixes == "" {
106+ continue
107+ }
108+ for _ , suffix := range strings .Split (suffixes , "," ) {
109+ if ! elemInList (suffix , allSuffixes ) {
110+ allSuffixes = append (allSuffixes , suffix )
111+ }
112+ }
113+ }
114+
115+ return allSuffixes
116+ }
117+
118+ func getNetworkParams () * FixedInfo {
119+ // We don't know how big we should make the byte buffer, but the call will tell us by
120+ // setting the size afterwards.
121+ var size int
122+ buffer := make ([]byte , 1 )
123+ procGetNetworkParams .Call (
124+ uintptr (unsafe .Pointer (& buffer [0 ])),
125+ uintptr (unsafe .Pointer (& size )),
126+ )
127+
128+ buffer = make ([]byte , size )
129+ procGetNetworkParams .Call (
130+ uintptr (unsafe .Pointer (& buffer [0 ])),
131+ uintptr (unsafe .Pointer (& size )),
132+ )
133+
134+ info := (* FixedInfo )(unsafe .Pointer (& buffer [0 ]))
135+ return info
136+ }
137+
138+ func getDNSServerList () []string {
139+ dnsServerList := []string {}
140+ fixedInfo := getNetworkParams ()
141+ list := & (fixedInfo .DNSServerList )
142+
143+ for list != nil {
144+ dnsServer := strings .TrimRight (string (list .IpAddress .String [:]), "\x00 " )
145+ dnsServerList = append (dnsServerList , dnsServer )
146+ list = list .Next
147+ }
148+ return dnsServerList
56149}
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