1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
9 "internal/syscall/windows"
17 // cgoAvailable set to true to indicate that the cgo resolver
18 // is available on Windows. Note that on Windows the cgo resolver
19 // does not actually use cgo.
20 const cgoAvailable = true
23 _DNS_ERROR_RCODE_NAME_ERROR = syscall.Errno(9003)
24 _DNS_INFO_NO_RECORDS = syscall.Errno(9501)
26 _WSAHOST_NOT_FOUND = syscall.Errno(11001)
27 _WSATRY_AGAIN = syscall.Errno(11002)
28 _WSATYPE_NOT_FOUND = syscall.Errno(10109)
31 func winError(call string, err error) error {
33 case _WSAHOST_NOT_FOUND, _DNS_ERROR_RCODE_NAME_ERROR, _DNS_INFO_NO_RECORDS:
36 return os.NewSyscallError(call, err)
39 func getprotobyname(name string) (proto int, err error) {
40 p, err := syscall.GetProtoByName(name)
42 return 0, winError("getprotobyname", err)
44 return int(p.Proto), nil
47 // lookupProtocol looks up IP protocol name and returns correspondent protocol number.
48 func lookupProtocol(ctx context.Context, name string) (int, error) {
49 // GetProtoByName return value is stored in thread local storage.
50 // Start new os thread before the call to prevent races.
55 ch := make(chan result) // unbuffered
59 runtime.LockOSThread()
60 defer runtime.UnlockOSThread()
61 proto, err := getprotobyname(name)
63 case ch <- result{proto: proto, err: err}:
70 if proto, err := lookupProtocolMap(name); err == nil {
74 dnsError := &DNSError{Err: r.err.Error(), Name: name}
75 if r.err == errNoSuchHost {
76 dnsError.IsNotFound = true
82 return 0, mapErr(ctx.Err())
86 func (r *Resolver) lookupHost(ctx context.Context, name string) ([]string, error) {
87 ips, err := r.lookupIP(ctx, "ip", name)
91 addrs := make([]string, 0, len(ips))
92 for _, ip := range ips {
93 addrs = append(addrs, ip.String())
98 func (r *Resolver) lookupIP(ctx context.Context, network, name string) ([]IPAddr, error) {
99 if order, conf := systemConf().hostLookupOrder(r, name); order != hostLookupCgo {
100 return r.goLookupIP(ctx, network, name, order, conf)
103 // TODO(bradfitz,brainman): use ctx more. See TODO below.
105 var family int32 = syscall.AF_UNSPEC
106 switch ipVersion(network) {
108 family = syscall.AF_INET
110 family = syscall.AF_INET6
113 getaddr := func() ([]IPAddr, error) {
115 defer releaseThread()
116 hints := syscall.AddrinfoW{
118 Socktype: syscall.SOCK_STREAM,
119 Protocol: syscall.IPPROTO_IP,
121 var result *syscall.AddrinfoW
122 name16p, err := syscall.UTF16PtrFromString(name)
124 return nil, &DNSError{Name: name, Err: err.Error()}
127 dnsConf := getSystemDNSConfig()
131 for i := 0; i < dnsConf.attempts; i++ {
132 e = syscall.GetAddrInfoW(name16p, nil, &hints, &result)
133 if e == nil || e != _WSATRY_AGAIN || time.Since(start) > dnsConf.timeout {
138 err := winError("getaddrinfow", e)
139 dnsError := &DNSError{Err: err.Error(), Name: name}
140 if err == errNoSuchHost {
141 dnsError.IsNotFound = true
145 defer syscall.FreeAddrInfoW(result)
146 addrs := make([]IPAddr, 0, 5)
147 for ; result != nil; result = result.Next {
148 addr := unsafe.Pointer(result.Addr)
149 switch result.Family {
150 case syscall.AF_INET:
151 a := (*syscall.RawSockaddrInet4)(addr).Addr
152 addrs = append(addrs, IPAddr{IP: copyIP(a[:])})
153 case syscall.AF_INET6:
154 a := (*syscall.RawSockaddrInet6)(addr).Addr
155 zone := zoneCache.name(int((*syscall.RawSockaddrInet6)(addr).Scope_id))
156 addrs = append(addrs, IPAddr{IP: copyIP(a[:]), Zone: zone})
158 return nil, &DNSError{Err: syscall.EWINDOWS.Error(), Name: name}
170 if ctx.Err() == nil {
171 ch = make(chan ret, 1)
173 addr, err := getaddr()
174 ch <- ret{addrs: addr, err: err}
180 return r.addrs, r.err
182 // TODO(bradfitz,brainman): cancel the ongoing
183 // GetAddrInfoW? It would require conditionally using
184 // GetAddrInfoEx with lpOverlapped, which requires
185 // Windows 8 or newer. I guess we'll need oldLookupIP,
186 // newLookupIP, and newerLookUP.
188 // For now we just let it finish and write to the
190 return nil, &DNSError{
192 Err: ctx.Err().Error(),
193 IsTimeout: ctx.Err() == context.DeadlineExceeded,
198 func (r *Resolver) lookupPort(ctx context.Context, network, service string) (int, error) {
199 if systemConf().mustUseGoResolver(r) {
200 return lookupPortMap(network, service)
203 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
205 defer releaseThread()
207 var hints syscall.AddrinfoW
210 case "ip": // no hints
211 case "tcp", "tcp4", "tcp6":
212 hints.Socktype = syscall.SOCK_STREAM
213 hints.Protocol = syscall.IPPROTO_TCP
214 case "udp", "udp4", "udp6":
215 hints.Socktype = syscall.SOCK_DGRAM
216 hints.Protocol = syscall.IPPROTO_UDP
218 return 0, &DNSError{Err: "unknown network", Name: network + "/" + service}
221 switch ipVersion(network) {
223 hints.Family = syscall.AF_INET
225 hints.Family = syscall.AF_INET6
228 var result *syscall.AddrinfoW
229 e := syscall.GetAddrInfoW(nil, syscall.StringToUTF16Ptr(service), &hints, &result)
231 if port, err := lookupPortMap(network, service); err == nil {
235 // The _WSATYPE_NOT_FOUND error is returned by GetAddrInfoW
236 // when the service name is unknown. We are also checking
237 // for _WSAHOST_NOT_FOUND here to match the cgo (unix) version
238 // cgo_unix.go (cgoLookupServicePort).
239 if e == _WSATYPE_NOT_FOUND || e == _WSAHOST_NOT_FOUND {
240 return 0, &DNSError{Err: "unknown port", Name: network + "/" + service, IsNotFound: true}
242 err := os.NewSyscallError("getaddrinfow", e)
243 return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
245 defer syscall.FreeAddrInfoW(result)
247 return 0, &DNSError{Err: syscall.EINVAL.Error(), Name: network + "/" + service}
249 addr := unsafe.Pointer(result.Addr)
250 switch result.Family {
251 case syscall.AF_INET:
252 a := (*syscall.RawSockaddrInet4)(addr)
253 return int(syscall.Ntohs(a.Port)), nil
254 case syscall.AF_INET6:
255 a := (*syscall.RawSockaddrInet6)(addr)
256 return int(syscall.Ntohs(a.Port)), nil
258 return 0, &DNSError{Err: syscall.EINVAL.Error(), Name: network + "/" + service}
261 func (r *Resolver) lookupCNAME(ctx context.Context, name string) (string, error) {
262 if order, conf := systemConf().hostLookupOrder(r, name); order != hostLookupCgo {
263 return r.goLookupCNAME(ctx, name, order, conf)
266 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
268 defer releaseThread()
269 var rec *syscall.DNSRecord
270 e := syscall.DnsQuery(name, syscall.DNS_TYPE_CNAME, 0, nil, &rec, nil)
271 // windows returns DNS_INFO_NO_RECORDS if there are no CNAME-s
272 if errno, ok := e.(syscall.Errno); ok && errno == syscall.DNS_INFO_NO_RECORDS {
273 // if there are no aliases, the canonical name is the input name
274 return absDomainName(name), nil
277 err := winError("dnsquery", e)
278 return "", &DNSError{Err: err.Error(), Name: name, IsNotFound: err == errNoSuchHost}
280 defer syscall.DnsRecordListFree(rec, 1)
282 resolved := resolveCNAME(syscall.StringToUTF16Ptr(name), rec)
283 cname := windows.UTF16PtrToString(resolved)
284 return absDomainName(cname), nil
287 func (r *Resolver) lookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
288 if systemConf().mustUseGoResolver(r) {
289 return r.goLookupSRV(ctx, service, proto, name)
291 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
293 defer releaseThread()
295 if service == "" && proto == "" {
298 target = "_" + service + "._" + proto + "." + name
300 var rec *syscall.DNSRecord
301 e := syscall.DnsQuery(target, syscall.DNS_TYPE_SRV, 0, nil, &rec, nil)
303 err := winError("dnsquery", e)
304 return "", nil, &DNSError{Err: err.Error(), Name: name, IsNotFound: err == errNoSuchHost}
306 defer syscall.DnsRecordListFree(rec, 1)
308 srvs := make([]*SRV, 0, 10)
309 for _, p := range validRecs(rec, syscall.DNS_TYPE_SRV, target) {
310 v := (*syscall.DNSSRVData)(unsafe.Pointer(&p.Data[0]))
311 srvs = append(srvs, &SRV{absDomainName(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Target))[:])), v.Port, v.Priority, v.Weight})
313 byPriorityWeight(srvs).sort()
314 return absDomainName(target), srvs, nil
317 func (r *Resolver) lookupMX(ctx context.Context, name string) ([]*MX, error) {
318 if systemConf().mustUseGoResolver(r) {
319 return r.goLookupMX(ctx, name)
321 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
323 defer releaseThread()
324 var rec *syscall.DNSRecord
325 e := syscall.DnsQuery(name, syscall.DNS_TYPE_MX, 0, nil, &rec, nil)
327 err := winError("dnsquery", e)
328 return nil, &DNSError{Err: err.Error(), Name: name, IsNotFound: err == errNoSuchHost}
330 defer syscall.DnsRecordListFree(rec, 1)
332 mxs := make([]*MX, 0, 10)
333 for _, p := range validRecs(rec, syscall.DNS_TYPE_MX, name) {
334 v := (*syscall.DNSMXData)(unsafe.Pointer(&p.Data[0]))
335 mxs = append(mxs, &MX{absDomainName(windows.UTF16PtrToString(v.NameExchange)), v.Preference})
341 func (r *Resolver) lookupNS(ctx context.Context, name string) ([]*NS, error) {
342 if systemConf().mustUseGoResolver(r) {
343 return r.goLookupNS(ctx, name)
345 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
347 defer releaseThread()
348 var rec *syscall.DNSRecord
349 e := syscall.DnsQuery(name, syscall.DNS_TYPE_NS, 0, nil, &rec, nil)
351 err := winError("dnsquery", e)
352 return nil, &DNSError{Err: err.Error(), Name: name, IsNotFound: err == errNoSuchHost}
354 defer syscall.DnsRecordListFree(rec, 1)
356 nss := make([]*NS, 0, 10)
357 for _, p := range validRecs(rec, syscall.DNS_TYPE_NS, name) {
358 v := (*syscall.DNSPTRData)(unsafe.Pointer(&p.Data[0]))
359 nss = append(nss, &NS{absDomainName(syscall.UTF16ToString((*[256]uint16)(unsafe.Pointer(v.Host))[:]))})
364 func (r *Resolver) lookupTXT(ctx context.Context, name string) ([]string, error) {
365 if systemConf().mustUseGoResolver(r) {
366 return r.goLookupTXT(ctx, name)
368 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
370 defer releaseThread()
371 var rec *syscall.DNSRecord
372 e := syscall.DnsQuery(name, syscall.DNS_TYPE_TEXT, 0, nil, &rec, nil)
374 err := winError("dnsquery", e)
375 return nil, &DNSError{Err: err.Error(), Name: name, IsNotFound: err == errNoSuchHost}
377 defer syscall.DnsRecordListFree(rec, 1)
379 txts := make([]string, 0, 10)
380 for _, p := range validRecs(rec, syscall.DNS_TYPE_TEXT, name) {
381 d := (*syscall.DNSTXTData)(unsafe.Pointer(&p.Data[0]))
383 for _, v := range (*[1 << 10]*uint16)(unsafe.Pointer(&(d.StringArray[0])))[:d.StringCount:d.StringCount] {
384 s += windows.UTF16PtrToString(v)
386 txts = append(txts, s)
391 func (r *Resolver) lookupAddr(ctx context.Context, addr string) ([]string, error) {
392 if order, conf := systemConf().addrLookupOrder(r, addr); order != hostLookupCgo {
393 return r.goLookupPTR(ctx, addr, order, conf)
396 // TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
398 defer releaseThread()
399 arpa, err := reverseaddr(addr)
403 var rec *syscall.DNSRecord
404 e := syscall.DnsQuery(arpa, syscall.DNS_TYPE_PTR, 0, nil, &rec, nil)
406 err := winError("dnsquery", e)
407 return nil, &DNSError{Err: err.Error(), Name: addr, IsNotFound: err == errNoSuchHost}
409 defer syscall.DnsRecordListFree(rec, 1)
411 ptrs := make([]string, 0, 10)
412 for _, p := range validRecs(rec, syscall.DNS_TYPE_PTR, arpa) {
413 v := (*syscall.DNSPTRData)(unsafe.Pointer(&p.Data[0]))
414 ptrs = append(ptrs, absDomainName(windows.UTF16PtrToString(v.Host)))
419 const dnsSectionMask = 0x0003
421 // returns only results applicable to name and resolves CNAME entries.
422 func validRecs(r *syscall.DNSRecord, dnstype uint16, name string) []*syscall.DNSRecord {
423 cname := syscall.StringToUTF16Ptr(name)
424 if dnstype != syscall.DNS_TYPE_CNAME {
425 cname = resolveCNAME(cname, r)
427 rec := make([]*syscall.DNSRecord, 0, 10)
428 for p := r; p != nil; p = p.Next {
429 // in case of a local machine, DNS records are returned with DNSREC_QUESTION flag instead of DNS_ANSWER
430 if p.Dw&dnsSectionMask != syscall.DnsSectionAnswer && p.Dw&dnsSectionMask != syscall.DnsSectionQuestion {
433 if p.Type != dnstype {
436 if !syscall.DnsNameCompare(cname, p.Name) {
444 // returns the last CNAME in chain.
445 func resolveCNAME(name *uint16, r *syscall.DNSRecord) *uint16 {
446 // limit cname resolving to 10 in case of an infinite CNAME loop
448 for cnameloop := 0; cnameloop < 10; cnameloop++ {
449 for p := r; p != nil; p = p.Next {
450 if p.Dw&dnsSectionMask != syscall.DnsSectionAnswer {
453 if p.Type != syscall.DNS_TYPE_CNAME {
456 if !syscall.DnsNameCompare(name, p.Name) {
459 name = (*syscall.DNSPTRData)(unsafe.Pointer(&r.Data[0])).Host
467 // concurrentThreadsLimit returns the number of threads we permit to
468 // run concurrently doing DNS lookups.
469 func concurrentThreadsLimit() int {