mirror of
https://github.com/golang/go
synced 2024-11-12 07:10:22 -07:00
net: use contexts for cgo-based DNS resolution
Although calls to getaddrinfo can't be portably interrupted, we still benefit from more granular resource management by pushing the context downwards. Fixes #15321 Change-Id: I5506195fc6493080410e3d46aaa3fe02018a24fe Reviewed-on: https://go-review.googlesource.com/22961 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
parent
9edb27e76f
commit
636670b8db
@ -6,6 +6,8 @@
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package net
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import "context"
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func init() { netGo = true }
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type addrinfoErrno int
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@ -14,22 +16,22 @@ func (eai addrinfoErrno) Error() string { return "<nil>" }
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func (eai addrinfoErrno) Temporary() bool { return false }
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func (eai addrinfoErrno) Timeout() bool { return false }
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func cgoLookupHost(name string) (addrs []string, err error, completed bool) {
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func cgoLookupHost(ctx context.Context, name string) (addrs []string, err error, completed bool) {
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return nil, nil, false
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}
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func cgoLookupPort(network, service string) (port int, err error, completed bool) {
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func cgoLookupPort(ctx context.Context, network, service string) (port int, err error, completed bool) {
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return 0, nil, false
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}
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func cgoLookupIP(name string) (addrs []IPAddr, err error, completed bool) {
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func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
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return nil, nil, false
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}
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func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
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func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
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return "", nil, false
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}
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func cgoLookupPTR(addr string) (ptrs []string, err error, completed bool) {
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func cgoLookupPTR(ctx context.Context, addr string) (ptrs []string, err error, completed bool) {
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return nil, nil, false
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}
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@ -19,6 +19,7 @@ package net
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import "C"
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import (
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"context"
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"syscall"
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"unsafe"
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)
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@ -32,18 +33,31 @@ func (eai addrinfoErrno) Error() string { return C.GoString(C.gai_strerror(C.i
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func (eai addrinfoErrno) Temporary() bool { return eai == C.EAI_AGAIN }
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func (eai addrinfoErrno) Timeout() bool { return false }
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func cgoLookupHost(name string) (hosts []string, err error, completed bool) {
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addrs, err, completed := cgoLookupIP(name)
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type portLookupResult struct {
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port int
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err error
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}
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type ipLookupResult struct {
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addrs []IPAddr
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cname string
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err error
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}
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type reverseLookupResult struct {
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names []string
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err error
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}
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func cgoLookupHost(ctx context.Context, name string) (hosts []string, err error, completed bool) {
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addrs, err, completed := cgoLookupIP(ctx, name)
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for _, addr := range addrs {
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hosts = append(hosts, addr.String())
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}
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return
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}
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func cgoLookupPort(network, service string) (port int, err error, completed bool) {
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acquireThread()
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defer releaseThread()
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func cgoLookupPort(ctx context.Context, network, service string) (port int, err error, completed bool) {
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var hints C.struct_addrinfo
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switch network {
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case "": // no hints
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@ -64,11 +78,27 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
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hints.ai_family = C.AF_INET6
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}
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}
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if ctx.Done() == nil {
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port, err := cgoLookupServicePort(&hints, network, service)
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return port, err, true
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}
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result := make(chan portLookupResult, 1)
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go cgoPortLookup(result, &hints, network, service)
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select {
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case r := <-result:
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return r.port, r.err, true
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case <-ctx.Done():
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// Since there isn't a portable way to cancel the lookup,
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// we just let it finish and write to the buffered channel.
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return 0, mapErr(ctx.Err()), false
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}
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}
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func cgoLookupServicePort(hints *C.struct_addrinfo, network, service string) (port int, err error) {
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s := C.CString(service)
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var res *C.struct_addrinfo
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defer C.free(unsafe.Pointer(s))
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gerrno, err := C.getaddrinfo(nil, s, &hints, &res)
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gerrno, err := C.getaddrinfo(nil, s, hints, &res)
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if gerrno != 0 {
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switch gerrno {
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case C.EAI_SYSTEM:
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@ -78,7 +108,7 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
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default:
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err = addrinfoErrno(gerrno)
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}
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return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}, true
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return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
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}
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defer C.freeaddrinfo(res)
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@ -87,17 +117,22 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
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case C.AF_INET:
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sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.ai_addr))
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p := (*[2]byte)(unsafe.Pointer(&sa.Port))
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return int(p[0])<<8 | int(p[1]), nil, true
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return int(p[0])<<8 | int(p[1]), nil
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case C.AF_INET6:
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sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.ai_addr))
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p := (*[2]byte)(unsafe.Pointer(&sa.Port))
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return int(p[0])<<8 | int(p[1]), nil, true
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return int(p[0])<<8 | int(p[1]), nil
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}
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}
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return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}, true
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return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}
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}
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func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, completed bool) {
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func cgoPortLookup(result chan<- portLookupResult, hints *C.struct_addrinfo, network, service string) {
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port, err := cgoLookupServicePort(hints, network, service)
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result <- portLookupResult{port, err}
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}
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func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error) {
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acquireThread()
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defer releaseThread()
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@ -127,7 +162,7 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
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default:
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err = addrinfoErrno(gerrno)
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}
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return nil, "", &DNSError{Err: err.Error(), Name: name}, true
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return nil, "", &DNSError{Err: err.Error(), Name: name}
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}
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defer C.freeaddrinfo(res)
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@ -156,17 +191,42 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
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addrs = append(addrs, addr)
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}
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}
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return addrs, cname, nil, true
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return addrs, cname, nil
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}
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func cgoLookupIP(name string) (addrs []IPAddr, err error, completed bool) {
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addrs, _, err, completed = cgoLookupIPCNAME(name)
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return
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func cgoIPLookup(result chan<- ipLookupResult, name string) {
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addrs, cname, err := cgoLookupIPCNAME(name)
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result <- ipLookupResult{addrs, cname, err}
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}
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func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
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_, cname, err, completed = cgoLookupIPCNAME(name)
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return
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func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
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if ctx.Done() == nil {
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addrs, _, err = cgoLookupIPCNAME(name)
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return addrs, err, true
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}
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result := make(chan ipLookupResult, 1)
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go cgoIPLookup(result, name)
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select {
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case r := <-result:
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return r.addrs, r.err, true
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case <-ctx.Done():
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return nil, mapErr(ctx.Err()), false
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}
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}
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func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
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if ctx.Done() == nil {
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_, cname, err = cgoLookupIPCNAME(name)
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return cname, err, true
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}
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result := make(chan ipLookupResult, 1)
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go cgoIPLookup(result, name)
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select {
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case r := <-result:
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return r.cname, r.err, true
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case <-ctx.Done():
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return "", mapErr(ctx.Err()), false
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}
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}
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// These are roughly enough for the following:
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@ -182,10 +242,7 @@ const (
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maxNameinfoLen = 4096
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)
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func cgoLookupPTR(addr string) ([]string, error, bool) {
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acquireThread()
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defer releaseThread()
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func cgoLookupPTR(ctx context.Context, addr string) (names []string, err error, completed bool) {
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var zone string
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ip := parseIPv4(addr)
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if ip == nil {
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@ -198,9 +255,26 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
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if sa == nil {
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return nil, &DNSError{Err: "invalid address " + ip.String(), Name: addr}, true
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}
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var err error
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var b []byte
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if ctx.Done() == nil {
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names, err := cgoLookupAddrPTR(addr, sa, salen)
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return names, err, true
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}
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result := make(chan reverseLookupResult, 1)
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go cgoReverseLookup(result, addr, sa, salen)
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select {
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case r := <-result:
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return r.names, r.err, true
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case <-ctx.Done():
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return nil, mapErr(ctx.Err()), false
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}
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}
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func cgoLookupAddrPTR(addr string, sa *C.struct_sockaddr, salen C.socklen_t) (names []string, err error) {
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acquireThread()
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defer releaseThread()
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var gerrno int
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var b []byte
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for l := nameinfoLen; l <= maxNameinfoLen; l *= 2 {
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b = make([]byte, l)
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gerrno, err = cgoNameinfoPTR(b, sa, salen)
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@ -217,16 +291,20 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
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default:
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err = addrinfoErrno(gerrno)
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}
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return nil, &DNSError{Err: err.Error(), Name: addr}, true
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return nil, &DNSError{Err: err.Error(), Name: addr}
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}
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for i := 0; i < len(b); i++ {
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if b[i] == 0 {
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b = b[:i]
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break
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}
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}
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return []string{absDomainName(b)}, nil, true
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return []string{absDomainName(b)}, nil
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}
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func cgoReverseLookup(result chan<- reverseLookupResult, addr string, sa *C.struct_sockaddr, salen C.socklen_t) {
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names, err := cgoLookupAddrPTR(addr, sa, salen)
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result <- reverseLookupResult{names, err}
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}
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func cgoSockaddr(ip IP, zone string) (*C.struct_sockaddr, C.socklen_t) {
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@ -13,15 +13,70 @@ import (
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)
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func TestCgoLookupIP(t *testing.T) {
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host := "localhost"
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_, err, ok := cgoLookupIP(host)
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ctx := context.Background()
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_, err, ok := cgoLookupIP(ctx, "localhost")
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if !ok {
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t.Errorf("cgoLookupIP must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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if _, err := goLookupIP(context.Background(), host); err != nil {
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}
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func TestCgoLookupIPWithCancel(t *testing.T) {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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_, err, ok := cgoLookupIP(ctx, "localhost")
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if !ok {
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t.Errorf("cgoLookupIP must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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}
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func TestCgoLookupPort(t *testing.T) {
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ctx := context.Background()
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_, err, ok := cgoLookupPort(ctx, "tcp", "smtp")
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if !ok {
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t.Errorf("cgoLookupPort must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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}
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func TestCgoLookupPortWithCancel(t *testing.T) {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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_, err, ok := cgoLookupPort(ctx, "tcp", "smtp")
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if !ok {
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t.Errorf("cgoLookupPort must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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}
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func TestCgoLookupPTR(t *testing.T) {
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ctx := context.Background()
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_, err, ok := cgoLookupPTR(ctx, "127.0.0.1")
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if !ok {
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t.Errorf("cgoLookupPTR must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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}
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func TestCgoLookupPTRWithCancel(t *testing.T) {
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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_, err, ok := cgoLookupPTR(ctx, "127.0.0.1")
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if !ok {
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t.Errorf("cgoLookupPTR must not be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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}
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@ -55,7 +55,7 @@ func lookupProtocol(_ context.Context, name string) (int, error) {
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func lookupHost(ctx context.Context, host string) (addrs []string, err error) {
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order := systemConf().hostLookupOrder(host)
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if order == hostLookupCgo {
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if addrs, err, ok := cgoLookupHost(host); ok {
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if addrs, err, ok := cgoLookupHost(ctx, host); ok {
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return addrs, err
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}
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// cgo not available (or netgo); fall back to Go's DNS resolver
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@ -67,8 +67,7 @@ func lookupHost(ctx context.Context, host string) (addrs []string, err error) {
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func lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
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order := systemConf().hostLookupOrder(host)
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if order == hostLookupCgo {
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// TODO(bradfitz): push down ctx, or at least its deadline to start
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if addrs, err, ok := cgoLookupIP(host); ok {
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if addrs, err, ok := cgoLookupIP(ctx, host); ok {
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return addrs, err
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}
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// cgo not available (or netgo); fall back to Go's DNS resolver
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@ -84,7 +83,7 @@ func lookupPort(ctx context.Context, network, service string) (int, error) {
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// files might be on a remote filesystem, though. This should
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// probably race goroutines if ctx != context.Background().
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if systemConf().canUseCgo() {
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if port, err, ok := cgoLookupPort(network, service); ok {
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if port, err, ok := cgoLookupPort(ctx, network, service); ok {
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return port, err
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}
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}
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@ -93,8 +92,7 @@ func lookupPort(ctx context.Context, network, service string) (int, error) {
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func lookupCNAME(ctx context.Context, name string) (string, error) {
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if systemConf().canUseCgo() {
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// TODO: use ctx. issue 15321. Or race goroutines.
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if cname, err, ok := cgoLookupCNAME(name); ok {
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if cname, err, ok := cgoLookupCNAME(ctx, name); ok {
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return cname, err
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}
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}
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@ -161,7 +159,7 @@ func lookupTXT(ctx context.Context, name string) ([]string, error) {
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func lookupAddr(ctx context.Context, addr string) ([]string, error) {
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if systemConf().canUseCgo() {
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if ptrs, err, ok := cgoLookupPTR(addr); ok {
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if ptrs, err, ok := cgoLookupPTR(ctx, addr); ok {
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return ptrs, err
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}
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}
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@ -14,14 +14,15 @@ import (
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func TestGoLookupIP(t *testing.T) {
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host := "localhost"
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_, err, ok := cgoLookupIP(host)
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ctx := context.Background()
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_, err, ok := cgoLookupIP(ctx, host)
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if ok {
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t.Errorf("cgoLookupIP must be a placeholder")
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}
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if err != nil {
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t.Error(err)
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}
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if _, err := goLookupIP(context.Background(), host); err != nil {
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if _, err := goLookupIP(ctx, host); err != nil {
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t.Error(err)
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}
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}
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