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Properly expose cancellation

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Signed-off-by: Aaron Klotz <aaron@tailscale.com>
This commit is contained in:
Aaron Klotz 2021-12-08 13:14:19 -07:00
parent 17abf201a3
commit ef99c55d1b
2 changed files with 16 additions and 10 deletions
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9
cmd/dnsapc/dnsapc.go
View File

@ -10,13 +10,14 @@
) )
func main() { func main() {
result, err := winutil.DnsQuery("www.tailscale.com", windows.DNS_TYPE_A, winutil.DNS_QUERY_STANDARD, nil, 0) result, err := winutil.DNSQuery("www.tailscale.com", windows.DNS_TYPE_A, winutil.DNS_QUERY_STANDARD, nil, 0)
if err != nil { if err != nil {
fmt.Fprintln(os.Stderr, err) fmt.Fprintln(os.Stderr, err)
return return
} }
finalStatus := result.QueryStatus qresult := result.Wait()
finalStatus := qresult.QueryStatus
fmt.Printf("Query status: %v", finalStatus) fmt.Printf("Query status: %v", finalStatus)
if finalStatus != 0 { if finalStatus != 0 {
fmt.Printf(" (%v)\n", windows.Errno(finalStatus)) fmt.Printf(" (%v)\n", windows.Errno(finalStatus))
@ -25,7 +26,7 @@ func main() {
} }
count := 0 count := 0
for rec := result.QueryRecords; rec != nil; rec = rec.Next { for rec := qresult.QueryRecords; rec != nil; rec = rec.Next {
name := windows.UTF16PtrToString(rec.Name) name := windows.UTF16PtrToString(rec.Name)
fmt.Printf("Record %d: %s, type %v", count, name, rec.Type) fmt.Printf("Record %d: %s, type %v", count, name, rec.Type)
switch rec.Type { switch rec.Type {
@ -42,5 +43,5 @@ func main() {
count++ count++
} }
result.Close() qresult.Close()
} }

17
util/winutil/dnsapc_windows.go
View File

@ -41,7 +41,7 @@ type DNSServerList struct {
apcCallback uintptr apcCallback uintptr
) )
func newDnsInvoker(qname string, qtype uint16, qoptions uint64, srvList *DNSServerList, ifaceIdx uint32) (*invoker, error) { func newDNSInvoker(qname string, qtype uint16, qoptions uint64, srvList *DNSServerList, ifaceIdx uint32) (*invoker, error) {
once.Do(func() { once.Do(func() {
cbInfo := APCCallbackInfo{reflect.TypeOf(dnsQueryExApc), resolver{}} cbInfo := APCCallbackInfo{reflect.TypeOf(dnsQueryExApc), resolver{}}
apcCallback = RegisterAPCCallback(cbInfo) apcCallback = RegisterAPCCallback(cbInfo)
@ -87,16 +87,22 @@ func (i *invoker) Begin() *APCChannel {
return &i.done return &i.done
} }
func (i *invoker) Wait() { func (i *invoker) Wait() *DNSQueryResult {
<-i.done <-i.done
return &i.result
} }
func (i *invoker) Cancel() error { func (i *invoker) Cancel() error {
return DnsCancelQuery(&i.cancel) return DnsCancelQuery(&i.cancel)
} }
func DnsQuery(qname string, qtype uint16, qoptions uint64, srvList *DNSServerList, interfaceIdx uint32) (*DNSQueryResult, error) { type DNSResult interface {
inv, err := newDnsInvoker(qname, qtype, qoptions, srvList, interfaceIdx) Wait() *DNSQueryResult
Cancel() error
}
func DNSQuery(qname string, qtype uint16, qoptions uint64, srvList *DNSServerList, interfaceIdx uint32) (DNSResult, error) {
inv, err := newDNSInvoker(qname, qtype, qoptions, srvList, interfaceIdx)
if err != nil { if err != nil {
return nil, fmt.Errorf("Failed creating DNS invoker: %w", err) return nil, fmt.Errorf("Failed creating DNS invoker: %w", err)
} }
@ -106,6 +112,5 @@ func DnsQuery(qname string, qtype uint16, qoptions uint64, srvList *DNSServerLis
return nil, fmt.Errorf("Failed submitting work: %w", err) return nil, fmt.Errorf("Failed submitting work: %w", err)
} }
inv.Wait() return inv, nil
return &inv.result, nil
} }