Use powershell Resolve-DnsName -Name <name> to verify DNS on Windows.

The `nslookup` used before this commit, does not use the DNS information
provided by the OS, and hence is not a good choice for validating that
our local DNS server is functional.

Signed-off-by: Thomas Hallgren <[email protected]>

Author: thallgren

pkg/client/userd/trafficmgr/intercept.go

@@ -732,12 +732,12 @@ func (s *session) InterceptEpilog(context.Context, *rpc.CreateInterceptRequest,
 }
 
 func waitForDNS(c context.Context, host string) bool {
-	c, cancel := context.WithTimeout(c, 5*time.Second)
+	c, cancel := context.WithTimeout(c, 12*time.Second)
 	defer cancel()
 	for c.Err() == nil {
 		dtime.SleepWithContext(c, 200*time.Millisecond)
 		dlog.Debugf(c, "Attempting to resolve DNS for %s", host)
-		ips := dnsproxy.TimedExternalLookup(c, host, 3*time.Second)
+		ips := dnsproxy.TimedExternalLookup(c, host, 5*time.Second)
 		if len(ips) > 0 {
 			dlog.Debugf(c, "Attempt succeeded, DNS for %s is %v", host, ips)
 			return true

pkg/dnsproxy/lookup_windows.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"fmt"
 	"strings"
 	"time"
 
@@ -14,39 +15,17 @@ import (
 func externalLookup(ctx context.Context, host string, timeout time.Duration) iputil.IPs {
 	ctx, cancel := context.WithTimeout(ctx, timeout)
 	defer cancel()
-	cmd := proc.CommandContext(ctx, "nslookup", host)
+	cmd := proc.CommandContext(ctx, "powershell.exe", "-NoProfile", "-NonInteractive", fmt.Sprintf("(Resolve-DnsName -Name %s -Type A_AAAA -DnsOnly).IPAddress", host))
 	cmd.DisableLogging = true
 	out, err := cmd.Output()
 	if err != nil {
 		return nil
 	}
-
-	// Look for the adjacent lines
-	//   Name: <host> [possibly extended with search path]
-	//   Address: <ip>
 	var ips iputil.IPs
 	sc := bufio.NewScanner(bytes.NewReader(out))
 	for sc.Scan() {
-		s := sc.Text()
-		if a := strings.TrimPrefix(s, "Name:"); a != s && strings.HasPrefix(strings.TrimSpace(a), host) && sc.Scan() {
-			s = sc.Text()
-			if a := strings.TrimPrefix(s, "Address:"); a != s {
-				if ip := iputil.Parse(strings.TrimSpace(a)); ip != nil {
-					ips = append(ips, ip)
-				}
-			} else if a := strings.TrimPrefix(s, "Addresses:"); a != s {
-				for {
-					if ip := iputil.Parse(strings.TrimSpace(a)); ip != nil {
-						ips = append(ips, ip)
-					} else {
-						break
-					}
-					if !sc.Scan() {
-						break
-					}
-					a = sc.Text()
-				}
-			}
+		if ip := iputil.Parse(strings.TrimSpace(sc.Text())); ip != nil {
+			ips = append(ips, ip)
 		}
 	}
 	return ips

pkg/vif/device_windows.go

@@ -237,7 +237,7 @@ func getGlobalSearchList() ([]string, error) {
 }
 
 func setGlobalSearchList(ctx context.Context, gss []string) error {
-	cmd := proc.CommandContext(ctx, "powershell.exe", "Set-DnsClientGlobalSetting", "-SuffixSearchList", psList(gss))
+	cmd := proc.CommandContext(ctx, "powershell.exe", "-NoProfile", "-NonInteractive", "Set-DnsClientGlobalSetting", "-SuffixSearchList", psList(gss))
 	_, err := proc.CaptureErr(ctx, cmd)
 	return err
 }