mapper: produce map before poll (#2628)

hscontrol/util/dns_test.go

@@ -5,6 +5,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"tailscale.com/util/dnsname"
+	"tailscale.com/util/must"
 )
 
 func TestCheckForFQDNRules(t *testing.T) {
@@ -102,59 +104,16 @@ func TestConvertWithFQDNRules(t *testing.T) {
 func TestMagicDNSRootDomains100(t *testing.T) {
 	domains := GenerateIPv4DNSRootDomain(netip.MustParsePrefix("100.64.0.0/10"))
 
-	found := false
-	for _, domain := range domains {
-		if domain == "64.100.in-addr.arpa." {
-			found = true
-
-			break
-		}
-	}
-	assert.True(t, found)
-
-	found = false
-	for _, domain := range domains {
-		if domain == "100.100.in-addr.arpa." {
-			found = true
-
-			break
-		}
-	}
-	assert.True(t, found)
-
-	found = false
-	for _, domain := range domains {
-		if domain == "127.100.in-addr.arpa." {
-			found = true
-
-			break
-		}
-	}
-	assert.True(t, found)
+	assert.Contains(t, domains, must.Get(dnsname.ToFQDN("64.100.in-addr.arpa.")))
+	assert.Contains(t, domains, must.Get(dnsname.ToFQDN("100.100.in-addr.arpa.")))
+	assert.Contains(t, domains, must.Get(dnsname.ToFQDN("127.100.in-addr.arpa.")))
 }
 
 func TestMagicDNSRootDomains172(t *testing.T) {
 	domains := GenerateIPv4DNSRootDomain(netip.MustParsePrefix("172.16.0.0/16"))
 
-	found := false
-	for _, domain := range domains {
-		if domain == "0.16.172.in-addr.arpa." {
-			found = true
-
-			break
-		}
-	}
-	assert.True(t, found)
-
-	found = false
-	for _, domain := range domains {
-		if domain == "255.16.172.in-addr.arpa." {
-			found = true
-
-			break
-		}
-	}
-	assert.True(t, found)
+	assert.Contains(t, domains, must.Get(dnsname.ToFQDN("0.16.172.in-addr.arpa.")))
+	assert.Contains(t, domains, must.Get(dnsname.ToFQDN("255.16.172.in-addr.arpa.")))
 }
 
 // Happens when netmask is a multiple of 4 bits (sounds likely).

hscontrol/util/util.go

@@ -143,7 +143,7 @@ func ParseTraceroute(output string) (Traceroute, error) {
 
 		// Parse latencies
 		for j := 5; j <= 7; j++ {
-			if matches[j] != "" {
+			if j < len(matches) && matches[j] != "" {
 				ms, err := strconv.ParseFloat(matches[j], 64)
 				if err != nil {
 					return Traceroute{}, fmt.Errorf("parsing latency: %w", err)