Merge pull request #34 from openshift-cherrypick-robot/cherry-pick-24…

…-to-release-4.7

Bug 1983695: [release-4.7] Truncate long service names to 63 characters

pkg/publisher/publisher.go

@@ -1,6 +1,7 @@
 package publisher
 
 import (
+	"crypto/sha256"
 	"fmt"
 	"net"
 	"sync"
@@ -14,7 +15,8 @@ var log = logrus.New()
 
 func Publish(ip net.IP, iface net.Interface, service Service, shutdown chan struct{}, waitGroup *sync.WaitGroup) (err error) {
 	defer waitGroup.Done()
-	svcEntry := zeroconf.NewServiceEntry(service.Name, service.SvcType, service.Domain)
+	svcName := truncateLongServiceName(service.Name)
+	svcEntry := zeroconf.NewServiceEntry(svcName, service.SvcType, service.Domain)
 	svcEntry.Port = service.Port
 	if ip.To4() != nil {
 		svcEntry.AddrIPv4 = append(svcEntry.AddrIPv4, ip)
@@ -105,6 +107,22 @@ func SetLogLevel(level logrus.Level) {
 	log.SetLevel(level)
 }
 
+// Service names cannot be longer than 63 characters. If we get a service name
+// that is longer, hash it to 32 characters, and sandwich that between the
+// first 15 and last 16 characters of the original name. This way we preserve
+// the likely unique parts of the name while ensuring it does not exceed
+// the 63 character limit.
+func truncateLongServiceName(serviceName string) (svcName string) {
+	svcName = serviceName
+	if len(svcName) > 63 {
+		value := sha256.Sum256([]byte(svcName))
+		hexValue := fmt.Sprintf("%x", value)[:32]
+		svcName = svcName[:15] + string(hexValue[:]) + svcName[len(svcName)-16:]
+		log.Printf("Truncating long service name '%s' to '%s'", serviceName, svcName)
+	}
+	return svcName
+}
+
 // networkInterfacer defines an interface for several net library functions. Production
 // code will forward to net library functions, and unit tests will override the methods
 // for testing purposes.

pkg/publisher/publisher_test.go

@@ -163,3 +163,23 @@ func (networkInterfaceWithInvalidAddr) Addrs(intf *net.Interface) ([]net.Addr, e
 func (networkInterfaceWithInvalidAddr) Interfaces() ([]net.Interface, error) {
 	return []net.Interface{upIntf}, nil
 }
+
+func TestLongNameTruncation(t *testing.T) {
+	testCases := []struct {
+		tcase    string
+		name     string
+		expected string
+	}{
+		{"short name", "master-0", "master-0"},
+		{"long name", "prefix-someverylongservicenamethatwouldcauseaproblemfordns-suffix", "prefix-somevery47540ff49304816bc5054bb4f3cc9a9clemfordns-suffix"},
+	}
+	for _, tc := range testCases {
+		result := truncateLongServiceName(tc.name)
+		if result != tc.expected {
+			t.Errorf("case[%v]: expected %v, got %v", tc.tcase, tc.expected, result)
+		}
+		if len(result) > 63 {
+			t.Errorf("case[%v]: Truncated name too long: '%v' is %d characters long", tc.tcase, result, len(result))
+		}
+	}
+}