Use hex.Dump for Layer.String() of byte slices.

PiperOrigin-RevId: 306726587

2 files changed, 21 insertions, 3 deletions

diff --git a/test/packetimpact/testbench/layers.go b/test/packetimpact/testbench/layers.go
index 1ec94ce17..5ce324f0d 100644
--- a/test/packetimpact/testbench/layers.go
+++ b/test/packetimpact/testbench/layers.go
@@ -15,6 +15,7 @@
 package testbench
 
 import (
+	"encoding/hex"
 	"fmt"
 	"reflect"
 	"strings"
@@ -133,7 +134,12 @@ func stringLayer(l Layer) string {
 		if v.IsNil() {
 			continue
 		}
-		ret = append(ret, fmt.Sprintf("%s:%v", t.Name, reflect.Indirect(v)))
+		v = reflect.Indirect(v)
+		if v.Kind() == reflect.Slice && v.Type().Elem().Kind() == reflect.Uint8 {
+			ret = append(ret, fmt.Sprintf("%s:\n%v", t.Name, hex.Dump(v.Bytes())))
+		} else {
+			ret = append(ret, fmt.Sprintf("%s:%v", t.Name, v))
+		}
 	}
 	return fmt.Sprintf("&%s{%s}", t, strings.Join(ret, " "))
 }
diff --git a/test/packetimpact/testbench/layers_test.go b/test/packetimpact/testbench/layers_test.go
index 8ffc26bf9..b32efda93 100644
--- a/test/packetimpact/testbench/layers_test.go
+++ b/test/packetimpact/testbench/layers_test.go
@@ -14,9 +14,11 @@
 
 package testbench
 
-import "testing"
+import (
+	"testing"
 
-import "gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
 
 func TestLayerMatch(t *testing.T) {
 	var nilPayload *Payload
@@ -134,6 +136,16 @@ func TestLayerStringFormat(t *testing.T) {
 				"Type:4" +
 				"}",
 		},
+		{
+			name: "Payload",
+			l: &Payload{
+				Bytes: []byte("Hooray for packetimpact."),
+			},
+			want: "&testbench.Payload{Bytes:\n" +
+				"00000000  48 6f 6f 72 61 79 20 66  6f 72 20 70 61 63 6b 65  |Hooray for packe|\n" +
+				"00000010  74 69 6d 70 61 63 74 2e                           |timpact.|\n" +
+				"}",
+		},
 	} {
 		t.Run(tt.name, func(t *testing.T) {
 			if got := tt.l.String(); got != tt.want {