Use nicer formatting for IP addresses in tests

This was semi-automated -- there are many addresses that were not replaced.
Future commits should clean those up.

Parse4 and Parse6 were given their own package because //pkg/test can introduce
dependency cycles, as it depends transitively on //pkg/tcpip and some other
netstack packages.

PiperOrigin-RevId: 368726528

33 files changed, 334 insertions, 117 deletions

diff --git a/pkg/tcpip/header/BUILD b/pkg/tcpip/header/BUILD
index 0bdc12d53..01240f5d0 100644
--- a/pkg/tcpip/header/BUILD
+++ b/pkg/tcpip/header/BUILD
@@ -52,6 +52,7 @@ go_test(
         "//pkg/rand",
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
+        "//pkg/tcpip/testutil",
         "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
@@ -69,6 +70,7 @@ go_test(
     deps = [
         "//pkg/tcpip",
         "//pkg/tcpip/buffer",
+        "//pkg/tcpip/testutil",
         "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/tcpip/header/eth_test.go b/pkg/tcpip/header/eth_test.go
index 3bc8b2b21..bf9ccbf1a 100644
--- a/pkg/tcpip/header/eth_test.go
+++ b/pkg/tcpip/header/eth_test.go
@@ -18,6 +18,7 @@ import (
 	"testing"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 func TestIsValidUnicastEthernetAddress(t *testing.T) {
@@ -142,7 +143,7 @@ func TestEthernetAddressFromMulticastIPv4Address(t *testing.T) {
 }
 
 func TestEthernetAddressFromMulticastIPv6Address(t *testing.T) {
-	addr := tcpip.Address("\xff\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x1a")
+	addr := testutil.MustParse6("ff02:304:506:708:90a:b0c:d0e:f1a")
 	if got, want := EthernetAddressFromMulticastIPv6Address(addr), tcpip.LinkAddress("\x33\x33\x0d\x0e\x0f\x1a"); got != want {
 		t.Fatalf("got EthernetAddressFromMulticastIPv6Address(%s) = %s, want = %s", addr, got, want)
 	}
diff --git a/pkg/tcpip/header/igmp_test.go b/pkg/tcpip/header/igmp_test.go
index b6126d29a..575604928 100644
--- a/pkg/tcpip/header/igmp_test.go
+++ b/pkg/tcpip/header/igmp_test.go
@@ -18,8 +18,8 @@ import (
 	"testing"
 	"time"
 
-	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 // TestIGMPHeader tests the functions within header.igmp
@@ -46,7 +46,7 @@ func TestIGMPHeader(t *testing.T) {
 		t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, want)
 	}
 
-	if got, want := igmpHeader.GroupAddress(), tcpip.Address("\x01\x02\x03\x04"); got != want {
+	if got, want := igmpHeader.GroupAddress(), testutil.MustParse4("1.2.3.4"); got != want {
 		t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, want)
 	}
 
@@ -71,7 +71,7 @@ func TestIGMPHeader(t *testing.T) {
 		t.Errorf("got igmpHeader.Checksum() = %x, want = %x", got, checksum)
 	}
 
-	groupAddress := tcpip.Address("\x04\x03\x02\x01")
+	groupAddress := testutil.MustParse4("4.3.2.1")
 	igmpHeader.SetGroupAddress(groupAddress)
 	if got := igmpHeader.GroupAddress(); got != groupAddress {
 		t.Errorf("got igmpHeader.GroupAddress() = %s, want = %s", got, groupAddress)
diff --git a/pkg/tcpip/header/ipv6_test.go b/pkg/tcpip/header/ipv6_test.go
index ccee9000e..89be84068 100644
--- a/pkg/tcpip/header/ipv6_test.go
+++ b/pkg/tcpip/header/ipv6_test.go
@@ -24,15 +24,17 @@ import (
 	"gvisor.dev/gvisor/pkg/rand"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
-const (
-	linkAddr               = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
-	linkLocalAddr          = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	linkLocalMulticastAddr = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	uniqueLocalAddr1       = tcpip.Address("\xfc\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	uniqueLocalAddr2       = tcpip.Address("\xfd\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-	globalAddr             = tcpip.Address("\xa0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
+const linkAddr = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
+
+var (
+	linkLocalAddr          = testutil.MustParse6("fe80::1")
+	linkLocalMulticastAddr = testutil.MustParse6("ff02::1")
+	uniqueLocalAddr1       = testutil.MustParse6("fc00::1")
+	uniqueLocalAddr2       = testutil.MustParse6("fd00::2")
+	globalAddr             = testutil.MustParse6("a000::1")
 )
 
 func TestEthernetAdddressToModifiedEUI64(t *testing.T) {
@@ -50,7 +52,7 @@ func TestEthernetAdddressToModifiedEUI64(t *testing.T) {
 }
 
 func TestLinkLocalAddr(t *testing.T) {
-	if got, want := header.LinkLocalAddr(linkAddr), tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x02\x03\xff\xfe\x04\x05\x06"); got != want {
+	if got, want := header.LinkLocalAddr(linkAddr), testutil.MustParse6("fe80::2:3ff:fe04:506"); got != want {
 		t.Errorf("got LinkLocalAddr(%s) = %s, want = %s", linkAddr, got, want)
 	}
 }
diff --git a/pkg/tcpip/header/ndp_test.go b/pkg/tcpip/header/ndp_test.go
index d0a1a2492..1b5093e58 100644
--- a/pkg/tcpip/header/ndp_test.go
+++ b/pkg/tcpip/header/ndp_test.go
@@ -26,6 +26,7 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 // TestNDPNeighborSolicit tests the functions of NDPNeighborSolicit.
@@ -40,13 +41,13 @@ func TestNDPNeighborSolicit(t *testing.T) {
 
 	// Test getting the Target Address.
 	ns := NDPNeighborSolicit(b)
-	addr := tcpip.Address("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10")
+	addr := testutil.MustParse6("102:304:506:708:90a:b0c:d0e:f10")
 	if got := ns.TargetAddress(); got != addr {
 		t.Errorf("got ns.TargetAddress = %s, want %s", got, addr)
 	}
 
 	// Test updating the Target Address.
-	addr2 := tcpip.Address("\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x11")
+	addr2 := testutil.MustParse6("1112:1314:1516:1718:191a:1b1c:1d1e:1f11")
 	ns.SetTargetAddress(addr2)
 	if got := ns.TargetAddress(); got != addr2 {
 		t.Errorf("got ns.TargetAddress = %s, want %s", got, addr2)
@@ -69,7 +70,7 @@ func TestNDPNeighborAdvert(t *testing.T) {
 
 	// Test getting the Target Address.
 	na := NDPNeighborAdvert(b)
-	addr := tcpip.Address("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10")
+	addr := testutil.MustParse6("102:304:506:708:90a:b0c:d0e:f10")
 	if got := na.TargetAddress(); got != addr {
 		t.Errorf("got TargetAddress = %s, want %s", got, addr)
 	}
@@ -90,7 +91,7 @@ func TestNDPNeighborAdvert(t *testing.T) {
 	}
 
 	// Test updating the Target Address.
-	addr2 := tcpip.Address("\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x11")
+	addr2 := testutil.MustParse6("1112:1314:1516:1718:191a:1b1c:1d1e:1f11")
 	na.SetTargetAddress(addr2)
 	if got := na.TargetAddress(); got != addr2 {
 		t.Errorf("got TargetAddress = %s, want %s", got, addr2)
@@ -277,7 +278,7 @@ func TestOpts(t *testing.T) {
 	}
 
 	const validLifetimeSeconds = 16909060
-	const address = tcpip.Address("\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18")
+	address := testutil.MustParse6("90a:b0c:d0e:f10:1112:1314:1516:1718")
 
 	expectedRDNSSBytes := [...]byte{
 		// Type, Length
diff --git a/pkg/tcpip/network/BUILD b/pkg/tcpip/network/BUILD
index fa8814bac..7b1ff44f4 100644
--- a/pkg/tcpip/network/BUILD
+++ b/pkg/tcpip/network/BUILD
@@ -21,6 +21,7 @@ go_test(
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/tcp",
         "//pkg/tcpip/transport/udp",
diff --git a/pkg/tcpip/network/arp/BUILD b/pkg/tcpip/network/arp/BUILD
index d59d678b2..6905b9ccb 100644
--- a/pkg/tcpip/network/arp/BUILD
+++ b/pkg/tcpip/network/arp/BUILD
@@ -33,6 +33,7 @@ go_test(
         "//pkg/tcpip/link/sniffer",
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "@com_github_google_go_cmp//cmp:go_default_library",
         "@com_github_google_go_cmp//cmp/cmpopts:go_default_library",
diff --git a/pkg/tcpip/network/arp/arp_test.go b/pkg/tcpip/network/arp/arp_test.go
index 018d6a578..9b3714f9e 100644
--- a/pkg/tcpip/network/arp/arp_test.go
+++ b/pkg/tcpip/network/arp/arp_test.go
@@ -30,20 +30,16 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/arp"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 )
 
 const (
 	nicID = 1
 
-	stackAddr     = tcpip.Address("\x0a\x00\x00\x01")
-	stackLinkAddr = tcpip.LinkAddress("\x0a\x0a\x0b\x0b\x0c\x0c")
-
-	remoteAddr     = tcpip.Address("\x0a\x00\x00\x02")
+	stackLinkAddr  = tcpip.LinkAddress("\x0a\x0a\x0b\x0b\x0c\x0c")
 	remoteLinkAddr = tcpip.LinkAddress("\x01\x02\x03\x04\x05\x06")
 
-	unknownAddr = tcpip.Address("\x0a\x00\x00\x03")
-
 	defaultChannelSize = 1
 	defaultMTU         = 65536
 
@@ -54,6 +50,12 @@ const (
 	eventChanSize = 32
 )
 
+var (
+	stackAddr   = testutil.MustParse4("10.0.0.1")
+	remoteAddr  = testutil.MustParse4("10.0.0.2")
+	unknownAddr = testutil.MustParse4("10.0.0.3")
+)
+
 type eventType uint8
 
 const (
diff --git a/pkg/tcpip/network/ip_test.go b/pkg/tcpip/network/ip_test.go
index 58fd18af8..dbd674634 100644
--- a/pkg/tcpip/network/ip_test.go
+++ b/pkg/tcpip/network/ip_test.go
@@ -30,23 +30,25 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 )
 
-const (
-	localIPv4Addr  = tcpip.Address("\x0a\x00\x00\x01")
-	remoteIPv4Addr = tcpip.Address("\x0a\x00\x00\x02")
-	ipv4SubnetAddr = tcpip.Address("\x0a\x00\x00\x00")
-	ipv4SubnetMask = tcpip.Address("\xff\xff\xff\x00")
-	ipv4Gateway    = tcpip.Address("\x0a\x00\x00\x03")
-	localIPv6Addr  = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	remoteIPv6Addr = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-	ipv6SubnetAddr = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
-	ipv6SubnetMask = tcpip.Address("\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00")
-	ipv6Gateway    = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03")
-	nicID          = 1
+const nicID = 1
+
+var (
+	localIPv4Addr  = testutil.MustParse4("10.0.0.1")
+	remoteIPv4Addr = testutil.MustParse4("10.0.0.2")
+	ipv4SubnetAddr = testutil.MustParse4("10.0.0.0")
+	ipv4SubnetMask = testutil.MustParse4("255.255.255.0")
+	ipv4Gateway    = testutil.MustParse4("10.0.0.3")
+	localIPv6Addr  = testutil.MustParse6("a00::1")
+	remoteIPv6Addr = testutil.MustParse6("a00::2")
+	ipv6SubnetAddr = testutil.MustParse6("a00::")
+	ipv6SubnetMask = testutil.MustParse6("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ff00")
+	ipv6Gateway    = testutil.MustParse6("a00::3")
 )
 
 var localIPv4AddrWithPrefix = tcpip.AddressWithPrefix{
diff --git a/pkg/tcpip/network/ipv4/BUILD b/pkg/tcpip/network/ipv4/BUILD
index 5e7f10f4b..7ee0495d9 100644
--- a/pkg/tcpip/network/ipv4/BUILD
+++ b/pkg/tcpip/network/ipv4/BUILD
@@ -45,6 +45,7 @@ go_test(
         "//pkg/tcpip/network/internal/testutil",
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/raw",
         "//pkg/tcpip/transport/tcp",
diff --git a/pkg/tcpip/network/ipv4/igmp_test.go b/pkg/tcpip/network/ipv4/igmp_test.go
index e5e1b89cc..4bd6f462e 100644
--- a/pkg/tcpip/network/ipv4/igmp_test.go
+++ b/pkg/tcpip/network/ipv4/igmp_test.go
@@ -26,18 +26,22 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 const (
 	linkAddr            = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
-	stackAddr           = tcpip.Address("\x0a\x00\x00\x01")
-	remoteAddr          = tcpip.Address("\x0a\x00\x00\x02")
-	multicastAddr       = tcpip.Address("\xe0\x00\x00\x03")
 	nicID               = 1
 	defaultTTL          = 1
 	defaultPrefixLength = 24
 )
 
+var (
+	stackAddr     = testutil.MustParse4("10.0.0.1")
+	remoteAddr    = testutil.MustParse4("10.0.0.2")
+	multicastAddr = testutil.MustParse4("224.0.0.3")
+)
+
 // validateIgmpPacket checks that a passed PacketInfo is an IPv4 IGMP packet
 // sent to the provided address with the passed fields set. Raises a t.Error if
 // any field does not match.
@@ -292,7 +296,7 @@ func TestIGMPPacketValidation(t *testing.T) {
 			messageType:              header.IGMPLeaveGroup,
 			includeRouterAlertOption: true,
 			stackAddresses:           []tcpip.AddressWithPrefix{{Address: stackAddr, PrefixLen: 24}},
-			srcAddr:                  tcpip.Address("\x0a\x00\x01\x02"),
+			srcAddr:                  testutil.MustParse4("10.0.1.2"),
 			ttl:                      1,
 			expectValidIGMP:          false,
 			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.IGMP.PacketsReceived.LeaveGroup.Value() },
@@ -302,7 +306,7 @@ func TestIGMPPacketValidation(t *testing.T) {
 			messageType:              header.IGMPMembershipQuery,
 			includeRouterAlertOption: true,
 			stackAddresses:           []tcpip.AddressWithPrefix{{Address: stackAddr, PrefixLen: 24}},
-			srcAddr:                  tcpip.Address("\x0a\x00\x01\x02"),
+			srcAddr:                  testutil.MustParse4("10.0.1.2"),
 			ttl:                      1,
 			expectValidIGMP:          true,
 			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.IGMP.PacketsReceived.MembershipQuery.Value() },
@@ -312,7 +316,7 @@ func TestIGMPPacketValidation(t *testing.T) {
 			messageType:              header.IGMPv1MembershipReport,
 			includeRouterAlertOption: true,
 			stackAddresses:           []tcpip.AddressWithPrefix{{Address: stackAddr, PrefixLen: 24}},
-			srcAddr:                  tcpip.Address("\x0a\x00\x01\x02"),
+			srcAddr:                  testutil.MustParse4("10.0.1.2"),
 			ttl:                      1,
 			expectValidIGMP:          false,
 			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.IGMP.PacketsReceived.V1MembershipReport.Value() },
@@ -322,7 +326,7 @@ func TestIGMPPacketValidation(t *testing.T) {
 			messageType:              header.IGMPv2MembershipReport,
 			includeRouterAlertOption: true,
 			stackAddresses:           []tcpip.AddressWithPrefix{{Address: stackAddr, PrefixLen: 24}},
-			srcAddr:                  tcpip.Address("\x0a\x00\x01\x02"),
+			srcAddr:                  testutil.MustParse4("10.0.1.2"),
 			ttl:                      1,
 			expectValidIGMP:          false,
 			getMessageTypeStatValue:  func(stats tcpip.Stats) uint64 { return stats.IGMP.PacketsReceived.V2MembershipReport.Value() },
@@ -332,7 +336,7 @@ func TestIGMPPacketValidation(t *testing.T) {
 			messageType:              header.IGMPv2MembershipReport,
 			includeRouterAlertOption: true,
 			stackAddresses: []tcpip.AddressWithPrefix{
-				{Address: tcpip.Address("\x0a\x00\x0f\x01"), PrefixLen: 24},
+				{Address: testutil.MustParse4("10.0.15.1"), PrefixLen: 24},
 				{Address: stackAddr, PrefixLen: 24},
 			},
 			srcAddr:                 remoteAddr,
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index 8e6e81005..d49dff4d5 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -39,6 +39,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/internal/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	tcptestutil "gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
@@ -3039,12 +3040,14 @@ func TestCloseLocking(t *testing.T) {
 		nicID1 = 1
 		nicID2 = 2
 
-		src = tcpip.Address("\x10\x00\x00\x01")
-		dst = tcpip.Address("\x10\x00\x00\x02")
-
 		iterations = 1000
 	)
 
+	var (
+		src = tcptestutil.MustParse4("16.0.0.1")
+		dst = tcptestutil.MustParse4("16.0.0.2")
+	)
+
 	s := stack.New(stack.Options{
 		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol},
 		TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
diff --git a/pkg/tcpip/network/ipv6/BUILD b/pkg/tcpip/network/ipv6/BUILD
index bb9a02ed0..db998e83e 100644
--- a/pkg/tcpip/network/ipv6/BUILD
+++ b/pkg/tcpip/network/ipv6/BUILD
@@ -66,5 +66,6 @@ go_test(
         "//pkg/tcpip/header",
         "//pkg/tcpip/link/channel",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
     ],
 )
diff --git a/pkg/tcpip/network/ipv6/mld_test.go b/pkg/tcpip/network/ipv6/mld_test.go
index 146b300f1..71d1c3e28 100644
--- a/pkg/tcpip/network/ipv6/mld_test.go
+++ b/pkg/tcpip/network/ipv6/mld_test.go
@@ -27,15 +27,14 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
-)
-
-const (
-	linkLocalAddr       = "\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"
-	globalAddr          = "\x0a\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"
-	globalMulticastAddr = "\xff\x05\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 var (
+	linkLocalAddr       = testutil.MustParse6("fe80::1")
+	globalAddr          = testutil.MustParse6("a80::1")
+	globalMulticastAddr = testutil.MustParse6("ff05:100::2")
+
 	linkLocalAddrSNMC = header.SolicitedNodeAddr(linkLocalAddr)
 	globalAddrSNMC    = header.SolicitedNodeAddr(globalAddr)
 )
@@ -354,10 +353,8 @@ func createAndInjectMLDPacket(e *channel.Endpoint, mldType header.ICMPv6Type, ho
 }
 
 func TestMLDPacketValidation(t *testing.T) {
-	const (
-		nicID          = 1
-		linkLocalAddr2 = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-	)
+	const nicID = 1
+	linkLocalAddr2 := testutil.MustParse6("fe80::2")
 
 	tests := []struct {
 		name                     string
diff --git a/pkg/tcpip/network/multicast_group_test.go b/pkg/tcpip/network/multicast_group_test.go
index 2aa4e6d75..1b96b1fb8 100644
--- a/pkg/tcpip/network/multicast_group_test.go
+++ b/pkg/tcpip/network/multicast_group_test.go
@@ -30,22 +30,13 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 const (
 	linkAddr = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
 
-	stackIPv4Addr           = tcpip.Address("\x0a\x00\x00\x01")
 	defaultIPv4PrefixLength = 24
-	linkLocalIPv6Addr1      = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	linkLocalIPv6Addr2      = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-
-	ipv4MulticastAddr1 = tcpip.Address("\xe0\x00\x00\x03")
-	ipv4MulticastAddr2 = tcpip.Address("\xe0\x00\x00\x04")
-	ipv4MulticastAddr3 = tcpip.Address("\xe0\x00\x00\x05")
-	ipv6MulticastAddr1 = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03")
-	ipv6MulticastAddr2 = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04")
-	ipv6MulticastAddr3 = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x05")
 
 	igmpMembershipQuery    = uint8(header.IGMPMembershipQuery)
 	igmpv1MembershipReport = uint8(header.IGMPv1MembershipReport)
@@ -59,6 +50,19 @@ const (
 )
 
 var (
+	stackIPv4Addr      = testutil.MustParse4("10.0.0.1")
+	linkLocalIPv6Addr1 = testutil.MustParse6("fe80::1")
+	linkLocalIPv6Addr2 = testutil.MustParse6("fe80::2")
+
+	ipv4MulticastAddr1 = testutil.MustParse4("224.0.0.3")
+	ipv4MulticastAddr2 = testutil.MustParse4("224.0.0.4")
+	ipv4MulticastAddr3 = testutil.MustParse4("224.0.0.5")
+	ipv6MulticastAddr1 = testutil.MustParse6("ff02::3")
+	ipv6MulticastAddr2 = testutil.MustParse6("ff02::4")
+	ipv6MulticastAddr3 = testutil.MustParse6("ff02::5")
+)
+
+var (
 	// unsolicitedIGMPReportIntervalMaxTenthSec is the maximum amount of time the
 	// NIC will wait before sending an unsolicited report after joining a
 	// multicast group, in deciseconds.
diff --git a/pkg/tcpip/ports/BUILD b/pkg/tcpip/ports/BUILD
index 210262703..b7f6d52ae 100644
--- a/pkg/tcpip/ports/BUILD
+++ b/pkg/tcpip/ports/BUILD
@@ -21,6 +21,7 @@ go_test(
     library = ":ports",
     deps = [
         "//pkg/tcpip",
+        "//pkg/tcpip/testutil",
         "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/tcpip/ports/ports_test.go b/pkg/tcpip/ports/ports_test.go
index 0f43dc8f8..5dfc5371a 100644
--- a/pkg/tcpip/ports/ports_test.go
+++ b/pkg/tcpip/ports/ports_test.go
@@ -20,14 +20,17 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 const (
 	fakeTransNumber   tcpip.TransportProtocolNumber = 1
 	fakeNetworkNumber tcpip.NetworkProtocolNumber   = 2
+)
 
-	fakeIPAddress  = tcpip.Address("\x08\x08\x08\x08")
-	fakeIPAddress1 = tcpip.Address("\x08\x08\x08\x09")
+var (
+	fakeIPAddress  = testutil.MustParse4("8.8.8.8")
+	fakeIPAddress1 = testutil.MustParse4("8.8.8.9")
 )
 
 type portReserveTestAction struct {
diff --git a/pkg/tcpip/stack/BUILD b/pkg/tcpip/stack/BUILD
index bbd75c73a..d19b879dc 100644
--- a/pkg/tcpip/stack/BUILD
+++ b/pkg/tcpip/stack/BUILD
@@ -116,6 +116,7 @@ go_test(
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/ports",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/udp",
         "//pkg/waiter",
@@ -140,6 +141,7 @@ go_test(
         "//pkg/tcpip/buffer",
         "//pkg/tcpip/faketime",
         "//pkg/tcpip/header",
+        "//pkg/tcpip/testutil",
         "@com_github_google_go_cmp//cmp:go_default_library",
         "@com_github_google_go_cmp//cmp/cmpopts:go_default_library",
     ],
diff --git a/pkg/tcpip/stack/ndp_test.go b/pkg/tcpip/stack/ndp_test.go
index a869cce38..b6cf24739 100644
--- a/pkg/tcpip/stack/ndp_test.go
+++ b/pkg/tcpip/stack/ndp_test.go
@@ -33,15 +33,19 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 	"gvisor.dev/gvisor/pkg/waiter"
 )
 
+var (
+	addr1 = testutil.MustParse6("a00::1")
+	addr2 = testutil.MustParse6("a00::2")
+	addr3 = testutil.MustParse6("a00::3")
+)
+
 const (
-	addr1     = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	addr2     = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-	addr3     = tcpip.Address("\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03")
 	linkAddr1 = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
 	linkAddr2 = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x07")
 	linkAddr3 = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x08")
@@ -1390,7 +1394,7 @@ func TestRouterDiscoveryMaxRouters(t *testing.T) {
 // configured not to.
 func TestNoPrefixDiscovery(t *testing.T) {
 	prefix := tcpip.AddressWithPrefix{
-		Address:   tcpip.Address("\x01\x02\x03\x04\x05\x06\x07\x08\x00\x00\x00\x00\x00\x00\x00\x00"),
+		Address:   testutil.MustParse6("102:304:506:708::"),
 		PrefixLen: 64,
 	}
 
@@ -1590,7 +1594,7 @@ func TestPrefixDiscoveryWithInfiniteLifetime(t *testing.T) {
 	}()
 
 	prefix := tcpip.AddressWithPrefix{
-		Address:   tcpip.Address("\x01\x02\x03\x04\x05\x06\x07\x08\x00\x00\x00\x00\x00\x00\x00\x00"),
+		Address:   testutil.MustParse6("102:304:506:708::"),
 		PrefixLen: 64,
 	}
 	subnet := prefix.Subnet()
diff --git a/pkg/tcpip/stack/neighbor_entry_test.go b/pkg/tcpip/stack/neighbor_entry_test.go
index bb2b2d705..1d39ee73d 100644
--- a/pkg/tcpip/stack/neighbor_entry_test.go
+++ b/pkg/tcpip/stack/neighbor_entry_test.go
@@ -26,14 +26,13 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/faketime"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 )
 
 const (
 	entryTestNetNumber tcpip.NetworkProtocolNumber = math.MaxUint32
 
 	entryTestNICID tcpip.NICID = 1
-	entryTestAddr1             = tcpip.Address("\x00\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-	entryTestAddr2             = tcpip.Address("\x00\x0a\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
 
 	entryTestLinkAddr1 = tcpip.LinkAddress("\x0a\x00\x00\x00\x00\x01")
 	entryTestLinkAddr2 = tcpip.LinkAddress("\x0a\x00\x00\x00\x00\x02")
@@ -44,6 +43,11 @@ const (
 	entryTestNetDefaultMTU = 65536
 )
 
+var (
+	entryTestAddr1 = testutil.MustParse6("a::1")
+	entryTestAddr2 = testutil.MustParse6("a::2")
+)
+
 // runImmediatelyScheduledJobs runs all jobs scheduled to run at the current
 // time.
 func runImmediatelyScheduledJobs(clock *faketime.ManualClock) {
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index 2814b94b4..d99d2a163 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -39,6 +39,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 )
 
@@ -1645,10 +1646,10 @@ func TestOutgoingBroadcastWithRouteTable(t *testing.T) {
 	defaultAddr := tcpip.AddressWithPrefix{header.IPv4Any, 0}
 	// Local subnet on NIC1: 192.168.1.58/24, gateway 192.168.1.1.
 	nic1Addr := tcpip.AddressWithPrefix{"\xc0\xa8\x01\x3a", 24}
-	nic1Gateway := tcpip.Address("\xc0\xa8\x01\x01")
+	nic1Gateway := testutil.MustParse4("192.168.1.1")
 	// Local subnet on NIC2: 10.10.10.5/24, gateway 10.10.10.1.
 	nic2Addr := tcpip.AddressWithPrefix{"\x0a\x0a\x0a\x05", 24}
-	nic2Gateway := tcpip.Address("\x0a\x0a\x0a\x01")
+	nic2Gateway := testutil.MustParse4("10.10.10.1")
 
 	// Create a new stack with two NICs.
 	s := stack.New(stack.Options{
@@ -2789,25 +2790,27 @@ func TestNewPEBOnPromotionToPermanent(t *testing.T) {
 
 func TestIPv6SourceAddressSelectionScopeAndSameAddress(t *testing.T) {
 	const (
-		linkLocalAddr1         = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		linkLocalAddr2         = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-		linkLocalMulticastAddr = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		uniqueLocalAddr1       = tcpip.Address("\xfc\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		uniqueLocalAddr2       = tcpip.Address("\xfd\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-		globalAddr1            = tcpip.Address("\xa0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		globalAddr2            = tcpip.Address("\xa0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-		globalAddr3            = tcpip.Address("\xa0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x03")
-		ipv4MappedIPv6Addr1    = tcpip.Address("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x01")
-		ipv4MappedIPv6Addr2    = tcpip.Address("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x02")
-		toredoAddr1            = tcpip.Address("\x20\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		toredoAddr2            = tcpip.Address("\x20\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-		ipv6ToIPv4Addr1        = tcpip.Address("\x20\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01")
-		ipv6ToIPv4Addr2        = tcpip.Address("\x20\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02")
-
 		nicID           = 1
 		lifetimeSeconds = 9999
 	)
 
+	var (
+		linkLocalAddr1         = testutil.MustParse6("fe80::1")
+		linkLocalAddr2         = testutil.MustParse6("fe80::2")
+		linkLocalMulticastAddr = testutil.MustParse6("ff02::1")
+		uniqueLocalAddr1       = testutil.MustParse6("fc00::1")
+		uniqueLocalAddr2       = testutil.MustParse6("fd00::2")
+		globalAddr1            = testutil.MustParse6("a000::1")
+		globalAddr2            = testutil.MustParse6("a000::2")
+		globalAddr3            = testutil.MustParse6("a000::3")
+		ipv4MappedIPv6Addr1    = testutil.MustParse6("::ffff:0.0.0.1")
+		ipv4MappedIPv6Addr2    = testutil.MustParse6("::ffff:0.0.0.2")
+		toredoAddr1            = testutil.MustParse6("2001::1")
+		toredoAddr2            = testutil.MustParse6("2001::2")
+		ipv6ToIPv4Addr1        = testutil.MustParse6("2002::1")
+		ipv6ToIPv4Addr2        = testutil.MustParse6("2002::2")
+	)
+
 	prefix1, _, stableGlobalAddr1 := prefixSubnetAddr(0, linkAddr1)
 	prefix2, _, stableGlobalAddr2 := prefixSubnetAddr(1, linkAddr1)
 
@@ -3448,7 +3451,7 @@ func TestOutgoingSubnetBroadcast(t *testing.T) {
 	}
 	ipv4Subnet := ipv4Addr.Subnet()
 	ipv4SubnetBcast := ipv4Subnet.Broadcast()
-	ipv4Gateway := tcpip.Address("\xc0\xa8\x01\x01")
+	ipv4Gateway := testutil.MustParse4("192.168.1.1")
 	ipv4AddrPrefix31 := tcpip.AddressWithPrefix{
 		Address:   "\xc0\xa8\x01\x3a",
 		PrefixLen: 31,
@@ -4352,13 +4355,15 @@ func TestWritePacketToRemote(t *testing.T) {
 
 func TestClearNeighborCacheOnNICDisable(t *testing.T) {
 	const (
-		nicID = 1
-
-		ipv4Addr = tcpip.Address("\x01\x02\x03\x04")
-		ipv6Addr = tcpip.Address("\x01\x02\x03\x04\x01\x02\x03\x04\x01\x02\x03\x04\x01\x02\x03\x04")
+		nicID    = 1
 		linkAddr = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
 	)
 
+	var (
+		ipv4Addr = testutil.MustParse4("1.2.3.4")
+		ipv6Addr = testutil.MustParse6("102:304:102:304:102:304:102:304")
+	)
+
 	clock := faketime.NewManualClock()
 	s := stack.New(stack.Options{
 		NetworkProtocols: []stack.NetworkProtocolFactory{arp.NewProtocol, ipv4.NewProtocol, ipv6.NewProtocol},
diff --git a/pkg/tcpip/tests/integration/BUILD b/pkg/tcpip/tests/integration/BUILD
index 3b51e4be0..d4f7bb5ff 100644
--- a/pkg/tcpip/tests/integration/BUILD
+++ b/pkg/tcpip/tests/integration/BUILD
@@ -16,6 +16,7 @@ go_test(
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/tests/utils",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/tcp",
         "//pkg/tcpip/transport/udp",
         "//pkg/waiter",
@@ -80,6 +81,7 @@ go_test(
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/tests/utils",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/tcp",
         "//pkg/tcpip/transport/udp",
@@ -103,6 +105,7 @@ go_test(
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/tests/utils",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/udp",
         "//pkg/waiter",
@@ -125,6 +128,7 @@ go_test(
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/tests/utils",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/tcpip/transport/udp",
         "//pkg/waiter",
diff --git a/pkg/tcpip/tests/integration/forward_test.go b/pkg/tcpip/tests/integration/forward_test.go
index 0de5079e8..dbd279c94 100644
--- a/pkg/tcpip/tests/integration/forward_test.go
+++ b/pkg/tcpip/tests/integration/forward_test.go
@@ -28,6 +28,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/tests/utils"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -319,16 +320,17 @@ func TestMulticastForwarding(t *testing.T) {
 	const (
 		nicID1 = 1
 		nicID2 = 2
+		ttl    = 64
+	)
 
-		ipv4LinkLocalUnicastAddr   = tcpip.Address("\xa9\xfe\x00\x0a")
-		ipv4LinkLocalMulticastAddr = tcpip.Address("\xe0\x00\x00\x0a")
-		ipv4GlobalMulticastAddr    = tcpip.Address("\xe0\x00\x01\x0a")
-
-		ipv6LinkLocalUnicastAddr   = tcpip.Address("\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0a")
-		ipv6LinkLocalMulticastAddr = tcpip.Address("\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0a")
-		ipv6GlobalMulticastAddr    = tcpip.Address("\xff\x0e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0a")
+	var (
+		ipv4LinkLocalUnicastAddr   = testutil.MustParse4("169.254.0.10")
+		ipv4LinkLocalMulticastAddr = testutil.MustParse4("224.0.0.10")
+		ipv4GlobalMulticastAddr    = testutil.MustParse4("224.0.1.10")
 
-		ttl = 64
+		ipv6LinkLocalUnicastAddr   = testutil.MustParse6("fe80::a")
+		ipv6LinkLocalMulticastAddr = testutil.MustParse6("ff02::a")
+		ipv6GlobalMulticastAddr    = testutil.MustParse6("ff0e::a")
 	)
 
 	rxICMPv4EchoRequest := func(e *channel.Endpoint, src, dst tcpip.Address) {
diff --git a/pkg/tcpip/tests/integration/loopback_test.go b/pkg/tcpip/tests/integration/loopback_test.go
index 82c2e11ab..b04169751 100644
--- a/pkg/tcpip/tests/integration/loopback_test.go
+++ b/pkg/tcpip/tests/integration/loopback_test.go
@@ -30,6 +30,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/tests/utils"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
@@ -510,11 +511,10 @@ func TestExternalLoopbackTraffic(t *testing.T) {
 		nicID1 = 1
 		nicID2 = 2
 
-		ipv4Loopback = tcpip.Address("\x7f\x00\x00\x01")
-
 		numPackets = 1
 		ttl        = 64
 	)
+	ipv4Loopback := testutil.MustParse4("127.0.0.1")
 
 	loopbackSourcedICMPv4 := func(e *channel.Endpoint) {
 		utils.RxICMPv4EchoRequest(e, ipv4Loopback, utils.Ipv4Addr.Address, ttl)
diff --git a/pkg/tcpip/tests/integration/multicast_broadcast_test.go b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
index 09ff3b892..2d0a6e6a7 100644
--- a/pkg/tcpip/tests/integration/multicast_broadcast_test.go
+++ b/pkg/tcpip/tests/integration/multicast_broadcast_test.go
@@ -29,6 +29,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/tests/utils"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -438,10 +439,10 @@ func TestIncomingMulticastAndBroadcast(t *testing.T) {
 // interested endpoints.
 func TestReuseAddrAndBroadcast(t *testing.T) {
 	const (
-		nicID             = 1
-		localPort         = 9000
-		loopbackBroadcast = tcpip.Address("\x7f\xff\xff\xff")
+		nicID     = 1
+		localPort = 9000
 	)
+	loopbackBroadcast := testutil.MustParse4("127.255.255.255")
 
 	tests := []struct {
 		name          string
diff --git a/pkg/tcpip/tests/integration/route_test.go b/pkg/tcpip/tests/integration/route_test.go
index 78244f4eb..ac3c703d4 100644
--- a/pkg/tcpip/tests/integration/route_test.go
+++ b/pkg/tcpip/tests/integration/route_test.go
@@ -30,6 +30,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/tests/utils"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -40,13 +41,13 @@ import (
 // This tests that a local route is created and packets do not leave the stack.
 func TestLocalPing(t *testing.T) {
 	const (
-		nicID        = 1
-		ipv4Loopback = tcpip.Address("\x7f\x00\x00\x01")
+		nicID = 1
 
 		// icmpDataOffset is the offset to the data in both ICMPv4 and ICMPv6 echo
 		// request/reply packets.
 		icmpDataOffset = 8
 	)
+	ipv4Loopback := testutil.MustParse4("127.0.0.1")
 
 	channelEP := func() stack.LinkEndpoint { return channel.New(1, header.IPv6MinimumMTU, "") }
 	channelEPCheck := func(t *testing.T, e stack.LinkEndpoint) {
diff --git a/pkg/tcpip/testutil/BUILD b/pkg/tcpip/testutil/BUILD
new file mode 100644
index 000000000..472545a5d
--- /dev/null
+++ b/pkg/tcpip/testutil/BUILD
@@ -0,0 +1,18 @@
+load("//tools:defs.bzl", "go_library", "go_test")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "testutil",
+    testonly = True,
+    srcs = ["testutil.go"],
+    visibility = ["//visibility:public"],
+    deps = ["//pkg/tcpip"],
+)
+
+go_test(
+    name = "testutil_test",
+    srcs = ["testutil_test.go"],
+    library = ":testutil",
+    deps = ["//pkg/tcpip"],
+)
diff --git a/pkg/tcpip/testutil/testutil.go b/pkg/tcpip/testutil/testutil.go
new file mode 100644
index 000000000..1aaed590f
--- /dev/null
+++ b/pkg/tcpip/testutil/testutil.go
@@ -0,0 +1,43 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package testutil provides helper functions for netstack unit tests.
+package testutil
+
+import (
+	"fmt"
+	"net"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+// MustParse4 parses an IPv4 string (e.g. "192.168.1.1") into a tcpip.Address.
+// Passing an IPv4-mapped IPv6 address will yield only the 4 IPv4 bytes.
+func MustParse4(addr string) tcpip.Address {
+	ip := net.ParseIP(addr).To4()
+	if ip == nil {
+		panic(fmt.Sprintf("Parse4 expects IPv4 addresses, but was passed %q", addr))
+	}
+	return tcpip.Address(ip)
+}
+
+// MustParse6 parses an IPv6 string (e.g. "fe80::1") into a tcpip.Address. Passing
+// an IPv4 address will yield an IPv4-mapped IPv6 address.
+func MustParse6(addr string) tcpip.Address {
+	ip := net.ParseIP(addr).To16()
+	if ip == nil {
+		panic(fmt.Sprintf("Parse6 was passed malformed address %q", addr))
+	}
+	return tcpip.Address(ip)
+}
diff --git a/pkg/tcpip/testutil/testutil_test.go b/pkg/tcpip/testutil/testutil_test.go
new file mode 100644
index 000000000..6aad9585d
--- /dev/null
+++ b/pkg/tcpip/testutil/testutil_test.go
@@ -0,0 +1,103 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import (
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+// Who tests the testutils?
+
+func TestMustParse4(t *testing.T) {
+	tcs := []struct {
+		str         string
+		addr        tcpip.Address
+		shouldPanic bool
+	}{
+		{
+			str:  "127.0.0.1",
+			addr: "\x7f\x00\x00\x01",
+		}, {
+			str:         "",
+			shouldPanic: true,
+		}, {
+			str:         "fe80::1",
+			shouldPanic: true,
+		}, {
+			// In an ideal world this panics too, but net.IP
+			// doesn't distinguish between IPv4 and IPv4-mapped
+			// addresses.
+			str:  "::ffff:0.0.0.1",
+			addr: "\x00\x00\x00\x01",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.str, func(t *testing.T) {
+			if tc.shouldPanic {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Errorf("panic expected, but did not occur")
+					}
+				}()
+			}
+			if got := MustParse4(tc.str); got != tc.addr {
+				t.Errorf("got MustParse4(%s) = %s, want = %s", tc.str, got, tc.addr)
+			}
+		})
+	}
+}
+
+func TestMustParse6(t *testing.T) {
+	tcs := []struct {
+		str         string
+		addr        tcpip.Address
+		shouldPanic bool
+	}{
+		{
+			// In an ideal world this panics too, but net.IP
+			// doesn't distinguish between IPv4 and IPv4-mapped
+			// addresses.
+			str:  "127.0.0.1",
+			addr: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x7f\x00\x00\x01",
+		}, {
+			str:         "",
+			shouldPanic: true,
+		}, {
+			str:  "fe80::1",
+			addr: "\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+		}, {
+			str:  "::ffff:0.0.0.1",
+			addr: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x01",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.str, func(t *testing.T) {
+			if tc.shouldPanic {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Errorf("panic expected, but did not occur")
+					}
+				}()
+			}
+			if got := MustParse6(tc.str); got != tc.addr {
+				t.Errorf("got MustParse6(%s) = %s, want = %s", tc.str, got, tc.addr)
+			}
+		})
+	}
+}
diff --git a/pkg/tcpip/transport/tcp/BUILD b/pkg/tcpip/transport/tcp/BUILD
index a69d6624d..b09a0ebbc 100644
--- a/pkg/tcpip/transport/tcp/BUILD
+++ b/pkg/tcpip/transport/tcp/BUILD
@@ -107,6 +107,7 @@ go_test(
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/seqnum",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/tcp/testing/context",
         "//pkg/test/testutil",
         "//pkg/waiter",
diff --git a/pkg/tcpip/transport/tcp/tcp_test.go b/pkg/tcpip/transport/tcp/tcp_test.go
index cda3ecbcd..1cdc41fd3 100644
--- a/pkg/tcpip/transport/tcp/tcp_test.go
+++ b/pkg/tcpip/transport/tcp/tcp_test.go
@@ -35,6 +35,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/seqnum"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	tcpiptestutil "gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp/testing/context"
 	"gvisor.dev/gvisor/pkg/test/testutil"
@@ -5529,8 +5530,8 @@ func TestListenBacklogFull(t *testing.T) {
 // TestListenNoAcceptMulticastBroadcastV4 makes sure that TCP segments with a
 // non unicast IPv4 address are not accepted.
 func TestListenNoAcceptNonUnicastV4(t *testing.T) {
-	multicastAddr := tcpip.Address("\xe0\x00\x01\x02")
-	otherMulticastAddr := tcpip.Address("\xe0\x00\x01\x03")
+	multicastAddr := tcpiptestutil.MustParse4("224.0.1.2")
+	otherMulticastAddr := tcpiptestutil.MustParse4("224.0.1.3")
 	subnet := context.StackAddrWithPrefix.Subnet()
 	subnetBroadcastAddr := subnet.Broadcast()
 
@@ -5641,8 +5642,8 @@ func TestListenNoAcceptNonUnicastV4(t *testing.T) {
 // TestListenNoAcceptMulticastBroadcastV6 makes sure that TCP segments with a
 // non unicast IPv6 address are not accepted.
 func TestListenNoAcceptNonUnicastV6(t *testing.T) {
-	multicastAddr := tcpip.Address("\xff\x0e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01")
-	otherMulticastAddr := tcpip.Address("\xff\x0e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x02")
+	multicastAddr := tcpiptestutil.MustParse6("ff0e::101")
+	otherMulticastAddr := tcpiptestutil.MustParse6("ff0e::102")
 
 	tests := []struct {
 		name    string
diff --git a/pkg/tcpip/transport/udp/BUILD b/pkg/tcpip/transport/udp/BUILD
index 153e8c950..dd5c910ae 100644
--- a/pkg/tcpip/transport/udp/BUILD
+++ b/pkg/tcpip/transport/udp/BUILD
@@ -56,6 +56,7 @@ go_test(
         "//pkg/tcpip/network/ipv4",
         "//pkg/tcpip/network/ipv6",
         "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
         "//pkg/waiter",
         "@com_github_google_go_cmp//cmp:go_default_library",
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index 77ca70a04..dc2e3f493 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -34,6 +34,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -2364,7 +2365,7 @@ func TestOutgoingSubnetBroadcast(t *testing.T) {
 	}
 	ipv4Subnet := ipv4Addr.Subnet()
 	ipv4SubnetBcast := ipv4Subnet.Broadcast()
-	ipv4Gateway := tcpip.Address("\xc0\xa8\x01\x01")
+	ipv4Gateway := testutil.MustParse4("192.168.1.1")
 	ipv4AddrPrefix31 := tcpip.AddressWithPrefix{
 		Address:   "\xc0\xa8\x01\x3a",
 		PrefixLen: 31,