Automated rollback of changelist 211103930

PiperOrigin-RevId: 211156845
Change-Id: Ie28011d7eb5f45f3a0158dbee2a68c5edf22f6e0

10 files changed, 27 insertions, 490 deletions

diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go
index dd3fe7c87..9d69f1d45 100644
--- a/pkg/tcpip/link/channel/channel.go
+++ b/pkg/tcpip/link/channel/channel.go
@@ -71,12 +71,6 @@ func (e *Endpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv *buffer.Vecto
 	e.dispatcher.DeliverNetworkPacket(e, "", protocol, &uu)
 }
 
-// InjectLinkAddr injects an inbound packet with a remote link address.
-func (e *Endpoint) InjectLinkAddr(protocol tcpip.NetworkProtocolNumber, remoteLinkAddr tcpip.LinkAddress, vv *buffer.VectorisedView) {
-	uu := vv.Clone(nil)
-	e.dispatcher.DeliverNetworkPacket(e, remoteLinkAddr, protocol, &uu)
-}
-
 // Attach saves the stack network-layer dispatcher for use later when packets
 // are injected.
 func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
diff --git a/pkg/tcpip/link/sniffer/sniffer.go b/pkg/tcpip/link/sniffer/sniffer.go
index 1e302f557..414a7edb4 100644
--- a/pkg/tcpip/link/sniffer/sniffer.go
+++ b/pkg/tcpip/link/sniffer/sniffer.go
@@ -303,37 +303,6 @@ func logPacket(prefix string, protocol tcpip.NetworkProtocolNumber, b, plb []byt
 		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
 		return
 
-	case header.ICMPv6ProtocolNumber:
-		transName = "icmp"
-		icmp := header.ICMPv6(b)
-		icmpType := "unknown"
-		switch icmp.Type() {
-		case header.ICMPv6DstUnreachable:
-			icmpType = "destination unreachable"
-		case header.ICMPv6PacketTooBig:
-			icmpType = "packet too big"
-		case header.ICMPv6TimeExceeded:
-			icmpType = "time exceeded"
-		case header.ICMPv6ParamProblem:
-			icmpType = "param problem"
-		case header.ICMPv6EchoRequest:
-			icmpType = "echo request"
-		case header.ICMPv6EchoReply:
-			icmpType = "echo reply"
-		case header.ICMPv6RouterSolicit:
-			icmpType = "router solicit"
-		case header.ICMPv6RouterAdvert:
-			icmpType = "router advert"
-		case header.ICMPv6NeighborSolicit:
-			icmpType = "neighbor solicit"
-		case header.ICMPv6NeighborAdvert:
-			icmpType = "neighbor advert"
-		case header.ICMPv6RedirectMsg:
-			icmpType = "redirect message"
-		}
-		log.Infof("%s %s %v -> %v %s len:%d id:%04x code:%d", prefix, transName, src, dst, icmpType, size, id, icmp.Code())
-		return
-
 	case header.UDPProtocolNumber:
 		transName = "udp"
 		udp := header.UDP(b)
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 512ef0d60..e6b1f5128 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -67,7 +67,7 @@ func newEndpoint(nicid tcpip.NICID, addr tcpip.Address, dispatcher stack.Transpo
 		fragmentation: fragmentation.NewFragmentation(fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout),
 	}
 	copy(e.address[:], addr)
-	e.id = stack.NetworkEndpointID{LocalAddress: tcpip.Address(e.address[:])}
+	e.id = stack.NetworkEndpointID{tcpip.Address(e.address[:])}
 
 	go e.echoReplier()
 
diff --git a/pkg/tcpip/network/ipv6/BUILD b/pkg/tcpip/network/ipv6/BUILD
index 2f19a659e..1c3eccae0 100644
--- a/pkg/tcpip/network/ipv6/BUILD
+++ b/pkg/tcpip/network/ipv6/BUILD
@@ -1,6 +1,6 @@
 package(licenses = ["notice"])  # Apache 2.0
 
-load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
+load("//tools/go_stateify:defs.bzl", "go_library")
 
 go_library(
     name = "ipv6",
@@ -19,20 +19,3 @@ go_library(
         "//pkg/tcpip/stack",
     ],
 )
-
-go_test(
-    name = "ipv6_test",
-    size = "small",
-    srcs = ["icmp_test.go"],
-    embed = [":ipv6"],
-    deps = [
-        "//pkg/tcpip",
-        "//pkg/tcpip/buffer",
-        "//pkg/tcpip/header",
-        "//pkg/tcpip/link/channel",
-        "//pkg/tcpip/link/sniffer",
-        "//pkg/tcpip/stack",
-        "//pkg/tcpip/transport/ping",
-        "//pkg/waiter",
-    ],
-)
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 6db004baa..8b8539def 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -17,7 +17,6 @@ package ipv6
 import (
 	"encoding/binary"
 
-	"gvisor.googlesource.com/gvisor/pkg/tcpip"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
@@ -87,141 +86,5 @@ func (e *endpoint) handleICMP(r *stack.Route, vv *buffer.VectorisedView) {
 		case header.ICMPv6PortUnreachable:
 			e.handleControl(stack.ControlPortUnreachable, 0, vv)
 		}
-
-	case header.ICMPv6NeighborSolicit:
-		if len(v) < header.ICMPv6NeighborSolicitMinimumSize {
-			return
-		}
-		targetAddr := tcpip.Address(v[8 : 8+16])
-		if e.linkAddrCache.CheckLocalAddress(e.nicid, ProtocolNumber, targetAddr) == 0 {
-			// We don't have a useful answer; the best we can do is ignore the request.
-			return
-		}
-		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize)
-		pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize))
-		pkt.SetType(header.ICMPv6NeighborAdvert)
-		pkt[icmpV6FlagOffset] = ndpSolicitedFlag | ndpOverrideFlag
-		copy(pkt[icmpV6OptOffset-len(targetAddr):], targetAddr)
-		pkt[icmpV6OptOffset] = ndpOptDstLinkAddr
-		pkt[icmpV6LengthOffset] = 1
-		copy(pkt[icmpV6LengthOffset+1:], r.LocalLinkAddress[:])
-		pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, nil))
-		r.WritePacket(&hdr, nil, header.ICMPv6ProtocolNumber)
-
-		e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress)
-
-	case header.ICMPv6NeighborAdvert:
-		if len(v) < header.ICMPv6NeighborAdvertSize {
-			return
-		}
-		targetAddr := tcpip.Address(v[8 : 8+16])
-		e.linkAddrCache.AddLinkAddress(e.nicid, targetAddr, r.RemoteLinkAddress)
-		if targetAddr != r.RemoteAddress {
-			e.linkAddrCache.AddLinkAddress(e.nicid, r.RemoteAddress, r.RemoteLinkAddress)
-		}
-
-	case header.ICMPv6EchoRequest:
-		if len(v) < header.ICMPv6EchoMinimumSize {
-			return
-		}
-		vv.TrimFront(header.ICMPv6EchoMinimumSize)
-		data := vv.ToView()
-		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6EchoMinimumSize)
-		pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize))
-		copy(pkt, h)
-		pkt.SetType(header.ICMPv6EchoReply)
-		pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, data))
-		r.WritePacket(&hdr, data, header.ICMPv6ProtocolNumber)
-
-	case header.ICMPv6EchoReply:
-		if len(v) < header.ICMPv6EchoMinimumSize {
-			return
-		}
-		e.dispatcher.DeliverTransportPacket(r, header.ICMPv6ProtocolNumber, vv)
-
 	}
 }
-
-const (
-	ndpSolicitedFlag = 1 << 6
-	ndpOverrideFlag  = 1 << 5
-
-	ndpOptSrcLinkAddr = 1
-	ndpOptDstLinkAddr = 2
-
-	icmpV6FlagOffset   = 4
-	icmpV6OptOffset    = 24
-	icmpV6LengthOffset = 25
-
-	icmpV6HopLimit = 255
-)
-
-// solicitedNodeAddr computes the solicited-node multicast address.
-// This is used for NDP. Described in RFC 4291.
-func solicitedNodeAddr(addr tcpip.Address) tcpip.Address {
-	const solicitedNodeMulticastPrefix = "\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xff"
-	return solicitedNodeMulticastPrefix + addr[len(addr)-3:]
-}
-
-var broadcastMAC = tcpip.LinkAddress([]byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff})
-
-var _ stack.LinkAddressResolver = (*protocol)(nil)
-
-// LinkAddressProtocol implements stack.LinkAddressResolver.
-func (*protocol) LinkAddressProtocol() tcpip.NetworkProtocolNumber {
-	return header.IPv6ProtocolNumber
-}
-
-// LinkAddressRequest implements stack.LinkAddressResolver.
-func (*protocol) LinkAddressRequest(addr, localAddr tcpip.Address, linkEP stack.LinkEndpoint) *tcpip.Error {
-	snaddr := solicitedNodeAddr(addr)
-	r := &stack.Route{
-		LocalAddress:      localAddr,
-		RemoteAddress:     snaddr,
-		RemoteLinkAddress: broadcastMAC,
-	}
-	hdr := buffer.NewPrependable(int(linkEP.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6NeighborAdvertSize)
-	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborAdvertSize))
-	pkt.SetType(header.ICMPv6NeighborSolicit)
-	copy(pkt[icmpV6OptOffset-len(addr):], addr)
-	pkt[icmpV6OptOffset] = ndpOptSrcLinkAddr
-	pkt[icmpV6LengthOffset] = 1
-	copy(pkt[icmpV6LengthOffset+1:], linkEP.LinkAddress())
-	pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, nil))
-
-	length := uint16(hdr.UsedLength())
-	ip := header.IPv6(hdr.Prepend(header.IPv6MinimumSize))
-	ip.Encode(&header.IPv6Fields{
-		PayloadLength: length,
-		NextHeader:    uint8(header.ICMPv6ProtocolNumber),
-		HopLimit:      icmpV6HopLimit,
-		SrcAddr:       r.LocalAddress,
-		DstAddr:       r.RemoteAddress,
-	})
-
-	return linkEP.WritePacket(r, &hdr, nil, ProtocolNumber)
-}
-
-// ResolveStaticAddress implements stack.LinkAddressResolver.
-func (*protocol) ResolveStaticAddress(addr tcpip.Address) (tcpip.LinkAddress, bool) {
-	return "", false
-}
-
-func icmpChecksum(h header.ICMPv6, src, dst tcpip.Address, data []byte) uint16 {
-	// Calculate the IPv6 pseudo-header upper-layer checksum.
-	xsum := header.Checksum([]byte(src), 0)
-	xsum = header.Checksum([]byte(dst), xsum)
-	var upperLayerLength [4]byte
-	binary.BigEndian.PutUint32(upperLayerLength[:], uint32(len(h)+len(data)))
-	xsum = header.Checksum(upperLayerLength[:], xsum)
-	xsum = header.Checksum([]byte{0, 0, 0, uint8(header.ICMPv6ProtocolNumber)}, xsum)
-	xsum = header.Checksum(data, xsum)
-
-	// h[2:4] is the checksum itself, set it aside to avoid checksumming the checksum.
-	h2, h3 := h[2], h[3]
-	h[2], h[3] = 0, 0
-	xsum = ^header.Checksum(h, xsum)
-	h[2], h[3] = h2, h3
-
-	return xsum
-}
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
deleted file mode 100644
index 582bbb40e..000000000
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ /dev/null
@@ -1,236 +0,0 @@
-// Copyright 2018 Google Inc.
-//
-// 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 ipv6
-
-import (
-	"context"
-	"runtime"
-	"strings"
-	"testing"
-	"time"
-
-	"gvisor.googlesource.com/gvisor/pkg/tcpip"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/link/channel"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/link/sniffer"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
-	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/ping"
-	"gvisor.googlesource.com/gvisor/pkg/waiter"
-)
-
-const (
-	linkAddr0 = tcpip.LinkAddress("\x01\x02\x03\x04\x05\x06")
-	linkAddr1 = tcpip.LinkAddress("\x0a\x0b\x0c\x0d\x0e\x0f")
-)
-
-// linkLocalAddr computes the default IPv6 link-local address from
-// a link-layer (MAC) address.
-func linkLocalAddr(linkAddr tcpip.LinkAddress) tcpip.Address {
-	// Convert a 48-bit MAC to an EUI-64 and then prepend the
-	// link-local header, FE80::.
-	//
-	// The conversion is very nearly:
-	//	aa:bb:cc:dd:ee:ff => FE80::Aabb:ccFF:FEdd:eeff
-	// Note the capital A. The conversion aa->Aa involves a bit flip.
-	lladdrb := [16]byte{
-		0:  0xFE,
-		1:  0x80,
-		8:  linkAddr[0] ^ 2,
-		9:  linkAddr[1],
-		10: linkAddr[2],
-		11: 0xFF,
-		12: 0xFE,
-		13: linkAddr[3],
-		14: linkAddr[4],
-		15: linkAddr[5],
-	}
-	return tcpip.Address(lladdrb[:])
-}
-
-var (
-	lladdr0 = linkLocalAddr(linkAddr0)
-	lladdr1 = linkLocalAddr(linkAddr1)
-)
-
-type testContext struct {
-	t  *testing.T
-	s0 *stack.Stack
-	s1 *stack.Stack
-
-	linkEP0 *channel.Endpoint
-	linkEP1 *channel.Endpoint
-
-	icmpCh chan header.ICMPv6Type
-}
-
-type endpointWithResolutionCapability struct {
-	stack.LinkEndpoint
-}
-
-func (e endpointWithResolutionCapability) Capabilities() stack.LinkEndpointCapabilities {
-	return e.LinkEndpoint.Capabilities() | stack.CapabilityResolutionRequired
-}
-
-func newTestContext(t *testing.T) *testContext {
-	c := &testContext{
-		t:      t,
-		s0:     stack.New([]string{ProtocolName}, []string{ping.ProtocolName6}, stack.Options{}),
-		s1:     stack.New([]string{ProtocolName}, []string{ping.ProtocolName6}, stack.Options{}),
-		icmpCh: make(chan header.ICMPv6Type, 10),
-	}
-
-	const defaultMTU = 65536
-	_, linkEP0 := channel.New(256, defaultMTU, linkAddr0)
-	c.linkEP0 = linkEP0
-	wrappedEP0 := endpointWithResolutionCapability{LinkEndpoint: linkEP0}
-	id0 := stack.RegisterLinkEndpoint(wrappedEP0)
-	if testing.Verbose() {
-		id0 = sniffer.New(id0)
-	}
-	if err := c.s0.CreateNIC(1, id0); err != nil {
-		t.Fatalf("CreateNIC s0: %v", err)
-	}
-	if err := c.s0.AddAddress(1, ProtocolNumber, lladdr0); err != nil {
-		t.Fatalf("AddAddress lladdr0: %v", err)
-	}
-	if err := c.s0.AddAddress(1, ProtocolNumber, solicitedNodeAddr(lladdr0)); err != nil {
-		t.Fatalf("AddAddress sn lladdr0: %v", err)
-	}
-
-	_, linkEP1 := channel.New(256, defaultMTU, linkAddr1)
-	c.linkEP1 = linkEP1
-	wrappedEP1 := endpointWithResolutionCapability{LinkEndpoint: linkEP1}
-	id1 := stack.RegisterLinkEndpoint(wrappedEP1)
-	if err := c.s1.CreateNIC(1, id1); err != nil {
-		t.Fatalf("CreateNIC failed: %v", err)
-	}
-	if err := c.s1.AddAddress(1, ProtocolNumber, lladdr1); err != nil {
-		t.Fatalf("AddAddress lladdr1: %v", err)
-	}
-	if err := c.s1.AddAddress(1, ProtocolNumber, solicitedNodeAddr(lladdr1)); err != nil {
-		t.Fatalf("AddAddress sn lladdr1: %v", err)
-	}
-
-	c.s0.SetRouteTable(
-		[]tcpip.Route{{
-			Destination: lladdr1,
-			Mask:        tcpip.Address(strings.Repeat("\xff", 16)),
-			NIC:         1,
-		}},
-	)
-	c.s1.SetRouteTable(
-		[]tcpip.Route{{
-			Destination: lladdr0,
-			Mask:        tcpip.Address(strings.Repeat("\xff", 16)),
-			NIC:         1,
-		}},
-	)
-
-	go c.routePackets(linkEP0.C, linkEP1)
-	go c.routePackets(linkEP1.C, linkEP0)
-
-	return c
-}
-
-func (c *testContext) countPacket(pkt channel.PacketInfo) {
-	if pkt.Proto != ProtocolNumber {
-		return
-	}
-	ipv6 := header.IPv6(pkt.Header)
-	transProto := tcpip.TransportProtocolNumber(ipv6.NextHeader())
-	if transProto != header.ICMPv6ProtocolNumber {
-		return
-	}
-	b := pkt.Header[header.IPv6MinimumSize:]
-	icmp := header.ICMPv6(b)
-	c.icmpCh <- icmp.Type()
-}
-
-func (c *testContext) routePackets(ch <-chan channel.PacketInfo, ep *channel.Endpoint) {
-	for pkt := range ch {
-		c.countPacket(pkt)
-		views := []buffer.View{pkt.Header, pkt.Payload}
-		size := len(pkt.Header) + len(pkt.Payload)
-		vv := buffer.NewVectorisedView(size, views)
-		ep.InjectLinkAddr(pkt.Proto, ep.LinkAddress(), &vv)
-	}
-}
-
-func (c *testContext) cleanup() {
-	close(c.linkEP0.C)
-	close(c.linkEP1.C)
-}
-
-func TestLinkResolution(t *testing.T) {
-	c := newTestContext(t)
-	defer c.cleanup()
-	r, err := c.s0.FindRoute(1, lladdr0, lladdr1, ProtocolNumber)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer r.Release()
-
-	hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6EchoMinimumSize)
-	pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize))
-	pkt.SetType(header.ICMPv6EchoRequest)
-	pkt.SetChecksum(icmpChecksum(pkt, r.LocalAddress, r.RemoteAddress, nil))
-	payload := tcpip.SlicePayload(hdr.UsedBytes())
-
-	// We can't send our payload directly over the route because that
-	// doesn't provoke NDP discovery.
-	var wq waiter.Queue
-	ep, err := c.s0.NewEndpoint(header.ICMPv6ProtocolNumber, ProtocolNumber, &wq)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// This actually takes about 10 milliseconds, so no need to wait for
-	// a multi-minute go test timeout if something is broken.
-	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
-	defer cancel()
-
-	for {
-		if ctx.Err() != nil {
-			break
-		}
-		if _, err := ep.Write(payload, tcpip.WriteOptions{To: &tcpip.FullAddress{NIC: 1, Addr: lladdr1}}); err == tcpip.ErrNoLinkAddress {
-			// There's something asynchronous going on; yield to let it do its thing.
-			runtime.Gosched()
-		} else if err == nil {
-			break
-		} else {
-			t.Fatal(err)
-		}
-	}
-
-	stats := make(map[header.ICMPv6Type]int)
-	for {
-		select {
-		case <-ctx.Done():
-			t.Errorf("timeout waiting for ICMP, got: %#+v", stats)
-			return
-		case typ := <-c.icmpCh:
-			stats[typ]++
-
-			if stats[header.ICMPv6NeighborSolicit] > 0 &&
-				stats[header.ICMPv6NeighborAdvert] > 0 &&
-				stats[header.ICMPv6EchoRequest] > 0 &&
-				stats[header.ICMPv6EchoReply] > 0 {
-				return
-			}
-		}
-	}
-}
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 51d34b7ec..f48d120c5 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -42,12 +42,18 @@ const (
 type address [header.IPv6AddressSize]byte
 
 type endpoint struct {
-	nicid         tcpip.NICID
-	id            stack.NetworkEndpointID
-	address       address
-	linkEP        stack.LinkEndpoint
-	linkAddrCache stack.LinkAddressCache
-	dispatcher    stack.TransportDispatcher
+	nicid      tcpip.NICID
+	id         stack.NetworkEndpointID
+	address    address
+	linkEP     stack.LinkEndpoint
+	dispatcher stack.TransportDispatcher
+}
+
+func newEndpoint(nicid tcpip.NICID, addr tcpip.Address, dispatcher stack.TransportDispatcher, linkEP stack.LinkEndpoint) *endpoint {
+	e := &endpoint{nicid: nicid, linkEP: linkEP, dispatcher: dispatcher}
+	copy(e.address[:], addr)
+	e.id = stack.NetworkEndpointID{tcpip.Address(e.address[:])}
+	return e
 }
 
 // MTU implements stack.NetworkEndpoint.MTU. It returns the link-layer MTU minus
@@ -87,7 +93,7 @@ func (e *endpoint) WritePacket(r *stack.Route, hdr *buffer.Prependable, payload
 	ip.Encode(&header.IPv6Fields{
 		PayloadLength: length,
 		NextHeader:    uint8(protocol),
-		HopLimit:      icmpV6HopLimit,
+		HopLimit:      65,
 		SrcAddr:       tcpip.Address(e.address[:]),
 		DstAddr:       r.RemoteAddress,
 	})
@@ -148,15 +154,7 @@ func (*protocol) ParseAddresses(v buffer.View) (src, dst tcpip.Address) {
 
 // NewEndpoint creates a new ipv6 endpoint.
 func (p *protocol) NewEndpoint(nicid tcpip.NICID, addr tcpip.Address, linkAddrCache stack.LinkAddressCache, dispatcher stack.TransportDispatcher, linkEP stack.LinkEndpoint) (stack.NetworkEndpoint, *tcpip.Error) {
-	e := &endpoint{
-		nicid:         nicid,
-		linkEP:        linkEP,
-		linkAddrCache: linkAddrCache,
-		dispatcher:    dispatcher,
-	}
-	copy(e.address[:], addr)
-	e.id = stack.NetworkEndpointID{LocalAddress: tcpip.Address(e.address[:])}
-	return e, nil
+	return newEndpoint(nicid, addr, dispatcher, linkEP), nil
 }
 
 // SetOption implements NetworkProtocol.SetOption.
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index 77134c42a..c158e2005 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -165,7 +165,7 @@ func (n *NIC) addAddressLocked(protocol tcpip.NetworkProtocolNumber, addr tcpip.
 
 	// Set up cache if link address resolution exists for this protocol.
 	if n.linkEP.Capabilities()&CapabilityResolutionRequired != 0 {
-		if _, ok := n.stack.linkAddrResolvers[protocol]; ok {
+		if linkRes := n.stack.linkAddrResolvers[protocol]; linkRes != nil {
 			ref.linkCache = n.stack
 		}
 	}
diff --git a/pkg/tcpip/transport/ping/endpoint.go b/pkg/tcpip/transport/ping/endpoint.go
index 7e10c0aae..f097ac057 100644
--- a/pkg/tcpip/transport/ping/endpoint.go
+++ b/pkg/tcpip/transport/ping/endpoint.go
@@ -56,7 +56,6 @@ type endpoint struct {
 	// change throughout the lifetime of the endpoint.
 	stack       *stack.Stack `state:"manual"`
 	netProto    tcpip.NetworkProtocolNumber
-	transProto  tcpip.TransportProtocolNumber
 	waiterQueue *waiter.Queue
 
 	// The following fields are used to manage the receive queue, and are
@@ -82,11 +81,10 @@ type endpoint struct {
 	route         stack.Route `state:"manual"`
 }
 
-func newEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, waiterQueue *waiter.Queue) *endpoint {
+func newEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) *endpoint {
 	return &endpoint{
 		stack:         stack,
 		netProto:      netProto,
-		transProto:    transProto,
 		waiterQueue:   waiterQueue,
 		rcvBufSizeMax: 32 * 1024,
 		sndBufSize:    32 * 1024,
@@ -100,7 +98,7 @@ func (e *endpoint) Close() {
 	e.shutdownFlags = tcpip.ShutdownRead | tcpip.ShutdownWrite
 	switch e.state {
 	case stateBound, stateConnected:
-		e.stack.UnregisterTransportEndpoint(e.regNICID, []tcpip.NetworkProtocolNumber{e.netProto}, e.transProto, e.id)
+		e.stack.UnregisterTransportEndpoint(e.regNICID, []tcpip.NetworkProtocolNumber{e.netProto}, ProtocolNumber4, e.id)
 	}
 
 	// Close the receive list and drain it.
@@ -299,7 +297,7 @@ func (e *endpoint) Write(p tcpip.Payload, opts tcpip.WriteOptions) (uintptr, *tc
 		err = sendPing4(route, e.id.LocalPort, v)
 
 	case header.IPv6ProtocolNumber:
-		err = sendPing6(route, e.id.LocalPort, v)
+		// TODO: Support IPv6.
 	}
 
 	return uintptr(len(v)), err
@@ -387,30 +385,6 @@ func sendPing4(r *stack.Route, ident uint16, data buffer.View) *tcpip.Error {
 	return r.WritePacket(&hdr, data, header.ICMPv4ProtocolNumber)
 }
 
-func sendPing6(r *stack.Route, ident uint16, data buffer.View) *tcpip.Error {
-	if len(data) < header.ICMPv6EchoMinimumSize {
-		return tcpip.ErrInvalidEndpointState
-	}
-
-	// Set the ident. Sequence number is provided by the user.
-	binary.BigEndian.PutUint16(data[header.ICMPv6MinimumSize:], ident)
-
-	hdr := buffer.NewPrependable(header.ICMPv6EchoMinimumSize + int(r.MaxHeaderLength()))
-
-	icmpv6 := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize))
-	copy(icmpv6, data)
-	data = data[header.ICMPv6EchoMinimumSize:]
-
-	if icmpv6.Type() != header.ICMPv6EchoRequest || icmpv6.Code() != 0 {
-		return tcpip.ErrInvalidEndpointState
-	}
-
-	icmpv6.SetChecksum(0)
-	icmpv6.SetChecksum(^header.Checksum(icmpv6, header.Checksum(data, 0)))
-
-	return r.WritePacket(&hdr, data, header.ICMPv6ProtocolNumber)
-}
-
 func (e *endpoint) checkV4Mapped(addr *tcpip.FullAddress, allowMismatch bool) (tcpip.NetworkProtocolNumber, *tcpip.Error) {
 	netProto := e.netProto
 	if header.IsV4MappedAddress(addr.Addr) {
@@ -534,14 +508,14 @@ func (e *endpoint) registerWithStack(nicid tcpip.NICID, netProtos []tcpip.Networ
 	if id.LocalPort != 0 {
 		// The endpoint already has a local port, just attempt to
 		// register it.
-		err := e.stack.RegisterTransportEndpoint(nicid, netProtos, e.transProto, id, e)
+		err := e.stack.RegisterTransportEndpoint(nicid, netProtos, ProtocolNumber4, id, e)
 		return id, err
 	}
 
 	// We need to find a port for the endpoint.
 	_, err := e.stack.PickEphemeralPort(func(p uint16) (bool, *tcpip.Error) {
 		id.LocalPort = p
-		err := e.stack.RegisterTransportEndpoint(nicid, netProtos, e.transProto, id, e)
+		err := e.stack.RegisterTransportEndpoint(nicid, netProtos, ProtocolNumber4, id, e)
 		switch err {
 		case nil:
 			return true, nil
@@ -590,7 +564,7 @@ func (e *endpoint) bindLocked(addr tcpip.FullAddress, commit func() *tcpip.Error
 	if commit != nil {
 		if err := commit(); err != nil {
 			// Unregister, the commit failed.
-			e.stack.UnregisterTransportEndpoint(addr.NIC, netProtos, e.transProto, id)
+			e.stack.UnregisterTransportEndpoint(addr.NIC, netProtos, ProtocolNumber4, id)
 			return err
 		}
 	}
diff --git a/pkg/tcpip/transport/ping/protocol.go b/pkg/tcpip/transport/ping/protocol.go
index b885f3627..8a8192064 100644
--- a/pkg/tcpip/transport/ping/protocol.go
+++ b/pkg/tcpip/transport/ping/protocol.go
@@ -71,7 +71,7 @@ func (p *protocol) NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtoco
 	if netProto != p.netProto() {
 		return nil, tcpip.ErrUnknownProtocol
 	}
-	return newEndpoint(stack, netProto, p.number, waiterQueue), nil
+	return newEndpoint(stack, netProto, waiterQueue), nil
 }
 
 // MinimumPacketSize returns the minimum valid ping packet size.
@@ -87,14 +87,8 @@ func (p *protocol) MinimumPacketSize() int {
 
 // ParsePorts returns the source and destination ports stored in the given ping
 // packet.
-func (p *protocol) ParsePorts(v buffer.View) (src, dst uint16, err *tcpip.Error) {
-	switch p.number {
-	case ProtocolNumber4:
-		return 0, binary.BigEndian.Uint16(v[header.ICMPv4MinimumSize:]), nil
-	case ProtocolNumber6:
-		return 0, binary.BigEndian.Uint16(v[header.ICMPv6MinimumSize:]), nil
-	}
-	panic(fmt.Sprint("unknown protocol number: ", p.number))
+func (*protocol) ParsePorts(v buffer.View) (src, dst uint16, err *tcpip.Error) {
+	return 0, binary.BigEndian.Uint16(v[header.ICMPv4MinimumSize:]), nil
 }
 
 // HandleUnknownDestinationPacket handles packets targeted at this protocol but
@@ -118,7 +112,5 @@ func init() {
 		return &protocol{ProtocolNumber4}
 	})
 
-	stack.RegisterTransportProtocolFactory(ProtocolName6, func() stack.TransportProtocol {
-		return &protocol{ProtocolNumber6}
-	})
+	// TODO: Support IPv6.
 }