From 6768e6c59ec252854a1633e184b69dc5723ac3f3 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Thu, 8 Oct 2020 16:14:01 -0700
Subject: Do not resolve routes immediately

When a response needs to be sent to an incoming packet, the stack should
consult its neighbour table to determine the remote address's link
address.

When an entry does not exist in the stack's neighbor table, the stack
should queue the packet while link resolution completes. See comments.

PiperOrigin-RevId: 336185457
---
 pkg/tcpip/stack/stack_test.go | 62 +++++--------------------------------------
 1 file changed, 6 insertions(+), 56 deletions(-)

(limited to 'pkg/tcpip/stack/stack_test.go')

diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index aa20f750b..38994cca1 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -21,7 +21,6 @@ import (
 	"bytes"
 	"fmt"
 	"math"
-	"net"
 	"sort"
 	"testing"
 	"time"
@@ -35,7 +34,6 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/link/loopback"
-	"gvisor.dev/gvisor/pkg/tcpip/network/arp"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
@@ -77,10 +75,9 @@ type fakeNetworkEndpoint struct {
 		enabled bool
 	}
 
-	nicID      tcpip.NICID
+	nic        stack.NetworkInterface
 	proto      *fakeNetworkProtocol
 	dispatcher stack.TransportDispatcher
-	ep         stack.LinkEndpoint
 }
 
 func (f *fakeNetworkEndpoint) Enable() *tcpip.Error {
@@ -103,7 +100,7 @@ func (f *fakeNetworkEndpoint) Disable() {
 }
 
 func (f *fakeNetworkEndpoint) MTU() uint32 {
-	return f.ep.MTU() - uint32(f.MaxHeaderLength())
+	return f.nic.MTU() - uint32(f.MaxHeaderLength())
 }
 
 func (*fakeNetworkEndpoint) DefaultTTL() uint8 {
@@ -135,7 +132,7 @@ func (f *fakeNetworkEndpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuff
 }
 
 func (f *fakeNetworkEndpoint) MaxHeaderLength() uint16 {
-	return f.ep.MaxHeaderLength() + fakeNetHeaderLen
+	return f.nic.MaxHeaderLength() + fakeNetHeaderLen
 }
 
 func (f *fakeNetworkEndpoint) PseudoHeaderChecksum(protocol tcpip.TransportProtocolNumber, dstAddr tcpip.Address) uint16 {
@@ -164,7 +161,7 @@ func (f *fakeNetworkEndpoint) WritePacket(r *stack.Route, gso *stack.GSO, params
 		return nil
 	}
 
-	return f.ep.WritePacket(r, gso, fakeNetNumber, pkt)
+	return f.nic.WritePacket(r, gso, fakeNetNumber, pkt)
 }
 
 // WritePackets implements stack.LinkEndpoint.WritePackets.
@@ -216,10 +213,9 @@ func (*fakeNetworkProtocol) ParseAddresses(v buffer.View) (src, dst tcpip.Addres
 
 func (f *fakeNetworkProtocol) NewEndpoint(nic stack.NetworkInterface, _ stack.LinkAddressCache, _ stack.NUDHandler, dispatcher stack.TransportDispatcher) stack.NetworkEndpoint {
 	e := &fakeNetworkEndpoint{
-		nicID:      nic.ID(),
+		nic:        nic,
 		proto:      f,
 		dispatcher: dispatcher,
-		ep:         nic.LinkEndpoint(),
 	}
 	e.AddressableEndpointState.Init(e)
 	return e
@@ -2106,7 +2102,7 @@ func TestNICStats(t *testing.T) {
 		t.Errorf("got Tx.Packets.Value() = %d, ep1.Drain() = %d", got, want)
 	}
 
-	if got, want := s.NICInfo()[1].Stats.Tx.Bytes.Value(), uint64(len(payload)); got != want {
+	if got, want := s.NICInfo()[1].Stats.Tx.Bytes.Value(), uint64(len(payload)+fakeNetHeaderLen); got != want {
 		t.Errorf("got Tx.Bytes.Value() = %d, want = %d", got, want)
 	}
 }
@@ -3502,52 +3498,6 @@ func TestOutgoingSubnetBroadcast(t *testing.T) {
 	}
 }
 
-func TestResolveWith(t *testing.T) {
-	const (
-		unspecifiedNICID = 0
-		nicID            = 1
-	)
-
-	s := stack.New(stack.Options{
-		NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol, arp.NewProtocol},
-	})
-	ep := channel.New(0, defaultMTU, "")
-	ep.LinkEPCapabilities |= stack.CapabilityResolutionRequired
-	if err := s.CreateNIC(nicID, ep); err != nil {
-		t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
-	}
-	addr := tcpip.ProtocolAddress{
-		Protocol: header.IPv4ProtocolNumber,
-		AddressWithPrefix: tcpip.AddressWithPrefix{
-			Address:   tcpip.Address(net.ParseIP("192.168.1.58").To4()),
-			PrefixLen: 24,
-		},
-	}
-	if err := s.AddProtocolAddress(nicID, addr); err != nil {
-		t.Fatalf("AddProtocolAddress(%d, %+v): %s", nicID, addr, err)
-	}
-
-	s.SetRouteTable([]tcpip.Route{{Destination: header.IPv4EmptySubnet, NIC: nicID}})
-
-	remoteAddr := tcpip.Address(net.ParseIP("192.168.1.59").To4())
-	r, err := s.FindRoute(unspecifiedNICID, "" /* localAddr */, remoteAddr, header.IPv4ProtocolNumber, false /* multicastLoop */)
-	if err != nil {
-		t.Fatalf("FindRoute(%d, '', %s, %d): %s", unspecifiedNICID, remoteAddr, header.IPv4ProtocolNumber, err)
-	}
-	defer r.Release()
-
-	// Should initially require resolution.
-	if !r.IsResolutionRequired() {
-		t.Fatal("got r.IsResolutionRequired() = false, want = true")
-	}
-
-	// Manually resolving the route should no longer require resolution.
-	r.ResolveWith("\x01")
-	if r.IsResolutionRequired() {
-		t.Fatal("got r.IsResolutionRequired() = true, want = false")
-	}
-}
-
 // TestRouteReleaseAfterAddrRemoval tests that releasing a Route after its
 // associated address is removed should not cause a panic.
 func TestRouteReleaseAfterAddrRemoval(t *testing.T) {
-- 
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