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Default to NUD/neighborCache instead of linkAddrCache 

This change flips gvisor to use Neighbor unreachability detection by
default to populate the neighbor table as defined by RFC 4861 section 7.
Although RFC 4861 is targeted at IPv6, the same algorithm is used for
link resolution on IPv4 networks using ARP.

Integrators may still use the legacy link address cache by setting
stack.Options.UseLinkAddrCache to true; stack.Options.UseNeighborCache
is now unused and will be removed.

A later change will remove linkAddrCache and associated code.

Updates #4658.

PiperOrigin-RevId: 354850531
This commit is contained in:
Ghanan Gowripalan 2021-01-31 18:46:52 -08:00 committed by gVisor bot
parent c5e3c1c7bd
commit d930def27a
2 changed files with 13 additions and 6 deletions
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1
pkg/tcpip/network/ipv6/ndp_test.go
View File

@ -759,6 +759,7 @@ func TestNeighborAdvertisementWithTargetLinkLayerOption(t *testing.T) {
t.Run(test.name, func(t *testing.T) {
s := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
UseLinkAddrCache: true,
})
e := channel.New(0, 1280, linkAddr0)
e.LinkEPCapabilities |= stack.CapabilityResolutionRequired

18
pkg/tcpip/stack/stack.go
View File

@ -436,6 +436,8 @@ type Stack struct {
// useNeighborCache indicates whether ARP and NDP packets should be handled
// by the NIC's neighborCache instead of linkAddrCache.
//
// TODO(gvisor.dev/issue/4658): Remove this field.
useNeighborCache bool
// nudDisp is the NUD event dispatcher that is used to send the netstack
@ -502,13 +504,17 @@ type Options struct {
// NUDConfigs is the default NUD configurations used by interfaces.
NUDConfigs NUDConfigurations
// UseNeighborCache indicates whether ARP and NDP packets should be handled
// by the Neighbor Unreachability Detection (NUD) state machine. This flag
// also enables the APIs for inspecting and modifying the neighbor table via
// NUDDispatcher and the following Stack methods: Neighbors, RemoveNeighbor,
// and ClearNeighbors.
// UseNeighborCache is unused.
//
// TODO(gvisor.dev/issue/4658): Remove this field.
UseNeighborCache bool
// UseLinkAddrCache indicates that the legacy link address cache should be
// used for link resolution.
//
// TODO(gvisor.dev/issue/4658): Remove this field.
UseLinkAddrCache bool
// NUDDisp is the NUD event dispatcher that an integrator can provide to
// receive NUD related events.
NUDDisp NUDDispatcher
@ -648,7 +654,7 @@ func New(opts Options) *Stack {
icmpRateLimiter: NewICMPRateLimiter(),
seed: generateRandUint32(),
nudConfigs: opts.NUDConfigs,
useNeighborCache: opts.UseNeighborCache,
useNeighborCache: !opts.UseLinkAddrCache,
uniqueIDGenerator: opts.UniqueID,
nudDisp: opts.NUDDisp,
randomGenerator: mathrand.New(randSrc),