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passive MAC learning and ARP cache revamp (#96)

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* begin working on arp cache

* fix little things

* rework arp cache priority

* fix test

* keep working on ARP

* push changes before thinking about ip prefix issue

* add passive peer MAC setting

* patch egress mac with correct ethernet CRCs

* consolidate subnet learning in subnetTable type

* add tests and fix subnet table bug
This commit is contained in:
Pat Whittingslow
2026-04-24 23:34:53 -03:00
committed by GitHub
parent 67c42aa136
commit aa77403a2b
10 changed files with 619 additions and 284 deletions
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x/xnet/stack-async.go
+31 -16
View File
@@ -39,7 +39,7 @@ type StackAsync struct {
dhcpUDP internet.StackUDPPort
dhcp dhcpv4.Client
dhcpResults DHCPResults
subnet netip.Prefix // Local subnet for ARP resolution.
arpt subnetTable
dnsUDP internet.StackUDPPort
dns dns.Client
@@ -83,6 +83,9 @@ type StackConfig struct {
// ICMPQueueLimit sets maximum number of input/output packets queued for processing.
// If set to zero ICMP cannot be enabled on the stack.
ICMPQueueLimit int
// PassivePeers limits how many subnet peers the stack passively learns MAC addresses for.
// Passively learned entries skip ARP round-trips on the first DialTCP/DialUDP to that peer.
PassivePeers int
}
func (s *StackAsync) Hostname() string {
@@ -94,7 +97,11 @@ func (s *StackAsync) IngressEthernet(ethernetFrame []byte) error {
s.mu.Lock()
defer s.mu.Unlock()
s.totalrecv += uint64(len(ethernetFrame))
return s.link.Demux(ethernetFrame, 0)
err := s.link.Demux(ethernetFrame, 0)
if err == nil {
s.arpt.learnFromIngressEthernet(ethernetFrame)
}
return err
}
// EgressEthernet writes the next ethernet frame to send into dstEthernetFrame from the stack.
@@ -137,7 +144,7 @@ func (s *StackAsync) MTU() int {
}
func (s *StackAsync) Reset(cfg StackConfig) error {
if cfg.RandSeed == 0 || cfg.Hostname == "" {
if cfg.RandSeed == 0 || cfg.Hostname == "" || cfg.PassivePeers > 255 {
return lneto.ErrInvalidConfig
}
mac := cfg.HardwareAddress
@@ -165,12 +172,18 @@ func (s *StackAsync) Reset(cfg StackConfig) error {
return err
}
s.link.SetAcceptMulticast(cfg.AcceptMulticast)
if cfg.PassivePeers == 0 {
s.link.OnEncapsulate(nil)
} else {
s.link.OnEncapsulate(s.arpt.patchEgressMAC)
}
const ipNodes = 3 // 3 IP protocols possible: UDP, TCP, ICMP.
err = s.ip.Reset(addr, ipNodes)
if err != nil {
return err
}
s.ip.SetAcceptMulticast(cfg.AcceptMulticast)
s.arpt.passivePeers = uint8(cfg.PassivePeers)
err = s.resetARP()
if err != nil {
return err
@@ -241,14 +254,16 @@ func (s *StackAsync) resetARP() error {
err := s.arp.Reset(arp.HandlerConfig{
HardwareAddr: mac[:],
ProtocolAddr: addr.AsSlice(),
MaxQueries: 3,
MaxPending: 3,
MaxQueries: 5,
MaxPending: 5,
HardwareType: 1,
ProtocolType: proto,
})
if err != nil {
return err
}
s.arpt.reset(10, s.arpt.passivePeers)
s.arp.SetOnResolveCallback(s.arpt.onResolve)
err = s.link.Register(&s.arp)
if err != nil {
return err
@@ -308,7 +323,7 @@ func (s *StackAsync) Addr() netip.Addr {
func (s *StackAsync) SetSubnet(subnetMask netip.Prefix) {
s.mu.Lock()
defer s.mu.Unlock()
s.subnet = subnetMask
s.arpt.subnet = subnetMask
}
func (s *StackAsync) SetHardwareAddress(hw [6]byte) error {
@@ -358,10 +373,10 @@ func (s *StackAsync) DialUDP(conn *udp.Conn, localPort uint16, addrp netip.AddrP
s.mu.Lock()
defer s.mu.Unlock()
var mac []byte
if s.subnet.Contains(addrp.Addr()) {
if s.arpt.subnet.Contains(addrp.Addr()) {
mac = make([]byte, 6)
ip := addrp.Addr().As4()
hw, err := s.arp.QueryResult(ip[:])
hw, err := s.arp.CacheLookup(ip[:])
if err == nil {
// MAC already contained in results.
copy(mac, hw)
@@ -369,7 +384,7 @@ func (s *StackAsync) DialUDP(conn *udp.Conn, localPort uint16, addrp netip.AddrP
// StartQuery starts an ARP query for addresses in this network.
// On finishing query MAC is set and thus the StackPort will allow encapsulating
// data on that connection.
err = s.arp.StartQuery(mac, ip[:])
err = s.arpt.startQuery(mac, ip[:], &s.arp)
if err != nil {
return err
}
@@ -387,9 +402,9 @@ func (s *StackAsync) DialTCP(conn *tcp.Conn, localPort uint16, addrp netip.AddrP
s.mu.Lock()
defer s.mu.Unlock()
var mac []byte
if s.subnet.Contains(addrp.Addr()) {
if s.arpt.subnet.Contains(addrp.Addr()) {
ip := addrp.Addr().As4()
hw, err := s.arp.QueryResult(ip[:])
hw, err := s.arp.CacheLookup(ip[:])
mac = make([]byte, 6)
if err == nil {
// Query exists, use pre-existing result.
@@ -398,7 +413,7 @@ func (s *StackAsync) DialTCP(conn *tcp.Conn, localPort uint16, addrp netip.AddrP
// StartQuery starts an ARP query for addresses in this network.
// On finishing query MAC is set and thus the StackPort will allow encapsulating
// data on that connection.
err = s.arp.StartQuery(mac, ip[:])
err = s.arpt.startQuery(mac, ip[:], &s.arp)
if err != nil {
return err
}
@@ -576,7 +591,7 @@ func (s *StackAsync) StartResolveHardwareAddress6(ip netip.Addr) error {
return lneto.ErrUnsupported
}
addr := ip.As4()
return s.arp.StartQuery(nil, addr[:])
return s.arp.StartQuery(addr[:], false)
}
// ResultResolveHardwareAddress6
@@ -587,7 +602,7 @@ func (s *StackAsync) ResultResolveHardwareAddress6(ip netip.Addr) (hw [6]byte, e
return hw, lneto.ErrUnsupported
}
addr := ip.As4()
hwslice, err := s.arp.QueryResult(addr[:])
hwslice, err := s.arp.CacheLookup(addr[:])
if err != nil {
return hw, err
} else if len(hwslice) != 6 {
@@ -604,7 +619,7 @@ func (s *StackAsync) DiscardResolveHardwareAddress6(ip netip.Addr) error {
return lneto.ErrUnsupported
}
addr := ip.As4()
return s.arp.DiscardQuery(addr[:])
return s.arp.CacheRemove(addr[:])
}
type DHCPResults struct {
@@ -648,7 +663,7 @@ func (stack *StackAsync) AssimilateDHCPResults(results *DHCPResults) error {
stack.mu.Lock()
defer stack.mu.Unlock()
if results.Subnet.IsValid() {
stack.subnet = results.Subnet
stack.arpt.subnet = results.Subnet
}
if results.AssignedAddr.IsValid() {
err := stack.setIPAddr(results.AssignedAddr)