feature: ipv4 broadcast support and bugfix for reset connection reset of IPv4+IPv6 stacks (#139)

* feature: ipv4 broadcast support

* stackip4 method receiver varname

internet/stack-ip4.go

@@ -22,34 +22,35 @@ type StackIPv4 struct {
 }
 
 func (stackip4 *StackIPv4) Reset(vld *lneto.Validator, maxNodes int) error {
+	stackip4.connID++
 	stackip4.reset4(vld, maxNodes)
 	return nil
 }
 
-func (stackip *StackIPv4) ConnectionID() *uint64 {
+func (stackip4 *StackIPv4) ConnectionID() *uint64 {
-	return &stackip.connID
+	return &stackip4.connID
 }
 
-func (stackip *StackIPv4) Protocol() uint64 {
+func (stackip4 *StackIPv4) Protocol() uint64 {
 	return uint64(ethernet.TypeIPv4)
 }
 
-func (stackip *StackIPv4) LocalPort() uint16 { return 0 }
+func (stackip4 *StackIPv4) LocalPort() uint16 { return 0 }
 
-func (stackip *StackIPv4) SetLogger(logger *slog.Logger) {
+func (stackip4 *StackIPv4) SetLogger(logger *slog.Logger) {
-	stackip.stackip4.handlers.log = logger
+	stackip4.stackip4.handlers.log = logger
 }
 
-func (stackip *StackIPv4) Demux(carrierData []byte, offset int) error {
+func (stackip4 *StackIPv4) Demux(carrierData []byte, offset int) error {
 	debugLog("ip:demux")
-	return stackip.stackip4.demux4(carrierData, offset)
+	return stackip4.stackip4.demux4(carrierData, offset)
 }
 
-func (stackip *StackIPv4) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (n int, err error) {
+func (stackip4 *StackIPv4) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (n int, err error) {
 	if offsetToFrame != offsetToIP {
 		return 0, lneto.ErrBug
 	}
-	return stackip.stackip4.encapsulate4(carrierData, offsetToIP)
+	return stackip4.stackip4.encapsulate4(carrierData, offsetToIP)
 }
 
 type stackip4 struct {
@@ -58,6 +59,7 @@ type stackip4 struct {
 	ipID            uint16
 	ip4             [4]byte
 	acceptMulticast bool
+	acceptBroadcast bool
 }
 
 func (si4 *stackip4) reset4(vld *lneto.Validator, maxNodes int) {
@@ -86,6 +88,10 @@ func (si4 *stackip4) IsRegistered4(proto lneto.IPProto) bool {
 func (si4 *stackip4) SetAcceptMulticast4(accept bool) {
 	si4.acceptMulticast = accept
 }
+func (si4 *stackip4) SetAcceptBroadcast4(accept bool) {
+	si4.acceptBroadcast = accept
+}
+
 func (si4 *stackip4) Addr4() [4]byte { return si4.ip4 }
 func (si4 *stackip4) SetAddr4(ip4 [4]byte) {
 	si4.ip4 = ip4
@@ -100,8 +106,13 @@ func (si4 *stackip4) demux4(carrierData []byte, offset int) error {
 		return err
 	}
 	dst := ifrm.DestinationAddr()
-	if si4.ip4 != ([4]byte{}) && *dst != si4.ip4 {
+	if si4.ip4 != ([4]byte{}) && *dst != si4.ip4 { // Accept all packets when IP zeroed.
-		if !si4.acceptMulticast || !internal.IsMulticastIPAddr(dst[:]) {
+		switch {
+		case si4.acceptMulticast && ipv4.IsMulticast(*dst):
+			// accept multicast.
+		case si4.acceptBroadcast && ipv4.IsBroadcast(*dst):
+			// accept broadcast.
+		default:
 			si4.handlers.debug("ip:not-for-us")
 			return lneto.ErrPacketDrop // Not meant for us.
 		}

internet/stack-ip6.go

@@ -19,35 +19,36 @@ type StackIPv6 struct {
 	stackip6
 }
 
-func (stackip4 *StackIPv6) Reset(vld *lneto.Validator, maxNodes int) error {
+func (stackip6 *StackIPv6) Reset(vld *lneto.Validator, maxNodes int) error {
-	stackip4.reset6(vld, maxNodes)
+	stackip6.connID++
+	stackip6.reset6(vld, maxNodes)
 	return nil
 }
 
-func (stackip *StackIPv6) ConnectionID() *uint64 {
+func (stackip6 *StackIPv6) ConnectionID() *uint64 {
-	return &stackip.connID
+	return &stackip6.connID
 }
 
-func (stackip *StackIPv6) Protocol() uint64 {
+func (stackip6 *StackIPv6) Protocol() uint64 {
 	return uint64(ethernet.TypeIPv6)
 }
 
-func (stackip *StackIPv6) LocalPort() uint16 { return 0 }
+func (stackip6 *StackIPv6) LocalPort() uint16 { return 0 }
 
-func (stackip *StackIPv6) SetLogger(logger *slog.Logger) {
+func (stackip6 *StackIPv6) SetLogger(logger *slog.Logger) {
-	stackip.stackip6.handlers.log = logger
+	stackip6.stackip6.handlers.log = logger
 }
 
-func (stackip *StackIPv6) Demux(carrierData []byte, offset int) error {
+func (stackip6 *StackIPv6) Demux(carrierData []byte, offset int) error {
 	debugLog("ip:demux")
-	return stackip.stackip6.demux6(carrierData, offset)
+	return stackip6.stackip6.demux6(carrierData, offset)
 }
 
-func (stackip *StackIPv6) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (n int, err error) {
+func (stackip6 *StackIPv6) Encapsulate(carrierData []byte, offsetToIP, offsetToFrame int) (n int, err error) {
 	if offsetToFrame != offsetToIP {
 		return 0, lneto.ErrBug
 	}
-	return stackip.stackip6.encapsulate6(carrierData, offsetToIP)
+	return stackip6.stackip6.encapsulate6(carrierData, offsetToIP)
 }
 
 type stackip6 struct {
@@ -55,6 +56,7 @@ type stackip6 struct {
 	vld             *lneto.Validator
 	ip6             [16]byte
 	acceptMulticast bool
+	acceptBroadcast bool
 }
 
 func (si6 *stackip6) Register6(h lneto.StackNode) error {

ipv4/definitions.go

@@ -18,6 +18,17 @@ func IsMulticast(addr [4]byte) bool {
 	return addr[0]&0xf0 == 0xe0
 }
 
+// IsBroadcast reports whether addr is the limited broadcast address
+// 255.255.255.255 used to address all hosts on the local network segment
+// as defined in [RFC919]. It does not detect directed (subnet) broadcast
+// addresses, which depend on the network mask and cannot be determined from
+// the address alone.
+//
+// [RFC919]: https://datatracker.ietf.org/doc/html/rfc919
+func IsBroadcast(addr [4]byte) bool {
+	return addr == [4]byte{255, 255, 255, 255}
+}
+
 // IsLinkLocal reports whether addr is within the IPv4 link-local prefix
 // 169.254.0.0/16 reserved for dynamic link-local configuration as defined in [RFC3927].
 //

x/xnet/stack-async.go

@@ -103,6 +103,8 @@ type StackConfig struct {
 	MTU uint16
 	// Accept multicast ethernet and IP packets. Needed for MDNS.
 	AcceptMulticast bool
+	// Accept broadcast IPv4 packets. Needed for managing access points and DHCPv4 servers.
+	AcceptIPv4Broadcast bool
 }
 
 func (cfg *StackConfig) id() uint16 {
@@ -234,7 +236,7 @@ func (s *StackAsync) Reset(cfg StackConfig) (err error) {
 	}
 	s.ip4.SetAddr4(cfg.StaticAddress4)
 	s.setAcceptMulticast4(cfg.AcceptMulticast)
-
+	s.ip4.SetAcceptBroadcast4(cfg.AcceptIPv4Broadcast)
 	s.arpt.passivePeers = uint8(cfg.PassivePeers)
 	err = s.resetARP()
 	if err != nil {