Add new reject channel to router so we can send back rejected packets to adapter (e.g. for ICMPv6 Packet Too Big), implement ICMPv6 PTB in TUN/TAP instead of router

src/tuntap/tun.go

@@ -11,6 +11,8 @@ import (
 	"time"
 
 	"github.com/gologme/log"
+	"golang.org/x/net/icmp"
+	"golang.org/x/net/ipv6"
 
 	"github.com/songgao/packets/ethernet"
 	"github.com/yggdrasil-network/water"
@@ -64,10 +66,10 @@ func (tun *TunAdapter) IsTAP() bool {
 }
 
 // Initialises the TUN/TAP adapter.
-func (tun *TunAdapter) Init(config *config.NodeState, log *log.Logger, send chan<- []byte, recv <-chan []byte) {
+func (tun *TunAdapter) Init(config *config.NodeState, log *log.Logger, send chan<- []byte, recv <-chan []byte, reject <-chan yggdrasil.RejectedPacket) {
 	tun.config = config
 	tun.log = log
-	tun.Adapter.Init(config, log, send, recv)
+	tun.Adapter.Init(config, log, send, recv, reject)
 	tun.icmpv6.Init(tun)
 	go func() {
 		for {
@@ -146,7 +148,32 @@ func (tun *TunAdapter) Start(a address.Address, s address.Subnet) error {
 // host operating system.
 func (tun *TunAdapter) Write() error {
 	for {
-		data := <-tun.Recv
+		select {
+		case reject := <-tun.Reject:
+			switch reject.Reason {
+			case yggdrasil.PacketTooBig:
+				if mtu, ok := reject.Detail.(int); ok {
+					// Create the Packet Too Big response
+					ptb := &icmp.PacketTooBig{
+						MTU:  int(mtu),
+						Data: reject.Packet,
+					}
+
+					// Create the ICMPv6 response from it
+					icmpv6Buf, err := CreateICMPv6(
+						reject.Packet[8:24], reject.Packet[24:40],
+						ipv6.ICMPTypePacketTooBig, 0, ptb)
+
+					// Send the ICMPv6 response back to the TUN/TAP adapter
+					if err == nil {
+						tun.iface.Write(icmpv6Buf)
+					}
+				}
+				fallthrough
+			default:
+				continue
+			}
+		case data := <-tun.Recv:
 			if tun.iface == nil {
 				continue
 			}
@@ -246,6 +273,7 @@ func (tun *TunAdapter) Write() error {
 			util.PutBytes(data)
 		}
 	}
+}
 
 // Reads any packets that are waiting on the TUN/TAP adapter. If the adapter
 // is running in TAP mode then the ethernet headers will automatically be

src/yggdrasil/adapter.go

@@ -13,12 +13,13 @@ type Adapter struct {
 	Core        *Core
 	Send        chan<- []byte
 	Recv        <-chan []byte
+	Reject      <-chan RejectedPacket
 	Reconfigure chan chan error
 }
 
 // Defines the minimum required functions for an adapter type
 type adapterImplementation interface {
-	Init(*config.NodeState, *log.Logger, chan<- []byte, <-chan []byte)
+	Init(*config.NodeState, *log.Logger, chan<- []byte, <-chan []byte, <-chan RejectedPacket)
 	Name() string
 	MTU() int
 	IsTAP() bool
@@ -29,9 +30,10 @@ type adapterImplementation interface {
 }
 
 // Initialises the adapter.
-func (adapter *Adapter) Init(config *config.NodeState, log *log.Logger, send chan<- []byte, recv <-chan []byte) {
+func (adapter *Adapter) Init(config *config.NodeState, log *log.Logger, send chan<- []byte, recv <-chan []byte, reject <-chan RejectedPacket) {
 	log.Traceln("Adapter setup - given channels:", send, recv)
 	adapter.Send = send
 	adapter.Recv = recv
+	adapter.Reject = reject
 	adapter.Reconfigure = make(chan chan error, 1)
 }

src/yggdrasil/router.go

@@ -44,6 +44,7 @@ type router struct {
 	tun         adapterImplementation  // TUN/TAP adapter
 	recv        chan<- []byte          // place where the tun pulls received packets from
 	send        <-chan []byte          // place where the tun puts outgoing packets
+	reject      chan<- RejectedPacket  // place where we send error packets back to tun
 	reset       chan struct{}          // signal that coords changed (re-init sessions/dht)
 	admin       chan func()            // pass a lambda for the admin socket to query stuff
 	cryptokey   cryptokey
@@ -56,6 +57,19 @@ type router_recvPacket struct {
 	sinfo *sessionInfo
 }
 
+type RejectedPacketReason int
+
+const (
+	// The router rejected the packet because it is too big for the session
+	PacketTooBig = 1 + iota
+)
+
+type RejectedPacket struct {
+	Reason RejectedPacketReason
+	Packet []byte
+	Detail interface{}
+}
+
 // Initializes the router struct, which includes setting up channels to/from the tun/tap.
 func (r *router) init(core *Core) {
 	r.core = core
@@ -103,8 +117,10 @@ func (r *router) init(core *Core) {
 	r.toRecv = make(chan router_recvPacket, 32)
 	recv := make(chan []byte, 32)
 	send := make(chan []byte, 32)
+	reject := make(chan RejectedPacket, 32)
 	r.recv = recv
 	r.send = send
+	r.reject = reject
 	r.reset = make(chan struct{}, 1)
 	r.admin = make(chan func(), 32)
 	r.nodeinfo.init(r.core)
@@ -112,7 +128,7 @@ func (r *router) init(core *Core) {
 	r.nodeinfo.setNodeInfo(r.core.config.Current.NodeInfo, r.core.config.Current.NodeInfoPrivacy)
 	r.core.config.Mutex.RUnlock()
 	r.cryptokey.init(r.core)
-	r.tun.Init(&r.core.config, r.core.log, send, recv)
+	r.tun.Init(&r.core.config, r.core.log, send, recv, reject)
 }
 
 // Starts the mainLoop goroutine.
@@ -303,25 +319,18 @@ func (r *router) sendPacket(bs []byte) {
 		// Generate an ICMPv6 Packet Too Big for packets larger than session MTU
 		if len(bs) > int(sinfo.getMTU()) {
 			// Get the size of the oversized payload, up to a max of 900 bytes
-			/*window := 900
+			window := 900
 			if int(sinfo.getMTU()) < window {
 				window = int(sinfo.getMTU())
 			}
 
-			// Create the Packet Too Big response
-			ptb := &icmp.PacketTooBig{
-				MTU:  int(sinfo.getMTU()),
-				Data: bs[:window],
+			// Send the error back to the adapter
+			r.reject <- RejectedPacket{
+				Reason: PacketTooBig,
+				Packet: bs[:window],
+				Detail: int(sinfo.getMTU()),
 			}
 
-			// Create the ICMPv6 response from it
-			icmpv6Buf, err := CreateICMPv6(
-				bs[8:24], bs[24:40],
-				ipv6.ICMPTypePacketTooBig, 0, ptb)
-			if err == nil {
-				r.recv <- icmpv6Buf
-			}*/
-
 			// Don't continue - drop the packet
 			return
 		}