Move DeliverNetworkPacket into separate goroutine

... as it may write in the same ironwood context as the reader
if packet destination is unknown or some other condition requires
replyWithReset

Thanks to @Arceliar for hint!

Signed-off-by: Vasyl Gello <[email protected]>

src/netstack/yggdrasil.go

@@ -15,19 +15,19 @@ import (
 )
 
 type YggdrasilNIC struct {
-	stack      *YggdrasilNetstack
-	ipv6rwc    *ipv6rwc.ReadWriteCloser
-	dispatcher stack.NetworkDispatcher
-	readBuf    []byte
-	writeBuf   []byte
+	stack        *YggdrasilNetstack
+	ipv6rwc      *ipv6rwc.ReadWriteCloser
+	dispatcher   stack.NetworkDispatcher
+	readBufChan  chan string
+	writeBuf     []byte
 }
 
 func (s *YggdrasilNetstack) NewYggdrasilNIC(ygg *core.Core) tcpip.Error {
 	rwc := ipv6rwc.NewReadWriteCloser(ygg)
 	mtu := rwc.MTU()
 	nic := &YggdrasilNIC{
 		ipv6rwc:  rwc,
-		readBuf:  make([]byte, mtu),
+		readBufChan: make(chan stack.PacketBuffer, 100),
 		writeBuf: make([]byte, mtu),
 	}
 	if err := s.stack.CreateNIC(1, nic); err != nil {
@@ -36,16 +36,22 @@ func (s *YggdrasilNetstack) NewYggdrasilNIC(ygg *core.Core) tcpip.Error {
 	go func() {
 		var rx int
 		var err error
+		readBuf := make([]byte, mtu)
 		for {
-			rx, err = nic.ipv6rwc.Read(nic.readBuf)
+			rx, err = nic.ipv6rwc.Read(readBuf)
 			if err != nil {
 				log.Println(err)
 				break
 			}
 			pkb := stack.NewPacketBuffer(stack.PacketBufferOptions{
 				Payload: buffer.MakeWithData(nic.readBuf[:rx]),
 			})
-			go nic.dispatcher.DeliverNetworkPacket(ipv6.ProtocolNumber, pkb)
+			nic.readBufChan <- pkb
+		}
+	}()
+	go func() {
+		for {
+			nic.dispatcher.DeliverNetworkPacket(ipv6.ProtocolNumber, <- nic.readBufChan)
 		}
 	}()
 	_, snet, err := net.ParseCIDR("0200::/7")