Scaffolding for generic (non-UDP) wire messages. (#132)

message.go

@@ -0,0 +1,76 @@
+package dilithium
+
+import (
+	"github.com/openziti/dilithium/util"
+	"github.com/pkg/errors"
+)
+
+type WireMessage struct {
+	Seq int32
+	Mt  messageType
+	buf *Buffer
+}
+
+type messageType uint8
+
+const (
+	// 0x0 ... 0x7
+	HELLO messageType = iota
+	ACK
+	DATA
+	KEEPALIVE
+	CLOSE
+)
+
+const messageTypeMask = byte(0x7)
+
+type messageFlag uint8
+
+const (
+	// 0x8 ... 0x80
+	RTT        messageFlag = 0x8
+	INLINE_ACK messageFlag = 0x10
+)
+
+const dataStart = 7
+
+func readWireMessage(t Transport, pool *Pool) (wm *WireMessage, err error) {
+	buf := pool.Get()
+	var n int
+	n, err = t.Read(buf.Data)
+	if err != nil {
+		return nil, errors.Wrap(err, "peer read")
+	}
+	buf.Used = uint32(n)
+
+	wm, err = decodeHeader(buf)
+	if err != nil {
+		return nil, errors.Wrap(err, "decode header")
+	}
+
+	return
+}
+
+func (wm *WireMessage) encodeHeader(dataSize uint16) (*WireMessage, error) {
+	if wm.buf.Size < uint32(dataStart+dataSize) {
+		return nil, errors.Errorf("short buffer for encode [%d < %d]", wm.buf.Size, dataStart+dataSize)
+	}
+	util.WriteInt32(wm.buf.Data[0:4], wm.Seq)
+	wm.buf.Data[4] = byte(wm.Mt)
+	util.WriteUint16(wm.buf.Data[5:dataStart], dataSize)
+	wm.buf.Used = uint32(dataStart + dataSize)
+	return wm, nil
+}
+
+func decodeHeader(buf *Buffer) (*WireMessage, error) {
+	size := util.ReadUint16(buf.Data[5:dataStart])
+	if uint32(dataStart+size) > buf.Used {
+		return nil, errors.Errorf("short buffer read [%d != %d]", buf.Size, dataStart+size)
+	}
+	wm := &WireMessage{
+		Seq: util.ReadInt32(buf.Data[0:4]),
+		Mt:  messageType(buf.Data[4]),
+		buf: buf,
+	}
+	return wm, nil
+}