Misc cleanup

* Removed some unnecessary user of pointers
* Removed dead cruft
* Reorganized code

1 files changed, 49 insertions, 0 deletions

diff --git a/hotline/handshake.go b/hotline/handshake.go
new file mode 100644
index 0000000..66bf643
--- /dev/null
+++ b/hotline/handshake.go
@@ -0,0 +1,49 @@
+package hotline
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"net"
+)
+
+type handshake struct {
+	Protocol    [4]byte // Must be 0x54525450 TRTP
+	SubProtocol [4]byte
+	Version     [2]byte // Always 1
+	SubVersion  [2]byte
+}
+
+// Handshake
+// After establishing TCP connection, both client and server start the handshake process
+// in order to confirm that each of them comply with requirements of the other.
+// The information provided in this initial data exchange identifies protocols,
+// and their versions, used in the communication. In the case where, after inspection,
+// the capabilities of one of the subjects do not comply with the requirements of the other,
+// the connection is dropped.
+//
+// The following information is sent to the server:
+// Description		Size 	Data	Note
+// Protocol ID		4		TRTP	0x54525450
+// Sub-protocol ID	4		HOTL	User defined
+// VERSION			2		1		Currently 1
+// Sub-version		2		2		User defined
+//
+// The server replies with the following:
+// Description		Size 	Data	Note
+// Protocol ID		4		TRTP
+// Error code		4				Error code returned by the server (0 = no error)
+func Handshake(conn net.Conn, buf []byte) error {
+	var h handshake
+	r := bytes.NewReader(buf)
+	if err := binary.Read(r, binary.BigEndian, &h); err != nil {
+		return err
+	}
+
+	if h.Protocol != [4]byte{0x54, 0x52, 0x54, 0x50} {
+		return errors.New("invalid handshake")
+	}
+
+	_, err := conn.Write([]byte{84, 82, 84, 80, 0, 0, 0, 0})
+	return err
+}