Update README.md

[rbdr/mobius] / hotline / handshake.go

diff --git a/hotline/handshake.go b/hotline/handshake.go
index 66bf643dfbb921104a7e83afa1d13dff77ab2c9e..c54359e0e648acf41b16c3ad3cab8cfc6e73018a 100644 (file)
--- a/hotline/handshake.go
+++ b/hotline/handshake.go
@@ -4,17 +4,12 @@ import (
        "bytes"
        "encoding/binary"
        "errors"
        "bytes"
        "encoding/binary"
        "errors"

-       "net"
+       "fmt"
+       "io"

 )
 
 )
 

-type handshake struct {
-       Protocol    [4]byte // Must be 0x54525450 TRTP
-       SubProtocol [4]byte
-       Version     [2]byte // Always 1
-       SubVersion  [2]byte
-}
-
-// Handshake
+// Hotline handshake process
+//

 // 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,
 // 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,


@@ -33,17 +28,60 @@ type handshake struct {
 // Description         Size    Data    Note
 // Protocol ID         4               TRTP
 // Error code          4                               Error code returned by the server (0 = no error)
 // 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 {
+
+type handshake struct {
+       Protocol    [4]byte // Must be 0x54525450 TRTP
+       SubProtocol [4]byte // Must be 0x484F544C HOTL
+       Version     [2]byte // Always 1 (?)
+       SubVersion  [2]byte // Always 2 (?)
+}
+
+// Write implements the io.Writer interface for handshake.
+func (h *handshake) Write(p []byte) (n int, err error) {
+       if len(p) != handshakeSize {
+               return 0, errors.New("invalid handshake size")
+       }
+
+       _ = binary.Read(bytes.NewBuffer(p), binary.BigEndian, h)
+
+       return len(p), nil
+}
+
+// Valid checks if the handshake contains valid protocol and sub-protocol IDs.
+func (h *handshake) Valid() bool {
+       return h.Protocol == trtp && h.SubProtocol == hotl
+}
+
+var (
+       // trtp represents the Protocol ID "TRTP" in hex
+       trtp = [4]byte{0x54, 0x52, 0x54, 0x50}
+
+       // hotl represents the Sub-protocol ID "HOTL" in hex
+       hotl = [4]byte{0x48, 0x4F, 0x54, 0x4C}
+
+       // handshakeResponse represents the server's response after a successful handshake
+       // Response with "TRTP" and no error code
+       handshakeResponse = [8]byte{0x54, 0x52, 0x54, 0x50, 0x00, 0x00, 0x00, 0x00}
+)
+
+const handshakeSize = 12
+
+// performHandshake performs the handshake process.
+func performHandshake(rw io.ReadWriter) error {

        var h handshake
        var h handshake

-       r := bytes.NewReader(buf)
-       if err := binary.Read(r, binary.BigEndian, &h); err != nil {
-               return err
+
+       // Copy exactly handshakeSize bytes from rw to handshake
+       if _, err := io.CopyN(&h, rw, handshakeSize); err != nil {
+               return fmt.Errorf("failed to read handshake data: %w", err)
+       }
+
+       if !h.Valid() {
+               return errors.New("invalid protocol or sub-protocol in handshake")

        }
 
        }
 

-       if h.Protocol != [4]byte{0x54, 0x52, 0x54, 0x50} {
-               return errors.New("invalid handshake")
+       if _, err := rw.Write(handshakeResponse[:]); err != nil {
+               return fmt.Errorf("error sending handshake response: %w", err)

        }
 
        }
 

-       _, err := conn.Write([]byte{84, 82, 84, 80, 0, 0, 0, 0})
-       return err
+       return nil

 }
 }