add gorilla websocket module, build tran protocol model

go.mod

@@ -5,6 +5,7 @@ go 1.17
 require (
 	github.com/charmbracelet/bubbles v0.10.2
 	github.com/charmbracelet/lipgloss v0.4.0
+	github.com/gorilla/websocket v1.4.2
 )
 
 require (

go.sum

@@ -9,6 +9,8 @@ github.com/charmbracelet/lipgloss v0.4.0 h1:768h64EFkGUr8V5yAKV7/Ta0NiVceiPaV+Pp
 github.com/charmbracelet/lipgloss v0.4.0/go.mod h1:vmdkHvce7UzX6xkyf4cca8WlwdQ5RQr8fzta+xl7BOM=
 github.com/containerd/console v1.0.2 h1:Pi6D+aZXM+oUw1czuKgH5IJ+y0jhYcwBJfx5/Ghn9dE=
 github.com/containerd/console v1.0.2/go.mod h1:ytZPjGgY2oeTkAONYafi2kSj0aYggsf8acV1PGKCbzQ=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
 github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=

models/protocol/transfer.go

@@ -0,0 +1,107 @@
+package protocol
+
+import (
+	"fmt"
+	"net"
+	"strings"
+)
+
+// TransferMessageType specifies the message type for the messages in the transfer protocol.
+type TransferMessageType int
+
+const (
+	TransferError TransferMessageType = iota // An error has occured in transferProtocol
+	ReceiverHandshake          // Receiver exchange its IP via the tranx server to the sender
+	SenderHandshake   		   // Sender exchanges IP, port and payload size to the receiver via the tranx server
+	ReceiverDirectCommunication
+	SenderDirectAck            // Sender ACKs the request for direct communication
+	ReceiverRelayCommunication // Receiver has tried to probe the sender but cannot find it on the subnet, relay communication will be used
+	SenderRelayAck             // Sender ACKs the request for relay communication
+	ReceiverRequestPayload     // Receiver request the payload from the sender
+	SenderPayloadSent          // Sender announces that the entire file has been transfered
+	ReceiverPayloadAck         // Receiver ACKs that is has received the payload
+	SenderClosing              // Sender announces that it is closing the connection
+	ReceiverClosingAck         // Receiver ACKs the closing of the connection
+)
+
+// TransferMessage specifies a message in the transfer protocol.
+type TransferMessage struct {
+	Type    TransferMessageType `json:"type"`
+	Payload interface{}         `json:"payload,omitempty"`
+}
+
+func (t TransferMessage) Bytes() []byte {
+	return []byte(fmt.Sprintf("%v", t))
+}
+
+type ReceiverHandshakePayload struct {
+	IP net.IP `json:"ip"`
+}
+
+// SenderHandshakePayload specifies a payload type for announcing the payload size.
+type SenderHandshakePayload struct {
+	IP          net.IP `json:"ip"`
+	Port        int    `json:"port"`
+	PayloadSize int64  `json:"payload_size"`
+}
+
+type WrongMessageTypeError struct {
+	expected []TransferMessageType
+	got      TransferMessageType
+}
+
+func NewWrongMessageTypeError(expected []TransferMessageType, got TransferMessageType) *WrongMessageTypeError {
+	return &WrongMessageTypeError{
+		expected: expected,
+		got:      got,
+	}
+}
+
+func (e *WrongMessageTypeError) Error() string {
+	var expectedMessageTypes []string
+
+	for _, expectedType := range e.expected {
+		expectedMessageTypes = append(expectedMessageTypes, expectedType.Name())
+	}
+
+	oneOfExpected := strings.Join(expectedMessageTypes, ", ")
+
+	return fmt.Sprintf("wrong message type, expected one of: (%s), got: (%s)", oneOfExpected, e.got.Name())
+}
+
+func (t TransferMessageType) Name() string {
+	switch t {
+		case TransferError:
+			return "TransferError"
+
+		case ReceiverHandshake:
+			return "ReceiverHandshake"
+
+		case SenderHandshake:
+			return "SenderHandshake"
+
+		case ReceiverRelayCommunication:
+			return "ReceiverRelayCommunication"
+
+		case SenderRelayAck:
+			return "SenderRelayAck"
+
+		case ReceiverRequestPayload:
+			return "ReceiverRequestPayload"
+
+		case SenderPayloadSent:
+			return "SenderPayloadSent"
+
+		case ReceiverPayloadAck:
+			return "ReceiverAckPayload"
+
+		case SenderClosing:
+			return "SenderClosing"
+
+		case ReceiverClosingAck:
+			return "ReceiverClosingAck"
+
+		default:
+			return ""
+	}
+}

models/protocol/tranx.go

@@ -0,0 +1,60 @@
+package protocol
+
+import (
+	"net"
+
+	"github.com/gorilla/websocket"
+)
+
+type TranxMessageType int
+
+const (
+	TranxToSenderBind TranxMessageType = iota // An ID for this connection is bound and communicated
+	SenderToTranxEstablish   // Sender has generated and hashed password
+	ReceiverToTranxEstablish // Passsword has been communicated to receiver who has hashed it
+	TranxToSenderReady       // Tranx announces to sender that receiver is connected
+	SenderToTranxPAKE        // Sender sends PAKE information to tranx
+	TranxToReceiverPAKE      // Tranx forwards PAKE information to receiver
+	ReceiverToTranxPAKE      // Receiver sends PAKE information to tranx
+	TranxToSenderPAKE        // Tranx forwards PAKE information to receiver
+	SenderToTranxSalt        // Sender sends cryptographic salt to tranx
+	TranxToReceiverSalt      // Rendevoux forwards cryptographic salt to receiver
+	ReceiverToTranxClose     // Receiver can connect directly to sender, close receiver connection -> close sender connection
+	SenderToTranxClose       // Transit sequence is completed, close sender connection -> close receiver connection
+)
+
+type TranxMessage struct {
+	Type    TranxMessageType `json:"type"`
+	Payload interface{}      `json:"payload"`
+}
+
+type TranxClient struct {
+	Conn *websocket.Conn
+	IP   net.IP
+}
+
+type TranxSender struct {
+	TranxClient
+	Port int
+}
+
+type TranxReceiver = TranxClient
+
+/* [💻 Receiver <-> Sender 💻] messages */
+
+type PasswordPayload struct {
+	Password string `json:"password"`
+}
+type PakePayload struct {
+	Bytes []byte `json:"pake_bytes"`
+}
+
+type SaltPayload struct {
+	Salt []byte `json:"salt"`
+}
+
+/* [Tranx -> Sender] messages */
+
+type TranxToSenderBindPayload struct {
+	ID int `json:"id"`
+}