init

internal/protocol/protocol.go

@@ -0,0 +1,68 @@
+// Package protocol defines the LMVPN wire protocol structures and
+// constants. These mirror the server's definitions in
+// lmvpn_server/internal/vpn/{protocol,auth,tunnel}.go exactly.
+//
+// Wire format:
+//   - Text frames   = UTF-8 JSON control messages (with "type" field)
+//   - Binary frames = raw IPv4/IPv6 packets (no encapsulation header)
+package protocol
+
+import "time"
+
+// Message type strings exchanged over the WebSocket.
+const (
+	TypeAuth    = "auth"     // C→S: password credentials
+	TypeAuthOK  = "auth_ok"  // S→C: password auth succeeded
+	TypeAuthErr = "auth_err" // S→C: auth failed (then close)
+	TypeInit    = "init"     // S→C: tunnel parameters
+	TypeReady   = "ready"    // C→S: TUN configured, data plane ready
+	TypeError   = "error"    // S→C: handshake failure (then close)
+)
+
+// Timeout and limit constants matching the server (tunnel.go:16-23).
+const (
+	ReadTimeout    = 60 * time.Second // post-ready read deadline
+	WriteTimeout   = 10 * time.Second // per-write deadline
+	ReadyTimeout   = 30 * time.Second // client must send ready within this
+	PingPeriod     = 30 * time.Second // server ping interval
+	MaxMessageSize = 1 << 20          // 1 MiB max WebSocket message
+	MaxConnsPerUser = 3               // per-user concurrent connection cap
+	TokenExpiry    = 24 * time.Hour   // JWT validity
+)
+
+// InitMessage is sent by the server after auth + pre-checks pass.
+// (server: protocol.go:3-9, tunnel.go:126-137)
+type InitMessage struct {
+	Type     string `json:"type"`
+	IP       string `json:"ip"`        // assigned client IP (dotted-quad)
+	Prefix   int    `json:"prefix"`    // subnet prefix length (e.g. 24)
+	MTU      int    `json:"mtu"`       // TUN device MTU (e.g. 1420)
+	ServerIP string `json:"server_ip"` // server's tunnel IP (peer/gateway)
+}
+
+// ControlMessage is the generic text control message.
+// (server: protocol.go:11-13)
+type ControlMessage struct {
+	Type    string `json:"type"`
+	Message string `json:"message,omitempty"`
+}
+
+// AuthMessage is sent by the client for password authentication.
+// (server: auth.go:17-21)
+type AuthMessage struct {
+	Type     string `json:"type"`
+	Username string `json:"username"`
+	Password string `json:"password"`
+}
+
+// AuthResponse is the server's reply to an AuthMessage.
+// (server: auth.go:23-26)
+type AuthResponse struct {
+	Type    string `json:"type"`
+	Message string `json:"message,omitempty"`
+}
+
+// IsError reports whether a control message type indicates failure.
+func IsError(msgType string) bool {
+	return msgType == TypeAuthErr || msgType == TypeError
+}