teraWeb/backend/internal/directstream/session_event.go

package directstream

import (
	"errors"
	"fmt"
	"net"
	"strings"
	"time"
)

const (
	SessionEventConnected    = "connected"
	SessionEventDisconnected = "disconnected"
)

// SessionEvent is emitted by tera-sessiond only after a ticket-bound Direct
// Mode attachment has been authenticated. Source is the normalized client IP
// supplied by the trusted same-origin gateway.
type SessionEvent struct {
	Type      string    `json:"type"`
	Source    string    `json:"source"`
	Timestamp time.Time `json:"timestamp"`
}

func validateSessionEvent(event SessionEvent) error {
	if event.Type != SessionEventConnected && event.Type != SessionEventDisconnected {
		return errors.New("direct stream session event type is invalid")
	}
	if net.ParseIP(strings.TrimSpace(event.Source)) == nil {
		return errors.New("direct stream session event source must be an IP address")
	}
	if event.Timestamp.IsZero() {
		return errors.New("direct stream session event timestamp is required")
	}
	return nil
}

// SessionEventMessage is shared by the WebSocket welcome frame and the
// authoritative per-port log writer so the operator sees the same identity
// data that is retained for the channel.
func SessionEventMessage(claims TicketClaims, event SessionEvent) string {
	timestamp := event.Timestamp.UTC().Format(time.RFC3339)
	if event.Type == SessionEventConnected {
		return fmt.Sprintf(
			"Welcome to TERA CORA-X48 PRO K\nConnected from: %s\nSerial channel: %s\nUser: %s\nAccess: %s\nSession: %s\nConnected at: %s",
			event.Source, claims.Channel, claims.Actor, claims.Access, claims.SessionID, timestamp,
		)
	}
	return fmt.Sprintf(
		"TERA CORA-X48 PRO K session disconnected\nConnected from: %s\nSerial channel: %s\nUser: %s\nAccess: %s\nSession: %s\nDisconnected at: %s",
		event.Source, claims.Channel, claims.Actor, claims.Access, claims.SessionID, timestamp,
	)
}

func welcomeFrame(claims TicketClaims, event SessionEvent) []byte {
	message := strings.ReplaceAll(SessionEventMessage(claims, event), "\n", "\r\n")
	return []byte("\r\n" + message + "\r\n\r\n")
}