showbridge-go/udp-multicast.go

package showbridge

import (
	"fmt"
	"log/slog"
	"net"
	"time"

	"github.com/jwetzell/showbridge-go/internal/config"
)

type UDPMulticast struct {
	config config.ModuleConfig
	conn   *net.UDPConn
	router *Router
	Addr   *net.UDPAddr
}

func init() {
	RegisterModule(ModuleRegistration{
		Type: "net.udp.multicast",
		New: func(config config.ModuleConfig) (Module, error) {
			params := config.Params
			ip, ok := params["ip"]

			if !ok {
				return nil, fmt.Errorf("net.udp.client requires am ip parameter")
			}

			ipString, ok := ip.(string)

			if !ok {
				return nil, fmt.Errorf("net.udp.client ip must be a string")
			}

			port, ok := params["port"]
			if !ok {
				return nil, fmt.Errorf("net.udp.client requires a port parameter")
			}

			portNum, ok := port.(float64)

			if !ok {
				return nil, fmt.Errorf("net.udp.client port must be a number")
			}

			addr, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", ipString, uint16(portNum)))
			if err != nil {
				return nil, err
			}
			return &UDPMulticast{config: config, Addr: addr}, nil
		},
	})
}

func (um *UDPMulticast) Id() string {
	return um.config.Id
}

func (um *UDPMulticast) Type() string {
	return um.config.Type
}

func (um *UDPMulticast) RegisterRouter(router *Router) {
	um.router = router
}

func (um *UDPMulticast) Run() error {

	client, err := net.ListenMulticastUDP("udp", nil, um.Addr)
	if err != nil {
		return err
	}
	defer client.Close()

	um.conn = client

	buffer := make([]byte, 2048)
	for {
		select {
		case <-um.router.Context.Done():
			// TODO(jwetzell): cleanup?
			slog.Debug("router context done in module", "id", um.config.Id)
			return nil
		default:
			um.conn.SetDeadline(time.Now().Add(time.Millisecond * 200))

			numBytes, _, err := um.conn.ReadFromUDP(buffer)
			if err != nil {
				//NOTE(jwetzell) we hit deadline
				if opErr, ok := err.(*net.OpError); ok && opErr.Timeout() {
					continue
				}
				return err
			}

			if numBytes > 0 {
				message := buffer[:numBytes]

				if um.router != nil {
					um.router.HandleInput(um.config.Id, message)
				} else {
					slog.Error("net.udp.multicast has no router", "id", um.config.Id)
				}
			}
		}
	}
}

func (um *UDPMulticast) Output(payload any) error {

	payloadBytes, ok := payload.([]byte)
	if !ok {
		return fmt.Errorf("net.udp.multicast can only output bytes")
	}

	if um.conn == nil {
		return fmt.Errorf("net.udp.multicast connection is not setup")
	}

	_, err := um.conn.Write(payloadBytes)
	return err
}