func()

in ptp/ptp4u/server/worker.go [67:141]

• 58 lines of code
• 17 McCabe index (conditional complexity)

func (s *sendWorker) listen() (eventFD, generalFD int, err error) {
	// socket domain differs depending whether we are listening on ipv4 or ipv6
	domain := unix.AF_INET6
	if s.config.IP.To4() != nil {
		domain = unix.AF_INET
	}
	// set up event connection
	eventFD, err = unix.Socket(domain, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
	if err != nil {
		return -1, -1, fmt.Errorf("creating event socket error: %w", err)
	}
	sockAddrAnyPort := timestamp.IPToSockaddr(s.config.IP, 0)

	// set SO_REUSEPORT so we can potentially trace network path from same source port.
	// needs to be set before we bind to a port.
	if err = unix.SetsockoptInt(eventFD, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
		return -1, -1, fmt.Errorf("failed to set SO_REUSEPORT on event socket: %w", err)
	}
	// bind to any ephemeral port
	if err := unix.Bind(eventFD, sockAddrAnyPort); err != nil {
		return -1, -1, fmt.Errorf("unable to bind event socket connection: %w", err)
	}

	// get local port we'll send packets from
	localSockAddr, err := unix.Getsockname(eventFD)
	if err != nil {
		return -1, -1, fmt.Errorf("unable to find local ip: %w", err)
	}
	switch v := localSockAddr.(type) {
	case *unix.SockaddrInet4:
		log.Infof("Started worker#%d event on [%v]:%d", s.id, net.IP(v.Addr[:]), v.Port)
	case *unix.SockaddrInet6:
		log.Infof("Started worker#%d event on [%v]:%d", s.id, net.IP(v.Addr[:]), v.Port)
	default:
		log.Errorf("Unexpected local addr type %T", v)
	}

	if err = enableDSCP(eventFD, s.config.IP, s.config.DSCP); err != nil {
		return -1, -1, fmt.Errorf("setting DSCP on event socket: %w", err)
	}

	// Syncs sent from event port, so need to turn on timestamping here
	switch s.config.TimestampType {
	case timestamp.HWTIMESTAMP:
		if err := timestamp.EnableHWTimestamps(eventFD, s.config.Interface); err != nil {
			return -1, -1, fmt.Errorf("failed to enable RX hardware timestamps: %w", err)
		}
	case timestamp.SWTIMESTAMP:
		if err := timestamp.EnableSWTimestamps(eventFD); err != nil {
			return -1, -1, fmt.Errorf("unable to enable RX software timestamps: %w", err)
		}
	default:
		return -1, -1, fmt.Errorf("unrecognized timestamp type: %s", s.config.TimestampType)
	}

	// set up general connection
	generalFD, err = unix.Socket(domain, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
	if err != nil {
		return -1, -1, fmt.Errorf("creating general socket error: %w", err)
	}
	// set SO_REUSEPORT so we can potentially trace network path from same source port.
	// needs to be set before we bind to a port.
	if err = unix.SetsockoptInt(generalFD, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
		return -1, -1, fmt.Errorf("failed to set SO_REUSEPORT on general socket: %w", err)
	}
	// bind to any ephemeral port
	if err := unix.Bind(generalFD, sockAddrAnyPort); err != nil {
		return -1, -1, fmt.Errorf("binding event socket connection: %w", err)
	}
	// enable DSCP
	if err = enableDSCP(generalFD, s.config.IP, s.config.DSCP); err != nil {
		return -1, -1, fmt.Errorf("setting DSCP on general socket: %w", err)
	}
	return
}