Golang net.FilePacketConn函数代码示例

// NewReusablePortPacketConn returns net.FileListener that created from a file discriptor for a socket with SO_REUSEPORT option.
func NewReusablePortPacketConn(proto, addr string) (l net.PacketConn, err error) {
	var (
		soType, fd int
		file       *os.File
		sockaddr   syscall.Sockaddr
	)

	if sockaddr, soType, err = getSockaddr(proto, addr); err != nil {
		return nil, err
	}

	if fd, err = syscall.Socket(soType, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP); err != nil {
		return nil, err
	}

	if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, reusePort, 1); err != nil {
		return nil, err
	}

	if err = syscall.Bind(fd, sockaddr); err != nil {
		return nil, err
	}

	// File Name get be nil
	file = os.NewFile(uintptr(fd), filePrefix+strconv.Itoa(os.Getpid()))
	if l, err = net.FilePacketConn(file); err != nil {
		return nil, err
	}

	if err = file.Close(); err != nil {
		return nil, err
	}

	return l, err
}

func mcastOpen(bindAddr net.IP, port int, ifname string) (*ipv4.PacketConn, *net.UDPConn, error) {
	s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
	if err != nil {
		log.Fatal(err)
	}
	if err := syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
		log.Fatal(err)
	}
	//syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEPORT, 1)
	if err := syscall.SetsockoptString(s, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, ifname); err != nil {
		log.Fatal(err)
	}

	lsa := syscall.SockaddrInet4{Port: port}
	copy(lsa.Addr[:], bindAddr.To4())

	if err := syscall.Bind(s, &lsa); err != nil {
		syscall.Close(s)
		log.Fatal(err)
	}
	f := os.NewFile(uintptr(s), "")
	c, err := net.FilePacketConn(f)
	f.Close()
	if err != nil {
		log.Fatal(err)
	}
	u := c.(*net.UDPConn)
	p := ipv4.NewPacketConn(c)

	return p, u, nil
}

func advert(_ net.PacketConn, src, dst net.IP, p *net.IPNet) error {
	s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
	if err != nil {
		return err
	}
	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEPORT, 1)
	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_BROADCAST, 1)
	pdst := dst
	if *useLimited && runtime.GOOS == "freebsd" {
		dst = directed(p)
		syscall.SetsockoptInt(s, syscall.IPPROTO_IP, 0x17, 1) // IP_ONESBCAST
	}
	sa := &syscall.SockaddrInet4{Port: *port}
	copy(sa.Addr[:], src.To4())
	if err := syscall.Bind(s, sa); err != nil {
		syscall.Close(s)
		return err
	}
	f := os.NewFile(uintptr(s), fmt.Sprintf("udp:%v->", src))
	c, err := net.FilePacketConn(f)
	f.Close()
	if err != nil {
		return err
	}
	defer c.Close()
	// If you are lucky, you can see that on some platform the
	// kernel sometimes transmits a wrong frame addressed to IPv4
	// limited broadcast address with some nexthop's link-layer
	// address on a broadcast-capable link.
	// In general, using BPF for transmitting IPv4 limited
	// broadcast addresses is a reasonable choice.
	_, err = c.WriteTo([]byte(fmt.Sprintf("%s-%v", runtime.GOOS, pdst)), &net.UDPAddr{IP: dst, Port: *port})
	return err
}

// ListenPacket listens for incoming ICMP packets addressed to
// address. See net.Dial for the syntax of address.
//
// For non-privileged datagram-oriented ICMP endpoints, network must
// be "udp4" or "udp6". The endpoint allows to read, write a few
// limited ICMP messages such as echo request and echo reply.
// Currently only Darwin and Linux support this.
//
// Examples:
//	ListenPacket("udp4", "192.168.0.1")
//	ListenPacket("udp4", "0.0.0.0")
//	ListenPacket("udp6", "fe80::1%en0")
//	ListenPacket("udp6", "::")
//
// For privileged raw ICMP endpoints, network must be "ip4" or "ip6"
// followed by a colon and an ICMP protocol number or name.
//
// Examples:
//	ListenPacket("ip4:icmp", "192.168.0.1")
//	ListenPacket("ip4:1", "0.0.0.0")
//	ListenPacket("ip6:ipv6-icmp", "fe80::1%en0")
//	ListenPacket("ip6:58", "::")
func ListenPacket(network, address string) (*PacketConn, error) {
	var family, proto int
	switch network {
	case "udp4":
		family, proto = syscall.AF_INET, iana.ProtocolICMP
	case "udp6":
		family, proto = syscall.AF_INET6, iana.ProtocolIPv6ICMP
	default:
		i := last(network, ':')
		switch network[:i] {
		case "ip4":
			proto = iana.ProtocolICMP
		case "ip6":
			proto = iana.ProtocolIPv6ICMP
		}
	}
	var cerr error
	var c net.PacketConn
	switch family {
	case syscall.AF_INET, syscall.AF_INET6:
		s, err := syscall.Socket(family, syscall.SOCK_DGRAM, proto)
		if err != nil {
			return nil, os.NewSyscallError("socket", err)
		}
		if runtime.GOOS == "darwin" && family == syscall.AF_INET {
			if err := syscall.SetsockoptInt(s, iana.ProtocolIP, sysIP_STRIPHDR, 1); err != nil {
				syscall.Close(s)
				return nil, os.NewSyscallError("setsockopt", err)
			}
		}
		sa, err := sockaddr(family, address)
		if err != nil {
			syscall.Close(s)
			return nil, err
		}
		if err := syscall.Bind(s, sa); err != nil {
			syscall.Close(s)
			return nil, os.NewSyscallError("bind", err)
		}
		f := os.NewFile(uintptr(s), "datagram-oriented icmp")
		c, cerr = net.FilePacketConn(f)
		f.Close()
	default:
		c, cerr = net.ListenPacket(network, address)
	}
	if cerr != nil {
		return nil, cerr
	}
	switch proto {
	case iana.ProtocolICMP:
		return &PacketConn{c: c, p4: ipv4.NewPacketConn(c)}, nil
	case iana.ProtocolIPv6ICMP:
		return &PacketConn{c: c, p6: ipv6.NewPacketConn(c)}, nil
	default:
		return &PacketConn{c: c}, nil
	}
}

// PacketConns returns a slice containing a net.PacketConn for each matching socket type
// passed to this process.
//
// The order of the file descriptors is preserved in the returned slice.
// Nil values are used to fill any gaps. For example if systemd were to return file descriptors
// corresponding with "udp, tcp, udp", then the slice would contain {net.PacketConn, nil, net.PacketConn}
func PacketConns(unsetEnv bool) ([]net.PacketConn, error) {
	files := Files(unsetEnv)
	conns := make([]net.PacketConn, len(files))

	for i, f := range files {
		if pc, err := net.FilePacketConn(f); err == nil {
			conns[i] = pc
		}
	}
	return conns, nil
}

// PacketConns returns a slice containing a net.PacketConn for each matching socket type
// passed to this process.
//
// The order of the file descriptors is preserved in the returned slice.
// Nil values are used to fill any gaps. For example if systemd were to return file descriptors
// corresponding with "udp, tcp, udp", then the slice would contain {net.PacketConn, nil, net.PacketConn}
func PacketConns(unsetEnv bool) ([]net.PacketConn, error) {
	files := Files(unsetEnv)
	conns := make([]net.PacketConn, 0)
	for i := 0; i < len(files); i++ {
		if pc, err := net.FilePacketConn(files[i]); err == nil {
			conns = append(conns, pc)
			continue
		} else {
			conns = append(conns, nil)
		}
	}
	return conns, nil
}

func main() {
	flag.Parse()
	ip := net.ParseIP(*group)

	s, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
	if err != nil {
		log.Fatal(err)
	}
	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEPORT, 1)
	lsa := syscall.SockaddrInet4{Port: *port}
	copy(lsa.Addr[:], ip.To4())
	if err := syscall.Bind(s, &lsa); err != nil {
		syscall.Close(s)
		log.Fatal(err)
	}
	f := os.NewFile(uintptr(s), "")
	c, err := net.FilePacketConn(f)
	f.Close()
	if err != nil {
		log.Fatal(err)
	}
	p := ipv4.NewPacketConn(c)
	defer p.Close()

	ift, err := net.Interfaces()
	if err != nil {
		log.Fatal(err)
	}
	avail := net.FlagMulticast | net.FlagUp
	for _, ifi := range ift {
		if ifi.Flags&avail != avail {
			continue
		}
		if err := p.JoinGroup(&ifi, &net.UDPAddr{IP: ip}); err != nil {
			log.Println(err, "on", ifi)
		}
	}

	log.Println(c.LocalAddr())
	go receiver(c)

	sig := make(chan os.Signal)
	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
	for {
		select {
		case <-sig:
			os.Exit(0)
		}
	}
}

// NewReusablePortPacketConn returns net.FilePacketConn that created from
// a file discriptor for a socket with SO_REUSEPORT option.
func NewReusablePortPacketConn(proto, addr string) (l net.PacketConn, err error) {
	var (
		soType, fd int
		file       *os.File
		sockaddr   syscall.Sockaddr
	)

	if sockaddr, soType, err = getSockaddr(proto, addr); err != nil {
		return nil, err
	}

	syscall.ForkLock.RLock()
	fd, err = syscall.Socket(soType, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
	if err == nil {
		syscall.CloseOnExec(fd)
	}
	syscall.ForkLock.RUnlock()
	if err != nil {
		syscall.Close(fd)
		return nil, err
	}

	if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
		return nil, err
	}

	if err = syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, reusePort, 1); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	if err = syscall.Bind(fd, sockaddr); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	file = os.NewFile(uintptr(fd), getSocketFileName(proto, addr))
	if l, err = net.FilePacketConn(file); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	if err = file.Close(); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	return l, err
}

func createConn(domain, proto int) net.PacketConn {
	s, err := syscall.Socket(domain, syscall.SOCK_RAW, proto) //int(htons(syscall.ETH_P_ALL))
	if err != nil {
		panic(err)
	}
	f := os.NewFile(uintptr(s), fmt.Sprintf("fd-%d-%d-%d", domain, proto, s))
	// create ne file packet connection
	c, err := net.FilePacketConn(f)
	if err != nil {
		panic(err)
	}
	// FilePacketConn uses copy so we can close these
	syscall.Close(s)
	f.Close()

	return c
}

func udpConn(laddr *net.UDPAddr, ifname string) (net.PacketConn, error) {
	if laddr == nil {
		laddr = &net.UDPAddr{IP: net.IPv4zero, Port: 0}
	}

	s, err1 := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
	if err1 != nil {
		return nil, fmt.Errorf("MulticastListener: could not create socket(laddr=%v,ifname=%s): %v", laddr, ifname, err1)
	}
	if err := syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err != nil {
		syscall.Close(s)
		return nil, fmt.Errorf("MulticastListener: could not set reuse addr socket(laddr=%v,ifname=%s): %v", laddr, ifname, err)
	}
	if ifname != "" {
		if err := syscall.SetsockoptString(s, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, ifname); err != nil {
			syscall.Close(s)
			return nil, fmt.Errorf("MulticastListener: could not bind to device socket(laddr=%v, ifname=%s): %v", laddr, ifname, err)
		}
	}

	lsa := syscall.SockaddrInet4{Port: laddr.Port}
	copy(lsa.Addr[:], laddr.IP.To4())

	if err := syscall.Bind(s, &lsa); err != nil {
		syscall.Close(s)
		return nil, fmt.Errorf("MulticastListener: could not bind socket to address %v: %v", laddr, err)
	}
	f := os.NewFile(uintptr(s), "")
	c, err2 := net.FilePacketConn(f)
	f.Close()
	if err2 != nil {
		syscall.Close(s)
		return nil, fmt.Errorf("MulticastListener: could not get packet connection for socket(laddr=%v,ifname=%s): %v", laddr, ifname, err2)
	}

	return c, nil
}

// see also https://github.com/jbenet/go-reuseport/blob/master/impl_unix.go#L279
func NewSocket(addr *net.UDPAddr, recvBuf int) (net.PacketConn, error) {
	sockFD, err := unix.Socket(unix.AF_INET, unix.SOCK_DGRAM|syscall.SOCK_CLOEXEC|syscall.SOCK_NONBLOCK, 0)
	if err != nil {
		return nil, err
	}

	// unix.SO_REUSEPORT is not defined on linux 386/amd64, see
	// https://github.com/golang/go/issues/16075
	if err := unix.SetsockoptInt(sockFD, unix.SOL_SOCKET, 0xf, 1); err != nil {
		return nil, err
	}
	if err := unix.SetsockoptInt(sockFD, unix.SOL_SOCKET, unix.SO_RCVBUF, recvBuf); err != nil {
		return nil, err
	}

	sockaddr := unix.SockaddrInet4{
		Port: addr.Port,
	}
	if copied := copy(sockaddr.Addr[:], addr.IP); copied != net.IPv4len {
		panic("did not copy enough bytes of ip address")
	}
	if err := unix.Bind(sockFD, &sockaddr); err != nil {
		return nil, err
	}

	osFD := os.NewFile(uintptr(sockFD), "veneursock")
	// this will close the FD we passed to NewFile
	defer osFD.Close()

	// however, FilePacketConn duplicates the FD, so closing the File's FD does
	// not affect this object's FD
	ret, err := net.FilePacketConn(osFD)
	if err != nil {
		return nil, err
	}
	return ret, nil
}

func listenPacket(netw, addr string) (p net.PacketConn, err error) {
	var (
		file *os.File
	)

	fd, err := listen(netw, addr)
	if err != nil {
		return nil, err
	}

	file = os.NewFile(uintptr(fd), filePrefix+strconv.Itoa(os.Getpid()))
	if p, err = net.FilePacketConn(file); err != nil {
		syscall.Close(fd)
		return nil, err
	}

	if err = file.Close(); err != nil {
		syscall.Close(fd)
		p.Close()
		return nil, err
	}

	return p, err
}

// Returns UDP Multicast packet connection to read incoming bytes from
func GetStreamSource(url conf.Url) (net.PacketConn, error) {
	f, err := getSocketFile(url.Source)
	if err != nil {
		return nil, err
	}
	c, err := net.FilePacketConn(f)
	if err != nil {
		log.Printf("Failed to get packet file connection: %s", err)
		return nil, err
	}
	f.Close()
	host, _, err := net.SplitHostPort(url.Source)
	ipAddr := net.ParseIP(host).To4()
	if err != nil {
		log.Printf("Cannot resolve address %s", url.Source)
		return nil, err
	}
	iface, _ := net.InterfaceByName(url.Interface)
	if err := ipv4.NewPacketConn(c).JoinGroup(iface, &net.UDPAddr{IP: net.IPv4(ipAddr[0], ipAddr[1], ipAddr[2], ipAddr[3])}); err != nil {
		log.Printf("Failed to join mulitcast group: %s", err)
		return nil, err
	}
	return c, nil
}

// startServers starts all the servers in groupings,
// taking into account whether or not this process is
// a child from a graceful restart or not. It blocks
// until the servers are listening.
func startServers(groupings bindingGroup) error {
	var startupWg sync.WaitGroup
	errChan := make(chan error, len(groupings)) // must be buffered to allow Serve functions below to return if stopped later

	for _, group := range groupings {
		s, err := server.New(group.BindAddr.String(), group.Configs, GracefulTimeout)
		if err != nil {
			return err
		}
		// TODO(miek): does not work, because this callback uses http instead of dns
		//		s.ReqCallback = https.RequestCallback // ensures we can solve ACME challenges while running
		if s.OnDemandTLS {
			s.TLSConfig.GetCertificate = https.GetOrObtainCertificate // TLS on demand -- awesome!
		} else {
			s.TLSConfig.GetCertificate = https.GetCertificate
		}

		var (
			ln net.Listener
			pc net.PacketConn
		)

		if IsRestart() {
			// Look up this server's listener in the map of inherited file descriptors; if we don't have one, we must make a new one (later).
			if fdIndex, ok := loadedGob.ListenerFds["tcp"+s.Addr]; ok {
				file := os.NewFile(fdIndex, "")

				fln, err := net.FileListener(file)
				if err != nil {
					return err
				}

				ln, ok = fln.(*net.TCPListener)
				if !ok {
					return errors.New("listener for " + s.Addr + " was not a *net.TCPListener")
				}

				file.Close()
				delete(loadedGob.ListenerFds, "tcp"+s.Addr)
			}
			if fdIndex, ok := loadedGob.ListenerFds["udp"+s.Addr]; ok {
				file := os.NewFile(fdIndex, "")

				fpc, err := net.FilePacketConn(file)
				if err != nil {
					return err
				}

				pc, ok = fpc.(*net.UDPConn)
				if !ok {
					return errors.New("packetConn for " + s.Addr + " was not a *net.PacketConn")
				}

				file.Close()
				delete(loadedGob.ListenerFds, "udp"+s.Addr)
			}
		}

		wg.Add(1)
		go func(s *server.Server, ln net.Listener, pc net.PacketConn) {
			defer wg.Done()

			// run startup functions that should only execute when the original parent process is starting.
			if !IsRestart() && !startedBefore {
				err := s.RunFirstStartupFuncs()
				if err != nil {
					errChan <- err
					return
				}
			}

			// start the server
			if ln != nil && pc != nil {
				errChan <- s.Serve(ln, pc)
			} else {
				errChan <- s.ListenAndServe()
			}
		}(s, ln, pc)

		startupWg.Add(1)
		go func(s *server.Server) {
			defer startupWg.Done()
			s.WaitUntilStarted()
		}(s)

		serversMu.Lock()
		servers = append(servers, s)
		serversMu.Unlock()
	}

	// Close the remaining (unused) file descriptors to free up resources
	if IsRestart() {
		for key, fdIndex := range loadedGob.ListenerFds {
			os.NewFile(fdIndex, "").Close()
			delete(loadedGob.ListenerFds, key)
		}
//.........这里部分代码省略.........

func startServers(serverList []Server, inst *Instance, restartFds map[string]restartTriple) error {
	errChan := make(chan error, len(serverList))

	for _, s := range serverList {
		var (
			ln  net.Listener
			pc  net.PacketConn
			err error
		)

		// If this is a reload and s is a GracefulServer,
		// reuse the listener for a graceful restart.
		if gs, ok := s.(GracefulServer); ok && restartFds != nil {
			addr := gs.Address()
			if old, ok := restartFds[addr]; ok {
				// listener
				if old.listener != nil {
					file, err := old.listener.File()
					if err != nil {
						return err
					}
					ln, err = net.FileListener(file)
					if err != nil {
						return err
					}
					file.Close()
				}
				// packetconn
				if old.packet != nil {
					file, err := old.packet.File()
					if err != nil {
						return err
					}
					pc, err = net.FilePacketConn(file)
					if err != nil {
						return err
					}
					file.Close()
				}
			}
		}

		if ln == nil {
			ln, err = s.Listen()
			if err != nil {
				return err
			}
		}
		if pc == nil {
			pc, err = s.ListenPacket()
			if err != nil {
				return err
			}
		}

		inst.wg.Add(2)
		go func(s Server, ln net.Listener, pc net.PacketConn, inst *Instance) {
			defer inst.wg.Done()

			go func() {
				errChan <- s.Serve(ln)
				defer inst.wg.Done()
			}()
			errChan <- s.ServePacket(pc)
		}(s, ln, pc, inst)

		inst.servers = append(inst.servers, ServerListener{server: s, listener: ln, packet: pc})
	}

	// Log errors that may be returned from Serve() calls,
	// these errors should only be occurring in the server loop.
	go func() {
		for err := range errChan {
			if err == nil {
				continue
			}
			if strings.Contains(err.Error(), "use of closed network connection") {
				// this error is normal when closing the listener
				continue
			}
			log.Println(err)
		}
	}()

	return nil
}