libgo/go/net/udpsock.go - gcc - Git at Google

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package net

 import (
 	"context"
 	"internal/itoa"
 	"net/netip"
 	"syscall"
 )

 // BUG(mikio): On Plan 9, the ReadMsgUDP and
 // WriteMsgUDP methods of UDPConn are not implemented.

 // BUG(mikio): On Windows, the File method of UDPConn is not
 // implemented.

 // BUG(mikio): On JS, methods and functions related to UDPConn are not
 // implemented.

 // UDPAddr represents the address of a UDP end point.
 type UDPAddr struct {
 	IP   IP
 	Port int
 	Zone string // IPv6 scoped addressing zone
 }

 // AddrPort returns the UDPAddr a as a netip.AddrPort.
 //
 // If a.Port does not fit in a uint16, it's silently truncated.
 //
 // If a is nil, a zero value is returned.
 func (a *UDPAddr) AddrPort() netip.AddrPort {
 	if a == nil {
 		return netip.AddrPort{}
 	}
 	na, _ := netip.AddrFromSlice(a.IP)
 	na = na.WithZone(a.Zone)
 	return netip.AddrPortFrom(na, uint16(a.Port))
 }

 // Network returns the address's network name, "udp".
 func (a *UDPAddr) Network() string { return "udp" }

 func (a *UDPAddr) String() string {
 	if a == nil {
 		return "<nil>"
 	}
 	ip := ipEmptyString(a.IP)
 	if a.Zone != "" {
 		return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
 	}
 	return JoinHostPort(ip, itoa.Itoa(a.Port))
 }

 func (a *UDPAddr) isWildcard() bool {
 	if a == nil || a.IP == nil {
 		return true
 	}
 	return a.IP.IsUnspecified()
 }

 func (a *UDPAddr) opAddr() Addr {
 	if a == nil {
 		return nil
 	}
 	return a
 }

 // ResolveUDPAddr returns an address of UDP end point.
 //
 // The network must be a UDP network name.
 //
 // If the host in the address parameter is not a literal IP address or
 // the port is not a literal port number, ResolveUDPAddr resolves the
 // address to an address of UDP end point.
 // Otherwise, it parses the address as a pair of literal IP address
 // and port number.
 // The address parameter can use a host name, but this is not
 // recommended, because it will return at most one of the host name's
 // IP addresses.
 //
 // See func Dial for a description of the network and address
 // parameters.
 func ResolveUDPAddr(network, address string) (*UDPAddr, error) {
 	switch network {
 	case "udp", "udp4", "udp6":
 	case "": // a hint wildcard for Go 1.0 undocumented behavior
 		network = "udp"
 	default:
 		return nil, UnknownNetworkError(network)
 	}
 	addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
 	if err != nil {
 		return nil, err
 	}
 	return addrs.forResolve(network, address).(*UDPAddr), nil
 }

 // UDPAddrFromAddrPort returns addr as a UDPAddr. If addr.IsValid() is false,
 // then the returned UDPAddr will contain a nil IP field, indicating an
 // address family-agnostic unspecified address.
 func UDPAddrFromAddrPort(addr netip.AddrPort) *UDPAddr {
 	return &UDPAddr{
 		IP:   addr.Addr().AsSlice(),
 		Zone: addr.Addr().Zone(),
 		Port: int(addr.Port()),
 	}
 }

 // An addrPortUDPAddr is a netip.AddrPort-based UDP address that satisfies the Addr interface.
 type addrPortUDPAddr struct {
 	netip.AddrPort
 }

 func (addrPortUDPAddr) Network() string { return "udp" }

 // UDPConn is the implementation of the Conn and PacketConn interfaces
 // for UDP network connections.
 type UDPConn struct {
 	conn
 }

 // SyscallConn returns a raw network connection.
 // This implements the syscall.Conn interface.
 func (c *UDPConn) SyscallConn() (syscall.RawConn, error) {
 	if !c.ok() {
 		return nil, syscall.EINVAL
 	}
 	return newRawConn(c.fd)
 }

 // ReadFromUDP acts like ReadFrom but returns a UDPAddr.
 func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
 	// This function is designed to allow the caller to control the lifetime
 	// of the returned *UDPAddr and thereby prevent an allocation.
 	// See https://blog.filippo.io/efficient-go-apis-with-the-inliner/.
 	// The real work is done by readFromUDP, below.
 	return c.readFromUDP(b, &UDPAddr{})
 }

 // readFromUDP implements ReadFromUDP.
 func (c *UDPConn) readFromUDP(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
 	if !c.ok() {
 		return 0, nil, syscall.EINVAL
 	}
 	n, addr, err := c.readFrom(b, addr)
 	if err != nil {
 		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 	}
 	return n, addr, err
 }

 // ReadFrom implements the PacketConn ReadFrom method.
 func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
 	n, addr, err := c.readFromUDP(b, &UDPAddr{})
 	if addr == nil {
 		// Return Addr(nil), not Addr(*UDPConn(nil)).
 		return n, nil, err
 	}
 	return n, addr, err
 }

 // ReadFromUDPAddrPort acts like ReadFrom but returns a netip.AddrPort.
 func (c *UDPConn) ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
 	if !c.ok() {
 		return 0, netip.AddrPort{}, syscall.EINVAL
 	}
 	n, addr, err = c.readFromAddrPort(b)
 	if err != nil {
 		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 	}
 	return n, addr, err
 }

 // ReadMsgUDP reads a message from c, copying the payload into b and
 // the associated out-of-band data into oob. It returns the number of
 // bytes copied into b, the number of bytes copied into oob, the flags
 // that were set on the message and the source address of the message.
 //
 // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
 // used to manipulate IP-level socket options in oob.
 func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
 	var ap netip.AddrPort
 	n, oobn, flags, ap, err = c.ReadMsgUDPAddrPort(b, oob)
 	if ap.IsValid() {
 		addr = UDPAddrFromAddrPort(ap)
 	}
 	return
 }

 // ReadMsgUDPAddrPort is like ReadMsgUDP but returns an netip.AddrPort instead of a UDPAddr.
 func (c *UDPConn) ReadMsgUDPAddrPort(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
 	if !c.ok() {
 		return 0, 0, 0, netip.AddrPort{}, syscall.EINVAL
 	}
 	n, oobn, flags, addr, err = c.readMsg(b, oob)
 	if err != nil {
 		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 	}
 	return
 }

 // WriteToUDP acts like WriteTo but takes a UDPAddr.
 func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
 	if !c.ok() {
 		return 0, syscall.EINVAL
 	}
 	n, err := c.writeTo(b, addr)
 	if err != nil {
 		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
 	}
 	return n, err
 }

 // WriteToUDPAddrPort acts like WriteTo but takes a netip.AddrPort.
 func (c *UDPConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) {
 	if !c.ok() {
 		return 0, syscall.EINVAL
 	}
 	n, err := c.writeToAddrPort(b, addr)
 	if err != nil {
 		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
 	}
 	return n, err
 }

 // WriteTo implements the PacketConn WriteTo method.
 func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
 	if !c.ok() {
 		return 0, syscall.EINVAL
 	}
 	a, ok := addr.(*UDPAddr)
 	if !ok {
 		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
 	}
 	n, err := c.writeTo(b, a)
 	if err != nil {
 		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
 	}
 	return n, err
 }

 // WriteMsgUDP writes a message to addr via c if c isn't connected, or
 // to c's remote address if c is connected (in which case addr must be
 // nil). The payload is copied from b and the associated out-of-band
 // data is copied from oob. It returns the number of payload and
 // out-of-band bytes written.
 //
 // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
 // used to manipulate IP-level socket options in oob.
 func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
 	if !c.ok() {
 		return 0, 0, syscall.EINVAL
 	}
 	n, oobn, err = c.writeMsg(b, oob, addr)
 	if err != nil {
 		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
 	}
 	return
 }

 // WriteMsgUDPAddrPort is like WriteMsgUDP but takes a netip.AddrPort instead of a UDPAddr.
 func (c *UDPConn) WriteMsgUDPAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn int, err error) {
 	if !c.ok() {
 		return 0, 0, syscall.EINVAL
 	}
 	n, oobn, err = c.writeMsgAddrPort(b, oob, addr)
 	if err != nil {
 		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
 	}
 	return
 }

 func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }

 // DialUDP acts like Dial for UDP networks.
 //
 // The network must be a UDP network name; see func Dial for details.
 //
 // If laddr is nil, a local address is automatically chosen.
 // If the IP field of raddr is nil or an unspecified IP address, the
 // local system is assumed.
 func DialUDP(network string, laddr, raddr *UDPAddr) (*UDPConn, error) {
 	switch network {
 	case "udp", "udp4", "udp6":
 	default:
 		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
 	}
 	if raddr == nil {
 		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
 	}
 	sd := &sysDialer{network: network, address: raddr.String()}
 	c, err := sd.dialUDP(context.Background(), laddr, raddr)
 	if err != nil {
 		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
 	}
 	return c, nil
 }

 // ListenUDP acts like ListenPacket for UDP networks.
 //
 // The network must be a UDP network name; see func Dial for details.
 //
 // If the IP field of laddr is nil or an unspecified IP address,
 // ListenUDP listens on all available IP addresses of the local system
 // except multicast IP addresses.
 // If the Port field of laddr is 0, a port number is automatically
 // chosen.
 func ListenUDP(network string, laddr *UDPAddr) (*UDPConn, error) {
 	switch network {
 	case "udp", "udp4", "udp6":
 	default:
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
 	}
 	if laddr == nil {
 		laddr = &UDPAddr{}
 	}
 	sl := &sysListener{network: network, address: laddr.String()}
 	c, err := sl.listenUDP(context.Background(), laddr)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
 	}
 	return c, nil
 }

 // ListenMulticastUDP acts like ListenPacket for UDP networks but
 // takes a group address on a specific network interface.
 //
 // The network must be a UDP network name; see func Dial for details.
 //
 // ListenMulticastUDP listens on all available IP addresses of the
 // local system including the group, multicast IP address.
 // If ifi is nil, ListenMulticastUDP uses the system-assigned
 // multicast interface, although this is not recommended because the
 // assignment depends on platforms and sometimes it might require
 // routing configuration.
 // If the Port field of gaddr is 0, a port number is automatically
 // chosen.
 //
 // ListenMulticastUDP is just for convenience of simple, small
 // applications. There are golang.org/x/net/ipv4 and
 // golang.org/x/net/ipv6 packages for general purpose uses.
 //
 // Note that ListenMulticastUDP will set the IP_MULTICAST_LOOP socket option
 // to 0 under IPPROTO_IP, to disable loopback of multicast packets.
 func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
 	switch network {
 	case "udp", "udp4", "udp6":
 	default:
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
 	}
 	if gaddr == nil || gaddr.IP == nil {
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
 	}
 	sl := &sysListener{network: network, address: gaddr.String()}
 	c, err := sl.listenMulticastUDP(context.Background(), ifi, gaddr)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
 	}
 	return c, nil
 }
	// Copyright 2009 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package net

	import (
	"context"
	"internal/itoa"
	"net/netip"
	"syscall"
	)

	// BUG(mikio): On Plan 9, the ReadMsgUDP and
	// WriteMsgUDP methods of UDPConn are not implemented.

	// BUG(mikio): On Windows, the File method of UDPConn is not
	// implemented.

	// BUG(mikio): On JS, methods and functions related to UDPConn are not
	// implemented.

	// UDPAddr represents the address of a UDP end point.
	type UDPAddr struct {
	IP IP
	Port int
	Zone string // IPv6 scoped addressing zone
	}

	// AddrPort returns the UDPAddr a as a netip.AddrPort.
	//
	// If a.Port does not fit in a uint16, it's silently truncated.
	//
	// If a is nil, a zero value is returned.
	func (a *UDPAddr) AddrPort() netip.AddrPort {
	if a == nil {
	return netip.AddrPort{}
	}
	na, _ := netip.AddrFromSlice(a.IP)
	na = na.WithZone(a.Zone)
	return netip.AddrPortFrom(na, uint16(a.Port))
	}

	// Network returns the address's network name, "udp".
	func (a *UDPAddr) Network() string { return "udp" }

	func (a *UDPAddr) String() string {
	if a == nil {
	return "<nil>"
	}
	ip := ipEmptyString(a.IP)
	if a.Zone != "" {
	return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
	}
	return JoinHostPort(ip, itoa.Itoa(a.Port))
	}

	func (a *UDPAddr) isWildcard() bool {
	if a == nil \|\| a.IP == nil {
	return true
	}
	return a.IP.IsUnspecified()
	}

	func (a *UDPAddr) opAddr() Addr {
	if a == nil {
	return nil
	}
	return a
	}

	// ResolveUDPAddr returns an address of UDP end point.
	//
	// The network must be a UDP network name.
	//
	// If the host in the address parameter is not a literal IP address or
	// the port is not a literal port number, ResolveUDPAddr resolves the
	// address to an address of UDP end point.
	// Otherwise, it parses the address as a pair of literal IP address
	// and port number.
	// The address parameter can use a host name, but this is not
	// recommended, because it will return at most one of the host name's
	// IP addresses.
	//
	// See func Dial for a description of the network and address
	// parameters.
	func ResolveUDPAddr(network, address string) (*UDPAddr, error) {
	switch network {
	case "udp", "udp4", "udp6":
	case "": // a hint wildcard for Go 1.0 undocumented behavior
	network = "udp"
	default:
	return nil, UnknownNetworkError(network)
	}
	addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
	if err != nil {
	return nil, err
	}
	return addrs.forResolve(network, address).(*UDPAddr), nil
	}

	// UDPAddrFromAddrPort returns addr as a UDPAddr. If addr.IsValid() is false,
	// then the returned UDPAddr will contain a nil IP field, indicating an
	// address family-agnostic unspecified address.
	func UDPAddrFromAddrPort(addr netip.AddrPort) *UDPAddr {
	return &UDPAddr{
	IP: addr.Addr().AsSlice(),
	Zone: addr.Addr().Zone(),
	Port: int(addr.Port()),
	}
	}

	// An addrPortUDPAddr is a netip.AddrPort-based UDP address that satisfies the Addr interface.
	type addrPortUDPAddr struct {
	netip.AddrPort
	}

	func (addrPortUDPAddr) Network() string { return "udp" }

	// UDPConn is the implementation of the Conn and PacketConn interfaces
	// for UDP network connections.
	type UDPConn struct {
	conn
	}

	// SyscallConn returns a raw network connection.
	// This implements the syscall.Conn interface.
	func (c *UDPConn) SyscallConn() (syscall.RawConn, error) {
	if !c.ok() {
	return nil, syscall.EINVAL
	}
	return newRawConn(c.fd)
	}

	// ReadFromUDP acts like ReadFrom but returns a UDPAddr.
	func (c UDPConn) ReadFromUDP(b []byte) (n int, addr UDPAddr, err error) {
	// This function is designed to allow the caller to control the lifetime
	// of the returned *UDPAddr and thereby prevent an allocation.
	// See https://blog.filippo.io/efficient-go-apis-with-the-inliner/.
	// The real work is done by readFromUDP, below.
	return c.readFromUDP(b, &UDPAddr{})
	}

	// readFromUDP implements ReadFromUDP.
	func (c UDPConn) readFromUDP(b []byte, addr UDPAddr) (int, *UDPAddr, error) {
	if !c.ok() {
	return 0, nil, syscall.EINVAL
	}
	n, addr, err := c.readFrom(b, addr)
	if err != nil {
	err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, addr, err
	}

	// ReadFrom implements the PacketConn ReadFrom method.
	func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
	n, addr, err := c.readFromUDP(b, &UDPAddr{})
	if addr == nil {
	// Return Addr(nil), not Addr(*UDPConn(nil)).
	return n, nil, err
	}
	return n, addr, err
	}

	// ReadFromUDPAddrPort acts like ReadFrom but returns a netip.AddrPort.
	func (c *UDPConn) ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
	if !c.ok() {
	return 0, netip.AddrPort{}, syscall.EINVAL
	}
	n, addr, err = c.readFromAddrPort(b)
	if err != nil {
	err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, addr, err
	}

	// ReadMsgUDP reads a message from c, copying the payload into b and
	// the associated out-of-band data into oob. It returns the number of
	// bytes copied into b, the number of bytes copied into oob, the flags
	// that were set on the message and the source address of the message.
	//
	// The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
	// used to manipulate IP-level socket options in oob.
	func (c UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr UDPAddr, err error) {
	var ap netip.AddrPort
	n, oobn, flags, ap, err = c.ReadMsgUDPAddrPort(b, oob)
	if ap.IsValid() {
	addr = UDPAddrFromAddrPort(ap)
	}
	return
	}

	// ReadMsgUDPAddrPort is like ReadMsgUDP but returns an netip.AddrPort instead of a UDPAddr.
	func (c *UDPConn) ReadMsgUDPAddrPort(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
	if !c.ok() {
	return 0, 0, 0, netip.AddrPort{}, syscall.EINVAL
	}
	n, oobn, flags, addr, err = c.readMsg(b, oob)
	if err != nil {
	err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return
	}

	// WriteToUDP acts like WriteTo but takes a UDPAddr.
	func (c UDPConn) WriteToUDP(b []byte, addr UDPAddr) (int, error) {
	if !c.ok() {
	return 0, syscall.EINVAL
	}
	n, err := c.writeTo(b, addr)
	if err != nil {
	err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	}
	return n, err
	}

	// WriteToUDPAddrPort acts like WriteTo but takes a netip.AddrPort.
	func (c *UDPConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) {
	if !c.ok() {
	return 0, syscall.EINVAL
	}
	n, err := c.writeToAddrPort(b, addr)
	if err != nil {
	err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
	}
	return n, err
	}

	// WriteTo implements the PacketConn WriteTo method.
	func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
	if !c.ok() {
	return 0, syscall.EINVAL
	}
	a, ok := addr.(*UDPAddr)
	if !ok {
	return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
	}
	n, err := c.writeTo(b, a)
	if err != nil {
	err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
	}
	return n, err
	}

	// WriteMsgUDP writes a message to addr via c if c isn't connected, or
	// to c's remote address if c is connected (in which case addr must be
	// nil). The payload is copied from b and the associated out-of-band
	// data is copied from oob. It returns the number of payload and
	// out-of-band bytes written.
	//
	// The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
	// used to manipulate IP-level socket options in oob.
	func (c UDPConn) WriteMsgUDP(b, oob []byte, addr UDPAddr) (n, oobn int, err error) {
	if !c.ok() {
	return 0, 0, syscall.EINVAL
	}
	n, oobn, err = c.writeMsg(b, oob, addr)
	if err != nil {
	err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	}
	return
	}

	// WriteMsgUDPAddrPort is like WriteMsgUDP but takes a netip.AddrPort instead of a UDPAddr.
	func (c *UDPConn) WriteMsgUDPAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn int, err error) {
	if !c.ok() {
	return 0, 0, syscall.EINVAL
	}
	n, oobn, err = c.writeMsgAddrPort(b, oob, addr)
	if err != nil {
	err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
	}
	return
	}

	func newUDPConn(fd netFD) UDPConn { return &UDPConn{conn{fd}} }

	// DialUDP acts like Dial for UDP networks.
	//
	// The network must be a UDP network name; see func Dial for details.
	//
	// If laddr is nil, a local address is automatically chosen.
	// If the IP field of raddr is nil or an unspecified IP address, the
	// local system is assumed.
	func DialUDP(network string, laddr, raddr UDPAddr) (UDPConn, error) {
	switch network {
	case "udp", "udp4", "udp6":
	default:
	return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	if raddr == nil {
	return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
	}
	sd := &sysDialer{network: network, address: raddr.String()}
	c, err := sd.dialUDP(context.Background(), laddr, raddr)
	if err != nil {
	return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
	}
	return c, nil
	}

	// ListenUDP acts like ListenPacket for UDP networks.
	//
	// The network must be a UDP network name; see func Dial for details.
	//
	// If the IP field of laddr is nil or an unspecified IP address,
	// ListenUDP listens on all available IP addresses of the local system
	// except multicast IP addresses.
	// If the Port field of laddr is 0, a port number is automatically
	// chosen.
	func ListenUDP(network string, laddr UDPAddr) (UDPConn, error) {
	switch network {
	case "udp", "udp4", "udp6":
	default:
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	if laddr == nil {
	laddr = &UDPAddr{}
	}
	sl := &sysListener{network: network, address: laddr.String()}
	c, err := sl.listenUDP(context.Background(), laddr)
	if err != nil {
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
	}
	return c, nil
	}

	// ListenMulticastUDP acts like ListenPacket for UDP networks but
	// takes a group address on a specific network interface.
	//
	// The network must be a UDP network name; see func Dial for details.
	//
	// ListenMulticastUDP listens on all available IP addresses of the
	// local system including the group, multicast IP address.
	// If ifi is nil, ListenMulticastUDP uses the system-assigned
	// multicast interface, although this is not recommended because the
	// assignment depends on platforms and sometimes it might require
	// routing configuration.
	// If the Port field of gaddr is 0, a port number is automatically
	// chosen.
	//
	// ListenMulticastUDP is just for convenience of simple, small
	// applications. There are golang.org/x/net/ipv4 and
	// golang.org/x/net/ipv6 packages for general purpose uses.
	//
	// Note that ListenMulticastUDP will set the IP_MULTICAST_LOOP socket option
	// to 0 under IPPROTO_IP, to disable loopback of multicast packets.
	func ListenMulticastUDP(network string, ifi Interface, gaddr UDPAddr) (*UDPConn, error) {
	switch network {
	case "udp", "udp4", "udp6":
	default:
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
	}
	if gaddr == nil \|\| gaddr.IP == nil {
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
	}
	sl := &sysListener{network: network, address: gaddr.String()}
	c, err := sl.listenMulticastUDP(context.Background(), ifi, gaddr)
	if err != nil {
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
	}
	return c, nil
	}