src/net/udpsock.go - go - 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"
 	"syscall"
 )

 // BUG(mikio): On NaCl, Plan 9 and Windows, 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 NaCl, the ListenMulticastUDP function is not
 // implemented.

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

 // 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(a.Port))
 	}
 	return JoinHostPort(ip, 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 parses addr as a UDP address of the form "host:port"
 // or "[ipv6-host%zone]:port" and resolves a pair of domain name and
 // port name on the network net, which must be "udp", "udp4" or
 // "udp6".  A literal address or host name for IPv6 must be enclosed
 // in square brackets, as in "[::1]:80", "[ipv6-host]:http" or
 // "[ipv6-host%zone]:80".
 //
 // Resolving a hostname is not recommended because this returns at most
 // one of its IP addresses.
 func ResolveUDPAddr(net, addr string) (*UDPAddr, error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	case "": // a hint wildcard for Go 1.0 undocumented behavior
 		net = "udp"
 	default:
 		return nil, UnknownNetworkError(net)
 	}
 	addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr)
 	if err != nil {
 		return nil, err
 	}
 	return addrs.first(isIPv4).(*UDPAddr), nil
 }

 // 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 reads a UDP packet from c, copying the payload into b.
 // It returns the number of bytes copied into b and the return address
 // that was on the packet.
 //
 // ReadFromUDP can be made to time out and return an error with
 // Timeout() == true after a fixed time limit; see SetDeadline and
 // SetReadDeadline.
 func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
 	if !c.ok() {
 		return 0, nil, syscall.EINVAL
 	}
 	n, addr, err := c.readFrom(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
 }

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

 // ReadMsgUDP reads a packet 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 packet and the source address of the
 // packet.
 func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
 	if !c.ok() {
 		return 0, 0, 0, nil, 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 writes a UDP packet to addr via c, copying the payload
 // from b.
 //
 // WriteToUDP can be made to time out and return an error with
 // Timeout() == true after a fixed time limit; see SetDeadline and
 // SetWriteDeadline. On packet-oriented connections, write timeouts
 // are rare.
 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
 }

 // 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 packet to addr via c if c isn't connected, or
 // to c's remote destination 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.
 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
 }

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

 // DialUDP connects to the remote address raddr on the network net,
 // which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
 // used as the local address for the connection.
 func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
 		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
 	}
 	if raddr == nil {
 		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
 	}
 	c, err := dialUDP(context.Background(), net, laddr, raddr)
 	if err != nil {
 		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
 	}
 	return c, nil
 }

 // ListenUDP listens for incoming UDP packets addressed to the local
 // address laddr. Net must be "udp", "udp4", or "udp6".  If laddr has
 // a port of 0, ListenUDP will choose an available port.
 // The LocalAddr method of the returned UDPConn can be used to
 // discover the port. The returned connection's ReadFrom and WriteTo
 // methods can be used to receive and send UDP packets with per-packet
 // addressing.
 func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
 	}
 	if laddr == nil {
 		laddr = &UDPAddr{}
 	}
 	c, err := listenUDP(context.Background(), net, laddr)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
 	}
 	return c, nil
 }

 // ListenMulticastUDP listens for incoming multicast UDP packets
 // addressed to the group address gaddr on the interface ifi.
 // Network must be "udp", "udp4" or "udp6".
 // ListenMulticastUDP uses the system-assigned multicast interface
 // when ifi is nil, although this is not recommended because the
 // assignment depends on platforms and sometimes it might require
 // routing configuration.
 //
 // 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.
 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}
 	}
 	c, err := listenMulticastUDP(context.Background(), network, 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"
	"syscall"
	)

	// BUG(mikio): On NaCl, Plan 9 and Windows, 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 NaCl, the ListenMulticastUDP function is not
	// implemented.

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

	// 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(a.Port))
	}
	return JoinHostPort(ip, 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 parses addr as a UDP address of the form "host:port"
	// or "[ipv6-host%zone]:port" and resolves a pair of domain name and
	// port name on the network net, which must be "udp", "udp4" or
	// "udp6". A literal address or host name for IPv6 must be enclosed
	// in square brackets, as in "[::1]:80", "[ipv6-host]:http" or
	// "[ipv6-host%zone]:80".
	//
	// Resolving a hostname is not recommended because this returns at most
	// one of its IP addresses.
	func ResolveUDPAddr(net, addr string) (*UDPAddr, error) {
	switch net {
	case "udp", "udp4", "udp6":
	case "": // a hint wildcard for Go 1.0 undocumented behavior
	net = "udp"
	default:
	return nil, UnknownNetworkError(net)
	}
	addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr)
	if err != nil {
	return nil, err
	}
	return addrs.first(isIPv4).(*UDPAddr), nil
	}

	// 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 reads a UDP packet from c, copying the payload into b.
	// It returns the number of bytes copied into b and the return address
	// that was on the packet.
	//
	// ReadFromUDP can be made to time out and return an error with
	// Timeout() == true after a fixed time limit; see SetDeadline and
	// SetReadDeadline.
	func (c UDPConn) ReadFromUDP(b []byte) (int, UDPAddr, error) {
	if !c.ok() {
	return 0, nil, syscall.EINVAL
	}
	n, addr, err := c.readFrom(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
	}

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

	// ReadMsgUDP reads a packet 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 packet and the source address of the
	// packet.
	func (c UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr UDPAddr, err error) {
	if !c.ok() {
	return 0, 0, 0, nil, 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 writes a UDP packet to addr via c, copying the payload
	// from b.
	//
	// WriteToUDP can be made to time out and return an error with
	// Timeout() == true after a fixed time limit; see SetDeadline and
	// SetWriteDeadline. On packet-oriented connections, write timeouts
	// are rare.
	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
	}

	// 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 packet to addr via c if c isn't connected, or
	// to c's remote destination 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.
	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
	}

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

	// DialUDP connects to the remote address raddr on the network net,
	// which must be "udp", "udp4", or "udp6". If laddr is not nil, it is
	// used as the local address for the connection.
	func DialUDP(net string, laddr, raddr UDPAddr) (UDPConn, error) {
	switch net {
	case "udp", "udp4", "udp6":
	default:
	return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
	}
	if raddr == nil {
	return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
	}
	c, err := dialUDP(context.Background(), net, laddr, raddr)
	if err != nil {
	return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
	}
	return c, nil
	}

	// ListenUDP listens for incoming UDP packets addressed to the local
	// address laddr. Net must be "udp", "udp4", or "udp6". If laddr has
	// a port of 0, ListenUDP will choose an available port.
	// The LocalAddr method of the returned UDPConn can be used to
	// discover the port. The returned connection's ReadFrom and WriteTo
	// methods can be used to receive and send UDP packets with per-packet
	// addressing.
	func ListenUDP(net string, laddr UDPAddr) (UDPConn, error) {
	switch net {
	case "udp", "udp4", "udp6":
	default:
	return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
	}
	if laddr == nil {
	laddr = &UDPAddr{}
	}
	c, err := listenUDP(context.Background(), net, laddr)
	if err != nil {
	return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
	}
	return c, nil
	}

	// ListenMulticastUDP listens for incoming multicast UDP packets
	// addressed to the group address gaddr on the interface ifi.
	// Network must be "udp", "udp4" or "udp6".
	// ListenMulticastUDP uses the system-assigned multicast interface
	// when ifi is nil, although this is not recommended because the
	// assignment depends on platforms and sometimes it might require
	// routing configuration.
	//
	// 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.
	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}
	}
	c, err := listenMulticastUDP(context.Background(), network, ifi, gaddr)
	if err != nil {
	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
	}
	return c, nil
	}