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// 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
}
// 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
}