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// UDPConn is the implementation of the Conn and PacketConn
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// interfaces for UDP network connections.
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// UDPConn is the implementation of the Conn and PacketConn interfaces
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// for UDP network connections.
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type UDPConn struct {
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// SetDeadline implements the Conn SetDeadline method.
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func (c *UDPConn) SetDeadline(t time.Time) error {
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// SetReadDeadline implements the Conn SetReadDeadline method.
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func (c *UDPConn) SetReadDeadline(t time.Time) error {
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// SetWriteDeadline implements the Conn SetWriteDeadline method.
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func (c *UDPConn) SetWriteDeadline(t time.Time) error {
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// UDP-specific methods.
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func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
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// ReadFromUDP reads a UDP packet from c, copying the payload into b.
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// It returns the number of bytes copied into b and the return address
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// that was on the packet.
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// ReadFromUDP can be made to time out and return an error with Timeout() == true
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// after a fixed time limit; see SetDeadline and SetReadDeadline.
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// ReadFromUDP can be made to time out and return an error with
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// Timeout() == true after a fixed time limit; see SetDeadline and
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func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
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if !c.ok() || c.fd.data == nil {
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return 0, nil, syscall.EINVAL
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c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
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buf := make([]byte, udpHeaderSize+len(b))
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m, err := c.data.Read(buf)
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m, err := c.fd.data.Read(buf)
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h, buf := unmarshalUDPHeader(buf)
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return n, &UDPAddr{h.raddr, int(h.rport)}, nil
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return n, &UDPAddr{IP: h.raddr, Port: int(h.rport)}, nil
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// ReadFrom implements the PacketConn ReadFrom method.
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func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
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func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
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return 0, nil, syscall.EINVAL
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return c.ReadFromUDP(b)
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// WriteToUDP writes a UDP packet to addr via c, copying the payload from b.
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// ReadMsgUDP reads a packet from c, copying the payload into b and
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// the associated out-of-band data into oob. It returns the number
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// of bytes copied into b, the number of bytes copied into oob, the
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// flags that were set on the packet and the source address of the
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func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
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return 0, 0, 0, nil, syscall.EPLAN9
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// WriteToUDP writes a UDP packet to addr via c, copying the payload
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// WriteToUDP can be made to time out and return
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// an error with Timeout() == true after a fixed time limit;
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// see SetDeadline and SetWriteDeadline.
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// On packet-oriented connections, write timeouts are rare.
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func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err error) {
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// WriteToUDP can be made to time out and return an error with
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// Timeout() == true after a fixed time limit; see SetDeadline and
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// SetWriteDeadline. On packet-oriented connections, write timeouts
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func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
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if !c.ok() || c.fd.data == nil {
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return 0, syscall.EINVAL
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c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
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h := new(udpHeader)
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h.raddr = addr.IP.To16()
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h.laddr = c.laddr.(*UDPAddr).IP.To16()
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h.laddr = c.fd.laddr.(*UDPAddr).IP.To16()
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h.ifcaddr = IPv6zero // ignored (receive only)
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h.rport = uint16(addr.Port)
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h.lport = uint16(c.laddr.(*UDPAddr).Port)
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h.lport = uint16(c.fd.laddr.(*UDPAddr).Port)
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buf := make([]byte, udpHeaderSize+len(b))
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i := copy(buf, h.Bytes())
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return c.data.Write(buf)
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return c.fd.data.Write(buf)
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// WriteTo implements the PacketConn WriteTo method.
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func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
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func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
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return 0, syscall.EINVAL
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a, ok := addr.(*UDPAddr)
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return 0, &OpError{"write", c.dir, addr, syscall.EINVAL}
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return 0, &OpError{"write", c.fd.dir, addr, syscall.EINVAL}
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return c.WriteToUDP(b, a)
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// WriteMsgUDP writes a packet to addr via c, copying the payload from
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// b and the associated out-of-band data from oob. It returns the
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// number of payload and out-of-band bytes written.
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func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
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return 0, 0, syscall.EPLAN9
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// DialUDP connects to the remote address raddr on the network net,
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// which must be "udp", "udp4", or "udp6". If laddr is not nil, it is used
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// as the local address for the connection.
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func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err error) {
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// which must be "udp", "udp4", or "udp6". If laddr is not nil, it is
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// used as the local address for the connection.
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func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
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return dialUDP(net, laddr, raddr, noDeadline)
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func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, error) {
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if !deadline.IsZero() {
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panic("net.dialUDP: deadline not implemented on Plan 9")
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case "udp", "udp4", "udp6":
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// ListenUDP listens for incoming UDP packets addressed to the
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// local address laddr. The returned connection c's ReadFrom
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// and WriteTo methods can be used to receive and send UDP
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// packets with per-packet addressing.
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func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err error) {
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// ListenUDP listens for incoming UDP packets addressed to the local
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// address laddr. Net must be "udp", "udp4", or "udp6". If laddr has
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// a port of 0, ListenUDP will choose an available port.
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// The LocalAddr method of the returned UDPConn can be used to
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// discover the port. The returned connection's ReadFrom and WriteTo
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// methods can be used to receive and send UDP packets with per-packet
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func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
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case "udp", "udp4", "udp6":
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return nil, UnknownNetworkError(net)
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if laddr == nil {
177
return nil, &OpError{"listen", net, nil, errMissingAddress}
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l, err := listenPlan9(net, laddr)
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_, err = l.ctl.WriteString("headers")
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return &UDPConn{*l.plan9Conn()}, nil
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l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
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return newUDPConn(l.netFD()), nil
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// ListenMulticastUDP listens for incoming multicast UDP packets
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// addressed to the group address gaddr on ifi, which specifies
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// the interface to join. ListenMulticastUDP uses default
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// multicast interface if ifi is nil.
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// addressed to the group address gaddr on ifi, which specifies the
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// interface to join. ListenMulticastUDP uses default multicast
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// interface if ifi is nil.
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func ListenMulticastUDP(net string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
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return nil, syscall.EPLAN9