libgo/go/net/udpsock.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package net
   6
   7 import (
   8         "context"
   9         "syscall"
  10 )
  11
  12 // BUG(mikio): On NaCl, Plan 9 and Windows, the ReadMsgUDP and
  13 // WriteMsgUDP methods of UDPConn are not implemented.
  14
  15 // BUG(mikio): On Windows, the File method of UDPConn is not
  16 // implemented.
  17
  18 // BUG(mikio): On NaCl, the ListenMulticastUDP function is not
  19 // implemented.
  20
  21 // UDPAddr represents the address of a UDP end point.
  22 type UDPAddr struct {
  23         IP   IP
  24         Port int
  25         Zone string // IPv6 scoped addressing zone
  26 }
  27
  28 // Network returns the address's network name, "udp".
  29 func (a *UDPAddr) Network() string { return "udp" }
  30
  31 func (a *UDPAddr) String() string {
  32         if a == nil {
  33                 return "<nil>"
  34         }
  35         ip := ipEmptyString(a.IP)
  36         if a.Zone != "" {
  37                 return JoinHostPort(ip+"%"+a.Zone, itoa(a.Port))
  38         }
  39         return JoinHostPort(ip, itoa(a.Port))
  40 }
  41
  42 func (a *UDPAddr) isWildcard() bool {
  43         if a == nil || a.IP == nil {
  44                 return true
  45         }
  46         return a.IP.IsUnspecified()
  47 }
  48
  49 func (a *UDPAddr) opAddr() Addr {
  50         if a == nil {
  51                 return nil
  52         }
  53         return a
  54 }
  55
  56 // ResolveUDPAddr parses addr as a UDP address of the form "host:port"
  57 // or "[ipv6-host%zone]:port" and resolves a pair of domain name and
  58 // port name on the network net, which must be "udp", "udp4" or
  59 // "udp6".  A literal address or host name for IPv6 must be enclosed
  60 // in square brackets, as in "[::1]:80", "[ipv6-host]:http" or
  61 // "[ipv6-host%zone]:80".
  62 //
  63 // Resolving a hostname is not recommended because this returns at most
  64 // one of its IP addresses.
  65 func ResolveUDPAddr(net, addr string) (*UDPAddr, error) {
  66         switch net {
  67         case "udp", "udp4", "udp6":
  68         case "": // a hint wildcard for Go 1.0 undocumented behavior
  69                 net = "udp"
  70         default:
  71                 return nil, UnknownNetworkError(net)
  72         }
  73         addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr)
  74         if err != nil {
  75                 return nil, err
  76         }
  77         return addrs.first(isIPv4).(*UDPAddr), nil
  78 }
  79
  80 // UDPConn is the implementation of the Conn and PacketConn interfaces
  81 // for UDP network connections.
  82 type UDPConn struct {
  83         conn
  84 }
  85
  86 // ReadFromUDP reads a UDP packet from c, copying the payload into b.
  87 // It returns the number of bytes copied into b and the return address
  88 // that was on the packet.
  89 //
  90 // ReadFromUDP can be made to time out and return an error with
  91 // Timeout() == true after a fixed time limit; see SetDeadline and
  92 // SetReadDeadline.
  93 func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
  94         if !c.ok() {
  95                 return 0, nil, syscall.EINVAL
  96         }
  97         n, addr, err := c.readFrom(b)
  98         if err != nil {
  99                 err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 100         }
 101         return n, addr, err
 102 }
 103
 104 // ReadFrom implements the PacketConn ReadFrom method.
 105 func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
 106         if !c.ok() {
 107                 return 0, nil, syscall.EINVAL
 108         }
 109         n, addr, err := c.readFrom(b)
 110         if err != nil {
 111                 err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 112         }
 113         if addr == nil {
 114                 return n, nil, err
 115         }
 116         return n, addr, err
 117 }
 118
 119 // ReadMsgUDP reads a packet from c, copying the payload into b and
 120 // the associated out-of-band data into oob. It returns the number
 121 // of bytes copied into b, the number of bytes copied into oob, the
 122 // flags that were set on the packet and the source address of the
 123 // packet.
 124 func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
 125         if !c.ok() {
 126                 return 0, 0, 0, nil, syscall.EINVAL
 127         }
 128         n, oobn, flags, addr, err = c.readMsg(b, oob)
 129         if err != nil {
 130                 err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
 131         }
 132         return
 133 }
 134
 135 // WriteToUDP writes a UDP packet to addr via c, copying the payload
 136 // from b.
 137 //
 138 // WriteToUDP can be made to time out and return an error with
 139 // Timeout() == true after a fixed time limit; see SetDeadline and
 140 // SetWriteDeadline. On packet-oriented connections, write timeouts
 141 // are rare.
 142 func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
 143         if !c.ok() {
 144                 return 0, syscall.EINVAL
 145         }
 146         n, err := c.writeTo(b, addr)
 147         if err != nil {
 148                 err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
 149         }
 150         return n, err
 151 }
 152
 153 // WriteTo implements the PacketConn WriteTo method.
 154 func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
 155         if !c.ok() {
 156                 return 0, syscall.EINVAL
 157         }
 158         a, ok := addr.(*UDPAddr)
 159         if !ok {
 160                 return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
 161         }
 162         n, err := c.writeTo(b, a)
 163         if err != nil {
 164                 err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
 165         }
 166         return n, err
 167 }
 168
 169 // WriteMsgUDP writes a packet to addr via c if c isn't connected, or
 170 // to c's remote destination address if c is connected (in which case
 171 // addr must be nil).  The payload is copied from b and the associated
 172 // out-of-band data is copied from oob. It returns the number of
 173 // payload and out-of-band bytes written.
 174 func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
 175         if !c.ok() {
 176                 return 0, 0, syscall.EINVAL
 177         }
 178         n, oobn, err = c.writeMsg(b, oob, addr)
 179         if err != nil {
 180                 err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
 181         }
 182         return
 183 }
 184
 185 func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
 186
 187 // DialUDP connects to the remote address raddr on the network net,
 188 // which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
 189 // used as the local address for the connection.
 190 func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
 191         switch net {
 192         case "udp", "udp4", "udp6":
 193         default:
 194                 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
 195         }
 196         if raddr == nil {
 197                 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
 198         }
 199         c, err := dialUDP(context.Background(), net, laddr, raddr)
 200         if err != nil {
 201                 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
 202         }
 203         return c, nil
 204 }
 205
 206 // ListenUDP listens for incoming UDP packets addressed to the local
 207 // address laddr. Net must be "udp", "udp4", or "udp6".  If laddr has
 208 // a port of 0, ListenUDP will choose an available port.
 209 // The LocalAddr method of the returned UDPConn can be used to
 210 // discover the port. The returned connection's ReadFrom and WriteTo
 211 // methods can be used to receive and send UDP packets with per-packet
 212 // addressing.
 213 func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
 214         switch net {
 215         case "udp", "udp4", "udp6":
 216         default:
 217                 return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
 218         }
 219         if laddr == nil {
 220                 laddr = &UDPAddr{}
 221         }
 222         c, err := listenUDP(context.Background(), net, laddr)
 223         if err != nil {
 224                 return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
 225         }
 226         return c, nil
 227 }
 228
 229 // ListenMulticastUDP listens for incoming multicast UDP packets
 230 // addressed to the group address gaddr on the interface ifi.
 231 // Network must be "udp", "udp4" or "udp6".
 232 // ListenMulticastUDP uses the system-assigned multicast interface
 233 // when ifi is nil, although this is not recommended because the
 234 // assignment depends on platforms and sometimes it might require
 235 // routing configuration.
 236 //
 237 // ListenMulticastUDP is just for convenience of simple, small
 238 // applications. There are golang.org/x/net/ipv4 and
 239 // golang.org/x/net/ipv6 packages for general purpose uses.
 240 func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
 241         switch network {
 242         case "udp", "udp4", "udp6":
 243         default:
 244                 return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
 245         }
 246         if gaddr == nil || gaddr.IP == nil {
 247                 return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
 248         }
 249         c, err := listenMulticastUDP(context.Background(), network, ifi, gaddr)
 250         if err != nil {
 251                 return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
 252         }
 253         return c, nil
 254 }