udpsock.go

Documentation: net

		 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  	"internal/itoa"
		10  	"syscall"
		11  )
		12  
		13  // BUG(mikio): On Plan 9, the ReadMsgUDP and
		14  // WriteMsgUDP methods of UDPConn are not implemented.
		15  
		16  // BUG(mikio): On Windows, the File method of UDPConn is not
		17  // implemented.
		18  
		19  // BUG(mikio): On JS, methods and functions related to UDPConn are not
		20  // implemented.
		21  
		22  // UDPAddr represents the address of a UDP end point.
		23  type UDPAddr struct {
		24  	IP	 IP
		25  	Port int
		26  	Zone string // IPv6 scoped addressing zone
		27  }
		28  
		29  // Network returns the address's network name, "udp".
		30  func (a *UDPAddr) Network() string { return "udp" }
		31  
		32  func (a *UDPAddr) String() string {
		33  	if a == nil {
		34  		return "<nil>"
		35  	}
		36  	ip := ipEmptyString(a.IP)
		37  	if a.Zone != "" {
		38  		return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
		39  	}
		40  	return JoinHostPort(ip, itoa.Itoa(a.Port))
		41  }
		42  
		43  func (a *UDPAddr) isWildcard() bool {
		44  	if a == nil || a.IP == nil {
		45  		return true
		46  	}
		47  	return a.IP.IsUnspecified()
		48  }
		49  
		50  func (a *UDPAddr) opAddr() Addr {
		51  	if a == nil {
		52  		return nil
		53  	}
		54  	return a
		55  }
		56  
		57  // ResolveUDPAddr returns an address of UDP end point.
		58  //
		59  // The network must be a UDP network name.
		60  //
		61  // If the host in the address parameter is not a literal IP address or
		62  // the port is not a literal port number, ResolveUDPAddr resolves the
		63  // address to an address of UDP end point.
		64  // Otherwise, it parses the address as a pair of literal IP address
		65  // and port number.
		66  // The address parameter can use a host name, but this is not
		67  // recommended, because it will return at most one of the host name's
		68  // IP addresses.
		69  //
		70  // See func Dial for a description of the network and address
		71  // parameters.
		72  func ResolveUDPAddr(network, address string) (*UDPAddr, error) {
		73  	switch network {
		74  	case "udp", "udp4", "udp6":
		75  	case "": // a hint wildcard for Go 1.0 undocumented behavior
		76  		network = "udp"
		77  	default:
		78  		return nil, UnknownNetworkError(network)
		79  	}
		80  	addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
		81  	if err != nil {
		82  		return nil, err
		83  	}
		84  	return addrs.forResolve(network, address).(*UDPAddr), nil
		85  }
		86  
		87  // UDPConn is the implementation of the Conn and PacketConn interfaces
		88  // for UDP network connections.
		89  type UDPConn struct {
		90  	conn
		91  }
		92  
		93  // SyscallConn returns a raw network connection.
		94  // This implements the syscall.Conn interface.
		95  func (c *UDPConn) SyscallConn() (syscall.RawConn, error) {
		96  	if !c.ok() {
		97  		return nil, syscall.EINVAL
		98  	}
		99  	return newRawConn(c.fd)
	 100  }
	 101  
	 102  // ReadFromUDP acts like ReadFrom but returns a UDPAddr.
	 103  func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
	 104  	// This function is designed to allow the caller to control the lifetime
	 105  	// of the returned *UDPAddr and thereby prevent an allocation.
	 106  	// See https://blog.filippo.io/efficient-go-apis-with-the-inliner/.
	 107  	// The real work is done by readFromUDP, below.
	 108  	return c.readFromUDP(b, &UDPAddr{})
	 109  }
	 110  
	 111  // readFromUDP implements ReadFromUDP.
	 112  func (c *UDPConn) readFromUDP(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
	 113  	if !c.ok() {
	 114  		return 0, nil, syscall.EINVAL
	 115  	}
	 116  	n, addr, err := c.readFrom(b, addr)
	 117  	if err != nil {
	 118  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	 119  	}
	 120  	return n, addr, err
	 121  }
	 122  
	 123  // ReadFrom implements the PacketConn ReadFrom method.
	 124  func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
	 125  	n, addr, err := c.readFromUDP(b, &UDPAddr{})
	 126  	if addr == nil {
	 127  		// Return Addr(nil), not Addr(*UDPConn(nil)).
	 128  		return n, nil, err
	 129  	}
	 130  	return n, addr, err
	 131  }
	 132  
	 133  // ReadMsgUDP reads a message from c, copying the payload into b and
	 134  // the associated out-of-band data into oob. It returns the number of
	 135  // bytes copied into b, the number of bytes copied into oob, the flags
	 136  // that were set on the message and the source address of the message.
	 137  //
	 138  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
	 139  // used to manipulate IP-level socket options in oob.
	 140  func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
	 141  	if !c.ok() {
	 142  		return 0, 0, 0, nil, syscall.EINVAL
	 143  	}
	 144  	n, oobn, flags, addr, err = c.readMsg(b, oob)
	 145  	if err != nil {
	 146  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	 147  	}
	 148  	return
	 149  }
	 150  
	 151  // WriteToUDP acts like WriteTo but takes a UDPAddr.
	 152  func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
	 153  	if !c.ok() {
	 154  		return 0, syscall.EINVAL
	 155  	}
	 156  	n, err := c.writeTo(b, addr)
	 157  	if err != nil {
	 158  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	 159  	}
	 160  	return n, err
	 161  }
	 162  
	 163  // WriteTo implements the PacketConn WriteTo method.
	 164  func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
	 165  	if !c.ok() {
	 166  		return 0, syscall.EINVAL
	 167  	}
	 168  	a, ok := addr.(*UDPAddr)
	 169  	if !ok {
	 170  		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
	 171  	}
	 172  	n, err := c.writeTo(b, a)
	 173  	if err != nil {
	 174  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
	 175  	}
	 176  	return n, err
	 177  }
	 178  
	 179  // WriteMsgUDP writes a message to addr via c if c isn't connected, or
	 180  // to c's remote address if c is connected (in which case addr must be
	 181  // nil). The payload is copied from b and the associated out-of-band
	 182  // data is copied from oob. It returns the number of payload and
	 183  // out-of-band bytes written.
	 184  //
	 185  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
	 186  // used to manipulate IP-level socket options in oob.
	 187  func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
	 188  	if !c.ok() {
	 189  		return 0, 0, syscall.EINVAL
	 190  	}
	 191  	n, oobn, err = c.writeMsg(b, oob, addr)
	 192  	if err != nil {
	 193  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
	 194  	}
	 195  	return
	 196  }
	 197  
	 198  func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
	 199  
	 200  // DialUDP acts like Dial for UDP networks.
	 201  //
	 202  // The network must be a UDP network name; see func Dial for details.
	 203  //
	 204  // If laddr is nil, a local address is automatically chosen.
	 205  // If the IP field of raddr is nil or an unspecified IP address, the
	 206  // local system is assumed.
	 207  func DialUDP(network string, laddr, raddr *UDPAddr) (*UDPConn, error) {
	 208  	switch network {
	 209  	case "udp", "udp4", "udp6":
	 210  	default:
	 211  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
	 212  	}
	 213  	if raddr == nil {
	 214  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
	 215  	}
	 216  	sd := &sysDialer{network: network, address: raddr.String()}
	 217  	c, err := sd.dialUDP(context.Background(), laddr, raddr)
	 218  	if err != nil {
	 219  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
	 220  	}
	 221  	return c, nil
	 222  }
	 223  
	 224  // ListenUDP acts like ListenPacket for UDP networks.
	 225  //
	 226  // The network must be a UDP network name; see func Dial for details.
	 227  //
	 228  // If the IP field of laddr is nil or an unspecified IP address,
	 229  // ListenUDP listens on all available IP addresses of the local system
	 230  // except multicast IP addresses.
	 231  // If the Port field of laddr is 0, a port number is automatically
	 232  // chosen.
	 233  func ListenUDP(network string, laddr *UDPAddr) (*UDPConn, error) {
	 234  	switch network {
	 235  	case "udp", "udp4", "udp6":
	 236  	default:
	 237  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
	 238  	}
	 239  	if laddr == nil {
	 240  		laddr = &UDPAddr{}
	 241  	}
	 242  	sl := &sysListener{network: network, address: laddr.String()}
	 243  	c, err := sl.listenUDP(context.Background(), laddr)
	 244  	if err != nil {
	 245  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
	 246  	}
	 247  	return c, nil
	 248  }
	 249  
	 250  // ListenMulticastUDP acts like ListenPacket for UDP networks but
	 251  // takes a group address on a specific network interface.
	 252  //
	 253  // The network must be a UDP network name; see func Dial for details.
	 254  //
	 255  // ListenMulticastUDP listens on all available IP addresses of the
	 256  // local system including the group, multicast IP address.
	 257  // If ifi is nil, ListenMulticastUDP uses the system-assigned
	 258  // multicast interface, although this is not recommended because the
	 259  // assignment depends on platforms and sometimes it might require
	 260  // routing configuration.
	 261  // If the Port field of gaddr is 0, a port number is automatically
	 262  // chosen.
	 263  //
	 264  // ListenMulticastUDP is just for convenience of simple, small
	 265  // applications. There are golang.org/x/net/ipv4 and
	 266  // golang.org/x/net/ipv6 packages for general purpose uses.
	 267  //
	 268  // Note that ListenMulticastUDP will set the IP_MULTICAST_LOOP socket option
	 269  // to 0 under IPPROTO_IP, to disable loopback of multicast packets.
	 270  func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
	 271  	switch network {
	 272  	case "udp", "udp4", "udp6":
	 273  	default:
	 274  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
	 275  	}
	 276  	if gaddr == nil || gaddr.IP == nil {
	 277  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
	 278  	}
	 279  	sl := &sysListener{network: network, address: gaddr.String()}
	 280  	c, err := sl.listenMulticastUDP(context.Background(), ifi, gaddr)
	 281  	if err != nil {
	 282  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
	 283  	}
	 284  	return c, nil
	 285  }
	 286
View as plain text