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

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