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Source file src/net/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  	"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  // 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 returns an address of UDP end point.
    57  //
    58  // The network must be a UDP network name.
    59  //
    60  // If the host in the address parameter is not a literal IP address or
    61  // the port is not a literal port number, ResolveUDPAddr resolves the
    62  // address to an address of UDP end point.
    63  // Otherwise, it parses the address as a pair of literal IP address
    64  // and port number.
    65  // The address parameter can use a host name, but this is not
    66  // recommended, because it will return at most one of the host name's
    67  // IP addresses.
    68  //
    69  // See func Dial for a description of the network and address
    70  // parameters.
    71  func ResolveUDPAddr(network, address string) (*UDPAddr, error) {
    72  	switch network {
    73  	case "udp", "udp4", "udp6":
    74  	case "": // a hint wildcard for Go 1.0 undocumented behavior
    75  		network = "udp"
    76  	default:
    77  		return nil, UnknownNetworkError(network)
    78  	}
    79  	addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
    80  	if err != nil {
    81  		return nil, err
    82  	}
    83  	return addrs.forResolve(network, address).(*UDPAddr), nil
    84  }
    85  
    86  // UDPConn is the implementation of the Conn and PacketConn interfaces
    87  // for UDP network connections.
    88  type UDPConn struct {
    89  	conn
    90  }
    91  
    92  // SyscallConn returns a raw network connection.
    93  // This implements the syscall.Conn interface.
    94  func (c *UDPConn) SyscallConn() (syscall.RawConn, error) {
    95  	if !c.ok() {
    96  		return nil, syscall.EINVAL
    97  	}
    98  	return newRawConn(c.fd)
    99  }
   100  
   101  // ReadFromUDP acts like ReadFrom but returns a UDPAddr.
   102  func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
   103  	if !c.ok() {
   104  		return 0, nil, syscall.EINVAL
   105  	}
   106  	n, addr, err := c.readFrom(b)
   107  	if err != nil {
   108  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   109  	}
   110  	return n, addr, err
   111  }
   112  
   113  // ReadFrom implements the PacketConn ReadFrom method.
   114  func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
   115  	if !c.ok() {
   116  		return 0, nil, syscall.EINVAL
   117  	}
   118  	n, addr, err := c.readFrom(b)
   119  	if err != nil {
   120  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   121  	}
   122  	if addr == nil {
   123  		return n, nil, err
   124  	}
   125  	return n, addr, err
   126  }
   127  
   128  // ReadMsgUDP reads a message from c, copying the payload into b and
   129  // the associated out-of-band data into oob. It returns the number of
   130  // bytes copied into b, the number of bytes copied into oob, the flags
   131  // that were set on the message and the source address of the message.
   132  //
   133  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
   134  // used to manipulate IP-level socket options in oob.
   135  func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
   136  	if !c.ok() {
   137  		return 0, 0, 0, nil, syscall.EINVAL
   138  	}
   139  	n, oobn, flags, addr, err = c.readMsg(b, oob)
   140  	if err != nil {
   141  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   142  	}
   143  	return
   144  }
   145  
   146  // WriteToUDP acts like WriteTo but takes a UDPAddr.
   147  func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
   148  	if !c.ok() {
   149  		return 0, syscall.EINVAL
   150  	}
   151  	n, err := c.writeTo(b, addr)
   152  	if err != nil {
   153  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   154  	}
   155  	return n, err
   156  }
   157  
   158  // WriteTo implements the PacketConn WriteTo method.
   159  func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
   160  	if !c.ok() {
   161  		return 0, syscall.EINVAL
   162  	}
   163  	a, ok := addr.(*UDPAddr)
   164  	if !ok {
   165  		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
   166  	}
   167  	n, err := c.writeTo(b, a)
   168  	if err != nil {
   169  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
   170  	}
   171  	return n, err
   172  }
   173  
   174  // WriteMsgUDP writes a message to addr via c if c isn't connected, or
   175  // to c's remote address if c is connected (in which case addr must be
   176  // nil). The payload is copied from b and the associated out-of-band
   177  // data is copied from oob. It returns the number of payload and
   178  // out-of-band bytes written.
   179  //
   180  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
   181  // used to manipulate IP-level socket options in oob.
   182  func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
   183  	if !c.ok() {
   184  		return 0, 0, syscall.EINVAL
   185  	}
   186  	n, oobn, err = c.writeMsg(b, oob, addr)
   187  	if err != nil {
   188  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   189  	}
   190  	return
   191  }
   192  
   193  func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
   194  
   195  // DialUDP acts like Dial for UDP networks.
   196  //
   197  // The network must be a UDP network name; see func Dial for details.
   198  //
   199  // If laddr is nil, a local address is automatically chosen.
   200  // If the IP field of raddr is nil or an unspecified IP address, the
   201  // local system is assumed.
   202  func DialUDP(network string, laddr, raddr *UDPAddr) (*UDPConn, error) {
   203  	switch network {
   204  	case "udp", "udp4", "udp6":
   205  	default:
   206  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
   207  	}
   208  	if raddr == nil {
   209  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   210  	}
   211  	c, err := dialUDP(context.Background(), network, laddr, raddr)
   212  	if err != nil {
   213  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   214  	}
   215  	return c, nil
   216  }
   217  
   218  // ListenUDP acts like ListenPacket for UDP networks.
   219  //
   220  // The network must be a UDP network name; see func Dial for details.
   221  //
   222  // If the IP field of laddr is nil or an unspecified IP address,
   223  // ListenUDP listens on all available IP addresses of the local system
   224  // except multicast IP addresses.
   225  // If the Port field of laddr is 0, a port number is automatically
   226  // chosen.
   227  func ListenUDP(network string, laddr *UDPAddr) (*UDPConn, error) {
   228  	switch network {
   229  	case "udp", "udp4", "udp6":
   230  	default:
   231  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
   232  	}
   233  	if laddr == nil {
   234  		laddr = &UDPAddr{}
   235  	}
   236  	c, err := listenUDP(context.Background(), network, laddr)
   237  	if err != nil {
   238  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
   239  	}
   240  	return c, nil
   241  }
   242  
   243  // ListenMulticastUDP acts like ListenPacket for UDP networks but
   244  // takes a group address on a specific network interface.
   245  //
   246  // The network must be a UDP network name; see func Dial for details.
   247  //
   248  // ListenMulticastUDP listens on all available IP addresses of the
   249  // local system including the group, multicast IP address.
   250  // If ifi is nil, ListenMulticastUDP uses the system-assigned
   251  // multicast interface, although this is not recommended because the
   252  // assignment depends on platforms and sometimes it might require
   253  // routing configuration.
   254  // If the Port field of gaddr is 0, a port number is automatically
   255  // chosen.
   256  //
   257  // ListenMulticastUDP is just for convenience of simple, small
   258  // applications. There are golang.org/x/net/ipv4 and
   259  // golang.org/x/net/ipv6 packages for general purpose uses.
   260  func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
   261  	switch network {
   262  	case "udp", "udp4", "udp6":
   263  	default:
   264  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
   265  	}
   266  	if gaddr == nil || gaddr.IP == nil {
   267  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
   268  	}
   269  	c, err := listenMulticastUDP(context.Background(), network, ifi, gaddr)
   270  	if err != nil {
   271  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
   272  	}
   273  	return c, nil
   274  }
   275  

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