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- // Copyright 2009 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- package net
- import (
- "context"
- "internal/itoa"
- "net/netip"
- "syscall"
- )
- // BUG(mikio): On Plan 9, the ReadMsgUDP and
- // WriteMsgUDP methods of UDPConn are not implemented.
- // BUG(mikio): On Windows, the File method of UDPConn is not
- // implemented.
- // BUG(mikio): On JS, methods and functions related to UDPConn are not
- // implemented.
- // UDPAddr represents the address of a UDP end point.
- type UDPAddr struct {
- IP IP
- Port int
- Zone string // IPv6 scoped addressing zone
- }
- // AddrPort returns the UDPAddr a as a netip.AddrPort.
- //
- // If a.Port does not fit in a uint16, it's silently truncated.
- //
- // If a is nil, a zero value is returned.
- func (a *UDPAddr) AddrPort() netip.AddrPort {
- if a == nil {
- return netip.AddrPort{}
- }
- na, _ := netip.AddrFromSlice(a.IP)
- na = na.WithZone(a.Zone)
- return netip.AddrPortFrom(na, uint16(a.Port))
- }
- // Network returns the address's network name, "udp".
- func (a *UDPAddr) Network() string { return "udp" }
- func (a *UDPAddr) String() string {
- if a == nil {
- return "<nil>"
- }
- ip := ipEmptyString(a.IP)
- if a.Zone != "" {
- return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
- }
- return JoinHostPort(ip, itoa.Itoa(a.Port))
- }
- func (a *UDPAddr) isWildcard() bool {
- if a == nil || a.IP == nil {
- return true
- }
- return a.IP.IsUnspecified()
- }
- func (a *UDPAddr) opAddr() Addr {
- if a == nil {
- return nil
- }
- return a
- }
- // ResolveUDPAddr returns an address of UDP end point.
- //
- // The network must be a UDP network name.
- //
- // If the host in the address parameter is not a literal IP address or
- // the port is not a literal port number, ResolveUDPAddr resolves the
- // address to an address of UDP end point.
- // Otherwise, it parses the address as a pair of literal IP address
- // and port number.
- // The address parameter can use a host name, but this is not
- // recommended, because it will return at most one of the host name's
- // IP addresses.
- //
- // See func Dial for a description of the network and address
- // parameters.
- func ResolveUDPAddr(network, address string) (*UDPAddr, error) {
- switch network {
- case "udp", "udp4", "udp6":
- case "": // a hint wildcard for Go 1.0 undocumented behavior
- network = "udp"
- default:
- return nil, UnknownNetworkError(network)
- }
- addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
- if err != nil {
- return nil, err
- }
- return addrs.forResolve(network, address).(*UDPAddr), nil
- }
- // UDPAddrFromAddrPort returns addr as a UDPAddr. If addr.IsValid() is false,
- // then the returned UDPAddr will contain a nil IP field, indicating an
- // address family-agnostic unspecified address.
- func UDPAddrFromAddrPort(addr netip.AddrPort) *UDPAddr {
- return &UDPAddr{
- IP: addr.Addr().AsSlice(),
- Zone: addr.Addr().Zone(),
- Port: int(addr.Port()),
- }
- }
- // An addrPortUDPAddr is a netip.AddrPort-based UDP address that satisfies the Addr interface.
- type addrPortUDPAddr struct {
- netip.AddrPort
- }
- func (addrPortUDPAddr) Network() string { return "udp" }
- // UDPConn is the implementation of the Conn and PacketConn interfaces
- // for UDP network connections.
- type UDPConn struct {
- conn
- }
- // SyscallConn returns a raw network connection.
- // This implements the syscall.Conn interface.
- func (c *UDPConn) SyscallConn() (syscall.RawConn, error) {
- if !c.ok() {
- return nil, syscall.EINVAL
- }
- return newRawConn(c.fd)
- }
- // ReadFromUDP acts like ReadFrom but returns a UDPAddr.
- func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
- // This function is designed to allow the caller to control the lifetime
- // of the returned *UDPAddr and thereby prevent an allocation.
- // See https://blog.filippo.io/efficient-go-apis-with-the-inliner/.
- // The real work is done by readFromUDP, below.
- return c.readFromUDP(b, &UDPAddr{})
- }
- // readFromUDP implements ReadFromUDP.
- func (c *UDPConn) readFromUDP(b []byte, addr *UDPAddr) (int, *UDPAddr, error) {
- if !c.ok() {
- return 0, nil, syscall.EINVAL
- }
- n, addr, err := c.readFrom(b, addr)
- if err != nil {
- err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
- }
- return n, addr, err
- }
- // ReadFrom implements the PacketConn ReadFrom method.
- func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
- n, addr, err := c.readFromUDP(b, &UDPAddr{})
- if addr == nil {
- // Return Addr(nil), not Addr(*UDPConn(nil)).
- return n, nil, err
- }
- return n, addr, err
- }
- // ReadFromUDPAddrPort acts like ReadFrom but returns a netip.AddrPort.
- func (c *UDPConn) ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error) {
- if !c.ok() {
- return 0, netip.AddrPort{}, syscall.EINVAL
- }
- n, addr, err = c.readFromAddrPort(b)
- if err != nil {
- err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
- }
- return n, addr, err
- }
- // ReadMsgUDP reads a message from c, copying the payload into b and
- // the associated out-of-band data into oob. It returns the number of
- // bytes copied into b, the number of bytes copied into oob, the flags
- // that were set on the message and the source address of the message.
- //
- // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
- // used to manipulate IP-level socket options in oob.
- func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
- var ap netip.AddrPort
- n, oobn, flags, ap, err = c.ReadMsgUDPAddrPort(b, oob)
- if ap.IsValid() {
- addr = UDPAddrFromAddrPort(ap)
- }
- return
- }
- // ReadMsgUDPAddrPort is like ReadMsgUDP but returns an netip.AddrPort instead of a UDPAddr.
- func (c *UDPConn) ReadMsgUDPAddrPort(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
- if !c.ok() {
- return 0, 0, 0, netip.AddrPort{}, syscall.EINVAL
- }
- n, oobn, flags, addr, err = c.readMsg(b, oob)
- if err != nil {
- err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
- }
- return
- }
- // WriteToUDP acts like WriteTo but takes a UDPAddr.
- func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
- if !c.ok() {
- return 0, syscall.EINVAL
- }
- n, err := c.writeTo(b, addr)
- if err != nil {
- err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
- }
- return n, err
- }
- // WriteToUDPAddrPort acts like WriteTo but takes a netip.AddrPort.
- func (c *UDPConn) WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (int, error) {
- if !c.ok() {
- return 0, syscall.EINVAL
- }
- n, err := c.writeToAddrPort(b, addr)
- if err != nil {
- err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
- }
- return n, err
- }
- // WriteTo implements the PacketConn WriteTo method.
- func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
- if !c.ok() {
- return 0, syscall.EINVAL
- }
- a, ok := addr.(*UDPAddr)
- if !ok {
- return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
- }
- n, err := c.writeTo(b, a)
- if err != nil {
- err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
- }
- return n, err
- }
- // WriteMsgUDP writes a message to addr via c if c isn't connected, or
- // to c's remote address if c is connected (in which case addr must be
- // nil). The payload is copied from b and the associated out-of-band
- // data is copied from oob. It returns the number of payload and
- // out-of-band bytes written.
- //
- // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
- // used to manipulate IP-level socket options in oob.
- func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
- if !c.ok() {
- return 0, 0, syscall.EINVAL
- }
- n, oobn, err = c.writeMsg(b, oob, addr)
- if err != nil {
- err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
- }
- return
- }
- // WriteMsgUDPAddrPort is like WriteMsgUDP but takes a netip.AddrPort instead of a UDPAddr.
- func (c *UDPConn) WriteMsgUDPAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn int, err error) {
- if !c.ok() {
- return 0, 0, syscall.EINVAL
- }
- n, oobn, err = c.writeMsgAddrPort(b, oob, addr)
- if err != nil {
- err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
- }
- return
- }
- func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
- // DialUDP acts like Dial for UDP networks.
- //
- // The network must be a UDP network name; see func Dial for details.
- //
- // If laddr is nil, a local address is automatically chosen.
- // If the IP field of raddr is nil or an unspecified IP address, the
- // local system is assumed.
- func DialUDP(network string, laddr, raddr *UDPAddr) (*UDPConn, error) {
- switch network {
- case "udp", "udp4", "udp6":
- default:
- return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
- }
- if raddr == nil {
- return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
- }
- sd := &sysDialer{network: network, address: raddr.String()}
- c, err := sd.dialUDP(context.Background(), laddr, raddr)
- if err != nil {
- return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
- }
- return c, nil
- }
- // ListenUDP acts like ListenPacket for UDP networks.
- //
- // The network must be a UDP network name; see func Dial for details.
- //
- // If the IP field of laddr is nil or an unspecified IP address,
- // ListenUDP listens on all available IP addresses of the local system
- // except multicast IP addresses.
- // If the Port field of laddr is 0, a port number is automatically
- // chosen.
- func ListenUDP(network string, laddr *UDPAddr) (*UDPConn, error) {
- switch network {
- case "udp", "udp4", "udp6":
- default:
- return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
- }
- if laddr == nil {
- laddr = &UDPAddr{}
- }
- sl := &sysListener{network: network, address: laddr.String()}
- c, err := sl.listenUDP(context.Background(), laddr)
- if err != nil {
- return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
- }
- return c, nil
- }
- // ListenMulticastUDP acts like ListenPacket for UDP networks but
- // takes a group address on a specific network interface.
- //
- // The network must be a UDP network name; see func Dial for details.
- //
- // ListenMulticastUDP listens on all available IP addresses of the
- // local system including the group, multicast IP address.
- // If ifi is nil, ListenMulticastUDP uses the system-assigned
- // multicast interface, although this is not recommended because the
- // assignment depends on platforms and sometimes it might require
- // routing configuration.
- // If the Port field of gaddr is 0, a port number is automatically
- // chosen.
- //
- // ListenMulticastUDP is just for convenience of simple, small
- // applications. There are golang.org/x/net/ipv4 and
- // golang.org/x/net/ipv6 packages for general purpose uses.
- //
- // Note that ListenMulticastUDP will set the IP_MULTICAST_LOOP socket option
- // to 0 under IPPROTO_IP, to disable loopback of multicast packets.
- func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
- switch network {
- case "udp", "udp4", "udp6":
- default:
- return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
- }
- if gaddr == nil || gaddr.IP == nil {
- return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
- }
- sl := &sysListener{network: network, address: gaddr.String()}
- c, err := sl.listenMulticastUDP(context.Background(), ifi, gaddr)
- if err != nil {
- return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
- }
- return c, nil
- }
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