mirror of
https://github.com/autc04/Retro68.git
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744 lines
23 KiB
Go
744 lines
23 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package net
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import (
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"context"
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"internal/nettrace"
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"syscall"
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"time"
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)
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// defaultTCPKeepAlive is a default constant value for TCPKeepAlive times
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// See golang.org/issue/31510
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const (
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defaultTCPKeepAlive = 15 * time.Second
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)
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// A Dialer contains options for connecting to an address.
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//
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// The zero value for each field is equivalent to dialing
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// without that option. Dialing with the zero value of Dialer
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// is therefore equivalent to just calling the Dial function.
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//
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// It is safe to call Dialer's methods concurrently.
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type Dialer struct {
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// Timeout is the maximum amount of time a dial will wait for
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// a connect to complete. If Deadline is also set, it may fail
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// earlier.
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//
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// The default is no timeout.
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//
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// When using TCP and dialing a host name with multiple IP
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// addresses, the timeout may be divided between them.
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//
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// With or without a timeout, the operating system may impose
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// its own earlier timeout. For instance, TCP timeouts are
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// often around 3 minutes.
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Timeout time.Duration
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// Deadline is the absolute point in time after which dials
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// will fail. If Timeout is set, it may fail earlier.
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// Zero means no deadline, or dependent on the operating system
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// as with the Timeout option.
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Deadline time.Time
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// LocalAddr is the local address to use when dialing an
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// address. The address must be of a compatible type for the
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// network being dialed.
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// If nil, a local address is automatically chosen.
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LocalAddr Addr
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// DualStack previously enabled RFC 6555 Fast Fallback
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// support, also known as "Happy Eyeballs", in which IPv4 is
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// tried soon if IPv6 appears to be misconfigured and
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// hanging.
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//
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// Deprecated: Fast Fallback is enabled by default. To
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// disable, set FallbackDelay to a negative value.
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DualStack bool
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// FallbackDelay specifies the length of time to wait before
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// spawning a RFC 6555 Fast Fallback connection. That is, this
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// is the amount of time to wait for IPv6 to succeed before
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// assuming that IPv6 is misconfigured and falling back to
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// IPv4.
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//
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// If zero, a default delay of 300ms is used.
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// A negative value disables Fast Fallback support.
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FallbackDelay time.Duration
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// KeepAlive specifies the interval between keep-alive
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// probes for an active network connection.
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// If zero, keep-alive probes are sent with a default value
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// (currently 15 seconds), if supported by the protocol and operating
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// system. Network protocols or operating systems that do
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// not support keep-alives ignore this field.
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// If negative, keep-alive probes are disabled.
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KeepAlive time.Duration
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// Resolver optionally specifies an alternate resolver to use.
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Resolver *Resolver
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// Cancel is an optional channel whose closure indicates that
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// the dial should be canceled. Not all types of dials support
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// cancellation.
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//
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// Deprecated: Use DialContext instead.
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Cancel <-chan struct{}
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// If Control is not nil, it is called after creating the network
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// connection but before actually dialing.
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//
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// Network and address parameters passed to Control method are not
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// necessarily the ones passed to Dial. For example, passing "tcp" to Dial
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// will cause the Control function to be called with "tcp4" or "tcp6".
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Control func(network, address string, c syscall.RawConn) error
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}
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func (d *Dialer) dualStack() bool { return d.FallbackDelay >= 0 }
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func minNonzeroTime(a, b time.Time) time.Time {
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if a.IsZero() {
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return b
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}
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if b.IsZero() || a.Before(b) {
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return a
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}
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return b
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}
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// deadline returns the earliest of:
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// - now+Timeout
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// - d.Deadline
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// - the context's deadline
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// Or zero, if none of Timeout, Deadline, or context's deadline is set.
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func (d *Dialer) deadline(ctx context.Context, now time.Time) (earliest time.Time) {
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if d.Timeout != 0 { // including negative, for historical reasons
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earliest = now.Add(d.Timeout)
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}
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if d, ok := ctx.Deadline(); ok {
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earliest = minNonzeroTime(earliest, d)
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}
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return minNonzeroTime(earliest, d.Deadline)
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}
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func (d *Dialer) resolver() *Resolver {
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if d.Resolver != nil {
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return d.Resolver
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}
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return DefaultResolver
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}
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// partialDeadline returns the deadline to use for a single address,
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// when multiple addresses are pending.
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func partialDeadline(now, deadline time.Time, addrsRemaining int) (time.Time, error) {
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if deadline.IsZero() {
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return deadline, nil
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}
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timeRemaining := deadline.Sub(now)
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if timeRemaining <= 0 {
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return time.Time{}, errTimeout
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}
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// Tentatively allocate equal time to each remaining address.
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timeout := timeRemaining / time.Duration(addrsRemaining)
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// If the time per address is too short, steal from the end of the list.
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const saneMinimum = 2 * time.Second
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if timeout < saneMinimum {
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if timeRemaining < saneMinimum {
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timeout = timeRemaining
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} else {
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timeout = saneMinimum
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}
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}
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return now.Add(timeout), nil
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}
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func (d *Dialer) fallbackDelay() time.Duration {
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if d.FallbackDelay > 0 {
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return d.FallbackDelay
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} else {
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return 300 * time.Millisecond
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}
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}
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func parseNetwork(ctx context.Context, network string, needsProto bool) (afnet string, proto int, err error) {
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i := last(network, ':')
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if i < 0 { // no colon
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switch network {
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case "tcp", "tcp4", "tcp6":
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case "udp", "udp4", "udp6":
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case "ip", "ip4", "ip6":
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if needsProto {
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return "", 0, UnknownNetworkError(network)
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}
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case "unix", "unixgram", "unixpacket":
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default:
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return "", 0, UnknownNetworkError(network)
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}
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return network, 0, nil
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}
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afnet = network[:i]
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switch afnet {
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case "ip", "ip4", "ip6":
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protostr := network[i+1:]
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proto, i, ok := dtoi(protostr)
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if !ok || i != len(protostr) {
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proto, err = lookupProtocol(ctx, protostr)
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if err != nil {
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return "", 0, err
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}
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}
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return afnet, proto, nil
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}
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return "", 0, UnknownNetworkError(network)
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}
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// resolveAddrList resolves addr using hint and returns a list of
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// addresses. The result contains at least one address when error is
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// nil.
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func (r *Resolver) resolveAddrList(ctx context.Context, op, network, addr string, hint Addr) (addrList, error) {
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afnet, _, err := parseNetwork(ctx, network, true)
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if err != nil {
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return nil, err
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}
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if op == "dial" && addr == "" {
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return nil, errMissingAddress
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}
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switch afnet {
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case "unix", "unixgram", "unixpacket":
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addr, err := ResolveUnixAddr(afnet, addr)
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if err != nil {
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return nil, err
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}
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if op == "dial" && hint != nil && addr.Network() != hint.Network() {
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return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
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}
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return addrList{addr}, nil
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}
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addrs, err := r.internetAddrList(ctx, afnet, addr)
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if err != nil || op != "dial" || hint == nil {
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return addrs, err
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}
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var (
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tcp *TCPAddr
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udp *UDPAddr
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ip *IPAddr
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wildcard bool
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)
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switch hint := hint.(type) {
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case *TCPAddr:
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tcp = hint
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wildcard = tcp.isWildcard()
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case *UDPAddr:
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udp = hint
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wildcard = udp.isWildcard()
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case *IPAddr:
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ip = hint
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wildcard = ip.isWildcard()
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}
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naddrs := addrs[:0]
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for _, addr := range addrs {
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if addr.Network() != hint.Network() {
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return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
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}
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switch addr := addr.(type) {
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case *TCPAddr:
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if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(tcp.IP) {
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continue
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}
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naddrs = append(naddrs, addr)
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case *UDPAddr:
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if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(udp.IP) {
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continue
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}
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naddrs = append(naddrs, addr)
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case *IPAddr:
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if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(ip.IP) {
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continue
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}
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naddrs = append(naddrs, addr)
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}
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}
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if len(naddrs) == 0 {
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return nil, &AddrError{Err: errNoSuitableAddress.Error(), Addr: hint.String()}
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}
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return naddrs, nil
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}
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// Dial connects to the address on the named network.
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//
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// Known networks are "tcp", "tcp4" (IPv4-only), "tcp6" (IPv6-only),
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// "udp", "udp4" (IPv4-only), "udp6" (IPv6-only), "ip", "ip4"
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// (IPv4-only), "ip6" (IPv6-only), "unix", "unixgram" and
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// "unixpacket".
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//
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// For TCP and UDP networks, the address has the form "host:port".
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// The host must be a literal IP address, or a host name that can be
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// resolved to IP addresses.
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// The port must be a literal port number or a service name.
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// If the host is a literal IPv6 address it must be enclosed in square
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// brackets, as in "[2001:db8::1]:80" or "[fe80::1%zone]:80".
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// The zone specifies the scope of the literal IPv6 address as defined
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// in RFC 4007.
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// The functions JoinHostPort and SplitHostPort manipulate a pair of
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// host and port in this form.
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// When using TCP, and the host resolves to multiple IP addresses,
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// Dial will try each IP address in order until one succeeds.
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//
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// Examples:
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// Dial("tcp", "golang.org:http")
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// Dial("tcp", "192.0.2.1:http")
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// Dial("tcp", "198.51.100.1:80")
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// Dial("udp", "[2001:db8::1]:domain")
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// Dial("udp", "[fe80::1%lo0]:53")
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// Dial("tcp", ":80")
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//
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// For IP networks, the network must be "ip", "ip4" or "ip6" followed
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// by a colon and a literal protocol number or a protocol name, and
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// the address has the form "host". The host must be a literal IP
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// address or a literal IPv6 address with zone.
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// It depends on each operating system how the operating system
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// behaves with a non-well known protocol number such as "0" or "255".
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//
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// Examples:
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// Dial("ip4:1", "192.0.2.1")
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// Dial("ip6:ipv6-icmp", "2001:db8::1")
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// Dial("ip6:58", "fe80::1%lo0")
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//
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// For TCP, UDP and IP networks, if the host is empty or a literal
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// unspecified IP address, as in ":80", "0.0.0.0:80" or "[::]:80" for
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// TCP and UDP, "", "0.0.0.0" or "::" for IP, the local system is
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// assumed.
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//
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// For Unix networks, the address must be a file system path.
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func Dial(network, address string) (Conn, error) {
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var d Dialer
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return d.Dial(network, address)
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}
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// DialTimeout acts like Dial but takes a timeout.
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//
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// The timeout includes name resolution, if required.
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// When using TCP, and the host in the address parameter resolves to
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// multiple IP addresses, the timeout is spread over each consecutive
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// dial, such that each is given an appropriate fraction of the time
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// to connect.
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//
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// See func Dial for a description of the network and address
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// parameters.
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func DialTimeout(network, address string, timeout time.Duration) (Conn, error) {
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d := Dialer{Timeout: timeout}
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return d.Dial(network, address)
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}
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// sysDialer contains a Dial's parameters and configuration.
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type sysDialer struct {
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Dialer
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network, address string
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}
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// Dial connects to the address on the named network.
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//
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// See func Dial for a description of the network and address
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// parameters.
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//
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// Dial uses context.Background internally; to specify the context, use
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// DialContext.
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func (d *Dialer) Dial(network, address string) (Conn, error) {
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return d.DialContext(context.Background(), network, address)
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}
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// DialContext connects to the address on the named network using
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// the provided context.
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//
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// The provided Context must be non-nil. If the context expires before
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// the connection is complete, an error is returned. Once successfully
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// connected, any expiration of the context will not affect the
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// connection.
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//
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// When using TCP, and the host in the address parameter resolves to multiple
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// network addresses, any dial timeout (from d.Timeout or ctx) is spread
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// over each consecutive dial, such that each is given an appropriate
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// fraction of the time to connect.
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// For example, if a host has 4 IP addresses and the timeout is 1 minute,
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// the connect to each single address will be given 15 seconds to complete
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// before trying the next one.
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//
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// See func Dial for a description of the network and address
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// parameters.
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func (d *Dialer) DialContext(ctx context.Context, network, address string) (Conn, error) {
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if ctx == nil {
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panic("nil context")
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}
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deadline := d.deadline(ctx, time.Now())
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if !deadline.IsZero() {
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if d, ok := ctx.Deadline(); !ok || deadline.Before(d) {
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subCtx, cancel := context.WithDeadline(ctx, deadline)
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defer cancel()
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ctx = subCtx
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}
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}
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if oldCancel := d.Cancel; oldCancel != nil {
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subCtx, cancel := context.WithCancel(ctx)
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defer cancel()
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go func() {
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select {
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case <-oldCancel:
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cancel()
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case <-subCtx.Done():
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}
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}()
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ctx = subCtx
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}
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// Shadow the nettrace (if any) during resolve so Connect events don't fire for DNS lookups.
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resolveCtx := ctx
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if trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace); trace != nil {
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shadow := *trace
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shadow.ConnectStart = nil
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shadow.ConnectDone = nil
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resolveCtx = context.WithValue(resolveCtx, nettrace.TraceKey{}, &shadow)
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}
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addrs, err := d.resolver().resolveAddrList(resolveCtx, "dial", network, address, d.LocalAddr)
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if err != nil {
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return nil, &OpError{Op: "dial", Net: network, Source: nil, Addr: nil, Err: err}
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}
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sd := &sysDialer{
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Dialer: *d,
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network: network,
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address: address,
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}
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var primaries, fallbacks addrList
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if d.dualStack() && network == "tcp" {
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primaries, fallbacks = addrs.partition(isIPv4)
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} else {
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primaries = addrs
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}
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var c Conn
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if len(fallbacks) > 0 {
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c, err = sd.dialParallel(ctx, primaries, fallbacks)
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} else {
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c, err = sd.dialSerial(ctx, primaries)
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}
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if err != nil {
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return nil, err
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}
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if tc, ok := c.(*TCPConn); ok && d.KeepAlive >= 0 {
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setKeepAlive(tc.fd, true)
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ka := d.KeepAlive
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if d.KeepAlive == 0 {
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ka = defaultTCPKeepAlive
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}
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setKeepAlivePeriod(tc.fd, ka)
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testHookSetKeepAlive(ka)
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}
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return c, nil
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}
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// dialParallel races two copies of dialSerial, giving the first a
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// head start. It returns the first established connection and
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// closes the others. Otherwise it returns an error from the first
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// primary address.
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func (sd *sysDialer) dialParallel(ctx context.Context, primaries, fallbacks addrList) (Conn, error) {
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if len(fallbacks) == 0 {
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return sd.dialSerial(ctx, primaries)
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}
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returned := make(chan struct{})
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defer close(returned)
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type dialResult struct {
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Conn
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error
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primary bool
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done bool
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}
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results := make(chan dialResult) // unbuffered
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startRacer := func(ctx context.Context, primary bool) {
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ras := primaries
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if !primary {
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ras = fallbacks
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}
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c, err := sd.dialSerial(ctx, ras)
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select {
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case results <- dialResult{Conn: c, error: err, primary: primary, done: true}:
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case <-returned:
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if c != nil {
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c.Close()
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}
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}
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}
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var primary, fallback dialResult
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// Start the main racer.
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primaryCtx, primaryCancel := context.WithCancel(ctx)
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defer primaryCancel()
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go startRacer(primaryCtx, true)
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// Start the timer for the fallback racer.
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fallbackTimer := time.NewTimer(sd.fallbackDelay())
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defer fallbackTimer.Stop()
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for {
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select {
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case <-fallbackTimer.C:
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fallbackCtx, fallbackCancel := context.WithCancel(ctx)
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defer fallbackCancel()
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go startRacer(fallbackCtx, false)
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case res := <-results:
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if res.error == nil {
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return res.Conn, nil
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}
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if res.primary {
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primary = res
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} else {
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fallback = res
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}
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if primary.done && fallback.done {
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return nil, primary.error
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}
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if res.primary && fallbackTimer.Stop() {
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// If we were able to stop the timer, that means it
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// was running (hadn't yet started the fallback), but
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// we just got an error on the primary path, so start
|
|
// the fallback immediately (in 0 nanoseconds).
|
|
fallbackTimer.Reset(0)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// dialSerial connects to a list of addresses in sequence, returning
|
|
// either the first successful connection, or the first error.
|
|
func (sd *sysDialer) dialSerial(ctx context.Context, ras addrList) (Conn, error) {
|
|
var firstErr error // The error from the first address is most relevant.
|
|
|
|
for i, ra := range ras {
|
|
select {
|
|
case <-ctx.Done():
|
|
return nil, &OpError{Op: "dial", Net: sd.network, Source: sd.LocalAddr, Addr: ra, Err: mapErr(ctx.Err())}
|
|
default:
|
|
}
|
|
|
|
dialCtx := ctx
|
|
if deadline, hasDeadline := ctx.Deadline(); hasDeadline {
|
|
partialDeadline, err := partialDeadline(time.Now(), deadline, len(ras)-i)
|
|
if err != nil {
|
|
// Ran out of time.
|
|
if firstErr == nil {
|
|
firstErr = &OpError{Op: "dial", Net: sd.network, Source: sd.LocalAddr, Addr: ra, Err: err}
|
|
}
|
|
break
|
|
}
|
|
if partialDeadline.Before(deadline) {
|
|
var cancel context.CancelFunc
|
|
dialCtx, cancel = context.WithDeadline(ctx, partialDeadline)
|
|
defer cancel()
|
|
}
|
|
}
|
|
|
|
c, err := sd.dialSingle(dialCtx, ra)
|
|
if err == nil {
|
|
return c, nil
|
|
}
|
|
if firstErr == nil {
|
|
firstErr = err
|
|
}
|
|
}
|
|
|
|
if firstErr == nil {
|
|
firstErr = &OpError{Op: "dial", Net: sd.network, Source: nil, Addr: nil, Err: errMissingAddress}
|
|
}
|
|
return nil, firstErr
|
|
}
|
|
|
|
// dialSingle attempts to establish and returns a single connection to
|
|
// the destination address.
|
|
func (sd *sysDialer) dialSingle(ctx context.Context, ra Addr) (c Conn, err error) {
|
|
trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace)
|
|
if trace != nil {
|
|
raStr := ra.String()
|
|
if trace.ConnectStart != nil {
|
|
trace.ConnectStart(sd.network, raStr)
|
|
}
|
|
if trace.ConnectDone != nil {
|
|
defer func() { trace.ConnectDone(sd.network, raStr, err) }()
|
|
}
|
|
}
|
|
la := sd.LocalAddr
|
|
switch ra := ra.(type) {
|
|
case *TCPAddr:
|
|
la, _ := la.(*TCPAddr)
|
|
c, err = sd.dialTCP(ctx, la, ra)
|
|
case *UDPAddr:
|
|
la, _ := la.(*UDPAddr)
|
|
c, err = sd.dialUDP(ctx, la, ra)
|
|
case *IPAddr:
|
|
la, _ := la.(*IPAddr)
|
|
c, err = sd.dialIP(ctx, la, ra)
|
|
case *UnixAddr:
|
|
la, _ := la.(*UnixAddr)
|
|
c, err = sd.dialUnix(ctx, la, ra)
|
|
default:
|
|
return nil, &OpError{Op: "dial", Net: sd.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: sd.address}}
|
|
}
|
|
if err != nil {
|
|
return nil, &OpError{Op: "dial", Net: sd.network, Source: la, Addr: ra, Err: err} // c is non-nil interface containing nil pointer
|
|
}
|
|
return c, nil
|
|
}
|
|
|
|
// ListenConfig contains options for listening to an address.
|
|
type ListenConfig struct {
|
|
// If Control is not nil, it is called after creating the network
|
|
// connection but before binding it to the operating system.
|
|
//
|
|
// Network and address parameters passed to Control method are not
|
|
// necessarily the ones passed to Listen. For example, passing "tcp" to
|
|
// Listen will cause the Control function to be called with "tcp4" or "tcp6".
|
|
Control func(network, address string, c syscall.RawConn) error
|
|
|
|
// KeepAlive specifies the keep-alive period for network
|
|
// connections accepted by this listener.
|
|
// If zero, keep-alives are enabled if supported by the protocol
|
|
// and operating system. Network protocols or operating systems
|
|
// that do not support keep-alives ignore this field.
|
|
// If negative, keep-alives are disabled.
|
|
KeepAlive time.Duration
|
|
}
|
|
|
|
// Listen announces on the local network address.
|
|
//
|
|
// See func Listen for a description of the network and address
|
|
// parameters.
|
|
func (lc *ListenConfig) Listen(ctx context.Context, network, address string) (Listener, error) {
|
|
addrs, err := DefaultResolver.resolveAddrList(ctx, "listen", network, address, nil)
|
|
if err != nil {
|
|
return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: nil, Err: err}
|
|
}
|
|
sl := &sysListener{
|
|
ListenConfig: *lc,
|
|
network: network,
|
|
address: address,
|
|
}
|
|
var l Listener
|
|
la := addrs.first(isIPv4)
|
|
switch la := la.(type) {
|
|
case *TCPAddr:
|
|
l, err = sl.listenTCP(ctx, la)
|
|
case *UnixAddr:
|
|
l, err = sl.listenUnix(ctx, la)
|
|
default:
|
|
return nil, &OpError{Op: "listen", Net: sl.network, Source: nil, Addr: la, Err: &AddrError{Err: "unexpected address type", Addr: address}}
|
|
}
|
|
if err != nil {
|
|
return nil, &OpError{Op: "listen", Net: sl.network, Source: nil, Addr: la, Err: err} // l is non-nil interface containing nil pointer
|
|
}
|
|
return l, nil
|
|
}
|
|
|
|
// ListenPacket announces on the local network address.
|
|
//
|
|
// See func ListenPacket for a description of the network and address
|
|
// parameters.
|
|
func (lc *ListenConfig) ListenPacket(ctx context.Context, network, address string) (PacketConn, error) {
|
|
addrs, err := DefaultResolver.resolveAddrList(ctx, "listen", network, address, nil)
|
|
if err != nil {
|
|
return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: nil, Err: err}
|
|
}
|
|
sl := &sysListener{
|
|
ListenConfig: *lc,
|
|
network: network,
|
|
address: address,
|
|
}
|
|
var c PacketConn
|
|
la := addrs.first(isIPv4)
|
|
switch la := la.(type) {
|
|
case *UDPAddr:
|
|
c, err = sl.listenUDP(ctx, la)
|
|
case *IPAddr:
|
|
c, err = sl.listenIP(ctx, la)
|
|
case *UnixAddr:
|
|
c, err = sl.listenUnixgram(ctx, la)
|
|
default:
|
|
return nil, &OpError{Op: "listen", Net: sl.network, Source: nil, Addr: la, Err: &AddrError{Err: "unexpected address type", Addr: address}}
|
|
}
|
|
if err != nil {
|
|
return nil, &OpError{Op: "listen", Net: sl.network, Source: nil, Addr: la, Err: err} // c is non-nil interface containing nil pointer
|
|
}
|
|
return c, nil
|
|
}
|
|
|
|
// sysListener contains a Listen's parameters and configuration.
|
|
type sysListener struct {
|
|
ListenConfig
|
|
network, address string
|
|
}
|
|
|
|
// Listen announces on the local network address.
|
|
//
|
|
// The network must be "tcp", "tcp4", "tcp6", "unix" or "unixpacket".
|
|
//
|
|
// For TCP networks, if the host in the address parameter is empty or
|
|
// a literal unspecified IP address, Listen listens on all available
|
|
// unicast and anycast IP addresses of the local system.
|
|
// To only use IPv4, use network "tcp4".
|
|
// The address can use a host name, but this is not recommended,
|
|
// because it will create a listener for at most one of the host's IP
|
|
// addresses.
|
|
// If the port in the address parameter is empty or "0", as in
|
|
// "127.0.0.1:" or "[::1]:0", a port number is automatically chosen.
|
|
// The Addr method of Listener can be used to discover the chosen
|
|
// port.
|
|
//
|
|
// See func Dial for a description of the network and address
|
|
// parameters.
|
|
//
|
|
// Listen uses context.Background internally; to specify the context, use
|
|
// ListenConfig.Listen.
|
|
func Listen(network, address string) (Listener, error) {
|
|
var lc ListenConfig
|
|
return lc.Listen(context.Background(), network, address)
|
|
}
|
|
|
|
// ListenPacket announces on the local network address.
|
|
//
|
|
// The network must be "udp", "udp4", "udp6", "unixgram", or an IP
|
|
// transport. The IP transports are "ip", "ip4", or "ip6" followed by
|
|
// a colon and a literal protocol number or a protocol name, as in
|
|
// "ip:1" or "ip:icmp".
|
|
//
|
|
// For UDP and IP networks, if the host in the address parameter is
|
|
// empty or a literal unspecified IP address, ListenPacket listens on
|
|
// all available IP addresses of the local system except multicast IP
|
|
// addresses.
|
|
// To only use IPv4, use network "udp4" or "ip4:proto".
|
|
// The address can use a host name, but this is not recommended,
|
|
// because it will create a listener for at most one of the host's IP
|
|
// addresses.
|
|
// If the port in the address parameter is empty or "0", as in
|
|
// "127.0.0.1:" or "[::1]:0", a port number is automatically chosen.
|
|
// The LocalAddr method of PacketConn can be used to discover the
|
|
// chosen port.
|
|
//
|
|
// See func Dial for a description of the network and address
|
|
// parameters.
|
|
//
|
|
// ListenPacket uses context.Background internally; to specify the context, use
|
|
// ListenConfig.ListenPacket.
|
|
func ListenPacket(network, address string) (PacketConn, error) {
|
|
var lc ListenConfig
|
|
return lc.ListenPacket(context.Background(), network, address)
|
|
}
|