mirror of https://go.googlesource.com/go
453 lines
14 KiB
Go
453 lines
14 KiB
Go
// Copyright 2009 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/itoa"
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"io"
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"net/netip"
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"os"
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"syscall"
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"time"
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)
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// BUG(mikio): On JS and Windows, the File method of TCPConn and
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// TCPListener is not implemented.
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// TCPAddr represents the address of a TCP end point.
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type TCPAddr struct {
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IP IP
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Port int
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Zone string // IPv6 scoped addressing zone
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}
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// AddrPort returns the [TCPAddr] a as a [netip.AddrPort].
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//
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// If a.Port does not fit in a uint16, it's silently truncated.
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//
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// If a is nil, a zero value is returned.
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func (a *TCPAddr) AddrPort() netip.AddrPort {
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if a == nil {
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return netip.AddrPort{}
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}
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na, _ := netip.AddrFromSlice(a.IP)
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na = na.WithZone(a.Zone)
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return netip.AddrPortFrom(na, uint16(a.Port))
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}
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// Network returns the address's network name, "tcp".
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func (a *TCPAddr) Network() string { return "tcp" }
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func (a *TCPAddr) String() string {
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if a == nil {
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return "<nil>"
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}
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ip := ipEmptyString(a.IP)
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if a.Zone != "" {
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return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
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}
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return JoinHostPort(ip, itoa.Itoa(a.Port))
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}
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func (a *TCPAddr) isWildcard() bool {
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if a == nil || a.IP == nil {
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return true
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}
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return a.IP.IsUnspecified()
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}
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func (a *TCPAddr) opAddr() Addr {
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if a == nil {
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return nil
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}
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return a
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}
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// ResolveTCPAddr returns an address of TCP end point.
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//
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// The network must be a TCP network name.
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//
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// If the host in the address parameter is not a literal IP address or
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// the port is not a literal port number, ResolveTCPAddr resolves the
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// address to an address of TCP end point.
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// Otherwise, it parses the address as a pair of literal IP address
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// and port number.
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// The address parameter can use a host name, but this is not
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// recommended, because it will return at most one of the host name's
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// IP addresses.
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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 ResolveTCPAddr(network, address string) (*TCPAddr, error) {
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switch network {
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case "tcp", "tcp4", "tcp6":
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case "": // a hint wildcard for Go 1.0 undocumented behavior
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network = "tcp"
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default:
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return nil, UnknownNetworkError(network)
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}
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addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
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if err != nil {
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return nil, err
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}
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return addrs.forResolve(network, address).(*TCPAddr), nil
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}
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// TCPAddrFromAddrPort returns addr as a [TCPAddr]. If addr.IsValid() is false,
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// then the returned TCPAddr will contain a nil IP field, indicating an
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// address family-agnostic unspecified address.
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func TCPAddrFromAddrPort(addr netip.AddrPort) *TCPAddr {
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return &TCPAddr{
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IP: addr.Addr().AsSlice(),
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Zone: addr.Addr().Zone(),
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Port: int(addr.Port()),
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}
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}
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// TCPConn is an implementation of the [Conn] interface for TCP network
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// connections.
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type TCPConn struct {
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conn
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}
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// KeepAliveConfig contains TCP keep-alive options.
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//
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// If the Idle, Interval, or Count fields are zero, a default value is chosen.
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// If a field is negative, the corresponding socket-level option will be left unchanged.
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//
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// Note that prior to Windows 10 version 1709, neither setting Idle and Interval
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// separately nor changing Count (which is usually 10) is supported.
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// Therefore, it's recommended to set both Idle and Interval to non-negative values
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// in conjunction with a -1 for Count on those old Windows if you intend to customize
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// the TCP keep-alive settings.
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// By contrast, if only one of Idle and Interval is set to a non-negative value,
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// the other will be set to the system default value, and ultimately,
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// set both Idle and Interval to negative values if you want to leave them unchanged.
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//
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// Note that Solaris and its derivatives do not support setting Interval to a non-negative value
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// and Count to a negative value, or vice-versa.
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type KeepAliveConfig struct {
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// If Enable is true, keep-alive probes are enabled.
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Enable bool
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// Idle is the time that the connection must be idle before
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// the first keep-alive probe is sent.
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// If zero, a default value of 15 seconds is used.
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Idle time.Duration
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// Interval is the time between keep-alive probes.
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// If zero, a default value of 15 seconds is used.
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Interval time.Duration
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// Count is the maximum number of keep-alive probes that
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// can go unanswered before dropping a connection.
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// If zero, a default value of 9 is used.
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Count int
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}
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// SyscallConn returns a raw network connection.
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// This implements the [syscall.Conn] interface.
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func (c *TCPConn) SyscallConn() (syscall.RawConn, error) {
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if !c.ok() {
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return nil, syscall.EINVAL
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}
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return newRawConn(c.fd), nil
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}
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// ReadFrom implements the [io.ReaderFrom] ReadFrom method.
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func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
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if !c.ok() {
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return 0, syscall.EINVAL
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}
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n, err := c.readFrom(r)
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if err != nil && err != io.EOF {
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err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return n, err
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}
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// WriteTo implements the io.WriterTo WriteTo method.
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func (c *TCPConn) WriteTo(w io.Writer) (int64, error) {
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if !c.ok() {
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return 0, syscall.EINVAL
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}
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n, err := c.writeTo(w)
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if err != nil && err != io.EOF {
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err = &OpError{Op: "writeto", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return n, err
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}
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// CloseRead shuts down the reading side of the TCP connection.
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// Most callers should just use Close.
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func (c *TCPConn) CloseRead() error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := c.fd.closeRead(); err != nil {
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return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// CloseWrite shuts down the writing side of the TCP connection.
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// Most callers should just use Close.
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func (c *TCPConn) CloseWrite() error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := c.fd.closeWrite(); err != nil {
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return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetLinger sets the behavior of Close on a connection which still
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// has data waiting to be sent or to be acknowledged.
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//
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// If sec < 0 (the default), the operating system finishes sending the
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// data in the background.
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//
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// If sec == 0, the operating system discards any unsent or
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// unacknowledged data.
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//
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// If sec > 0, the data is sent in the background as with sec < 0.
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// On some operating systems including Linux, this may cause Close to block
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// until all data has been sent or discarded.
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// On some operating systems after sec seconds have elapsed any remaining
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// unsent data may be discarded.
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func (c *TCPConn) SetLinger(sec int) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setLinger(c.fd, sec); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetKeepAlive sets whether the operating system should send
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// keep-alive messages on the connection.
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func (c *TCPConn) SetKeepAlive(keepalive bool) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setKeepAlive(c.fd, keepalive); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetKeepAlivePeriod sets the duration the connection needs to
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// remain idle before TCP starts sending keepalive probes.
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//
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// Note that calling this method on Windows prior to Windows 10 version 1709
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// will reset the KeepAliveInterval to the default system value, which is normally 1 second.
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func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setKeepAliveIdle(c.fd, d); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetNoDelay controls whether the operating system should delay
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// packet transmission in hopes of sending fewer packets (Nagle's
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// algorithm). The default is true (no delay), meaning that data is
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// sent as soon as possible after a Write.
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func (c *TCPConn) SetNoDelay(noDelay bool) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setNoDelay(c.fd, noDelay); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// MultipathTCP reports whether the ongoing connection is using MPTCP.
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//
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// If Multipath TCP is not supported by the host, by the other peer or
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// intentionally / accidentally filtered out by a device in between, a
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// fallback to TCP will be done. This method does its best to check if
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// MPTCP is still being used or not.
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//
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// On Linux, more conditions are verified on kernels >= v5.16, improving
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// the results.
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func (c *TCPConn) MultipathTCP() (bool, error) {
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if !c.ok() {
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return false, syscall.EINVAL
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}
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return isUsingMultipathTCP(c.fd), nil
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}
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func newTCPConn(fd *netFD, keepAliveIdle time.Duration, keepAliveCfg KeepAliveConfig, preKeepAliveHook func(*netFD), keepAliveHook func(KeepAliveConfig)) *TCPConn {
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setNoDelay(fd, true)
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if !keepAliveCfg.Enable && keepAliveIdle >= 0 {
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keepAliveCfg = KeepAliveConfig{
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Enable: true,
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Idle: keepAliveIdle,
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}
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}
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c := &TCPConn{conn{fd}}
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if keepAliveCfg.Enable {
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if preKeepAliveHook != nil {
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preKeepAliveHook(fd)
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}
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c.SetKeepAliveConfig(keepAliveCfg)
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if keepAliveHook != nil {
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keepAliveHook(keepAliveCfg)
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}
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}
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return c
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}
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// DialTCP acts like [Dial] for TCP networks.
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//
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// The network must be a TCP network name; see func Dial for details.
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//
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// If laddr is nil, a local address is automatically chosen.
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// If the IP field of raddr is nil or an unspecified IP address, the
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// local system is assumed.
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func DialTCP(network string, laddr, raddr *TCPAddr) (*TCPConn, error) {
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switch network {
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case "tcp", "tcp4", "tcp6":
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default:
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return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
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}
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if raddr == nil {
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return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
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}
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sd := &sysDialer{network: network, address: raddr.String()}
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c, err := sd.dialTCP(context.Background(), laddr, raddr)
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if err != nil {
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return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
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}
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return c, nil
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}
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// TCPListener is a TCP network listener. Clients should typically
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// use variables of type [Listener] instead of assuming TCP.
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type TCPListener struct {
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fd *netFD
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lc ListenConfig
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}
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// SyscallConn returns a raw network connection.
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// This implements the [syscall.Conn] interface.
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//
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// The returned RawConn only supports calling Control. Read and
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// Write return an error.
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func (l *TCPListener) SyscallConn() (syscall.RawConn, error) {
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if !l.ok() {
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return nil, syscall.EINVAL
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}
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return newRawListener(l.fd), nil
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}
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// AcceptTCP accepts the next incoming call and returns the new
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// connection.
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func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
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if !l.ok() {
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return nil, syscall.EINVAL
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}
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c, err := l.accept()
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if err != nil {
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return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return c, nil
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}
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// Accept implements the Accept method in the [Listener] interface; it
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// waits for the next call and returns a generic [Conn].
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func (l *TCPListener) Accept() (Conn, error) {
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if !l.ok() {
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return nil, syscall.EINVAL
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}
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c, err := l.accept()
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if err != nil {
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return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return c, nil
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}
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// Close stops listening on the TCP address.
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// Already Accepted connections are not closed.
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func (l *TCPListener) Close() error {
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if !l.ok() {
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return syscall.EINVAL
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}
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if err := l.close(); err != nil {
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return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return nil
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}
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// Addr returns the listener's network address, a [*TCPAddr].
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// The Addr returned is shared by all invocations of Addr, so
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// do not modify it.
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func (l *TCPListener) Addr() Addr { return l.fd.laddr }
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// SetDeadline sets the deadline associated with the listener.
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// A zero time value disables the deadline.
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func (l *TCPListener) SetDeadline(t time.Time) error {
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if !l.ok() {
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return syscall.EINVAL
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}
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return l.fd.SetDeadline(t)
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}
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// File returns a copy of the underlying [os.File].
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// It is the caller's responsibility to close f when finished.
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// Closing l does not affect f, and closing f does not affect l.
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//
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// The returned os.File's file descriptor is different from the
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// connection's. Attempting to change properties of the original
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// using this duplicate may or may not have the desired effect.
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func (l *TCPListener) File() (f *os.File, err error) {
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if !l.ok() {
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return nil, syscall.EINVAL
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}
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f, err = l.file()
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if err != nil {
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return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return
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}
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// ListenTCP acts like [Listen] for TCP networks.
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//
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// The network must be a TCP network name; see func Dial for details.
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//
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// If the IP field of laddr is nil or an unspecified IP address,
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// ListenTCP listens on all available unicast and anycast IP addresses
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// of the local system.
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// If the Port field of laddr is 0, a port number is automatically
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// chosen.
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func ListenTCP(network string, laddr *TCPAddr) (*TCPListener, error) {
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switch network {
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case "tcp", "tcp4", "tcp6":
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default:
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return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
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}
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if laddr == nil {
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laddr = &TCPAddr{}
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}
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sl := &sysListener{network: network, address: laddr.String()}
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ln, err := sl.listenTCP(context.Background(), laddr)
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if err != nil {
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return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
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}
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return ln, nil
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}
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// roundDurationUp rounds d to the next multiple of to.
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func roundDurationUp(d time.Duration, to time.Duration) time.Duration {
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return (d + to - 1) / to
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}
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