10533c3e73
Instead of hard-coding exactly two sources from which to receive packets (an IPv4 source and an IPv6 source), allow the conn.Bind to specify a set of sources. Beneficial consequences: * If there's no IPv6 support on a system, conn.Bind.Open can choose not to return a receive function for it, which is simpler than tracking that state in the bind. This simplification removes existing data races from both conn.StdNetBind and bindtest.ChannelBind. * If there are more than two sources on a system, the conn.Bind no longer needs to add a separate muxing layer. Signed-off-by: Josh Bleecher Snyder <josharian@gmail.com>
580 lines
11 KiB
Go
580 lines
11 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
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*/
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package conn
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import (
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"errors"
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"net"
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"strconv"
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"sync"
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"syscall"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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type ipv4Source struct {
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Src [4]byte
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Ifindex int32
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}
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type ipv6Source struct {
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src [16]byte
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// ifindex belongs in dst.ZoneId
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}
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type LinuxSocketEndpoint struct {
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mu sync.Mutex
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dst [unsafe.Sizeof(unix.SockaddrInet6{})]byte
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src [unsafe.Sizeof(ipv6Source{})]byte
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isV6 bool
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}
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func (endpoint *LinuxSocketEndpoint) Src4() *ipv4Source { return endpoint.src4() }
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func (endpoint *LinuxSocketEndpoint) Dst4() *unix.SockaddrInet4 { return endpoint.dst4() }
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func (endpoint *LinuxSocketEndpoint) IsV6() bool { return endpoint.isV6 }
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func (endpoint *LinuxSocketEndpoint) src4() *ipv4Source {
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return (*ipv4Source)(unsafe.Pointer(&endpoint.src[0]))
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}
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func (endpoint *LinuxSocketEndpoint) src6() *ipv6Source {
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return (*ipv6Source)(unsafe.Pointer(&endpoint.src[0]))
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}
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func (endpoint *LinuxSocketEndpoint) dst4() *unix.SockaddrInet4 {
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return (*unix.SockaddrInet4)(unsafe.Pointer(&endpoint.dst[0]))
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}
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func (endpoint *LinuxSocketEndpoint) dst6() *unix.SockaddrInet6 {
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return (*unix.SockaddrInet6)(unsafe.Pointer(&endpoint.dst[0]))
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}
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// LinuxSocketBind uses sendmsg and recvmsg to implement a full bind with sticky sockets on Linux.
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type LinuxSocketBind struct {
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// mu guards sock4 and sock6 and the associated fds.
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// As long as someone holds mu (read or write), the associated fds are valid.
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mu sync.RWMutex
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sock4 int
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sock6 int
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}
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func NewLinuxSocketBind() Bind { return &LinuxSocketBind{sock4: -1, sock6: -1} }
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func NewDefaultBind() Bind { return NewLinuxSocketBind() }
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var _ Endpoint = (*LinuxSocketEndpoint)(nil)
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var _ Bind = (*LinuxSocketBind)(nil)
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func (*LinuxSocketBind) ParseEndpoint(s string) (Endpoint, error) {
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var end LinuxSocketEndpoint
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addr, err := parseEndpoint(s)
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if err != nil {
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return nil, err
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}
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ipv4 := addr.IP.To4()
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if ipv4 != nil {
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dst := end.dst4()
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end.isV6 = false
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dst.Port = addr.Port
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copy(dst.Addr[:], ipv4)
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end.ClearSrc()
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return &end, nil
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}
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ipv6 := addr.IP.To16()
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if ipv6 != nil {
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zone, err := zoneToUint32(addr.Zone)
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if err != nil {
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return nil, err
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}
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dst := end.dst6()
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end.isV6 = true
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dst.Port = addr.Port
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dst.ZoneId = zone
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copy(dst.Addr[:], ipv6[:])
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end.ClearSrc()
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return &end, nil
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}
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return nil, errors.New("invalid IP address")
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}
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func (bind *LinuxSocketBind) Open(port uint16) ([]ReceiveFunc, uint16, error) {
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bind.mu.Lock()
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defer bind.mu.Unlock()
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var err error
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var newPort uint16
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var tries int
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if bind.sock4 != -1 || bind.sock6 != -1 {
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return nil, 0, ErrBindAlreadyOpen
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}
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originalPort := port
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again:
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port = originalPort
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var sock4, sock6 int
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// Attempt ipv6 bind, update port if successful.
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sock6, newPort, err = create6(port)
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if err != nil {
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if !errors.Is(err, syscall.EAFNOSUPPORT) {
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return nil, 0, err
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}
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} else {
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port = newPort
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}
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// Attempt ipv4 bind, update port if successful.
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sock4, newPort, err = create4(port)
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if err != nil {
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if originalPort == 0 && errors.Is(err, syscall.EADDRINUSE) && tries < 100 {
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unix.Close(sock6)
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tries++
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goto again
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}
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if !errors.Is(err, syscall.EAFNOSUPPORT) {
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unix.Close(sock6)
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return nil, 0, err
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}
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} else {
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port = newPort
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}
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var fns []ReceiveFunc
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if sock4 != -1 {
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fns = append(fns, makeReceiveIPv4(sock4))
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bind.sock4 = sock4
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}
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if sock6 != -1 {
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fns = append(fns, makeReceiveIPv6(sock6))
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bind.sock6 = sock6
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}
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if len(fns) == 0 {
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return nil, 0, syscall.EAFNOSUPPORT
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}
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return fns, port, nil
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}
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func (bind *LinuxSocketBind) SetMark(value uint32) error {
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bind.mu.RLock()
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defer bind.mu.RUnlock()
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if bind.sock6 != -1 {
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err := unix.SetsockoptInt(
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bind.sock6,
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unix.SOL_SOCKET,
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unix.SO_MARK,
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int(value),
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)
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if err != nil {
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return err
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}
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}
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if bind.sock4 != -1 {
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err := unix.SetsockoptInt(
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bind.sock4,
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unix.SOL_SOCKET,
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unix.SO_MARK,
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int(value),
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)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (bind *LinuxSocketBind) Close() error {
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// Take a readlock to shut down the sockets...
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bind.mu.RLock()
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if bind.sock6 != -1 {
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unix.Shutdown(bind.sock6, unix.SHUT_RDWR)
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}
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if bind.sock4 != -1 {
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unix.Shutdown(bind.sock4, unix.SHUT_RDWR)
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}
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bind.mu.RUnlock()
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// ...and a write lock to close the fd.
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// This ensures that no one else is using the fd.
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bind.mu.Lock()
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defer bind.mu.Unlock()
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var err1, err2 error
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if bind.sock6 != -1 {
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err1 = unix.Close(bind.sock6)
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bind.sock6 = -1
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}
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if bind.sock4 != -1 {
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err2 = unix.Close(bind.sock4)
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bind.sock4 = -1
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}
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if err1 != nil {
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return err1
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}
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return err2
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}
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func makeReceiveIPv6(sock int) ReceiveFunc {
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return func(buff []byte) (int, Endpoint, error) {
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var end LinuxSocketEndpoint
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n, err := receive6(sock, buff, &end)
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return n, &end, err
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}
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}
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func makeReceiveIPv4(sock int) ReceiveFunc {
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return func(buff []byte) (int, Endpoint, error) {
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var end LinuxSocketEndpoint
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n, err := receive4(sock, buff, &end)
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return n, &end, err
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}
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}
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func (bind *LinuxSocketBind) Send(buff []byte, end Endpoint) error {
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nend, ok := end.(*LinuxSocketEndpoint)
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if !ok {
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return ErrWrongEndpointType
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}
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bind.mu.RLock()
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defer bind.mu.RUnlock()
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if !nend.isV6 {
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if bind.sock4 == -1 {
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return net.ErrClosed
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}
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return send4(bind.sock4, nend, buff)
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} else {
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if bind.sock6 == -1 {
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return net.ErrClosed
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}
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return send6(bind.sock6, nend, buff)
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}
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}
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func (end *LinuxSocketEndpoint) SrcIP() net.IP {
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if !end.isV6 {
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return net.IPv4(
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end.src4().Src[0],
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end.src4().Src[1],
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end.src4().Src[2],
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end.src4().Src[3],
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)
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} else {
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return end.src6().src[:]
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}
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}
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func (end *LinuxSocketEndpoint) DstIP() net.IP {
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if !end.isV6 {
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return net.IPv4(
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end.dst4().Addr[0],
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end.dst4().Addr[1],
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end.dst4().Addr[2],
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end.dst4().Addr[3],
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)
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} else {
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return end.dst6().Addr[:]
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}
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}
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func (end *LinuxSocketEndpoint) DstToBytes() []byte {
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if !end.isV6 {
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return (*[unsafe.Offsetof(end.dst4().Addr) + unsafe.Sizeof(end.dst4().Addr)]byte)(unsafe.Pointer(end.dst4()))[:]
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} else {
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return (*[unsafe.Offsetof(end.dst6().Addr) + unsafe.Sizeof(end.dst6().Addr)]byte)(unsafe.Pointer(end.dst6()))[:]
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}
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}
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func (end *LinuxSocketEndpoint) SrcToString() string {
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return end.SrcIP().String()
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}
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func (end *LinuxSocketEndpoint) DstToString() string {
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var udpAddr net.UDPAddr
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udpAddr.IP = end.DstIP()
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if !end.isV6 {
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udpAddr.Port = end.dst4().Port
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} else {
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udpAddr.Port = end.dst6().Port
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}
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return udpAddr.String()
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}
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func (end *LinuxSocketEndpoint) ClearDst() {
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for i := range end.dst {
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end.dst[i] = 0
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}
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}
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func (end *LinuxSocketEndpoint) ClearSrc() {
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for i := range end.src {
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end.src[i] = 0
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}
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}
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func zoneToUint32(zone string) (uint32, error) {
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if zone == "" {
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return 0, nil
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}
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if intr, err := net.InterfaceByName(zone); err == nil {
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return uint32(intr.Index), nil
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}
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n, err := strconv.ParseUint(zone, 10, 32)
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return uint32(n), err
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}
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func create4(port uint16) (int, uint16, error) {
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// create socket
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fd, err := unix.Socket(
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unix.AF_INET,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return -1, 0, err
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}
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addr := unix.SockaddrInet4{
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Port: int(port),
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}
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// set sockopts and bind
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if err := func() error {
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if err := unix.SetsockoptInt(
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fd,
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unix.IPPROTO_IP,
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unix.IP_PKTINFO,
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1,
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); err != nil {
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return err
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}
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return unix.Bind(fd, &addr)
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}(); err != nil {
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unix.Close(fd)
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return -1, 0, err
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}
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sa, err := unix.Getsockname(fd)
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if err == nil {
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addr.Port = sa.(*unix.SockaddrInet4).Port
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}
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return fd, uint16(addr.Port), err
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}
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func create6(port uint16) (int, uint16, error) {
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// create socket
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fd, err := unix.Socket(
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unix.AF_INET6,
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unix.SOCK_DGRAM,
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0,
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)
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if err != nil {
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return -1, 0, err
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}
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// set sockopts and bind
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addr := unix.SockaddrInet6{
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Port: int(port),
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}
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if err := func() error {
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if err := unix.SetsockoptInt(
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fd,
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unix.IPPROTO_IPV6,
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unix.IPV6_RECVPKTINFO,
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1,
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); err != nil {
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return err
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}
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if err := unix.SetsockoptInt(
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fd,
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unix.IPPROTO_IPV6,
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unix.IPV6_V6ONLY,
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1,
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); err != nil {
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return err
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}
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return unix.Bind(fd, &addr)
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}(); err != nil {
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unix.Close(fd)
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return -1, 0, err
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}
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sa, err := unix.Getsockname(fd)
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if err == nil {
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addr.Port = sa.(*unix.SockaddrInet6).Port
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}
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return fd, uint16(addr.Port), err
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}
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func send4(sock int, end *LinuxSocketEndpoint, buff []byte) error {
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// construct message header
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cmsg := struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet4Pktinfo
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}{
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unix.Cmsghdr{
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Level: unix.IPPROTO_IP,
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Type: unix.IP_PKTINFO,
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Len: unix.SizeofInet4Pktinfo + unix.SizeofCmsghdr,
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},
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unix.Inet4Pktinfo{
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Spec_dst: end.src4().Src,
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Ifindex: end.src4().Ifindex,
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},
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}
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end.mu.Lock()
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_, err := unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst4(), 0)
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end.mu.Unlock()
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if err == nil {
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return nil
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}
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// clear src and retry
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if err == unix.EINVAL {
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end.ClearSrc()
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cmsg.pktinfo = unix.Inet4Pktinfo{}
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end.mu.Lock()
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_, err = unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst4(), 0)
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end.mu.Unlock()
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}
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return err
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}
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func send6(sock int, end *LinuxSocketEndpoint, buff []byte) error {
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// construct message header
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cmsg := struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet6Pktinfo
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}{
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unix.Cmsghdr{
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Level: unix.IPPROTO_IPV6,
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Type: unix.IPV6_PKTINFO,
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Len: unix.SizeofInet6Pktinfo + unix.SizeofCmsghdr,
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},
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unix.Inet6Pktinfo{
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Addr: end.src6().src,
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Ifindex: end.dst6().ZoneId,
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},
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}
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if cmsg.pktinfo.Addr == [16]byte{} {
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cmsg.pktinfo.Ifindex = 0
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}
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end.mu.Lock()
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_, err := unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst6(), 0)
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end.mu.Unlock()
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if err == nil {
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return nil
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}
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// clear src and retry
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if err == unix.EINVAL {
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end.ClearSrc()
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cmsg.pktinfo = unix.Inet6Pktinfo{}
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end.mu.Lock()
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_, err = unix.SendmsgN(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], end.dst6(), 0)
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end.mu.Unlock()
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}
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return err
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}
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|
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func receive4(sock int, buff []byte, end *LinuxSocketEndpoint) (int, error) {
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|
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// construct message header
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var cmsg struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet4Pktinfo
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}
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size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
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if err != nil {
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return 0, err
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}
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end.isV6 = false
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|
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if newDst4, ok := newDst.(*unix.SockaddrInet4); ok {
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*end.dst4() = *newDst4
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}
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// update source cache
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if cmsg.cmsghdr.Level == unix.IPPROTO_IP &&
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cmsg.cmsghdr.Type == unix.IP_PKTINFO &&
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cmsg.cmsghdr.Len >= unix.SizeofInet4Pktinfo {
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end.src4().Src = cmsg.pktinfo.Spec_dst
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end.src4().Ifindex = cmsg.pktinfo.Ifindex
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}
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return size, nil
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}
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|
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func receive6(sock int, buff []byte, end *LinuxSocketEndpoint) (int, error) {
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|
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// construct message header
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var cmsg struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet6Pktinfo
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}
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size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
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|
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if err != nil {
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return 0, err
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}
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end.isV6 = true
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|
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if newDst6, ok := newDst.(*unix.SockaddrInet6); ok {
|
|
*end.dst6() = *newDst6
|
|
}
|
|
|
|
// update source cache
|
|
|
|
if cmsg.cmsghdr.Level == unix.IPPROTO_IPV6 &&
|
|
cmsg.cmsghdr.Type == unix.IPV6_PKTINFO &&
|
|
cmsg.cmsghdr.Len >= unix.SizeofInet6Pktinfo {
|
|
end.src6().src = cmsg.pktinfo.Addr
|
|
end.dst6().ZoneId = cmsg.pktinfo.Ifindex
|
|
}
|
|
|
|
return size, nil
|
|
}
|