mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-25 19:15:34 +00:00
318 lines
8.4 KiB
Go
318 lines
8.4 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package main
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import (
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"bytes"
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"context"
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"math"
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"math/rand/v2"
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"net/netip"
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"syscall"
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"time"
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"github.com/mdlayher/socket"
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"golang.org/x/net/icmp"
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"golang.org/x/net/ipv4"
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"golang.org/x/net/ipv6"
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"golang.org/x/sys/unix"
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"tailscale.com/net/stun"
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)
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const (
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timestampingFlags = unix.SOF_TIMESTAMPING_TX_SOFTWARE | // tx timestamp generation in device driver
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unix.SOF_TIMESTAMPING_RX_SOFTWARE | // rx timestamp generation in the kernel
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unix.SOF_TIMESTAMPING_SOFTWARE // report software timestamps
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)
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func getUDPConnKernelTimestamp() (io.ReadWriteCloser, error) {
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sconn, err := socket.Socket(unix.AF_INET6, unix.SOCK_DGRAM, unix.IPPROTO_UDP, "udp", nil)
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if err != nil {
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return nil, err
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}
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sa := unix.SockaddrInet6{}
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err = sconn.Bind(&sa)
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if err != nil {
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return nil, err
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}
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err = sconn.SetsockoptInt(unix.SOL_SOCKET, unix.SO_TIMESTAMPING_NEW, timestampingFlags)
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if err != nil {
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return nil, err
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}
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return sconn, nil
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}
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func parseTimestampFromCmsgs(oob []byte) (time.Time, error) {
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msgs, err := unix.ParseSocketControlMessage(oob)
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if err != nil {
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return time.Time{}, fmt.Errorf("error parsing oob as cmsgs: %w", err)
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}
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for _, msg := range msgs {
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if msg.Header.Level == unix.SOL_SOCKET && msg.Header.Type == unix.SO_TIMESTAMPING_NEW && len(msg.Data) >= 16 {
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sec := int64(binary.NativeEndian.Uint64(msg.Data[:8]))
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ns := int64(binary.NativeEndian.Uint64(msg.Data[8:16]))
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return time.Unix(sec, ns), nil
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}
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}
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return time.Time{}, errors.New("failed to parse timestamp from cmsgs")
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}
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func mkICMPMeasureFn(source timestampSource) measureFn {
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return func(conn io.ReadWriteCloser, hostname string, dst netip.AddrPort) (rtt time.Duration, err error) {
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return measureICMPRTT(source, conn, hostname, dst)
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}
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}
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func measureICMPRTT(source timestampSource, conn io.ReadWriteCloser, _ string, dst netip.AddrPort) (rtt time.Duration, err error) {
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sconn, ok := conn.(*socket.Conn)
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if !ok {
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return 0, fmt.Errorf("conn of unexpected type: %T", conn)
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}
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txBody := &icmp.Echo{
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// The kernel overrides this and routes appropriately so there is no
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// point in setting or verifying.
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ID: 0,
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// Make this sufficiently random so that we do not account a late
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// arriving reply in a future probe window.
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Seq: int(rand.Int32N(math.MaxUint16)),
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// Fingerprint ourselves.
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Data: []byte("stunstamp"),
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}
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txMsg := icmp.Message{
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Body: txBody,
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}
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var to unix.Sockaddr
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if dst.Addr().Is4() {
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txMsg.Type = ipv4.ICMPTypeEcho
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to = &unix.SockaddrInet4{}
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copy(to.(*unix.SockaddrInet4).Addr[:], dst.Addr().AsSlice())
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} else {
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txMsg.Type = ipv6.ICMPTypeEchoRequest
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to = &unix.SockaddrInet6{}
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copy(to.(*unix.SockaddrInet6).Addr[:], dst.Addr().AsSlice())
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}
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txBuf, err := txMsg.Marshal(nil)
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if err != nil {
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return 0, err
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}
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txAt := time.Now()
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err = sconn.Sendto(context.Background(), txBuf, 0, to)
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if err != nil {
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return 0, fmt.Errorf("sendto error: %v", err)
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}
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if source == timestampSourceKernel {
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txCtx, txCancel := context.WithTimeout(context.Background(), txRxTimeout)
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defer txCancel()
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buf := make([]byte, 1024)
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oob := make([]byte, 1024)
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for {
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n, oobn, _, _, err := sconn.Recvmsg(txCtx, buf, oob, unix.MSG_ERRQUEUE)
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if err != nil {
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return 0, fmt.Errorf("recvmsg (MSG_ERRQUEUE) error: %v", err) // don't wrap
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}
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buf = buf[:n]
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// Spin until we find the message we sent. We get the full packet
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// looped including eth header so match against the tail.
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if n < len(txBuf) {
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continue
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}
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txLoopedMsg, err := icmp.ParseMessage(txMsg.Type.Protocol(), buf[len(buf)-len(txBuf):])
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if err != nil {
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continue
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}
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txLoopedBody, ok := txLoopedMsg.Body.(*icmp.Echo)
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if !ok || txLoopedBody.Seq != txBody.Seq || txLoopedMsg.Code != txMsg.Code ||
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txLoopedMsg.Type != txLoopedMsg.Type || !bytes.Equal(txLoopedBody.Data, txBody.Data) {
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continue
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}
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txAt, err = parseTimestampFromCmsgs(oob[:oobn])
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if err != nil {
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return 0, fmt.Errorf("failed to get tx timestamp: %v", err) // don't wrap
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}
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break
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}
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}
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rxCtx, rxCancel := context.WithTimeout(context.Background(), txRxTimeout)
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defer rxCancel()
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rxBuf := make([]byte, 1024)
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oob := make([]byte, 1024)
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for {
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n, oobn, _, _, err := sconn.Recvmsg(rxCtx, rxBuf, oob, 0)
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if err != nil {
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return 0, fmt.Errorf("recvmsg error: %w", err)
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}
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rxAt := time.Now()
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rxMsg, err := icmp.ParseMessage(txMsg.Type.Protocol(), rxBuf[:n])
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if err != nil {
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continue
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}
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if txMsg.Type == ipv4.ICMPTypeEcho {
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if rxMsg.Type != ipv4.ICMPTypeEchoReply {
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continue
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}
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} else {
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if rxMsg.Type != ipv6.ICMPTypeEchoReply {
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continue
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}
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}
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if rxMsg.Code != txMsg.Code {
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continue
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}
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rxBody, ok := rxMsg.Body.(*icmp.Echo)
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if !ok || rxBody.Seq != txBody.Seq || !bytes.Equal(rxBody.Data, txBody.Data) {
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continue
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}
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if source == timestampSourceKernel {
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rxAt, err = parseTimestampFromCmsgs(oob[:oobn])
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if err != nil {
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return 0, fmt.Errorf("failed to get rx timestamp: %v", err)
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}
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}
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return rxAt.Sub(txAt), nil
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}
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}
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func measureSTUNRTTKernel(conn io.ReadWriteCloser, _ string, dst netip.AddrPort) (rtt time.Duration, err error) {
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sconn, ok := conn.(*socket.Conn)
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if !ok {
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return 0, fmt.Errorf("conn of unexpected type: %T", conn)
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}
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var to unix.Sockaddr
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if dst.Addr().Is4() {
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to = &unix.SockaddrInet4{
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Port: int(dst.Port()),
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}
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copy(to.(*unix.SockaddrInet4).Addr[:], dst.Addr().AsSlice())
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} else {
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to = &unix.SockaddrInet6{
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Port: int(dst.Port()),
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}
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copy(to.(*unix.SockaddrInet6).Addr[:], dst.Addr().AsSlice())
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}
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txID := stun.NewTxID()
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req := stun.Request(txID)
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err = sconn.Sendto(context.Background(), req, 0, to)
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if err != nil {
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return 0, fmt.Errorf("sendto error: %v", err) // don't wrap
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}
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txCtx, txCancel := context.WithTimeout(context.Background(), txRxTimeout)
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defer txCancel()
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buf := make([]byte, 1024)
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oob := make([]byte, 1024)
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var txAt time.Time
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for {
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n, oobn, _, _, err := sconn.Recvmsg(txCtx, buf, oob, unix.MSG_ERRQUEUE)
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if err != nil {
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return 0, fmt.Errorf("recvmsg (MSG_ERRQUEUE) error: %v", err) // don't wrap
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}
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buf = buf[:n]
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if n < len(req) || !bytes.Equal(req, buf[len(buf)-len(req):]) {
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// Spin until we find the message we sent. We get the full packet
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// looped including eth header so match against the tail.
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continue
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}
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txAt, err = parseTimestampFromCmsgs(oob[:oobn])
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if err != nil {
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return 0, fmt.Errorf("failed to get tx timestamp: %v", err) // don't wrap
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}
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break
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}
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rxCtx, rxCancel := context.WithTimeout(context.Background(), txRxTimeout)
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defer rxCancel()
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for {
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n, oobn, _, _, err := sconn.Recvmsg(rxCtx, buf, oob, 0)
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if err != nil {
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return 0, fmt.Errorf("recvmsg error: %w", err) // wrap for timeout-related error unwrapping
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}
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gotTxID, _, err := stun.ParseResponse(buf[:n])
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if err != nil || gotTxID != txID {
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// Spin until we find the txID we sent. We may end up reading
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// extremely late arriving responses from previous intervals. As
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// such, we can't be certain if we're parsing the "current"
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// response, so spin for parse errors too.
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continue
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}
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rxAt, err := parseTimestampFromCmsgs(oob[:oobn])
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if err != nil {
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return 0, fmt.Errorf("failed to get rx timestamp: %v", err) // don't wrap
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}
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return rxAt.Sub(txAt), nil
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}
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}
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func getICMPConn(forDst netip.Addr, source timestampSource) (io.ReadWriteCloser, error) {
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domain := unix.AF_INET
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proto := unix.IPPROTO_ICMP
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if forDst.Is6() {
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domain = unix.AF_INET6
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proto = unix.IPPROTO_ICMPV6
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}
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conn, err := socket.Socket(domain, unix.SOCK_DGRAM, proto, "icmp", nil)
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if err != nil {
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return nil, err
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}
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if source == timestampSourceKernel {
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err = conn.SetsockoptInt(unix.SOL_SOCKET, unix.SO_TIMESTAMPING_NEW, timestampingFlags)
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}
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return conn, err
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}
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func getProtocolSupportInfo(p protocol) protocolSupportInfo {
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switch p {
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case protocolSTUN:
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return protocolSupportInfo{
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kernelTS: true,
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userspaceTS: true,
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stableConn: true,
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}
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case protocolHTTPS:
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return protocolSupportInfo{
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kernelTS: false,
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userspaceTS: true,
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stableConn: true,
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}
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case protocolTCP:
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return protocolSupportInfo{
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kernelTS: true,
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userspaceTS: false,
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stableConn: true,
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}
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case protocolICMP:
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return protocolSupportInfo{
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kernelTS: true,
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userspaceTS: true,
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stableConn: false,
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}
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}
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return protocolSupportInfo{}
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}
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func setSOReuseAddr(fd uintptr) error {
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// we may restart faster than TIME_WAIT can clear
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return syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1)
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}
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