tailscale/net/tcpinfo/tcpinfo_linux.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tcpinfo
import (
"net"
"time"
"golang.org/x/sys/unix"
)
func rttImpl(conn *net.TCPConn) (time.Duration, error) {
rawConn, err := conn.SyscallConn()
if err != nil {
return 0, err
}
var (
tcpInfo *unix.TCPInfo
sysErr error
)
err = rawConn.Control(func(fd uintptr) {
tcpInfo, sysErr = unix.GetsockoptTCPInfo(int(fd), unix.IPPROTO_TCP, unix.TCP_INFO)
})
if err != nil {
return 0, err
} else if sysErr != nil {
return 0, sysErr
}
return time.Duration(tcpInfo.Rtt) * time.Microsecond, nil
}