tailscale/derp/derp_server_linux.go

96 lines
1.9 KiB
Go

// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package derp
import (
"context"
"crypto/tls"
"net"
"time"
"golang.org/x/sys/unix"
)
func (c *sclient) statsLoop(ctx context.Context) error {
// If we can't get a TCP socket, then we can't send stats.
tcpConn := c.tcpConn()
if tcpConn == nil {
c.s.tcpRtt.Add("non-tcp", 1)
return nil
}
rawConn, err := tcpConn.SyscallConn()
if err != nil {
c.logf("error getting SyscallConn: %v", err)
c.s.tcpRtt.Add("error", 1)
return nil
}
const statsInterval = 10 * time.Second
ticker := time.NewTicker(statsInterval)
defer ticker.Stop()
var (
tcpInfo *unix.TCPInfo
sysErr error
)
statsLoop:
for {
select {
case <-ticker.C:
err = rawConn.Control(func(fd uintptr) {
tcpInfo, sysErr = unix.GetsockoptTCPInfo(int(fd), unix.IPPROTO_TCP, unix.TCP_INFO)
})
if err != nil || sysErr != nil {
continue statsLoop
}
// TODO(andrew): more metrics?
rtt := time.Duration(tcpInfo.Rtt) * time.Microsecond
c.s.tcpRtt.Add(durationToLabel(rtt), 1)
case <-ctx.Done():
return ctx.Err()
}
}
}
// tcpConn attempts to get the underlying *net.TCPConn from this client's
// Conn; if it cannot, then it will return nil.
func (c *sclient) tcpConn() *net.TCPConn {
nc := c.nc
for {
switch v := nc.(type) {
case *net.TCPConn:
return v
case *tls.Conn:
nc = v.NetConn()
default:
return nil
}
}
}
func durationToLabel(dur time.Duration) string {
switch {
case dur <= 10*time.Millisecond:
return "10ms"
case dur <= 20*time.Millisecond:
return "20ms"
case dur <= 50*time.Millisecond:
return "50ms"
case dur <= 100*time.Millisecond:
return "100ms"
case dur <= 150*time.Millisecond:
return "150ms"
case dur <= 250*time.Millisecond:
return "250ms"
case dur <= 500*time.Millisecond:
return "500ms"
default:
return "inf"
}
}