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tailscale/net/tcpinfo/tcpinfo_test.go

65 lines
1.1 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tcpinfo
import (
"bytes"
"io"
"net"
"runtime"
"testing"
)
func TestRTT(t *testing.T) {
switch runtime.GOOS {
case "linux", "darwin":
default:
t.Skipf("not currently supported on %s", runtime.GOOS)
}
ln, err := net.Listen("tcp4", "localhost:0")
if err != nil {
t.Fatal(err)
}
defer ln.Close()
go func() {
for {
c, err := ln.Accept()
if err != nil {
return
}
t.Cleanup(func() { c.Close() })
// Copy from the client to nowhere
go io.Copy(io.Discard, c)
}
}()
conn, err := net.Dial("tcp4", ln.Addr().String())
if err != nil {
t.Fatal(err)
}
// Write a bunch of data to the conn to force TCP session establishment
// and a few packets.
junkData := bytes.Repeat([]byte("hello world\n"), 1024*1024)
for i := 0; i < 10; i++ {
if _, err := conn.Write(junkData); err != nil {
t.Fatalf("error writing junk data [%d]: %v", i, err)
}
}
// Get the RTT now
rtt, err := RTT(conn)
if err != nil {
t.Fatalf("error getting RTT: %v", err)
}
if rtt == 0 {
t.Errorf("expected RTT > 0")
}
t.Logf("TCP rtt: %v", rtt)
}