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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux
package net
import (
"internal/poll"
"io"
"os"
"strconv"
"sync"
"syscall"
"testing"
)
func TestSplice(t *testing.T) {
t.Run("tcp-to-tcp", func(t *testing.T) { testSplice(t, "tcp", "tcp") })
if !testableNetwork("unixgram") {
t.Skip("skipping unix-to-tcp tests")
}
t.Run("unix-to-tcp", func(t *testing.T) { testSplice(t, "unix", "tcp") })
t.Run("tcp-to-unix", func(t *testing.T) { testSplice(t, "tcp", "unix") })
t.Run("tcp-to-file", func(t *testing.T) { testSpliceToFile(t, "tcp", "file") })
t.Run("unix-to-file", func(t *testing.T) { testSpliceToFile(t, "unix", "file") })
t.Run("no-unixpacket", testSpliceNoUnixpacket)
t.Run("no-unixgram", testSpliceNoUnixgram)
}
func testSpliceToFile(t *testing.T, upNet, downNet string) {
t.Run("simple", spliceTestCase{upNet, downNet, 128, 128, 0}.testFile)
t.Run("multipleWrite", spliceTestCase{upNet, downNet, 4096, 1 << 20, 0}.testFile)
t.Run("big", spliceTestCase{upNet, downNet, 5 << 20, 1 << 30, 0}.testFile)
t.Run("honorsLimitedReader", spliceTestCase{upNet, downNet, 4096, 1 << 20, 1 << 10}.testFile)
t.Run("updatesLimitedReaderN", spliceTestCase{upNet, downNet, 1024, 4096, 4096 + 100}.testFile)
t.Run("limitedReaderAtLimit", spliceTestCase{upNet, downNet, 32, 128, 128}.testFile)
}
func testSplice(t *testing.T, upNet, downNet string) {
t.Run("simple", spliceTestCase{upNet, downNet, 128, 128, 0}.test)
t.Run("multipleWrite", spliceTestCase{upNet, downNet, 4096, 1 << 20, 0}.test)
t.Run("big", spliceTestCase{upNet, downNet, 5 << 20, 1 << 30, 0}.test)
t.Run("honorsLimitedReader", spliceTestCase{upNet, downNet, 4096, 1 << 20, 1 << 10}.test)
t.Run("updatesLimitedReaderN", spliceTestCase{upNet, downNet, 1024, 4096, 4096 + 100}.test)
t.Run("limitedReaderAtLimit", spliceTestCase{upNet, downNet, 32, 128, 128}.test)
t.Run("readerAtEOF", func(t *testing.T) { testSpliceReaderAtEOF(t, upNet, downNet) })
t.Run("issue25985", func(t *testing.T) { testSpliceIssue25985(t, upNet, downNet) })
}
type spliceTestCase struct {
upNet, downNet string
chunkSize, totalSize int
limitReadSize int
}
func (tc spliceTestCase) test(t *testing.T) {
hook := hookSplice(t)
// We need to use the actual size for startTestSocketPeer when testing with LimitedReader,
// otherwise the child process created in startTestSocketPeer will hang infinitely because of
// the mismatch of data size to transfer.
size := tc.totalSize
if tc.limitReadSize > 0 {
if tc.limitReadSize < size {
size = tc.limitReadSize
}
}
clientUp, serverUp := spawnTestSocketPair(t, tc.upNet)
defer serverUp.Close()
cleanup, err := startTestSocketPeer(t, clientUp, "w", tc.chunkSize, size)
if err != nil {
t.Fatal(err)
}
defer cleanup(t)
clientDown, serverDown := spawnTestSocketPair(t, tc.downNet)
defer serverDown.Close()
cleanup, err = startTestSocketPeer(t, clientDown, "r", tc.chunkSize, size)
if err != nil {
t.Fatal(err)
}
defer cleanup(t)
var r io.Reader = serverUp
if tc.limitReadSize > 0 {
r = &io.LimitedReader{
N: int64(tc.limitReadSize),
R: serverUp,
}
defer serverUp.Close()
}
n, err := io.Copy(serverDown, r)
if err != nil {
t.Fatal(err)
}
if want := int64(size); want != n {
t.Errorf("want %d bytes spliced, got %d", want, n)
}
if tc.limitReadSize > 0 {
wantN := 0
if tc.limitReadSize > size {
wantN = tc.limitReadSize - size
}
if n := r.(*io.LimitedReader).N; n != int64(wantN) {
t.Errorf("r.N = %d, want %d", n, wantN)
}
}
// poll.Splice is expected to be called when the source is not
// a wrapper or the destination is TCPConn.
if tc.limitReadSize == 0 || tc.downNet == "tcp" {
// We should have called poll.Splice with the right file descriptor arguments.
if n > 0 && !hook.called {
t.Fatal("expected poll.Splice to be called")
}
verifySpliceFds(t, serverDown, hook, "dst")
verifySpliceFds(t, serverUp, hook, "src")
// poll.Splice is expected to handle the data transmission successfully.
if !hook.handled || hook.written != int64(size) || hook.err != nil {
t.Errorf("expected handled = true, written = %d, err = nil, but got handled = %t, written = %d, err = %v",
size, hook.handled, hook.written, hook.err)
}
} else if hook.called {
// poll.Splice will certainly not be called when the source
// is a wrapper and the destination is not TCPConn.
t.Errorf("expected poll.Splice not be called")
}
}
func verifySpliceFds(t *testing.T, c Conn, hook *spliceHook, fdType string) {
t.Helper()
sc, ok := c.(syscall.Conn)
if !ok {
t.Fatalf("expected syscall.Conn")
}
rc, err := sc.SyscallConn()
if err != nil {
t.Fatalf("syscall.Conn.SyscallConn error: %v", err)
}
var hookFd int
switch fdType {
case "src":
hookFd = hook.srcfd
case "dst":
hookFd = hook.dstfd
default:
t.Fatalf("unknown fdType %q", fdType)
}
if err := rc.Control(func(fd uintptr) {
if hook.called && hookFd != int(fd) {
t.Fatalf("wrong %s file descriptor: got %d, want %d", fdType, hook.dstfd, int(fd))
}
}); err != nil {
t.Fatalf("syscall.RawConn.Control error: %v", err)
}
}
func (tc spliceTestCase) testFile(t *testing.T) {
hook := hookSplice(t)
// We need to use the actual size for startTestSocketPeer when testing with LimitedReader,
// otherwise the child process created in startTestSocketPeer will hang infinitely because of
// the mismatch of data size to transfer.
actualSize := tc.totalSize
if tc.limitReadSize > 0 {
if tc.limitReadSize < actualSize {
actualSize = tc.limitReadSize
}
}
f, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
if err != nil {
t.Fatal(err)
}
defer f.Close()
client, server := spawnTestSocketPair(t, tc.upNet)
defer server.Close()
cleanup, err := startTestSocketPeer(t, client, "w", tc.chunkSize, actualSize)
if err != nil {
client.Close()
t.Fatal("failed to start splice client:", err)
}
defer cleanup(t)
var r io.Reader = server
if tc.limitReadSize > 0 {
r = &io.LimitedReader{
N: int64(tc.limitReadSize),
R: r,
}
}
got, err := io.Copy(f, r)
if err != nil {
t.Fatalf("failed to ReadFrom with error: %v", err)
}
// We shouldn't have called poll.Splice in TCPConn.WriteTo,
// it's supposed to be called from File.ReadFrom.
if got > 0 && hook.called {
t.Error("expected not poll.Splice to be called")
}
if want := int64(actualSize); got != want {
t.Errorf("got %d bytes, want %d", got, want)
}
if tc.limitReadSize > 0 {
wantN := 0
if tc.limitReadSize > actualSize {
wantN = tc.limitReadSize - actualSize
}
if gotN := r.(*io.LimitedReader).N; gotN != int64(wantN) {
t.Errorf("r.N = %d, want %d", gotN, wantN)
}
}
}
func testSpliceReaderAtEOF(t *testing.T, upNet, downNet string) {
// UnixConn doesn't implement io.ReaderFrom, which will fail
// the following test in asserting a UnixConn to be an io.ReaderFrom,
// so skip this test.
if downNet == "unix" {
t.Skip("skipping test on unix socket")
}
hook := hookSplice(t)
clientUp, serverUp := spawnTestSocketPair(t, upNet)
defer clientUp.Close()
clientDown, serverDown := spawnTestSocketPair(t, downNet)
defer clientDown.Close()
defer serverDown.Close()
serverUp.Close()
// We'd like to call net.spliceFrom here and check the handled return
// value, but we disable splice on old Linux kernels.
//
// In that case, poll.Splice and net.spliceFrom return a non-nil error
// and handled == false. We'd ideally like to see handled == true
// because the source reader is at EOF, but if we're running on an old
// kernel, and splice is disabled, we won't see EOF from net.spliceFrom,
// because we won't touch the reader at all.
//
// Trying to untangle the errors from net.spliceFrom and match them
// against the errors created by the poll package would be brittle,
// so this is a higher level test.
//
// The following ReadFrom should return immediately, regardless of
// whether splice is disabled or not. The other side should then
// get a goodbye signal. Test for the goodbye signal.
msg := "bye"
go func() {
serverDown.(io.ReaderFrom).ReadFrom(serverUp)
io.WriteString(serverDown, msg)
}()
buf := make([]byte, 3)
n, err := io.ReadFull(clientDown, buf)
if err != nil {
t.Errorf("clientDown: %v", err)
}
if string(buf) != msg {
t.Errorf("clientDown got %q, want %q", buf, msg)
}
// We should have called poll.Splice with the right file descriptor arguments.
if n > 0 && !hook.called {
t.Fatal("expected poll.Splice to be called")
}
verifySpliceFds(t, serverDown, hook, "dst")
// poll.Splice is expected to handle the data transmission but fail
// when working with a closed endpoint, return an error.
if !hook.handled || hook.written > 0 || hook.err == nil {
t.Errorf("expected handled = true, written = 0, err != nil, but got handled = %t, written = %d, err = %v",
hook.handled, hook.written, hook.err)
}
}
func testSpliceIssue25985(t *testing.T, upNet, downNet string) {
front := newLocalListener(t, upNet)
defer front.Close()
back := newLocalListener(t, downNet)
defer back.Close()
var wg sync.WaitGroup
wg.Add(2)
proxy := func() {
src, err := front.Accept()
if err != nil {
return
}
dst, err := Dial(downNet, back.Addr().String())
if err != nil {
return
}
defer dst.Close()
defer src.Close()
go func() {
io.Copy(src, dst)
wg.Done()
}()
go func() {
io.Copy(dst, src)
wg.Done()
}()
}
go proxy()
toFront, err := Dial(upNet, front.Addr().String())
if err != nil {
t.Fatal(err)
}
io.WriteString(toFront, "foo")
toFront.Close()
fromProxy, err := back.Accept()
if err != nil {
t.Fatal(err)
}
defer fromProxy.Close()
_, err = io.ReadAll(fromProxy)
if err != nil {
t.Fatal(err)
}
wg.Wait()
}
func testSpliceNoUnixpacket(t *testing.T) {
clientUp, serverUp := spawnTestSocketPair(t, "unixpacket")
defer clientUp.Close()
defer serverUp.Close()
clientDown, serverDown := spawnTestSocketPair(t, "tcp")
defer clientDown.Close()
defer serverDown.Close()
// If splice called poll.Splice here, we'd get err == syscall.EINVAL
// and handled == false. If poll.Splice gets an EINVAL on the first
// try, it assumes the kernel it's running on doesn't support splice
// for unix sockets and returns handled == false. This works for our
// purposes by somewhat of an accident, but is not entirely correct.
//
// What we want is err == nil and handled == false, i.e. we never
// called poll.Splice, because we know the unix socket's network.
_, err, handled := spliceFrom(serverDown.(*TCPConn).fd, serverUp)
if err != nil || handled != false {
t.Fatalf("got err = %v, handled = %t, want nil error, handled == false", err, handled)
}
}
func testSpliceNoUnixgram(t *testing.T) {
addr, err := ResolveUnixAddr("unixgram", testUnixAddr(t))
if err != nil {
t.Fatal(err)
}
defer os.Remove(addr.Name)
up, err := ListenUnixgram("unixgram", addr)
if err != nil {
t.Fatal(err)
}
defer up.Close()
clientDown, serverDown := spawnTestSocketPair(t, "tcp")
defer clientDown.Close()
defer serverDown.Close()
// Analogous to testSpliceNoUnixpacket.
_, err, handled := spliceFrom(serverDown.(*TCPConn).fd, up)
if err != nil || handled != false {
t.Fatalf("got err = %v, handled = %t, want nil error, handled == false", err, handled)
}
}
func BenchmarkSplice(b *testing.B) {
testHookUninstaller.Do(uninstallTestHooks)
b.Run("tcp-to-tcp", func(b *testing.B) { benchSplice(b, "tcp", "tcp") })
b.Run("unix-to-tcp", func(b *testing.B) { benchSplice(b, "unix", "tcp") })
b.Run("tcp-to-unix", func(b *testing.B) { benchSplice(b, "tcp", "unix") })
}
func benchSplice(b *testing.B, upNet, downNet string) {
for i := 0; i <= 10; i++ {
chunkSize := 1 << uint(i+10)
tc := spliceTestCase{
upNet: upNet,
downNet: downNet,
chunkSize: chunkSize,
}
b.Run(strconv.Itoa(chunkSize), tc.bench)
}
}
func (tc spliceTestCase) bench(b *testing.B) {
// To benchmark the genericReadFrom code path, set this to false.
useSplice := true
clientUp, serverUp := spawnTestSocketPair(b, tc.upNet)
defer serverUp.Close()
cleanup, err := startTestSocketPeer(b, clientUp, "w", tc.chunkSize, tc.chunkSize*b.N)
if err != nil {
b.Fatal(err)
}
defer cleanup(b)
clientDown, serverDown := spawnTestSocketPair(b, tc.downNet)
defer serverDown.Close()
cleanup, err = startTestSocketPeer(b, clientDown, "r", tc.chunkSize, tc.chunkSize*b.N)
if err != nil {
b.Fatal(err)
}
defer cleanup(b)
b.SetBytes(int64(tc.chunkSize))
b.ResetTimer()
if useSplice {
_, err := io.Copy(serverDown, serverUp)
if err != nil {
b.Fatal(err)
}
} else {
type onlyReader struct {
io.Reader
}
_, err := io.Copy(serverDown, onlyReader{serverUp})
if err != nil {
b.Fatal(err)
}
}
}
func BenchmarkSpliceFile(b *testing.B) {
b.Run("tcp-to-file", func(b *testing.B) { benchmarkSpliceFile(b, "tcp") })
b.Run("unix-to-file", func(b *testing.B) { benchmarkSpliceFile(b, "unix") })
}
func benchmarkSpliceFile(b *testing.B, proto string) {
for i := 0; i <= 10; i++ {
size := 1 << (i + 10)
bench := spliceFileBench{
proto: proto,
chunkSize: size,
}
b.Run(strconv.Itoa(size), bench.benchSpliceFile)
}
}
type spliceFileBench struct {
proto string
chunkSize int
}
func (bench spliceFileBench) benchSpliceFile(b *testing.B) {
f, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
if err != nil {
b.Fatal(err)
}
defer f.Close()
totalSize := b.N * bench.chunkSize
client, server := spawnTestSocketPair(b, bench.proto)
defer server.Close()
cleanup, err := startTestSocketPeer(b, client, "w", bench.chunkSize, totalSize)
if err != nil {
client.Close()
b.Fatalf("failed to start splice client: %v", err)
}
defer cleanup(b)
b.ReportAllocs()
b.SetBytes(int64(bench.chunkSize))
b.ResetTimer()
got, err := io.Copy(f, server)
if err != nil {
b.Fatalf("failed to ReadFrom with error: %v", err)
}
if want := int64(totalSize); got != want {
b.Errorf("bytes sent mismatch, got: %d, want: %d", got, want)
}
}
func hookSplice(t *testing.T) *spliceHook {
t.Helper()
h := new(spliceHook)
h.install()
t.Cleanup(h.uninstall)
return h
}
type spliceHook struct {
called bool
dstfd int
srcfd int
remain int64
written int64
handled bool
sc string
err error
original func(dst, src *poll.FD, remain int64) (int64, bool, string, error)
}
func (h *spliceHook) install() {
h.original = pollSplice
pollSplice = func(dst, src *poll.FD, remain int64) (int64, bool, string, error) {
h.called = true
h.dstfd = dst.Sysfd
h.srcfd = src.Sysfd
h.remain = remain
h.written, h.handled, h.sc, h.err = h.original(dst, src, remain)
return h.written, h.handled, h.sc, h.err
}
}
func (h *spliceHook) uninstall() {
pollSplice = h.original
}