github.com/gocuntian/go@v0.0.0-20160610041250-fee02d270bf8/src/crypto/tls/tls_test.go (about)

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package tls
     6  
     7  import (
     8  	"bytes"
     9  	"errors"
    10  	"fmt"
    11  	"internal/testenv"
    12  	"io"
    13  	"math"
    14  	"net"
    15  	"strings"
    16  	"testing"
    17  	"time"
    18  )
    19  
    20  var rsaCertPEM = `-----BEGIN CERTIFICATE-----
    21  MIIB0zCCAX2gAwIBAgIJAI/M7BYjwB+uMA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNV
    22  BAYTAkFVMRMwEQYDVQQIDApTb21lLVN0YXRlMSEwHwYDVQQKDBhJbnRlcm5ldCBX
    23  aWRnaXRzIFB0eSBMdGQwHhcNMTIwOTEyMjE1MjAyWhcNMTUwOTEyMjE1MjAyWjBF
    24  MQswCQYDVQQGEwJBVTETMBEGA1UECAwKU29tZS1TdGF0ZTEhMB8GA1UECgwYSW50
    25  ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANLJ
    26  hPHhITqQbPklG3ibCVxwGMRfp/v4XqhfdQHdcVfHap6NQ5Wok/4xIA+ui35/MmNa
    27  rtNuC+BdZ1tMuVCPFZcCAwEAAaNQME4wHQYDVR0OBBYEFJvKs8RfJaXTH08W+SGv
    28  zQyKn0H8MB8GA1UdIwQYMBaAFJvKs8RfJaXTH08W+SGvzQyKn0H8MAwGA1UdEwQF
    29  MAMBAf8wDQYJKoZIhvcNAQEFBQADQQBJlffJHybjDGxRMqaRmDhX0+6v02TUKZsW
    30  r5QuVbpQhH6u+0UgcW0jp9QwpxoPTLTWGXEWBBBurxFwiCBhkQ+V
    31  -----END CERTIFICATE-----
    32  `
    33  
    34  var rsaKeyPEM = `-----BEGIN RSA PRIVATE KEY-----
    35  MIIBOwIBAAJBANLJhPHhITqQbPklG3ibCVxwGMRfp/v4XqhfdQHdcVfHap6NQ5Wo
    36  k/4xIA+ui35/MmNartNuC+BdZ1tMuVCPFZcCAwEAAQJAEJ2N+zsR0Xn8/Q6twa4G
    37  6OB1M1WO+k+ztnX/1SvNeWu8D6GImtupLTYgjZcHufykj09jiHmjHx8u8ZZB/o1N
    38  MQIhAPW+eyZo7ay3lMz1V01WVjNKK9QSn1MJlb06h/LuYv9FAiEA25WPedKgVyCW
    39  SmUwbPw8fnTcpqDWE3yTO3vKcebqMSsCIBF3UmVue8YU3jybC3NxuXq3wNm34R8T
    40  xVLHwDXh/6NJAiEAl2oHGGLz64BuAfjKrqwz7qMYr9HCLIe/YsoWq/olzScCIQDi
    41  D2lWusoe2/nEqfDVVWGWlyJ7yOmqaVm/iNUN9B2N2g==
    42  -----END RSA PRIVATE KEY-----
    43  `
    44  
    45  // keyPEM is the same as rsaKeyPEM, but declares itself as just
    46  // "PRIVATE KEY", not "RSA PRIVATE KEY".  https://golang.org/issue/4477
    47  var keyPEM = `-----BEGIN PRIVATE KEY-----
    48  MIIBOwIBAAJBANLJhPHhITqQbPklG3ibCVxwGMRfp/v4XqhfdQHdcVfHap6NQ5Wo
    49  k/4xIA+ui35/MmNartNuC+BdZ1tMuVCPFZcCAwEAAQJAEJ2N+zsR0Xn8/Q6twa4G
    50  6OB1M1WO+k+ztnX/1SvNeWu8D6GImtupLTYgjZcHufykj09jiHmjHx8u8ZZB/o1N
    51  MQIhAPW+eyZo7ay3lMz1V01WVjNKK9QSn1MJlb06h/LuYv9FAiEA25WPedKgVyCW
    52  SmUwbPw8fnTcpqDWE3yTO3vKcebqMSsCIBF3UmVue8YU3jybC3NxuXq3wNm34R8T
    53  xVLHwDXh/6NJAiEAl2oHGGLz64BuAfjKrqwz7qMYr9HCLIe/YsoWq/olzScCIQDi
    54  D2lWusoe2/nEqfDVVWGWlyJ7yOmqaVm/iNUN9B2N2g==
    55  -----END PRIVATE KEY-----
    56  `
    57  
    58  var ecdsaCertPEM = `-----BEGIN CERTIFICATE-----
    59  MIIB/jCCAWICCQDscdUxw16XFDAJBgcqhkjOPQQBMEUxCzAJBgNVBAYTAkFVMRMw
    60  EQYDVQQIEwpTb21lLVN0YXRlMSEwHwYDVQQKExhJbnRlcm5ldCBXaWRnaXRzIFB0
    61  eSBMdGQwHhcNMTIxMTE0MTI0MDQ4WhcNMTUxMTE0MTI0MDQ4WjBFMQswCQYDVQQG
    62  EwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEhMB8GA1UEChMYSW50ZXJuZXQgV2lk
    63  Z2l0cyBQdHkgTHRkMIGbMBAGByqGSM49AgEGBSuBBAAjA4GGAAQBY9+my9OoeSUR
    64  lDQdV/x8LsOuLilthhiS1Tz4aGDHIPwC1mlvnf7fg5lecYpMCrLLhauAc1UJXcgl
    65  01xoLuzgtAEAgv2P/jgytzRSpUYvgLBt1UA0leLYBy6mQQbrNEuqT3INapKIcUv8
    66  XxYP0xMEUksLPq6Ca+CRSqTtrd/23uTnapkwCQYHKoZIzj0EAQOBigAwgYYCQXJo
    67  A7Sl2nLVf+4Iu/tAX/IF4MavARKC4PPHK3zfuGfPR3oCCcsAoz3kAzOeijvd0iXb
    68  H5jBImIxPL4WxQNiBTexAkF8D1EtpYuWdlVQ80/h/f4pBcGiXPqX5h2PQSQY7hP1
    69  +jwM1FGS4fREIOvlBYr/SzzQRtwrvrzGYxDEDbsC0ZGRnA==
    70  -----END CERTIFICATE-----
    71  `
    72  
    73  var ecdsaKeyPEM = `-----BEGIN EC PARAMETERS-----
    74  BgUrgQQAIw==
    75  -----END EC PARAMETERS-----
    76  -----BEGIN EC PRIVATE KEY-----
    77  MIHcAgEBBEIBrsoKp0oqcv6/JovJJDoDVSGWdirrkgCWxrprGlzB9o0X8fV675X0
    78  NwuBenXFfeZvVcwluO7/Q9wkYoPd/t3jGImgBwYFK4EEACOhgYkDgYYABAFj36bL
    79  06h5JRGUNB1X/Hwuw64uKW2GGJLVPPhoYMcg/ALWaW+d/t+DmV5xikwKssuFq4Bz
    80  VQldyCXTXGgu7OC0AQCC/Y/+ODK3NFKlRi+AsG3VQDSV4tgHLqZBBus0S6pPcg1q
    81  kohxS/xfFg/TEwRSSws+roJr4JFKpO2t3/be5OdqmQ==
    82  -----END EC PRIVATE KEY-----
    83  `
    84  
    85  var keyPairTests = []struct {
    86  	algo string
    87  	cert string
    88  	key  string
    89  }{
    90  	{"ECDSA", ecdsaCertPEM, ecdsaKeyPEM},
    91  	{"RSA", rsaCertPEM, rsaKeyPEM},
    92  	{"RSA-untyped", rsaCertPEM, keyPEM}, // golang.org/issue/4477
    93  }
    94  
    95  func TestX509KeyPair(t *testing.T) {
    96  	var pem []byte
    97  	for _, test := range keyPairTests {
    98  		pem = []byte(test.cert + test.key)
    99  		if _, err := X509KeyPair(pem, pem); err != nil {
   100  			t.Errorf("Failed to load %s cert followed by %s key: %s", test.algo, test.algo, err)
   101  		}
   102  		pem = []byte(test.key + test.cert)
   103  		if _, err := X509KeyPair(pem, pem); err != nil {
   104  			t.Errorf("Failed to load %s key followed by %s cert: %s", test.algo, test.algo, err)
   105  		}
   106  	}
   107  }
   108  
   109  func TestX509KeyPairErrors(t *testing.T) {
   110  	_, err := X509KeyPair([]byte(rsaKeyPEM), []byte(rsaCertPEM))
   111  	if err == nil {
   112  		t.Fatalf("X509KeyPair didn't return an error when arguments were switched")
   113  	}
   114  	if subStr := "been switched"; !strings.Contains(err.Error(), subStr) {
   115  		t.Fatalf("Expected %q in the error when switching arguments to X509KeyPair, but the error was %q", subStr, err)
   116  	}
   117  
   118  	_, err = X509KeyPair([]byte(rsaCertPEM), []byte(rsaCertPEM))
   119  	if err == nil {
   120  		t.Fatalf("X509KeyPair didn't return an error when both arguments were certificates")
   121  	}
   122  	if subStr := "certificate"; !strings.Contains(err.Error(), subStr) {
   123  		t.Fatalf("Expected %q in the error when both arguments to X509KeyPair were certificates, but the error was %q", subStr, err)
   124  	}
   125  
   126  	const nonsensePEM = `
   127  -----BEGIN NONSENSE-----
   128  Zm9vZm9vZm9v
   129  -----END NONSENSE-----
   130  `
   131  
   132  	_, err = X509KeyPair([]byte(nonsensePEM), []byte(nonsensePEM))
   133  	if err == nil {
   134  		t.Fatalf("X509KeyPair didn't return an error when both arguments were nonsense")
   135  	}
   136  	if subStr := "NONSENSE"; !strings.Contains(err.Error(), subStr) {
   137  		t.Fatalf("Expected %q in the error when both arguments to X509KeyPair were nonsense, but the error was %q", subStr, err)
   138  	}
   139  }
   140  
   141  func TestX509MixedKeyPair(t *testing.T) {
   142  	if _, err := X509KeyPair([]byte(rsaCertPEM), []byte(ecdsaKeyPEM)); err == nil {
   143  		t.Error("Load of RSA certificate succeeded with ECDSA private key")
   144  	}
   145  	if _, err := X509KeyPair([]byte(ecdsaCertPEM), []byte(rsaKeyPEM)); err == nil {
   146  		t.Error("Load of ECDSA certificate succeeded with RSA private key")
   147  	}
   148  }
   149  
   150  func newLocalListener(t testing.TB) net.Listener {
   151  	ln, err := net.Listen("tcp", "127.0.0.1:0")
   152  	if err != nil {
   153  		ln, err = net.Listen("tcp6", "[::1]:0")
   154  	}
   155  	if err != nil {
   156  		t.Fatal(err)
   157  	}
   158  	return ln
   159  }
   160  
   161  func TestDialTimeout(t *testing.T) {
   162  	if testing.Short() {
   163  		t.Skip("skipping in short mode")
   164  	}
   165  	listener := newLocalListener(t)
   166  
   167  	addr := listener.Addr().String()
   168  	defer listener.Close()
   169  
   170  	complete := make(chan bool)
   171  	defer close(complete)
   172  
   173  	go func() {
   174  		conn, err := listener.Accept()
   175  		if err != nil {
   176  			t.Error(err)
   177  			return
   178  		}
   179  		<-complete
   180  		conn.Close()
   181  	}()
   182  
   183  	dialer := &net.Dialer{
   184  		Timeout: 10 * time.Millisecond,
   185  	}
   186  
   187  	var err error
   188  	if _, err = DialWithDialer(dialer, "tcp", addr, nil); err == nil {
   189  		t.Fatal("DialWithTimeout completed successfully")
   190  	}
   191  
   192  	if !isTimeoutError(err) {
   193  		t.Errorf("resulting error not a timeout: %v\nType %T: %#v", err, err, err)
   194  	}
   195  }
   196  
   197  func isTimeoutError(err error) bool {
   198  	if ne, ok := err.(net.Error); ok {
   199  		return ne.Timeout()
   200  	}
   201  	return false
   202  }
   203  
   204  // tests that Conn.Read returns (non-zero, io.EOF) instead of
   205  // (non-zero, nil) when a Close (alertCloseNotify) is sitting right
   206  // behind the application data in the buffer.
   207  func TestConnReadNonzeroAndEOF(t *testing.T) {
   208  	// This test is racy: it assumes that after a write to a
   209  	// localhost TCP connection, the peer TCP connection can
   210  	// immediately read it. Because it's racy, we skip this test
   211  	// in short mode, and then retry it several times with an
   212  	// increasing sleep in between our final write (via srv.Close
   213  	// below) and the following read.
   214  	if testing.Short() {
   215  		t.Skip("skipping in short mode")
   216  	}
   217  	var err error
   218  	for delay := time.Millisecond; delay <= 64*time.Millisecond; delay *= 2 {
   219  		if err = testConnReadNonzeroAndEOF(t, delay); err == nil {
   220  			return
   221  		}
   222  	}
   223  	t.Error(err)
   224  }
   225  
   226  func testConnReadNonzeroAndEOF(t *testing.T, delay time.Duration) error {
   227  	ln := newLocalListener(t)
   228  	defer ln.Close()
   229  
   230  	srvCh := make(chan *Conn, 1)
   231  	var serr error
   232  	go func() {
   233  		sconn, err := ln.Accept()
   234  		if err != nil {
   235  			serr = err
   236  			srvCh <- nil
   237  			return
   238  		}
   239  		serverConfig := *testConfig
   240  		srv := Server(sconn, &serverConfig)
   241  		if err := srv.Handshake(); err != nil {
   242  			serr = fmt.Errorf("handshake: %v", err)
   243  			srvCh <- nil
   244  			return
   245  		}
   246  		srvCh <- srv
   247  	}()
   248  
   249  	clientConfig := *testConfig
   250  	conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
   251  	if err != nil {
   252  		t.Fatal(err)
   253  	}
   254  	defer conn.Close()
   255  
   256  	srv := <-srvCh
   257  	if srv == nil {
   258  		return serr
   259  	}
   260  
   261  	buf := make([]byte, 6)
   262  
   263  	srv.Write([]byte("foobar"))
   264  	n, err := conn.Read(buf)
   265  	if n != 6 || err != nil || string(buf) != "foobar" {
   266  		return fmt.Errorf("Read = %d, %v, data %q; want 6, nil, foobar", n, err, buf)
   267  	}
   268  
   269  	srv.Write([]byte("abcdef"))
   270  	srv.Close()
   271  	time.Sleep(delay)
   272  	n, err = conn.Read(buf)
   273  	if n != 6 || string(buf) != "abcdef" {
   274  		return fmt.Errorf("Read = %d, buf= %q; want 6, abcdef", n, buf)
   275  	}
   276  	if err != io.EOF {
   277  		return fmt.Errorf("Second Read error = %v; want io.EOF", err)
   278  	}
   279  	return nil
   280  }
   281  
   282  func TestTLSUniqueMatches(t *testing.T) {
   283  	ln := newLocalListener(t)
   284  	defer ln.Close()
   285  
   286  	serverTLSUniques := make(chan []byte)
   287  	go func() {
   288  		for i := 0; i < 2; i++ {
   289  			sconn, err := ln.Accept()
   290  			if err != nil {
   291  				t.Fatal(err)
   292  			}
   293  			serverConfig := *testConfig
   294  			srv := Server(sconn, &serverConfig)
   295  			if err := srv.Handshake(); err != nil {
   296  				t.Fatal(err)
   297  			}
   298  			serverTLSUniques <- srv.ConnectionState().TLSUnique
   299  		}
   300  	}()
   301  
   302  	clientConfig := *testConfig
   303  	clientConfig.ClientSessionCache = NewLRUClientSessionCache(1)
   304  	conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
   305  	if err != nil {
   306  		t.Fatal(err)
   307  	}
   308  	if !bytes.Equal(conn.ConnectionState().TLSUnique, <-serverTLSUniques) {
   309  		t.Error("client and server channel bindings differ")
   310  	}
   311  	conn.Close()
   312  
   313  	conn, err = Dial("tcp", ln.Addr().String(), &clientConfig)
   314  	if err != nil {
   315  		t.Fatal(err)
   316  	}
   317  	defer conn.Close()
   318  	if !conn.ConnectionState().DidResume {
   319  		t.Error("second session did not use resumption")
   320  	}
   321  	if !bytes.Equal(conn.ConnectionState().TLSUnique, <-serverTLSUniques) {
   322  		t.Error("client and server channel bindings differ when session resumption is used")
   323  	}
   324  }
   325  
   326  func TestVerifyHostname(t *testing.T) {
   327  	testenv.MustHaveExternalNetwork(t)
   328  
   329  	c, err := Dial("tcp", "www.google.com:https", nil)
   330  	if err != nil {
   331  		t.Fatal(err)
   332  	}
   333  	if err := c.VerifyHostname("www.google.com"); err != nil {
   334  		t.Fatalf("verify www.google.com: %v", err)
   335  	}
   336  	if err := c.VerifyHostname("www.yahoo.com"); err == nil {
   337  		t.Fatalf("verify www.yahoo.com succeeded")
   338  	}
   339  
   340  	c, err = Dial("tcp", "www.google.com:https", &Config{InsecureSkipVerify: true})
   341  	if err != nil {
   342  		t.Fatal(err)
   343  	}
   344  	if err := c.VerifyHostname("www.google.com"); err == nil {
   345  		t.Fatalf("verify www.google.com succeeded with InsecureSkipVerify=true")
   346  	}
   347  	if err := c.VerifyHostname("www.yahoo.com"); err == nil {
   348  		t.Fatalf("verify www.google.com succeeded with InsecureSkipVerify=true")
   349  	}
   350  }
   351  
   352  func TestVerifyHostnameResumed(t *testing.T) {
   353  	testenv.MustHaveExternalNetwork(t)
   354  
   355  	config := &Config{
   356  		ClientSessionCache: NewLRUClientSessionCache(32),
   357  	}
   358  	for i := 0; i < 2; i++ {
   359  		c, err := Dial("tcp", "www.google.com:https", config)
   360  		if err != nil {
   361  			t.Fatalf("Dial #%d: %v", i, err)
   362  		}
   363  		cs := c.ConnectionState()
   364  		if i > 0 && !cs.DidResume {
   365  			t.Fatalf("Subsequent connection unexpectedly didn't resume")
   366  		}
   367  		if cs.VerifiedChains == nil {
   368  			t.Fatalf("Dial #%d: cs.VerifiedChains == nil", i)
   369  		}
   370  		if err := c.VerifyHostname("www.google.com"); err != nil {
   371  			t.Fatalf("verify www.google.com #%d: %v", i, err)
   372  		}
   373  		c.Close()
   374  	}
   375  }
   376  
   377  func TestConnCloseBreakingWrite(t *testing.T) {
   378  	ln := newLocalListener(t)
   379  	defer ln.Close()
   380  
   381  	srvCh := make(chan *Conn, 1)
   382  	var serr error
   383  	var sconn net.Conn
   384  	go func() {
   385  		var err error
   386  		sconn, err = ln.Accept()
   387  		if err != nil {
   388  			serr = err
   389  			srvCh <- nil
   390  			return
   391  		}
   392  		serverConfig := *testConfig
   393  		srv := Server(sconn, &serverConfig)
   394  		if err := srv.Handshake(); err != nil {
   395  			serr = fmt.Errorf("handshake: %v", err)
   396  			srvCh <- nil
   397  			return
   398  		}
   399  		srvCh <- srv
   400  	}()
   401  
   402  	cconn, err := net.Dial("tcp", ln.Addr().String())
   403  	if err != nil {
   404  		t.Fatal(err)
   405  	}
   406  	defer cconn.Close()
   407  
   408  	conn := &changeImplConn{
   409  		Conn: cconn,
   410  	}
   411  
   412  	clientConfig := *testConfig
   413  	tconn := Client(conn, &clientConfig)
   414  	if err := tconn.Handshake(); err != nil {
   415  		t.Fatal(err)
   416  	}
   417  
   418  	srv := <-srvCh
   419  	if srv == nil {
   420  		t.Fatal(serr)
   421  	}
   422  	defer sconn.Close()
   423  
   424  	connClosed := make(chan struct{})
   425  	conn.closeFunc = func() error {
   426  		close(connClosed)
   427  		return nil
   428  	}
   429  
   430  	inWrite := make(chan bool, 1)
   431  	var errConnClosed = errors.New("conn closed for test")
   432  	conn.writeFunc = func(p []byte) (n int, err error) {
   433  		inWrite <- true
   434  		<-connClosed
   435  		return 0, errConnClosed
   436  	}
   437  
   438  	closeReturned := make(chan bool, 1)
   439  	go func() {
   440  		<-inWrite
   441  		tconn.Close() // test that this doesn't block forever.
   442  		closeReturned <- true
   443  	}()
   444  
   445  	_, err = tconn.Write([]byte("foo"))
   446  	if err != errConnClosed {
   447  		t.Errorf("Write error = %v; want errConnClosed", err)
   448  	}
   449  
   450  	<-closeReturned
   451  	if err := tconn.Close(); err != errClosed {
   452  		t.Errorf("Close error = %v; want errClosed", err)
   453  	}
   454  }
   455  
   456  // changeImplConn is a net.Conn which can change its Write and Close
   457  // methods.
   458  type changeImplConn struct {
   459  	net.Conn
   460  	writeFunc func([]byte) (int, error)
   461  	closeFunc func() error
   462  }
   463  
   464  func (w *changeImplConn) Write(p []byte) (n int, err error) {
   465  	if w.writeFunc != nil {
   466  		return w.writeFunc(p)
   467  	}
   468  	return w.Conn.Write(p)
   469  }
   470  
   471  func (w *changeImplConn) Close() error {
   472  	if w.closeFunc != nil {
   473  		return w.closeFunc()
   474  	}
   475  	return w.Conn.Close()
   476  }
   477  
   478  func throughput(b *testing.B, totalBytes int64, dynamicRecordSizingDisabled bool) {
   479  	ln := newLocalListener(b)
   480  	defer ln.Close()
   481  
   482  	N := b.N
   483  
   484  	go func() {
   485  		for i := 0; i < N; i++ {
   486  			sconn, err := ln.Accept()
   487  			if err != nil {
   488  				// panic rather than synchronize to avoid benchmark overhead
   489  				// (cannot call b.Fatal in goroutine)
   490  				panic(fmt.Errorf("accept: %v", err))
   491  			}
   492  			serverConfig := *testConfig
   493  			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
   494  			srv := Server(sconn, &serverConfig)
   495  			if err := srv.Handshake(); err != nil {
   496  				panic(fmt.Errorf("handshake: %v", err))
   497  			}
   498  			io.Copy(srv, srv)
   499  		}
   500  	}()
   501  
   502  	b.SetBytes(totalBytes)
   503  	clientConfig := *testConfig
   504  	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
   505  
   506  	buf := make([]byte, 1<<14)
   507  	chunks := int(math.Ceil(float64(totalBytes) / float64(len(buf))))
   508  	for i := 0; i < N; i++ {
   509  		conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
   510  		if err != nil {
   511  			b.Fatal(err)
   512  		}
   513  		for j := 0; j < chunks; j++ {
   514  			_, err := conn.Write(buf)
   515  			if err != nil {
   516  				b.Fatal(err)
   517  			}
   518  			_, err = io.ReadFull(conn, buf)
   519  			if err != nil {
   520  				b.Fatal(err)
   521  			}
   522  		}
   523  		conn.Close()
   524  	}
   525  }
   526  
   527  func BenchmarkThroughput(b *testing.B) {
   528  	for _, mode := range []string{"Max", "Dynamic"} {
   529  		for size := 1; size <= 64; size <<= 1 {
   530  			name := fmt.Sprintf("%sPacket/%dMB", mode, size)
   531  			b.Run(name, func(b *testing.B) {
   532  				throughput(b, int64(size<<20), mode == "Max")
   533  			})
   534  		}
   535  	}
   536  }
   537  
   538  type slowConn struct {
   539  	net.Conn
   540  	bps int
   541  }
   542  
   543  func (c *slowConn) Write(p []byte) (int, error) {
   544  	if c.bps == 0 {
   545  		panic("too slow")
   546  	}
   547  	t0 := time.Now()
   548  	wrote := 0
   549  	for wrote < len(p) {
   550  		time.Sleep(100 * time.Microsecond)
   551  		allowed := int(time.Since(t0).Seconds()*float64(c.bps)) / 8
   552  		if allowed > len(p) {
   553  			allowed = len(p)
   554  		}
   555  		if wrote < allowed {
   556  			n, err := c.Conn.Write(p[wrote:allowed])
   557  			wrote += n
   558  			if err != nil {
   559  				return wrote, err
   560  			}
   561  		}
   562  	}
   563  	return len(p), nil
   564  }
   565  
   566  func latency(b *testing.B, bps int, dynamicRecordSizingDisabled bool) {
   567  	ln := newLocalListener(b)
   568  	defer ln.Close()
   569  
   570  	N := b.N
   571  
   572  	go func() {
   573  		for i := 0; i < N; i++ {
   574  			sconn, err := ln.Accept()
   575  			if err != nil {
   576  				// panic rather than synchronize to avoid benchmark overhead
   577  				// (cannot call b.Fatal in goroutine)
   578  				panic(fmt.Errorf("accept: %v", err))
   579  			}
   580  			serverConfig := *testConfig
   581  			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
   582  			srv := Server(&slowConn{sconn, bps}, &serverConfig)
   583  			if err := srv.Handshake(); err != nil {
   584  				panic(fmt.Errorf("handshake: %v", err))
   585  			}
   586  			io.Copy(srv, srv)
   587  		}
   588  	}()
   589  
   590  	clientConfig := *testConfig
   591  	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
   592  
   593  	buf := make([]byte, 16384)
   594  	peek := make([]byte, 1)
   595  
   596  	for i := 0; i < N; i++ {
   597  		conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
   598  		if err != nil {
   599  			b.Fatal(err)
   600  		}
   601  		// make sure we're connected and previous connection has stopped
   602  		if _, err := conn.Write(buf[:1]); err != nil {
   603  			b.Fatal(err)
   604  		}
   605  		if _, err := io.ReadFull(conn, peek); err != nil {
   606  			b.Fatal(err)
   607  		}
   608  		if _, err := conn.Write(buf); err != nil {
   609  			b.Fatal(err)
   610  		}
   611  		if _, err = io.ReadFull(conn, peek); err != nil {
   612  			b.Fatal(err)
   613  		}
   614  		conn.Close()
   615  	}
   616  }
   617  
   618  func BenchmarkLatency(b *testing.B) {
   619  	for _, mode := range []string{"Max", "Dynamic"} {
   620  		for _, kbps := range []int{200, 500, 1000, 2000, 5000} {
   621  			name := fmt.Sprintf("%sPacket/%dkbps", mode, kbps)
   622  			b.Run(name, func(b *testing.B) {
   623  				latency(b, kbps*1000, mode == "Max")
   624  			})
   625  		}
   626  	}
   627  }