Adding upstream version 1.18.10.upstream/1.18.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1611 insertions, 0 deletions

diff --git a/src/crypto/tls/tls_test.go b/src/crypto/tls/tls_test.go
new file mode 100644
index 0000000..d8a43ad
--- /dev/null
+++ b/src/crypto/tls/tls_test.go
@@ -0,0 +1,1611 @@
+// Copyright 2012 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.
+
+package tls
+
+import (
+	"bytes"
+	"context"
+	"crypto"
+	"crypto/x509"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"internal/testenv"
+	"io"
+	"math"
+	"net"
+	"os"
+	"reflect"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+)
+
+var rsaCertPEM = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`
+
+var rsaKeyPEM = testingKey(`-----BEGIN RSA TESTING KEY-----
+MIIBOwIBAAJBANLJhPHhITqQbPklG3ibCVxwGMRfp/v4XqhfdQHdcVfHap6NQ5Wo
+k/4xIA+ui35/MmNartNuC+BdZ1tMuVCPFZcCAwEAAQJAEJ2N+zsR0Xn8/Q6twa4G
+6OB1M1WO+k+ztnX/1SvNeWu8D6GImtupLTYgjZcHufykj09jiHmjHx8u8ZZB/o1N
+MQIhAPW+eyZo7ay3lMz1V01WVjNKK9QSn1MJlb06h/LuYv9FAiEA25WPedKgVyCW
+SmUwbPw8fnTcpqDWE3yTO3vKcebqMSsCIBF3UmVue8YU3jybC3NxuXq3wNm34R8T
+xVLHwDXh/6NJAiEAl2oHGGLz64BuAfjKrqwz7qMYr9HCLIe/YsoWq/olzScCIQDi
+D2lWusoe2/nEqfDVVWGWlyJ7yOmqaVm/iNUN9B2N2g==
+-----END RSA TESTING KEY-----
+`)
+
+// keyPEM is the same as rsaKeyPEM, but declares itself as just
+// "PRIVATE KEY", not "RSA PRIVATE KEY".  https://golang.org/issue/4477
+var keyPEM = testingKey(`-----BEGIN TESTING KEY-----
+MIIBOwIBAAJBANLJhPHhITqQbPklG3ibCVxwGMRfp/v4XqhfdQHdcVfHap6NQ5Wo
+k/4xIA+ui35/MmNartNuC+BdZ1tMuVCPFZcCAwEAAQJAEJ2N+zsR0Xn8/Q6twa4G
+6OB1M1WO+k+ztnX/1SvNeWu8D6GImtupLTYgjZcHufykj09jiHmjHx8u8ZZB/o1N
+MQIhAPW+eyZo7ay3lMz1V01WVjNKK9QSn1MJlb06h/LuYv9FAiEA25WPedKgVyCW
+SmUwbPw8fnTcpqDWE3yTO3vKcebqMSsCIBF3UmVue8YU3jybC3NxuXq3wNm34R8T
+xVLHwDXh/6NJAiEAl2oHGGLz64BuAfjKrqwz7qMYr9HCLIe/YsoWq/olzScCIQDi
+D2lWusoe2/nEqfDVVWGWlyJ7yOmqaVm/iNUN9B2N2g==
+-----END TESTING KEY-----
+`)
+
+var ecdsaCertPEM = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`
+
+var ecdsaKeyPEM = testingKey(`-----BEGIN EC PARAMETERS-----
+BgUrgQQAIw==
+-----END EC PARAMETERS-----
+-----BEGIN EC TESTING KEY-----
+MIHcAgEBBEIBrsoKp0oqcv6/JovJJDoDVSGWdirrkgCWxrprGlzB9o0X8fV675X0
+NwuBenXFfeZvVcwluO7/Q9wkYoPd/t3jGImgBwYFK4EEACOhgYkDgYYABAFj36bL
+06h5JRGUNB1X/Hwuw64uKW2GGJLVPPhoYMcg/ALWaW+d/t+DmV5xikwKssuFq4Bz
+VQldyCXTXGgu7OC0AQCC/Y/+ODK3NFKlRi+AsG3VQDSV4tgHLqZBBus0S6pPcg1q
+kohxS/xfFg/TEwRSSws+roJr4JFKpO2t3/be5OdqmQ==
+-----END EC TESTING KEY-----
+`)
+
+var keyPairTests = []struct {
+	algo string
+	cert string
+	key  string
+}{
+	{"ECDSA", ecdsaCertPEM, ecdsaKeyPEM},
+	{"RSA", rsaCertPEM, rsaKeyPEM},
+	{"RSA-untyped", rsaCertPEM, keyPEM}, // golang.org/issue/4477
+}
+
+func TestX509KeyPair(t *testing.T) {
+	t.Parallel()
+	var pem []byte
+	for _, test := range keyPairTests {
+		pem = []byte(test.cert + test.key)
+		if _, err := X509KeyPair(pem, pem); err != nil {
+			t.Errorf("Failed to load %s cert followed by %s key: %s", test.algo, test.algo, err)
+		}
+		pem = []byte(test.key + test.cert)
+		if _, err := X509KeyPair(pem, pem); err != nil {
+			t.Errorf("Failed to load %s key followed by %s cert: %s", test.algo, test.algo, err)
+		}
+	}
+}
+
+func TestX509KeyPairErrors(t *testing.T) {
+	_, err := X509KeyPair([]byte(rsaKeyPEM), []byte(rsaCertPEM))
+	if err == nil {
+		t.Fatalf("X509KeyPair didn't return an error when arguments were switched")
+	}
+	if subStr := "been switched"; !strings.Contains(err.Error(), subStr) {
+		t.Fatalf("Expected %q in the error when switching arguments to X509KeyPair, but the error was %q", subStr, err)
+	}
+
+	_, err = X509KeyPair([]byte(rsaCertPEM), []byte(rsaCertPEM))
+	if err == nil {
+		t.Fatalf("X509KeyPair didn't return an error when both arguments were certificates")
+	}
+	if subStr := "certificate"; !strings.Contains(err.Error(), subStr) {
+		t.Fatalf("Expected %q in the error when both arguments to X509KeyPair were certificates, but the error was %q", subStr, err)
+	}
+
+	const nonsensePEM = `
+-----BEGIN NONSENSE-----
+Zm9vZm9vZm9v
+-----END NONSENSE-----
+`
+
+	_, err = X509KeyPair([]byte(nonsensePEM), []byte(nonsensePEM))
+	if err == nil {
+		t.Fatalf("X509KeyPair didn't return an error when both arguments were nonsense")
+	}
+	if subStr := "NONSENSE"; !strings.Contains(err.Error(), subStr) {
+		t.Fatalf("Expected %q in the error when both arguments to X509KeyPair were nonsense, but the error was %q", subStr, err)
+	}
+}
+
+func TestX509MixedKeyPair(t *testing.T) {
+	if _, err := X509KeyPair([]byte(rsaCertPEM), []byte(ecdsaKeyPEM)); err == nil {
+		t.Error("Load of RSA certificate succeeded with ECDSA private key")
+	}
+	if _, err := X509KeyPair([]byte(ecdsaCertPEM), []byte(rsaKeyPEM)); err == nil {
+		t.Error("Load of ECDSA certificate succeeded with RSA private key")
+	}
+}
+
+func newLocalListener(t testing.TB) net.Listener {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		ln, err = net.Listen("tcp6", "[::1]:0")
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return ln
+}
+
+func TestDialTimeout(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	listener := newLocalListener(t)
+
+	addr := listener.Addr().String()
+	defer listener.Close()
+
+	complete := make(chan bool)
+	defer close(complete)
+
+	go func() {
+		conn, err := listener.Accept()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		<-complete
+		conn.Close()
+	}()
+
+	dialer := &net.Dialer{
+		Timeout: 10 * time.Millisecond,
+	}
+
+	var err error
+	if _, err = DialWithDialer(dialer, "tcp", addr, nil); err == nil {
+		t.Fatal("DialWithTimeout completed successfully")
+	}
+
+	if !isTimeoutError(err) {
+		t.Errorf("resulting error not a timeout: %v\nType %T: %#v", err, err, err)
+	}
+}
+
+func TestDeadlineOnWrite(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	srvCh := make(chan *Conn, 1)
+
+	go func() {
+		sconn, err := ln.Accept()
+		if err != nil {
+			srvCh <- nil
+			return
+		}
+		srv := Server(sconn, testConfig.Clone())
+		if err := srv.Handshake(); err != nil {
+			srvCh <- nil
+			return
+		}
+		srvCh <- srv
+	}()
+
+	clientConfig := testConfig.Clone()
+	clientConfig.MaxVersion = VersionTLS12
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	srv := <-srvCh
+	if srv == nil {
+		t.Error(err)
+	}
+
+	// Make sure the client/server is setup correctly and is able to do a typical Write/Read
+	buf := make([]byte, 6)
+	if _, err := srv.Write([]byte("foobar")); err != nil {
+		t.Errorf("Write err: %v", err)
+	}
+	if n, err := conn.Read(buf); n != 6 || err != nil || string(buf) != "foobar" {
+		t.Errorf("Read = %d, %v, data %q; want 6, nil, foobar", n, err, buf)
+	}
+
+	// Set a deadline which should cause Write to timeout
+	if err = srv.SetDeadline(time.Now()); err != nil {
+		t.Fatalf("SetDeadline(time.Now()) err: %v", err)
+	}
+	if _, err = srv.Write([]byte("should fail")); err == nil {
+		t.Fatal("Write should have timed out")
+	}
+
+	// Clear deadline and make sure it still times out
+	if err = srv.SetDeadline(time.Time{}); err != nil {
+		t.Fatalf("SetDeadline(time.Time{}) err: %v", err)
+	}
+	if _, err = srv.Write([]byte("This connection is permanently broken")); err == nil {
+		t.Fatal("Write which previously failed should still time out")
+	}
+
+	// Verify the error
+	if ne := err.(net.Error); ne.Temporary() != false {
+		t.Error("Write timed out but incorrectly classified the error as Temporary")
+	}
+	if !isTimeoutError(err) {
+		t.Error("Write timed out but did not classify the error as a Timeout")
+	}
+}
+
+type readerFunc func([]byte) (int, error)
+
+func (f readerFunc) Read(b []byte) (int, error) { return f(b) }
+
+// TestDialer tests that tls.Dialer.DialContext can abort in the middle of a handshake.
+// (The other cases are all handled by the existing dial tests in this package, which
+// all also flow through the same code shared code paths)
+func TestDialer(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	unblockServer := make(chan struct{}) // close-only
+	defer close(unblockServer)
+	go func() {
+		conn, err := ln.Accept()
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		<-unblockServer
+	}()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	d := Dialer{Config: &Config{
+		Rand: readerFunc(func(b []byte) (n int, err error) {
+			// By the time crypto/tls wants randomness, that means it has a TCP
+			// connection, so we're past the Dialer's dial and now blocked
+			// in a handshake. Cancel our context and see if we get unstuck.
+			// (Our TCP listener above never reads or writes, so the Handshake
+			// would otherwise be stuck forever)
+			cancel()
+			return len(b), nil
+		}),
+		ServerName: "foo",
+	}}
+	_, err := d.DialContext(ctx, "tcp", ln.Addr().String())
+	if err != context.Canceled {
+		t.Errorf("err = %v; want context.Canceled", err)
+	}
+}
+
+func isTimeoutError(err error) bool {
+	if ne, ok := err.(net.Error); ok {
+		return ne.Timeout()
+	}
+	return false
+}
+
+// tests that Conn.Read returns (non-zero, io.EOF) instead of
+// (non-zero, nil) when a Close (alertCloseNotify) is sitting right
+// behind the application data in the buffer.
+func TestConnReadNonzeroAndEOF(t *testing.T) {
+	// This test is racy: it assumes that after a write to a
+	// localhost TCP connection, the peer TCP connection can
+	// immediately read it. Because it's racy, we skip this test
+	// in short mode, and then retry it several times with an
+	// increasing sleep in between our final write (via srv.Close
+	// below) and the following read.
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	var err error
+	for delay := time.Millisecond; delay <= 64*time.Millisecond; delay *= 2 {
+		if err = testConnReadNonzeroAndEOF(t, delay); err == nil {
+			return
+		}
+	}
+	t.Error(err)
+}
+
+func testConnReadNonzeroAndEOF(t *testing.T, delay time.Duration) error {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	srvCh := make(chan *Conn, 1)
+	var serr error
+	go func() {
+		sconn, err := ln.Accept()
+		if err != nil {
+			serr = err
+			srvCh <- nil
+			return
+		}
+		serverConfig := testConfig.Clone()
+		srv := Server(sconn, serverConfig)
+		if err := srv.Handshake(); err != nil {
+			serr = fmt.Errorf("handshake: %v", err)
+			srvCh <- nil
+			return
+		}
+		srvCh <- srv
+	}()
+
+	clientConfig := testConfig.Clone()
+	// In TLS 1.3, alerts are encrypted and disguised as application data, so
+	// the opportunistic peek won't work.
+	clientConfig.MaxVersion = VersionTLS12
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	srv := <-srvCh
+	if srv == nil {
+		return serr
+	}
+
+	buf := make([]byte, 6)
+
+	srv.Write([]byte("foobar"))
+	n, err := conn.Read(buf)
+	if n != 6 || err != nil || string(buf) != "foobar" {
+		return fmt.Errorf("Read = %d, %v, data %q; want 6, nil, foobar", n, err, buf)
+	}
+
+	srv.Write([]byte("abcdef"))
+	srv.Close()
+	time.Sleep(delay)
+	n, err = conn.Read(buf)
+	if n != 6 || string(buf) != "abcdef" {
+		return fmt.Errorf("Read = %d, buf= %q; want 6, abcdef", n, buf)
+	}
+	if err != io.EOF {
+		return fmt.Errorf("Second Read error = %v; want io.EOF", err)
+	}
+	return nil
+}
+
+func TestTLSUniqueMatches(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	serverTLSUniques := make(chan []byte)
+	parentDone := make(chan struct{})
+	childDone := make(chan struct{})
+	defer close(parentDone)
+	go func() {
+		defer close(childDone)
+		for i := 0; i < 2; i++ {
+			sconn, err := ln.Accept()
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			serverConfig := testConfig.Clone()
+			serverConfig.MaxVersion = VersionTLS12 // TLSUnique is not defined in TLS 1.3
+			srv := Server(sconn, serverConfig)
+			if err := srv.Handshake(); err != nil {
+				t.Error(err)
+				return
+			}
+			select {
+			case <-parentDone:
+				return
+			case serverTLSUniques <- srv.ConnectionState().TLSUnique:
+			}
+		}
+	}()
+
+	clientConfig := testConfig.Clone()
+	clientConfig.ClientSessionCache = NewLRUClientSessionCache(1)
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var serverTLSUniquesValue []byte
+	select {
+	case <-childDone:
+		return
+	case serverTLSUniquesValue = <-serverTLSUniques:
+	}
+
+	if !bytes.Equal(conn.ConnectionState().TLSUnique, serverTLSUniquesValue) {
+		t.Error("client and server channel bindings differ")
+	}
+	conn.Close()
+
+	conn, err = Dial("tcp", ln.Addr().String(), clientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+	if !conn.ConnectionState().DidResume {
+		t.Error("second session did not use resumption")
+	}
+
+	select {
+	case <-childDone:
+		return
+	case serverTLSUniquesValue = <-serverTLSUniques:
+	}
+
+	if !bytes.Equal(conn.ConnectionState().TLSUnique, serverTLSUniquesValue) {
+		t.Error("client and server channel bindings differ when session resumption is used")
+	}
+}
+
+func TestVerifyHostname(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
+	c, err := Dial("tcp", "www.google.com:https", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.VerifyHostname("www.google.com"); err != nil {
+		t.Fatalf("verify www.google.com: %v", err)
+	}
+	if err := c.VerifyHostname("www.yahoo.com"); err == nil {
+		t.Fatalf("verify www.yahoo.com succeeded")
+	}
+
+	c, err = Dial("tcp", "www.google.com:https", &Config{InsecureSkipVerify: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.VerifyHostname("www.google.com"); err == nil {
+		t.Fatalf("verify www.google.com succeeded with InsecureSkipVerify=true")
+	}
+}
+
+func TestConnCloseBreakingWrite(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	srvCh := make(chan *Conn, 1)
+	var serr error
+	var sconn net.Conn
+	go func() {
+		var err error
+		sconn, err = ln.Accept()
+		if err != nil {
+			serr = err
+			srvCh <- nil
+			return
+		}
+		serverConfig := testConfig.Clone()
+		srv := Server(sconn, serverConfig)
+		if err := srv.Handshake(); err != nil {
+			serr = fmt.Errorf("handshake: %v", err)
+			srvCh <- nil
+			return
+		}
+		srvCh <- srv
+	}()
+
+	cconn, err := net.Dial("tcp", ln.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cconn.Close()
+
+	conn := &changeImplConn{
+		Conn: cconn,
+	}
+
+	clientConfig := testConfig.Clone()
+	tconn := Client(conn, clientConfig)
+	if err := tconn.Handshake(); err != nil {
+		t.Fatal(err)
+	}
+
+	srv := <-srvCh
+	if srv == nil {
+		t.Fatal(serr)
+	}
+	defer sconn.Close()
+
+	connClosed := make(chan struct{})
+	conn.closeFunc = func() error {
+		close(connClosed)
+		return nil
+	}
+
+	inWrite := make(chan bool, 1)
+	var errConnClosed = errors.New("conn closed for test")
+	conn.writeFunc = func(p []byte) (n int, err error) {
+		inWrite <- true
+		<-connClosed
+		return 0, errConnClosed
+	}
+
+	closeReturned := make(chan bool, 1)
+	go func() {
+		<-inWrite
+		tconn.Close() // test that this doesn't block forever.
+		closeReturned <- true
+	}()
+
+	_, err = tconn.Write([]byte("foo"))
+	if err != errConnClosed {
+		t.Errorf("Write error = %v; want errConnClosed", err)
+	}
+
+	<-closeReturned
+	if err := tconn.Close(); err != net.ErrClosed {
+		t.Errorf("Close error = %v; want net.ErrClosed", err)
+	}
+}
+
+func TestConnCloseWrite(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	clientDoneChan := make(chan struct{})
+
+	serverCloseWrite := func() error {
+		sconn, err := ln.Accept()
+		if err != nil {
+			return fmt.Errorf("accept: %v", err)
+		}
+		defer sconn.Close()
+
+		serverConfig := testConfig.Clone()
+		srv := Server(sconn, serverConfig)
+		if err := srv.Handshake(); err != nil {
+			return fmt.Errorf("handshake: %v", err)
+		}
+		defer srv.Close()
+
+		data, err := io.ReadAll(srv)
+		if err != nil {
+			return err
+		}
+		if len(data) > 0 {
+			return fmt.Errorf("Read data = %q; want nothing", data)
+		}
+
+		if err := srv.CloseWrite(); err != nil {
+			return fmt.Errorf("server CloseWrite: %v", err)
+		}
+
+		// Wait for clientCloseWrite to finish, so we know we
+		// tested the CloseWrite before we defer the
+		// sconn.Close above, which would also cause the
+		// client to unblock like CloseWrite.
+		<-clientDoneChan
+		return nil
+	}
+
+	clientCloseWrite := func() error {
+		defer close(clientDoneChan)
+
+		clientConfig := testConfig.Clone()
+		conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+		if err != nil {
+			return err
+		}
+		if err := conn.Handshake(); err != nil {
+			return err
+		}
+		defer conn.Close()
+
+		if err := conn.CloseWrite(); err != nil {
+			return fmt.Errorf("client CloseWrite: %v", err)
+		}
+
+		if _, err := conn.Write([]byte{0}); err != errShutdown {
+			return fmt.Errorf("CloseWrite error = %v; want errShutdown", err)
+		}
+
+		data, err := io.ReadAll(conn)
+		if err != nil {
+			return err
+		}
+		if len(data) > 0 {
+			return fmt.Errorf("Read data = %q; want nothing", data)
+		}
+		return nil
+	}
+
+	errChan := make(chan error, 2)
+
+	go func() { errChan <- serverCloseWrite() }()
+	go func() { errChan <- clientCloseWrite() }()
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-errChan:
+			if err != nil {
+				t.Fatal(err)
+			}
+		case <-time.After(10 * time.Second):
+			t.Fatal("deadlock")
+		}
+	}
+
+	// Also test CloseWrite being called before the handshake is
+	// finished:
+	{
+		ln2 := newLocalListener(t)
+		defer ln2.Close()
+
+		netConn, err := net.Dial("tcp", ln2.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer netConn.Close()
+		conn := Client(netConn, testConfig.Clone())
+
+		if err := conn.CloseWrite(); err != errEarlyCloseWrite {
+			t.Errorf("CloseWrite error = %v; want errEarlyCloseWrite", err)
+		}
+	}
+}
+
+func TestWarningAlertFlood(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	server := func() error {
+		sconn, err := ln.Accept()
+		if err != nil {
+			return fmt.Errorf("accept: %v", err)
+		}
+		defer sconn.Close()
+
+		serverConfig := testConfig.Clone()
+		srv := Server(sconn, serverConfig)
+		if err := srv.Handshake(); err != nil {
+			return fmt.Errorf("handshake: %v", err)
+		}
+		defer srv.Close()
+
+		_, err = io.ReadAll(srv)
+		if err == nil {
+			return errors.New("unexpected lack of error from server")
+		}
+		const expected = "too many ignored"
+		if str := err.Error(); !strings.Contains(str, expected) {
+			return fmt.Errorf("expected error containing %q, but saw: %s", expected, str)
+		}
+
+		return nil
+	}
+
+	errChan := make(chan error, 1)
+	go func() { errChan <- server() }()
+
+	clientConfig := testConfig.Clone()
+	clientConfig.MaxVersion = VersionTLS12 // there are no warning alerts in TLS 1.3
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+	if err := conn.Handshake(); err != nil {
+		t.Fatal(err)
+	}
+
+	for i := 0; i < maxUselessRecords+1; i++ {
+		conn.sendAlert(alertNoRenegotiation)
+	}
+
+	if err := <-errChan; err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCloneFuncFields(t *testing.T) {
+	const expectedCount = 6
+	called := 0
+
+	c1 := Config{
+		Time: func() time.Time {
+			called |= 1 << 0
+			return time.Time{}
+		},
+		GetCertificate: func(*ClientHelloInfo) (*Certificate, error) {
+			called |= 1 << 1
+			return nil, nil
+		},
+		GetClientCertificate: func(*CertificateRequestInfo) (*Certificate, error) {
+			called |= 1 << 2
+			return nil, nil
+		},
+		GetConfigForClient: func(*ClientHelloInfo) (*Config, error) {
+			called |= 1 << 3
+			return nil, nil
+		},
+		VerifyPeerCertificate: func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error {
+			called |= 1 << 4
+			return nil
+		},
+		VerifyConnection: func(ConnectionState) error {
+			called |= 1 << 5
+			return nil
+		},
+	}
+
+	c2 := c1.Clone()
+
+	c2.Time()
+	c2.GetCertificate(nil)
+	c2.GetClientCertificate(nil)
+	c2.GetConfigForClient(nil)
+	c2.VerifyPeerCertificate(nil, nil)
+	c2.VerifyConnection(ConnectionState{})
+
+	if called != (1<<expectedCount)-1 {
+		t.Fatalf("expected %d calls but saw calls %b", expectedCount, called)
+	}
+}
+
+func TestCloneNonFuncFields(t *testing.T) {
+	var c1 Config
+	v := reflect.ValueOf(&c1).Elem()
+
+	typ := v.Type()
+	for i := 0; i < typ.NumField(); i++ {
+		f := v.Field(i)
+		// testing/quick can't handle functions or interfaces and so
+		// isn't used here.
+		switch fn := typ.Field(i).Name; fn {
+		case "Rand":
+			f.Set(reflect.ValueOf(io.Reader(os.Stdin)))
+		case "Time", "GetCertificate", "GetConfigForClient", "VerifyPeerCertificate", "VerifyConnection", "GetClientCertificate":
+			// DeepEqual can't compare functions. If you add a
+			// function field to this list, you must also change
+			// TestCloneFuncFields to ensure that the func field is
+			// cloned.
+		case "Certificates":
+			f.Set(reflect.ValueOf([]Certificate{
+				{Certificate: [][]byte{{'b'}}},
+			}))
+		case "NameToCertificate":
+			f.Set(reflect.ValueOf(map[string]*Certificate{"a": nil}))
+		case "RootCAs", "ClientCAs":
+			f.Set(reflect.ValueOf(x509.NewCertPool()))
+		case "ClientSessionCache":
+			f.Set(reflect.ValueOf(NewLRUClientSessionCache(10)))
+		case "KeyLogWriter":
+			f.Set(reflect.ValueOf(io.Writer(os.Stdout)))
+		case "NextProtos":
+			f.Set(reflect.ValueOf([]string{"a", "b"}))
+		case "ServerName":
+			f.Set(reflect.ValueOf("b"))
+		case "ClientAuth":
+			f.Set(reflect.ValueOf(VerifyClientCertIfGiven))
+		case "InsecureSkipVerify", "SessionTicketsDisabled", "DynamicRecordSizingDisabled", "PreferServerCipherSuites":
+			f.Set(reflect.ValueOf(true))
+		case "MinVersion", "MaxVersion":
+			f.Set(reflect.ValueOf(uint16(VersionTLS12)))
+		case "SessionTicketKey":
+			f.Set(reflect.ValueOf([32]byte{}))
+		case "CipherSuites":
+			f.Set(reflect.ValueOf([]uint16{1, 2}))
+		case "CurvePreferences":
+			f.Set(reflect.ValueOf([]CurveID{CurveP256}))
+		case "Renegotiation":
+			f.Set(reflect.ValueOf(RenegotiateOnceAsClient))
+		case "mutex", "autoSessionTicketKeys", "sessionTicketKeys":
+			continue // these are unexported fields that are handled separately
+		default:
+			t.Errorf("all fields must be accounted for, but saw unknown field %q", fn)
+		}
+	}
+	// Set the unexported fields related to session ticket keys, which are copied with Clone().
+	c1.autoSessionTicketKeys = []ticketKey{c1.ticketKeyFromBytes(c1.SessionTicketKey)}
+	c1.sessionTicketKeys = []ticketKey{c1.ticketKeyFromBytes(c1.SessionTicketKey)}
+
+	c2 := c1.Clone()
+	if !reflect.DeepEqual(&c1, c2) {
+		t.Errorf("clone failed to copy a field")
+	}
+}
+
+func TestCloneNilConfig(t *testing.T) {
+	var config *Config
+	if cc := config.Clone(); cc != nil {
+		t.Fatalf("Clone with nil should return nil, got: %+v", cc)
+	}
+}
+
+// changeImplConn is a net.Conn which can change its Write and Close
+// methods.
+type changeImplConn struct {
+	net.Conn
+	writeFunc func([]byte) (int, error)
+	closeFunc func() error
+}
+
+func (w *changeImplConn) Write(p []byte) (n int, err error) {
+	if w.writeFunc != nil {
+		return w.writeFunc(p)
+	}
+	return w.Conn.Write(p)
+}
+
+func (w *changeImplConn) Close() error {
+	if w.closeFunc != nil {
+		return w.closeFunc()
+	}
+	return w.Conn.Close()
+}
+
+func throughput(b *testing.B, version uint16, totalBytes int64, dynamicRecordSizingDisabled bool) {
+	ln := newLocalListener(b)
+	defer ln.Close()
+
+	N := b.N
+
+	// Less than 64KB because Windows appears to use a TCP rwin < 64KB.
+	// See Issue #15899.
+	const bufsize = 32 << 10
+
+	go func() {
+		buf := make([]byte, bufsize)
+		for i := 0; i < N; i++ {
+			sconn, err := ln.Accept()
+			if err != nil {
+				// panic rather than synchronize to avoid benchmark overhead
+				// (cannot call b.Fatal in goroutine)
+				panic(fmt.Errorf("accept: %v", err))
+			}
+			serverConfig := testConfig.Clone()
+			serverConfig.CipherSuites = nil // the defaults may prefer faster ciphers
+			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+			srv := Server(sconn, serverConfig)
+			if err := srv.Handshake(); err != nil {
+				panic(fmt.Errorf("handshake: %v", err))
+			}
+			if _, err := io.CopyBuffer(srv, srv, buf); err != nil {
+				panic(fmt.Errorf("copy buffer: %v", err))
+			}
+		}
+	}()
+
+	b.SetBytes(totalBytes)
+	clientConfig := testConfig.Clone()
+	clientConfig.CipherSuites = nil // the defaults may prefer faster ciphers
+	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+	clientConfig.MaxVersion = version
+
+	buf := make([]byte, bufsize)
+	chunks := int(math.Ceil(float64(totalBytes) / float64(len(buf))))
+	for i := 0; i < N; i++ {
+		conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+		if err != nil {
+			b.Fatal(err)
+		}
+		for j := 0; j < chunks; j++ {
+			_, err := conn.Write(buf)
+			if err != nil {
+				b.Fatal(err)
+			}
+			_, err = io.ReadFull(conn, buf)
+			if err != nil {
+				b.Fatal(err)
+			}
+		}
+		conn.Close()
+	}
+}
+
+func BenchmarkThroughput(b *testing.B) {
+	for _, mode := range []string{"Max", "Dynamic"} {
+		for size := 1; size <= 64; size <<= 1 {
+			name := fmt.Sprintf("%sPacket/%dMB", mode, size)
+			b.Run(name, func(b *testing.B) {
+				b.Run("TLSv12", func(b *testing.B) {
+					throughput(b, VersionTLS12, int64(size<<20), mode == "Max")
+				})
+				b.Run("TLSv13", func(b *testing.B) {
+					throughput(b, VersionTLS13, int64(size<<20), mode == "Max")
+				})
+			})
+		}
+	}
+}
+
+type slowConn struct {
+	net.Conn
+	bps int
+}
+
+func (c *slowConn) Write(p []byte) (int, error) {
+	if c.bps == 0 {
+		panic("too slow")
+	}
+	t0 := time.Now()
+	wrote := 0
+	for wrote < len(p) {
+		time.Sleep(100 * time.Microsecond)
+		allowed := int(time.Since(t0).Seconds()*float64(c.bps)) / 8
+		if allowed > len(p) {
+			allowed = len(p)
+		}
+		if wrote < allowed {
+			n, err := c.Conn.Write(p[wrote:allowed])
+			wrote += n
+			if err != nil {
+				return wrote, err
+			}
+		}
+	}
+	return len(p), nil
+}
+
+func latency(b *testing.B, version uint16, bps int, dynamicRecordSizingDisabled bool) {
+	ln := newLocalListener(b)
+	defer ln.Close()
+
+	N := b.N
+
+	go func() {
+		for i := 0; i < N; i++ {
+			sconn, err := ln.Accept()
+			if err != nil {
+				// panic rather than synchronize to avoid benchmark overhead
+				// (cannot call b.Fatal in goroutine)
+				panic(fmt.Errorf("accept: %v", err))
+			}
+			serverConfig := testConfig.Clone()
+			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+			srv := Server(&slowConn{sconn, bps}, serverConfig)
+			if err := srv.Handshake(); err != nil {
+				panic(fmt.Errorf("handshake: %v", err))
+			}
+			io.Copy(srv, srv)
+		}
+	}()
+
+	clientConfig := testConfig.Clone()
+	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+	clientConfig.MaxVersion = version
+
+	buf := make([]byte, 16384)
+	peek := make([]byte, 1)
+
+	for i := 0; i < N; i++ {
+		conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+		if err != nil {
+			b.Fatal(err)
+		}
+		// make sure we're connected and previous connection has stopped
+		if _, err := conn.Write(buf[:1]); err != nil {
+			b.Fatal(err)
+		}
+		if _, err := io.ReadFull(conn, peek); err != nil {
+			b.Fatal(err)
+		}
+		if _, err := conn.Write(buf); err != nil {
+			b.Fatal(err)
+		}
+		if _, err = io.ReadFull(conn, peek); err != nil {
+			b.Fatal(err)
+		}
+		conn.Close()
+	}
+}
+
+func BenchmarkLatency(b *testing.B) {
+	for _, mode := range []string{"Max", "Dynamic"} {
+		for _, kbps := range []int{200, 500, 1000, 2000, 5000} {
+			name := fmt.Sprintf("%sPacket/%dkbps", mode, kbps)
+			b.Run(name, func(b *testing.B) {
+				b.Run("TLSv12", func(b *testing.B) {
+					latency(b, VersionTLS12, kbps*1000, mode == "Max")
+				})
+				b.Run("TLSv13", func(b *testing.B) {
+					latency(b, VersionTLS13, kbps*1000, mode == "Max")
+				})
+			})
+		}
+	}
+}
+
+func TestConnectionStateMarshal(t *testing.T) {
+	cs := &ConnectionState{}
+	_, err := json.Marshal(cs)
+	if err != nil {
+		t.Errorf("json.Marshal failed on ConnectionState: %v", err)
+	}
+}
+
+func TestConnectionState(t *testing.T) {
+	issuer, err := x509.ParseCertificate(testRSACertificateIssuer)
+	if err != nil {
+		panic(err)
+	}
+	rootCAs := x509.NewCertPool()
+	rootCAs.AddCert(issuer)
+
+	now := func() time.Time { return time.Unix(1476984729, 0) }
+
+	const alpnProtocol = "golang"
+	const serverName = "example.golang"
+	var scts = [][]byte{[]byte("dummy sct 1"), []byte("dummy sct 2")}
+	var ocsp = []byte("dummy ocsp")
+
+	for _, v := range []uint16{VersionTLS12, VersionTLS13} {
+		var name string
+		switch v {
+		case VersionTLS12:
+			name = "TLSv12"
+		case VersionTLS13:
+			name = "TLSv13"
+		}
+		t.Run(name, func(t *testing.T) {
+			config := &Config{
+				Time:         now,
+				Rand:         zeroSource{},
+				Certificates: make([]Certificate, 1),
+				MaxVersion:   v,
+				RootCAs:      rootCAs,
+				ClientCAs:    rootCAs,
+				ClientAuth:   RequireAndVerifyClientCert,
+				NextProtos:   []string{alpnProtocol},
+				ServerName:   serverName,
+			}
+			config.Certificates[0].Certificate = [][]byte{testRSACertificate}
+			config.Certificates[0].PrivateKey = testRSAPrivateKey
+			config.Certificates[0].SignedCertificateTimestamps = scts
+			config.Certificates[0].OCSPStaple = ocsp
+
+			ss, cs, err := testHandshake(t, config, config)
+			if err != nil {
+				t.Fatalf("Handshake failed: %v", err)
+			}
+
+			if ss.Version != v || cs.Version != v {
+				t.Errorf("Got versions %x (server) and %x (client), expected %x", ss.Version, cs.Version, v)
+			}
+
+			if !ss.HandshakeComplete || !cs.HandshakeComplete {
+				t.Errorf("Got HandshakeComplete %v (server) and %v (client), expected true", ss.HandshakeComplete, cs.HandshakeComplete)
+			}
+
+			if ss.DidResume || cs.DidResume {
+				t.Errorf("Got DidResume %v (server) and %v (client), expected false", ss.DidResume, cs.DidResume)
+			}
+
+			if ss.CipherSuite == 0 || cs.CipherSuite == 0 {
+				t.Errorf("Got invalid cipher suite: %v (server) and %v (client)", ss.CipherSuite, cs.CipherSuite)
+			}
+
+			if ss.NegotiatedProtocol != alpnProtocol || cs.NegotiatedProtocol != alpnProtocol {
+				t.Errorf("Got negotiated protocol %q (server) and %q (client), expected %q", ss.NegotiatedProtocol, cs.NegotiatedProtocol, alpnProtocol)
+			}
+
+			if !cs.NegotiatedProtocolIsMutual {
+				t.Errorf("Got false NegotiatedProtocolIsMutual on the client side")
+			}
+			// NegotiatedProtocolIsMutual on the server side is unspecified.
+
+			if ss.ServerName != serverName {
+				t.Errorf("Got server name %q, expected %q", ss.ServerName, serverName)
+			}
+			if cs.ServerName != serverName {
+				t.Errorf("Got server name on client connection %q, expected %q", cs.ServerName, serverName)
+			}
+
+			if len(ss.PeerCertificates) != 1 || len(cs.PeerCertificates) != 1 {
+				t.Errorf("Got %d (server) and %d (client) peer certificates, expected %d", len(ss.PeerCertificates), len(cs.PeerCertificates), 1)
+			}
+
+			if len(ss.VerifiedChains) != 1 || len(cs.VerifiedChains) != 1 {
+				t.Errorf("Got %d (server) and %d (client) verified chains, expected %d", len(ss.VerifiedChains), len(cs.VerifiedChains), 1)
+			} else if len(ss.VerifiedChains[0]) != 2 || len(cs.VerifiedChains[0]) != 2 {
+				t.Errorf("Got %d (server) and %d (client) long verified chain, expected %d", len(ss.VerifiedChains[0]), len(cs.VerifiedChains[0]), 2)
+			}
+
+			if len(cs.SignedCertificateTimestamps) != 2 {
+				t.Errorf("Got %d SCTs, expected %d", len(cs.SignedCertificateTimestamps), 2)
+			}
+			if !bytes.Equal(cs.OCSPResponse, ocsp) {
+				t.Errorf("Got OCSPs %x, expected %x", cs.OCSPResponse, ocsp)
+			}
+			// Only TLS 1.3 supports OCSP and SCTs on client certs.
+			if v == VersionTLS13 {
+				if len(ss.SignedCertificateTimestamps) != 2 {
+					t.Errorf("Got %d client SCTs, expected %d", len(ss.SignedCertificateTimestamps), 2)
+				}
+				if !bytes.Equal(ss.OCSPResponse, ocsp) {
+					t.Errorf("Got client OCSPs %x, expected %x", ss.OCSPResponse, ocsp)
+				}
+			}
+
+			if v == VersionTLS13 {
+				if ss.TLSUnique != nil || cs.TLSUnique != nil {
+					t.Errorf("Got TLSUnique %x (server) and %x (client), expected nil in TLS 1.3", ss.TLSUnique, cs.TLSUnique)
+				}
+			} else {
+				if ss.TLSUnique == nil || cs.TLSUnique == nil {
+					t.Errorf("Got TLSUnique %x (server) and %x (client), expected non-nil", ss.TLSUnique, cs.TLSUnique)
+				}
+			}
+		})
+	}
+}
+
+// Issue 28744: Ensure that we don't modify memory
+// that Config doesn't own such as Certificates.
+func TestBuildNameToCertificate_doesntModifyCertificates(t *testing.T) {
+	c0 := Certificate{
+		Certificate: [][]byte{testRSACertificate},
+		PrivateKey:  testRSAPrivateKey,
+	}
+	c1 := Certificate{
+		Certificate: [][]byte{testSNICertificate},
+		PrivateKey:  testRSAPrivateKey,
+	}
+	config := testConfig.Clone()
+	config.Certificates = []Certificate{c0, c1}
+
+	config.BuildNameToCertificate()
+	got := config.Certificates
+	want := []Certificate{c0, c1}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("Certificates were mutated by BuildNameToCertificate\nGot: %#v\nWant: %#v\n", got, want)
+	}
+}
+
+func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "PRIVATE KEY") }
+
+func TestClientHelloInfo_SupportsCertificate(t *testing.T) {
+	rsaCert := &Certificate{
+		Certificate: [][]byte{testRSACertificate},
+		PrivateKey:  testRSAPrivateKey,
+	}
+	pkcs1Cert := &Certificate{
+		Certificate:                  [][]byte{testRSACertificate},
+		PrivateKey:                   testRSAPrivateKey,
+		SupportedSignatureAlgorithms: []SignatureScheme{PKCS1WithSHA1, PKCS1WithSHA256},
+	}
+	ecdsaCert := &Certificate{
+		// ECDSA P-256 certificate
+		Certificate: [][]byte{testP256Certificate},
+		PrivateKey:  testP256PrivateKey,
+	}
+	ed25519Cert := &Certificate{
+		Certificate: [][]byte{testEd25519Certificate},
+		PrivateKey:  testEd25519PrivateKey,
+	}
+
+	tests := []struct {
+		c       *Certificate
+		chi     *ClientHelloInfo
+		wantErr string
+	}{
+		{rsaCert, &ClientHelloInfo{
+			ServerName:        "example.golang",
+			SignatureSchemes:  []SignatureScheme{PSSWithSHA256},
+			SupportedVersions: []uint16{VersionTLS13},
+		}, ""},
+		{ecdsaCert, &ClientHelloInfo{
+			SignatureSchemes:  []SignatureScheme{PSSWithSHA256, ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS13, VersionTLS12},
+		}, ""},
+		{rsaCert, &ClientHelloInfo{
+			ServerName:        "example.com",
+			SignatureSchemes:  []SignatureScheme{PSSWithSHA256},
+			SupportedVersions: []uint16{VersionTLS13},
+		}, "not valid for requested server name"},
+		{ecdsaCert, &ClientHelloInfo{
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP384AndSHA384},
+			SupportedVersions: []uint16{VersionTLS13},
+		}, "signature algorithms"},
+		{pkcs1Cert, &ClientHelloInfo{
+			SignatureSchemes:  []SignatureScheme{PSSWithSHA256, ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS13},
+		}, "signature algorithms"},
+
+		{rsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_RSA_WITH_AES_128_GCM_SHA256},
+			SignatureSchemes:  []SignatureScheme{PKCS1WithSHA1},
+			SupportedVersions: []uint16{VersionTLS13, VersionTLS12},
+		}, "signature algorithms"},
+		{rsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_RSA_WITH_AES_128_GCM_SHA256},
+			SignatureSchemes:  []SignatureScheme{PKCS1WithSHA1},
+			SupportedVersions: []uint16{VersionTLS13, VersionTLS12},
+			config: &Config{
+				MaxVersion: VersionTLS12,
+			},
+		}, ""}, // Check that mutual version selection works.
+
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, ""},
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP384AndSHA384},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, ""}, // TLS 1.2 does not restrict curves based on the SignatureScheme.
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  nil,
+			SupportedVersions: []uint16{VersionTLS12},
+		}, ""}, // TLS 1.2 comes with default signature schemes.
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_RSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, "cipher suite"},
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+			config: &Config{
+				CipherSuites: []uint16{TLS_RSA_WITH_AES_128_GCM_SHA256},
+			},
+		}, "cipher suite"},
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP384},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, "certificate curve"},
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{1},
+			SignatureSchemes:  []SignatureScheme{ECDSAWithP256AndSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, "doesn't support ECDHE"},
+		{ecdsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{PSSWithSHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, "signature algorithms"},
+
+		{ed25519Cert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256}, // only relevant for ECDHE support
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{Ed25519},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, ""},
+		{ed25519Cert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{CurveP256}, // only relevant for ECDHE support
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{Ed25519},
+			SupportedVersions: []uint16{VersionTLS10},
+		}, "doesn't support Ed25519"},
+		{ed25519Cert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256},
+			SupportedCurves:   []CurveID{},
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SignatureSchemes:  []SignatureScheme{Ed25519},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, "doesn't support ECDHE"},
+
+		{rsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA},
+			SupportedCurves:   []CurveID{CurveP256}, // only relevant for ECDHE support
+			SupportedPoints:   []uint8{pointFormatUncompressed},
+			SupportedVersions: []uint16{VersionTLS10},
+		}, ""},
+		{rsaCert, &ClientHelloInfo{
+			CipherSuites:      []uint16{TLS_RSA_WITH_AES_128_GCM_SHA256},
+			SupportedVersions: []uint16{VersionTLS12},
+		}, ""}, // static RSA fallback
+	}
+	for i, tt := range tests {
+		err := tt.chi.SupportsCertificate(tt.c)
+		switch {
+		case tt.wantErr == "" && err != nil:
+			t.Errorf("%d: unexpected error: %v", i, err)
+		case tt.wantErr != "" && err == nil:
+			t.Errorf("%d: unexpected success", i)
+		case tt.wantErr != "" && !strings.Contains(err.Error(), tt.wantErr):
+			t.Errorf("%d: got error %q, expected %q", i, err, tt.wantErr)
+		}
+	}
+}
+
+func TestCipherSuites(t *testing.T) {
+	var lastID uint16
+	for _, c := range CipherSuites() {
+		if lastID > c.ID {
+			t.Errorf("CipherSuites are not ordered by ID: got %#04x after %#04x", c.ID, lastID)
+		} else {
+			lastID = c.ID
+		}
+
+		if c.Insecure {
+			t.Errorf("%#04x: Insecure CipherSuite returned by CipherSuites()", c.ID)
+		}
+	}
+	lastID = 0
+	for _, c := range InsecureCipherSuites() {
+		if lastID > c.ID {
+			t.Errorf("InsecureCipherSuites are not ordered by ID: got %#04x after %#04x", c.ID, lastID)
+		} else {
+			lastID = c.ID
+		}
+
+		if !c.Insecure {
+			t.Errorf("%#04x: not Insecure CipherSuite returned by InsecureCipherSuites()", c.ID)
+		}
+	}
+
+	CipherSuiteByID := func(id uint16) *CipherSuite {
+		for _, c := range CipherSuites() {
+			if c.ID == id {
+				return c
+			}
+		}
+		for _, c := range InsecureCipherSuites() {
+			if c.ID == id {
+				return c
+			}
+		}
+		return nil
+	}
+
+	for _, c := range cipherSuites {
+		cc := CipherSuiteByID(c.id)
+		if cc == nil {
+			t.Errorf("%#04x: no CipherSuite entry", c.id)
+			continue
+		}
+
+		if tls12Only := c.flags&suiteTLS12 != 0; tls12Only && len(cc.SupportedVersions) != 1 {
+			t.Errorf("%#04x: suite is TLS 1.2 only, but SupportedVersions is %v", c.id, cc.SupportedVersions)
+		} else if !tls12Only && len(cc.SupportedVersions) != 3 {
+			t.Errorf("%#04x: suite TLS 1.0-1.2, but SupportedVersions is %v", c.id, cc.SupportedVersions)
+		}
+
+		if got := CipherSuiteName(c.id); got != cc.Name {
+			t.Errorf("%#04x: unexpected CipherSuiteName: got %q, expected %q", c.id, got, cc.Name)
+		}
+	}
+	for _, c := range cipherSuitesTLS13 {
+		cc := CipherSuiteByID(c.id)
+		if cc == nil {
+			t.Errorf("%#04x: no CipherSuite entry", c.id)
+			continue
+		}
+
+		if cc.Insecure {
+			t.Errorf("%#04x: Insecure %v, expected false", c.id, cc.Insecure)
+		}
+		if len(cc.SupportedVersions) != 1 || cc.SupportedVersions[0] != VersionTLS13 {
+			t.Errorf("%#04x: suite is TLS 1.3 only, but SupportedVersions is %v", c.id, cc.SupportedVersions)
+		}
+
+		if got := CipherSuiteName(c.id); got != cc.Name {
+			t.Errorf("%#04x: unexpected CipherSuiteName: got %q, expected %q", c.id, got, cc.Name)
+		}
+	}
+
+	if got := CipherSuiteName(0xabc); got != "0x0ABC" {
+		t.Errorf("unexpected fallback CipherSuiteName: got %q, expected 0x0ABC", got)
+	}
+
+	if len(cipherSuitesPreferenceOrder) != len(cipherSuites) {
+		t.Errorf("cipherSuitesPreferenceOrder is not the same size as cipherSuites")
+	}
+	if len(cipherSuitesPreferenceOrderNoAES) != len(cipherSuitesPreferenceOrder) {
+		t.Errorf("cipherSuitesPreferenceOrderNoAES is not the same size as cipherSuitesPreferenceOrder")
+	}
+
+	// Check that disabled suites are at the end of the preference lists, and
+	// that they are marked insecure.
+	for i, id := range disabledCipherSuites {
+		offset := len(cipherSuitesPreferenceOrder) - len(disabledCipherSuites)
+		if cipherSuitesPreferenceOrder[offset+i] != id {
+			t.Errorf("disabledCipherSuites[%d]: not at the end of cipherSuitesPreferenceOrder", i)
+		}
+		if cipherSuitesPreferenceOrderNoAES[offset+i] != id {
+			t.Errorf("disabledCipherSuites[%d]: not at the end of cipherSuitesPreferenceOrderNoAES", i)
+		}
+		c := CipherSuiteByID(id)
+		if c == nil {
+			t.Errorf("%#04x: no CipherSuite entry", id)
+			continue
+		}
+		if !c.Insecure {
+			t.Errorf("%#04x: disabled by default but not marked insecure", id)
+		}
+	}
+
+	for i, prefOrder := range [][]uint16{cipherSuitesPreferenceOrder, cipherSuitesPreferenceOrderNoAES} {
+		// Check that insecure and HTTP/2 bad cipher suites are at the end of
+		// the preference lists.
+		var sawInsecure, sawBad bool
+		for _, id := range prefOrder {
+			c := CipherSuiteByID(id)
+			if c == nil {
+				t.Errorf("%#04x: no CipherSuite entry", id)
+				continue
+			}
+
+			if c.Insecure {
+				sawInsecure = true
+			} else if sawInsecure {
+				t.Errorf("%#04x: secure suite after insecure one(s)", id)
+			}
+
+			if http2isBadCipher(id) {
+				sawBad = true
+			} else if sawBad {
+				t.Errorf("%#04x: non-bad suite after bad HTTP/2 one(s)", id)
+			}
+		}
+
+		// Check that the list is sorted according to the documented criteria.
+		isBetter := func(a, b int) bool {
+			aSuite, bSuite := cipherSuiteByID(prefOrder[a]), cipherSuiteByID(prefOrder[b])
+			aName, bName := CipherSuiteName(prefOrder[a]), CipherSuiteName(prefOrder[b])
+			// * < RC4
+			if !strings.Contains(aName, "RC4") && strings.Contains(bName, "RC4") {
+				return true
+			} else if strings.Contains(aName, "RC4") && !strings.Contains(bName, "RC4") {
+				return false
+			}
+			// * < CBC_SHA256
+			if !strings.Contains(aName, "CBC_SHA256") && strings.Contains(bName, "CBC_SHA256") {
+				return true
+			} else if strings.Contains(aName, "CBC_SHA256") && !strings.Contains(bName, "CBC_SHA256") {
+				return false
+			}
+			// * < 3DES
+			if !strings.Contains(aName, "3DES") && strings.Contains(bName, "3DES") {
+				return true
+			} else if strings.Contains(aName, "3DES") && !strings.Contains(bName, "3DES") {
+				return false
+			}
+			// ECDHE < *
+			if aSuite.flags&suiteECDHE != 0 && bSuite.flags&suiteECDHE == 0 {
+				return true
+			} else if aSuite.flags&suiteECDHE == 0 && bSuite.flags&suiteECDHE != 0 {
+				return false
+			}
+			// AEAD < CBC
+			if aSuite.aead != nil && bSuite.aead == nil {
+				return true
+			} else if aSuite.aead == nil && bSuite.aead != nil {
+				return false
+			}
+			// AES < ChaCha20
+			if strings.Contains(aName, "AES") && strings.Contains(bName, "CHACHA20") {
+				return i == 0 // true for cipherSuitesPreferenceOrder
+			} else if strings.Contains(aName, "CHACHA20") && strings.Contains(bName, "AES") {
+				return i != 0 // true for cipherSuitesPreferenceOrderNoAES
+			}
+			// AES-128 < AES-256
+			if strings.Contains(aName, "AES_128") && strings.Contains(bName, "AES_256") {
+				return true
+			} else if strings.Contains(aName, "AES_256") && strings.Contains(bName, "AES_128") {
+				return false
+			}
+			// ECDSA < RSA
+			if aSuite.flags&suiteECSign != 0 && bSuite.flags&suiteECSign == 0 {
+				return true
+			} else if aSuite.flags&suiteECSign == 0 && bSuite.flags&suiteECSign != 0 {
+				return false
+			}
+			t.Fatalf("two ciphersuites are equal by all criteria: %v and %v", aName, bName)
+			panic("unreachable")
+		}
+		if !sort.SliceIsSorted(prefOrder, isBetter) {
+			t.Error("preference order is not sorted according to the rules")
+		}
+	}
+}
+
+// http2isBadCipher is copied from net/http.
+// TODO: if it ends up exposed somewhere, use that instead.
+func http2isBadCipher(cipher uint16) bool {
+	switch cipher {
+	case TLS_RSA_WITH_RC4_128_SHA,
+		TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+		TLS_RSA_WITH_AES_128_CBC_SHA,
+		TLS_RSA_WITH_AES_256_CBC_SHA,
+		TLS_RSA_WITH_AES_128_CBC_SHA256,
+		TLS_RSA_WITH_AES_128_GCM_SHA256,
+		TLS_RSA_WITH_AES_256_GCM_SHA384,
+		TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+		TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+		TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+		TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+		TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+		TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+		TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+		TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
+		TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256:
+		return true
+	default:
+		return false
+	}
+}
+
+type brokenSigner struct{ crypto.Signer }
+
+func (s brokenSigner) Sign(rand io.Reader, digest []byte, opts crypto.SignerOpts) (signature []byte, err error) {
+	// Replace opts with opts.HashFunc(), so rsa.PSSOptions are discarded.
+	return s.Signer.Sign(rand, digest, opts.HashFunc())
+}
+
+// TestPKCS1OnlyCert uses a client certificate with a broken crypto.Signer that
+// always makes PKCS #1 v1.5 signatures, so can't be used with RSA-PSS.
+func TestPKCS1OnlyCert(t *testing.T) {
+	clientConfig := testConfig.Clone()
+	clientConfig.Certificates = []Certificate{{
+		Certificate: [][]byte{testRSACertificate},
+		PrivateKey:  brokenSigner{testRSAPrivateKey},
+	}}
+	serverConfig := testConfig.Clone()
+	serverConfig.MaxVersion = VersionTLS12 // TLS 1.3 doesn't support PKCS #1 v1.5
+	serverConfig.ClientAuth = RequireAnyClientCert
+
+	// If RSA-PSS is selected, the handshake should fail.
+	if _, _, err := testHandshake(t, clientConfig, serverConfig); err == nil {
+		t.Fatal("expected broken certificate to cause connection to fail")
+	}
+
+	clientConfig.Certificates[0].SupportedSignatureAlgorithms =
+		[]SignatureScheme{PKCS1WithSHA1, PKCS1WithSHA256}
+
+	// But if the certificate restricts supported algorithms, RSA-PSS should not
+	// be selected, and the handshake should succeed.
+	if _, _, err := testHandshake(t, clientConfig, serverConfig); err != nil {
+		t.Error(err)
+	}
+}