refactor(netx): extract tlsdialer from dialer

internal/engine/netx/tlsdialer/eof_test.go

@@ -0,0 +1,80 @@
+package tlsdialer
+
+import (
+	"context"
+	"crypto/tls"
+	"io"
+	"net"
+	"time"
+)
+
+type EOFDialer struct{}
+
+func (EOFDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	time.Sleep(10 * time.Microsecond)
+	return nil, io.EOF
+}
+
+type EOFConnDialer struct{}
+
+func (EOFConnDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	return EOFConn{}, nil
+}
+
+type EOFConn struct {
+	net.Conn
+}
+
+func (EOFConn) Read(p []byte) (int, error) {
+	time.Sleep(10 * time.Microsecond)
+	return 0, io.EOF
+}
+
+func (EOFConn) Write(p []byte) (int, error) {
+	time.Sleep(10 * time.Microsecond)
+	return 0, io.EOF
+}
+
+func (EOFConn) Close() error {
+	time.Sleep(10 * time.Microsecond)
+	return io.EOF
+}
+
+func (EOFConn) LocalAddr() net.Addr {
+	return EOFAddr{}
+}
+
+func (EOFConn) RemoteAddr() net.Addr {
+	return EOFAddr{}
+}
+
+func (EOFConn) SetDeadline(t time.Time) error {
+	return nil
+}
+
+func (EOFConn) SetReadDeadline(t time.Time) error {
+	return nil
+}
+
+func (EOFConn) SetWriteDeadline(t time.Time) error {
+	return nil
+}
+
+type EOFAddr struct{}
+
+func (EOFAddr) Network() string {
+	return "tcp"
+}
+
+func (EOFAddr) String() string {
+	return "127.0.0.1:1234"
+}
+
+type EOFTLSHandshaker struct{}
+
+func (EOFTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	time.Sleep(10 * time.Microsecond)
+	return nil, tls.ConnectionState{}, io.EOF
+}

internal/engine/netx/tlsdialer/fake_test.go

@@ -0,0 +1,71 @@
+package tlsdialer
+
+import (
+	"context"
+	"io"
+	"net"
+	"time"
+)
+
+type FakeDialer struct {
+	Conn net.Conn
+	Err  error
+}
+
+func (d FakeDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	time.Sleep(10 * time.Microsecond)
+	return d.Conn, d.Err
+}
+
+type FakeConn struct {
+	ReadError             error
+	ReadData              []byte
+	SetDeadlineError      error
+	SetReadDeadlineError  error
+	SetWriteDeadlineError error
+	WriteError            error
+}
+
+func (c *FakeConn) Read(b []byte) (int, error) {
+	if len(c.ReadData) > 0 {
+		n := copy(b, c.ReadData)
+		c.ReadData = c.ReadData[n:]
+		return n, nil
+	}
+	if c.ReadError != nil {
+		return 0, c.ReadError
+	}
+	return 0, io.EOF
+}
+
+func (c *FakeConn) Write(b []byte) (n int, err error) {
+	if c.WriteError != nil {
+		return 0, c.WriteError
+	}
+	n = len(b)
+	return
+}
+
+func (*FakeConn) Close() (err error) {
+	return
+}
+
+func (*FakeConn) LocalAddr() net.Addr {
+	return &net.TCPAddr{}
+}
+
+func (*FakeConn) RemoteAddr() net.Addr {
+	return &net.TCPAddr{}
+}
+
+func (c *FakeConn) SetDeadline(t time.Time) (err error) {
+	return c.SetDeadlineError
+}
+
+func (c *FakeConn) SetReadDeadline(t time.Time) (err error) {
+	return c.SetReadDeadlineError
+}
+
+func (c *FakeConn) SetWriteDeadline(t time.Time) (err error) {
+	return c.SetWriteDeadlineError
+}

internal/engine/netx/tlsdialer/integration_test.go

@@ -0,0 +1,36 @@
+package tlsdialer_test
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"testing"
+
+	"github.com/apex/log"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/tlsdialer"
+)
+
+func TestTLSDialerSuccess(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	log.SetLevel(log.DebugLevel)
+	dialer := tlsdialer.TLSDialer{Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.LoggingTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Logger:        log.Log,
+		},
+	}
+	txp := &http.Transport{DialTLS: func(network, address string) (net.Conn, error) {
+		// AlpineLinux edge is still using Go 1.13. We cannot switch to
+		// using DialTLSContext here as we'd like to until either Alpine
+		// switches to Go 1.14 or we drop the MK dependency.
+		return dialer.DialTLSContext(context.Background(), network, address)
+	}}
+	client := &http.Client{Transport: txp}
+	resp, err := client.Get("https://www.google.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+}

internal/engine/netx/tlsdialer/logging.go

@@ -0,0 +1,39 @@
+package tlsdialer
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/internal/tlsx"
+)
+
+// Logger is the logger assumed by this package
+type Logger interface {
+	Debugf(format string, v ...interface{})
+	Debug(message string)
+}
+
+// LoggingTLSHandshaker is a TLSHandshaker with logging
+type LoggingTLSHandshaker struct {
+	TLSHandshaker
+	Logger Logger
+}
+
+// Handshake implements Handshaker.Handshake
+func (h LoggingTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	h.Logger.Debugf("tls {sni=%s next=%+v}...", config.ServerName, config.NextProtos)
+	start := time.Now()
+	tlsconn, state, err := h.TLSHandshaker.Handshake(ctx, conn, config)
+	stop := time.Now()
+	h.Logger.Debugf(
+		"tls {sni=%s next=%+v}... %+v in %s {next=%s cipher=%s v=%s}", config.ServerName,
+		config.NextProtos, err, stop.Sub(start), state.NegotiatedProtocol,
+		tlsx.CipherSuiteString(state.CipherSuite), tlsx.VersionString(state.Version))
+	return tlsconn, state, err
+}
+
+var _ TLSHandshaker = LoggingTLSHandshaker{}

internal/engine/netx/tlsdialer/logging_test.go

@@ -0,0 +1,28 @@
+package tlsdialer_test
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/apex/log"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/tlsdialer"
+)
+
+func TestLoggingTLSHandshakerFailure(t *testing.T) {
+	h := tlsdialer.LoggingTLSHandshaker{
+		TLSHandshaker: tlsdialer.EOFTLSHandshaker{},
+		Logger:        log.Log,
+	}
+	tlsconn, _, err := h.Handshake(context.Background(), tlsdialer.EOFConn{}, &tls.Config{
+		ServerName: "www.google.com",
+	})
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("not the error we expected")
+	}
+	if tlsconn != nil {
+		t.Fatal("expected nil tlsconn here")
+	}
+}

internal/engine/netx/tlsdialer/saver.go

@@ -0,0 +1,49 @@
+package tlsdialer
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/internal/tlsx"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+)
+
+// SaverTLSHandshaker saves events occurring during the handshake
+type SaverTLSHandshaker struct {
+	TLSHandshaker
+	Saver *trace.Saver
+}
+
+// Handshake implements TLSHandshaker.Handshake
+func (h SaverTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	start := time.Now()
+	h.Saver.Write(trace.Event{
+		Name:          "tls_handshake_start",
+		NoTLSVerify:   config.InsecureSkipVerify,
+		TLSNextProtos: config.NextProtos,
+		TLSServerName: config.ServerName,
+		Time:          start,
+	})
+	tlsconn, state, err := h.TLSHandshaker.Handshake(ctx, conn, config)
+	stop := time.Now()
+	h.Saver.Write(trace.Event{
+		Duration:           stop.Sub(start),
+		Err:                err,
+		Name:               "tls_handshake_done",
+		NoTLSVerify:        config.InsecureSkipVerify,
+		TLSCipherSuite:     tlsx.CipherSuiteString(state.CipherSuite),
+		TLSNegotiatedProto: state.NegotiatedProtocol,
+		TLSNextProtos:      config.NextProtos,
+		TLSPeerCerts:       trace.PeerCerts(state, err),
+		TLSServerName:      config.ServerName,
+		TLSVersion:         tlsx.VersionString(state.Version),
+		Time:               stop,
+	})
+	return tlsconn, state, err
+}
+
+var _ TLSHandshaker = SaverTLSHandshaker{}

internal/engine/netx/tlsdialer/saver_test.go

@@ -0,0 +1,313 @@
+package tlsdialer_test
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/dialer"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/tlsdialer"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+)
+
+func TestSaverTLSHandshakerSuccessWithReadWrite(t *testing.T) {
+	// This is the most common use case for collecting reads, writes
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	nextprotos := []string{"h2"}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Config: &tls.Config{NextProtos: nextprotos},
+		Dialer: dialer.SaverConnDialer{
+			Dialer: new(net.Dialer),
+			Saver:  saver,
+		},
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	// Implementation note: we don't close the connection here because it is
+	// very handy to have the last event being the end of the handshake
+	_, err := tlsdlr.DialTLSContext(context.Background(), "tcp", "www.google.com:443")
+	if err != nil {
+		t.Fatal(err)
+	}
+	ev := saver.Read()
+	if len(ev) < 4 {
+		// it's a bit tricky to be sure about the right number of
+		// events because network conditions may influence that
+		t.Fatal("unexpected number of events")
+	}
+	if ev[0].Name != "tls_handshake_start" {
+		t.Fatal("unexpected Name")
+	}
+	if ev[0].TLSServerName != "www.google.com" {
+		t.Fatal("unexpected TLSServerName")
+	}
+	if !reflect.DeepEqual(ev[0].TLSNextProtos, nextprotos) {
+		t.Fatal("unexpected TLSNextProtos")
+	}
+	if ev[0].Time.After(time.Now()) {
+		t.Fatal("unexpected Time")
+	}
+	last := len(ev) - 1
+	for idx := 1; idx < last; idx++ {
+		if ev[idx].Data == nil {
+			t.Fatal("unexpected Data")
+		}
+		if ev[idx].Duration <= 0 {
+			t.Fatal("unexpected Duration")
+		}
+		if ev[idx].Err != nil {
+			t.Fatal("unexpected Err")
+		}
+		if ev[idx].NumBytes <= 0 {
+			t.Fatal("unexpected NumBytes")
+		}
+		switch ev[idx].Name {
+		case errorx.ReadOperation, errorx.WriteOperation:
+		default:
+			t.Fatal("unexpected Name")
+		}
+		if ev[idx].Time.Before(ev[idx-1].Time) {
+			t.Fatal("unexpected Time")
+		}
+	}
+	if ev[last].Duration <= 0 {
+		t.Fatal("unexpected Duration")
+	}
+	if ev[last].Err != nil {
+		t.Fatal("unexpected Err")
+	}
+	if ev[last].Name != "tls_handshake_done" {
+		t.Fatal("unexpected Name")
+	}
+	if ev[last].TLSCipherSuite == "" {
+		t.Fatal("unexpected TLSCipherSuite")
+	}
+	if ev[last].TLSNegotiatedProto != "h2" {
+		t.Fatal("unexpected TLSNegotiatedProto")
+	}
+	if !reflect.DeepEqual(ev[last].TLSNextProtos, nextprotos) {
+		t.Fatal("unexpected TLSNextProtos")
+	}
+	if ev[last].TLSPeerCerts == nil {
+		t.Fatal("unexpected TLSPeerCerts")
+	}
+	if ev[last].TLSServerName != "www.google.com" {
+		t.Fatal("unexpected TLSServerName")
+	}
+	if ev[last].TLSVersion == "" {
+		t.Fatal("unexpected TLSVersion")
+	}
+	if ev[last].Time.Before(ev[last-1].Time) {
+		t.Fatal("unexpected Time")
+	}
+}
+
+func TestSaverTLSHandshakerSuccess(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	nextprotos := []string{"h2"}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Config: &tls.Config{NextProtos: nextprotos},
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	conn, err := tlsdlr.DialTLSContext(context.Background(), "tcp", "www.google.com:443")
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn.Close()
+	ev := saver.Read()
+	if len(ev) != 2 {
+		t.Fatal("unexpected number of events")
+	}
+	if ev[0].Name != "tls_handshake_start" {
+		t.Fatal("unexpected Name")
+	}
+	if ev[0].TLSServerName != "www.google.com" {
+		t.Fatal("unexpected TLSServerName")
+	}
+	if !reflect.DeepEqual(ev[0].TLSNextProtos, nextprotos) {
+		t.Fatal("unexpected TLSNextProtos")
+	}
+	if ev[0].Time.After(time.Now()) {
+		t.Fatal("unexpected Time")
+	}
+	if ev[1].Duration <= 0 {
+		t.Fatal("unexpected Duration")
+	}
+	if ev[1].Err != nil {
+		t.Fatal("unexpected Err")
+	}
+	if ev[1].Name != "tls_handshake_done" {
+		t.Fatal("unexpected Name")
+	}
+	if ev[1].TLSCipherSuite == "" {
+		t.Fatal("unexpected TLSCipherSuite")
+	}
+	if ev[1].TLSNegotiatedProto != "h2" {
+		t.Fatal("unexpected TLSNegotiatedProto")
+	}
+	if !reflect.DeepEqual(ev[1].TLSNextProtos, nextprotos) {
+		t.Fatal("unexpected TLSNextProtos")
+	}
+	if ev[1].TLSPeerCerts == nil {
+		t.Fatal("unexpected TLSPeerCerts")
+	}
+	if ev[1].TLSServerName != "www.google.com" {
+		t.Fatal("unexpected TLSServerName")
+	}
+	if ev[1].TLSVersion == "" {
+		t.Fatal("unexpected TLSVersion")
+	}
+	if ev[1].Time.Before(ev[0].Time) {
+		t.Fatal("unexpected Time")
+	}
+}
+
+func TestSaverTLSHandshakerHostnameError(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	conn, err := tlsdlr.DialTLSContext(
+		context.Background(), "tcp", "wrong.host.badssl.com:443")
+	if err == nil {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("expected nil conn here")
+	}
+	for _, ev := range saver.Read() {
+		if ev.Name != "tls_handshake_done" {
+			continue
+		}
+		if ev.NoTLSVerify == true {
+			t.Fatal("expected NoTLSVerify to be false")
+		}
+		if len(ev.TLSPeerCerts) < 1 {
+			t.Fatal("expected at least a certificate here")
+		}
+	}
+}
+
+func TestSaverTLSHandshakerInvalidCertError(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	conn, err := tlsdlr.DialTLSContext(
+		context.Background(), "tcp", "expired.badssl.com:443")
+	if err == nil {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("expected nil conn here")
+	}
+	for _, ev := range saver.Read() {
+		if ev.Name != "tls_handshake_done" {
+			continue
+		}
+		if ev.NoTLSVerify == true {
+			t.Fatal("expected NoTLSVerify to be false")
+		}
+		if len(ev.TLSPeerCerts) < 1 {
+			t.Fatal("expected at least a certificate here")
+		}
+	}
+}
+
+func TestSaverTLSHandshakerAuthorityError(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	conn, err := tlsdlr.DialTLSContext(
+		context.Background(), "tcp", "self-signed.badssl.com:443")
+	if err == nil {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("expected nil conn here")
+	}
+	for _, ev := range saver.Read() {
+		if ev.Name != "tls_handshake_done" {
+			continue
+		}
+		if ev.NoTLSVerify == true {
+			t.Fatal("expected NoTLSVerify to be false")
+		}
+		if len(ev.TLSPeerCerts) < 1 {
+			t.Fatal("expected at least a certificate here")
+		}
+	}
+}
+
+func TestSaverTLSHandshakerNoTLSVerify(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	saver := &trace.Saver{}
+	tlsdlr := tlsdialer.TLSDialer{
+		Config: &tls.Config{InsecureSkipVerify: true},
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.SaverTLSHandshaker{
+			TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+			Saver:         saver,
+		},
+	}
+	conn, err := tlsdlr.DialTLSContext(
+		context.Background(), "tcp", "self-signed.badssl.com:443")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if conn == nil {
+		t.Fatal("expected non-nil conn here")
+	}
+	conn.Close()
+	for _, ev := range saver.Read() {
+		if ev.Name != "tls_handshake_done" {
+			continue
+		}
+		if ev.NoTLSVerify != true {
+			t.Fatal("expected NoTLSVerify to be true")
+		}
+		if len(ev.TLSPeerCerts) < 1 {
+			t.Fatal("expected at least a certificate here")
+		}
+	}
+}

internal/engine/netx/tlsdialer/tls.go

@@ -0,0 +1,147 @@
+// Package tlsdialer contains code to establish TLS connections.
+package tlsdialer
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/connid"
+	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/modelx"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
+)
+
+// UnderlyingDialer is the underlying dialer type.
+type UnderlyingDialer interface {
+	DialContext(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+// TLSHandshaker is the generic TLS handshaker
+type TLSHandshaker interface {
+	Handshake(ctx context.Context, conn net.Conn, config *tls.Config) (
+		net.Conn, tls.ConnectionState, error)
+}
+
+// SystemTLSHandshaker is the system TLS handshaker.
+type SystemTLSHandshaker struct{}
+
+// Handshake implements Handshaker.Handshake
+func (h SystemTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	tlsconn := tls.Client(conn, config)
+	if err := tlsconn.Handshake(); err != nil {
+		return nil, tls.ConnectionState{}, err
+	}
+	return tlsconn, tlsconn.ConnectionState(), nil
+}
+
+// TimeoutTLSHandshaker is a TLSHandshaker with timeout
+type TimeoutTLSHandshaker struct {
+	TLSHandshaker
+	HandshakeTimeout time.Duration // default: 10 second
+}
+
+// Handshake implements Handshaker.Handshake
+func (h TimeoutTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	timeout := 10 * time.Second
+	if h.HandshakeTimeout != 0 {
+		timeout = h.HandshakeTimeout
+	}
+	if err := conn.SetDeadline(time.Now().Add(timeout)); err != nil {
+		return nil, tls.ConnectionState{}, err
+	}
+	tlsconn, connstate, err := h.TLSHandshaker.Handshake(ctx, conn, config)
+	conn.SetDeadline(time.Time{})
+	return tlsconn, connstate, err
+}
+
+// ErrorWrapperTLSHandshaker wraps the returned error to be an OONI error
+type ErrorWrapperTLSHandshaker struct {
+	TLSHandshaker
+}
+
+// Handshake implements Handshaker.Handshake
+func (h ErrorWrapperTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	connID := connid.Compute(conn.RemoteAddr().Network(), conn.RemoteAddr().String())
+	tlsconn, state, err := h.TLSHandshaker.Handshake(ctx, conn, config)
+	err = errorx.SafeErrWrapperBuilder{
+		ConnID:    connID,
+		Error:     err,
+		Operation: errorx.TLSHandshakeOperation,
+	}.MaybeBuild()
+	return tlsconn, state, err
+}
+
+// EmitterTLSHandshaker emits events using the MeasurementRoot
+type EmitterTLSHandshaker struct {
+	TLSHandshaker
+}
+
+// Handshake implements Handshaker.Handshake
+func (h EmitterTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	connID := connid.Compute(conn.RemoteAddr().Network(), conn.RemoteAddr().String())
+	root := modelx.ContextMeasurementRootOrDefault(ctx)
+	root.Handler.OnMeasurement(modelx.Measurement{
+		TLSHandshakeStart: &modelx.TLSHandshakeStartEvent{
+			ConnID:                 connID,
+			DurationSinceBeginning: time.Now().Sub(root.Beginning),
+			SNI:                    config.ServerName,
+		},
+	})
+	tlsconn, state, err := h.TLSHandshaker.Handshake(ctx, conn, config)
+	root.Handler.OnMeasurement(modelx.Measurement{
+		TLSHandshakeDone: &modelx.TLSHandshakeDoneEvent{
+			ConnID:                 connID,
+			ConnectionState:        modelx.NewTLSConnectionState(state),
+			Error:                  err,
+			DurationSinceBeginning: time.Now().Sub(root.Beginning),
+		},
+	})
+	return tlsconn, state, err
+}
+
+// TLSDialer is the TLS dialer
+type TLSDialer struct {
+	Config        *tls.Config
+	Dialer        UnderlyingDialer
+	TLSHandshaker TLSHandshaker
+}
+
+// DialTLSContext is like tls.DialTLS but with the signature of net.Dialer.DialContext
+func (d TLSDialer) DialTLSContext(ctx context.Context, network, address string) (net.Conn, error) {
+	// Implementation note: when DialTLS is not set, the code in
+	// net/http will perform the handshake. Otherwise, if DialTLS
+	// is set, we will end up here. This code is still used when
+	// performing non-HTTP TLS-enabled dial operations.
+	host, _, err := net.SplitHostPort(address)
+	if err != nil {
+		return nil, err
+	}
+	conn, err := d.Dialer.DialContext(ctx, network, address)
+	if err != nil {
+		return nil, err
+	}
+	config := d.Config
+	if config == nil {
+		config = new(tls.Config)
+	} else {
+		config = config.Clone()
+	}
+	if config.ServerName == "" {
+		config.ServerName = host
+	}
+	tlsconn, _, err := d.TLSHandshaker.Handshake(ctx, conn, config)
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return tlsconn, nil
+}

internal/engine/netx/tlsdialer/tls_test.go

@@ -0,0 +1,277 @@
+package tlsdialer_test
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"io"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/handlers"
+	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/modelx"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
+	"github.com/ooni/probe-cli/v3/internal/engine/netx/tlsdialer"
+)
+
+func TestSystemTLSHandshakerEOFError(t *testing.T) {
+	h := tlsdialer.SystemTLSHandshaker{}
+	conn, _, err := h.Handshake(context.Background(), tlsdialer.EOFConn{}, &tls.Config{
+		ServerName: "x.org",
+	})
+	if err != io.EOF {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+}
+
+func TestTimeoutTLSHandshakerSetDeadlineError(t *testing.T) {
+	h := tlsdialer.TimeoutTLSHandshaker{
+		TLSHandshaker:    tlsdialer.SystemTLSHandshaker{},
+		HandshakeTimeout: 200 * time.Millisecond,
+	}
+	expected := errors.New("mocked error")
+	conn, _, err := h.Handshake(
+		context.Background(), &tlsdialer.FakeConn{SetDeadlineError: expected},
+		new(tls.Config))
+	if !errors.Is(err, expected) {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+}
+
+func TestTimeoutTLSHandshakerEOFError(t *testing.T) {
+	h := tlsdialer.TimeoutTLSHandshaker{
+		TLSHandshaker:    tlsdialer.SystemTLSHandshaker{},
+		HandshakeTimeout: 200 * time.Millisecond,
+	}
+	conn, _, err := h.Handshake(
+		context.Background(), tlsdialer.EOFConn{}, &tls.Config{ServerName: "x.org"})
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+}
+
+func TestTimeoutTLSHandshakerCallsSetDeadline(t *testing.T) {
+	h := tlsdialer.TimeoutTLSHandshaker{
+		TLSHandshaker:    tlsdialer.SystemTLSHandshaker{},
+		HandshakeTimeout: 200 * time.Millisecond,
+	}
+	underlying := &SetDeadlineConn{}
+	conn, _, err := h.Handshake(
+		context.Background(), underlying, &tls.Config{ServerName: "x.org"})
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+	if len(underlying.deadlines) != 2 {
+		t.Fatal("SetDeadline not called twice")
+	}
+	if underlying.deadlines[0].Before(time.Now()) {
+		t.Fatal("the first SetDeadline call was incorrect")
+	}
+	if !underlying.deadlines[1].IsZero() {
+		t.Fatal("the second SetDeadline call was incorrect")
+	}
+}
+
+type SetDeadlineConn struct {
+	tlsdialer.EOFConn
+	deadlines []time.Time
+}
+
+func (c *SetDeadlineConn) SetDeadline(t time.Time) error {
+	c.deadlines = append(c.deadlines, t)
+	return nil
+}
+
+func TestErrorWrapperTLSHandshakerFailure(t *testing.T) {
+	h := tlsdialer.ErrorWrapperTLSHandshaker{TLSHandshaker: tlsdialer.EOFTLSHandshaker{}}
+	conn, _, err := h.Handshake(
+		context.Background(), tlsdialer.EOFConn{}, new(tls.Config))
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+	var errWrapper *errorx.ErrWrapper
+	if !errors.As(err, &errWrapper) {
+		t.Fatal("cannot cast to ErrWrapper")
+	}
+	if errWrapper.ConnID == 0 {
+		t.Fatal("unexpected ConnID")
+	}
+	if errWrapper.Failure != errorx.FailureEOFError {
+		t.Fatal("unexpected Failure")
+	}
+	if errWrapper.Operation != errorx.TLSHandshakeOperation {
+		t.Fatal("unexpected Operation")
+	}
+}
+
+func TestEmitterTLSHandshakerFailure(t *testing.T) {
+	saver := &handlers.SavingHandler{}
+	ctx := modelx.WithMeasurementRoot(context.Background(), &modelx.MeasurementRoot{
+		Beginning: time.Now(),
+		Handler:   saver,
+	})
+	h := tlsdialer.EmitterTLSHandshaker{TLSHandshaker: tlsdialer.EOFTLSHandshaker{}}
+	conn, _, err := h.Handshake(ctx, tlsdialer.EOFConn{}, &tls.Config{
+		ServerName: "www.kernel.org",
+	})
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("expected nil con here")
+	}
+	events := saver.Read()
+	if len(events) != 2 {
+		t.Fatal("Wrong number of events")
+	}
+	if events[0].TLSHandshakeStart == nil {
+		t.Fatal("missing TLSHandshakeStart event")
+	}
+	if events[0].TLSHandshakeStart.ConnID == 0 {
+		t.Fatal("expected nonzero ConnID")
+	}
+	if events[0].TLSHandshakeStart.DurationSinceBeginning == 0 {
+		t.Fatal("expected nonzero DurationSinceBeginning")
+	}
+	if events[0].TLSHandshakeStart.SNI != "www.kernel.org" {
+		t.Fatal("expected nonzero SNI")
+	}
+	if events[1].TLSHandshakeDone == nil {
+		t.Fatal("missing TLSHandshakeDone event")
+	}
+	if events[1].TLSHandshakeDone.ConnID == 0 {
+		t.Fatal("expected nonzero ConnID")
+	}
+	if events[1].TLSHandshakeDone.DurationSinceBeginning == 0 {
+		t.Fatal("expected nonzero DurationSinceBeginning")
+	}
+}
+
+func TestTLSDialerFailureSplitHostPort(t *testing.T) {
+	dialer := tlsdialer.TLSDialer{}
+	conn, err := dialer.DialTLSContext(
+		context.Background(), "tcp", "www.google.com") // missing port
+	if err == nil {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("connection is not nil")
+	}
+}
+
+func TestTLSDialerFailureDialing(t *testing.T) {
+	dialer := tlsdialer.TLSDialer{Dialer: tlsdialer.EOFDialer{}}
+	conn, err := dialer.DialTLSContext(
+		context.Background(), "tcp", "www.google.com:443")
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("connection is not nil")
+	}
+}
+
+func TestTLSDialerFailureHandshaking(t *testing.T) {
+	rec := &RecorderTLSHandshaker{TLSHandshaker: tlsdialer.SystemTLSHandshaker{}}
+	dialer := tlsdialer.TLSDialer{
+		Dialer:        tlsdialer.EOFConnDialer{},
+		TLSHandshaker: rec,
+	}
+	conn, err := dialer.DialTLSContext(
+		context.Background(), "tcp", "www.google.com:443")
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("connection is not nil")
+	}
+	if rec.SNI != "www.google.com" {
+		t.Fatal("unexpected SNI value")
+	}
+}
+
+func TestTLSDialerFailureHandshakingOverrideSNI(t *testing.T) {
+	rec := &RecorderTLSHandshaker{TLSHandshaker: tlsdialer.SystemTLSHandshaker{}}
+	dialer := tlsdialer.TLSDialer{
+		Config: &tls.Config{
+			ServerName: "x.org",
+		},
+		Dialer:        tlsdialer.EOFConnDialer{},
+		TLSHandshaker: rec,
+	}
+	conn, err := dialer.DialTLSContext(
+		context.Background(), "tcp", "www.google.com:443")
+	if !errors.Is(err, io.EOF) {
+		t.Fatal("expected an error here")
+	}
+	if conn != nil {
+		t.Fatal("connection is not nil")
+	}
+	if rec.SNI != "x.org" {
+		t.Fatal("unexpected SNI value")
+	}
+}
+
+type RecorderTLSHandshaker struct {
+	tlsdialer.TLSHandshaker
+	SNI string
+}
+
+func (h *RecorderTLSHandshaker) Handshake(
+	ctx context.Context, conn net.Conn, config *tls.Config,
+) (net.Conn, tls.ConnectionState, error) {
+	h.SNI = config.ServerName
+	return h.TLSHandshaker.Handshake(ctx, conn, config)
+}
+
+func TestDialTLSContextGood(t *testing.T) {
+	dialer := tlsdialer.TLSDialer{
+		Config:        &tls.Config{ServerName: "google.com"},
+		Dialer:        new(net.Dialer),
+		TLSHandshaker: tlsdialer.SystemTLSHandshaker{},
+	}
+	conn, err := dialer.DialTLSContext(context.Background(), "tcp", "google.com:443")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if conn == nil {
+		t.Fatal("connection is nil")
+	}
+	conn.Close()
+}
+
+func TestDialTLSContextTimeout(t *testing.T) {
+	dialer := tlsdialer.TLSDialer{
+		Config: &tls.Config{ServerName: "google.com"},
+		Dialer: new(net.Dialer),
+		TLSHandshaker: tlsdialer.ErrorWrapperTLSHandshaker{
+			TLSHandshaker: tlsdialer.TimeoutTLSHandshaker{
+				TLSHandshaker:    tlsdialer.SystemTLSHandshaker{},
+				HandshakeTimeout: 10 * time.Microsecond,
+			},
+		},
+	}
+	conn, err := dialer.DialTLSContext(context.Background(), "tcp", "google.com:443")
+	if err.Error() != errorx.FailureGenericTimeoutError {
+		t.Fatal("not the error that we expected")
+	}
+	if conn != nil {
+		t.Fatal("connection is not nil")
+	}
+}