refactor: move tls handshaker to netxlite (#400)

Part of https://github.com/ooni/probe/issues/1505

internal/netxlite/tlshandshaker_test.go

@@ -0,0 +1,81 @@
+package netxlite
+
+import (
+	"context"
+	"crypto/tls"
+	"io"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/netxmocks"
+)
+
+func TestTLSHandshakerStdlibWithError(t *testing.T) {
+	var times []time.Time
+	h := &TLSHandshakerStdlib{}
+	tcpConn := &netxmocks.Conn{
+		MockWrite: func(b []byte) (int, error) {
+			return 0, io.EOF
+		},
+		MockSetDeadline: func(t time.Time) error {
+			times = append(times, t)
+			return nil
+		},
+	}
+	ctx := context.Background()
+	conn, _, err := h.Handshake(ctx, tcpConn, &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")
+	}
+	if len(times) != 2 {
+		t.Fatal("expected two time entries")
+	}
+	if !times[0].After(time.Now()) {
+		t.Fatal("timeout not in the future")
+	}
+	if !times[1].IsZero() {
+		t.Fatal("did not clear timeout on exit")
+	}
+}
+
+func TestTLSHandshakerStdlibSuccess(t *testing.T) {
+	handler := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		rw.WriteHeader(200)
+	})
+	srvr := httptest.NewTLSServer(handler)
+	defer srvr.Close()
+	URL, err := url.Parse(srvr.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conn, err := net.Dial("tcp", URL.Host)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+	handshaker := &TLSHandshakerStdlib{}
+	ctx := context.Background()
+	config := &tls.Config{
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS13,
+		MaxVersion:         tls.VersionTLS13,
+		ServerName:         URL.Hostname(),
+	}
+	tlsConn, connState, err := handshaker.Handshake(ctx, conn, config)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer tlsConn.Close()
+	if connState.Version != tls.VersionTLS13 {
+		t.Fatal("unexpected TLS version")
+	}
+}