refactor: continue to simplify engine/netx (#769)

The objective of this diff is to simplify the code inside engine/netx
while moving more bits of code inside netxlite.

See ooni/probe#2121

internal/engine/experiment.go

@@ -11,7 +11,6 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/bytecounter"
 	"github.com/ooni/probe-cli/v3/internal/engine/geolocate"
-	"github.com/ooni/probe-cli/v3/internal/engine/netx/httptransport"
 	"github.com/ooni/probe-cli/v3/internal/engine/probeservices"
 	"github.com/ooni/probe-cli/v3/internal/model"
 	"github.com/ooni/probe-cli/v3/internal/version"
@@ -286,7 +285,7 @@ func (e *Experiment) OpenReportContext(ctx context.Context) error {
 	}
 	// use custom client to have proper byte accounting
 	httpClient := &http.Client{
-		Transport: &httptransport.ByteCountingTransport{
+		Transport: &bytecounter.HTTPTransport{
 			HTTPTransport: e.session.httpDefaultTransport, // proxy is OK
 			Counter:       e.byteCounter,
 		},

internal/engine/netx/dialer/dialer.go

@@ -1,8 +1,12 @@
+// Package dialer allows you to create a net.Dialer-compatible
+// DialContext-enabled dialer with error wrapping, optional logging,
+// optional network-events saving, and optional proxying.
 package dialer
 
 import (
 	"net/url"
 
+	"github.com/ooni/probe-cli/v3/internal/bytecounter"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
 	"github.com/ooni/probe-cli/v3/internal/model"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
@@ -63,9 +67,9 @@ func New(config *Config, resolver model.Resolver) model.Dialer {
 		Resolver: resolver,
 		Dialer:   d,
 	}
-	d = &proxyDialer{ProxyURL: config.ProxyURL, Dialer: d}
+	d = &netxlite.MaybeProxyDialer{ProxyURL: config.ProxyURL, Dialer: d}
 	if config.ContextByteCounting {
-		d = &byteCounterDialer{Dialer: d}
+		d = &bytecounter.ContextAwareDialer{Dialer: d}
 	}
 	return d
 }

internal/engine/netx/dialer/dialer_test.go

@@ -1,10 +1,12 @@
 package dialer
 
 import (
+	"net/http"
 	"net/url"
 	"testing"
 
 	"github.com/apex/log"
+	"github.com/ooni/probe-cli/v3/internal/bytecounter"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
 )
@@ -18,11 +20,11 @@ func TestNewCreatesTheExpectedChain(t *testing.T) {
 		ProxyURL:            &url.URL{},
 		ReadWriteSaver:      saver,
 	}, netxlite.DefaultResolver)
-	bcd, ok := dlr.(*byteCounterDialer)
+	bcd, ok := dlr.(*bytecounter.ContextAwareDialer)
 	if !ok {
 		t.Fatal("not a byteCounterDialer")
 	}
-	pd, ok := bcd.Dialer.(*proxyDialer)
+	pd, ok := bcd.Dialer.(*netxlite.MaybeProxyDialer)
 	if !ok {
 		t.Fatal("not a proxyDialer")
 	}
@@ -51,3 +53,18 @@ func TestNewCreatesTheExpectedChain(t *testing.T) {
 		t.Fatal("not a DialerSystem")
 	}
 }
+
+func TestDialerNewSuccess(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skip test in short mode")
+	}
+	log.SetLevel(log.DebugLevel)
+	d := New(&Config{Logger: log.Log}, netxlite.DefaultResolver)
+	txp := &http.Transport{DialContext: d.DialContext}
+	client := &http.Client{Transport: txp}
+	resp, err := client.Get("http://www.google.com")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+}

internal/engine/netx/httptransport/httptransport.go

@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 
 	"github.com/ooni/probe-cli/v3/internal/model"
+	"github.com/ooni/probe-cli/v3/internal/netxlite"
 )
 
 // Config contains the configuration required for constructing an HTTP transport
@@ -14,3 +15,25 @@ type Config struct {
 	TLSDialer  model.TLSDialer
 	TLSConfig  *tls.Config
 }
+
+// NewHTTP3Transport creates a new HTTP3Transport instance.
+//
+// Deprecation warning
+//
+// New code should use netxlite.NewHTTP3Transport instead.
+func NewHTTP3Transport(config Config) model.HTTPTransport {
+	// Rationale for using NoLogger here: previously this code did
+	// not use a logger as well, so it's fine to keep it as is.
+	return netxlite.NewHTTP3Transport(model.DiscardLogger,
+		config.QUICDialer, config.TLSConfig)
+}
+
+// NewSystemTransport creates a new "system" HTTP transport. That is a transport
+// using the Go standard library with custom dialer and TLS dialer.
+//
+// Deprecation warning
+//
+// New code should use netxlite.NewHTTPTransport instead.
+func NewSystemTransport(config Config) model.HTTPTransport {
+	return netxlite.NewOOHTTPBaseTransport(config.Dialer, config.TLSDialer)
+}