refactor(measurexlite): depend on model.MeasuringNetwork (ooni#1260)

With this diff, we detach measurexlite from netxlite. It was already
quite detached through functions used for testing. However, the changes
we implement are allow us to test measurexlite code by changing the
.Netx field of a *Trace, which means we can avoid using netxlite's
singleton for new code.

Another benefit of this diff is that we have clearly spelled out and
packaged into an interface the dependencies required to perform
measurements with measurexlite. Therefore, we can gracefully continue
separating the code used for measuring from the code for contacting the
backend, as detailed in ooni/probe#2531.

internal/measurexlite/dialer.go

@@ -20,7 +20,7 @@ import (
 // except that it returns a model.Dialer that uses this trace.
 func (tx *Trace) NewDialerWithoutResolver(dl model.DebugLogger) model.Dialer {
 	return &dialerTrace{
-		d:  tx.newDialerWithoutResolver(dl),
+		d:  tx.Netx.NewDialerWithoutResolver(dl),
 		tx: tx,
 	}
 }

internal/measurexlite/dialer_test.go

@@ -21,8 +21,10 @@ func TestNewDialerWithoutResolver(t *testing.T) {
 		underlying := &mocks.Dialer{}
 		zeroTime := time.Now()
 		trace := NewTrace(0, zeroTime)
-		trace.newDialerWithoutResolverFn = func(dl model.DebugLogger) model.Dialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewDialerWithoutResolver: func(dl model.DebugLogger, w ...model.DialerWrapper) model.Dialer {
+				return underlying
+			},
 		}
 		dialer := trace.NewDialerWithoutResolver(model.DiscardLogger)
 		dt := dialer.(*dialerTrace)
@@ -46,8 +48,10 @@ func TestNewDialerWithoutResolver(t *testing.T) {
 				return nil, expectedErr
 			},
 		}
-		trace.newDialerWithoutResolverFn = func(dl model.DebugLogger) model.Dialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewDialerWithoutResolver: func(dl model.DebugLogger, w ...model.DialerWrapper) model.Dialer {
+				return underlying
+			},
 		}
 		dialer := trace.NewDialerWithoutResolver(model.DiscardLogger)
 		ctx := context.Background()
@@ -72,8 +76,10 @@ func TestNewDialerWithoutResolver(t *testing.T) {
 				called = true
 			},
 		}
-		trace.newDialerWithoutResolverFn = func(dl model.DebugLogger) model.Dialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewDialerWithoutResolver: func(dl model.DebugLogger, w ...model.DialerWrapper) model.Dialer {
+				return underlying
+			},
 		}
 		dialer := trace.NewDialerWithoutResolver(model.DiscardLogger)
 		dialer.CloseIdleConnections()

internal/measurexlite/dns.go

@@ -93,17 +93,17 @@ func (r *resolverTrace) LookupNS(ctx context.Context, domain string) ([]*net.NS,
 
 // NewStdlibResolver returns a trace-ware system resolver
 func (tx *Trace) NewStdlibResolver(logger model.Logger) model.Resolver {
-	return tx.wrapResolver(tx.newStdlibResolver(logger))
+	return tx.wrapResolver(tx.Netx.NewStdlibResolver(logger))
 }
 
 // NewParallelUDPResolver returns a trace-ware parallel UDP resolver
 func (tx *Trace) NewParallelUDPResolver(logger model.Logger, dialer model.Dialer, address string) model.Resolver {
-	return tx.wrapResolver(tx.newParallelUDPResolver(logger, dialer, address))
+	return tx.wrapResolver(tx.Netx.NewParallelUDPResolver(logger, dialer, address))
 }
 
 // NewParallelDNSOverHTTPSResolver returns a trace-aware parallel DoH resolver
 func (tx *Trace) NewParallelDNSOverHTTPSResolver(logger model.Logger, URL string) model.Resolver {
-	return tx.wrapResolver(tx.newParallelDNSOverHTTPSResolver(logger, URL))
+	return tx.wrapResolver(tx.Netx.NewParallelDNSOverHTTPSResolver(logger, URL))
 }
 
 // OnDNSRoundTripForLookupHost implements model.Trace.OnDNSRoundTripForLookupHost

internal/measurexlite/quic.go

@@ -18,7 +18,7 @@ import (
 // except that it returns a model.QUICDialer that uses this trace.
 func (tx *Trace) NewQUICDialerWithoutResolver(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer {
 	return &quicDialerTrace{
-		qd: tx.newQUICDialerWithoutResolver(listener, dl),
+		qd: tx.Netx.NewQUICDialerWithoutResolver(listener, dl),
 		tx: tx,
 	}
 }

internal/measurexlite/quic_test.go

@@ -23,8 +23,10 @@ func TestNewQUICDialerWithoutResolver(t *testing.T) {
 		underlying := &mocks.QUICDialer{}
 		zeroTime := time.Now()
 		trace := NewTrace(0, zeroTime)
-		trace.newQUICDialerWithoutResolverFn = func(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewQUICDialerWithoutResolver: func(listener model.UDPListener, logger model.DebugLogger, w ...model.QUICDialerWrapper) model.QUICDialer {
+				return underlying
+			},
 		}
 		listener := &mocks.UDPListener{}
 		dialer := trace.NewQUICDialerWithoutResolver(listener, model.DiscardLogger)
@@ -50,8 +52,10 @@ func TestNewQUICDialerWithoutResolver(t *testing.T) {
 				return nil, expectedErr
 			},
 		}
-		trace.newQUICDialerWithoutResolverFn = func(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewQUICDialerWithoutResolver: func(listener model.UDPListener, logger model.DebugLogger, w ...model.QUICDialerWrapper) model.QUICDialer {
+				return underlying
+			},
 		}
 		listener := &mocks.UDPListener{}
 		dialer := trace.NewQUICDialerWithoutResolver(listener, model.DiscardLogger)
@@ -77,8 +81,10 @@ func TestNewQUICDialerWithoutResolver(t *testing.T) {
 				called = true
 			},
 		}
-		trace.newQUICDialerWithoutResolverFn = func(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewQUICDialerWithoutResolver: func(listener model.UDPListener, logger model.DebugLogger, w ...model.QUICDialerWrapper) model.QUICDialer {
+				return underlying
+			},
 		}
 		listener := &mocks.UDPListener{}
 		dialer := trace.NewQUICDialerWithoutResolver(listener, model.DiscardLogger)

internal/measurexlite/tls.go

@@ -20,7 +20,7 @@ import (
 // except that it returns a model.TLSHandshaker that uses this trace.
 func (tx *Trace) NewTLSHandshakerStdlib(dl model.DebugLogger) model.TLSHandshaker {
 	return &tlsHandshakerTrace{
-		thx: tx.newTLSHandshakerStdlib(dl),
+		thx: tx.Netx.NewTLSHandshakerStdlib(dl),
 		tx:  tx,
 	}
 }

internal/measurexlite/tls_test.go

@@ -24,8 +24,10 @@ func TestNewTLSHandshakerStdlib(t *testing.T) {
 		underlying := &mocks.TLSHandshaker{}
 		zeroTime := time.Now()
 		trace := NewTrace(0, zeroTime)
-		trace.newTLSHandshakerStdlibFn = func(dl model.DebugLogger) model.TLSHandshaker {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewTLSHandshakerStdlib: func(logger model.DebugLogger) model.TLSHandshaker {
+				return underlying
+			},
 		}
 		thx := trace.NewTLSHandshakerStdlib(model.DiscardLogger)
 		thxt := thx.(*tlsHandshakerTrace)
@@ -49,8 +51,10 @@ func TestNewTLSHandshakerStdlib(t *testing.T) {
 				return nil, tls.ConnectionState{}, expectedErr
 			},
 		}
-		trace.newTLSHandshakerStdlibFn = func(dl model.DebugLogger) model.TLSHandshaker {
-			return underlying
+		trace.Netx = &mocks.MeasuringNetwork{
+			MockNewTLSHandshakerStdlib: func(logger model.DebugLogger) model.TLSHandshaker {
+				return underlying
+			},
 		}
 		thx := trace.NewTLSHandshakerStdlib(model.DiscardLogger)
 		ctx := context.Background()

internal/measurexlite/trace.go

@@ -10,7 +10,6 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/model"
 	"github.com/ooni/probe-cli/v3/internal/netxlite"
-	utls "gitlab.com/yawning/utls.git"
 )
 
 // Trace implements [model.Trace]. We use a [context.Context] to register ourselves
@@ -31,6 +30,11 @@ type Trace struct {
 	// once you have constructed a trace MAY lead to data races.
 	Index int64
 
+	// Netx is the network to use for measuring. The constructor inits this
+	// field using a [*netxlite.Netx]. You MAY override this field for testing. Make
+	// sure you do that before you start measuring to avoid data races.
+	Netx model.MeasuringNetwork
+
 	// bytesReceivedMap maps a remote host with the bytes we received
 	// from such a remote host. Accessing this map requires one to
 	// additionally hold the bytesReceivedMu mutex.
@@ -40,43 +44,15 @@ type Trace struct {
 	// access from multiple goroutines.
 	bytesReceivedMu *sync.Mutex
 
-	// networkEvent is MANDATORY and buffers network events.
-	networkEvent chan *model.ArchivalNetworkEvent
-
-	// newStdlibResolverFn is OPTIONAL and can be used to overide
-	// calls to the netxlite.NewStdlibResolver factory.
-	newStdlibResolverFn func(logger model.Logger) model.Resolver
-
-	// newParallelUDPResolverFn is OPTIONAL and can be used to overide
-	// calls to the netxlite.NewParallelUDPResolver factory.
-	newParallelUDPResolverFn func(logger model.Logger, dialer model.Dialer, address string) model.Resolver
-
-	// newParallelDNSOverHTTPSResolverFn is OPTIONAL and can be used to overide
-	// calls to the netxlite.NewParallelDNSOverHTTPSUDPResolver factory.
-	newParallelDNSOverHTTPSResolverFn func(logger model.Logger, URL string) model.Resolver
-
-	// newDialerWithoutResolverFn is OPTIONAL and can be used to override
-	// calls to the netxlite.NewDialerWithoutResolver factory.
-	newDialerWithoutResolverFn func(dl model.DebugLogger) model.Dialer
-
-	// newTLSHandshakerStdlibFn is OPTIONAL and can be used to overide
-	// calls to the netxlite.NewTLSHandshakerStdlib factory.
-	newTLSHandshakerStdlibFn func(dl model.DebugLogger) model.TLSHandshaker
-
-	// newTLSHandshakerUTLSFn is OPTIONAL and can be used to overide
-	// calls to the netxlite.NewTLSHandshakerUTLS factory.
-	newTLSHandshakerUTLSFn func(dl model.DebugLogger, id *utls.ClientHelloID) model.TLSHandshaker
-
-	// NewDialerWithoutResolverFn is OPTIONAL and can be used to override
-	// calls to the netxlite.NewQUICDialerWithoutResolver factory.
-	newQUICDialerWithoutResolverFn func(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer
-
 	// dnsLookup is MANDATORY and buffers DNS Lookup observations.
 	dnsLookup chan *model.ArchivalDNSLookupResult
 
 	// delayedDNSResponse is MANDATORY and buffers delayed DNS responses.
 	delayedDNSResponse chan *model.ArchivalDNSLookupResult
 
+	// networkEvent is MANDATORY and buffers network events.
+	networkEvent chan *model.ArchivalNetworkEvent
+
 	// tcpConnect is MANDATORY and buffers TCP connect observations.
 	tcpConnect chan *model.ArchivalTCPConnectResult
 
@@ -134,19 +110,9 @@ const QUICHandshakeBufferSize = 8
 func NewTrace(index int64, zeroTime time.Time, tags ...string) *Trace {
 	return &Trace{
 		Index:            index,
+		Netx:             &netxlite.Netx{Underlying: nil}, // use the host network
 		bytesReceivedMap: make(map[string]int64),
 		bytesReceivedMu:  &sync.Mutex{},
-		networkEvent: make(
-			chan *model.ArchivalNetworkEvent,
-			NetworkEventBufferSize,
-		),
-		newStdlibResolverFn:               nil, // use default
-		newParallelUDPResolverFn:          nil, // use default
-		newParallelDNSOverHTTPSResolverFn: nil, // use default
-		newDialerWithoutResolverFn:        nil, // use default
-		newTLSHandshakerStdlibFn:          nil, // use default
-		newTLSHandshakerUTLSFn:            nil, // use default
-		newQUICDialerWithoutResolverFn:    nil, // use default
 		dnsLookup: make(
 			chan *model.ArchivalDNSLookupResult,
 			DNSLookupBufferSize,
@@ -155,6 +121,10 @@ func NewTrace(index int64, zeroTime time.Time, tags ...string) *Trace {
 			chan *model.ArchivalDNSLookupResult,
 			DelayedDNSResponseBufferSize,
 		),
+		networkEvent: make(
+			chan *model.ArchivalNetworkEvent,
+			NetworkEventBufferSize,
+		),
 		tcpConnect: make(
 			chan *model.ArchivalTCPConnectResult,
 			TCPConnectBufferSize,
@@ -173,69 +143,6 @@ func NewTrace(index int64, zeroTime time.Time, tags ...string) *Trace {
 	}
 }
 
-// newStdlibResolver indirectly calls the passed netxlite.NewStdlibResolver
-// thus allowing us to mock this function for testing
-func (tx *Trace) newStdlibResolver(logger model.Logger) model.Resolver {
-	if tx.newStdlibResolverFn != nil {
-		return tx.newStdlibResolverFn(logger)
-	}
-	return netxlite.NewStdlibResolver(logger)
-}
-
-// newParallelUDPResolver indirectly calls the passed netxlite.NewParallerUDPResolver
-// thus allowing us to mock this function for testing
-func (tx *Trace) newParallelUDPResolver(logger model.Logger, dialer model.Dialer, address string) model.Resolver {
-	if tx.newParallelUDPResolverFn != nil {
-		return tx.newParallelUDPResolverFn(logger, dialer, address)
-	}
-	return netxlite.NewParallelUDPResolver(logger, dialer, address)
-}
-
-// newParallelDNSOverHTTPSResolver indirectly calls the passed netxlite.NewParallerDNSOverHTTPSResolver
-// thus allowing us to mock this function for testing
-func (tx *Trace) newParallelDNSOverHTTPSResolver(logger model.Logger, URL string) model.Resolver {
-	if tx.newParallelDNSOverHTTPSResolverFn != nil {
-		return tx.newParallelDNSOverHTTPSResolverFn(logger, URL)
-	}
-	return netxlite.NewParallelDNSOverHTTPSResolver(logger, URL)
-}
-
-// newDialerWithoutResolver indirectly calls netxlite.NewDialerWithoutResolver
-// thus allowing us to mock this func for testing.
-func (tx *Trace) newDialerWithoutResolver(dl model.DebugLogger) model.Dialer {
-	if tx.newDialerWithoutResolverFn != nil {
-		return tx.newDialerWithoutResolverFn(dl)
-	}
-	return netxlite.NewDialerWithoutResolver(dl)
-}
-
-// newTLSHandshakerStdlib indirectly calls netxlite.NewTLSHandshakerStdlib
-// thus allowing us to mock this func for testing.
-func (tx *Trace) newTLSHandshakerStdlib(dl model.DebugLogger) model.TLSHandshaker {
-	if tx.newTLSHandshakerStdlibFn != nil {
-		return tx.newTLSHandshakerStdlibFn(dl)
-	}
-	return netxlite.NewTLSHandshakerStdlib(dl)
-}
-
-// newTLSHandshakerUTLS indirectly calls netxlite.NewTLSHandshakerUTLS
-// thus allowing us to mock this func for testing.
-func (tx *Trace) newTLSHandshakerUTLS(dl model.DebugLogger, id *utls.ClientHelloID) model.TLSHandshaker {
-	if tx.newTLSHandshakerUTLSFn != nil {
-		return tx.newTLSHandshakerUTLSFn(dl, id)
-	}
-	return netxlite.NewTLSHandshakerUTLS(dl, id)
-}
-
-// newQUICDialerWithoutResolver indirectly calls netxlite.NewQUICDialerWithoutResolver
-// thus allowing us to mock this func for testing.
-func (tx *Trace) newQUICDialerWithoutResolver(listener model.UDPListener, dl model.DebugLogger) model.QUICDialer {
-	if tx.newQUICDialerWithoutResolverFn != nil {
-		return tx.newQUICDialerWithoutResolverFn(listener, dl)
-	}
-	return netxlite.NewQUICDialerWithoutResolver(listener, dl)
-}
-
 // TimeNow implements model.Trace.TimeNow.
 func (tx *Trace) TimeNow() time.Time {
 	if tx.timeNowFn != nil {