fix(all): introduce and use iox.ReadAllContext (#379)

* fix(all): introduce and use iox.ReadAllContext

This improvement over the ioutil.ReadAll utility returns early
if the context expires. This enables us to unblock stuck code in
case there's censorship confounding the TCP stack.

See https://github.com/ooni/probe/issues/1417.

Compared to the functionality postulated in the above mentioned
issue, I choose to be more generic and separate limiting the
maximum body size (not implemented here) from using the context
to return early when reading a body (or any other reader).

After implementing iox.ReadAllContext, I made sure we always
use it everywhere in the tree instead of ioutil.ReadAll.

This includes many parts of the codebase where in theory we don't
need iox.ReadAllContext. Though, changing all the places makes
checking whether we're not using ioutil.ReadAll where we should
not be using it easy: `git grep` should return no lines.

* Update internal/iox/iox_test.go

* fix(ndt7): treat context errors as non-errors

The rationale is explained by the comment documenting reduceErr.

* Update internal/engine/experiment/ndt7/download.go

internal/engine/experiment/dash/collect.go

@@ -16,7 +16,7 @@ type collectDeps interface {
 	JSONMarshal(v interface{}) ([]byte, error)
 	Logger() model.Logger
 	NewHTTPRequest(method string, url string, body io.Reader) (*http.Request, error)
-	ReadAll(r io.Reader) ([]byte, error)
+	ReadAllContext(ctx context.Context, r io.Reader) ([]byte, error)
 	Scheme() string
 	UserAgent() string
 }
@@ -47,7 +47,7 @@ func collect(ctx context.Context, fqdn, authorization string,
 		return errHTTPRequestFailed
 	}
 	defer resp.Body.Close()
-	data, err = deps.ReadAll(resp.Body)
+	data, err = deps.ReadAllContext(ctx, resp.Body)
 	if err != nil {
 		return err
 	}

internal/engine/experiment/dash/dash.go

@@ -9,7 +9,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"runtime"
 	"time"
@@ -20,6 +19,7 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
 	"github.com/ooni/probe-cli/v3/internal/humanize"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 const (
@@ -86,8 +86,8 @@ func (r runner) NewHTTPRequest(meth, url string, body io.Reader) (*http.Request,
 	return http.NewRequest(meth, url, body)
 }
 
-func (r runner) ReadAll(reader io.Reader) ([]byte, error) {
-	return ioutil.ReadAll(reader)
+func (r runner) ReadAllContext(ctx context.Context, reader io.Reader) ([]byte, error) {
+	return iox.ReadAllContext(ctx, reader)
 }
 
 func (r runner) Scheme() string {
@@ -179,7 +179,7 @@ func (r runner) measure(
 		current.ConnectTime = connectTime
 		r.tk.ReceiverData = append(r.tk.ReceiverData, current)
 		total += current.Received
-		avgspeed := 8 * float64(total) / time.Now().Sub(begin).Seconds()
+		avgspeed := 8 * float64(total) / time.Since(begin).Seconds()
 		percentage := float64(current.Iteration) / float64(numIterations)
 		message := fmt.Sprintf("streaming: speed: %s", humanize.SI(avgspeed, "bit/s"))
 		r.callbacks.OnProgress(percentage, message)

internal/engine/experiment/dash/download.go

@@ -12,7 +12,7 @@ import (
 type downloadDeps interface {
 	HTTPClient() *http.Client
 	NewHTTPRequest(method string, url string, body io.Reader) (*http.Request, error)
-	ReadAll(r io.Reader) ([]byte, error)
+	ReadAllContext(ctx context.Context, r io.Reader) ([]byte, error)
 	Scheme() string
 	UserAgent() string
 }
@@ -57,7 +57,7 @@ func download(ctx context.Context, config downloadConfig) (downloadResult, error
 		return result, errHTTPRequestFailed
 	}
 	defer resp.Body.Close()
-	data, err := config.deps.ReadAll(resp.Body)
+	data, err := config.deps.ReadAllContext(ctx, resp.Body)
 	if err != nil {
 		return result, err
 	}
@@ -66,7 +66,7 @@ func download(ctx context.Context, config downloadConfig) (downloadResult, error
 	// turns out that Neubot and MK do the same. So, we do what they do. At
 	// the same time, we are currently not able to include the overhead that
 	// is caused by HTTP headers etc. So, we're a bit less precise.
-	result.elapsed = time.Now().Sub(savedTicks).Seconds()
+	result.elapsed = time.Since(savedTicks).Seconds()
 	result.received = int64(len(data))
 	result.requestTicks = savedTicks.Sub(config.begin).Seconds()
 	result.timestamp = time.Now().Unix()

internal/engine/experiment/dash/fake_test.go

@@ -1,6 +1,7 @@
 package dash
 
 import (
+	"context"
 	"io"
 	"net/http"
 	"time"
@@ -36,7 +37,7 @@ func (d FakeDeps) NewHTTPRequest(
 	return d.newHTTPRequestResult, d.newHTTPRequestErr
 }
 
-func (d FakeDeps) ReadAll(r io.Reader) ([]byte, error) {
+func (d FakeDeps) ReadAllContext(ctx context.Context, r io.Reader) ([]byte, error) {
 	return d.readAllResult, d.readAllErr
 }
 

internal/engine/experiment/dash/negotiate.go

@@ -16,7 +16,7 @@ type negotiateDeps interface {
 	JSONMarshal(v interface{}) ([]byte, error)
 	Logger() model.Logger
 	NewHTTPRequest(method string, url string, body io.Reader) (*http.Request, error)
-	ReadAll(r io.Reader) ([]byte, error)
+	ReadAllContext(ctx context.Context, r io.Reader) ([]byte, error)
 	Scheme() string
 	UserAgent() string
 }
@@ -48,7 +48,7 @@ func negotiate(
 		return negotiateResp, errHTTPRequestFailed
 	}
 	defer resp.Body.Close()
-	data, err = deps.ReadAll(resp.Body)
+	data, err = deps.ReadAllContext(ctx, resp.Body)
 	if err != nil {
 		return negotiateResp, err
 	}

internal/engine/experiment/dash/spec.go

@@ -1,12 +1,6 @@
 package dash
 
 const (
-	// currentServerSchemaVersion is the version of the server schema that
-	// will be adopted by this implementation. Version 3 is the one that is
-	// Neubot uses. We needed to bump the version because Web100 is not on
-	// M-Lab anymore and hence we need to make a breaking change.
-	currentServerSchemaVersion = 4
-
 	// negotiatePath is the URL path used to negotiate
 	negotiatePath = "/negotiate/dash"
 

internal/engine/experiment/hhfm/fake_test.go

@@ -2,10 +2,11 @@ package hhfm_test
 
 import (
 	"context"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeDialer struct {
@@ -30,7 +31,7 @@ func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return txp.Func(req)
 	}
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/experiment/hhfm/hhfm.go

@@ -9,7 +9,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"sort"
@@ -21,6 +20,7 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/archival"
 	"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/iox"
 	"github.com/ooni/probe-cli/v3/internal/randx"
 )
 
@@ -198,7 +198,7 @@ func transact(txp Transport, req *http.Request,
 		return nil, nil, urlgetter.ErrHTTPRequestFailed
 	}
 	callbacks.OnProgress(0.75, "reading response body...")
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(req.Context(), resp.Body)
 	callbacks.OnProgress(1.00, fmt.Sprintf("got reseponse body... %+v", err))
 	if err != nil {
 		return nil, nil, err

internal/engine/experiment/ndt7/download.go

@@ -2,11 +2,12 @@ package ndt7
 
 import (
 	"context"
+	"errors"
 	"io"
-	"io/ioutil"
 	"time"
 
 	"github.com/gorilla/websocket"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type downloadManager struct {
@@ -33,6 +34,30 @@ func newDownloadManager(
 }
 
 func (mgr downloadManager) run(ctx context.Context) error {
+	return mgr.reduceErr(mgr.doRun(ctx))
+}
+
+// reduceErr treats as non-errors the errors caused by the context
+// so that we can focus instead on network errors.
+//
+// This function was introduced by https://github.com/ooni/probe-cli/pull/379
+// since before such a PR we did not see context interrupting
+// errors when we were reading messages. Since before such a PR
+// we used to return `nil` on context errors, this function is
+// here to keep the previous behavior by filtering the error
+// returned when reading messages, given that now reading messages
+// can fail midway because we use iox.ReadAllContext.
+func (mgr downloadManager) reduceErr(err error) error {
+	if errors.Is(err, context.Canceled) {
+		return nil
+	}
+	if errors.Is(err, context.DeadlineExceeded) {
+		return nil
+	}
+	return err
+}
+
+func (mgr downloadManager) doRun(ctx context.Context) error {
 	var total int64
 	start := time.Now()
 	if err := mgr.conn.SetReadDeadline(start.Add(mgr.maxRuntime)); err != nil {
@@ -47,7 +72,7 @@ func (mgr downloadManager) run(ctx context.Context) error {
 			return err
 		}
 		if kind == websocket.TextMessage {
-			data, err := ioutil.ReadAll(reader)
+			data, err := iox.ReadAllContext(ctx, reader)
 			if err != nil {
 				return err
 			}
@@ -57,7 +82,7 @@ func (mgr downloadManager) run(ctx context.Context) error {
 			}
 			continue
 		}
-		n, err := io.Copy(ioutil.Discard, reader)
+		n, err := io.Copy(io.Discard, reader)
 		if err != nil {
 			return err
 		}

internal/engine/experiment/ndt7/download_test.go

@@ -143,3 +143,20 @@ type goodJSONReader struct{}
 func (r *goodJSONReader) Read(p []byte) (int, error) {
 	return copy(p, []byte(`{}`)), io.EOF
 }
+
+func TestDownloadReduceErr(t *testing.T) {
+	mgr := downloadManager{}
+	if mgr.reduceErr(context.Canceled) != nil {
+		t.Fatal("reduceErr not working as intended for context.Canceled")
+	}
+	if mgr.reduceErr(context.DeadlineExceeded) != nil {
+		t.Fatal("reduceErr not working as intended for context.DeadlineExceeded")
+	}
+	if mgr.reduceErr(nil) != nil {
+		t.Fatal("reduceErr not working as intended for nil")
+	}
+	expected := errors.New("mocked error")
+	if mgr.reduceErr(expected) != expected {
+		t.Fatal("reduceErr not working as intended for other errors")
+	}
+}

internal/engine/geolocate/fake_test.go

@@ -1,9 +1,10 @@
 package geolocate
 
 import (
-	"io/ioutil"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeTransport struct {
@@ -14,7 +15,7 @@ type FakeTransport struct {
 func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 	time.Sleep(10 * time.Microsecond)
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/httpx/fake_test.go

@@ -1,9 +1,10 @@
 package httpx
 
 import (
-	"io/ioutil"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeTransport struct {
@@ -18,7 +19,7 @@ func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return txp.Func(req)
 	}
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/httpx/jsonapi.go

@@ -7,9 +7,10 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/url"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 // Logger is the definition of Logger used by this package.
@@ -100,7 +101,7 @@ func (c Client) Do(request *http.Request) ([]byte, error) {
 	if response.StatusCode >= 400 {
 		return nil, fmt.Errorf("httpx: request failed: %s", response.Status)
 	}
-	return ioutil.ReadAll(response.Body)
+	return iox.ReadAllContext(request.Context(), response.Body)
 }
 
 // DoJSON performs the provided request and unmarshals the JSON response body

internal/engine/internal/mlablocate/mlablocate.go

@@ -6,11 +6,11 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"net/url"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 // Client is a locate.measurementlab.net client.
@@ -63,7 +63,7 @@ func (c *Client) Query(ctx context.Context, tool string) (Result, error) {
 	if resp.StatusCode != 200 {
 		return Result{}, fmt.Errorf("mlablocate: non-200 status code: %d", resp.StatusCode)
 	}
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(ctx, resp.Body)
 	if err != nil {
 		return Result{}, err
 	}

internal/engine/internal/mlablocatev2/fake_test.go

@@ -1,9 +1,10 @@
 package mlablocatev2
 
 import (
-	"io/ioutil"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeTransport struct {
@@ -18,7 +19,7 @@ func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return txp.Func(req)
 	}
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/internal/mlablocatev2/mlablocatev2.go

@@ -6,12 +6,12 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"net/url"
 	"regexp"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 const (
@@ -102,7 +102,7 @@ func (c Client) query(ctx context.Context, path string) (resultRecord, error) {
 	if resp.StatusCode != 200 {
 		return resultRecord{}, fmt.Errorf("%w: %d", ErrRequestFailed, resp.StatusCode)
 	}
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(ctx, resp.Body)
 	if err != nil {
 		return resultRecord{}, err
 	}

internal/engine/legacy/netx/dialer.go

@@ -135,7 +135,7 @@ func (d *Dialer) SetCABundle(path string) error {
 		return err
 	}
 	pool := x509.NewCertPool()
-	if pool.AppendCertsFromPEM(cert) == false {
+	if !pool.AppendCertsFromPEM(cert) {
 		return errors.New("AppendCertsFromPEM failed")
 	}
 	d.TLSConfig.RootCAs = pool

internal/engine/legacy/netx/http_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"crypto/x509"
 	"errors"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -15,6 +14,7 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func dowithclient(t *testing.T, client *netx.HTTPClient) {
@@ -24,7 +24,7 @@ func dowithclient(t *testing.T, client *netx.HTTPClient) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -126,7 +126,7 @@ func httpProxyTestMain(t *testing.T, client *http.Client, expect int) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/legacy/netx/oldhttptransport/bodytracer.go

@@ -63,7 +63,7 @@ func (bw *bodyWrapper) Read(b []byte) (n int, err error) {
 			// bytes read (0 <= n <= len(p)) and any error encountered."
 			Data:                   b[:n],
 			Error:                  err,
-			DurationSinceBeginning: time.Now().Sub(bw.root.Beginning),
+			DurationSinceBeginning: time.Since(bw.root.Beginning),
 			TransactionID:          bw.tid,
 		},
 	})
@@ -74,7 +74,7 @@ func (bw *bodyWrapper) Close() (err error) {
 	err = bw.ReadCloser.Close()
 	bw.root.Handler.OnMeasurement(modelx.Measurement{
 		HTTPResponseDone: &modelx.HTTPResponseDoneEvent{
-			DurationSinceBeginning: time.Now().Sub(bw.root.Beginning),
+			DurationSinceBeginning: time.Since(bw.root.Beginning),
 			TransactionID:          bw.tid,
 		},
 	})

internal/engine/legacy/netx/oldhttptransport/bodytracer_test.go

@@ -1,9 +1,11 @@
 package oldhttptransport
 
 import (
-	"io/ioutil"
+	"context"
 	"net/http"
 	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestBodyTracerSuccess(t *testing.T) {
@@ -15,7 +17,7 @@ func TestBodyTracerSuccess(t *testing.T) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/legacy/netx/oldhttptransport/httptransport_test.go

@@ -1,9 +1,11 @@
 package oldhttptransport
 
 import (
-	"io/ioutil"
+	"context"
 	"net/http"
 	"testing"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestGood(t *testing.T) {
@@ -15,7 +17,7 @@ func TestGood(t *testing.T) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/legacy/netx/oldhttptransport/tracetripper.go

@@ -2,9 +2,9 @@ package oldhttptransport
 
 import (
 	"bytes"
+	"context"
 	"crypto/tls"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptrace"
 	"sync"
@@ -16,21 +16,22 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/modelx"
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/transactionid"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 // TraceTripper performs single HTTP transactions.
 type TraceTripper struct {
-	readAllErrs  *atomicx.Int64
-	readAll      func(r io.Reader) ([]byte, error)
-	roundTripper http.RoundTripper
+	readAllErrs    *atomicx.Int64
+	readAllContext func(ctx context.Context, r io.Reader) ([]byte, error)
+	roundTripper   http.RoundTripper
 }
 
 // NewTraceTripper creates a new Transport.
 func NewTraceTripper(roundTripper http.RoundTripper) *TraceTripper {
 	return &TraceTripper{
-		readAllErrs:  &atomicx.Int64{},
-		readAll:      ioutil.ReadAll,
-		roundTripper: roundTripper,
+		readAllErrs:    &atomicx.Int64{},
+		readAllContext: iox.ReadAllContext,
+		roundTripper:   roundTripper,
 	}
 }
 
@@ -57,10 +58,10 @@ func (c *readCloseWrapper) Close() error {
 }
 
 func readSnap(
-	source *io.ReadCloser, limit int64,
-	readAll func(r io.Reader) ([]byte, error),
+	ctx context.Context, source *io.ReadCloser, limit int64,
+	readAllContext func(ctx context.Context, r io.Reader) ([]byte, error),
 ) (data []byte, err error) {
-	data, err = readAll(io.LimitReader(*source, limit))
+	data, err = readAllContext(ctx, io.LimitReader(*source, limit))
 	if err == nil {
 		*source = newReadCloseWrapper(
 			io.MultiReader(bytes.NewReader(data), *source),
@@ -79,7 +80,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 	root.Handler.OnMeasurement(modelx.Measurement{
 		HTTPRoundTripStart: &modelx.HTTPRoundTripStartEvent{
 			DialID:                 dialid.ContextDialID(req.Context()),
-			DurationSinceBeginning: time.Now().Sub(root.Beginning),
+			DurationSinceBeginning: time.Since(root.Beginning),
 			Method:                 req.Method,
 			TransactionID:          tid,
 			URL:                    req.URL.String(),
@@ -98,7 +99,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 
 	// Save a snapshot of the request body
 	if req.Body != nil {
-		requestBody, err = readSnap(&req.Body, snapSize, t.readAll)
+		requestBody, err = readSnap(req.Context(), &req.Body, snapSize, t.readAllContext)
 		if err != nil {
 			return nil, err
 		}
@@ -114,7 +115,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 			// configured in the http.Transport
 			root.Handler.OnMeasurement(modelx.Measurement{
 				TLSHandshakeStart: &modelx.TLSHandshakeStartEvent{
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					TransactionID:          tid,
 				},
 			})
@@ -127,7 +128,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 				Operation:     errorx.TLSHandshakeOperation,
 				TransactionID: tid,
 			}.MaybeBuild()
-			durationSinceBeginning := time.Now().Sub(root.Beginning)
+			durationSinceBeginning := time.Since(root.Beginning)
 			// Event emitted by net/http when DialTLS is not
 			// configured in the http.Transport
 			root.Handler.OnMeasurement(modelx.Measurement{
@@ -149,7 +150,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 						info.Conn.LocalAddr().Network(),
 						info.Conn.LocalAddr().String(),
 					),
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					TransactionID:          tid,
 				},
 			})
@@ -165,7 +166,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 			requestHeadersMu.Unlock()
 			root.Handler.OnMeasurement(modelx.Measurement{
 				HTTPRequestHeader: &modelx.HTTPRequestHeaderEvent{
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					Key:                    key,
 					TransactionID:          tid,
 					Value:                  values,
@@ -175,7 +176,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 		WroteHeaders: func() {
 			root.Handler.OnMeasurement(modelx.Measurement{
 				HTTPRequestHeadersDone: &modelx.HTTPRequestHeadersDoneEvent{
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					Headers:                requestHeaders, // [*]
 					Method:                 req.Method,     // [*]
 					TransactionID:          tid,
@@ -193,7 +194,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 			}.MaybeBuild()
 			root.Handler.OnMeasurement(modelx.Measurement{
 				HTTPRequestDone: &modelx.HTTPRequestDoneEvent{
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					Error:                  err,
 					TransactionID:          tid,
 				},
@@ -202,7 +203,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 		GotFirstResponseByte: func() {
 			root.Handler.OnMeasurement(modelx.Measurement{
 				HTTPResponseStart: &modelx.HTTPResponseStartEvent{
-					DurationSinceBeginning: time.Now().Sub(root.Beginning),
+					DurationSinceBeginning: time.Since(root.Beginning),
 					TransactionID:          tid,
 				},
 			})
@@ -233,7 +234,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 	// [*] Require less event joining work by providing info that
 	// makes this event alone actionable for OONI
 	event := &modelx.HTTPRoundTripDoneEvent{
-		DurationSinceBeginning: time.Now().Sub(root.Beginning),
+		DurationSinceBeginning: time.Since(root.Beginning),
 		Error:                  err,
 		RequestBodySnap:        requestBody,
 		RequestHeaders:         requestHeaders,   // [*]
@@ -248,7 +249,7 @@ func (t *TraceTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 		event.ResponseProto = resp.Proto
 		// Save a snapshot of the response body
 		var data []byte
-		data, err = readSnap(&resp.Body, snapSize, t.readAll)
+		data, err = readSnap(req.Context(), &resp.Body, snapSize, t.readAllContext)
 		if err != nil {
 			t.readAllErrs.Add(1)
 			resp = nil // this is how net/http likes it

internal/engine/legacy/netx/oldhttptransport/tracetripper_test.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"errors"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptrace"
 	"sync"
@@ -14,6 +13,7 @@ import (
 
 	"github.com/miekg/dns"
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/modelx"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestTraceTripperSuccess(t *testing.T) {
@@ -25,7 +25,7 @@ func TestTraceTripperSuccess(t *testing.T) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -47,7 +47,7 @@ func (h *roundTripHandler) OnMeasurement(m modelx.Measurement) {
 
 func TestTraceTripperReadAllFailure(t *testing.T) {
 	transport := NewTraceTripper(http.DefaultTransport)
-	transport.readAll = func(r io.Reader) ([]byte, error) {
+	transport.readAllContext = func(ctx context.Context, r io.Reader) ([]byte, error) {
 		return nil, io.EOF
 	}
 	client := &http.Client{Transport: transport}
@@ -156,7 +156,7 @@ func TestTraceTripperWithCorrectSnaps(t *testing.T) {
 
 	// Read the whole response body, parse it as valid DNS
 	// reply and verify we obtained what we expected
-	replyData, err := ioutil.ReadAll(resp.Body)
+	replyData, err := iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -230,7 +230,7 @@ func TestTraceTripperWithReadAllFailingForBody(t *testing.T) {
 	// use such transport to configure an ordinary client
 	transport := NewTraceTripper(http.DefaultTransport)
 	errorMocked := errors.New("mocked error")
-	transport.readAll = func(r io.Reader) ([]byte, error) {
+	transport.readAllContext = func(ctx context.Context, r io.Reader) ([]byte, error) {
 		return nil, errorMocked
 	}
 	const snapSize = 15

internal/engine/legacy/netx/oldhttptransport/transactioner_test.go

@@ -1,11 +1,12 @@
 package oldhttptransport
 
 import (
-	"io/ioutil"
+	"context"
 	"net/http"
 	"testing"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/transactionid"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type transactionerCheckTransactionID struct {
@@ -33,7 +34,7 @@ func TestTransactionerSuccess(t *testing.T) {
 		t.Fatal(err)
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/legacy/netxlogger/netxlogger_test.go

@@ -1,7 +1,7 @@
 package netxlogger
 
 import (
-	"io/ioutil"
+	"context"
 	"net/http"
 	"testing"
 	"time"
@@ -10,6 +10,7 @@ import (
 	"github.com/apex/log/handlers/discard"
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx"
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx/modelx"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestGood(t *testing.T) {
@@ -32,7 +33,7 @@ func TestGood(t *testing.T) {
 		t.Fatal("expected non-nil resp here")
 	}
 	defer resp.Body.Close()
-	_, err = ioutil.ReadAll(resp.Body)
+	_, err = iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/legacy/oonitemplates/oonitemplates.go

@@ -24,6 +24,7 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/legacy/netx"
 	"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/iox"
 	"github.com/ooni/probe-cli/v3/internal/runtimex"
 	"gitlab.com/yawning/obfs4.git/transports"
 	obfs4base "gitlab.com/yawning/obfs4.git/transports/base"
@@ -90,7 +91,7 @@ func (m *connmapper) scramble(cid int64) int64 {
 	// See https://stackoverflow.com/a/38140573/4354461
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	if value, found := m.table[cid]; found == true {
+	if value, found := m.table[cid]; found {
 		return value
 	}
 	var factor int64 = 1
@@ -366,7 +367,7 @@ func HTTPDo(
 				config.MaxResponseBodySnapSize,
 			),
 		)
-		data, err := ioutil.ReadAll(reader)
+		data, err := iox.ReadAllContext(ctx, reader)
 		mu.Lock()
 		results.BodySnap, results.Error = data, err
 		mu.Unlock()

internal/engine/legacy/oonitemplates/oonitemplates_test.go

@@ -377,7 +377,7 @@ type faketransport struct {
 }
 
 func (txp *faketransport) Name() string {
-	return txp.Name()
+	return txp.txp.Name()
 }
 
 func (txp *faketransport) ClientFactory(stateDir string) (obfs4base.ClientFactory, error) {
@@ -385,7 +385,7 @@ func (txp *faketransport) ClientFactory(stateDir string) (obfs4base.ClientFactor
 }
 
 func (txp *faketransport) ServerFactory(stateDir string, args *goptlib.Args) (obfs4base.ServerFactory, error) {
-	return txp.ServerFactory(stateDir, args)
+	return txp.txp.ServerFactory(stateDir, args)
 }
 
 func TestConnmapper(t *testing.T) {

internal/engine/netx/fake_test.go

@@ -2,10 +2,11 @@ package netx
 
 import (
 	"context"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeDialer struct {
@@ -30,7 +31,7 @@ func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return txp.Func(req)
 	}
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/netx/httptransport/bytecounter_test.go

@@ -1,6 +1,7 @@
 package httptransport_test
 
 import (
+	"context"
 	"errors"
 	"io"
 	"io/ioutil"
@@ -10,6 +11,7 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/bytecounter"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/httptransport"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestByteCounterFailure(t *testing.T) {
@@ -68,7 +70,7 @@ func TestByteCounterSuccess(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -104,7 +106,7 @@ func TestByteCounterSuccessWithEOF(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/netx/httptransport/fake_test.go

@@ -2,10 +2,11 @@ package httptransport
 
 import (
 	"context"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type FakeDialer struct {
@@ -30,7 +31,7 @@ func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return txp.Func(req)
 	}
 	if req.Body != nil {
-		ioutil.ReadAll(req.Body)
+		iox.ReadAllContext(req.Context(), req.Body)
 		req.Body.Close()
 	}
 	if txp.Err != nil {

internal/engine/netx/httptransport/logging_test.go

@@ -1,6 +1,7 @@
 package httptransport_test
 
 import (
+	"context"
 	"errors"
 	"io"
 	"io/ioutil"
@@ -11,6 +12,7 @@ import (
 
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/httptransport"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestLoggingFailure(t *testing.T) {
@@ -72,6 +74,6 @@ func TestLoggingSuccess(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	ioutil.ReadAll(resp.Body)
+	iox.ReadAllContext(context.Background(), resp.Body)
 	resp.Body.Close()
 }

internal/engine/netx/httptransport/saver.go

@@ -2,14 +2,15 @@ package httptransport
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptrace"
 	"time"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 // SaverPerformanceHTTPTransport is a RoundTripper that saves
@@ -109,7 +110,7 @@ func (txp SaverBodyHTTPTransport) RoundTrip(req *http.Request) (*http.Response,
 		snapsize = txp.SnapshotSize
 	}
 	if req.Body != nil {
-		data, err := saverSnapRead(req.Body, snapsize)
+		data, err := saverSnapRead(req.Context(), req.Body, snapsize)
 		if err != nil {
 			return nil, err
 		}
@@ -125,7 +126,7 @@ func (txp SaverBodyHTTPTransport) RoundTrip(req *http.Request) (*http.Response,
 	if err != nil {
 		return nil, err
 	}
-	data, err := saverSnapRead(resp.Body, snapsize)
+	data, err := saverSnapRead(req.Context(), resp.Body, snapsize)
 	err = ignoreExpectedEOF(err, resp)
 	if err != nil {
 		resp.Body.Close()
@@ -157,8 +158,8 @@ func ignoreExpectedEOF(err error, resp *http.Response) error {
 	return err
 }
 
-func saverSnapRead(r io.ReadCloser, snapsize int) ([]byte, error) {
-	return ioutil.ReadAll(io.LimitReader(r, int64(snapsize)))
+func saverSnapRead(ctx context.Context, r io.ReadCloser, snapsize int) ([]byte, error) {
+	return iox.ReadAllContext(ctx, io.LimitReader(r, int64(snapsize)))
 }
 
 func saverCompose(data []byte, r io.ReadCloser) io.ReadCloser {

internal/engine/netx/httptransport/saver_test.go

@@ -1,6 +1,7 @@
 package httptransport_test
 
 import (
+	"context"
 	"errors"
 	"io/ioutil"
 	"net/http"
@@ -10,6 +11,7 @@ import (
 
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/httptransport"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestSaverPerformanceNoMultipleEvents(t *testing.T) {
@@ -245,7 +247,7 @@ func TestSaverBodySuccess(t *testing.T) {
 	txp := httptransport.SaverBodyHTTPTransport{
 		RoundTripper: httptransport.FakeTransport{
 			Func: func(req *http.Request) (*http.Response, error) {
-				data, err := ioutil.ReadAll(req.Body)
+				data, err := iox.ReadAllContext(context.Background(), req.Body)
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -274,7 +276,7 @@ func TestSaverBodySuccess(t *testing.T) {
 		t.Fatal("unexpected status code")
 	}
 	defer resp.Body.Close()
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/netx/integration_test.go

@@ -3,7 +3,6 @@ package netx_test
 import (
 	"context"
 	"errors"
-	"io/ioutil"
 	"net/http"
 	"testing"
 
@@ -12,6 +11,7 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/bytecounter"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/errorx"
 	"github.com/ooni/probe-cli/v3/internal/engine/netx/trace"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func TestSuccess(t *testing.T) {
@@ -38,7 +38,7 @@ func TestSuccess(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if _, err = ioutil.ReadAll(resp.Body); err != nil {
+	if _, err = iox.ReadAllContext(context.Background(), resp.Body); err != nil {
 		t.Fatal(err)
 	}
 	if err = resp.Body.Close(); err != nil {

internal/engine/netx/resolver/dnsoverhttps.go

@@ -4,11 +4,11 @@ import (
 	"bytes"
 	"context"
 	"errors"
-	"io/ioutil"
 	"net/http"
 	"time"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/httpheader"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 // DNSOverHTTPS is a DNS over HTTPS RoundTripper. Requests are submitted over
@@ -56,7 +56,7 @@ func (t DNSOverHTTPS) RoundTrip(ctx context.Context, query []byte) ([]byte, erro
 	if resp.Header.Get("content-type") != "application/dns-message" {
 		return nil, errors.New("doh: invalid content-type")
 	}
-	return ioutil.ReadAll(resp.Body)
+	return iox.ReadAllContext(ctx, resp.Body)
 }
 
 // RequiresPadding returns true for DoH according to RFC8467

internal/engine/netx/tlsx/certifi.go

@@ -1,5 +1,5 @@
 // Code generated by go generate; DO NOT EDIT.
-// 2021-06-08 14:36:18.474117 +0200 CEST m=+0.459588210
+// 2021-06-15 10:55:55.638897 +0200 CEST m=+4.257631084
 // https://curl.haxx.se/ca/cacert.pem
 
 package tlsx

internal/engine/netx/tlsx/generate.go

@@ -12,14 +12,16 @@
 package main
 
 import (
+	"context"
 	"crypto/x509"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
 	"strings"
 	"text/template"
 	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 var tmpl = template.Must(template.New("").Parse(`// Code generated by go generate; DO NOT EDIT.
@@ -50,7 +52,7 @@ func main() {
 	}
 	defer resp.Body.Close()
 
-	bundle, err := ioutil.ReadAll(resp.Body)
+	bundle, err := iox.ReadAllContext(context.Background(), resp.Body)
 	if err != nil {
 		log.Fatal(err)
 	}

internal/engine/probeservices/collector_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
 	"github.com/ooni/probe-cli/v3/internal/engine/probeservices"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 type fakeTestKeys struct {
@@ -233,7 +234,7 @@ func TestEndToEnd(t *testing.T) {
 				return
 			}
 			if r.RequestURI == "/report/_id" {
-				data, err := ioutil.ReadAll(r.Body)
+				data, err := iox.ReadAllContext(r.Context(), r.Body)
 				if err != nil {
 					panic(err)
 				}

internal/engine/probeservices/probeservices_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"errors"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"regexp"
 	"strings"
@@ -17,6 +16,7 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
 	"github.com/ooni/probe-cli/v3/internal/engine/probeservices"
 	"github.com/ooni/probe-cli/v3/internal/engine/probeservices/testorchestra"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 func newclient() *probeservices.Client {
@@ -165,7 +165,7 @@ func TestCloudfront(t *testing.T) {
 	if resp.StatusCode != 200 {
 		t.Fatal("unexpected status code")
 	}
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := iox.ReadAllContext(req.Context(), resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}

internal/engine/session_psiphon.go

@@ -6,9 +6,9 @@ import (
 	"bytes"
 	"context"
 	_ "embed"
-	"io/ioutil"
 
 	"filippo.io/age"
+	"github.com/ooni/probe-cli/v3/internal/iox"
 )
 
 //go:embed psiphon-config.json.age
@@ -34,7 +34,7 @@ func (s *sessionTunnelEarlySession) FetchPsiphonConfig(ctx context.Context) ([]b
 	if err != nil {
 		return nil, err
 	}
-	return ioutil.ReadAll(output)
+	return iox.ReadAllContext(ctx, output)
 }
 
 // FetchPsiphonConfig decrypts psiphonConfigJSONAge using