internal: add mlabns/mlablocate client

internal/mlablocate/mlablocate.go

@@ -0,0 +1,99 @@
+// Package mlablocate contains a locate.measurementlab.net client.
+package mlablocate
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+
+	"github.com/ooni/probe-engine/model"
+)
+
+// NewRequestFunc is the function to create a new request.
+type NewRequestFunc func(ctx context.Context, URL *url.URL) (*http.Request, error)
+
+// Client is a locate.measurementlab.net client.
+type Client struct {
+	HTTPClient *http.Client
+	Hostname   string
+	Logger     model.Logger
+	NewRequest NewRequestFunc
+	Scheme     string
+	UserAgent  string
+}
+
+// NewClient creates a new locate.measurementlab.net client.
+func NewClient(httpClient *http.Client, logger model.Logger, userAgent string) *Client {
+	return &Client{
+		HTTPClient: httpClient,
+		Hostname:   "locate.measurementlab.net",
+		Logger:     logger,
+		NewRequest: NewRequestDefault(),
+		Scheme:     "https",
+		UserAgent:  userAgent,
+	}
+}
+
+// NewRequestDefault return the default implementation of the c.NewRequest
+// for creating a new HTTP request for locate.measurementlab.net.
+func NewRequestDefault() NewRequestFunc {
+	return func(ctx context.Context, URL *url.URL) (*http.Request, error) {
+		return http.NewRequestWithContext(ctx, "GET", URL.String(), nil)
+	}
+}
+
+// NewRequestWithProxy returns a new request factory that tells to the
+// locate.measurementlab.net service that we're using a proxy such that
+// the returned host is good for us, not for the proxy.
+func NewRequestWithProxy(probeIP string) NewRequestFunc {
+	return func(ctx context.Context, URL *url.URL) (*http.Request, error) {
+		values := URL.Query()
+		values.Set("ip", probeIP)
+		URL.RawQuery = values.Encode()
+		return http.NewRequestWithContext(ctx, "GET", URL.String(), nil)
+	}
+}
+
+type locateResult struct {
+	FQDN string `json:"fqdn"`
+}
+
+// Query performs a locate.measurementlab.net query.
+func (c *Client) Query(ctx context.Context, tool string) (string, error) {
+	URL := &url.URL{
+		Scheme: c.Scheme,
+		Host:   c.Hostname,
+		Path:   tool,
+	}
+	req, err := c.NewRequest(ctx, URL)
+	if err != nil {
+		return "", err
+	}
+	req.Header.Add("User-Agent", c.UserAgent)
+	c.Logger.Debugf("mlablocate: GET %s", URL.String())
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		return "", fmt.Errorf("mlablocate: non-200 status code: %d", resp.StatusCode)
+	}
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+	c.Logger.Debugf("mlablocate: %s", string(data))
+	var result locateResult
+	if err := json.Unmarshal(data, &result); err != nil {
+		return "", err
+	}
+	if result.FQDN == "" {
+		return "", errors.New("mlablocate: returned empty FQDN")
+	}
+	return result.FQDN, nil
+}

internal/mlablocate/mlablocate_test.go

@@ -0,0 +1,224 @@
+package mlablocate_test
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/apex/log"
+	"github.com/ooni/probe-engine/internal/mlablocate"
+)
+
+func TestIntegrationWithoutProxy(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	fqdn, err := client.Query(context.Background(), "ndt7")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fqdn == "" {
+		t.Fatal("unexpected empty fqdn")
+	}
+	t.Log(fqdn)
+}
+
+func TestIntegrationWithProxy(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	client.NewRequest = mlablocate.NewRequestWithProxy("8.8.8.8")
+	fqdn, err := client.Query(context.Background(), "ndt7")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if fqdn == "" {
+		t.Fatal("unexpected empty fqdn")
+	}
+	t.Log(fqdn)
+}
+
+func TestIntegration404Response(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if err == nil || !strings.Contains(err.Error(), "mlablocate: non-200 status code") {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+func TestUnitNewRequestFailure(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	client.Hostname = "\t"
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if err == nil || !strings.Contains(err.Error(), "invalid URL escape") {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+func TestUnitHTTPClientDoFailure(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	expected := errors.New("mocked error")
+	client.HTTPClient = &http.Client{
+		Transport: &roundTripFails{Error: expected},
+	}
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if !errors.Is(err, expected) {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+type roundTripFails struct {
+	Error error
+}
+
+func (txp *roundTripFails) RoundTrip(*http.Request) (*http.Response, error) {
+	return nil, txp.Error
+}
+
+func TestUnitCannotReadBody(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	expected := errors.New("mocked error")
+	client.HTTPClient = &http.Client{
+		Transport: &readingBodyFails{Error: expected},
+	}
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if !errors.Is(err, expected) {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+type readingBodyFails struct {
+	Error error
+}
+
+func (txp *readingBodyFails) RoundTrip(*http.Request) (*http.Response, error) {
+	return &http.Response{
+		StatusCode: 200,
+		Body:       &readingBodyFailsBody{Error: txp.Error},
+	}, nil
+}
+
+type readingBodyFailsBody struct {
+	Error error
+}
+
+func (b *readingBodyFailsBody) Read(p []byte) (int, error) {
+	return 0, b.Error
+}
+
+func (b *readingBodyFailsBody) Close() error {
+	return nil
+}
+
+func TestUnitInvalidJSON(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	client.HTTPClient = &http.Client{
+		Transport: &invalidJSON{},
+	}
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if err == nil || !strings.Contains(err.Error(), "unexpected end of JSON input") {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+type invalidJSON struct{}
+
+func (txp *invalidJSON) RoundTrip(*http.Request) (*http.Response, error) {
+	return &http.Response{
+		StatusCode: 200,
+		Body:       &invalidJSONBody{},
+	}, nil
+}
+
+type invalidJSONBody struct{}
+
+func (b *invalidJSONBody) Read(p []byte) (int, error) {
+	if len(p) < 1 {
+		return 0, errors.New("slice too short")
+	}
+	p[0] = '{'
+	return 1, io.EOF
+}
+
+func (b *invalidJSONBody) Close() error {
+	return nil
+}
+
+func TestUnitEmptyFQDN(t *testing.T) {
+	client := mlablocate.NewClient(
+		http.DefaultClient,
+		log.Log,
+		"miniooni/0.1.0-dev",
+	)
+	client.HTTPClient = &http.Client{
+		Transport: &emptyFQDN{},
+	}
+	fqdn, err := client.Query(context.Background(), "nonexistent")
+	if err == nil || !strings.HasSuffix(err.Error(), "returned empty FQDN") {
+		t.Fatal("not the error we expected")
+	}
+	if fqdn != "" {
+		t.Fatal("expected empty fqdn")
+	}
+}
+
+type emptyFQDN struct{}
+
+func (txp *emptyFQDN) RoundTrip(*http.Request) (*http.Response, error) {
+	return &http.Response{
+		StatusCode: 200,
+		Body:       &emptyFQDNBody{},
+	}, nil
+}
+
+type emptyFQDNBody struct{}
+
+func (b *emptyFQDNBody) Read(p []byte) (int, error) {
+	return copy(p, []byte(`{"fqdn":""}`)), io.EOF
+}
+
+func (b *emptyFQDNBody) Close() error {
+	return nil
+}