circumvention: add the tor experiment (#100)

* go.mod go.sum: update all non-probe-engine deps

For each line in the go.mod, run `go get -u -v $package` if the
line is not an indirect dependency and is not probe-engine.

Upgrading probe-engine is going to require the same spell that
is used in probe-engine to update psiphon.

* go get -v github.com/ooni/probe-engine@v0.5.0

This just pins to the latest probe-engine but we've not manually
pinned all the other dependencieds yet.

Take care of the trivial API changes in probe-engine as well, such
that we can have a working build after this commit.

* go.mod go.sum: pin to probe-engine dependencies

Basically: remove all indirect dependencies. Merge this go.mod with
the one of probe-engine, to pin dependencies. Run `go mod tidy`.

* circumvention: add basic implementation of tor

This needs to be polished further, of course. But at least we have
now added support for running tor in the circumvention group.

* Readme.md: document how to update dependencies

* go get -v github.com/ooni/probe-engine@fcc9ee0a7afb

* go get -v github.com/ooni/probe-engine@4d254f5b2

* nettests/tor.go: implement summary test keys

nettests/groups.go

@@ -40,6 +40,7 @@ var NettestGroups = map[string]NettestGroup{
 		Label: "Circumvention Tools",
 		Nettests: []Nettest{
 			Psiphon{},
+			Tor{},
 		},
 	},
 }

nettests/tor.go

@@ -0,0 +1,72 @@
+package nettests
+
+// Tor test implementation
+type Tor struct {
+}
+
+// Run starts the test
+func (h Tor) Run(ctl *Controller) error {
+	builder, err := ctl.Ctx.Session.NewExperimentBuilder(
+		"tor",
+	)
+	if err != nil {
+		return err
+	}
+	return ctl.Run(builder, []string{""})
+}
+
+// TorTestKeys contains the test keys
+type TorTestKeys struct {
+	DirPortTotal            int64 `json:"dir_port_total"`
+	DirPortAccessible       int64 `json:"dir_port_accessible"`
+	IsAnomaly               bool  `json:"-"`
+	OBFS4Total              int64 `json:"obfs4_total"`
+	OBFS4Accessible         int64 `json:"obfs4_accessible"`
+	ORPortDirauthTotal      int64 `json:"or_port_dirauth_total"`
+	ORPortDirauthAccessible int64 `json:"or_port_dirauth_accessible"`
+	ORPortTotal             int64 `json:"or_port_total"`
+	ORPortAccessible        int64 `json:"or_port_accessible"`
+}
+
+// GetTestKeys generates a summary for a test run
+func (h Tor) GetTestKeys(tk map[string]interface{}) (interface{}, error) {
+	testKeys := TorTestKeys{IsAnomaly: false}
+	// Implementation note: when Go marshals into an interface, it marshals to
+	// float64 rather than int64, so we need to do some more work here.
+	//
+	// See <https://golang.org/pkg/encoding/json/#Unmarshal>.
+	if tk["dir_port_total"] != nil {
+		testKeys.DirPortTotal = int64(tk["dir_port_total"].(float64))
+	}
+	if tk["dir_port_accessible"] != nil {
+		testKeys.DirPortAccessible = int64(tk["dir_port_accessible"].(float64))
+	}
+	if tk["obfs4_total"] != nil {
+		testKeys.OBFS4Total = int64(tk["obfs4_total"].(float64))
+	}
+	if tk["obfs4_accessible"] != nil {
+		testKeys.OBFS4Accessible = int64(tk["obfs4_accessible"].(float64))
+	}
+	if tk["or_port_dirauth_total"] != nil {
+		testKeys.ORPortDirauthTotal = int64(tk["or_port_dirauth_total"].(float64))
+	}
+	if tk["or_port_dirauth_accessible"] != nil {
+		testKeys.ORPortDirauthAccessible = int64(tk["or_port_dirauth_accessible"].(float64))
+	}
+	if tk["or_port_total"] != nil {
+		testKeys.ORPortTotal = int64(tk["or_port_total"].(float64))
+	}
+	if tk["or_port_accessible"] != nil {
+		testKeys.ORPortAccessible = int64(tk["or_port_accessible"].(float64))
+	}
+	testKeys.IsAnomaly = ((testKeys.DirPortAccessible <= 0 && testKeys.DirPortTotal > 0) ||
+		(testKeys.OBFS4Accessible <= 0 && testKeys.OBFS4Total > 0) ||
+		(testKeys.ORPortDirauthAccessible <= 0 && testKeys.ORPortDirauthTotal > 0) ||
+		(testKeys.ORPortAccessible <= 0 && testKeys.ORPortTotal > 0))
+	return testKeys, nil
+}
+
+// LogSummary writes the summary to the standard output
+func (h Tor) LogSummary(s string) error {
+	return nil
+}

nettests/web_connectivity.go

@@ -10,7 +10,7 @@ func lookupURLs(ctl *Controller, limit int64) ([]string, map[int64]int64, error)
 	var urls []string
 	urlIDMap := make(map[int64]int64)
 	testlist, err := ctl.Ctx.Session.QueryTestListsURLs(&engine.TestListsURLsConfig{
-		Limit: int(limit),
+		Limit: limit,
 	})
 	if err != nil {
 		return nil, nil, err