session: add privacy preserving geolocation accessors

The previous diff (#963) has
introduced the concept of an accessor for the resolver IP whose returned
value changes depending on the configured privacy settings.

This is a good programming practice. So, while I am slowly approaching to
the bottom of ooni/explorer#495, I though it was
good yak shaving to implement accessors for every variable for which the
configured privacy settings matter.

generate.go

@@ -0,0 +1,181 @@
+// +build ignore
+
+package main
+
+import (
+	"log"
+	"os"
+	"text/template"
+)
+
+var codeTemplate = template.Must(template.New("code").Parse(`
+// Maybe{{ .Name }} is like {{ .Name }} except that we return the real
+// value only if the privacy settings allows us. Otherwise, we just
+// return the default value, model.Default{{ .Name }}.
+func (s *Session) Maybe{{ .Name }}() {{ .Type }} {
+	out := model.Default{{ .Name }}
+	if s.privacySettings.{{ .Setting }} {
+		out = s.{{ .Name }}()
+	}
+	return out
+}`))
+
+var testTemplate = template.Must(template.New("test").Parse(`
+func Test{{ .Name }}Works(t *testing.T) {
+	sess := &Session{location: &model.LocationInfo{
+		{{ .LocationInfoName }}: {{ .LocationInfoValue }},
+	}}
+	t.Run("with false setting", func(t *testing.T) {
+		sess.privacySettings.{{ .Setting }} = false
+		out := sess.Maybe{{ .Name }}()
+		if out != model.Default{{ .Name }} {
+			t.Fatal("not the value we expected")
+		}
+	})
+	t.Run("with true setting", func(t *testing.T) {
+		sess.privacySettings.{{ .Setting }} = true
+		out := sess.Maybe{{ .Name }}()
+		if out != {{ .ValueForTesting }} {
+			t.Fatal("not the value we expected")
+		}
+	})
+}`))
+
+type Variable struct {
+	LocationInfoName  string
+	LocationInfoValue string
+	Name              string
+	Setting           string
+	Type              string
+	ValueForTesting   string
+}
+
+var Variables = []Variable{{
+	LocationInfoName:  "ProbeIP",
+	LocationInfoValue: `"8.8.8.8"`,
+	Name:              "ProbeIP",
+	Setting:           "IncludeIP",
+	Type:              "string",
+	ValueForTesting:   `"8.8.8.8"`,
+}, {
+	LocationInfoName:  "ASN",
+	LocationInfoValue: `30722`,
+	Name:              "ProbeASN",
+	Setting:           "IncludeASN",
+	Type:              "uint",
+	ValueForTesting:   `30722`,
+}, {
+	LocationInfoName:  "ASN",
+	LocationInfoValue: `30722`,
+	Name:              "ProbeASNString",
+	Setting:           "IncludeASN",
+	Type:              "string",
+	ValueForTesting:   `"AS30722"`,
+}, {
+	LocationInfoName:  "CountryCode",
+	LocationInfoValue: `"IT"`,
+	Name:              "ProbeCC",
+	Setting:           "IncludeCountry",
+	Type:              "string",
+	ValueForTesting:   `"IT"`,
+}, {
+	LocationInfoName:  "NetworkName",
+	LocationInfoValue: `"Vodafone Italia"`,
+	Name:              "ProbeNetworkName",
+	Setting:           "IncludeASN",
+	Type:              "string",
+	ValueForTesting:   `"Vodafone Italia"`,
+}, {
+	LocationInfoName:  "ResolverIP",
+	LocationInfoValue: `"9.9.9.9"`,
+	Name:              "ResolverIP",
+	Setting:           "IncludeIP",
+	Type:              "string",
+	ValueForTesting:   `"9.9.9.9"`,
+}, {
+	LocationInfoName:  "ResolverASN",
+	LocationInfoValue: `44`,
+	Name:              "ResolverASN",
+	Setting:           "IncludeASN",
+	Type:              "uint",
+	ValueForTesting:   `44`,
+}, {
+	LocationInfoName:  "ResolverASN",
+	LocationInfoValue: `44`,
+	Name:              "ResolverASNString",
+	Setting:           "IncludeASN",
+	Type:              "string",
+	ValueForTesting:   `"AS44"`,
+}, {
+	LocationInfoName:  "ResolverNetworkName",
+	LocationInfoValue: `"Google LLC"`,
+	Name:              "ResolverNetworkName",
+	Setting:           "IncludeASN",
+	Type:              "string",
+	ValueForTesting:   `"Google LLC"`,
+}}
+
+func writestring(fp *os.File, s string) {
+	if _, err := fp.Write([]byte(s)); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func writeSessionGeneratedGo() {
+	fp, err := os.Create("session_generated.go")
+	if err != nil {
+		log.Fatal(err)
+	}
+	writestring(fp, "// Code generated by go generate; DO NOT EDIT.\n")
+	writestring(fp, "\n")
+	writestring(fp, "package engine\n")
+	writestring(fp, "\n")
+	writestring(fp, "import \"github.com/ooni/probe-engine/model\"\n")
+	writestring(fp, "\n")
+	writestring(fp, "//go:generate go run generate.go")
+	writestring(fp, "\n")
+	for _, variable := range Variables {
+		err := codeTemplate.Execute(fp, variable)
+		if err != nil {
+			log.Fatal(err)
+		}
+		writestring(fp, "\n")
+	}
+	if err := fp.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func writeSessionGeneratedTestGo() {
+	fp, err := os.Create("session_generated_test.go")
+	if err != nil {
+		log.Fatal(err)
+	}
+	writestring(fp, "// Code generated by go generate; DO NOT EDIT.\n")
+	writestring(fp, "\n")
+	writestring(fp, "package engine\n")
+	writestring(fp, "\n")
+	writestring(fp, "import (\n")
+	writestring(fp, "\t\"testing\"\n")
+	writestring(fp, "\n")
+	writestring(fp, "\t\"github.com/ooni/probe-engine/model\"\n")
+	writestring(fp, ")\n")
+	writestring(fp, "\n")
+	writestring(fp, "//go:generate go run generate.go")
+	writestring(fp, "\n")
+	for _, variable := range Variables {
+		err := testTemplate.Execute(fp, variable)
+		if err != nil {
+			log.Fatal(err)
+		}
+		writestring(fp, "\n")
+	}
+	if err := fp.Close(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func main() {
+	writeSessionGeneratedGo()
+	writeSessionGeneratedTestGo()
+}

netx/gocertifi/generate.go

@@ -76,7 +76,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	tmpl.Execute(fp, struct {
+	err = tmpl.Execute(fp, struct {
 		Timestamp time.Time
 		URL       string
 		Bundle    string
@@ -85,6 +85,9 @@ func main() {
 		URL:       url,
 		Bundle:    string(bundle),
 	})
+	if err != nil {
+		log.Fatal(err)
+	}
 
 	if err := fp.Close(); err != nil {
 		log.Fatal(err)

session.go

@@ -193,16 +193,6 @@ func (s *Session) MaybeLookupBackends() error {
 	return s.maybeLookupBackends(context.Background())
 }
 
-// MaybeResolverIP returns the resolver IP, if we have been given the
-// permission to share IPs. Otherwise it returns a canary value.
-func (s *Session) MaybeResolverIP() string {
-	ip := model.DefaultResolverIP
-	if s.privacySettings.IncludeIP {
-		ip = s.ResolverIP()
-	}
-	return ip
-}
-
 // ErrAlreadyUsingProxy indicates that we cannot create a tunnel with
 // a specific name because we already configured a proxy.
 var ErrAlreadyUsingProxy = errors.New(