Mask target config on the source detail page (closes #113)

The page rendered the stored target config verbatim, exposing the Slack
incoming-webhook URL, which is a bearer credential: anyone holding it can
post to the channel indefinitely, and it cannot be scoped or revoked
per-holder.

Target config now reaches the template only as a TargetView carrying
labelled fields, so no code path can render the raw blob. maskURL keeps
scheme and host and elides the path, and drops query, fragment and
userinfo; every parse failure yields a neutral placeholder rather than
falling back to the stored string. HTTP header values are never rendered,
only a count.

Rendering change only: the stored config format and the delivery path are
unchanged.

internal/delivery/target_config_view_test.go

@@ -0,0 +1,299 @@
+package delivery_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/delivery"
+)
+
+const (
+	// slackSecretPath is the credential-bearing part of a
+	// Slack incoming webhook URL: everything after the host.
+	slackSecretPath = "/services/T00000000/B00000000/" +
+		"XXXXXXXXXXXXXXXXXXXXXXXX"
+	slackWebhookURL = "https://hooks.slack.com" +
+		slackSecretPath
+
+	viewExampleOrigin = "https://example.com"
+	viewExampleHook   = viewExampleOrigin + "/hook"
+	viewUnavailable   = "(unavailable)"
+	viewExpiryNever   = "never"
+)
+
+func TestMaskedWebhookURL(t *testing.T) {
+	t.Parallel()
+
+	tests := map[string]struct {
+		url  string
+		want string
+	}{
+		"slack webhook": {
+			url:  slackWebhookURL,
+			want: "https://hooks.slack.com/...",
+		},
+		"query string dropped": {
+			url:  viewExampleOrigin + "/a?token=secret",
+			want: viewExampleOrigin + "/...",
+		},
+		// Fabricated userinfo in a test URL, not a real
+		// credential.
+		//nolint:gosec // G101
+		"userinfo dropped": {
+			url:  "https://user:pw@example.com/a/b",
+			want: viewExampleOrigin + "/...",
+		},
+		"no path": {
+			url:  viewExampleOrigin,
+			want: viewExampleOrigin,
+		},
+		"root path": {
+			url:  viewExampleOrigin + "/",
+			want: viewExampleOrigin,
+		},
+		"not a url": {
+			url:  "definitely not a url",
+			want: viewUnavailable,
+		},
+		"empty": {
+			url:  "",
+			want: viewUnavailable,
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			cfg := &delivery.SlackTargetConfig{
+				WebhookURL: tc.url,
+			}
+
+			assert.Equal(
+				t, tc.want, cfg.MaskedWebhookURL(),
+			)
+		})
+	}
+}
+
+// TestMaskedWebhookURL_NeverLeaksPath is the direct
+// expression of the rule: whatever the input, the masked
+// value never contains a path segment of it.
+func TestMaskedWebhookURL_NeverLeaksPath(t *testing.T) {
+	t.Parallel()
+
+	cfg := &delivery.SlackTargetConfig{
+		WebhookURL: slackWebhookURL,
+	}
+
+	masked := cfg.MaskedWebhookURL()
+
+	assert.NotContains(t, masked, "T00000000")
+	assert.NotContains(t, masked, "B00000000")
+	assert.NotContains(
+		t, masked, "XXXXXXXXXXXXXXXXXXXXXXXX",
+	)
+	assert.NotContains(t, masked, slackSecretPath)
+}
+
+// fieldMap turns a view's config fields into a lookup so
+// assertions read by label.
+func fieldMap(fields []delivery.ConfigField) map[string]string {
+	out := make(map[string]string, len(fields))
+	for _, f := range fields {
+		out[f.Label] = f.Value
+	}
+
+	return out
+}
+
+// viewFor projects a single target and returns its view.
+func viewFor(
+	t *testing.T,
+	target database.Target,
+) delivery.TargetView {
+	t.Helper()
+
+	views := delivery.NewTargetViews(
+		[]database.Target{target},
+	)
+	require.Len(t, views, 1)
+
+	return views[0]
+}
+
+func TestNewTargetViews_Slack(t *testing.T) {
+	t.Parallel()
+
+	view := viewFor(t, database.Target{
+		Name:   "slack-target",
+		Type:   database.TargetTypeSlack,
+		Active: true,
+		Config: `{"webhookUrl":"` +
+			slackWebhookURL + `"}`,
+	})
+
+	assert.Equal(t, "slack-target", view.Name)
+	assert.Equal(
+		t,
+		map[string]string{
+			"Webhook URL": "https://hooks.slack.com/...",
+		},
+		fieldMap(view.Config),
+	)
+}
+
+func TestNewTargetViews_HTTP(t *testing.T) {
+	t.Parallel()
+
+	view := viewFor(t, database.Target{
+		Type: database.TargetTypeHTTP,
+		Config: `{"url":"` + viewExampleHook + `",` +
+			`"timeout":30,` +
+			`"headers":{"Authorization":"Bearer sekrit"}}`,
+		MaxRetries:   5,
+		MaxQueueSize: 100,
+	})
+
+	fields := fieldMap(view.Config)
+
+	assert.Equal(
+		t,
+		map[string]string{
+			"Destination URL": viewExampleHook,
+			"Timeout":         "30s",
+			"Headers":         "1 configured",
+			"Max Retries":     "5",
+			"Max Queue Size":  "100",
+		},
+		fields,
+	)
+
+	// Header values can be credentials and are never shown.
+	for _, v := range fields {
+		assert.NotContains(t, v, "sekrit")
+	}
+}
+
+func TestNewTargetViews_HTTPFireAndForget(t *testing.T) {
+	t.Parallel()
+
+	view := viewFor(t, database.Target{
+		Type:   database.TargetTypeHTTP,
+		Config: `{"url":"` + viewExampleHook + `"}`,
+	})
+
+	assert.Equal(
+		t,
+		map[string]string{
+			"Destination URL": viewExampleHook,
+			"Max Retries":     "0 (fire-and-forget)",
+		},
+		fieldMap(view.Config),
+	)
+}
+
+func TestNewTargetViews_Database(t *testing.T) {
+	t.Parallel()
+
+	tests := map[string]struct {
+		config string
+		want   string
+	}{
+		"empty config": {config: "", want: viewExpiryNever},
+		"empty expiry": {config: `{}`, want: viewExpiryNever},
+		"explicit": {
+			config: `{"expiry":"720h"}`,
+			want:   "720h",
+		},
+		"never literal": {
+			config: `{"expiry":"` + viewExpiryNever + `"}`,
+			want:   viewExpiryNever,
+		},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			view := viewFor(t, database.Target{
+				Type:   database.TargetTypeDatabase,
+				Config: tc.config,
+			})
+
+			assert.Equal(
+				t,
+				map[string]string{"Archive Expiry": tc.want},
+				fieldMap(view.Config),
+			)
+		})
+	}
+}
+
+func TestNewTargetViews_Log(t *testing.T) {
+	t.Parallel()
+
+	view := viewFor(t, database.Target{
+		Type:   database.TargetTypeLog,
+		Config: "",
+	})
+
+	assert.Empty(t, view.Config)
+}
+
+// TestNewTargetViews_Unpresentable proves that no config the
+// view cannot present falls back to the stored blob.
+func TestNewTargetViews_Unpresentable(t *testing.T) {
+	t.Parallel()
+
+	const blob = `{"webhookUrl":"https://hooks.slack.com` +
+		slackSecretPath + `"`
+
+	tests := map[string]database.Target{
+		"unknown target type": {
+			Type:   database.TargetType("carrier-pigeon"),
+			Config: blob,
+		},
+		"unparseable json": {
+			Type:   database.TargetTypeSlack,
+			Config: blob,
+		},
+		"empty slack config": {
+			Type: database.TargetTypeSlack,
+		},
+		"slack config without url": {
+			Type:   database.TargetTypeSlack,
+			Config: `{}`,
+		},
+		"unparseable http json": {
+			Type:   database.TargetTypeHTTP,
+			Config: `{"url":`,
+		},
+		"unparseable archive json": {
+			Type:   database.TargetTypeDatabase,
+			Config: `{"expiry":`,
+		},
+		"invalid archive expiry": {
+			Type:   database.TargetTypeDatabase,
+			Config: `{"expiry":"a fortnight"}`,
+		},
+	}
+
+	for name, target := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			view := viewFor(t, target)
+
+			assert.Equal(
+				t,
+				map[string]string{
+					"Configuration": viewUnavailable,
+				},
+				fieldMap(view.Config),
+			)
+		})
+	}
+}