Bug 1657260 - ensure we register with a valid FxA device name. r=rfkelly

Differential Revision: https://phabricator.services.mozilla.com/D87837

services/fxaccounts/FxAccountsDevice.jsm

@@ -40,6 +40,21 @@ XPCOMUtils.defineLazyPreferenceGetter(
 
 const PREF_DEPRECATED_DEVICE_NAME = "services.sync.client.name";
 
+// Sanitizes all characters which the FxA server considers invalid, replacing
+// them with the unicode replacement character.
+// At time of writing, FxA has a regex DISPLAY_SAFE_UNICODE_WITH_NON_BMP, which
+// the regex below is based on.
+// eslint-disable-next-line no-control-regex
+const INVALID_NAME_CHARS = /[\u0000-\u001F\u007F\u0080-\u009F\u2028-\u2029\uE000-\uF8FF\uFFF9-\uFFFC\uFFFE-\uFFFF]/g;
+const MAX_NAME_LEN = 255;
+const REPLACEMENT_CHAR = "\uFFFD";
+
+function sanitizeDeviceName(name) {
+  return name
+    .substr(0, MAX_NAME_LEN)
+    .replace(INVALID_NAME_CHARS, REPLACEMENT_CHAR);
+}
+
 // Everything to do with FxA devices.
 class FxAccountsDevice {
   constructor(fxai) {
@@ -125,11 +140,13 @@ class FxAccountsDevice {
     let syncStrings = Services.strings.createBundle(
       "chrome://weave/locale/sync.properties"
     );
-    return syncStrings.formatStringFromName("client.name2", [
-      user,
-      brandName,
-      system,
-    ]);
+    return sanitizeDeviceName(
+      syncStrings.formatStringFromName("client.name2", [
+        user,
+        brandName,
+        system,
+      ])
+    );
   }
 
   getLocalName() {
@@ -148,12 +165,17 @@ class FxAccountsDevice {
       name = this.getDefaultLocalName();
       Services.prefs.setStringPref(PREF_LOCAL_DEVICE_NAME, name);
     }
-    return name;
+    // We need to sanitize here because some names were generated before we
+    // started sanitizing.
+    return sanitizeDeviceName(name);
   }
 
   setLocalName(newName) {
     Services.prefs.clearUserPref(PREF_DEPRECATED_DEVICE_NAME);
-    Services.prefs.setStringPref(PREF_LOCAL_DEVICE_NAME, newName);
+    Services.prefs.setStringPref(
+      PREF_LOCAL_DEVICE_NAME,
+      sanitizeDeviceName(newName)
+    );
     // Update the registration in the background.
     this.updateDeviceRegistration().catch(error => {
       log.warn("failed to update fxa device registration", error);

services/fxaccounts/tests/xpcshell/test_device.js

@@ -90,3 +90,27 @@ add_task(async function test_reset() {
   await fxAccounts.signOut(/* localOnly = */ true);
   ok(!Services.prefs.prefHasUserValue(namePref));
 });
+
+add_task(async function test_name_sanitization() {
+  fxAccounts.device.setLocalName("emoji is valid \u2665");
+  Assert.equal(fxAccounts.device.getLocalName(), "emoji is valid \u2665");
+
+  let invalid = "x\uFFFD\n\r\t" + "x".repeat(255);
+  let sanitized = "x\uFFFD\uFFFD\uFFFD\uFFFD" + "x".repeat(250); // 255 total.
+
+  // If the pref already has the invalid value we still get the valid one back.
+  Services.prefs.setStringPref(
+    "identity.fxaccounts.account.device.name",
+    invalid
+  );
+  Assert.equal(fxAccounts.device.getLocalName(), sanitized);
+
+  // But if we explicitly set it to an invalid name, the sanitized value ends
+  // up in the pref.
+  fxAccounts.device.setLocalName(invalid);
+  Assert.equal(fxAccounts.device.getLocalName(), sanitized);
+  Assert.equal(
+    Services.prefs.getStringPref("identity.fxaccounts.account.device.name"),
+    sanitized
+  );
+});