Bug 1205137 - Add a PushSubscription serializer. r=mt,smaug

dom/push/PushManager.cpp

@@ -6,6 +6,7 @@
 
 #include "mozilla/dom/PushManager.h"
 
+#include "mozilla/Base64.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Services.h"
 #include "mozilla/unused.h"
@@ -65,6 +66,26 @@ GetPermissionState(nsIPrincipal* aPrincipal,
   return NS_OK;
 }
 
+void
+SubscriptionToJSON(PushSubscriptionJSON& aJSON, const nsString& aEndpoint,
+                   const nsTArray<uint8_t>& aRawP256dhKey,
+                   const nsTArray<uint8_t>& aAuthSecret)
+{
+  aJSON.mEndpoint.Construct();
+  aJSON.mEndpoint.Value() = aEndpoint;
+
+  aJSON.mKeys.mP256dh.Construct();
+  nsresult rv = Base64URLEncode(aRawP256dhKey.Length(),
+                                aRawP256dhKey.Elements(),
+                                aJSON.mKeys.mP256dh.Value());
+  Unused << NS_WARN_IF(NS_FAILED(rv));
+
+  aJSON.mKeys.mAuth.Construct();
+  rv = Base64URLEncode(aAuthSecret.Length(), aAuthSecret.Elements(),
+                       aJSON.mKeys.mAuth.Value());
+  Unused << NS_WARN_IF(NS_FAILED(rv));
+}
+
 } // anonymous namespace
 
 class UnsubscribeResultCallback final : public nsIUnsubscribeResultCallback
@@ -123,6 +144,12 @@ PushSubscription::Unsubscribe(ErrorResult& aRv)
   return p.forget();
 }
 
+void
+PushSubscription::ToJSON(PushSubscriptionJSON& aJSON)
+{
+  SubscriptionToJSON(aJSON, mEndpoint, mRawP256dhKey, mAuthSecret);
+}
+
 PushSubscription::PushSubscription(nsIGlobalObject* aGlobal,
                                    const nsAString& aEndpoint,
                                    const nsAString& aScope,
@@ -507,6 +534,12 @@ WorkerPushSubscription::Unsubscribe(ErrorResult &aRv)
   return p.forget();
 }
 
+void
+WorkerPushSubscription::ToJSON(PushSubscriptionJSON& aJSON)
+{
+  SubscriptionToJSON(aJSON, mEndpoint, mRawP256dhKey, mAuthSecret);
+}
+
 NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(WorkerPushSubscription)
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(WorkerPushSubscription)

dom/push/PushManager.h

@@ -104,6 +104,9 @@ public:
   already_AddRefed<Promise>
   Unsubscribe(ErrorResult& aRv);
 
+  void
+  ToJSON(PushSubscriptionJSON& aJSON);
+
 protected:
   ~PushSubscription();
 
@@ -197,6 +200,9 @@ public:
   already_AddRefed<Promise>
   Unsubscribe(ErrorResult& aRv);
 
+  void
+  ToJSON(PushSubscriptionJSON& aJSON);
+
 protected:
   ~WorkerPushSubscription();
 

dom/push/test/test_data.html

@@ -77,6 +77,47 @@ http://creativecommons.org/licenses/publicdomain/
     });
   }
 
+  function base64UrlDecode(s) {
+    s = s.replace(/-/g, '+').replace(/_/g, '/');
+
+    // Replace padding if it was stripped by the sender.
+    // See http://tools.ietf.org/html/rfc4648#section-4
+    switch (s.length % 4) {
+      case 0:
+        break; // No pad chars in this case
+      case 2:
+        s += '==';
+        break; // Two pad chars
+      case 3:
+        s += '=';
+        break; // One pad char
+      default:
+        throw new Error('Illegal base64url string!');
+    }
+
+    // With correct padding restored, apply the standard base64 decoder
+    var decoded = atob(s);
+
+    var array = new Uint8Array(new ArrayBuffer(decoded.length));
+    for (var i = 0; i < decoded.length; i++) {
+      array[i] = decoded.charCodeAt(i);
+    }
+    return array;
+  }
+
+  add_task(function* compareJSONSubscription() {
+    var json = pushSubscription.toJSON();
+    is(json.endpoint, pushSubscription.endpoint, "Wrong endpoint");
+
+    ["p256dh", "auth"].forEach(keyName => {
+      isDeeply(
+        base64UrlDecode(json.keys[keyName]),
+        new Uint8Array(pushSubscription.getKey(keyName)),
+        "Mismatched Base64-encoded key: " + keyName
+      );
+    });
+  });
+
   add_task(function* comparePublicKey() {
     var data = yield sendRequestToWorker({ type: "publicKey" });
     var p256dhKey = new Uint8Array(pushSubscription.getKey("p256dh"));

dom/webidl/PushSubscription.webidl

@@ -15,6 +15,18 @@ enum PushEncryptionKeyName
   "auth"
 };
 
+dictionary PushSubscriptionKeys
+{
+  ByteString p256dh;
+  ByteString auth;
+};
+
+dictionary PushSubscriptionJSON
+{
+  USVString endpoint;
+  PushSubscriptionKeys keys;
+};
+
 [Exposed=(Window,Worker), Func="nsContentUtils::PushEnabled",
  ChromeConstructor(DOMString pushEndpoint, DOMString scope,
                    ArrayBuffer? key, ArrayBuffer? authSecret)]
@@ -24,7 +36,9 @@ interface PushSubscription
     ArrayBuffer? getKey(PushEncryptionKeyName name);
     [Throws, UseCounter]
     Promise<boolean> unsubscribe();
-    jsonifier;
+
+    // Implements the custom serializer specified in Push API, section 9.
+    PushSubscriptionJSON toJSON();
 
     // Used to set the principal from the JS implemented PushManager.
     [Exposed=Window,ChromeOnly]

xpcom/io/Base64.cpp

@@ -225,6 +225,9 @@ EncodeInputStream(nsIInputStream* aInputStream,
   return NS_OK;
 }
 
+static const char kBase64URLAlphabet[] =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+
 } // namespace
 
 namespace mozilla {
@@ -355,4 +358,49 @@ Base64Decode(const nsAString& aBinaryData, nsAString& aString)
   return rv;
 }
 
+nsresult
+Base64URLEncode(uint32_t aLength, const uint8_t* aData, nsACString& aString)
+{
+  // Don't encode empty strings.
+  if (aLength == 0) {
+    aString.Truncate();
+    return NS_OK;
+  }
+
+  // Check for overflow.
+  if ((static_cast<uint64_t>(aLength) * 6 + 7) / 8 > UINT32_MAX) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (!aString.SetLength((aLength * 8 + 5) / 6, fallible)) {
+    aString.Truncate();
+    return NS_ERROR_FAILURE;
+  }
+
+  char* rawBuffer = aString.BeginWriting();
+
+  uint32_t index = 0;
+  for (; index + 3 <= aLength; index += 3) {
+    *rawBuffer++ = kBase64URLAlphabet[aData[index] >> 2];
+    *rawBuffer++ = kBase64URLAlphabet[((aData[index] & 0x3) << 4) |
+                                      (aData[index + 1] >> 4)];
+    *rawBuffer++ = kBase64URLAlphabet[((aData[index + 1] & 0xf) << 2) |
+                                      (aData[index + 2] >> 6)];
+    *rawBuffer++ = kBase64URLAlphabet[aData[index + 2] & 0x3f];
+  }
+
+  uint32_t remaining = aLength - index;
+  if (remaining == 1) {
+    *rawBuffer++ = kBase64URLAlphabet[aData[index] >> 2];
+    *rawBuffer++ = kBase64URLAlphabet[((aData[index] & 0x3) << 4)];
+  } else if (remaining == 2) {
+    *rawBuffer++ = kBase64URLAlphabet[aData[index] >> 2];
+    *rawBuffer++ = kBase64URLAlphabet[((aData[index] & 0x3) << 4) |
+                                      (aData[index + 1] >> 4)];
+    *rawBuffer++ = kBase64URLAlphabet[((aData[index + 1] & 0xf) << 2)];
+  }
+
+  return NS_OK;
+}
+
 } // namespace mozilla

xpcom/io/Base64.h

@@ -34,6 +34,14 @@ Base64Decode(const nsACString& aBinaryData, nsACString& aString);
 nsresult
 Base64Decode(const nsAString& aBinaryData, nsAString& aString);
 
+/**
+ * Converts |aData| to an unpadded, Base64 URL-encoded string per RFC 4648.
+ * Aims to encode the data in constant time. The caller may free |aData| once
+ * this function returns.
+ */
+nsresult
+Base64URLEncode(uint32_t aLength, const uint8_t* aData, nsACString& aString);
+
 } // namespace mozilla
 
 #endif