Bug 911384 - Follow-up: tolerate explicitly falsy payloads in computeHAWK. r=rnewman

services/crypto/modules/utils.js

@@ -458,7 +458,9 @@ this.CryptoUtils = {
 
     let contentType = CryptoUtils.stripHeaderAttributes(options.contentType);
 
-    if (!artifacts.hash && options.hasOwnProperty("payload")) {
+    if (!artifacts.hash &&
+        options.hasOwnProperty("payload") &&
+        options.payload) {
       let hasher = Cc["@mozilla.org/security/hash;1"]
                      .createInstance(Ci.nsICryptoHash);
       hasher.init(hash_algo);

services/crypto/tests/unit/test_utils_hawk.js

@@ -188,6 +188,16 @@ add_test(function test_hawk() {
   do_check_eq(result.artifacts.hash, undefined);
   do_check_eq(result.artifacts.mac, "S3f8E4hAURAqJxOlsYugkPZxLoRYrClgbSQ/3FmKMbY=");
 
+  // Empty payload changes nothing.
+  result = compute(makeURI("http://example.net/path"), method,
+                   { credentials: credentials_sha256,
+                     ts: 1353809207,
+                     nonce: "Ygvqdz",
+                     payload: null,
+                   });
+  do_check_eq(result.artifacts.hash, undefined);
+  do_check_eq(result.artifacts.mac, "S3f8E4hAURAqJxOlsYugkPZxLoRYrClgbSQ/3FmKMbY=");
+
   result = compute(makeURI("http://example.net/path"), method,
                    { credentials: credentials_sha256,
                      ts: 1353809207,