Bug 1420836 - Part1 - Provide a utility function to compute the storage id. r=cpearce

The CDM on Mac and Windows will ask the host for storage id.
We compute the storage id by hashing machine id, origin salt and browser id.

MozReview-Commit-ID: 4fTCaOKgSIe

--HG--
extra : rebase_source : 20fe8ab93966bb74b46eebbfbddc8486ceea4705

dom/media/gmp/CDMStorageIdProvider.cpp

@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CDMStorageIdProvider.h"
+#include "GMPLog.h"
+#include "nsCOMPtr.h"
+#include "nsComponentManagerUtils.h"
+#include "nsICryptoHash.h"
+
+#ifdef SUPPORT_STORAGE_ID
+#include "rlz/lib/machine_id.h"
+#endif
+
+namespace mozilla {
+
+/*static*/ nsCString
+CDMStorageIdProvider::ComputeStorageId(const nsCString& aOriginSalt)
+{
+#ifndef SUPPORT_STORAGE_ID
+  return EmptyCString();
+#else
+  GMP_LOG("CDMStorageIdProvider::ComputeStorageId");
+
+  std::string machineId;
+  if (!rlz_lib::GetMachineId(&machineId)) {
+    GMP_LOG("CDMStorageIdProvider::ComputeStorageId: get machineId failed.");
+    return EmptyCString();
+  }
+
+  std::string originSalt(aOriginSalt.BeginReading(), aOriginSalt.Length());
+  std::string input = machineId + originSalt + CDMStorageIdProvider::kBrowserIdentifier;
+  nsAutoCString storageId;
+  nsresult rv;
+  nsCOMPtr<nsICryptoHash> hasher = do_CreateInstance("@mozilla.org/security/hash;1", &rv);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    GMP_LOG("CDMStorageIdProvider::ComputeStorageId: no crypto hash(0x%08" PRIx32 ")",
+            static_cast<uint32_t>(rv));
+    return EmptyCString();
+  }
+
+  rv = hasher->Init(nsICryptoHash::SHA256);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    GMP_LOG("CDMStorageIdProvider::ComputeStorageId: failed to initialize hash(0x%08" PRIx32 ")",
+            static_cast<uint32_t>(rv));
+    return EmptyCString();
+  }
+
+  rv = hasher->Update(reinterpret_cast<const uint8_t*>(input.c_str()), input.size());
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    GMP_LOG("CDMStorageIdProvider::ComputeStorageId: failed to update hash(0x%08" PRIx32 ")",
+            static_cast<uint32_t>(rv));
+    return EmptyCString();
+  }
+
+  rv = hasher->Finish(false, storageId);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    GMP_LOG("CDMStorageIdProvider::ComputeStorageId: failed to get the final hash result(0x%08" PRIx32 ")",
+            static_cast<uint32_t>(rv));
+    return EmptyCString();
+  }
+  return storageId;
+#endif
+}
+
+} // namespace mozilla

dom/media/gmp/CDMStorageIdProvider.h

@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef CDMStorageIdProvider_h_
+#define CDMStorageIdProvider_h_
+
+/**
+ * CDM will try to request a latest version(0) of storage id.
+ * If the storage id computation algorithm changed, we should increase the kCurrentVersion.
+*/
+
+#include <string>
+
+#include "nsString.h"
+
+namespace mozilla {
+
+class CDMStorageIdProvider
+{
+  static constexpr const char* kBrowserIdentifier =
+    "mozilla_firefox_gecko";
+
+public:
+  // Should increase the value when the storage id algorithm changed.
+  static constexpr int kCurrentVersion = 1;
+  static constexpr int kCDMRequestLatestVersion = 0;
+
+  // Return empty string when
+  // 1. Call on unsupported storageid platform.
+  // 2. Failed to compute the storage id.
+  // This function only provide the storage id for kCurrentVersion=1.
+  // If you want to change the algorithm or output of storageid,
+  // you should keep the version 1 storage id and consider to provide
+  // higher version storage id in another function.
+  static nsCString ComputeStorageId(const nsCString& aOriginSalt);
+
+};
+
+} // namespace mozilla
+
+#endif // CDMStorageIdProvider_h_

dom/media/gmp/moz.build

@@ -66,6 +66,7 @@ EXPORTS += [
 ]
 
 UNIFIED_SOURCES += [
+    'CDMStorageIdProvider.cpp',
     'ChromiumCDMAdapter.cpp',
     'ChromiumCDMCallbackProxy.cpp',
     'ChromiumCDMChild.cpp',
@@ -120,6 +121,9 @@ IPDL_SOURCES += [
   'PGMPVideoEncoder.ipdl',
 ]
 
+if CONFIG['OS_TARGET'] in ['WINNT', 'Darwin']:
+    DEFINES['SUPPORT_STORAGE_ID'] = 1;
+
 # comment this out to use Unsafe Shmem for more performance
 DEFINES['GMP_SAFE_SHMEM'] = True