widevine-partner/android
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Creating a new RNG and replacing rand().

Browse Source 
[ Merge of http://go/wvgerrit/84607 ]
[ Merge of http://go/wvgerrit/84608 ]

The primary goal is to replace the use of `rand()` with the random
number generators provided with the C++11 standard.

This simplified generator wraps some of the technical aspects of the
<random> library and provides an interface for uniformly distributed
integers.

As part of the `rand()` purge in the CDM, all uses of the C random int
function in `core()` have been removed.  Places that previously used
`rand()` now use `CdmRandom` facilities.

Test: Linux unittest and Android unittest
Bug: 130680365
Change-Id: Ica383870536ed462dbb80e630c2d66845e38b937
This commit is contained in:
Alex Dale
2019-08-26 14:39:50 -07:00
parent 9da0617606
commit ee56d93454
12 changed files with 406 additions and 78 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
libwvdrmengine/cdm/core/src/cdm_engine.cpp
View File

@@ -12,6 +12,7 @@
#include <memory>
#include <sstream>
#include "cdm_random.h"
#include "cdm_session.h"
#include "cdm_session_map.h"
#include "clock.h"
@@ -69,8 +70,6 @@ class UsagePropertySet : public CdmClientPropertySet {
const std::string empty_;
};
bool CdmEngine::seeded_ = false;
CdmEngine::CdmEngine(FileSystem* file_system,
std::shared_ptr<metrics::EngineMetrics> metrics,
const std::string& spoid)
@@ -83,11 +82,7 @@ CdmEngine::CdmEngine(FileSystem* file_system,
usage_property_set_(),
last_usage_information_update_time_(0) {
assert(file_system);
if (!seeded_) {
Properties::Init();
srand(clock_.GetCurrentTime());
seeded_ = true;
}
Properties::Init();
}
CdmEngine::~CdmEngine() {
@@ -1260,7 +1255,8 @@ CdmResponseType CdmEngine::GetUsageInfo(const std::string& app_id,
CdmUsageInfo* usage_info) {
LOGI("Getting usage info: app_id = %s", app_id.c_str());
// Return a random usage report from a random security level
SecurityLevel security_level = ((rand() % 2) == 0) ? kLevelDefault : kLevel3;
SecurityLevel security_level =
CdmRandom::RandomBool() ? kLevelDefault : kLevel3;
CdmResponseType status = UNKNOWN_ERROR;
if (!usage_info) {
LOGE("No usage info destination");
@@ -1328,7 +1324,7 @@ CdmResponseType CdmEngine::GetUsageInfo(const std::string& app_id,
usage_info->resize(kUsageReportsPerRequest);
size_t index = rand() % usage_data.size();
size_t index = CdmRandom::RandomInRange(usage_data.size() - 1);
status = usage_session_->RestoreUsageSession(usage_data[index], error_detail);
if (KEY_ADDED != status) {
LOGE("RestoreUsageSession failed: index = %zu, status = %d", index,

40
libwvdrmengine/cdm/core/src/usage_table_header.cpp
View File

@@ -4,6 +4,7 @@
#include "usage_table_header.h"
#include "cdm_random.h"
#include "crypto_session.h"
#include "license.h"
#include "log.h"
@@ -21,6 +22,7 @@ std::string kOldUsageEntryServerMacKey(wvcdm::MAC_KEY_SIZE, 0);
std::string kOldUsageEntryClientMacKey(wvcdm::MAC_KEY_SIZE, 0);
std::string kOldUsageEntryPoviderSessionToken =
"nahZ6achSheiqua3TohQuei0ahwohv";
} // namespace
namespace wvcdm {
@@ -152,8 +154,11 @@ CdmResponseType UsageTableHeader::AddEntry(
for (uint32_t retry_count = 0; retry_count < kMaxCryptoRetries &&
status == INSUFFICIENT_CRYPTO_RESOURCES_3;
++retry_count) {
int64_t entry_number_to_delete = GetRandomInRange(usage_entry_info_.size());
if (entry_number_to_delete < 0) break;
if (usage_entry_info_.size() == 0) {
break;
}
uint32_t entry_number_to_delete =
CdmRandom::RandomInRange(usage_entry_info_.size() - 1);
DeleteEntry(entry_number_to_delete, file_handle_.get(), metrics);
status = crypto_session->CreateUsageEntry(usage_entry_number);
@@ -226,10 +231,14 @@ CdmResponseType UsageTableHeader::LoadEntry(CryptoSession* crypto_session,
for (uint32_t retry_count = 0; retry_count < kMaxCryptoRetries &&
status == INSUFFICIENT_CRYPTO_RESOURCES_3;
++retry_count) {
if (usage_entry_info_.size() <= 1) break;
// Get a random entry from the other entries.
int64_t entry_number_to_delete = GetRandomInRangeWithExclusion(
usage_entry_info_.size(), usage_entry_number);
if (entry_number_to_delete < 0) break;
uint32_t entry_number_to_delete =
CdmRandom::RandomInRange(usage_entry_info_.size() - 2);
if (entry_number_to_delete >= usage_entry_number) {
// Exclude |usage_entry_number|.
++entry_number_to_delete;
}
DeleteEntry(entry_number_to_delete, file_handle_.get(), metrics);
status = crypto_session->LoadUsageEntry(usage_entry_number, usage_entry);
}
@@ -723,27 +732,6 @@ bool UsageTableHeader::UpgradeUsageInfoFromUsageTable(
return NO_ERROR;
}
int64_t UsageTableHeader::GetRandomInRange(size_t upper_bound_exclusive) {
if (upper_bound_exclusive == 0) {
LOGE("|upper_bound_exclusive| must be > 0");
return -1;
}
return (int)((double)rand() / ((double)RAND_MAX + 1) * upper_bound_exclusive);
}
int64_t UsageTableHeader::GetRandomInRangeWithExclusion(
size_t upper_bound_exclusive, size_t exclude) {
if ((upper_bound_exclusive <= 1) || (exclude >= upper_bound_exclusive)) {
LOGE(
"|upper_bound_exclusive| must be > 1 and |exclude| must be < "
"|upper_bound_exclusive|");
return -1;
}
uint32_t random = GetRandomInRange(upper_bound_exclusive - 1);
if (random >= exclude) random++;
return random;
}
// TODO(fredgc): remove when b/65730828 is addressed
bool UsageTableHeader::CreateDummyOldUsageEntry(CryptoSession* crypto_session) {
return crypto_session->CreateOldUsageEntry(