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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "storage/common/quota/padding_key.h"
#include <inttypes.h>
#include <cstdint>
#include "base/numerics/byte_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/time/time.h"
#include "crypto/hash.h"
#include "crypto/hmac.h"
#include "crypto/random.h"
#include "net/base/schemeful_site.h"
#include "net/http/http_request_headers.h"
#include "services/network/public/mojom/url_response_head.mojom-shared.h"
#include "third_party/blink/public/common/storage_key/storage_key.h"
namespace storage {
namespace {
// The range of the padding added to response sizes for opaque resources.
// Increment the CacheStorage padding version if changed.
constexpr uint64_t kPaddingRange = 14431 * 1024;
} // namespace
bool ShouldPadResponseType(network::mojom::FetchResponseType type) {
return type == network::mojom::FetchResponseType::kOpaque ||
type == network::mojom::FetchResponseType::kOpaqueRedirect;
}
int64_t ComputeRandomResponsePadding() {
uint64_t raw_random = 0;
crypto::RandBytes(base::byte_span_from_ref(raw_random));
return raw_random % kPaddingRange;
}
int64_t ComputeStableResponsePadding(const blink::StorageKey& storage_key,
const std::string& response_url,
const base::Time& response_time,
const std::string& request_method,
int64_t side_data_size) {
static std::array<uint8_t, 16> s_padding_key;
static bool s_padding_key_generated = false;
if (!s_padding_key_generated) {
// This just needs to be consistent within a single browser session, so we
// generate it the first time we need it.
crypto::RandBytes(s_padding_key);
s_padding_key_generated = true;
}
DCHECK(!response_url.empty());
net::SchemefulSite site(storage_key.origin());
DCHECK_GT(response_time, base::Time::UnixEpoch());
int64_t microseconds =
(response_time - base::Time::UnixEpoch()).InMicroseconds();
// It should only be possible to have a CORS safe-listed method here since
// the spec does not permit other methods for no-cors requests.
DCHECK(request_method == net::HttpRequestHeaders::kGetMethod ||
request_method == net::HttpRequestHeaders::kHeadMethod ||
request_method == net::HttpRequestHeaders::kPostMethod);
std::string key = base::StringPrintf(
"%s-%" PRId64 "-%s-%s-%" PRId64, response_url.c_str(), microseconds,
site.Serialize().c_str(), request_method.c_str(), side_data_size);
auto hmac = crypto::hmac::SignSha256(s_padding_key, base::as_byte_span(key));
return base::U64FromNativeEndian(base::as_byte_span(hmac).first<8>()) %
kPaddingRange;
}
} // namespace storage
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