blob: d5a9c889ca5446391087bc7784b6eb2e3f1f0121 [file] [log] [blame]
// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "extensions/browser/extension_function_dispatcher.h"
#include <utility>
#include "base/debug/crash_logging.h"
#include "base/functional/bind.h"
#include "base/json/json_string_value_serializer.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/process/process.h"
#include "base/ranges/algorithm.h"
#include "base/scoped_observation.h"
#include "base/trace_event/typed_macros.h"
#include "base/tracing/protos/chrome_track_event.pbzero.h"
#include "base/values.h"
#include "build/build_config.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/render_process_host_observer.h"
#include "content/public/browser/service_worker_context.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/common/result_codes.h"
#include "content/public/common/url_constants.h"
#include "extensions/browser/api_activity_monitor.h"
#include "extensions/browser/bad_message.h"
#include "extensions/browser/extension_function_registry.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/browser/extension_system.h"
#include "extensions/browser/extension_util.h"
#include "extensions/browser/extensions_browser_client.h"
#include "extensions/browser/process_manager.h"
#include "extensions/browser/process_map.h"
#include "extensions/browser/quota_service.h"
#include "extensions/browser/script_injection_tracker.h"
#include "extensions/browser/service_worker/service_worker_keepalive.h"
#include "extensions/common/constants.h"
#include "extensions/common/context_type_adapter.h"
#include "extensions/common/extension_api.h"
#include "extensions/common/extension_messages.h"
#include "extensions/common/extension_set.h"
#include "extensions/common/extension_urls.h"
#include "extensions/common/trace_util.h"
#include "ipc/ipc_message.h"
#include "ipc/ipc_message_macros.h"
#include "mojo/public/cpp/bindings/message.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
using content::BrowserThread;
using perfetto::protos::pbzero::ChromeTrackEvent;
namespace extensions {
namespace {
// Notifies the ApiActivityMonitor that an extension API function has been
// called. May be called from any thread.
void NotifyApiFunctionCalled(const ExtensionId& extension_id,
const std::string& api_name,
const base::Value::List& args,
content::BrowserContext* browser_context) {
activity_monitor::OnApiFunctionCalled(browser_context, extension_id, api_name,
args);
}
bool IsRequestFromServiceWorker(const mojom::RequestParams& request_params) {
return request_params.service_worker_version_id !=
blink::mojom::kInvalidServiceWorkerVersionId;
}
// Calls ResponseCallback with an empty result.
void ResponseCallbackOnError(ExtensionFunction::ResponseCallback callback,
ExtensionFunction::ResponseType type,
const std::string& error) {
std::move(callback).Run(type, base::Value::List(), error, nullptr);
}
// Returns `true` if `render_process_host` can legitimately claim to send IPC
// messages on behalf of `extension_id`. `render_frame_host` parameter is
// needed to account for scenarios involving a Chrome Web Store frame.
bool CanRendererActOnBehalfOfExtension(
const ExtensionId& extension_id,
content::RenderFrameHost* render_frame_host,
content::RenderProcessHost& render_process_host) {
// TODO(lukasza): Some of the checks below can be restricted to specific
// context types (e.g. an empty `extension_id` should not happen in an
// extension context; and the SiteInstance-based check should only be needed
// for hosted apps). Consider leveraging ProcessMap::GetMostLikelyContextType
// to implement this kind of restrictions. Note that
// ExtensionFunctionDispatcher::CreateExtensionFunction already calls
// GetMostLikelyContextType - some refactoring might be needed to avoid
// duplicating the work.
// Allow empty extension id (it seems okay to assume that no
// extension-specific special powers will be granted without an extension id).
// For instance, WebUI pages may call private APIs like developerPrivate,
// settingsPrivate, metricsPrivate, and others. In these cases, there is no
// associated extension ID.
//
// TODO(lukasza): Investigate if the exception below can be avoided if
// `render_process_host` hosts HTTP origins (i.e. if the exception can be
// restricted to NTP, and/or chrome://... cases.
if (extension_id.empty())
return true;
// Did `render_process_id` run a content script or user script from
// `extension_id`?
// TODO(https://crbug.com/1186557): Ideally, we'd only check content script/
// user script status if the renderer claimed to be acting on behalf of the
// corresponding type (e.g. Feature::CONTENT_SCRIPT_CONTEXT). We evaluate this
// later in ProcessMap::CanProcessHostContextType(), but we could be stricter
// by including it here.
if (ScriptInjectionTracker::DidProcessRunContentScriptFromExtension(
render_process_host, extension_id) ||
ScriptInjectionTracker::DidProcessRunUserScriptFromExtension(
render_process_host, extension_id)) {
return true;
}
// Can `render_process_id` host a chrome-extension:// origin (frame, worker,
// etc.)?
if (util::CanRendererHostExtensionOrigin(render_process_host.GetID(),
extension_id)) {
return true;
}
if (render_frame_host) {
DCHECK_EQ(render_process_host.GetID(),
render_frame_host->GetProcess()->GetID());
content::SiteInstance& site_instance =
*render_frame_host->GetSiteInstance();
// Chrome Extension APIs can be accessed from some hosted apps.
//
// Today this is mostly needed by the Chrome Web Store's hosted app, but the
// code below doesn't make this assumption and allows *all* hosted apps
// based on the trustworthy, Browser-side information from the SiteInstance
// / SiteURL. This way the code is resilient to future changes + there are
// concerns that `chrome.test.sendMessage` might already be exposed to
// hosted apps (but maybe not covered by tests).
//
// Note that the condition below allows all extensions (i.e. not just hosted
// apps), but hosted apps aren't covered by the
// `CanRendererHostExtensionOrigin` call above (because the process lock of
// hosted apps is based on a https://, rather than chrome-extension:// url).
//
// GuestView is explicitly excluded, because we don't want to allow
// GuestViews to spoof the extension id of their host.
if (!site_instance.IsGuest() &&
extension_id == util::GetExtensionIdForSiteInstance(site_instance)) {
return true;
}
}
// Disallow any other cases.
return false;
}
absl::optional<bad_message::BadMessageReason> ValidateRequest(
const mojom::RequestParams& params,
content::RenderFrameHost* render_frame_host,
content::RenderProcessHost& render_process_host) {
if ((render_frame_host && IsRequestFromServiceWorker(params)) ||
(!render_frame_host && !IsRequestFromServiceWorker(params))) {
return bad_message::EFD_BAD_MESSAGE;
}
if (!CanRendererActOnBehalfOfExtension(params.extension_id, render_frame_host,
render_process_host)) {
return bad_message::EFD_INVALID_EXTENSION_ID_FOR_PROCESS;
}
// TODO(https://crbug.com/1186447): Validate `params.user_gesture`.
return absl::nullopt;
}
const char* ToString(bad_message::BadMessageReason bad_message_code) {
switch (bad_message_code) {
case bad_message::BadMessageReason::EFD_BAD_MESSAGE:
return "LocalFrameHost::Request got a bad message.";
case bad_message::BadMessageReason::EFD_INVALID_EXTENSION_ID_FOR_PROCESS:
return "LocalFrameHost::Request: renderer never hosted such extension";
default:
NOTREACHED();
return "LocalFrameHost::Request encountered unrecognized validation "
"error.";
}
}
// Helper for logging crash keys related to a the IPC payload from
// mojom::RequestParams.
class ScopedRequestParamsCrashKeys {
public:
explicit ScopedRequestParamsCrashKeys(const mojom::RequestParams& params)
: name_(GetNameCrashKey(), params.name),
extension_id_(GetExtensionIdCrashKey(), params.extension_id) {}
~ScopedRequestParamsCrashKeys() = default;
// No copy constructor and no copy assignment operator.
ScopedRequestParamsCrashKeys(const ScopedRequestParamsCrashKeys&) = delete;
ScopedRequestParamsCrashKeys& operator=(const ScopedRequestParamsCrashKeys&) =
delete;
private:
static base::debug::CrashKeyString* GetNameCrashKey() {
static auto* crash_key = base::debug::AllocateCrashKeyString(
"RequestParams-name", base::debug::CrashKeySize::Size256);
return crash_key;
}
static base::debug::CrashKeyString* GetExtensionIdCrashKey() {
static auto* crash_key = base::debug::AllocateCrashKeyString(
"RequestParams-extension_id", base::debug::CrashKeySize::Size64);
return crash_key;
}
base::debug::ScopedCrashKeyString name_;
base::debug::ScopedCrashKeyString extension_id_;
};
} // namespace
WindowController*
ExtensionFunctionDispatcher::Delegate::GetExtensionWindowController() const {
return nullptr;
}
content::WebContents*
ExtensionFunctionDispatcher::Delegate::GetAssociatedWebContents() const {
return nullptr;
}
content::WebContents*
ExtensionFunctionDispatcher::Delegate::GetVisibleWebContents() const {
return GetAssociatedWebContents();
}
ExtensionFunctionDispatcher::ExtensionFunctionDispatcher(
content::BrowserContext* browser_context)
: browser_context_(browser_context), delegate_(nullptr) {}
ExtensionFunctionDispatcher::~ExtensionFunctionDispatcher() {
}
void ExtensionFunctionDispatcher::Dispatch(
mojom::RequestParamsPtr params,
content::RenderFrameHost& frame,
mojom::LocalFrameHost::RequestCallback callback) {
content::RenderProcessHost& process = *frame.GetProcess();
TRACE_EVENT("extensions", "ExtensionFunctionDispatcher::Dispatch",
ChromeTrackEvent::kRenderProcessHost, process,
ChromeTrackEvent::kChromeExtensionId,
ExtensionIdForTracing(params->extension_id));
ScopedRequestParamsCrashKeys request_params_crash_keys(*params);
SCOPED_CRASH_KEY_STRING256(
"extensions", "frame.GetSiteInstance()",
frame.GetSiteInstance()->GetSiteURL().possibly_invalid_spec());
if (auto bad_message_code = ValidateRequest(*params, &frame, process)) {
// Kill the renderer if it's an invalid request.
bad_message::ReceivedBadMessage(&process, *bad_message_code);
std::move(callback).Run(ExtensionFunction::FAILED, base::Value::List(),
ToString(*bad_message_code), nullptr);
return;
}
// TODO(https://crbug.com/1227812): Validate (or remove) `params.source_url`.
DispatchWithCallbackInternal(
*params, &frame, *frame.GetProcess(),
base::BindOnce(
[](mojom::LocalFrameHost::RequestCallback callback,
ExtensionFunction::ResponseType type, base::Value::List results,
const std::string& error,
mojom::ExtraResponseDataPtr response_data) {
std::move(callback).Run(type == ExtensionFunction::SUCCEEDED,
std::move(results), error,
std::move(response_data));
},
std::move(callback)));
}
void ExtensionFunctionDispatcher::DispatchForServiceWorker(
mojom::RequestParamsPtr params,
int render_process_id,
mojom::ServiceWorkerHost::RequestWorkerCallback callback) {
ScopedRequestParamsCrashKeys request_params_crash_keys(*params);
// The IPC might race with RenderProcessHost destruction. This may only
// happen in scenarios that are already inherently racey, so dropping the IPC
// is okay and won't lead to any additional risk of data loss. Continuing is
// impossible, because WorkerResponseCallbackWrapper requires render process
// host to be around.
content::RenderProcessHost* rph =
content::RenderProcessHost::FromID(render_process_id);
if (!rph) {
std::move(callback).Run(ExtensionFunction::FAILED, base::Value::List(),
"No RPH", nullptr);
return;
}
TRACE_EVENT("extensions",
"ExtensionFunctionDispatcher::DispatchForServiceWorker",
ChromeTrackEvent::kRenderProcessHost, *rph,
ChromeTrackEvent::kChromeExtensionId,
ExtensionIdForTracing(params->extension_id));
if (auto bad_message_code = ValidateRequest(*params, nullptr, *rph)) {
// Kill the renderer if it's an invalid request.
bad_message::ReceivedBadMessage(render_process_id, *bad_message_code);
std::move(callback).Run(ExtensionFunction::FAILED, base::Value::List(),
ToString(*bad_message_code), nullptr);
return;
}
WorkerId worker_id{params->extension_id, render_process_id,
params->service_worker_version_id,
params->worker_thread_id};
// Ignore if the worker has already stopped.
if (!ProcessManager::Get(browser_context_)->HasServiceWorker(worker_id)) {
std::move(callback).Run(ExtensionFunction::FAILED, base::Value::List(),
"No SW", nullptr);
return;
}
DispatchWithCallbackInternal(
*params, nullptr, *rph,
base::BindOnce(
[](mojom::ServiceWorkerHost::RequestWorkerCallback callback,
ExtensionFunction::ResponseType type, base::Value::List results,
const std::string& error,
mojom::ExtraResponseDataPtr response_data) {
std::move(callback).Run(type == ExtensionFunction::SUCCEEDED,
std::move(results), error,
std::move(response_data));
},
std::move(callback)));
}
void ExtensionFunctionDispatcher::DispatchWithCallbackInternal(
const mojom::RequestParams& params,
content::RenderFrameHost* render_frame_host,
content::RenderProcessHost& render_process_host,
ExtensionFunction::ResponseCallback callback) {
ProcessMap* process_map = ProcessMap::Get(browser_context_);
if (!process_map) {
constexpr char kProcessNotFound[] =
"The process for the extension is not found.";
ResponseCallbackOnError(std::move(callback), ExtensionFunction::FAILED,
kProcessNotFound);
return;
}
const int render_process_id = render_process_host.GetID();
const GURL* render_frame_host_url = nullptr;
if (render_frame_host) {
render_frame_host_url = &render_frame_host->GetLastCommittedURL();
DCHECK_EQ(render_process_id, render_frame_host->GetProcess()->GetID());
}
ExtensionRegistry* registry = ExtensionRegistry::Get(browser_context_);
const Extension* extension =
registry->enabled_extensions().GetByID(params.extension_id);
// Check if the call is from a hosted app. Hosted apps can only make call from
// render frames, so we can use `render_frame_host_url`.
// TODO(devlin): Isn't `params.extension_id` still populated for hosted app
// calls?
if (!extension && render_frame_host_url) {
extension = registry->enabled_extensions().GetHostedAppByURL(
*render_frame_host_url);
}
Feature::Context context_type =
MojomContextToFeatureContext(params.context_type);
if (!process_map->CanProcessHostContextType(extension, render_process_host,
context_type)) {
// TODO(https://crbug.com/1186557): Ideally, we'd be able to mark some
// of these as bad messages. We can't do that in all cases because there
// are times some of these might legitimately fail (for instance, during
// extension unload), but there are others that should never, ever happen
// (privileged extension contexts in web processes).
static constexpr char kInvalidContextType[] =
"Invalid context type provided.";
ResponseCallbackOnError(std::move(callback), ExtensionFunction::FAILED,
kInvalidContextType);
return;
}
if (context_type == Feature::WEBUI_UNTRUSTED_CONTEXT) {
// TODO(https://crbug.com/1435575): We should, at minimum, be using an
// origin here. It'd be even better if we could have a more robust way of
// checking that a process can host untrusted webui.
if (extension || !render_frame_host_url ||
!render_frame_host_url->SchemeIs(content::kChromeUIUntrustedScheme)) {
constexpr char kInvalidWebUiUntrustedContext[] =
"Context indicated it was untrusted webui, but is invalid.";
ResponseCallbackOnError(std::move(callback), ExtensionFunction::FAILED,
kInvalidWebUiUntrustedContext);
return;
}
}
const bool is_worker_request = IsRequestFromServiceWorker(params);
scoped_refptr<ExtensionFunction> function = CreateExtensionFunction(
params, extension, render_process_id, is_worker_request,
render_frame_host_url, context_type, ExtensionAPI::GetSharedInstance(),
std::move(callback), render_frame_host);
if (!function.get())
return;
if (extension &&
ExtensionsBrowserClient::Get()->CanExtensionCrossIncognito(
extension, browser_context_)) {
function->set_include_incognito_information(true);
}
if (!extension) {
if (function->source_context_type() == Feature::WEBUI_CONTEXT) {
base::UmaHistogramSparse("Extensions.Functions.WebUICalls",
function->histogram_value());
} else if (function->source_context_type() ==
Feature::WEBUI_UNTRUSTED_CONTEXT) {
base::UmaHistogramSparse("Extensions.Functions.WebUIUntrustedCalls",
function->histogram_value());
} else if (function->source_context_type() == Feature::WEB_PAGE_CONTEXT) {
base::UmaHistogramSparse("Extensions.Functions.NonExtensionWebPageCalls",
function->histogram_value());
}
// Skip the quota, event page, activity logging stuff if there
// isn't an extension, e.g. if the function call was from WebUI.
function->RunWithValidation().Execute();
return;
}
// Fetch the ProcessManager before |this| is possibly invalidated.
ProcessManager* process_manager = ProcessManager::Get(browser_context_);
ExtensionSystem* extension_system = ExtensionSystem::Get(browser_context_);
QuotaService* quota = extension_system->quota_service();
std::string violation_error =
quota->Assess(extension->id(), function.get(), params.arguments,
base::TimeTicks::Now());
if (violation_error.empty()) {
// See crbug.com/39178.
ExtensionsBrowserClient::Get()->PermitExternalProtocolHandler();
NotifyApiFunctionCalled(extension->id(), params.name, params.arguments,
browser_context_);
// Note: Deliberately don't include external component extensions here -
// this lets us differentiate between "built-in" extension calls and
// external extension calls
if (extension->location() == mojom::ManifestLocation::kComponent) {
base::UmaHistogramSparse("Extensions.Functions.ComponentExtensionCalls",
function->histogram_value());
} else {
base::UmaHistogramSparse("Extensions.Functions.ExtensionCalls",
function->histogram_value());
}
if (IsRequestFromServiceWorker(params)) {
base::UmaHistogramSparse(
"Extensions.Functions.ExtensionServiceWorkerCalls",
function->histogram_value());
}
if (extension->manifest_version() == 3) {
base::UmaHistogramSparse("Extensions.Functions.ExtensionMV3Calls",
function->histogram_value());
}
base::ElapsedTimer timer;
function->RunWithValidation().Execute();
// TODO(devlin): Once we have a baseline metric for how long functions take,
// we can create a handful of buckets and record the function name so that
// we can find what the fastest/slowest are.
// Note: Many functions execute finish asynchronously, so this time is not
// always a representation of total time taken. See also
// Extensions.Functions.TotalExecutionTime.
UMA_HISTOGRAM_TIMES("Extensions.Functions.SynchronousExecutionTime",
timer.Elapsed());
} else {
function->OnQuotaExceeded(violation_error);
}
// Note: do not access |this| after this point. We may have been deleted
// if function->Run() ended up closing the tab that owns us.
// Check if extension was uninstalled by management.uninstall.
if (!registry->enabled_extensions().GetByID(params.extension_id))
return;
function->set_request_uuid(base::Uuid::GenerateRandomV4());
// Increment the keepalive to ensure the extension doesn't shut down while
// it's executing an API function.
if (IsRequestFromServiceWorker(params)) {
CHECK(function->worker_id());
content::ServiceWorkerExternalRequestTimeoutType timeout_type =
function->ShouldKeepWorkerAliveIndefinitely()
? content::ServiceWorkerExternalRequestTimeoutType::kDoesNotTimeout
: content::ServiceWorkerExternalRequestTimeoutType::kDefault;
function->set_service_worker_keepalive(
std::make_unique<ServiceWorkerKeepalive>(
browser_context_, *function->worker_id(), timeout_type,
Activity::API_FUNCTION, function->name()));
} else {
process_manager->IncrementLazyKeepaliveCount(
function->extension(), Activity::API_FUNCTION, function->name());
}
}
void ExtensionFunctionDispatcher::OnExtensionFunctionCompleted(
ExtensionFunction& extension_function) {
if (!extension_function.extension()) {
// The function had no associated extension; nothing to clean up.
return;
}
if (!extension_function.browser_context()) {
// The ExtensionFunction's browser context is null'ed out when the browser
// context is being shut down. If this happens, there's nothing to clean up.
return;
}
if (!ExtensionRegistry::Get(browser_context_)
->enabled_extensions()
.GetByID(extension_function.extension()->id())) {
// The extension may have been unloaded (the ExtensionFunction holds a
// reference to it, so it's still safe to access). If so, there's nothing to
// // clean up.
return;
}
ProcessManager* process_manager = ProcessManager::Get(browser_context_);
if (extension_function.is_from_service_worker()) {
CHECK(extension_function.request_uuid().is_valid());
CHECK(extension_function.worker_id());
extension_function.ResetServiceWorkerKeepalive();
} else {
process_manager->DecrementLazyKeepaliveCount(extension_function.extension(),
Activity::API_FUNCTION,
extension_function.name());
}
}
WindowController*
ExtensionFunctionDispatcher::GetExtensionWindowController() const {
return delegate_ ? delegate_->GetExtensionWindowController() : nullptr;
}
content::WebContents*
ExtensionFunctionDispatcher::GetAssociatedWebContents() const {
return delegate_ ? delegate_->GetAssociatedWebContents() : nullptr;
}
content::WebContents*
ExtensionFunctionDispatcher::GetVisibleWebContents() const {
return delegate_ ? delegate_->GetVisibleWebContents() :
GetAssociatedWebContents();
}
void ExtensionFunctionDispatcher::AddResponseTarget(ExtensionFunction* func) {
response_targets_.insert(func);
}
void ExtensionFunctionDispatcher::ProcessResponseAck(
const base::Uuid& request_uuid) {
auto iter = base::ranges::find_if(
response_targets_, [request_uuid](ExtensionFunction* function) {
return function->request_uuid() == request_uuid;
});
if (iter == response_targets_.end()) {
return;
}
// Calling this may cause the instance to delete itself, so no
// referencing it after this!
(*iter)->OnResponseAck();
response_targets_.erase(iter);
}
scoped_refptr<ExtensionFunction>
ExtensionFunctionDispatcher::CreateExtensionFunction(
const mojom::RequestParams& params,
const Extension* extension,
int requesting_process_id,
bool is_worker_request,
const GURL* render_frame_host_url,
Feature::Context context_type,
ExtensionAPI* api,
ExtensionFunction::ResponseCallback callback,
content::RenderFrameHost* render_frame_host) {
constexpr char kCreationFailed[] = "Access to extension API denied.";
scoped_refptr<ExtensionFunction> function =
ExtensionFunctionRegistry::GetInstance().NewFunction(params.name);
if (!function) {
LOG(ERROR) << "Unknown Extension API - " << params.name;
ResponseCallbackOnError(std::move(callback), ExtensionFunction::FAILED,
kCreationFailed);
return nullptr;
}
function->SetArgs(params.arguments.Clone());
// Determine the source URL. When possible, prefer fetching this value from
// the RenderFrameHost, but fallback to the value in the `params` object if
// necessary.
// We can't use the frame URL in the case of a worker-based request (where
// there is no frame).
if (is_worker_request) {
// TODO(https://crbug.com/1227812): Validate this URL further. Or, better,
// remove it from `mojom::RequestParams`.
function->set_source_url(params.source_url);
} else {
DCHECK(render_frame_host_url);
function->set_source_url(*render_frame_host_url);
}
function->set_has_callback(params.has_callback);
function->set_user_gesture(params.user_gesture);
function->set_extension(extension);
function->set_response_callback(std::move(callback));
function->set_source_context_type(context_type);
function->set_source_process_id(requesting_process_id);
if (is_worker_request) {
CHECK(extension);
WorkerId worker_id;
worker_id.thread_id = params.worker_thread_id;
worker_id.version_id = params.service_worker_version_id;
worker_id.render_process_id = requesting_process_id;
worker_id.extension_id = extension->id();
function->set_worker_id(std::move(worker_id));
} else {
function->SetRenderFrameHost(render_frame_host);
}
// Note: `SetDispatcher()` also initializes the `browser_context_` member
// for `ExtensionFunction`, which is necessary for properly performing
// permission checks.
function->SetDispatcher(weak_ptr_factory_.GetWeakPtr());
if (!function->HasPermission()) {
LOG(ERROR) << "Permission denied for " << params.name;
function->RespondWithError(kCreationFailed);
return nullptr;
}
return function;
}
} // namespace extensions