CefResourceRequestHandler

Header: cef_resource_request_handler.h
Interfaces: CefResourceRequestHandler, CefCookieAccessFilter
Category: Browser Handlers

Overview

User-implemented handler interfaces returned from CefClient and registered with CefBrowserHost.

CefResourceRequestHandler

Source File: include/cef_resource_request_handler.h

Process / Thread Context: Browser process / IO thread (default for all methods). USER-IMPLEMENTED (source=client); returned from CefRequestHandler::GetResourceRequestHandler (and from CefRequestContextHandler::GetResourceRequestHandler).

Purpose: Per-request handler for resource interception. Distinguished from CefResourceHandler (file 3) as follows: CefResourceRequestHandler is invoked by CEF on every request to perform pre-load interception (cookie filtering, redirect control, response filtering, completion notifications, OS protocol execution); CefResourceHandler is the custom stream reader returned by CefResourceRequestHandler::GetResourceHandler when the application wants to fully synthesize the response itself.

Methods

`CefRefPtr<CefCookieAccessFilter> GetCookieAccessFilter(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request)`

Parameters:

request: Request contents; cannot be modified.

Return Value: Return a CefCookieAccessFilter to filter cookies; NULL to use default cookie handling.

Usage Instruction: Provides per-request cookie gating.

Threading Constraint: "Called on the IO thread before a resource request is loaded."

`ReturnValue OnBeforeResourceLoad(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefCallback> callback)`

Parameters:

request: The request; may be modified (URL change = redirect).
callback: Used when returning RV_CONTINUE_ASYNC.

Return Value: RV_CONTINUE = proceed immediately; RV_CONTINUE_ASYNC = call callback->Continue()/Cancel() later; RV_CANCEL = cancel immediately.

Usage Instruction: Mutate headers/URL before the request goes on the wire, or block it.

Threading Constraint: "Called on the IO thread before a resource request is loaded."

`CefRefPtr<CefResourceHandler> GetResourceHandler(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request)`

Parameters:

request: Cannot be modified.

Return Value: NULL = use default network loader; otherwise return a CefResourceHandler to fully synthesize the response.

Usage Instruction: Use to implement custom schemes or in-app data: URLs.

Threading Constraint: "Called on the IO thread before a resource is loaded."

`void OnResourceRedirect(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefResponse> response, CefString& new_url)`

Parameters:

request: Contains the old URL and request info; read-only.
response: The response that caused the redirect; read-only.

Return Value: None.

Usage Instruction: Rewrite or block redirects by changing new_url.

Threading Constraint: "Called on the IO thread when a resource load is redirected."

`bool OnResourceResponse(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefResponse> response)`

Parameters:

browser, frame, request, response (read-only).

Return Value: false = proceed without modification. true = redirect/retry by modifying request (URL change = redirect).

Usage Instruction: Deprecated for redirects — header explicitly warns: "Use OnBeforeResourceLoad or GetResourceHandler to perform redirects." Requests handled with the default network loader cannot be redirected here.

Threading Constraint: "Called on the IO thread when a resource response is received."

`CefRefPtr<CefResponseFilter> GetResourceResponseFilter(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefResponse> response)`

Parameters:

browser, frame, request, response (all read-only).

Return Value: NULL = no filtering; otherwise return a CefResponseFilter to transform response body bytes.

Usage Instruction: Use to rewrite response bytes on the fly (e.g. compress, sanitize HTML).

Threading Constraint: "Called on the IO thread to optionally filter resource response content."

`void OnResourceLoadComplete(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefResponse> response, URLRequestStatus status, int64_t received_content_length)`

Parameters:

status: cef_urlrequest_status_t completion status.
received_content_length: Number of bytes actually read.

Return Value: None.

Usage Instruction: Called for all requests (including aborted ones at shutdown). The header explicitly warns: may arrive after CefLifeSpanHandler::OnBeforeClose; use CefFrame::IsValid and do not call state-modifying methods if the frame is invalid.

Threading Constraint: "Called on the IO thread when a resource load has completed."

`void OnProtocolExecution(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, bool& allow_os_execution)`

Parameters:

request: Read-only.

Return Value: None.

Usage Instruction: Header explicitly warns of SECURITY risk: enforce scheme/host/URL restrictions before enabling OS execution.

Threading Constraint: "Called on the IO thread to handle requests for URLs with an unknown protocol component."

Usage Example

cpp

class MyResourceRequestHandler : public CefResourceRequestHandler {
 public:
  ReturnValue OnBeforeResourceLoad(CefRefPtr<CefBrowser> b,
                                   CefRefPtr<CefFrame> f,
                                   CefRefPtr<CefRequest> req,
                                   CefRefPtr<CefCallback> cb) override {
    CefRequest::HeaderMap hdrs;
    req->GetHeaderMap(hdrs);
    hdrs.insert({"X-Custom-Header", "value"});
    req->SetHeaderMap(hdrs);
    return RV_CONTINUE;
  }

  CefRefPtr<CefResourceHandler> GetResourceHandler(
      CefRefPtr<CefBrowser>, CefRefPtr<CefFrame>, CefRefPtr<CefRequest> req) override {
    if (req->GetURL().ToString() == "app://home")
      return new MyCustomResourceHandler();  // from file 3
    return nullptr;
  }

  CefRefPtr<CefResponseFilter> GetResourceResponseFilter(
      CefRefPtr<CefBrowser>, CefRefPtr<CefFrame>,
      CefRefPtr<CefRequest>, CefRefPtr<CefResponse>) override {
    return new MyResponseFilter();  // from file 4
  }
  // ... GetCookieAccessFilter, OnResourceRedirect, OnResourceResponse,
  // OnResourceLoadComplete, OnProtocolExecution
  IMPLEMENT_REFCOUNTING(MyResourceRequestHandler);
};

// Plugged in via:
//   CefRefPtr<CefResourceRequestHandler>
//   MyRequestHandler::GetResourceRequestHandler(...) { return new MyResourceRequestHandler; }

CefCookieAccessFilter

Source File: include/cef_resource_request_handler.h

Process / Thread Context: Browser process / IO thread. USER-IMPLEMENTED (source=client); returned from CefResourceRequestHandler::GetCookieAccessFilter.

Purpose: Filter individual cookies that may be sent with a request or saved from a response.

Methods

`bool CanSendCookie(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, const CefCookie& cookie)`

Parameters:

request: Read-only.
cookie: The cookie under consideration.

Return Value: true to send the cookie with the request; false to omit it.

Usage Instruction: Implement per-cookie gating on the send side.

Threading Constraint: "Called on the IO thread before a resource request is sent."

`bool CanSaveCookie(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, CefRefPtr<CefRequest> request, CefRefPtr<CefResponse> response, const CefCookie& cookie)`

Parameters:

cookie: The cookie the response wants to store.

Return Value: true to save; false to drop.

Usage Instruction: Implement per-cookie gating on the receive side.

Threading Constraint: "Called on the IO thread after a resource response is received."

Usage Example

cpp

class MyCookieFilter : public CefCookieAccessFilter {
 public:
  bool CanSendCookie(CefRefPtr<CefBrowser>, CefRefPtr<CefFrame>,
                    CefRefPtr<CefRequest>, const CefCookie& c) override {
    // Block third-party tracking cookies
    return std::string(c.domain.str).find("tracker.example") == std::string::npos;
  }
  bool CanSaveCookie(CefRefPtr<CefBrowser>, CefRefPtr<CefFrame>,
                     CefRefPtr<CefRequest>, CefRefPtr<CefResponse>,
                     const CefCookie& c) override { return true; }
  IMPLEMENT_REFCOUNTING(MyCookieFilter);
};

// Returned from MyResourceRequestHandler::GetCookieAccessFilter(...)

CefResourceRequestHandler ​

Overview ​