chromium - send custom header info on initial page load c#

Question

Or How to inject a custom header into the initial request to a site when new-ing up an instance of the ChromiumWebBrowser.

I\'m a noob with Chromium

Answer 1

You should create a class that implement IRequestHandler then set an instance of that class as RequestHandler in your browser object.

With version 53, that class should look like:

class ChromeBrowserRequestHandler: IRequestHandler
    {
        public bool GetAuthCredentials(IWebBrowser browserControl, IBrowser browser, IFrame frame, bool isProxy, string host, int port, string realm, string scheme, IAuthCallback callback)
        {
            return false;
        }

        public bool OnBeforeBrowse(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, bool isRedirect)
        {
            return false;
        }

        public bool OnBeforePluginLoad(IWebBrowser browser, string url, string policyUrl, WebPluginInfo info)
        {
            return false;
        }

        public CefReturnValue OnBeforeResourceLoad(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
        {
            var headers = request.Headers;
            headers["Custom-Header"] = "My Custom Header";
            request.Headers = headers;

            return CefReturnValue.Continue;
        }

        public bool OnCertificateError(IWebBrowser browser, CefErrorCode errorCode, string requestUrl)
        {
            return false;
        }

        public void OnPluginCrashed(IWebBrowser browser, string pluginPath)
        {
        }

        public void OnRenderProcessTerminated(IWebBrowser browserControl, IBrowser browser, CefTerminationStatus status)
        {
        }

        public IResponseFilter GetResourceResponseFilter(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response) 
        { 
            return null; 
        }

        public bool OnCertificateError(IWebBrowser browserControl, IBrowser browser, CefErrorCode errorCode, string requestUrl, ISslInfo sslInfo, IRequestCallback callback) 
        {
            return false; 
        }

        public bool OnOpenUrlFromTab(IWebBrowser browserControl, IBrowser browser, IFrame frame, string targetUrl, WindowOpenDisposition targetDisposition, bool userGesture) 
        {
            return false; 
        }

        public void OnPluginCrashed(IWebBrowser browserControl, IBrowser browser, string pluginPath) 
        {
        }

        public bool OnProtocolExecution(IWebBrowser browserControl, IBrowser browser, string url) 
        {
            return false;
        }

        public bool OnQuotaRequest(IWebBrowser browserControl, IBrowser browser, string originUrl, long newSize, IRequestCallback callback) 
        {
            return false;
        }

        public void OnRenderViewReady(IWebBrowser browserControl, IBrowser browser) 
        { 
        }

        public void OnResourceLoadComplete(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response, UrlRequestStatus status, long receivedContentLength)
        { 
        }

        public void OnResourceRedirect(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, ref string newUrl) 
        { 
        }

        public bool OnResourceResponse(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response) 
        {
            return false;
        }
    }

Then, while creating your browser object:

ChromiumWebBrowser myBrowser = new ChromiumWebBrowser("whatever.com")
{
    RequestHandler = new ChromeBrowserRequestHandler()
};

Note that the request handler must be set before loading the page. If you can't set the request handler during instanctiaction, you can still set it later a reload the page with myBrowser.Load("whatever.com") .

Answer 2

Updated to reflect major Chromium changes

Updated to reflect changes made in version 75 (should work in 75 and newer)

The method you're after should be OnBeforeResourceLoad, a basic example should look like:

public class CustomResourceRequestHandler : ResourceRequestHandler
{
    protected override CefReturnValue OnBeforeResourceLoad(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
    {
        var headers = request.Headers;
        headers["User-Agent"] = "My User Agent";
        request.Headers = headers;

        return CefReturnValue.Continue;
    }
}

public class CustomRequestHandler : RequestHandler
{
    protected override IResourceRequestHandler GetResourceRequestHandler(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, bool isNavigation, bool isDownload, string requestInitiator, ref bool disableDefaultHandling)
    {
        return new CustomResourceRequestHandler();
    }
}

browser.RequestHandler = new CustomRequestHandler();

Using the IRequest.Headers property you must read the headers property, make changes then reassign it. It's now possible to use the SetHeaderByName/GetHeaderByName functions to get/set a single header.

• RequestHandler API Doc
• ResourceRequestHandler API Doc
• IRequest.GetHeaderByName API Doc
• IRequest.SetHeaderByName API Doc

Answer 3

In the one of the latest versions some callbacks have been moved from IRequestHandler to IResourceRequestHandler interface. Simplest way is to override default implementations RequestHandler & ResourceRequestHandler, for example:

class BearerAuthResourceRequestHandler : ResourceRequestHandler
    {
        public BearerAuthResourceRequestHandler(string token)
        {
            _token = token;
        }

        private string _token;

        protected override CefReturnValue OnBeforeResourceLoad(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
        {
            if (!string.IsNullOrEmpty(_token))
            {
                var headers = request.Headers;
                headers["Authorization"] = $"Bearer {_token}";
                request.Headers = headers;
                return CefReturnValue.Continue;
            }
            else return base.OnBeforeResourceLoad(chromiumWebBrowser, browser, frame, request, callback);
        }

    }
    class BearerAuthRequestHandler : RequestHandler
    {
        public BearerAuthRequestHandler(string token)
        {
            _token = token;
        }

        private string _token;

        protected override IResourceRequestHandler GetResourceRequestHandler(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, bool isNavigation, bool isDownload, string requestInitiator, ref bool disableDefaultHandling)
        {
            if (!string.IsNullOrEmpty(_token)) return new BearerAuthResourceRequestHandler(_token);
            else return base.GetResourceRequestHandler(chromiumWebBrowser, browser, frame, request, isNavigation, isDownload, requestInitiator, ref disableDefaultHandling);
        }
    }

Then, assign it to browser RequestHandler:

Browser.RequestHandler = new BearerAuthRequestHandler(token);