用c#嵌套CefSharp浏览器拦截修改post提交的数据

首先，需要在CefSharp浏览器中注册一个自定义的请求处理程序，可以继承CefSharp.IRequestHandler接口，并实现其中的方法来拦截和修改请求数据。

下面是一个示例代码，可以在提交POST请求时，修改请求数据：

using CefSharp;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;

namespace CefSharpDemo
{
    public class CustomRequestHandler : IRequestHandler
    {
        public bool OnBeforeBrowse(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, bool isRedirect)
        {
            return false;
        }

        public bool OnBeforeResourceLoad(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
        {
            return false;
        }

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

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

        public bool OnRenderProcessTerminated(IWebBrowser chromiumWebBrowser, IBrowser browser, CefTerminationStatus status)
        {
            return false;
        }

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

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

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

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

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

        public void OnProtocolExecution(IWebBrowser chromiumWebBrowser, IBrowser browser, string url)
        {
        }

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

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

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

        public void OnResourceLoadComplete(IWebBrowser chromiumWebBrowser, IBrowser browser, IFrame frame, IRequest request, IResponse response, UrlRequestStatus status, long receivedContentLength)
        {
            // 判断请求类型是否为POST
            if (request.Method == "POST")
            {
                // 读取请求数据
                using (var postData = request.PostData)
                {
                    if (postData != null)
                    {
                        var elements = postData.Elements;

                        // 修改请求数据
                        foreach (var element in elements)
                        {
                            if (element.Type == PostDataElementType.Bytes)
                            {
                                var body = element.GetBytes();
                                var bodyString = Encoding.UTF8.GetString(body);
                                var newBodyString = bodyString.Replace("old", "new");
                                var newBody = Encoding.UTF8.GetBytes(newBodyString);
                                element.SetToBytes(newBody.Length, newBody);
                            }
                        }
                    }
                }
            }
        }
    }
}

然后，在创建CefSharp浏览器时，需要将自定义的请求处理程序注册到浏览器中：

var browserSettings = new BrowserSettings();
browserSettings.WebSecurity = CefState.Disabled;

var requestHandler = new CustomRequestHandler();
var browser = new ChromiumWebBrowser("https://www.baidu.com", browserSettings, requestHandler);

在这个示例中，当浏览器发起POST请求时，会将请求数据中包含的所有“old”字符串替换为“new”，然后再继续提交请求。可以根据实际需求修改这个逻辑。

注意：CefSharp浏览器的注册和使用需要引用相应的NuGet包，具体可以参考CefSharp官方文档。