如何用 C# 在 WebView2 中识别 reCAPTCHA（WinForms、WPF）

dotnet new winforms -n WvApp
cd WvApp
dotnet add package Microsoft.Web.WebView2
dotnet add package CapSkip

async Task StartAsync()
{
    var dataDir = Path.Combine(
        Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "WvApp");
    var env = await CoreWebView2Environment.CreateAsync(null, dataDir);
    await webView.EnsureCoreWebView2Async(env);
    webView.CoreWebView2.NavigationCompleted += OnNavigationCompleted;
    webView.CoreWebView2.Navigate(LoginUrl);
}

// data-sitekey first, then the anchor iframe that an explicit render leaves
// behind (api2 for reCAPTCHA, enterprise for reCAPTCHA Enterprise)
const string FindSitekeyJs = """
    (() => {
      const el = document.querySelector('.g-recaptcha[data-sitekey]');
      if (el) return el.getAttribute('data-sitekey');
      const f = document.querySelector('iframe[src*="/recaptcha/"][src*="/anchor?"]');
      return f ? new URL(f.src).searchParams.get('k') : null;
    })()
    """;

async Task<string?> EvalStringAsync(string js) =>
    JsonSerializer.Deserialize<string>(await webView.CoreWebView2.ExecuteScriptAsync(js));

// In OnNavigationCompleted, where core is webView.CoreWebView2.
// Throws: ConfigureAwait(false) resumes on a thread-pool thread
var result = await solver.RecaptchaAsync(sitekey, core.Source).ConfigureAwait(false);
await webView.CoreWebView2.ExecuteScriptAsync("document.title");
// System.InvalidOperationException: CoreWebView2 can only be accessed from the UI thread.

// Works: a plain await inside a WinForms event handler comes back on the UI
// thread
var result = await solver.RecaptchaAsync(sitekey, core.Source);
await webView.CoreWebView2.ExecuteScriptAsync("document.title");

// fill every response textarea, then call data-callback or submit the form
const string InjectJs = """
    (token => {
      const boxes = document.querySelectorAll('textarea[name="g-recaptcha-response"]');
      boxes.forEach(b => { b.value = token; });
      const cb = document.querySelector('.g-recaptcha[data-callback]')?.dataset.callback;
      if (cb && typeof window[cb] === 'function') { window[cb](token); return 'called ' + cb; }
      const form = boxes[0]?.form;
      if (!form) return 'no form found';
      if (!form.checkValidity()) return 'form has empty required fields';
      form.requestSubmit();
      return 'submitted the form';
    })
    """;

// Form1.cs, in a project made with: dotnet new winforms -n WvApp
using System.Text.Json;
using CapSkip;
using Microsoft.Web.WebView2.Core;
using Microsoft.Web.WebView2.WinForms;

namespace WvApp;

public partial class Form1 : Form
{
    const string LoginUrl = "https://example.com/login";

    // data-sitekey first, then the anchor iframe that an explicit render leaves
    // behind (api2 for reCAPTCHA, enterprise for reCAPTCHA Enterprise)
    const string FindSitekeyJs = """
        (() => {
          const el = document.querySelector('.g-recaptcha[data-sitekey]');
          if (el) return el.getAttribute('data-sitekey');
          const f = document.querySelector('iframe[src*="/recaptcha/"][src*="/anchor?"]');
          return f ? new URL(f.src).searchParams.get('k') : null;
        })()
        """;

    const string IsInvisibleJs = """
        (() => {
          const f = document.querySelector('iframe[src*="/recaptcha/"][src*="/anchor?"]');
          if (f) return new URL(f.src).searchParams.get('size') === 'invisible';
          const el = document.querySelector('.g-recaptcha[data-sitekey]');
          if (!el) return false;
          if (el.getAttribute('data-size') === 'invisible') return true;
          return el.tagName === 'BUTTON' && !el.hasAttribute('data-action');
        })()
        """;

    // fill every response textarea, then call data-callback or submit the form
    const string InjectJs = """
        (token => {
          const boxes = document.querySelectorAll('textarea[name="g-recaptcha-response"]');
          boxes.forEach(b => { b.value = token; });
          const cb = document.querySelector('.g-recaptcha[data-callback]')?.dataset.callback;
          if (cb && typeof window[cb] === 'function') { window[cb](token); return 'called ' + cb; }
          const form = boxes[0]?.form;
          if (!form) return 'no form found';
          if (!form.checkValidity()) return 'form has empty required fields';
          form.requestSubmit();
          return 'submitted the form';
        })
        """;

    readonly WebView2 webView = new() { Dock = DockStyle.Fill };
    readonly CapSkipClient solver = new(host: "127.0.0.1", port: 8080);
    readonly CancellationTokenSource cts = new();

    public Form1()
    {
        InitializeComponent();
        Controls.Add(webView);
        Load += async (_, _) => await StartAsync();
        FormClosing += (_, _) => cts.Cancel();
    }

    async Task StartAsync()
    {
        var dataDir = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "WvApp");
        var env = await CoreWebView2Environment.CreateAsync(null, dataDir);
        await webView.EnsureCoreWebView2Async(env);
        webView.CoreWebView2.NavigationCompleted += OnNavigationCompleted;
        webView.CoreWebView2.Navigate(LoginUrl);
    }

    async Task<string?> EvalStringAsync(string js) =>
        JsonSerializer.Deserialize<string>(await webView.CoreWebView2.ExecuteScriptAsync(js));

    async void OnNavigationCompleted(object? sender, CoreWebView2NavigationCompletedEventArgs e)
    {
        var core = webView.CoreWebView2;
        var sitekey = await EvalStringAsync(FindSitekeyJs);
        if (sitekey is null) return;                      // no widget on this page
        core.NavigationCompleted -= OnNavigationCompleted; // solve once, not on the result page
        var invisible = await core.ExecuteScriptAsync(IsInvisibleJs) == "true";
        var options = invisible ? new Dictionary<string, object?> { ["invisible"] = 1 } : null;
        Text = "Solving reCAPTCHA...";
        try
        {
            var result = await solver.RecaptchaAsync(sitekey, core.Source, options, cts.Token);
            var token = JsonSerializer.Serialize(result.Code);
            Text = "reCAPTCHA solved, " + await EvalStringAsync($"({InjectJs})({token})");
        }
        catch (Exception) when (cts.IsCancellationRequested) { } // window closed mid-solve
        catch (CapSkipError ex) { Text = "CapSkip error: " + ex.Message; }
    }
}

// a field: the page's iframes, filled before Navigate() and pruned as they go
readonly List<CoreWebView2Frame> frames = new();

// in StartAsync, before Navigate():
webView.CoreWebView2.FrameCreated += (_, e) =>
{
    var frame = e.Frame; // read it once: each read returns a new wrapper
    frames.Add(frame);
    frame.Destroyed += (_, _) => frames.Remove(frame);
};

// widget inside a cross-origin iframe: run the same scripts in that frame
async Task SolveInFramesAsync()
{
    foreach (var frame in frames.ToList())
    {
        var key = JsonSerializer.Deserialize<string>(await frame.ExecuteScriptAsync(FindSitekeyJs));
        if (key is null) continue;
        var href = JsonSerializer.Deserialize<string>(await frame.ExecuteScriptAsync("location.href"))!;
        var result = await solver.RecaptchaAsync(key, href, null, cts.Token);
        var token = JsonSerializer.Serialize(result.Code);
        await frame.ExecuteScriptAsync($"({InjectJs})({token})");
        return;
    }
}

// for pages that add the widget after the load event
async Task<string?> WaitForSitekeyAsync(TimeSpan timeout)
{
    var deadline = DateTime.UtcNow + timeout;
    while (DateTime.UtcNow < deadline)
    {
        var key = await EvalStringAsync(FindSitekeyJs);
        if (key is not null) return key;
        await Task.Delay(250);
    }
    return null;
}

// CapSkip in Server mode on another Windows machine on your network
var solver = new CapSkipClient(apiKey: "YOUR_API_KEY", host: "192.168.1.50", port: 8080);

try
{
    var result = await solver.RecaptchaAsync(sitekey, core.Source, options, cts.Token);
    var token = JsonSerializer.Serialize(result.Code);
    Text = "reCAPTCHA solved, " + await EvalStringAsync($"({InjectJs})({token})");
}
catch (Exception) when (cts.IsCancellationRequested) { } // window closed mid-solve
catch (NetworkException ex) { Text = "Is CapSkip running? " + ex.Message; }
catch (ApiException ex) { Text = "CapSkip could not solve it: " + ex.Message; }
catch (CapSkip.TimeoutException) { Text = "No answer before the timeout"; }
catch (CapSkipError ex) { Text = "CapSkip error: " + ex.Message; }