如何在 C# 中用 HCaptchaAsync 识别 hCaptcha（.NET 8+）

dotnet new console -o hcaptcha-demo
cd hcaptcha-demo
dotnet add package CapSkip

using System.Net;
using System.Text.RegularExpressions;
using CapSkip;
using SolverTimeout = CapSkip.TimeoutException;  // System.TimeoutException is in scope too (CS0104)

static class Solve
{
    // Local mode. In Server mode, use your server's address instead. If API Key
    // Validation is on in CapSkip, also pass apiKey: "YOUR_KEY" here.
    static readonly CapSkipClient Client = new(host: "127.0.0.1", port: 8080);

    public static Task<SolveResult> Run(string siteKey, string pageUrl, bool invisible,
                                        string? rqData, Uri? proxy, CancellationToken ct)
    {
        var options = new Dictionary<string, object?>();
        if (rqData is not null) options["data"] = rqData;  // Enterprise rqdata, fresh per task
        if (proxy is not null)
        {
            // Uri.Authority drops a default port such as 80, so build host:port by hand.
            var login = proxy.UserInfo.Length > 0 ? Uri.UnescapeDataString(proxy.UserInfo) + "@" : "";
            options["proxy"] = new Proxy(proxy.Scheme.ToUpperInvariant(), $"{login}{proxy.Host}:{proxy.Port}");
        }
        // invisible: false sends nothing, true sends invisible=1.
        return Client.HCaptchaAsync(siteKey, pageUrl, invisible, options, ct);
    }
}

static class Site
{
    // One HttpClient per sign-up, because the cookie jar belongs to the handler and two
    // sign-ups must not share cookies. Dispose it when the sign-up is over.
    public static async Task<(HttpStatusCode Status, string Body)> SignUp(
        string pageUrl, SolveResult solved, string email, Uri? proxy, CancellationToken ct)
    {
        var handler = new HttpClientHandler { CookieContainer = new CookieContainer() };
        if (proxy is not null)
        {
            var address = new UriBuilder(proxy.Scheme, proxy.Host, proxy.Port).Uri;
            var login = proxy.UserInfo.Split(':', 2).Select(Uri.UnescapeDataString).ToArray();
            handler.Proxy = new WebProxy(address)
            {
                Credentials = login.Length == 2 ? new NetworkCredential(login[0], login[1]) : null,
            };
        }
        using var http = new HttpClient(handler) { Timeout = TimeSpan.FromSeconds(30) };
        // The User-Agent the token was earned with, on the page load and on the post.
        if (solved.UserAgent is not null)
            http.DefaultRequestHeaders.TryAddWithoutValidation("User-Agent", solved.UserAgent);

        using (await http.GetAsync(pageUrl, ct)) { }  // the page's own cookies land in the jar

        var origin = new Uri(pageUrl).GetLeftPart(UriPartial.Authority);
        using var post = new HttpRequestMessage(HttpMethod.Post, pageUrl)
        {
            Content = new FormUrlEncodedContent(new Dictionary<string, string>
            {
                ["email"] = email,  // your form's own fields go here
                ["h-captcha-response"] = solved.Token!,  // always set on an hCaptcha result
                ["g-recaptcha-response"] = solved.Token!,  // the widget fills both
            }),
        };
        post.Headers.TryAddWithoutValidation("Referer", pageUrl);  // HttpClient sends none
        post.Headers.TryAddWithoutValidation("Origin", origin);
        using var response = await http.SendAsync(post, ct);
        return (response.StatusCode, await response.Content.ReadAsStringAsync(ct));
    }
}

static class Program
{
    const string PageUrl = "https://example.com/signup";  // the page that shows the widget
    const string SiteKey = "YOUR_SITEKEY";  // the data-sitekey of its h-captcha div
    static readonly Uri? ProxyUri = null;  // for example new Uri("http://user:[email protected]:8080")

    // The reply body is the exception message, JSON on a poll and bare text on a submit.
    static string ErrorCode(ApiException ex)
    {
        var found = Regex.Match(ex.Message, "ERROR_[A-Z_]+");
        return found.Success ? found.Value : ex.Message;
    }

    static async Task<int> Main()
    {
        // One budget for every attempt. Cancelling it stops a wait or a request at once.
        using var budget = new CancellationTokenSource(TimeSpan.FromMinutes(6));
        try
        {
            for (var attempt = 1; attempt <= 3; attempt++)
            {
                SolveResult solved;
                try
                {
                    solved = await Solve.Run(SiteKey, PageUrl, invisible: false, rqData: null, ProxyUri, budget.Token);
                }
                catch (ApiException ex) when (ErrorCode(ex) is "ERROR_CAPTCHA_UNSOLVABLE" or "ERROR_NO_SLOT_AVAILABLE")
                {
                    Console.WriteLine($"attempt {attempt}: {ErrorCode(ex)}, new task");
                    // The second code means the key is over its rate limit, so pause first.
                    if (ErrorCode(ex) == "ERROR_NO_SLOT_AVAILABLE") await Task.Delay(TimeSpan.FromSeconds(5), budget.Token);
                    continue;
                }

                var (status, body) = await Site.SignUp(PageUrl, solved, "[email protected]", ProxyUri, budget.Token);
                if ((int)status < 400)
                {
                    Console.WriteLine($"{(int)status} {body[..Math.Min(40, body.Length)]}");
                    return 0;
                }
                Console.WriteLine($"attempt {attempt}: the site answered {(int)status}, new token");
            }
            Console.WriteLine("no accepted form after 3 attempts");
        }
        // A cancelled submit surfaces as a NetworkException, a cancelled poll as a
        // TaskCanceledException, so test the budget itself.
        catch (Exception) when (budget.IsCancellationRequested) { Console.WriteLine("the 6 minute budget ran out"); }
        catch (ApiException ex) { Console.WriteLine($"CapSkip answered {ErrorCode(ex)}"); }
        catch (SolverTimeout ex) { Console.WriteLine($"no token in time: {ex.Message}"); }
        catch (CapSkipError ex) { Console.WriteLine($"{ex.GetType().Name}: {ex.Message}"); }
        catch (HttpRequestException ex) { Console.WriteLine($"request failed: {ex.Message}"); }
        catch (TaskCanceledException) { Console.WriteLine("the site did not answer in 30 seconds"); }  // HttpClient.Timeout
        return 1;
    }
}

// Snippet, not part of Program.cs. In Main, replace the Solve.Run line with one of these.
// An invisible widget (data-size="invisible"):
solved = await Solve.Run(SiteKey, PageUrl, invisible: true, rqData: null, ProxyUri, budget.Token);
// An Enterprise widget. Read a fresh rqdata value from the page before every attempt,
// because it is single use. The literal below stands in for that code.
solved = await Solve.Run(SiteKey, PageUrl, invisible: false, rqData: "RQDATA_FROM_THE_PAGE", ProxyUri, budget.Token);

// Snippet, not part of Program.cs. In Main, replace the lines between the braces of the outer try
// with these, and keep the catch lines. Three accounts sign up at once on one SDK client.
var emails = new[] { "[email protected]", "[email protected]", "[email protected]" };
var codes = await Task.WhenAll(emails.Select(async email =>
{
    var solved = await Solve.Run(SiteKey, PageUrl, false, null, ProxyUri, budget.Token);
    var (status, _) = await Site.SignUp(PageUrl, solved, email, ProxyUri, budget.Token);
    return (int)status;
}));
Console.WriteLine(string.Join(" ", codes));
return codes.All(c => c < 400) ? 0 : 1;