如何在不会挂掉的 .NET Worker Service 中识别验证码

dotnet new worker -n PortalWorker
cd PortalWorker
dotnet add package CapSkip
# Update Hosting before the next line: the template pins an older version,
# and the Windows Services package fails to restore against it (NU1605).
dotnet add package Microsoft.Extensions.Hosting
dotnet add package Microsoft.Extensions.Hosting.WindowsServices

// Program.cs
using CapSkip;
using PortalWorker;

var builder = Host.CreateApplicationBuilder(args);

// A Windows Service when the service manager starts it, an ordinary
// console app when you run it yourself.
builder.Services.AddWindowsService(options => options.ServiceName = "PortalWorker");

// One client for the whole process. The SDK reads no environment
// variables, but the host's configuration does, so CAPSKIP_HOST can come
// from the environment or from appsettings.json.
var config = builder.Configuration;
builder.Services.AddSingleton(new CapSkipClient(
    apiKey: config["CAPSKIP_API_KEY"] ?? "capskip",
    host: config["CAPSKIP_HOST"] ?? "127.0.0.1",
    port: int.Parse(config["CAPSKIP_PORT"] ?? "8080")));
builder.Services.AddSingleton<PortalLogin>();
builder.Services.AddHostedService<Worker>();

builder.Build().Run();

// PortalLogin.cs
using System.Net;
using System.Text.RegularExpressions;
using CapSkip;

namespace PortalWorker;

public sealed class PortalLogin(CapSkipClient solver, ILogger<PortalLogin> logger)
{
    const string PageUrl = "https://example.com/login";

    public async Task RunAsync(CancellationToken ct)
    {
        // A new HttpClient per run keeps its own cookies, so one run's
        // session never leaks into the next.
        using var http = new HttpClient();
        var html = await http.GetStringAsync(PageUrl, ct);
        var sitekey = Regex.Match(html, "data-sitekey=\"([^\"]+)\"").Groups[1].Value;

        // The form's hidden fields, such as a CSRF token.
        var fields = new Dictionary<string, string>();
        foreach (Match input in Regex.Matches(html, "<input[^>]*type=\"hidden\"[^>]*>"))
        {
            var name = Regex.Match(input.Value, "name=\"([^\"]+)\"").Groups[1].Value;
            var value = Regex.Match(input.Value, "value=\"([^\"]*)\"").Groups[1].Value;
            fields[name] = WebUtility.HtmlDecode(value);
        }

        // Pass the token on, so stopping the service cancels the solve.
        var result = await solver.RecaptchaAsync(sitekey, PageUrl, cancellationToken: ct);

        fields["username"] = "YOUR_USERNAME";
        fields["password"] = "YOUR_PASSWORD";
        fields["g-recaptcha-response"] = result.Code;
        using var post = new HttpRequestMessage(HttpMethod.Post, PageUrl)
        {
            Content = new FormUrlEncodedContent(fields),
        };
        // HttpClient sends no Referer; strict servers refuse a post without one.
        post.Headers.Referrer = new Uri(PageUrl);
        using var response = await http.SendAsync(post, ct);
        if (response.IsSuccessStatusCode)
            logger.LogInformation("Login posted: {Status}", (int)response.StatusCode);
        else
            logger.LogWarning("Login rejected: {Status}", (int)response.StatusCode);
    }
}

// Worker.cs
using CapSkip;

namespace PortalWorker;

public sealed class Worker(PortalLogin job, ILogger<Worker> logger) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        try
        {
            while (!stoppingToken.IsCancellationRequested)
            {
                var wait = TimeSpan.FromMinutes(15);
                try
                {
                    await job.RunAsync(stoppingToken);
                }
                catch (NetworkException ex) when (!stoppingToken.IsCancellationRequested)
                {
                    // CapSkip is not running yet, as after a reboot. Try again soon.
                    logger.LogWarning("CapSkip unreachable: {Message}", ex.Message);
                    wait = TimeSpan.FromSeconds(30);
                }
                catch (CapSkipError ex) when (!stoppingToken.IsCancellationRequested)
                {
                    logger.LogWarning("Solve failed: {Type}: {Message}", ex.GetType().Name, ex.Message);
                }
                catch (Exception ex) when ((ex is HttpRequestException or TaskCanceledException)
                                           && !stoppingToken.IsCancellationRequested)
                {
                    // The site failed, or HttpClient gave up on it after 100 s.
                    logger.LogWarning("The site did not answer: {Message}", ex.Message);
                }

                await Task.Delay(wait, stoppingToken);
            }
        }
        catch (Exception) when (stoppingToken.IsCancellationRequested)
        {
            // Stopping. A cancelled poll ends in TaskCanceledException and a
            // cancelled submit in NetworkException; neither is a failure.
        }
        catch (Exception ex)
        {
            logger.LogCritical(ex, "Worker failed");
            // Exit non-zero, so the service's recovery options restart it.
            // A host that stops on its own exits with code 0.
            Environment.Exit(1);
        }
    }
}

# In an elevated PowerShell. Paths are examples.
dotnet publish -c Release -r win-x64 -o C:\Services\PortalWorker
sc.exe create PortalWorker binpath= "C:\Services\PortalWorker\PortalWorker.exe" start= delayed-auto
sc.exe failure PortalWorker reset= 86400 actions= restart/60000/restart/60000/restart/60000
sc.exe start PortalWorker