csharp-sdk/samples/ProtectedMcpClient/Program.cs

using Microsoft.Extensions.Logging;
using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol;
using System.Diagnostics;
using System.Net;
using System.Text;
using System.Web;

var serverUrl = "http://localhost:7071/";

Console.WriteLine("Protected MCP Client");
Console.WriteLine($"Connecting to weather server at {serverUrl}...");
Console.WriteLine();

// We can customize a shared HttpClient with a custom handler if desired
var sharedHandler = new SocketsHttpHandler
{
    PooledConnectionLifetime = TimeSpan.FromMinutes(2),
    PooledConnectionIdleTimeout = TimeSpan.FromMinutes(1)
};
var httpClient = new HttpClient(sharedHandler);

var consoleLoggerFactory = LoggerFactory.Create(builder =>
{
    builder.AddConsole();
});

var transport = new HttpClientTransport(new()
{
    Endpoint = new Uri(serverUrl),
    Name = "Secure Weather Client",
    OAuth = new()
    {
        RedirectUri = new Uri("http://localhost:1179/callback"),
        AuthorizationRedirectDelegate = HandleAuthorizationUrlAsync,
        DynamicClientRegistration = new()
        {
            ClientName = "ProtectedMcpClient",
        },
    }
}, httpClient, consoleLoggerFactory);

var client = await McpClient.CreateAsync(transport, loggerFactory: consoleLoggerFactory);

var tools = await client.ListToolsAsync();
if (tools.Count == 0)
{
    Console.WriteLine("No tools available on the server.");
    return;
}

Console.WriteLine($"Found {tools.Count} tools on the server.");
Console.WriteLine();

if (tools.Any(t => t.Name == "get_alerts"))
{
    Console.WriteLine("Calling get_alerts tool...");

    var result = await client.CallToolAsync(
        "get_alerts",
        new Dictionary<string, object?> { { "state", "WA" } }
    );

    Console.WriteLine("Result: " + ((TextContentBlock)result.Content[0]).Text);
    Console.WriteLine();
}

/// Handles the OAuth authorization URL by starting a local HTTP server and opening a browser.
/// This implementation demonstrates how SDK consumers can provide their own authorization flow.
/// </summary>
/// <param name="authorizationUrl">The authorization URL to open in the browser.</param>
/// <param name="redirectUri">The redirect URI where the authorization code will be sent.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>The authorization code extracted from the callback, or null if the operation failed.</returns>
static async Task<string?> HandleAuthorizationUrlAsync(Uri authorizationUrl, Uri redirectUri, CancellationToken cancellationToken)
{
    Console.WriteLine("Starting OAuth authorization flow...");
    Console.WriteLine($"Opening browser to: {authorizationUrl}");

    var listenerPrefix = redirectUri.GetLeftPart(UriPartial.Authority);
    if (!listenerPrefix.EndsWith("/")) listenerPrefix += "/";

    using var listener = new HttpListener();
    listener.Prefixes.Add(listenerPrefix);

    try
    {
        listener.Start();
        Console.WriteLine($"Listening for OAuth callback on: {listenerPrefix}");

        OpenBrowser(authorizationUrl);

        var context = await listener.GetContextAsync();
        var query = HttpUtility.ParseQueryString(context.Request.Url?.Query ?? string.Empty);
        var code = query["code"];
        var error = query["error"];

        string responseHtml = "<html><body><h1>Authentication complete</h1><p>You can close this window now.</p></body></html>";
        byte[] buffer = Encoding.UTF8.GetBytes(responseHtml);
        context.Response.ContentLength64 = buffer.Length;
        context.Response.ContentType = "text/html";
        context.Response.OutputStream.Write(buffer, 0, buffer.Length);
        context.Response.Close();

        if (!string.IsNullOrEmpty(error))
        {
            Console.WriteLine($"Auth error: {error}");
            return null;
        }

        if (string.IsNullOrEmpty(code))
        {
            Console.WriteLine("No authorization code received");
            return null;
        }

        Console.WriteLine("Authorization code received successfully.");
        return code;
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error getting auth code: {ex.Message}");
        return null;
    }
    finally
    {
        if (listener.IsListening) listener.Stop();
    }
}

/// <summary>
/// Opens the specified URL in the default browser.
/// </summary>
/// <param name="url">The URL to open.</param>
static void OpenBrowser(Uri url)
{
    // Validate the URI scheme - only allow safe protocols
    if (url.Scheme != Uri.UriSchemeHttp && url.Scheme != Uri.UriSchemeHttps)
    {
        Console.WriteLine($"Error: Only HTTP and HTTPS URLs are allowed.");
        return;
    }

    try
    {
        var psi = new ProcessStartInfo
        {
            FileName = url.ToString(),
            UseShellExecute = true
        };
        Process.Start(psi);
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error opening browser: {ex.Message}");
        Console.WriteLine($"Please manually open this URL: {url}");
    }
}