.NET Core 8配置YARP反向代理（公网IP/端口）及iframe Cookie处理

1. 实现公网IP访问的反向代理并在iframe展示 #

步骤1：修正Program.cs的YARP配置与服务注册 #

确保应用监听公网IP，同时正确配置YARP的路由转发规则：

var builder = WebApplication.CreateBuilder(args);

// 注册YARP反向代理服务
builder.Services.AddReverseProxy()
    .LoadFromConfig(builder.Configuration.GetSection("ReverseProxy"));

// 注册控制器服务
builder.Services.AddControllersWithViews();

var app = builder.Build();

// 让应用监听公网IP（服务器部署时需确保对应端口防火墙已开放）
app.Urls.Add("http://0.0.0.0:你的公网端口");

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();

// 映射YARP代理端点
app.MapReverseProxy();

// 映射控制器默认路由
app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}");

app.Run();

在appsettings.json中配置YARP转发规则（替换https://target.example.com为你的目标URL）：

{
  "ReverseProxy": {
    "Routes": {
      "proxy-route": {
        "ClusterId": "target-cluster",
        "Match": {
          "Path": "/proxy/{**catch-all}"
        }
      }
    },
    "Clusters": {
      "target-cluster": {
        "Destinations": {
          "target-destination": {
            "Address": "https://target.example.com/"
          }
        }
      }
    }
  }
}

步骤2：修正HomeController的Proxy逻辑 #

无需手动使用HttpClientFactory，YARP已封装完整代理逻辑，你可以选择直接复用YARP路由，或通过IHttpForwarder自定义代理：

public class HomeController : Controller
{
    private readonly IHttpForwarder _httpForwarder;
    private readonly HttpMessageInvoker _httpClient;

    public HomeController(IHttpForwarder httpForwarder)
    {
        _httpForwarder = httpForwarder;
        // 初始化YARP需要的HttpMessageInvoker
        _httpClient = new HttpMessageInvoker(new SocketsHttpHandler
        {
            AllowAutoRedirect = false,
            UseProxy = false,
            EnableMultipleHttp2Connections = true,
            PooledConnectionLifetime = TimeSpan.FromMinutes(10)
        });
    }

    public IActionResult Index()
    {
        // 传递公网代理地址到视图
        ViewData["ProxyUrl"] = $"http://你的公网IP:你的公网端口/proxy";
        return View();
    }

    // 自定义代理Action（若需额外业务逻辑）
    public async Task Proxy()
    {
        // 拼接目标请求地址
        var targetPath = Request.Path.Value.Replace("/Home/Proxy", "");
        var targetUri = new Uri($"https://target.example.com{targetPath}");
        
        // 执行YARP转发
        var error = await _httpForwarder.SendAsync(HttpContext, targetUri.AbsoluteUri, _httpClient);
        if (error != ForwarderError.None)
        {
            // 处理代理错误逻辑
            var errorFeature = HttpContext.Features.Get<IForwarderErrorFeature>();
            var exception = errorFeature?.Exception;
        }
    }
}

步骤3：在Index视图中嵌入iframe #

直接在Index.cshtml中添加指向代理路由的iframe：

@{
    ViewData["Title"] = "Proxy Page";
}

<iframe src="@ViewData["ProxyUrl"]" width="100%" height="800px" frameborder="0"></iframe>

2. 解决Cookie/Session被设置到自身站点的问题 #

方法1：通过YARP转换修改Cookie属性 #

在Program.cs中添加Cookie转换逻辑，将目标站点的Cookie属性修正为对应域名：

builder.Services.AddReverseProxy()
    .LoadFromConfig(builder.Configuration.GetSection("ReverseProxy"))
    .AddTransforms<CookieTransformProvider>();

// 自定义Cookie转换类
public class CookieTransformProvider : ITransformProvider
{
    public void Apply(TransformBuilderContext context)
    {
        context.AddResponseTransform(async context =>
        {
            if (context.HttpContext.Response.Headers.TryGetValue(HeaderNames.SetCookie, out var cookies))
            {
                var modifiedCookies = new List<string>();
                foreach (var cookie in cookies)
                {
                    // 修改Cookie的Domain为目标站点域名，添加SameSite隔离属性
                    var modifiedCookie = cookie
                        .Replace("Domain=", "Domain=target.example.com; ")
                        + "; SameSite=None; Secure";
                    modifiedCookies.Add(modifiedCookie);
                }
                context.HttpContext.Response.Headers.SetCookie = modifiedCookies;
            }
        });
    }
}

方法2：使用iframe sandbox属性隔离Cookie #

在iframe标签中添加sandbox属性，让浏览器隔离iframe与主站的Cookie环境：

<iframe src="@ViewData["ProxyUrl"]" width="100%" height="800px" frameborder="0" sandbox="allow-same-origin allow-scripts allow-forms"></iframe>

注意：sandbox会限制iframe的部分权限，需根据业务需求调整允许的权限项。

内容的提问来源于stack exchange，提问作者user3404171