.NET Core 3 Web Api Cors fetch 一直 307 Temporary Redirect

.NET Core 3 Web Api Cors fetch 一直 307 Temporary Redirect

继上一篇 .net core 3 web api jwt 一直 401 为添加JWT-BearerToken认证所述的坑后，
本次为添加CORS跨域，又踩坑了。

自从 .NET Core 2.2 之后，CORS跨域配置代码发生了很大变化。
在 .NET Core 3.1 中，本作者碰到各种HTTP错误，诸如 500、307、401 等错误代码...
在必应Bing和不断Debug调整配置代码位置后，得知：

1. AllowAnyOrigin 方法，在新的 CORS 中间件已经被阻止使用允许任意 Origin，所以该方法无效。
2. AllowCredentials 方法，自从 .NET Core 2.2 之后，不允许和AllowAnyOrigin同时调用。
3. WithOrigins 方法，在 .NET Core 3.1 中有bug，具体原因未知，暂时只能用SetIsOriginAllowed(t=> true)代替，等效.AllowAnyOrigin方法。
4. 创建项目默认的模板中，app.UseHttpsRedirection()在前面，所以我将app.UseCors()放在它后面，这是导致HTTP 307 Temporary Redirect福报的根本原因之一。
5. 度娘告诉我，app.UseCors()方法要在app.UseAuthentication()之后，是误人子弟的，其实放在它前面也可以，并且app.UseCors()要在app.UseRouting()之后，app.UseEndpoints()和app.UseHttpsRedirection()之前
6. 使用fetch跨域请求时，要注意controller的action是否有设置除了HttpOptions之外的其它Http Method方法，如果有要加上HttpOptions标记特性，因为fetch跨域请求会先执行OPTIONS预请求。
7. 使用fetch请求需要JWT认证的接口时，除了在HTTP Headers设置Authorization之外，还需要设置'credentials': 'include'。
8. 写app.UseXxxxxx方法，引入中间件时，要注意管道(Middleware)注册顺序。

参考：

• CORS配置：https://docs.microsoft.com/zh-cn/aspnet/core/security/cors?view=aspnetcore-3.1
• JWT认证：https://docs.microsoft.com/zh-cn/aspnet/core/security/authentication/?view=aspnetcore-3.1
• Cors Issue: https://github.com/dotnet/aspnetcore/issues/16672
• Forum: https://forums.asp.net/t/2160821.aspx?CORS+in+ASP+NET+Core+3+x

源代码

以下是在 .NET Core 3.1下经过严谨测试，可以JWT认证、CORS跨域、IIS托管、自寄主运行的源代码，仅供参考。

WebApi.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <RootNamespace>WebApi</RootNamespace>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="3.1.2" />
    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="3.1.2" />
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="3.1.2" />
    <PackageReference Include="Microsoft.Extensions.Logging.EventSource" Version="3.1.2" />
    <PackageReference Include="Microsoft.Extensions.Logging.TraceSource" Version="3.1.2" />
    <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="3.1.2" />
    <PackageReference Include="Microsoft.TeamFoundationServer.Client" Version="16.153.0" />
    <PackageReference Include="Microsoft.VisualStudio.Services.Client" Version="16.153.0" />
    <PackageReference Include="Microsoft.VisualStudio.Services.InteractiveClient" Version="16.153.0" />
    <PackageReference Include="NLog.Web.AspNetCore" Version="4.9.0" />
  </ItemGroup>
</Project>

Program.cs

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using NLog.Extensions.Logging;
using System.Diagnostics;
using System.IO;

namespace WebApi
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args)
        {
            return Host.CreateDefaultBuilder(args)
                .ConfigureLogging((context, logging) =>
                {
                    logging.ClearProviders()
#if DEBUG
                        .AddConsole()
                        .AddDebug()
                        .AddEventLog()
                        .AddTraceSource(new SourceSwitch(nameof(Program), "Warning"), new ConsoleTraceListener())
#endif
                        .AddNLog();
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseContentRoot(Directory.GetCurrentDirectory())
                       .UseKestrel()
                       .UseIISIntegration()
                       .UseIIS()
                       .UseStartup<Startup>();
                });
        }
    }
}

Startup.cs

using MCS.Vsts.Options;
using MCS.Vsts.Services;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpOverrides;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.IdentityModel.Tokens;
using System.Text;

namespace WebApi
{
    public class Startup
    {
        public IConfiguration Configuration { get; }

        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            //认证
            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearer(options =>
                {
                    var secretBytes = Encoding.UTF8.GetBytes(Configuration["ServerConfig:Secret"]);
                    options.TokenValidationParameters = new TokenValidationParameters()
                    {
                        IssuerSigningKey = new SymmetricSecurityKey(secretBytes),
                        ValidateIssuer = false,
                        ValidateAudience = false,
                        ValidateActor = false,
                        RequireSignedTokens = true,
                        RequireExpirationTime = true,
                        ValidateLifetime = true
                    };
                });

            //跨域
            services.AddCors(options =>
            {
                options.AddDefaultPolicy(builder =>
                {
                    builder
                    //允许任何来源的主机访问
                    //TODO: 新的 CORS 中间件已经阻止允许任意 Origin，即设置 AllowAnyOrigin 也不会生效
                    //AllowAnyOrigin()
                    //设置允许访问的域
                    //TODO: 目前.NET Core 3.1 有 bug, 暂时通过 SetIsOriginAllowed 解决
                    //.WithOrigins(Configuration["CorsConfig:Origin"])
                    .SetIsOriginAllowed(t=> true)
                    .AllowAnyMethod()
                    .AllowAnyHeader()
                    .AllowCredentials();
                });
            });

            //TODO: do something...
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                //Enabled HSTS
                app.UseHsts();
            }

            //TODO: 要放在UseCors之后
            //app.UseHttpsRedirection();

            app.UseRouting();

            app.UseForwardedHeaders(new ForwardedHeadersOptions
            {
                ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
            });

            //TODO: UseCors要在UseRouting之后，UseEndpoints 和 UseHttpsRedirection 之前
            app.UseCors();

            app.UseAuthentication();

            app.UseAuthorization();

            app.UseHttpsRedirection();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "https_port": 44370,
  "urls": "http://*:50867",
  "ServerConfig": {
    "Secret": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
  },
  "CorsConfig": {
    "BaseUri": "http://myserver"
  }
}