从 ASP.NET Core 中的不同 HTTP 标头读取 JWT 令牌

在 ASP.NET Core API 项目中，我需要验证位于与 Authorization 标头不同的标头中的另一个 JWT Bearer 令牌。例如，假设发送 GET 请求以获取产品/api/products在名为的标头中带有不记名令牌AccessToken.

curl --location --request GET 'https://localhost/api/products' \
--header 'AccessToken: <bearer_token>'

我参考的是Microsoft.AspNetCore.Authentication.JwtBearer https://www.nuget.org/packages/Microsoft.AspNetCore.Authentication.JwtBearer/在 API 项目中打包并设置身份验证，如下所示：

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(JwtBearerDefaults.AuthenticationScheme, options => Configuration.Bind("JwtSettings", options));

但是，我在以下内容中找不到有关标头名称的任何内容JwtBearerOptions 类 https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.builder.jwtbeareroptions?view=aspnetcore-1.1.

如何配置 JWT 身份验证以从名为“AccessToken”的标头读取 JWT？是否可以使用 Microsoft.AspNetCore.Authentication.JwtBearer 包？

解决方案似乎是使用JwtBearerEvents 类 https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.authentication.jwtbearer.jwtbearerevents?view=aspnetcore-5.0。里面有一个代表名为 OnMessageReceived 的属性 https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.authentication.jwtbearer.jwtbearerevents.onmessagereceived?view=aspnetcore-5.0#Microsoft_AspNetCore_Authentication_JwtBearer_JwtBearerEvents_OnMessageReceived它是“首次收到协议消息时调用的”。委托将传递一个类型为消息接收上下文 https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.authentication.jwtbearer.messagereceivedcontext?view=aspnetcore-5.0，其中它有一个名为 Token 的属性根据文档 https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.authentication.jwtbearer.messagereceivedcontext?view=aspnetcore-5.0 “这将使应用程序有机会从替代位置检索令牌”.

创建一个继承自 JwtBearerEvents 的类，并在 OnMessageReceived 事件中将上下文对象中的令牌设置为标头“AccessToken”中的值。

/// <summary>
/// Singleton class handler of events related to JWT authentication
/// </summary>
public class AuthEventsHandler : JwtBearerEvents
{
    private const string BearerPrefix = "Bearer ";

    private AuthEventsHandler() => OnMessageReceived = MessageReceivedHandler;

    /// <summary>
    /// Gets single available instance of <see cref="AuthEventsHandler"/>
    /// </summary>
    public static AuthEventsHandler Instance { get; } = new AuthEventsHandler();

    private Task MessageReceivedHandler(MessageReceivedContext context)
    {
        if (context.Request.Headers.TryGetValue("AccessToken", out StringValues headerValue))
        {
            string token = headerValue;
            if (!string.IsNullOrEmpty(token) && token.StartsWith(BearerPrefix))
            {
                token = token.Substring(BearerPrefix.Length);
            }

            context.Token = token;
        }

        return Task.CompletedTask;
    }
}

最后，将事件类添加到 Startup 类的 JWT 身份验证中。

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(JwtBearerDefaults.AuthenticationScheme, options => 
{
    Configuration.Bind("JwtSettings", options);
    options.Events = AuthEventsHandler.Instance;
});