使用Jwt为.Net Core SignalR保驾护航

前言

　　SignalR Demo搭建起来之后，是没有相应的认证和授权功能的。于是乎，参考官方文档实现了相应的逻辑。

简单认证

　　首先使用稍微简单的方式实现。添加如下代码：

　services.AddAuthentication(auth =>
           {
                auth.DefaultScheme = "User";
           }).AddScheme<UserAuthenticationOptions, UserAuthenticationHandler>("User", o => { });

 public class UserAuthenticationOptions : AuthenticationSchemeOptions
    {
      
    }

　　然后在新增Handler，重写 AuthenticationHandler 的HandleAuthenticateAsync 方法

  public class UserAuthenticationHandler : AuthenticationHandler<UserAuthenticationOptions>
    {
        private readonly ILayIMUserFactory userFactory;

        public UserAuthenticationHandler(IOptionsMonitor<UserAuthenticationOptions> options, ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock, IServiceProvider serviceProvider)
        : base(options, logger, encoder, clock)
        {
            userFactory = serviceProvider.GetService<ILayIMUserFactory>();
        }
        protected override Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            var userId = userFactory.GetUserId(Request.HttpContext);
            if (string.IsNullOrEmpty(userId))
            {
                return Task.FromResult(AuthenticateResult.Fail("no user"));
            }
            var claims = new[] { new Claim("user", userId) };
            var identity = new ClaimsIdentity(claims, nameof(UserAuthenticationHandler));
            var ticket = new AuthenticationTicket(new ClaimsPrincipal(identity), Scheme.Name);
            return Task.FromResult(AuthenticateResult.Success(ticket));
        }
    }

　　最后在Hub上增加AuthorizeAttribute即可

 [Authorize(AuthenticationSchemes = “User”)]
 public class LayIMHub : Hub<ILayIMClient>{}

JWT Bearer认证

　　首先安装 Microsoft.AspNetCore.Authentication.JwtBearer .

　　然后在Startup中增加如下代码：（基本上就是官方教程中的）

 services.AddAuthentication(options =>
            {
                options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
                options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
            })
            .AddJwtBearer(options =>
            {
                options.TokenValidationParameters =
                    new TokenValidationParameters
                    {
                        LifetimeValidator = (before, expires, token, param) =>
                        {
                            return expires > DateTime.UtcNow;
                        },
                        ValidateAudience = false,
                        ValidateIssuer = false,
                        ValidateActor = false,
                        ValidateLifetime = true,
                        IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(SignalRSecurityKey.TOKEN_KEY))
                    };
                options.Events = new JwtBearerEvents
                {
                    OnMessageReceived = context =>
                    {
                        var accessToken = context.Request.Query["access_token"];

                        var path = context.HttpContext.Request.Path;
                        if (!string.IsNullOrEmpty(accessToken) &&
                            (path.StartsWithSegments("/layimHub")))
                        {
                            context.Token = accessToken;
                        }
                        return Task.CompletedTask;
                    }
                };
            });

　　不过AuthorizeAttribute 的Scheme 要改成 JwtBearerDefaults.AuthenticationScheme. 运行一下程序，因为刚开始没有提供token，所以肯定是401的。

　　对了，客户端连接的时候要加上accessTokenFactory：

 　　　　　　　var options = {};
            options.accessTokenFactory = () => token;
            //options.skipNegotiation = true;
            connection = new signalR.HubConnectionBuilder()
                .configureLogging(signalR.LogLevel.Trace)
                .withUrl(hubRoute, options)
                .withHubProtocol(protocol)
                .build();

　　我们在实现一个获取Token的接口，在调用SignalR连接之前，先获取Token，然后把token带上即可。以下代码是生成Token的方法，Subject的内容可以随便定义

 　　　　　　var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.ASCII.GetBytes(SignalRSecurityKey.TOKEN_KEY);
            var authTime = DateTime.UtcNow;
            var expiresAt = authTime.AddDays(7);
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new Claim[]
                {
                   new Claim("uid",userId)
                }),
                Expires = expiresAt,
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
            };
            var token = tokenHandler.CreateToken(tokenDescriptor);
            var tokenString = tokenHandler.WriteToken(token);
            return tokenString;

　　下面在看演示：