.net core 3.0 Signalr – 05 使用jwt将用户跟signalr关联

signalr是以group、connect为核心来进行推送，比如，给某个组、某个连接来推送，但实际场景中，核心应该是某个组、某个人；然而一个人可以对应多个连接(浏览器多个tab页)；本节就来介绍下自行管理人、组、连接这些关系
由于signalr连接的时候不那么方便附带header和cookie(因为推送独立成一个子系统了)，实际实现中采用以url query的形式附带上token，然后服务器端自定义解析token得到用户信息；

服务器端实现

• configureservices中添加服务相关方法，代码如下,完整代码

  public void configureservices(iservicecollection services)
  {
      var appsection = configuration.getsection("app");
      services.configure<appsetting>(option => appsection.bind(option));
      var appsetting = appsection.get<appsetting>();
  
      services.addsingleton<signalrredishelper>();
  
      // services.addhostedservice<clearbackgroundservice>();
  
      services.addauthentication(options =>
      {
          options.defaultauthenticatescheme = jwtbearerdefaults.authenticationscheme;
          options.defaultchallengescheme = jwtbearerdefaults.authenticationscheme;
          options.defaultforbidscheme = jwtbearerdefaults.authenticationscheme;
      })
      .addjwtbearer(option =>
      {
          option.securitytokenvalidators.clear();
          option.securitytokenvalidators.add(new usertokenvalidation()); ;
  
          option.events = new jwtbearerevents()
          {
              onmessagereceived = context =>
              {
                  var userid = context.request.query["userid"].firstordefault();
                  if (!string.isnullorwhitespace(userid))
                  {
                      context.token = userid;
                  }
                  return task.completedtask;
              }
          };
      });
  
      services.addcors(options => options.addpolicy(corspolicy, builder =>
      {
          builder
                .setisoriginallowedtoallowwildcardsubdomains()
                .withorigins(appsetting.cors.split(","))
                .allowanymethod()
                .allowcredentials()
                .allowanyheader()
                .build();
      }));
  
      services.addcontrollers()
          .addnewtonsoftjson(options => options.serializersettings.contractresolver = new camelcasepropertynamescontractresolver())
          .configureapibehavioroptions(options =>
          {
              options.invalidmodelstateresponsefactory = context =>
              {
                  var result = new badrequestobjectresult(context.modelstate);
                  result.contenttypes.add(mediatypenames.application.json);
                  // result.contenttypes.add(mediatypenames.application.xml);
  
                  return result;
              };
          })
          .setcompatibilityversion(compatibilityversion.version_3_0);
  
      // 添加signalr
      services.addsignalr(config =>
      {
          if (_webenv.isdevelopment())
          {
              config.enabledetailederrors = true;
          }
      })
      // 支持messagepack
      .addmessagepackprotocol()
      // 使用redis做底板 支持横向扩展 scale-out
      .addstackexchangeredis(o =>
        {
            o.connectionfactory = async writer =>
            {
                var config = new configurationoptions
                {
                    abortonconnectfail = false,
                    // password = "changeme",
                    channelprefix = "__signalr_",
                };
                //config.endpoints.add(ipaddress.loopback, 0);
                //config.setdefaultports();
                config.defaultdatabase = appsetting.signalrrediscache.databaseid;
                var connection = await connectionmultiplexer.connectasync(appsetting.signalrrediscache.connectionstring, writer);
                connection.connectionfailed += (_, e) =>
                {
                    console.writeline("connection to redis failed.");
                };
  
                if (connection.isconnected)
                {
                    console.writeline("connected to redis.");
                }
                else
                {
                    console.writeline("did not connect to redis");
                }
  
                return connection;
            };
        });
  }

  其中，signalrredishelper 为redis辅助方法，详情请参见
  usertokenvalidation 为自定义token解析方法，详情请参见,由于历史遗留问题，此处直接使用了userid，建议的做法是传递jwttoken，然后服务器端解析jwt token得到用户信息

hub中跟用户关联

在hub中通过context.user.identity.name可以获取到解析的值，通过这种关系来跟用户关联上，当然，也可以自定义修改使用其他信息，比如email或其他自定义的名称，具体请google

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