webapi身份验证

public class HTTPBasicAuthorizeAttribute : System.Web.Http.AuthorizeAttribute
    {
        public override void OnAuthorization(System.Web.Http.Controllers.HttpActionContext actionContext)
        {
            try
            {
                //用户名
                IEnumerable<string> account = actionContext.Request.Headers.GetValues("account");
                List<string> accountlist = account.ToList();
                //密码
                //IEnumerable<string> password = actionContext.Request.Headers.GetValues("password");
                //List<string> passwordlist = password.ToList();


                //string username = Encoding.Default.GetString(Convert.FromBase64String(accountlist[0]));
                //string pwd = Encoding.Default.GetString(Convert.FromBase64String(passwordlist[0]));
                PetaPoco.Database db = new PetaPoco.Database("DefaultConnection");
                int linkinfo = db.ExecuteScalar<int>(string.Format(@"select * from (select  right(sys.fn_VarBinToHexStr(hashbytes('MD5',UserName+Password)),32) as userinfo from LinkInfo) as t
                                                        where userinfo = '{0}'", accountlist[0]));

                //用户验证逻辑
                if (linkinfo != null)
                {
                    IsAuthorized(actionContext);
                }
                else
                {
                    HandleUnauthorizedRequest(actionContext);
                }

            }
            catch (Exception)
            {

                HandleUnauthorizedRequest(actionContext);
            }

        }

        protected override void HandleUnauthorizedRequest(System.Web.Http.Controllers.HttpActionContext actionContext)
        {
            var challengeMessage = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.Unauthorized);
            challengeMessage.Headers.Add("WWW-Authenticate", "Basic");
            throw new System.Web.Http.HttpResponseException(challengeMessage);

        }
    }