How to get user name for Blazor server applications (EasyAuth)?

Question

I configured azure app service using EasyAuth.

I tried to get the user name in the article below, but the username was returned null.

The EasyAuth is working correctly.

https://learn.microsoft.com/en-us/aspnet/core/blazor/security/server/additional-scenarios?view=aspnetcore-7.0#circuit-handler-to-capture-users-for-custom-services

How do I get it??

Answer 1

Hi @takeolexus,

I have found a workaround for this issue, and I could share with you. And I am still waiting for app service expert's reply.

Program.cs

using BlazorServerEasyAuth.Data;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.AspNetCore.Components.Server;
using Microsoft.AspNetCore.Components.Server.Circuits;
using Microsoft.AspNetCore.Components.Web;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Newtonsoft.Json.Linq;
using System.Net;
using System.Security.Claims;
using System.Security.Principal;

namespace BlazorServerEasyAuth
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);

            // Add services to the container.
            builder.Services.AddRazorPages();
            builder.Services.AddServerSideBlazor();
            builder.Services.AddSingleton<WeatherForecastService>();

            builder.Services.AddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();

            var app = builder.Build();

            // Configure the HTTP request pipeline.
            if (!app.Environment.IsDevelopment())
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();

            app.UseStaticFiles();

            app.Use(async (context, next) =>
            {
                // Create a user on current thread from provided header
                if (context.Request.Headers.ContainsKey("X-MS-CLIENT-PRINCIPAL-ID"))
                {
                    // Read headers from Azure
                    var azureAppServicePrincipalIdHeader = context.Request.Headers["X-MS-CLIENT-PRINCIPAL-ID"][0];
                    var azureAppServicePrincipalNameHeader = context.Request.Headers["X-MS-CLIENT-PRINCIPAL-NAME"][0];

                    #region extract claims via call /.auth/me
                    //invoke /.auth/me
                    var cookieContainer = new CookieContainer();
                    HttpClientHandler handler = new HttpClientHandler()
                    {
                        CookieContainer = cookieContainer
                    };
                    string uriString = $"{context.Request.Scheme}://{context.Request.Host}";
                    foreach (var c in context.Request.Cookies)
                    {
                        cookieContainer.Add(new Uri(uriString), new Cookie(c.Key, c.Value));
                    }
                    string jsonResult = string.Empty;
                    using (HttpClient client = new HttpClient(handler))
                    {
                        var res = await client.GetAsync($"{uriString}/.auth/me");
                        jsonResult = await res.Content.ReadAsStringAsync();
                    }

                    //parse json
                    var obj = JArray.Parse(jsonResult);
                    string user_id = obj[0]["user_id"].Value<string>(); //user_id

                    // Create claims id
                    List<Claim> claims = new List<Claim>();
                    foreach (var claim in obj[0]["user_claims"])
                    {
                        claims.Add(new Claim(claim["typ"].ToString(), claim["val"].ToString()));
                    }

                    // Set user in current context as claims principal
                    var identity = new GenericIdentity(azureAppServicePrincipalNameHeader);
                    identity.AddClaims(claims);
                    #endregion

                    // Set current thread user to identity
                    context.User = new GenericPrincipal(identity, null);
                };

                await next.Invoke();
            });

            app.UseRouting();



            app.MapBlazorHub();
            app.MapFallbackToPage("/_Host");

            app.Run();
        }
    }
}

Index.razor

@page "/"
@using System.Security.Claims;
@inject AuthenticationStateProvider AuthenticationStateProvider

<h1>Hello, @UserName!</h1>

@code {
    private string? UserName;

    protected override async Task OnInitializedAsync()
    {
        var authenticationState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
        var user = authenticationState.User;

        if (user.Identity.IsAuthenticated)
        {
            // Find the user's name claim
            var userNameClaim = user.FindFirst(ClaimTypes.Name);
            if (userNameClaim != null)
            {
                UserName = userNameClaim.Value;
            }
        }
    }
}

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Best regards,
Jason