IdentitySeverのテンプレートisuiで吐き出された内容をみていく Part1

// Index.cshtml.cs
using Duende.IdentityServer;
using Duende.IdentityServer.Events;
using Duende.IdentityServer.Models;
using Duende.IdentityServer.Services;
using Duende.IdentityServer.Stores;
using Duende.IdentityServer.Test;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;

namespace IdentityServer.Pages.Create;

[SecurityHeaders]
[AllowAnonymous]
public class Index : PageModel
{
    private readonly TestUserStore _users;
    private readonly IIdentityServerInteractionService _interaction;

    [BindProperty]
    public InputModel Input { get; set; }
        
    public Index(
        IIdentityServerInteractionService interaction,
        TestUserStore users = null)
    {
        // this is where you would plug in your own custom identity management library (e.g. ASP.NET Identity)
        _users = users ?? throw new Exception("Please call 'AddTestUsers(TestUsers.Users)' on the IIdentityServerBuilder in Startup or remove the TestUserStore from the AccountController.");
            
        _interaction = interaction;
    }

    public IActionResult OnGet(string returnUrl)
    {
        Input = new InputModel { ReturnUrl = returnUrl };
        return Page();
    }
        
    public async Task<IActionResult> OnPost()
    {
        // check if we are in the context of an authorization request
        var context = await _interaction.GetAuthorizationContextAsync(Input.ReturnUrl);

        // the user clicked the "cancel" button
        if (Input.Button != "create")
        {
            if (context != null)
            {
                // if the user cancels, send a result back into IdentityServer as if they 
                // denied the consent (even if this client does not require consent).
                // this will send back an access denied OIDC error response to the client.
                await _interaction.DenyAuthorizationAsync(context, AuthorizationError.AccessDenied);

                // we can trust model.ReturnUrl since GetAuthorizationContextAsync returned non-null
                if (context.IsNativeClient())
                {
                    // The client is native, so this change in how to
                    // return the response is for better UX for the end user.
                    return this.LoadingPage(Input.ReturnUrl);
                }

                return Redirect(Input.ReturnUrl);
            }
            else
            {
                // since we don't have a valid context, then we just go back to the home page
                return Redirect("~/");
            }
        }

        if (_users.FindByUsername(Input.Username) != null)
        {
            ModelState.AddModelError("Input.Username", "Invalid username");
        }

        if (ModelState.IsValid)
        {
            var user = _users.CreateUser(Input.Username, Input.Password, Input.Name, Input.Email);

            // issue authentication cookie with subject ID and username
            var isuser = new IdentityServerUser(user.SubjectId)
            {
                DisplayName = user.Username
            };

            await HttpContext.SignInAsync(isuser);

            if (context != null)
            {
                if (context.IsNativeClient())
                {
                    // The client is native, so this change in how to
                    // return the response is for better UX for the end user.
                    return this.LoadingPage(Input.ReturnUrl);
                }

                // we can trust model.ReturnUrl since GetAuthorizationContextAsync returned non-null
                return Redirect(Input.ReturnUrl);
            }

            // request for a local page
            if (Url.IsLocalUrl(Input.ReturnUrl))
            {
                return Redirect(Input.ReturnUrl);
            }
            else if (string.IsNullOrEmpty(Input.ReturnUrl))
            {
                return Redirect("~/");
            }
            else
            {
                // user might have clicked on a malicious link - should be logged
                throw new Exception("invalid return URL");
            }
        }

        return Page();
    }
}

// InputModel.cs
using System.ComponentModel.DataAnnotations;

namespace IdentityServer.Pages.Create;

public class InputModel
{
    [Required]
    public string Username { get; set; }

    [Required]
    public string Password { get; set; }

    public string Name { get; set; }
    public string Email { get; set; }

    public string ReturnUrl { get; set; }

    public string Button { get; set; }
}