开源项目葫芦藤：IdentityServer4的实现及其运用

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本篇文章主要是讲解葫芦藤项目中对IdentityServer的实践使用，为了使您对本篇文章中所讲述的内容有深刻的认识，并且在阅读时避免感到乏味，文中的内容不会涉及太多的基础理论知识，而更多的是采用动手实践的方式进行讲解，所以在阅读此篇文章前假定您已经掌握了OAuth2.0的基础知识，如您事先并未了解OAuth2.0，请参阅一下阮一峰老师的文章《理解OAuth2.0》， ASP.NET Core 认证与授权，可以看看博客 雨夜朦胧，另外IdentityServer的相关文章也可以参考博客 晓晨Master。

葫芦藤前端地址：https://account.suuyuu.cn （验证码获取后，输入123456即可）

葫芦藤后端地址：https://account-web.suuyuu.cn

葫芦藤源码地址：https://github.com/fuluteam/fulusso （帮忙点个小星星哦）

团队博文地址：https://www.cnblogs.com/fulu

签名证书（Signing Credential）

IdentityServer支持X.509证书(包括原始文件和对Windows证书存储库的引用)、RSA密钥和EC密钥，用于令牌签名和验证。每个密钥都可以配置一个(兼容的)签名算法，如RS256、RS384、RS512、PS256、PS384、PS512、ES256、ES384或ES512。

通常情况下，我们使用的是针对开发场景创建的临时证书 AddDeveloperSigningCredential，
生产环境怎么办呢？IdentityServer还提供了AddSigningCredential用来装载证书文件，
为此我们需要准备一个X.509证书，下面是在控制台项目中用于生成证书的代码，完整代码请参考项目：https://github.com/fuluteam/ICH.BouncyCastle

//颁发者DN
var issuer = new X509Name(
new ArrayList{X509Name.C,X509Name.O,X509Name.OU,X509Name.L,X509Name.ST}, 
new Hashtable{[X509Name.C] = "CN",[X509Name.O] = "Fulu Newwork",[X509Name.OU] = "Fulu RSA CA 2020",[X509Name.L] = "Wuhan",[X509Name.ST] = "Hubei"});
//使用者DN
var subject = new X509Name(new ArrayList{X509Name.C,X509Name.O,X509Name.CN}, new Hashtable {[X509Name.C] = "CN",[X509Name.O] = "ICH",[X509Name.CN] = "*.fulu.com"});

//生成证书文件
CertificateGenerator.GenerateCertificate(newCertificateGenerator.GenerateCertificateOptions { Path = "mypfx.pfx",Issuer = issuer, Subject = subject });

执行代码后，在项目编译输出目录中，会看到一个mypfx.pfx的文件，此时我们的证书就创建成功啦。
接着怎么使用呢，看下面代码：

var certificate2 = new X509Certificate2("mypfx.pfx", "password", X509KeyStorageFlags.Exportable);
identityServerBuilder.AddSigningCredential(certificate2);

大家可能会问，葫芦藤中怎么不是这么写的呢，其实葫芦藤项目中是将证书文件的流数据转成了二进制字符串，这样就可以写在配置文件中了：

using (var fs = new FileStream(options.Path, FileMode.Open))
{
    var bytes = new byte[fs.Length];
    fs.Read(bytes, 0, bytes.Length);
    var pfxHexString = Hex.ToHexString(bytes);
}

然后在这么使用：

identityServerBuilder.AddSigningCredential(new X509Certificate2(Hex.Decode(appSettings.X509RawCertData), appSettings.X509CertPwd));

客户端存储（Client Store）

在葫芦藤项目中，我们创建了一个ClientStore类，继承自接口IClientStore，实现其方法代码如下：

public class ClientStore : IClientStore
{
    private readonly IClientCacheStrategy _clientInCacheRepository;

    public ClientStore(IClientCacheStrategy clientInCacheRepository)
    {
        _clientInCacheRepository = clientInCacheRepository;
    }
    public async Task<Client> FindClientByIdAsync(string clientId)
    {

        var clientEntity = await _clientInCacheRepository.GetClientByIdAsync(clientId.ToInt32());
        if (clientEntity == null)
        {
            return null;
        }
        return new Client
        {
            ClientId = clientId,
            AllowedScopes = new[] { "api", "get_user_info" },
            ClientSecrets = new[] { new Secret(clientEntity.ClientSecret.Sha256()) },
            AllowedGrantTypes = new[]
            {
                GrantType.AuthorizationCode,    //授权码模式
                GrantType.ClientCredentials,    //客户端模式
                GrantType.ResourceOwnerPassword,    //密码模式
                CustomGrantType.External,   //自定义模式——三方（移动端）模式
                CustomGrantType.Sms //自定义——短信模式
            },
            AllowOfflineAccess = false,
            RedirectUris = string.IsNullOrWhiteSpace(clientEntity.RedirectUri) ? null : clientEntity.RedirectUri.Split(';'),
            RequireConsent = false,
            AccessTokenType = AccessTokenType.Jwt,
            AccessTokenLifetime = 7200,
            ClientClaimsPrefix = "",
            Claims = new[] { new Claim(JwtClaimTypes.Role, "Client") }
        };
    }
}

通过代码可以看到，通过clientId从缓存中读取Client的相关信息构建并返回，这里我们为所有的Client简单的设置了统一的AllowedGrantTypes，这是一种偷懒的做法，应当按需授予GrantType，例如通常情况下我们只应默认给应用分配AuthorizationCode或者ClientCredentials，ResourceOwnerPassword需要谨慎授予（需要用户对Client高度信任）。

资源存储（Resource Store）

由于历史原因，在葫芦藤中，我们并没有通过IdentityServer对api资源进行访问保护（后续会提供我们的实现方式），我们为所有Client设置了相同的Scope。

持久化授权存储（Persisted Grant Store）

葫芦藤中，我们使用了Redis来持久化数据，

通过EntityFramework Core持久化配置和操作数据，请参考
https://www.cnblogs.com/stulzq/p/8120518.html
https://github.com/IdentityServer/IdentityServer4.EntityFramework

IPersistedGrantStore接口中定义了如下6个方法：

/// <summary>Interface for persisting any type of grant.</summary>
public interface IPersistedGrantStore
{
  /// <summary>Stores the grant.</summary>
  /// <param name="grant">The grant.</param>
  /// <returns></returns>
  Task StoreAsync(PersistedGrant grant);

  /// <summary>Gets the grant.</summary>
  /// <param name="key">The key.</param>
  /// <returns></returns>
  Task<PersistedGrant> GetAsync(string key);

  /// <summary>Gets all grants for a given subject id.</summary>
  /// <param name="subjectId">The subject identifier.</param>
  /// <returns></returns>
  Task<IEnumerable<PersistedGrant>> GetAllAsync(string subjectId);

  /// <summary>Removes the grant by key.</summary>
  /// <param name="key">The key.</param>
  /// <returns></returns>
  Task RemoveAsync(string key);

  /// <summary>
  /// Removes all grants for a given subject id and client id combination.
  /// </summary>
  /// <param name="subjectId">The subject identifier.</param>
  /// <param name="clientId">The client identifier.</param>
  /// <returns></returns>
  Task RemoveAllAsync(string subjectId, string clientId);

  /// <summary>
  /// Removes all grants of a give type for a given subject id and client id combination.
  /// </summary>
  /// <param name="subjectId">The subject identifier.</param>
  /// <param name="clientId">The client identifier.</param>
  /// <param name="type">The type.</param>
  /// <returns></returns>
  Task RemoveAllAsync(string subjectId, string clientId, string type);
}

PersistedGrant的结构如下：

/// <summary>A model for a persisted grant</summary>
public class PersistedGrant
{
  /// <summary>Gets or sets the key.</summary>
  /// <value>The key.</value>
  public string Key { get; set; }

  /// <summary>Gets the type.</summary>
  /// <value>The type.</value>
  public string Type { get; set; }

  /// <summary>Gets the subject identifier.</summary>
  /// <value>The subject identifier.</value>
  public string SubjectId { get; set; }

  /// <summary>Gets the client identifier.</summary>
  /// <value>The client identifier.</value>
  public string ClientId { get; set; }

  /// <summary>Gets or sets the creation time.</summary>
  /// <value>The creation time.</value>
  public DateTime CreationTime { get; set; }

  /// <summary>Gets or sets the expiration.</summary>
  /// <value>The expiration.</value>
  public DateTime? Expiration { get; set; }

  /// <summary>Gets or sets the data.</summary>
  /// <value>The data.</value>
  public string Data { get; set; }
}

可以看出主要是针对PersistedGrant对象的操作，通过观察GetAsync和RemoveAsync方法的入参均为key，我们在StoreAsync中将PersistedGrant中的Key作为缓存key，将PersistedGrant对象以hash的方式存入缓存中，并设置过期时间（注意将UTC时间转换为本地时间）

public async Task StoreAsync(PersistedGrant grant)
{
    //var expiresIn = grant.Expiration - DateTimeOffset.UtcNow;
    var db = await _redisCache.GetDatabaseAsync();

    var trans = db.CreateTransaction();

    var expiry = grant.Expiration.Value.ToLocalTime();

    db.HashSetAsync(grant.Key, GetHashEntries(grant));  //GetHashEntries是将对象PersistedGrant转换为HashEntry数组
    db.KeyExpireAsync(grant.Key, expiry);
    await trans.ExecuteAsync();
}

同时，把GetAsync和RemoveAsync的代码填上：

public async Task<PersistedGrant> GetAsync(string key)
{
    var db = await _redisCache.GetDatabaseAsync();
    var items = await db.HashGetAllAsync(key);
    return GetPersistedGrant(items);    //将HashEntry数组转换为PersistedGrant对象
}

public async Task RemoveAsync(string key)
{
    var db = await _redisCache.GetDatabaseAsync();
    await db.KeyDeleteAsync(key);
}

接着，GetAllAsync方法，通过subjectId查询PersistedGrant集合，1对n，因此，我们在StoreAsync中补上这一层关系，以subjectId为缓存key，grant.Key为缓存值存入list集合中；GetAllAsync方法中，通过subjectId取出grant.Key的集合，最终得到PersistedGrant集合。

public async Task StoreAsync(PersistedGrant grant)
{
    //var expiresIn = grant.Expiration - DateTimeOffset.UtcNow;
    var db = await _redisCache.GetDatabaseAsync();

    var trans = db.CreateTransaction();

    var expiry = grant.Expiration.Value.ToLocalTime();

    db.HashSetAsync(grant.Key, GetHashEntries(grant));  //GetHashEntries是将对象PersistedGrant转换为HashEntry数组
    db.KeyExpireAsync(grant.Key, expiry);
    
    db.ListLeftPushAsync(grant.SubjectId, grant.Key);
    db.KeyExpireAsync(grant.SubjectId, expiry);
                
    await trans.ExecuteAsync();
}

public async Task<IEnumerable<PersistedGrant>> GetAllAsync(string subjectId)
{
    if (string.IsNullOrWhiteSpace(subjectId))
        return new List<PersistedGrant>();

    var db = await _redisCache.GetDatabaseAsync();

    var keys = await db.ListRangeAsync(subjectId);

    var list = new List<PersistedGrant>();
    foreach (string key in keys)
    {
        var items = await db.HashGetAllAsync(key);
        list.Add(GetPersistedGrant(items));
    }

    return list;
}

类似的，StoreAsync方法中我们只需StoreAsync方法中根据RemoveAllAsync方法参数组装缓存key，grant.Key为缓存值写入缓存，对应的RemoveAllAsync中根据参数组装的key查询出grant.Key集合，删除缓存即可。

public async Task StoreAsync(PersistedGrant grant)
{
    var db = await _redisCache.GetDatabaseAsync();

    var trans = db.CreateTransaction();

    var expiry = grant.Expiration.Value.ToLocalTime();

    db.HashSetAsync(grant.Key, GetHashEntries(grant));
    db.KeyExpireAsync(grant.Key, expiry);

    if (!string.IsNullOrEmpty(grant.SubjectId))
    {
        db.ListLeftPushAsync(grant.SubjectId, grant.Key);
        db.KeyExpireAsync(grant.SubjectId, expiry);

        var key1 = $"{grant.SubjectId}:{grant.ClientId}";
        db.ListLeftPushAsync(key1, grant.Key);
        db.KeyExpireAsync(key1, expiry);

        var key2 = $"{grant.SubjectId}:{grant.ClientId}:{grant.Type}";
        db.ListLeftPushAsync(key2, grant.Key);
        db.KeyExpireAsync(key2, expiry);
    }

    await trans.ExecuteAsync();
}

public async Task RemoveAllAsync(string subjectId, string clientId)
{
    if (string.IsNullOrEmpty(subjectId) || string.IsNullOrEmpty(clientId))
        return;
    var db = await _redisCache.GetDatabaseAsync();

    var key = $"{subjectId}:{clientId}";
    var keys = await db.ListRangeAsync(key);
    if (!keys.Any()) return;

    var trans = db.CreateTransaction();
    db.KeyDeleteAsync(keys.ToRedisKeys());
    db.KeyDeleteAsync(key);
    await trans.ExecuteAsync();
}

public async Task RemoveAllAsync(string subjectId, string clientId, string type)
{
    if (string.IsNullOrEmpty(subjectId) || string.IsNullOrEmpty(clientId) || string.IsNullOrEmpty(type))
        return;
    var db = await _redisCache.GetDatabaseAsync();

    var key = $"{subjectId}:{clientId}:{type}";
    var keys = await db.ListRangeAsync(key);
    if (!keys.Any()) return;

    var trans = db.CreateTransaction();
    db.KeyDeleteAsync(keys.ToRedisKeys());
    db.KeyDeleteAsync(key);
    await trans.ExecuteAsync();
}

至此，持久化的代码填写完毕；启动并调试项目，可以看到PersistedGrant对象如下：

资源拥有者验证器（Resource Owner Validator）

如果要使用OAuth 2.0 密码模式（Resource Owner Password Credentials Grant），则需要实现并注册IResourceOwnerPasswordValidator接口：

public async Task ValidateAsync(ResourceOwnerPasswordValidationContext context)
{
    var result = await _userService.LoginByPasswordAsync(context.UserName, context.Password);
    if (result.Code == 0)
    {
        var claims = await _userService.SaveSuccessLoginInfo(context.Request.ClientId.ToInt32(), result.Data.Id,
         _contextAccessor.HttpContext.GetIp(), UserLoginModel.Password);
        context.Result = new GrantValidationResult(result.Data.Id, OidcConstants.AuthenticationMethods.Password, claims);
    }
    else
    {
        context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, result.Message);
    }
}

重定向地址验证器（Redirect Uri Validator）

用于验证重定向（授权码模式）和注销后重定向Uri的校验，葫芦藤项目中重定向地址验证只验证域名（不验证完整的requestedUri地址），且未进行注销重定向Uri的校验。

public class RedirectUriValidator : IRedirectUriValidator
{
    public Task<bool> IsRedirectUriValidAsync(string requestedUri, Client client)
    {
        if (client.RedirectUris == null || !client.RedirectUris.Any())
        {
            return Task.FromResult(false);
        }
        var uri = new Uri(requestedUri);
        return Task.FromResult(client.RedirectUris.Any(x => x.Contains(uri.Host)));
    }

    public Task<bool> IsPostLogoutRedirectUriValidAsync(string requestedUri, Client client)
    {
        return Task.FromResult(true);
    }
}

扩展授权验证器（Extension Grant Validator）

在IdentityServer4中，通过实现IExtensionGrantValidator接口，可以实现自定义授权。在葫芦藤项目中，我们有两个场景需要用到自定义授权：

• 通过第三方（QQ、微信）的用户标识（OpenId）进行登录（颁发用户令牌）
• 通过短信验证码进行登录（颁发用户令牌）

在IdentityServer4中实现短信验证码授权模式，我们创建了一个SmsGrantValidator类，继承自IExtensionGrantValidator接口，然后给属性GrantType取一个名字，此处名称为“sms”，实现ValidateAsync方法，方法内进行入参校验，然后验证短信验证码，验证通过后取出用户信息，下面代码中，当用户不存在时也可以自动注册。代码如下：

public class SmsGrantValidator : IExtensionGrantValidator
{
    private readonly IHttpContextAccessor _contextAccessor;
    private readonly IValidationComponent _validationComponent;
    private readonly IUserService _userService;

    public SmsGrantValidator(IHttpContextAccessor contextAccessor, IValidationComponent validationComponent, IUserService userService)
    {
        _contextAccessor = contextAccessor;
        _validationComponent = validationComponent;
        _userService = userService;
        GrantType = CustomGrantType.Sms;
    }

    public async Task ValidateAsync(ExtensionGrantValidationContext context)
    {
        var phone = context.Request.Raw.Get("phone");
        var code = context.Request.Raw.Get("code");
        if (string.IsNullOrEmpty(phone) || Regex.IsMatch(phone, RegExp.PhoneNumber) == false)
        {
            context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, "phone is not valid");
            return;
        }
        if (string.IsNullOrEmpty(code))
        {
            context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, "code is not valid");
            return;
        }

        try
        {
            var validSms = await _validationComponent.ValidSmsAsync(phone, code);
            if (!validSms.Data)
            {
                context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, validSms.Message);
                return;
            }

            var userEntity = await _userService.GetUserByPhoneAsync(phone);
            if (userEntity == null)
            {
                context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, "用户不存在或未注册");
                return;
            }
            if (userEntity.Enabled == false)
            {
                context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, "您的账号已被禁止登录");
                return;
            }

            await _userService.SaveSuccessLoginInfo(context.Request.ClientId.ToInt32(), userEntity.Id, _contextAccessor.HttpContext.GetIp(),
                 UserLoginModel.SmsCode);
        }
        catch (Exception ex)
        {
            context.Result = new GrantValidationResult(TokenRequestErrors.InvalidRequest, ex.Message);
        }
    }

    public string GrantType { get; }
}

OAuth2.0的实践运用场景

基于角色的授权（role-based authorization）

基于角色的授权检查是声明性的，开发人员将其嵌入到代码中、控制器或控制器内的操作，指定当前用户必须是其成员的角色才能访问请求的资源，文档参考《ASP.NET Core 中的基于角色的授权》。

葫芦藤中定义了两种角色Claim（声明），客户端和用户，使用客户端授权模式（client credentials）颁发的令牌，ClaimRole为Client，使用授权码模式（authorization code）、密码模式（resource owner password credentials）、自定义授权模式（短信、第三方）颁发的用户令牌，ClaimRole为User

public static class ClaimRoles
{
    /// <summary>
    /// 客户端
    /// </summary>
    public const string Client = "Client";
    /// <summary>
    /// 用户
    /// </summary>
    public const string User = "User";
}

在ClientStore中增加返回Client的Claims，JwtClaimTypes.Role为ClaimRoles.Client，下面是客户端令牌，可以看到 "role":"Client"

{"alg":"RS256","kid":"99AA0C1236097972F29789562761D38AAE301918","typ":"JWT","x5t":"maoMEjYJeXLyl4lWJ2HTiq4wGRg"}
{"nbf":1608522625,"exp":1608529825,"iss":"http://localhost:80","aud":"api","client_id":"10000001","role":"Client","scope":["api","get_user_info"]}

在用户登录成功后返回的Claims中增加JwtClaimTypes.Role为ClaimRoles.User，下面是用户令牌，可以看到 "role":"User"

{"alg":"RS256","kid":"99AA0C1236097972F29789562761D38AAE301918","typ":"JWT","x5t":"maoMEjYJeXLyl4lWJ2HTiq4wGRg"}
{"nbf":1608522576,"exp":1608529776,"iss":"http://localhost:80","aud":"api","client_id":"10000001","sub":"df09efff-0074-4dca-91c3-e38180c5e4ac","auth_time":1608522576,"idp":"local","id":"df09efff-0074-4dca-91c3-e38180c5e4ac","open_id":"07E8E30B56D256EF8C440019AB6AAA89","name":"1051dfd1-73e5-4e6f-9326-3423bc9b71a3","nickname":"laowang","phone_number":"18627131390","email":"","role":"User","login_ip":"0.0.0.1","login_address":"保留地址","last_login_ip":"0.0.0.1","last_login_address":"保留地址","scope":["api","get_user_info"],"amr":["pwd","mfa"]}

在项目Fulu.Passport.API的Startup文件中，添加对组件Fulu.Service.Authorize的服务注入

services.AddServiceAuthorize(o =>...代码省略...);

services.AddAuthentication(x =>...代码省略...).AddJwtBearer(o =>
{
    ...代码省略...
    o.TokenValidationParameters = new TokenValidationParameters
    {
        NameClaimType = JwtClaimTypes.Name,
        RoleClaimType = ClaimTypes.Role,    //注意，这里不能使用JwtClaimTypes.Role
    ...代码省略...
    }
}

接着，只需在Controller或Action上指定属性即可

[Route("api/[controller]/[action]")]
[ApiController]
[Authorize(Roles = ClaimRoles.Client)]
public class ClientController : ControllerBase
{
    ...省略部分代码...
    /// <summary>
    /// 获取应用列表
    /// </summary>
    /// <returns></returns>
    [HttpGet]
    [ProducesResponseType(typeof(ActionObjectResult<List<ClientEntity>, Statistic>), 200)]
    public async Task<IActionResult> GetClients()
    {
        var clients = await _clientRepository.TableNoTracking.Where(c => c.Enabled).ToListAsync();
        return ObjectResponse.Ok(clients);
    }
    ...省略部分代码...

客户端授权模式（client credentials）

通过客户端授权模式颁发的令牌，可以实现对服务资源进行保护。步骤如下：

（A）客户端10000001向葫后进行身份认证，并要求一个访问令牌。

（B）葫后验证客户端身份后，向客户端10000001提供访问令牌。

A步骤中，客户端10000001发出的HTTP请求，包含以下参数：

• grant_type：表示授权类型，此处的值固定为"clientcredentials"，必选项。
• client_id：表示客户端的ID，必选项。
• client_secret：表示客户端密钥，必选项。

POST https://account-web.suuyuu.cn/oauth/token HTTP/1.1
Host: www.xxx.com
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials&client_id=10000001&client_secret=14p9ao1gxu4q3sp8ogk8bq4gkct59t9w

B步骤中，葫芦藤向客户端10000001发放令牌，下面是一个例子。

HTTP/1.1 200 OK
Content-Type: application/json;charset=UTF-8
Cache-Control: no-store, no-cache, max-age=0
Pragma: no-cache

{
    "access_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6Ijk5QUEwQzEyMzYwOTc5NzJGMjk3ODk1NjI3NjFEMzhBQUUzMDE5MTgiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJtYW9NRWpZSmVYTHlsNGxXSjJIVGlxNHdHUmcifQ.eyJuYmYiOjE2MDc0MTQ2MjUsImV4cCI6MTYwNzQyMTgyNSwiaXNzIjoiaHR0cDovL2xvY2FsaG9zdDo4MCIsImF1ZCI6ImFwaSIsImNsaWVudF9pZCI6IjEwMDAwMDAxIiwicm9sZSI6IkNsaWVudCIsImh0dHA6Ly9zY2hlbWFzLm1pY3Jvc29mdC5jb20vd3MvMjAwOC8wNi9pZGVudGl0eS9jbGFpbXMvcm9sZSI6IkNsaWVudCIsInNjb3BlIjpbImFwaSIsImdldF91c2VyX2luZm8iXX0.ilu1qMxDiXVxsqU6aO-xuyYaLvvj2mxONjYkXtpMs46K7O3_Qc5VsY0ZZaYPoLROAqPulxsWWpxjEiQd10OdRh4IziGAcpYfAfoD80CZxrcuWrWloB5aWncv_PMZcjzKw7Vt3G3g-WkJl4amTta498hZJ3B-N-ReLhl-3ICSMFU8PU_ZVtEB-2lRx93rVyPIaQu_DWmpyW4Bdf2ocYm4RPQAEsvBToEFObbWPG6paLWIjrSN2aQPvsRWziorvlIhyFV5L6oyFIGIrZxdLJTOsvRQaevpV1sbv9pD_Z9PZDbSQiQDbWQv0MfrYB0Npc6VQlIMkL2GPNlQ8NgwyGT1sQ",
    "expires_in": 7200,
    "token_type": "Bearer",
    "scope": "api get_user_info"
}

授权码模式（authorization code）

葫芦藤项目通过授权码模式（authorization code）实现了单点登录，通过授权码模式拿到用户令牌。目前葫芦藤只有一个应用（葫芦藤安全中心），这里为了不把概念搞混淆，我们假定百度（客户端10000002，redirect_uri 为 http://www.baidu.com）接入了咱们的授权体系，当然，百度的前端肯定没有写如何构造请求步骤的逻辑代码，因此，我们下面通过人工模拟请求步骤。

• 葫芦藤的client_id是10000001，百度的client_id是10000002
• 葫芦藤前端服务，简称“葫前”（https://account.suuyuu.cn）
• 葫芦藤后端服务，简称“葫后”（https://account-web.suuyuu.cn）
• 百度前端服务，简称“百前”（https://www.baidu.com）
• 百度后端服务，简称“百后”（假定地址为 https://api.baidu.com）

（A）用户访问“百前”，“百前”将用户导向“葫后”。
（B）“葫后”检查用户是否需要登录（是否携带了有效的登录Cookie），如需登录跳转到“葫前”。
（C）用户登录后，“葫后”将用户导向百度事先指定的"重定向URI"（redirection URI），同时附上一个授权码。
（D）“百前”收到授权码，附上早先的"重定向URI"，向“百后”申请令牌，“百后”拿到授权码之后携带密钥client_secret向“葫后”申请令牌。
（E）“葫后”核对了授权码和重定向URI，确认无误后，向“百后”颁发访问令牌（access token）。
（F）“百后”将令牌返回给“百前”。

A步骤中，构造的请求地址包含以下参数：

• response_type：表示授权类型，必选项，此处的值固定为"code"
• client_id：表示客户端的ID，必选项
• redirect_uri：表示重定向URI，可选项
• scope：表示申请的权限范围，可选项
• state：表示客户端的当前状态，可以指定任意值，认证服务器会原封不动地返回这个值

步骤A中开发人员需向前端人员提供client_id，即上面的client_id，下面是一个例子。

构造如下地址，复制到浏览器地址栏中并回车，如果跳转到登录页，请进行登录。

https://account-web.suuyuu.cn/connect/authorize?client_id=10000002&redirect_uri=https%3A%2F%2Fwww.baidu.com&response_type=code&scope=api&state=STATE

登录后会重定向redirect_uri到如下地址：

https://www.baidu.com/?code=1MlxrvXuD7TfH-s4dLzcw9ymO0SKDbf5xAlh3ZEHlMo&scope=api&state=STATE

D步骤中，我们通过临时授权码向“葫后”索取令牌，包含以下参数：

• grant_type：表示使用的授权模式，必选项，此处的值固定为"authorization_code"。
• code：表示上一步获得的授权码，必选项。
• redirect_uri：表示重定向URI，必选项，且必须与A步骤中的该参数值保持一致。
• client_id：表示应用ID，必选项。
• client_secret：表示应用密钥，必选项。

POST https://account-web.suuyuu.cn/oauth/token HTTP/1.1
Host: account-web.suuyuu.cn
Content-Type: application/x-www-form-urlencoded

grant_type=authorization_code&code=1MlxrvXuD7TfH-s4dLzcw9ymO0SKDbf5xAlh3ZEHlMo&redirect_uri=https%3A%2F%2Fwww.baidu.com&client_id=10000002&client_secret=14p9ao1gxu4q3sp8ogk8bq4gkct59t9w

{
    "access_token":"eyJhbGciOiJSUzI1NiIsImtpZCI6IjcwQzQ3OUY1QUIyQTFERjM2QzE0MkNEQjQ3NjQ1QkEwMzQ1MTg1NUEiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJjTVI1OWFzcUhmTnNGQ3piUjJSYm9EUlJoVm8ifQ.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.ElnHr5Niknq7kzGL8iv1TH0F6NQ21yPrswzSTIZuvetUxztYgQpD-RfgBW2HL6b_rRyQxFjE23gU4lBIEayM8k3M9_sUzZq8E_dFT8LwpsU76-CxepxHft4hn1YG0a5C6QRyjFQoSFVUZXIp663Es7vwRQ6PgsfkHZKXxAqXL-obHj_QLbv6OeciTIRGwYrL9-1_SDQ4esFR2n8LkGGOug55j9QuQEKMCufQLJ-nB3y7A2-0mnNoiuF2BBYSPLamcvMcLe8LbhCITLrHkcUSc6tsSdnEeisS6BMIoiyRq-LR2jJwDD30swTPFd85v6kUBJ3ZnWjeCqsluGGKHrwDLA",
    "expires_in":7200,
    "token_type":"Bearer",
    "scope":"api"
}

密码模式（resource owner password credentials）

密码模式主要用于给可信应用颁发用户令牌，此类应用有个性化的登录页（不依赖单点登录，葫芦藤的登录页面），如app、小程序、h5等。

• grant_type：表示授权类型，此处的值固定为"password"，必选项。
• client_id：表示客户端的ID，必选项。
• client_secret：表示客户端密钥，必选项。
• username：用户名，必选项。
• password：密码，必选项。（基于密码原文的rsa加密串）

POST https://account-web.suuyuu.cn/oauth/token HTTP/1.1
Host: account-web.suuyuu.cn
Content-Type: application/x-www-form-urlencoded

grant_type=password&client_id=10000001&client_secret=14p9ao1gxu4q3sp8ogk8bq4gkct59t9w&username=18627131390&password=0200f6389afbcbc624811785c9fbbf5c1b6d7b53b1315a1a43021c0733323fab7625bb9e6594cd30758fa700798421bc189dc223bf696d2438530ffab337809b96bb47ee38f3416bf4b57222050d5f4ad66ee052598ea62ff5ec6f991729956cb692f6f48b758564a46aeff86208581cad9063d3ccd71b551fa4b4b4b983fc1a

{
    "access_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6IjcwQzQ3OUY1QUIyQTFERjM2QzE0MkNEQjQ3NjQ1QkEwMzQ1MTg1NUEiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJjTVI1OWFzcUhmTnNGQ3piUjJSYm9EUlJoVm8ifQ.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.d3qvhX6KSdm5EgWpUzbjJX2bB1OiUo-285nZ1qsGKpqTQJUH1VHQoJogB0NI-uVYdgIV-y3CMBhFY_fDYQJto43zDf0gDvYxa2eWnX5MWL7Augigi59Icp0YvNDCGd2iT5ztAWpxk1Jww815TtCFtFFGiQfQC75bKLrTW9QvdXr8t4VHcFKGmz92m8g3WL-0eWqAyvk0YuSBvxOd8P8zoocEiiOgVKTSylphSIQxuC8B4MFNf2DoFWDQjNZmDCs7PLh7sniMmLdfilo7T7gAlq9qjUrmQmav4wbDMT8WZqa01WY-LsWq6mZUnbCytgSu7Xrr90b6LAEGn-hxdQ5VHg",
    "expires_in": 7200,
    "token_type": "Bearer",
    "scope": "api get_user_info"
}

自定义授权模式（短信、第三方）（extension grant）

客户端通过用户手机号短信验证码或第三方用户（QQ、WeChat）的用户唯一标识（OpenId）向认证服务器索要用户令牌。

以短信验证码方式为例，我们定义的流程如下：

用户向客户端提供自己的手机号和短信验证码。客户端使用这些信息，向认证服务器索要授权。 步骤如下：

（A）用户向客户端提供手机号和短信验证码。
（B）客户端将手机号和短信码发给认证服务器，向后者请求令牌。
（C）认证服务器确认无误后，向客户端提供用户令牌。

B步骤中，客户端发出的HTTP请求，包含以下参数：

• grant_type：表示授权类型，此处的值固定为"sms"，必选项。
• client_id：表示客户端的ID，必选项。
• client_secret：表示客户端的密钥，必选项。
• phone：表示手机号，必选项。
• code：表示短信验证码，必选项。

下面是一个请求示例。

POST https://account-web.suuyuu.cn/oauth/token HTTP/1.1
Host: account-web.suuyuu.cn
Content-Type: application/x-www-form-urlencoded

grant_type=sms&phone=18627131390&code=123456&client_id=10000001&client_secret=14p9ao1gxu4q3sp8ogk8bq4gkct59t9w

{
    "access_token": "eyJhbGciOiJSUzI1NiIsImtpZCI6Ijk5QUEwQzEyMzYwOTc5NzJGMjk3ODk1NjI3NjFEMzhBQUUzMDE5MTgiLCJ0eXAiOiJKV1QiLCJ4NXQiOiJtYW9NRWpZSmVYTHlsNGxXSjJIVGlxNHdHUmcifQ.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_neeVmeWcsOWdgCIsInNjb3BlIjpbImFwaSIsImdldF91c2VyX2luZm8iXSwiYW1yIjpbInBhc3N3b3JkIiwibWZhIl19.ZQklMJMXObc3vL-gMOWnWIS56ck5_XbDfXjw9Vm6BeYjG4dyz05JTN_YHgU-EIJoM04nmFyjNgGYtqL-28-3MQeHfWhvQf_5dyY1w-DBBCKo1EMEm_ujKTDB1QQTN1XmVTgW7bBkEiv4NK5v3uYqh_s7pv8Csusm4oWZThWPlKLtxWVDtawFzvz4Un-2WATytsLNfluutiLVnpN7INhkdglansTTOCUOdCOLBEEbDzTuLyCnhm00xYtg5GrMAkDohqXLKYD2jSFzIyYTA_oryTFXcJpkGYwIRqRX7bXvAlMR5yE_CTtNWpSnaLJ2GtFv_QFe-YItCtSO-bBd6XQBRA",
    "expires_in": 7200,
    "token_type": "Bearer",
    "scope": "api get_user_info"
}

第三方授权登录的编写与使用

在葫芦藤项目中我们提供了钉钉、微信的OAuth组件，并实现了功能，演示地址在 https://account.suuyuu.cn，下面我们以微信为例简单介绍下如何编写组件及使用。

首先咱们阅读一下网站应用微信登录开发指南，了解一下接入流程。要使用微信登录，先得在微信·开放平台注册成为开发者，并进行资质认证。

微信开放平台帐号的开发者资质认证提供更安全、更严格的真实性认证、也能够更好的保护企业及用户的合法权益
开发者资质认证通过后，微信开放平台帐号下的应用，将获得微信登录、智能接口、第三方平台开发等高级能力
审核费用：中国大陆地区：300元，非中国大陆地区：99美元

然后在管理中心创建网站应用

对照微信开发指南将需要用到的地址定义到WeChatDefaults.cs中

public static class WeChatDefaults
{
    public const string AuthenticationScheme = "wechat";

    public static readonly string DisplayName = "wechat";
    //第一步：请求CODE
    public static readonly string AuthorizationEndpoint = "https://open.weixin.qq.com/connect/qrconnect";
    //第二步：通过code获取access_token
    public static readonly string TokenEndpoint = "https://api.weixin.qq.com/sns/oauth2/access_token";
    //第三步：获取用户个人信息
    public static readonly string UserInformationEndpoint = "https://api.weixin.qq.com/sns/userinfo";
}

此处唯一要注意的地方，ClaimActions集合的参数来自微信返回的字段

public class WeChatOptions : OAuthOptions
{
    /// <summary>
    /// Initializes a new <see cref="WeChatOptions"/>.
    /// </summary>
    public WeChatOptions()
    {
        CallbackPath = new PathString("/signin-wechat");
        AuthorizationEndpoint = WeChatDefaults.AuthorizationEndpoint;
        TokenEndpoint = WeChatDefaults.TokenEndpoint;
        UserInformationEndpoint = WeChatDefaults.UserInformationEndpoint;
        Scope.Add("snsapi_login");

        ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "openid");
        ClaimActions.MapJsonKey(ClaimTypes.Name, "nickname");
    }

    /// <summary>
    /// access_type. Set to 'offline' to request a refresh token.
    /// </summary>
    public string AccessType { get; set; }
}

public static class WeChatExtensions
{
    public static AuthenticationBuilder AddWeChat(this AuthenticationBuilder builder)
        => builder.AddWeChat(WeChatDefaults.AuthenticationScheme, _ => { });

    public static AuthenticationBuilder AddWeChat(this AuthenticationBuilder builder, Action<WeChatOptions> configureOptions)
        => builder.AddWeChat(WeChatDefaults.AuthenticationScheme, configureOptions);

    public static AuthenticationBuilder AddWeChat(this AuthenticationBuilder builder, string authenticationScheme, Action<WeChatOptions> configureOptions)
        => builder.AddWeChat(authenticationScheme, WeChatDefaults.DisplayName, configureOptions);

    public static AuthenticationBuilder AddWeChat(this AuthenticationBuilder builder, string authenticationScheme, string displayName, Action<WeChatOptions> configureOptions)
        => builder.AddOAuth<WeChatOptions, WeChatHandler>(authenticationScheme, displayName, configureOptions);
}

新增一个类WeChatHandler，继承自OAuthHandler

BuildChallengeUrl（构造客户端申请认证的URI）

protected override string BuildChallengeUrl(AuthenticationProperties properties, string redirectUri)
{
    var state = Options.StateDataFormat.Protect(properties);
    var baseUri = $"{Request.Scheme}{Uri.SchemeDelimiter}{Request.Host}{Request.PathBase}";
    var currentUri = $"{baseUri}{Request.Path}{Request.QueryString}";

    if (string.IsNullOrEmpty(properties.RedirectUri))
    {
        properties.RedirectUri = currentUri;
    }

    var queryStrings = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
    {
        {"response_type", "code"},
        {"appid", Uri.EscapeDataString(Options.ClientId)},
        {"redirect_uri", redirectUri},
        {"state", Uri.EscapeDataString(state)}
    };

    var scope = string.Join(",", Options.Scope);
    queryStrings.Add("scope", Uri.EscapeDataString(scope));

    var authorizationEndpoint = QueryHelpers.AddQueryString(Options.AuthorizationEndpoint, queryStrings);
    return authorizationEndpoint;
}

HandleRemoteAuthenticateAsync（向认证服务器申请令牌获取用户信息并创建票据）

protected override async Task<HandleRequestResult> HandleRemoteAuthenticateAsync()
{

    var state = Request.Query["state"];
    var properties = Options.StateDataFormat.Unprotect(state);

    if (properties == null)
        return HandleRequestResult.Fail("The oauth state was missing or invalid.");
    if (!ValidateCorrelationId(properties))
        return HandleRequestResult.Fail("Correlation failed.", properties);

    var code = Request.Query["code"];
    if (StringValues.IsNullOrEmpty(code))
        return HandleRequestResult.Fail("Code was not found.", properties);

    var redirectUri = !string.IsNullOrEmpty(Options.CallbackPath) ?
        Options.CallbackPath.Value : BuildRedirectUri(Options.CallbackPath);

    var context = new OAuthCodeExchangeContext(properties, code, redirectUri);

    var tokens = await ExchangeCodeAsync(context);

    if (tokens.Error != null)
        return HandleRequestResult.Fail(tokens.Error, properties);
    if (string.IsNullOrEmpty(tokens.AccessToken))
        return HandleRequestResult.Fail("Failed to retrieve access token.", properties);
    var identity = new ClaimsIdentity(ClaimsIssuer);

    if (Options.SaveTokens)
    {
        var authenticationTokenList = new List<AuthenticationToken>
        {
            new AuthenticationToken
            {
                Name = "access_token",
                Value = tokens.AccessToken
            }
        };
        if (!string.IsNullOrEmpty(tokens.RefreshToken))
        {
            authenticationTokenList.Add(new AuthenticationToken
            {
                Name = "refresh_token",
                Value = tokens.RefreshToken
            });
        }

        if (!string.IsNullOrEmpty(tokens.TokenType))
        {
            authenticationTokenList.Add(new AuthenticationToken
            {
                Name = "token_type",
                Value = tokens.TokenType
            });
        }

        if (!string.IsNullOrEmpty(tokens.ExpiresIn) && int.TryParse(tokens.ExpiresIn, NumberStyles.Integer, CultureInfo.InvariantCulture, out var result))
        {
            var dateTimeOffset = Clock.UtcNow + TimeSpan.FromSeconds(result);
            authenticationTokenList.Add(new AuthenticationToken()
            {
                Name = "expires_at",
                Value = dateTimeOffset.ToString("o", CultureInfo.InvariantCulture)
            });
        }
        properties.StoreTokens(authenticationTokenList);
    }

    var ticket = await CreateTicketAsync(identity, properties, tokens);
    return ticket == null ? HandleRequestResult.Fail("Failed to retrieve user information from remote server.", properties) : HandleRequestResult.Success(ticket);
}

此步骤中包含两个子步骤

ExchangeCodeAsync（交换授权码Code）

protected override async Task<OAuthTokenResponse> ExchangeCodeAsync(OAuthCodeExchangeContext context)
{

    var tokenRequestParameters = new List<KeyValuePair<string, string>>
    {
        new KeyValuePair<string, string>("appid", Options.ClientId),
        new KeyValuePair<string, string>("secret", Options.ClientSecret),
        new KeyValuePair<string, string>("code", context.Code),
        new KeyValuePair<string, string>("grant_type", "authorization_code"),
    };

    var urlEncodedContent = new FormUrlEncodedContent(tokenRequestParameters);

    var response =
        await Backchannel.PostAsync(Options.TokenEndpoint, urlEncodedContent, Context.RequestAborted);

    return response.IsSuccessStatusCode ? OAuthTokenResponse.Success(JsonDocument.Parse(await response.Content.ReadAsStringAsync())) : OAuthTokenResponse.Failed(new Exception("OAuth token failure"));
}

CreateTicketAsync（创建票据）

protected override async Task<AuthenticationTicket> CreateTicketAsync(ClaimsIdentity identity,AuthenticationProperties properties,OAuthTokenResponse tokens)
{
    var openId = tokens.Response.RootElement.GetString("openid");

    var parameters = new Dictionary<string, string>
    {
        {  "openid", openId},
        {  "access_token", tokens.AccessToken }
    };
    var userInfoEndpoint = QueryHelpers.AddQueryString(Options.UserInformationEndpoint, parameters);
    var response = await Backchannel.GetAsync(userInfoEndpoint, Context.RequestAborted);

    if (!response.IsSuccessStatusCode)
    {
        throw new HttpRequestException($"An error occurred when retrieving WeChat user information ({response.StatusCode}). Please check if the authentication information is correct.");
    }

    using (var payload = JsonDocument.Parse(await response.Content.ReadAsStringAsync()))
    {
        var context = new OAuthCreatingTicketContext(new ClaimsPrincipal(identity), properties, Context, Scheme,
            Options, Backchannel, tokens, payload.RootElement);

        context.RunClaimActions();
        await Events.CreatingTicket(context);

        context.Properties.ExpiresUtc = DateTimeOffset.Now.AddMinutes(15);
        return new AuthenticationTicket(context.Principal, context.Properties, Scheme.Name);
    }
}

组件写好了，怎么使用呢？在Fulu.Passport.Web项目的Startup.cs文件中添加代码如下：

public void ConfigureServices(IServiceCollection services)
{
    ......省略部分代码......
    
    services.AddAuthentication().AddWeChat(o =>
    {
        o.SignInScheme = IdentityServerConstants.ExternalCookieAuthenticationScheme;
        o.ClientId = Configuration["ExternalWeChat:AppId"];
        o.ClientSecret = Configuration["ExternalWeChat:Secret"];
    })
}

接着，在UserController.cs中添加如下代码：

/// <summary>
/// 外部账号登录
/// </summary>
/// <param name="model"></param>
/// <returns></returns>
[HttpGet, AllowAnonymous]
public IActionResult ExternalLogin([FromQuery] ExternalLoginModel model)
{
    var authenticationProperties = new AuthenticationProperties()
    {
        RedirectUri = Url.Action(nameof(ExternalLoginCallback)),
        Items =
        {
            { "returnUrl", model.ReturnUrl },
            { "scheme", model.Provider },
        }
    };

    return Challenge(authenticationProperties, model.Provider);
}

/// <summary>
/// 外部登录回调
/// </summary>
/// <returns></returns>
[HttpGet]
[AllowAnonymous]
public async Task<IActionResult> ExternalLoginCallback()
{
    //获取idsrv.external Cookie 对象
    var result = await HttpContext.AuthenticateAsync(IdentityServerConstants.ExternalCookieAuthenticationScheme);

    var returnUrl = result.Properties.Items["returnUrl"];

    if (result.Succeeded == false)
    {
        return await RedirectErrorResult("error", "External authentication error", returnUrl);
    }
    ......省略部分代码......

    //删除 idsrv.external Cookie
    await HttpContext.SignOutAsync(IdentityServerConstants.ExternalCookieAuthenticationScheme);
    //写入 .AspNetCore.Cookies
    await SignIn(userEntity, UserLoginModel.External);

    return Redirect(returnUrl);
}

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