# 目录
- [IdentityServer4源码解析_1_项目结构](https://www.cnblogs.com/holdengong/p/12578558.html)
- [IdentityServer4源码解析_2_元数据接口](https://www.cnblogs.com/holdengong/p/12580738.html)
- [IdentityServer4源码解析_3_认证接口](https://www.cnblogs.com/holdengong/p/12585466.html)
- [IdentityServer4源码解析_4_令牌发放接口](https://www.cnblogs.com/holdengong/p/12589436.html)
- [IdentityServer4源码解析_5_查询用户信息接口](https://www.cnblogs.com/holdengong/p/12594007.html)
- [IdentityServer4源码解析_6_结束会话接口]
- [IdentityServer4源码解析_7_查询令牌信息接口]
- [IdentityServer4源码解析_8_撤销令牌接口]
# 协议简析
UserInfo接口是OAuth2.0中规定的需要认证访问的接口，可以返回认证用户的声明信息。请求UserInfo接口需要使用通行令牌。响应报文通常是json数据格式，包含了一组claim键值对集合。与UserInfo接口通讯必须使用https。
根据RFC2616协议，UserInfo必须支持GET和POST方法。
UserInfo接口必须接受Bearer令牌。
UserInfo接口应该支持javascript客户端跨域访问，可以使用CORS协议或者其他方案。
## UserInfo请求
推荐使用GET方法，使用Authorization头承载Bearer令牌来请求UserInfo接口。
```http
GET /userinfo HTTP/1.1
Host: server.example.com
Authorization: Bearer SlAV32hkKG
```
## 成功响应
如果某个claim为空或者null，不返回该键。
必须返回sub（subject）声明。
必须校验UserInfo返回的sub与id_token中的sub是否一致
content-type必须是application/json，必须使用utf-8编码
如果加密位jwt返回，content-type必须位application/jwt
```http
HTTP/1.1 200 OK
Content-Type: application/json
{
"sub": "248289761001",
"name": "Jane Doe",
"given_name": "Jane",
"family_name": "Doe",
"preferred_username": "j.doe",
"email": "janedoe@example.com",
"picture": "http://example.com/janedoe/me.jpg"
}
```
## 失败响应
```http
HTTP/1.1 401 Unauthorized
WWW-Authenticate: error="invalid_token",
error_description="The Access Token expired"
```
## 响应校验
客户端必须校验如下内容
- 校验认证服务身份(https)
- 如果客户端注册时设置了userinfo_encrypted_response_alg ，收到响应时用对应算法解密
- 如果响应有签名，客户端需要验签
# 源码解析
## 校验通行令牌
- 首先会尝试从`Authorizaton`头中获取`Bearer Token`的值，找到的话则返回
- 如果content-type为表单类型，尝试从表单中获取`access_token`参数值
- 两处都没有获取到`Beaer Token`的话则返回校验失败结果
```csharp
public async Task ValidateAsync(HttpContext context)
{
var result = ValidateAuthorizationHeader(context);
if (result.TokenFound)
{
_logger.LogDebug("Bearer token found in header");
return result;
}
if (context.Request.HasFormContentType)
{
result = await ValidatePostBodyAsync(context);
if (result.TokenFound)
{
_logger.LogDebug("Bearer token found in body");
return result;
}
}
_logger.LogDebug("Bearer token not found");
return new BearerTokenUsageValidationResult();
}
```
## 校验请求参数
由`IUserInfoRequestValidator`的默认实现`UserInfoRequestValidator`对入参进行校验。
1. `accessToken`，必须包括`openid`声明的权限
2. 必须有`sub`声明,`sub`是`subject`的缩写，代表用户唯一标识
3. 收集`accessToken`所有`claim`，移除以下与用户信息无关的`claim`。
at_hash,aud,azp,c_hash,client_id,exp,iat,iss,jti,nonce,nbf,reference_token_id,sid,scope
用筛选后的`claim`创建名称为`UserInfo`的`Principal`
4. 调用`IProfileService`的`IsAcriveAsync`方法判断用户是否启用，不是启动状态的话返回`invalid_token`错误
5. 返回校验成功结果对象，包括步骤3构建的`Principal`
```csharp
public async Task ValidateRequestAsync(string accessToken)
{
// the access token needs to be valid and have at least the openid scope
var tokenResult = await _tokenValidator.ValidateAccessTokenAsync(
accessToken,
IdentityServerConstants.StandardScopes.OpenId);
if (tokenResult.IsError)
{
return new UserInfoRequestValidationResult
{
IsError = true,
Error = tokenResult.Error
};
}
// the token must have a one sub claim
var subClaim = tokenResult.Claims.SingleOrDefault(c => c.Type == JwtClaimTypes.Subject);
if (subClaim == null)
{
_logger.LogError("Token contains no sub claim");
return new UserInfoRequestValidationResult
{
IsError = true,
Error = OidcConstants.ProtectedResourceErrors.InvalidToken
};
}
// create subject from incoming access token
var claims = tokenResult.Claims.Where(x => !Constants.Filters.ProtocolClaimsFilter.Contains(x.Type));
var subject = Principal.Create("UserInfo", claims.ToArray());
// make sure user is still active
var isActiveContext = new IsActiveContext(subject, tokenResult.Client, IdentityServerConstants.ProfileIsActiveCallers.UserInfoRequestValidation);
await _profile.IsActiveAsync(isActiveContext);
if (isActiveContext.IsActive == false)
{
_logger.LogError("User is not active: {sub}", subject.GetSubjectId());
return new UserInfoRequestValidationResult
{
IsError = true,
Error = OidcConstants.ProtectedResourceErrors.InvalidToken
};
}
return new UserInfoRequestValidationResult
{
IsError = false,
TokenValidationResult = tokenResult,
Subject = subject
};
}
```
## 生成响应报文
调用`IUserInfoResponseGenerator`接口的默认实现`UserInfoResponseGenerator`的`ProcessAsync`方法生成响应报文。
1. 从校验结果中获取`scope`声明值，查询`scope`值关联的`IdentityResource`(身份资源)及其关联的所有`claim`。得到的结果就是用户请求的所有`claim`
2. 调用`DefaultProfileService`的`GetProfileDataAsync`方法，返回校验结果`claim`与用户请求`claim`的交集。
3. 如果`claim`集合中没有`sub`，取校验结果中的`sub`值。如果`IProfileService`返回的`sub`声明值与校验结果的`sub`值不一致抛出异常。
4. 返回`claim`集合。
5. 响应头写入`Cache-Control:no-store, no-cache, max-age=0`,`Pragma:no-cache`
6. `claim`集合用json格式写入响应内容
```csharp
public virtual async Task> ProcessAsync(UserInfoRequestValidationResult validationResult)
{
Logger.LogDebug("Creating userinfo response");
// extract scopes and turn into requested claim types
var scopes = validationResult.TokenValidationResult.Claims.Where(c => c.Type == JwtClaimTypes.Scope).Select(c => c.Value);
var requestedClaimTypes = await GetRequestedClaimTypesAsync(scopes);
Logger.LogDebug("Requested claim types: {claimTypes}", requestedClaimTypes.ToSpaceSeparatedString());
// call profile service
var context = new ProfileDataRequestContext(
validationResult.Subject,
validationResult.TokenValidationResult.Client,
IdentityServerConstants.ProfileDataCallers.UserInfoEndpoint,
requestedClaimTypes);
context.RequestedResources = await GetRequestedResourcesAsync(scopes);
await Profile.GetProfileDataAsync(context);
var profileClaims = context.IssuedClaims;
// construct outgoing claims
var outgoingClaims = new List();
if (profileClaims == null)
{
Logger.LogInformation("Profile service returned no claims (null)");
}
else
{
outgoingClaims.AddRange(profileClaims);
Logger.LogInformation("Profile service returned the following claim types: {types}", profileClaims.Select(c => c.Type).ToSpaceSeparatedString());
}
var subClaim = outgoingClaims.SingleOrDefault(x => x.Type == JwtClaimTypes.Subject);
if (subClaim == null)
{
outgoingClaims.Add(new Claim(JwtClaimTypes.Subject, validationResult.Subject.GetSubjectId()));
}
else if (subClaim.Value != validationResult.Subject.GetSubjectId())
{
Logger.LogError("Profile service returned incorrect subject value: {sub}", subClaim);
throw new InvalidOperationException("Profile service returned incorrect subject value");
}
return outgoingClaims.ToClaimsDictionary();
}
```
