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。

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/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/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

public async Task<BearerTokenUsageValidationResult> 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。

accessToken，必须包括openid声明的权限
必须有sub声明,sub是subject的缩写，代表用户唯一标识
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
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
返回校验成功结果对象，包括步骤3构建的Principal


public async Task<UserInfoRequestValidationResult> 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。

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
调用DefaultProfileService的GetProfileDataAsync方法，返回校验结果claim与用户请求claim的交集。
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。
返回claim集合。
响应头写入Cache-Control:no-store, no-cache, max-age=0,Pragma:no-cache
claim集合用json格式写入响应内容

 public virtual async Task<Dictionary<string, object>> 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<Claim>();

    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();
}

秒客网

IdentityServer4源码解析_5_查询用户信息接口

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