利用MYSQL的函数实现用户登录功能，进出都是JSON(第一版)

以HMAC密钥形式发放密钥令牌

功能如下

1：记录用户的登录的IP地址、时间

2：实现密码错误次数超限后锁定，并提示何时解锁

CREATE DEFINER=`root`@`%` FUNCTION `uc_session_login`(
    `reqjson` JSON,
    `srvjson` JSON
)
RETURNS json
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT 'JSON用户登录'
BEGIN
    #SELECT `uc_session_login`('{"email":"xxscn@qq.com","pwdmd5":"md5加密后的密码"}','{"ipaddress":"用户登录的IP地址"}')json
    DECLARE retjson JSON DEFAULT'{"errno":0}';
    #密钥表
    DECLARE _keyid INT(10)UNSIGNED;
    DECLARE _secretkey CHAR(32);
    #登录表
    DECLARE _uid INT(10)UNSIGNED;
    DECLARE _username VARCHAR(50);
    DECLARE _password CHAR(32);
    DECLARE _salt CHAR(6);
    #地址记录表
    DECLARE _failedlogins INT(10)UNSIGNED;
    DECLARE _beforedel TIMESTAMP;
    #与字段无关的输入
    DECLARE failedlogins_max INT(10)UNSIGNED DEFAULT 3;#密码错误次数上限
    DECLARE failedlogins_timeout INT(10)UNSIGNED DEFAULT 20;#时间范围内清零计数
    DECLARE failedlogins_unlocktime INT(10)UNSIGNED DEFAULT 10;#密码错误次数超限后锁定时间
    #DECLARE srvjson JSON DEFAULT IFNULL(CAST(@srvjson AS CHAR),'{}');#IFNULL(@srvjson,'{}')#已由会话变量改为函数的参数
    DECLARE secretkey2 VARCHAR(32)DEFAULT IFNULL(srvjson->>'$.secretkey2','');#二级密钥
    DECLARE useripaddress VARCHAR(39)DEFAULT srvjson->>'$.ipaddress';#用户IP地址
    DECLARE req_email VARCHAR(50)DEFAULT reqjson->>'$.email';
    DECLARE req_pwdmd5 CHAR(32)DEFAULT reqjson->>'$.pwdmd5';
    #与字段无关的输出
    DECLARE json JSON DEFAULT'{}';
    #首先判断IP地址是否已被禁止尝试密码
    DELETE FROM uc_session_ipaddress WHERE beforedel<CURRENT_TIMESTAMP();#删除较早的IP
    SET _failedlogins=0;
    SELECT failedlogins,beforedel INTO _failedlogins,_beforedel FROM uc_session_ipaddress WHERE ipaddress=useripaddress;
    IF _failedlogins>=failedlogins_max THEN
        SET retjson=JSON_SET(retjson,'$.errno',-11);
        SET retjson=JSON_SET(retjson,'$.message',CONCAT('由于密码错误次数过多，已被锁定。解锁时间：',_beforedel));
        RETURN retjson;
    END IF;
    SELECT uid,username,`password`,salt INTO _uid,_username,_password,_salt FROM uc_members WHERE email=req_email;
    IF ISNULL(_uid) THEN RETURN '{"error":-1,"message":"您输入的E-Mail尚未注册"}';END IF;
    IF MD5(CONCAT(req_pwdmd5,_salt))<>_password THEN
        INSERT INTO uc_session_log(uid,ipaddress,errno,error)VALUES(_uid,useripaddress,-2,'登录密码错误');
        SET @curfailed=_failedlogins+1;
        IF _failedlogins=0 THEN
            #第一次密码错误
            INSERT INTO uc_session_ipaddress(ipaddress,failedlogins,beforedel)VALUES(useripaddress,1,TIMESTAMPADD(SECOND,failedlogins_timeout,CURRENT_TIMESTAMP()));
        ELSE
            UPDATE uc_session_ipaddress SET failedlogins=@curfailed,beforedel=TIMESTAMPADD(SECOND,failedlogins_unlocktime,CURRENT_TIMESTAMP()) WHERE ipaddress=useripaddress;
        END IF;
        IF @curfailed>=failedlogins_max THEN
            SET retjson=JSON_SET(retjson,'$.errno',-3);
            SET retjson=JSON_SET(retjson,'$.message',CONCAT('由于密码错误次数已达',failedlogins_max,'次，现已被锁定',failedlogins_unlocktime,'秒'));
            RETURN retjson;
        END IF;
        SET retjson=JSON_SET(retjson,'$.errno',-2);
        SET retjson=JSON_SET(retjson,'$.message',CONCAT('您已输错',@curfailed,'次密码，如再错',failedlogins_max-@curfailed,'次将被锁定',failedlogins_unlocktime,'秒'));
        RETURN retjson;
    END IF;
    #登录校验已通过，开始取得secretkey并出hmac
    SELECT id,secretkey INTO _keyid,_secretkey FROM uc_session_key WHERE started<CURRENT_TIMESTAMP() AND expired>CURRENT_TIMESTAMP() ORDER BY expired DESC LIMIT 1;
    IF ISNULL(_keyid) OR ISNULL(_secretkey) THEN RETURN '{"error":-3,"message":"secretkey获取失败"}';END IF;
    SET json=JSON_SET(json,'$.logintime',UNIX_TIMESTAMP(CURRENT_TIMESTAMP(6)));
    SET json=JSON_SET(json,'$.loginip',useripaddress);
    SET json=JSON_SET(json,'$.uid',_uid);
    SET json=JSON_SET(json,'$.email',req_email);
    SET json=JSON_SET(json,'$.username',_username);
    SET json=JSON_SET(json,'$.password',_password);
    SET json=JSON_SET(json,'$.salt',_salt);
    DELETE FROM uc_session_ipaddress WHERE ipaddress=useripaddress;#删除较早的IP
    INSERT INTO uc_session_log(uid,ipaddress,errno,error)VALUES(_uid,useripaddress,0,'登录成功');
    SET retjson=JSON_SET(retjson,'$.userjson',CAST(json AS CHAR));
    SET retjson=JSON_SET(retjson,'$.keyid',_keyid);
    SET retjson=JSON_SET(retjson,'$.hmacsha1',uc_session_hmacsha1(CONCAT(_secretkey,secretkey2),retjson->>'$.userjson'));
    SET retjson=JSON_SET(retjson,'$.errno',0);
    SET retjson=JSON_SET(retjson,'$.message','登录成功');
    RETURN retjson;
END