Problems occur when parsing sql_mode

[cahlchang]

I found the failure in the parser with following SQL.

issue

SET @@SESSION.sql_mode = CONCAT(CONCAT(@@sql_mode, ',STRICT_ALL_TABLES'), ',NO_AUTO_VALUE_ON_ZERO');

This SQL statement is often used in combination of RoR 5 and MySQL 5.
In the current parser, I assumed only one CONCAT function, it seemed that the interpretation of the regular expression was wrong.
see
https://github.com/sysown/proxysql/blob/v2.0.2/lib/set_parser.cpp#L38
The following error sentence can be seen.

2019-02-14 10:47:29 MySQL_Session.cpp:1610:handler_again___status_SETTING_SQL_MODE(): [WARNING] Error while setting SQL_MODE: 1231, Variable 'sql_mode' can't be set to the value of 'CONCAT'

I resolved this problem. I’ll send a PR, review it please.

• A clear description of your issue

version

# ~/proxysql.org --version
ProxySQL version 2.0.1-4-gac2e710, codename Truls

CentOS Linux 7.4

• The version of OS and ProxySQL

Reproduction

A driver that pools connection such as RoR 5, when nesting two or more CONCAT functions.

• Every step to reproduce the issue

error log

Repeat it.

2019-02-14 10:47:29 MySQL_Session.cpp:1610:handler_again___status_SETTING_SQL_MODE(): [WARNING] Error while setting SQL_MODE: 1231, Variable 'sql_mode' can't be set to the value of 'CONCAT'

• The error log

core dump

Although accurate reproduction has not been obtained, the next core dump was found.

(gdb) backtrace
#0  0x00000000004e2de7 in MySQL_Protocol::process_pkt_handshake_response (this=0x7f17d70a1ea0, pkt=0x7f17d85fa132 "caching_sha2_password", len=<optimized out>) at MySQL_Protocol.cpp:1510
#1  0x00000000004ce13b in MySQL_Session::handler___status_CONNECTING_CLIENT___STATE_SERVER_HANDSHAKE (this=0x7f17d70c8200, pkt=0x7f17d7bfd840, wrong_pass=0x7f17d7bfd82f)
    at MySQL_Session.cpp:3526
#2  0x00000000004db31e in MySQL_Session::handler (this=this@entry=0x7f17d70c8200) at MySQL_Session.cpp:2177
#3  0x00000000004bfc9c in MySQL_Thread::process_all_sessions (this=this@entry=0x7f17d709dc00) at MySQL_Thread.cpp:3578
#4  0x00000000004ca1e6 in MySQL_Thread::run (this=this@entry=0x7f17d709dc00) at MySQL_Thread.cpp:3337
#5  0x000000000048b8fc in mysql_worker_thread_func (arg=0x7f17d98d7430) at main.cpp:627
#6  0x00007f17dafdae25 in start_thread () from /lib64/libpthread.so.0
#7  0x00007f17d9ec634d in clone () from /lib64/libc.so.6

• If it is a crashing bug, please check here:

[gondaz]

Confirm the aforementioned behavior. Hope, it will be fixed in the upcoming update.

[renecannao]

Fixed in ProxySQL 2.0.4.
Thank you very much for the report.

[cahlchang]

Thanks to improve!