MXS-1319: Set SQL_MODE for all internal connections

When an internal connection is created, the SQL_MODE of the connection
should be set to a known default. The empty SQL_MODE allows consistent
functionality for all backend server versions.

maxscale-system-test/CMakeLists.txt

@@ -476,6 +476,10 @@ add_test_executable(mxs1045.cpp mxs1045 mxs1045 LABELS maxscale REPL_BACKEND)
 # https://jira.mariadb.org/browse/MXS-1123
 add_test_executable(mxs1123.cpp mxs1123 mxs1123 LABELS maxscale REPL_BACKEND)
 
+# MXS-1319: Maxscale selecting extra whitespace while loading users
+# https://jira.mariadb.org/browse/MXS-1319
+add_test_executable(mxs1319.cpp mxs1319 replication LABELS MySQLAuth REPL_BACKEND)
+
 # 'namedserverfilter' test
 add_test_executable(namedserverfilter.cpp namedserverfilter namedserverfilter LABELS namedserverfilter LIGHT REPL_BACKEND)
 

maxscale-system-test/mxs1319.cpp

@@ -0,0 +1,23 @@
+/**
+ * Check that SQL_MODE='PAD_CHAR_TO_FULL_LENGTH' doesn't break authentication
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char *argv[])
+{
+    TestConnections test(argc, argv);
+
+    test.tprintf("Changing SQL_MODE to PAD_CHAR_TO_FULL_LENGTH and restarting MaxScale");
+    test.repl->connect();
+    test.repl->execute_query_all_nodes("SET GLOBAL SQL_MODE='PAD_CHAR_TO_FULL_LENGTH'");
+    test.restart_maxscale();
+
+    test.tprintf("Connecting to MaxScale and executing a query");
+    test.connect_maxscale();
+    test.try_query(test.conn_rwsplit, "SELECT 1");
+    test.close_maxscale_connections();
+
+    test.repl->execute_query_all_nodes("SET GLOBAL SQL_MODE=DEFAULT");
+    return test.global_result;
+}

server/core/mysql_utils.c

@@ -174,6 +174,11 @@ MYSQL *mxs_mysql_real_connect(MYSQL *con, SERVER *server, const char *user, cons
         MY_CHARSET_INFO cs_info;
         mysql_get_character_set_info(mysql, &cs_info);
         server->charset = cs_info.number;
+
+        if (mysql_query(mysql, "SET SQL_MODE=''"))
+        {
+            MXS_ERROR("Failed to change SQL_MODE: %s", mysql_error(mysql));
+        }
     }
 
     return mysql;