Bug#35054579 Issue in Oracle MySQL Client using utf16 charset

Description:
If we try to connect the server with mysql client using
--default-character-set=utf1 using a authentication plugin,
the client connection is failing with below error
ERROR 2059 (HY000): Authentication plugin '../../mysql_native_password' cannot be loaded:
'../../mysql_native_password.so': cannot open shared object file: No such file or directory
instead of
ERROR 2059 (HY000): Authentication plugin '../../mysql_native_password' cannot be loaded:
No paths allowed for shared library

Analysis:
As per mysql documentation utf16, utf32, ucs2 and utf16le are
Impermissible Client Character Sets, so when the client tries to
connect the server with these charsets, the client has to reject the
connections.

Fix:
While parsing the mysq client options, detecting the
Impermissible Client Character Sets and rejecting the connection.

Change-Id: Ib0d6624c792214b7b44fbb7040646f04081fb3e0

Author: V S Murthy Sidagam

client/mysql.cc

@@ -4731,7 +4731,7 @@ static bool init_connection_options(MYSQL *mysql) {
     mysql_options(mysql, MYSQL_INIT_COMMAND, init_command);
   }
 
-  mysql_set_character_set(mysql, default_charset);
+  if (mysql_set_character_set(mysql, default_charset)) return true;
 
   if (opt_plugin_dir && *opt_plugin_dir)
     mysql_options(mysql, MYSQL_PLUGIN_DIR, opt_plugin_dir);

include/errmsg.h

@@ -132,7 +132,8 @@ extern const char *client_errors[]; /* Error messages */
 #define CR_MANDATORY_TRACKER_NOT_FOUND 2071
 #define CR_INVALID_FACTOR_NO 2072
 #define CR_CANT_GET_SESSION_DATA 2073
-#define CR_ERROR_LAST /*Copy last error nr:*/ 2073
+#define CR_INVALID_CLIENT_CHARSET 2074
+#define CR_ERROR_LAST /*Copy last error nr:*/ 2074
 /* Add error numbers before CR_ERROR_LAST and change it accordingly. */
 
 /* Visual Studio requires '__inline' for C code */

include/mysql.h.pp

@@ -364,7 +364,7 @@
 void finish_client_errs(void);
 extern const char *client_errors[];
 static inline const char *ER_CLIENT(int client_errno) {
-  if (client_errno >= 2000 && client_errno <= 2073)
+  if (client_errno >= 2000 && client_errno <= 2074)
     return client_errors[client_errno - 2000];
   return client_errors[2000 - 2000];
 }

libmysql/errmsg.cc

@@ -119,6 +119,9 @@ const char *client_errors[] = {
     "Invalid first argument for MYSQL_OPT_USER_PASSWORD option. Valid value "
     "should be between 1 and 3 inclusive.",
     "Can't get session data: %s",
+    "'%-.32s' character set is having more than 1 byte minimum character "
+    "length, which cannot be used as a client character set. Please use any "
+    "of the single byte minimum ones, e.g. utf8mb4, latin1 etc.",
     ""};
 
 static const char *get_client_errmsg(int nr) {

sql-common/client.cc

@@ -9211,6 +9211,17 @@ int STDCALL mysql_set_character_set(MYSQL *mysql, const char *cs_name) {
     cs_name = mysql->options.charset_name;
   }
 
+#ifndef MYSQL_SERVER
+  if (mysql->charset != nullptr) {
+    if (!is_supported_parser_charset(mysql->charset)) {
+      set_mysql_extended_error(mysql, CR_INVALID_CLIENT_CHARSET,
+                               unknown_sqlstate,
+                               ER_CLIENT(CR_INVALID_CLIENT_CHARSET), cs_name);
+      return 1;
+    }
+  }
+#endif
+
   if (strlen(cs_name) < MY_CS_NAME_SIZE &&
       (cs = get_charset_by_csname(cs_name, MY_CS_PRIMARY, MYF(0)))) {
     char buff[MY_CS_NAME_SIZE + 10];