Fix for bug #13407 "Remote connecting crashes server" and couple of similar

problems which were introduced during work on WL#2787 "Add view definer/owner
to the view definition (.frm) to check privileges on used tables and stored
routines when using a VIEW."

In some cases it is better to use value from Security_context::host_or_ip
instead of value from Security_context::host since the latter can be NULL
in certain situations (When we can't resolve hostname or we have not done
this yet).


mysql-test/r/skip_name_resolve.result:
  Added test for bug #13407 "Remote connecting crashes server".
mysql-test/t/skip_name_resolve.test:
  Added test for bug #13407 "Remote connecting crashes server".
sql/item_strfunc.cc:
  Item_func_user::val_str():
    It is better to use value from Security_context::host_or_ip instead of
    value from Security_context::host in the result of USER() function since
    the latter can be NULL in certain situations (When we can't resolve hostname
    or we have not done this yet. Reverted back to old code).
sql/mysqld.cc:
  handle_connections_shared_memory():
   THD::host member has moved to the Security_context class.
   New THD::security_ctx member points to active security context.
sql/sql_show.cc:
  mysqld_list_processes():
    It is better to use value from Security_context::host_or_ip instead of
    value from Security_context::host in the processlist since the latter
    can be NULL in certain situations (When we can't resolve hostname or we
    have not done this yet. Reverted back to old code).

mysql-test/r/skip_name_resolve.result

@@ -5,3 +5,10 @@ GRANT USAGE ON *.* TO 'mysqltest_1'@'127.0.0.1/255.255.255.255'
 GRANT ALL PRIVILEGES ON `test`.* TO 'mysqltest_1'@'127.0.0.1/255.255.255.255'
 REVOKE ALL ON test.* FROM mysqltest_1@'127.0.0.1/255.255.255.255';
 DROP USER mysqltest_1@'127.0.0.1/255.255.255.255';
+select user();
+user()
+#
+show processlist;
+Id	User	Host	db	Command	Time	State	Info
+#	root	#	test	Sleep	#		NULL
+#	root	#	test	Query	#	NULL	show processlist

mysql-test/t/skip_name_resolve.test

@@ -8,3 +8,13 @@ REVOKE ALL ON test.* FROM mysqltest_1@'127.0.0.1/255.255.255.255';
 DROP USER mysqltest_1@'127.0.0.1/255.255.255.255';
 
 # End of 4.1 tests
+
+# Bug #13407 "Remote connecting crashes server".
+# Server crashed when one used USER() function in connection for which
+# was impossible to obtain peer hostname.
+connect (con1, 127.0.0.1, root, , test, $MASTER_MYPORT, );
+--replace_column 1 #
+select user();
+--replace_column 1 # 6 # 3 #
+show processlist;
+connection default;

sql/item_strfunc.cc

@@ -1608,7 +1608,7 @@ String *Item_func_user::val_str(String *str)
   else
   {
     user= thd->main_security_ctx.user;
-    host= thd->main_security_ctx.host;
+    host= thd->main_security_ctx.host_or_ip;
   }
 
   // For system threads (e.g. replication SQL thread) user may be empty

sql/mysqld.cc

@@ -4208,7 +4208,7 @@ pthread_handler_decl(handle_connections_shared_memory,arg)
       errmsg= 0;
       goto errorconn;
     }
-    thd->host= my_strdup(my_localhost,MYF(0)); /* Host is unknown */
+    thd->security_ctx->host= my_strdup(my_localhost, MYF(0)); /* Host is unknown */
     create_new_thread(thd);
     connect_number++;
     continue;

sql/sql_show.cc

@@ -1205,7 +1205,7 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
 			"%s:%u", tmp_sctx->host_or_ip, tmp->peer_port);
 	}
 	else
-	  thd_info->host= thd->strdup(tmp_sctx->host);
+	  thd_info->host= thd->strdup(tmp_sctx->host_or_ip);
         if ((thd_info->db=tmp->db))             // Safe test
           thd_info->db=thd->strdup(thd_info->db);
         thd_info->command=(int) tmp->command;