MDEV-4088 Replication 10.0 -> 5.5 fails

Author: Sergei Golubchik

include/mysql_com.h

@@ -34,6 +34,13 @@
 #define MYSQL50_TABLE_NAME_PREFIX_LENGTH  (sizeof(MYSQL50_TABLE_NAME_PREFIX)-1)
 #define SAFE_NAME_LEN (NAME_LEN + MYSQL50_TABLE_NAME_PREFIX_LENGTH)
 
+#ifdef EMBEDDED_LIBRARY
+#define RPL_VERSION_HACK ""
+#else
+/* this version must be the one that *does not* support pluggable auth */
+#define RPL_VERSION_HACK "5.5.5-"
+#endif
+
 #define SERVER_VERSION_LENGTH 60
 #define SQLSTATE_LENGTH 5
 #define LIST_PROCESS_HOST_LEN 64

sql-common/client.c

@@ -3416,6 +3416,12 @@ CLI_MYSQL_REAL_CONNECT(MYSQL *mysql,const char *host, const char *user,
   strmov(mysql->server_version,(char*) net->read_pos+1);
   mysql->port=port;
 
+  /* remove the rpl hack from the version string */
+  if (mysql->server_capabilities & CLIENT_PLUGIN_AUTH &&
+      strncmp(mysql->server_version, RPL_VERSION_HACK,
+              sizeof(RPL_VERSION_HACK) - 1) == 0)
+    mysql->server_version+= sizeof(RPL_VERSION_HACK) - 1;
+
   if (pkt_end >= end + SCRAMBLE_LENGTH - SCRAMBLE_LENGTH_323 + 1)
   {
     /*

sql/sql_acl.cc

@@ -7957,7 +7957,7 @@ static bool send_server_handshake_packet(MPVIO_EXT *mpvio,
     data_len= SCRAMBLE_LENGTH;
   }
 
-  end= strnmov(end, server_version, SERVER_VERSION_LENGTH) + 1;
+  end= strxnmov(end, SERVER_VERSION_LENGTH, RPL_VERSION_HACK, server_version, NullS) + 1;
   int4store((uchar*) end, mpvio->thd->thread_id);
   end+= 4;