pluggable auth with plugin examples

Makefile.am:
  add new API files to the check_abi rule,
  remove duplicates
client/CMakeLists.txt:
  now a client can use dlopen too
client/Makefile.am:
  be csh-friendly
include/my_global.h:
  add dummy plugs for dlopen and co.
  for the code that needs them to work in static builds
mysys/Makefile.am:
  be csh-friendly
plugin/auth/dialog.c:
  typo fixed

include/mysql/plugin_auth_common.h

@@ -0,0 +1,105 @@
+#ifndef MYSQL_PLUGIN_AUTH_COMMON_INCLUDED
+/* Copyright (C) 2010 Sergei Golubchik and Monty Program Ab
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+/**
+  @file
+
+  This file defines constants and data structures that are the same for
+  both client- and server-side authentication plugins.
+*/
+#define MYSQL_PLUGIN_AUTH_COMMON_INCLUDED
+
+/** the max allowed length for a user name */
+#define MYSQL_USERNAME_LENGTH 48
+
+/**
+  return values of the plugin authenticate_user() method.
+*/
+
+/**
+  Authentication failed. Additionally, all other CR_xxx values
+  (libmysql error code) can be used too.
+
+  The client plugin may set the error code and the error message directly
+  in the MYSQL structure and return CR_ERROR. If a CR_xxx specific error
+  code was returned, an error message in the MYSQL structure will be
+  overwritten. If CR_ERROR is returned without setting the error in MYSQL,
+  CR_UNKNOWN_ERROR will be user.
+*/
+#define CR_ERROR 0
+/**
+  Authentication (client part) was successful. It does not mean that the
+  authentication as a whole was successful, usually it only means
+  that the client was able to send the user name and the password to the
+  server. If CR_OK is returned, the libmysql reads the next packet expecting
+  it to be one of OK, ERROR, or CHANGE_PLUGIN packets.
+*/
+#define CR_OK -1
+/**
+  Authentication was successful.
+  It means that the client has done its part successfully and also that
+  a plugin has read the last packet (one of OK, ERROR, CHANGE_PLUGIN).
+  In this case, libmysql will not read a packet from the server,
+  but it will use the data at mysql->net.read_pos.
+
+  A plugin may return this value if the number of roundtrips in the
+  authentication protocol is not known in advance, and the client plugin
+  needs to read one packet more to determine if the authentication is finished
+  or not.
+*/
+#define CR_OK_HANDSHAKE_COMPLETE -2
+
+typedef struct st_plugin_vio_info
+{
+  enum { MYSQL_VIO_INVALID, MYSQL_VIO_TCP, MYSQL_VIO_SOCKET,
+         MYSQL_VIO_PIPE, MYSQL_VIO_MEMORY } protocol;
+  int socket;     /**< it's set, if the protocol is SOCKET or TCP */
+#ifdef _WIN32
+  HANDLE handle;  /**< it's set, if the protocol is PIPE or MEMORY */
+#endif
+} MYSQL_PLUGIN_VIO_INFO;
+
+/**
+  Provides plugin access to communication channel
+*/
+typedef struct st_plugin_vio
+{
+  /**
+    Plugin provides a pointer reference and this function sets it to the
+    contents of any incoming packet. Returns the packet length, or -1 if
+    the plugin should terminate.
+  */
+  int (*read_packet)(struct st_plugin_vio *vio, 
+                     unsigned char **buf);
+  
+  /**
+    Plugin provides a buffer with data and the length and this
+    function sends it as a packet. Returns 0 on success, 1 on failure.
+  */
+  int (*write_packet)(struct st_plugin_vio *vio, 
+                      const unsigned char *packet, 
+                      int packet_len);
+
+  /**
+    Fills in a st_plugin_vio_info structure, providing the information
+    about the connection.
+  */
+  void (*info)(struct st_plugin_vio *vio, struct st_plugin_vio_info *info);
+
+} MYSQL_PLUGIN_VIO;
+
+#endif
+