move authentication_windows_client and mysql_clear_password clear client auth plugins

out of libmysql into separate dynamic plugins in the plugin/ directory.

move dialog and auth_socket plugins out of the plugin directory with examples into
dedicated directories in plugin/

plugin/auth_examples/dialog_examples.c

@@ -0,0 +1,154 @@
+/* Copyright (C) 2010 Sergei Golubchik and Monty Program Ab
+   Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+
+    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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
+
+/**
+  @file
+
+  examples for dialog client authentication plugin
+
+  Two examples are provided: two_questions server plugin, that asks
+  the password and an "Are you sure?" question with a reply "yes, of course".
+  It demonstrates the usage of "password" (input is hidden) and "ordinary"
+  (input can be echoed) questions, and how to mark the last question,
+  to avoid an extra roundtrip.
+
+  And three_attempts plugin that gives the user three attempts to enter
+  a correct password. It shows the situation when a number of questions
+  is not known in advance.
+*/
+
+#include <mysql/plugin_auth.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <mysql/auth_dialog_client.h>
+
+/********************* SERVER SIDE ****************************************/
+
+/**
+  dialog demo with two questions, one password and one, the last, ordinary.
+*/
+static int two_questions(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info)
+{
+  unsigned char *pkt;
+  int pkt_len;
+
+  /* send a password question */
+  if (vio->write_packet(vio,
+                        (const unsigned char *) PASSWORD_QUESTION "Password, please:",
+                        18))
+    return CR_ERROR;
+
+  /* read the answer */
+  if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+    return CR_ERROR;
+
+  info->password_used= PASSWORD_USED_YES;
+
+  /* fail if the password is wrong */
+  if (strcmp((const char *) pkt, info->auth_string))
+    return CR_ERROR;
+
+  /* send the last, ordinary, question */
+  if (vio->write_packet(vio,
+                        (const unsigned char *) LAST_QUESTION "Are you sure ?",
+                        15))
+    return CR_ERROR;
+
+  /* read the answer */
+  if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+    return CR_ERROR;
+
+  /* check the reply */
+  return strcmp((const char *) pkt, "yes, of course") ? CR_ERROR : CR_OK;
+}
+
+static struct st_mysql_auth two_handler=
+{
+  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
+  "dialog", /* requires dialog client plugin */
+  two_questions
+};
+
+/* dialog demo where the number of questions is not known in advance */
+static int three_attempts(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info)
+{
+  unsigned char *pkt;
+  int pkt_len, i;
+
+  for (i= 0; i < 3; i++)
+  {
+    /* send the prompt */
+    if (vio->write_packet(vio, 
+		(const unsigned char *) PASSWORD_QUESTION "Password, please:", 18))
+      return CR_ERROR;
+
+    /* read the password */
+    if ((pkt_len= vio->read_packet(vio, &pkt)) < 0)
+      return CR_ERROR;
+
+    info->password_used= PASSWORD_USED_YES;
+
+    /*
+      finish, if the password is correct.
+      note, that we did not mark the prompt packet as "last"
+    */
+    if (strcmp((const char *) pkt, info->auth_string) == 0)
+      return CR_OK;
+  }
+
+  return CR_ERROR;
+}
+
+static struct st_mysql_auth three_handler=
+{
+  MYSQL_AUTHENTICATION_INTERFACE_VERSION,
+  "dialog", /* requires dialog client plugin */
+  three_attempts 
+};
+
+mysql_declare_plugin(dialog)
+{
+  MYSQL_AUTHENTICATION_PLUGIN,
+  &two_handler,
+  "two_questions",
+  "Sergei Golubchik",
+  "Dialog plugin demo 1",
+  PLUGIN_LICENSE_GPL,
+  NULL,
+  NULL,
+  0x0100,
+  NULL,
+  NULL,
+  NULL
+},
+{
+  MYSQL_AUTHENTICATION_PLUGIN,
+  &three_handler,
+  "three_attempts",
+  "Sergei Golubchik",
+  "Dialog plugin demo 2",
+  PLUGIN_LICENSE_GPL,
+  NULL,
+  NULL,
+  0x0100,
+  NULL,
+  NULL,
+  NULL
+}
+mysql_declare_plugin_end;
+