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353 lines
11 KiB
353 lines
11 KiB
/* Copyright (c) 2010, 2019, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/**
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@file
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dialog client authentication plugin with examples
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dialog is a general purpose client authentication plugin, it simply
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asks the user the question, as provided by the server and reports
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the answer back to the server. No encryption is involved,
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the answers are sent in clear text.
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Two examples are provided: two_questions server plugin, that asks
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the password and an "Are you sure?" question with a reply "yes, of course".
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It demonstrates the usage of "password" (input is hidden) and "ordinary"
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(input can be echoed) questions, and how to mark the last question,
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to avoid an extra roundtrip.
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And three_attempts plugin that gives the user three attempts to enter
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a correct password. It shows the situation when a number of questions
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is not known in advance.
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*/
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#include "my_config.h"
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#if defined(WIN32) && !defined(RTLD_DEFAULT)
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#define RTLD_DEFAULT GetModuleHandle(NULL)
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#endif
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#include <mysql.h>
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#include <mysql/client_plugin.h>
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#include <mysql/plugin_auth.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "my_compiler.h"
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#ifdef HAVE_DLFCN_H
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#include <dlfcn.h>
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#endif
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#if !defined(_GNU_SOURCE)
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#define _GNU_SOURCE /* for RTLD_DEFAULT */
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#endif
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/**
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first byte of the question string is the question "type".
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It can be an "ordinary" or a "password" question.
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The last bit set marks a last question in the authentication exchange.
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*/
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#define ORDINARY_QUESTION "\2"
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#define LAST_QUESTION "\3"
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#define PASSWORD_QUESTION "\4"
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#define LAST_PASSWORD "\5"
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/********************* SERVER SIDE ****************************************/
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/**
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dialog demo with two questions, one password and one, the last, ordinary.
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*/
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static int two_questions(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info) {
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unsigned char *pkt;
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int pkt_len;
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/* send a password question */
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if (vio->write_packet(
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vio,
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(const unsigned char *)PASSWORD_QUESTION "Password, please:", 18))
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return CR_ERROR;
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/* read the answer */
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if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR;
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info->password_used = PASSWORD_USED_YES;
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/* fail if the password is wrong */
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if (strcmp((const char *)pkt, info->auth_string)) return CR_ERROR;
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/* send the last, ordinary, question */
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if (vio->write_packet(
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vio, (const unsigned char *)LAST_QUESTION "Are you sure ?", 15))
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return CR_ERROR;
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/* read the answer */
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if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR;
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/* check the reply */
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return strcmp((const char *)pkt, "yes, of course") ? CR_ERROR : CR_OK;
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}
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static int generate_auth_string_hash(char *outbuf, unsigned int *buflen,
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const char *inbuf, unsigned int inbuflen) {
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/*
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if buffer specified by server is smaller than the buffer given
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by plugin then return error
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*/
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if (*buflen < inbuflen) return 1;
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strncpy(outbuf, inbuf, inbuflen);
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*buflen = strlen(inbuf);
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return 0;
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}
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static int validate_auth_string_hash(char *const inbuf MY_ATTRIBUTE((unused)),
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unsigned int buflen
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MY_ATTRIBUTE((unused))) {
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return 0;
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}
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static int set_salt(const char *password MY_ATTRIBUTE((unused)),
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unsigned int password_len MY_ATTRIBUTE((unused)),
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unsigned char *salt MY_ATTRIBUTE((unused)),
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unsigned char *salt_len) {
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*salt_len = 0;
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return 0;
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}
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static struct st_mysql_auth two_handler = {
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MYSQL_AUTHENTICATION_INTERFACE_VERSION,
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"dialog", /* requires dialog client plugin */
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two_questions,
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generate_auth_string_hash,
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validate_auth_string_hash,
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set_salt,
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AUTH_FLAG_PRIVILEGED_USER_FOR_PASSWORD_CHANGE,
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NULL};
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/* dialog demo where the number of questions is not known in advance */
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static int three_attempts(MYSQL_PLUGIN_VIO *vio, MYSQL_SERVER_AUTH_INFO *info) {
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unsigned char *pkt;
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int pkt_len, i;
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for (i = 0; i < 3; i++) {
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/* send the prompt */
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if (vio->write_packet(
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vio,
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(const unsigned char *)PASSWORD_QUESTION "Password, please:", 18))
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return CR_ERROR;
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/* read the password */
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if ((pkt_len = vio->read_packet(vio, &pkt)) < 0) return CR_ERROR;
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info->password_used = PASSWORD_USED_YES;
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/*
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finish, if the password is correct.
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note, that we did not mark the prompt packet as "last"
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*/
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if (strcmp((const char *)pkt, info->auth_string) == 0) return CR_OK;
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}
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return CR_ERROR;
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}
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static struct st_mysql_auth three_handler = {
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MYSQL_AUTHENTICATION_INTERFACE_VERSION,
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"dialog", /* requires dialog client plugin */
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three_attempts,
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generate_auth_string_hash,
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validate_auth_string_hash,
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set_salt,
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AUTH_FLAG_PRIVILEGED_USER_FOR_PASSWORD_CHANGE,
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NULL};
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mysql_declare_plugin(dialog){
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MYSQL_AUTHENTICATION_PLUGIN,
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&two_handler,
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"two_questions",
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"Sergei Golubchik",
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"Dialog plugin demo 1",
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PLUGIN_LICENSE_GPL,
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NULL, /* Init */
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NULL, /* Check uninstall */
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NULL, /* Deinit */
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0x0101,
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NULL,
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NULL,
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NULL,
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0,
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},
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{
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MYSQL_AUTHENTICATION_PLUGIN,
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&three_handler,
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"three_attempts",
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"Sergei Golubchik",
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"Dialog plugin demo 2",
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PLUGIN_LICENSE_GPL,
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NULL, /* Init */
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NULL, /* Check uninstall */
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NULL, /* Deinit */
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0x0101,
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NULL,
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NULL,
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NULL,
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0,
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} mysql_declare_plugin_end;
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/********************* CLIENT SIDE ***************************************/
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/*
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This plugin performs a dialog with the user, asking questions and
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reading answers. Depending on the client it may be desirable to do it
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using GUI, or console, with or without curses, or read answers
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from a smartcard, for example.
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To support all this variety, the dialog plugin has a callback function
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"authentication_dialog_ask". If the client has a function of this name
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dialog plugin will use it for communication with the user. Otherwise
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a default fgets() based implementation will be used.
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*/
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/**
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type of the mysql_authentication_dialog_ask function
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@param mysql mysql
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@param type type of the input
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1 - ordinary string input
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2 - password string
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@param prompt prompt
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@param buf a buffer to store the use input
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@param buf_len the length of the buffer
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@retval a pointer to the user input string.
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It may be equal to 'buf' or to 'mysql->password'.
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In all other cases it is assumed to be an allocated
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string, and the "dialog" plugin will free() it.
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*/
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typedef char *(*mysql_authentication_dialog_ask_t)(MYSQL *mysql, int type,
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const char *prompt,
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char *buf, int buf_len);
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static mysql_authentication_dialog_ask_t ask;
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static char *builtin_ask(MYSQL *mysql MY_ATTRIBUTE((unused)),
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int type MY_ATTRIBUTE((unused)), const char *prompt,
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char *buf, int buf_len) {
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char *ptr;
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fputs(prompt, stdout);
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fputc(' ', stdout);
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if (fgets(buf, buf_len, stdin) == NULL) return NULL;
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if ((ptr = strchr(buf, '\n'))) *ptr = 0;
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return buf;
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}
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/**
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The main function of the dialog plugin.
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Read the prompt, ask the question, send the reply, repeat until
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the server is satisfied.
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@note
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1. this plugin shows how a client authentication plugin
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may read a MySQL protocol OK packet internally - which is important
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where a number of packets is not known in advance.
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2. the first byte of the prompt is special. it is not
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shown to the user, but signals whether it is the last question
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(prompt[0] & 1 == 1) or not last (prompt[0] & 1 == 0),
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and whether the input is a password (not echoed).
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3. the prompt is expected to be sent zero-terminated
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*/
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static int perform_dialog(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql) {
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unsigned char *pkt, cmd = 0;
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int pkt_len, res;
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char reply_buf[1024], *reply;
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do {
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/* read the prompt */
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pkt_len = vio->read_packet(vio, &pkt);
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if (pkt_len < 0) return CR_ERROR;
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if (pkt == 0) {
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/*
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in mysql_change_user() the client sends the first packet, so
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the first vio->read_packet() does nothing (pkt == 0).
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We send the "password", assuming the client knows what it's doing.
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(in other words, the dialog plugin should be only set as a default
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authentication plugin on the client if the first question
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asks for a password - which will be sent in clear text, by the way)
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*/
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reply = mysql->passwd;
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} else {
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cmd = *pkt++;
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/* is it MySQL protocol packet ? */
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if (cmd == 0 || cmd == 254)
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return CR_OK_HANDSHAKE_COMPLETE; /* yes. we're done */
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/*
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asking for a password with an empty prompt means mysql->password
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otherwise we ask the user and read the reply
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*/
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if ((cmd >> 1) == 2 && *pkt == 0)
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reply = mysql->passwd;
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else
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reply = ask(mysql, cmd >> 1, (const char *)pkt, reply_buf,
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sizeof(reply_buf));
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if (!reply) return CR_ERROR;
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}
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/* send the reply to the server */
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res = vio->write_packet(vio, (const unsigned char *)reply,
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(int)strlen(reply) + 1);
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if (reply != mysql->passwd && reply != reply_buf) free(reply);
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if (res) return CR_ERROR;
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/* repeat unless it was the last question */
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} while ((cmd & 1) != 1);
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/* the job of reading the ok/error packet is left to the server */
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return CR_OK;
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}
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/**
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initialization function of the dialog plugin
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Pick up the client's authentication_dialog_ask() function, if exists,
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or fall back to the default implementation.
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*/
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static int init_dialog(char *unused1 MY_ATTRIBUTE((unused)),
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size_t unused2 MY_ATTRIBUTE((unused)),
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int unused3 MY_ATTRIBUTE((unused)),
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va_list unused4 MY_ATTRIBUTE((unused))) {
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void *sym = dlsym(RTLD_DEFAULT, "mysql_authentication_dialog_ask");
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ask = sym ? (mysql_authentication_dialog_ask_t)sym : builtin_ask;
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return 0;
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}
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mysql_declare_client_plugin(AUTHENTICATION) "dialog", "Sergei Golubchik",
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"Dialog Client Authentication Plugin", {0, 1, 0}, "GPL", NULL,
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init_dialog, NULL, NULL, perform_dialog, NULL mysql_end_client_plugin;
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