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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
* This file implements a simple OpenVPN plugin module which
* will examine the username/password provided by a client,
* and make an accept/deny determination. Will run
* on Windows or *nix.
*
* See the README file for build instructions.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "openvpn-plugin.h"
/*
* Our context, where we keep our state.
*/
struct plugin_context {
const char *username;
const char *password;
};
/*
* Given an environmental variable name, search
* the envp array for its value, returning it
* if found or NULL otherwise.
*/
static const char *
get_env(const char *name, const char *envp[])
{
if (envp)
{
int i;
const int namelen = strlen(name);
for (i = 0; envp[i]; ++i)
{
if (!strncmp(envp[i], name, namelen))
{
const char *cp = envp[i] + namelen;
if (*cp == '=')
{
return cp + 1;
}
}
}
}
return NULL;
}
OPENVPN_EXPORT openvpn_plugin_handle_t
openvpn_plugin_open_v1(unsigned int *type_mask, const char *argv[], const char *envp[])
{
struct plugin_context *context;
/*
* Allocate our context
*/
context = (struct plugin_context *) calloc(1, sizeof(struct plugin_context));
/*
* Set the username/password we will require.
*/
context->username = "foo";
context->password = "bar";
/*
* We are only interested in intercepting the
* --auth-user-pass-verify callback.
*/
*type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY);
return (openvpn_plugin_handle_t) context;
}
OPENVPN_EXPORT int
openvpn_plugin_func_v1(openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[])
{
struct plugin_context *context = (struct plugin_context *) handle;
/* get username/password from envp string array */
const char *username = get_env("username", envp);
const char *password = get_env("password", envp);
/* check entered username/password against what we require */
if (username && !strcmp(username, context->username)
&& password && !strcmp(password, context->password))
{
return OPENVPN_PLUGIN_FUNC_SUCCESS;
}
else
{
return OPENVPN_PLUGIN_FUNC_ERROR;
}
}
OPENVPN_EXPORT void
openvpn_plugin_close_v1(openvpn_plugin_handle_t handle)
{
struct plugin_context *context = (struct plugin_context *) handle;
free(context);
}
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