1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*
* 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) 2002-2021 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));
if (context == NULL)
{
printf("PLUGIN: allocating memory for context failed\n");
return NULL;
}
/*
* 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);
}
|
