summaryrefslogtreecommitdiff
path: root/src/openvpn/forward.h
blob: 1830a00b344645883e47b734c6fffd59fb73c215 (plain)
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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
/*
 *  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) 2002-2010 OpenVPN Technologies, 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 (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


/**
 * @file
 * Interface functions to the internal and external multiplexers.
 */


#ifndef FORWARD_H
#define FORWARD_H

#include "openvpn.h"
#include "occ.h"
#include "ping.h"

#define TUN_OUT(c)      (BLEN(&(c)->c2.to_tun) > 0)
#define LINK_OUT(c)     (BLEN(&(c)->c2.to_link) > 0)
#define ANY_OUT(c)      (TUN_OUT(c) || LINK_OUT(c))

#ifdef ENABLE_FRAGMENT
#define TO_LINK_FRAG(c) ((c)->c2.fragment && fragment_outgoing_defined ((c)->c2.fragment))
#else
#define TO_LINK_FRAG(c) (false)
#endif

#define TO_LINK_DEF(c)  (LINK_OUT(c) || TO_LINK_FRAG(c))

#define IOW_TO_TUN          (1<<0)
#define IOW_TO_LINK         (1<<1)
#define IOW_READ_TUN        (1<<2)
#define IOW_READ_LINK       (1<<3)
#define IOW_SHAPER          (1<<4)
#define IOW_CHECK_RESIDUAL  (1<<5)
#define IOW_FRAG            (1<<6)
#define IOW_MBUF            (1<<7)
#define IOW_READ_TUN_FORCE  (1<<8)
#define IOW_WAIT_SIGNAL     (1<<9)

#define IOW_READ            (IOW_READ_TUN|IOW_READ_LINK)


void pre_select (struct context *c);
void process_io (struct context *c);

const char *wait_status_string (struct context *c, struct gc_arena *gc);
void show_wait_status (struct context *c);


/**********************************************************************/
/**
 * Process a data channel packet that will be sent through a VPN tunnel.
 * @ingroup data_control
 *
 * This function controls the processing of a data channel packet which
 * will be sent through a VPN tunnel to a remote OpenVPN peer.  It's
 * general structure is as follows:
 * - Check that the client authentication has succeeded; if not, drop the
 *   packet.
 * - If the \a comp_frag argument is true:
 *   - Call \c lzo_compress() of the \link Data Channel Compression
 *     module\endlink to (possibly) compress the packet.
 *   - Call \c fragment_outgoing() of the \link Data Channel Fragmentation
 *     module\endlink to (possibly) fragment the packet.
 * - Activate the \link Data Channel Crypto module\endlink to perform
 *   security operations on the packet.
 *   - Call \c tls_pre_encrypt() to choose the appropriate security
 *     parameters for this packet.
 *   - Call \c openvpn_encrypt() to encrypt and HMAC signed the packet.
 *   - Call \c tls_post_encrypt() to prepend the one-byte OpenVPN header
 *     and do some TLS accounting.
 * - Place the resulting packet in \c c->c2.to_link so that it can be sent
 *   over the external network interface to its remote destination by the
 *   \link external_multiplexer External Multiplexer\endlink.
 *
 * @param c - The context structure of the VPN tunnel associated with this
 *     packet.
 * @param comp_frag - Whether to do packet compression and fragmentation.
 *     This flag is set to true the first time a packet is processed.  If
 *     the packet then gets fragmented, this function will be called again
 *     once for each remaining fragment with this parameter set to false.
 */
void encrypt_sign (struct context *c, bool comp_frag);


/**********************************************************************/
/**
 * Read a packet from the external network interface.
 * @ingroup external_multiplexer
 *
 * The packet read from the external network interface is stored in \c
 * c->c2.buf and its source address in \c c->c2.from.  If an error
 * occurred, the length of \c c->c2.buf will be 0.
 *
 * OpenVPN running as client or as UDP server only has a single external
 * network socket, so this function can be called with the single (client
 * mode) or top level (UDP server) context as its argument. OpenVPN
 * running as TCP server, on the other hand, has a network socket for each
 * active VPN tunnel.  In that case this function must be called with the
 * context associated with the appropriate VPN tunnel for which data is
 * available to be read.
 *
 * @param c - The context structure which contains the external
 *     network socket from which to read incoming packets.
 */
void read_incoming_link (struct context *c);


/**
 * Process a packet read from the external network interface.
 * @ingroup external_multiplexer
 *
 * This function controls the processing of a data channel packet which
 * has come out of a VPN tunnel.  It's high-level structure is as follows:
 * - Verify that a nonzero length packet has been received from a valid
 *   source address for the given context \a c.
 * - Call \c tls_pre_decrypt(), which splits data channel and control
 *   channel packets:
 *   - If a data channel packet, the appropriate security parameters are
 *     loaded.
 *   - If a control channel packet, this function process is it and
 *     afterwards sets the packet's buffer length to 0, so that the data
 *     channel processing steps below will ignore it.
 * - Call \c openvpn_decrypt() of the \link data_crypto Data Channel
 *   Crypto module\endlink to authenticate and decrypt the packet using
 *   the security parameters loaded by \c tls_pre_decrypt() above.
 * - Call \c fragment_incoming() of the \link fragmentation Data Channel
 *   Fragmentation module\endlink to reassemble the packet if it's
 *   fragmented.
 * - Call \c lzo_decompress() of the \link compression Data Channel
 *   Compression module\endlink to decompress the packet if it's
 *   compressed.
 * - Place the resulting packet in \c c->c2.to_tun so that it can be sent
 *   over the virtual tun/tap network interface to its local destination
 *   by the \link internal_multiplexer Internal Multiplexer\endlink.
 *
 * @param c - The context structure of the VPN tunnel associated with the
 *     packet.
 */
void process_incoming_link (struct context *c);


/**
 * Write a packet to the external network interface.
 * @ingroup external_multiplexer
 *
 * This function writes the packet stored in \c c->c2.to_link to the
 * external network device contained within \c c->c1.link_socket.
 *
 * If an error occurs, it is logged and the packet is dropped.
 *
 * @param c - The context structure of the VPN tunnel associated with the
 *     packet.
 */
void process_outgoing_link (struct context *c);


/**************************************************************************/
/**
 * Read a packet from the virtual tun/tap network interface.
 * @ingroup internal_multiplexer
 *
 * This function reads a packet from the virtual tun/tap network device \c
 * c->c1.tuntap and stores it in \c c->c2.buf.
 *
 * If an error occurs, it is logged and the packet is dropped.
 *
 * @param c - The context structure in which to store the received
 *     packet.
 */
void read_incoming_tun (struct context *c);


/**
 * Process a packet read from the virtual tun/tap network interface.
 * @ingroup internal_multiplexer
 *
 * This function calls \c encrypt_sign() of the \link data_control Data
 * Channel Control module\endlink to process the packet.
 *
 * If an error occurs, it is logged and the packet is dropped.
 *
 * @param c - The context structure of the VPN tunnel associated with the
 *     packet.
 */
void process_incoming_tun (struct context *c);


/**
 * Write a packet to the virtual tun/tap network interface.
 * @ingroup internal_multiplexer
 *
 * This function writes the packet stored in \c c->c2.to_tun to the
 * virtual tun/tap network device \c c->c1.tuntap.
 *
 * If an error occurs, it is logged and the packet is dropped.
 *
 * @param c - The context structure of the VPN tunnel associated with
 *     the packet.
 */
void process_outgoing_tun (struct context *c);


/**************************************************************************/

bool send_control_channel_string (struct context *c, const char *str, int msglevel);

#define PIPV4_PASSTOS         (1<<0)
#define PIP_MSSFIX            (1<<1)         /* v4 and v6 */
#define PIPV4_OUTGOING        (1<<2)
#define PIPV4_EXTRACT_DHCP_ROUTER (1<<3)
#define PIPV4_CLIENT_NAT      (1<<4)

void process_ip_header (struct context *c, unsigned int flags, struct buffer *buf);

#if P2MP
void schedule_exit (struct context *c, const int n_seconds, const int signal);
#endif

#endif /* FORWARD_H */