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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
* |
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*
* 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
*/
#ifndef FRAGMENT_H
#define FRAGMENT_H
#ifdef ENABLE_FRAGMENT
#include "common.h"
#include "buffer.h"
#include "interval.h"
#include "mtu.h"
#include "shaper.h"
#include "error.h"
#define N_FRAG_BUF 25 /* number of packet buffers */
#define FRAG_TTL_SEC 10 /* number of seconds time-to-live for a fragment */
#define FRAG_WAKEUP_INTERVAL 5 /* wakeup code called once per n seconds */
struct fragment {
bool defined;
int max_frag_size; /* maximum size of each fragment */
/*
* 32 bit array corresponding to each fragment. A 1 bit in element n means that
* the fragment n has been received. Needs to have at least MAX_FRAGS bits.
*/
# define FRAG_MAP_MASK 0xFFFFFFFF
# define MAX_FRAGS 32 /* maximum number of fragments per packet */
unsigned int map;
time_t timestamp; /* timestamp for time-to-live purposes */
struct buffer buf; /* fragment assembly buffer for received datagrams */
};
struct fragment_list {
int seq_id;
int index;
struct fragment fragments[N_FRAG_BUF];
};
struct fragment_master {
struct event_timeout wakeup; /* when should main openvpn event loop wake us up */
/* true if the OS has explicitly recommended an MTU value */
bool received_os_mtu_hint;
/* a sequence ID describes a set of fragments that make up one datagram */
# define N_SEQ_ID 256 /* sequence number wraps to 0 at this value (should be a power of 2) */
int outgoing_seq_id; /* sent as FRAG_SEQ_ID below */
/* outgoing packet is possibly sent as a series of fragments */
# define MAX_FRAG_PKT_SIZE 65536 /* maximum packet size */
int outgoing_frag_size; /* sent to peer via FRAG_SIZE when FRAG_YES_LAST set */
int outgoing_frag_id; /* each fragment in a datagram is numbered 0 to MAX_FRAGS-1 */
struct buffer outgoing; /* outgoing datagram, free if current_frag_id == 0 */
struct buffer outgoing_return; /* buffer to return outgoing fragment */
/* incoming fragments from remote */
struct fragment_list incoming;
};
/*
* Fragment header sent over the wire.
*/
typedef uint32_t fragment_header_type;
/* convert a fragment_header_type from host to network order */
#define hton_fragment_header_type(x) htonl(x)
/* convert a fragment_header_type from network to host order */
#define ntoh_fragment_header_type(x) ntohl(x)
/* FRAG_TYPE 2 bits */
#define FRAG_TYPE_MASK 0x00000003
#define FRAG_TYPE_SHIFT 0
#define FRAG_WHOLE 0 /* packet is whole, FRAG_N_PACKETS_RECEIVED echoed back to peer */
#define FRAG_YES_NOTLAST 1 /* packet is a fragment, but is not the last fragment,
FRAG_N_PACKETS_RECEIVED set as above */
#define FRAG_YES_LAST 2 /* packet is the last fragment, FRAG_SIZE = size of non-last frags */
#define FRAG_TEST 3 /* control packet for establishing MTU size (not implemented yet) */
/* FRAG_SEQ_ID 8 bits */
#define FRAG_SEQ_ID_MASK 0x000000ff
#define FRAG_SEQ_ID_SHIFT 2
/* FRAG_ID 5 bits */
#define FRAG_ID_MASK 0x0000001f
#define FRAG_ID_SHIFT 10
/*
* FRAG_SIZE 14 bits
*
* IF FRAG_YES_LAST (FRAG_SIZE):
* The max size of a fragment. If a fragment is not the last fragment in the packet,
* then the fragment size is guaranteed to be equal to the max fragment size. Therefore,
* max_frag_size is only sent over the wire if FRAG_LAST is set. Otherwise it is assumed
* to be the actual fragment size received.
*/
/* FRAG_SIZE 14 bits */
#define FRAG_SIZE_MASK 0x00003fff
#define FRAG_SIZE_SHIFT 15
#define FRAG_SIZE_ROUND_SHIFT 2 /* fragment/datagram sizes represented as multiple of 4 */
#define FRAG_SIZE_ROUND_MASK ((1 << FRAG_SIZE_ROUND_SHIFT) - 1)
/*
* FRAG_EXTRA 16 bits
*
* IF FRAG_WHOLE or FRAG_YES_NOTLAST, these 16 bits are available (not currently used)
*/
/* FRAG_EXTRA 16 bits */
#define FRAG_EXTRA_MASK 0x0000ffff
#define FRAG_EXTRA_SHIFT 15
/*
* Public functions
*/
struct fragment_master *fragment_init (struct frame *frame);
void fragment_frame_init (struct fragment_master *f, const struct frame *frame);
void fragment_free (struct fragment_master *f);
void fragment_incoming (struct fragment_master *f, struct buffer *buf,
const struct frame* frame);
void fragment_outgoing (struct fragment_master *f, struct buffer *buf,
const struct frame* frame);
bool fragment_ready_to_send (struct fragment_master *f, struct buffer *buf,
const struct frame* frame);
/*
* Private functions.
*/
void fragment_wakeup (struct fragment_master *f, struct frame *frame);
/*
* Inline functions
*/
static inline void
fragment_housekeeping (struct fragment_master *f, struct frame *frame, struct timeval *tv)
{
if (event_timeout_trigger (&f->wakeup, tv, ETT_DEFAULT))
fragment_wakeup (f, frame);
}
static inline bool
fragment_outgoing_defined (struct fragment_master *f)
{
return f->outgoing.len > 0;
}
#endif
#endif |