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Diffstat (limited to 'fragment.h')
| -rw-r--r-- | fragment.h | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/fragment.h b/fragment.h new file mode 100644 index 0000000..fc2b1b8 --- /dev/null +++ b/fragment.h @@ -0,0 +1,188 @@ +/* + * 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. + * + * 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 + */ + +#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 |