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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.
+ *
+ * Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@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