diff options
Diffstat (limited to 'fragment.c')
| -rw-r--r-- | fragment.c | 408 |
1 files changed, 0 insertions, 408 deletions
diff --git a/fragment.c b/fragment.c deleted file mode 100644 index 5ef3a47..0000000 --- a/fragment.c +++ /dev/null @@ -1,408 +0,0 @@ -/* - * 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 - */ - -#include "syshead.h" - -#ifdef ENABLE_FRAGMENT - -#include "misc.h" -#include "fragment.h" -#include "integer.h" -#include "memdbg.h" - -#define FRAG_ERR(s) { errmsg = s; goto error; } - -static void -fragment_list_buf_init (struct fragment_list *list, const struct frame *frame) -{ - int i; - for (i = 0; i < N_FRAG_BUF; ++i) - list->fragments[i].buf = alloc_buf (BUF_SIZE (frame)); -} - -static void -fragment_list_buf_free (struct fragment_list *list) -{ - int i; - for (i = 0; i < N_FRAG_BUF; ++i) - free_buf (&list->fragments[i].buf); -} - -/* - * Given a sequence ID number, get a fragment buffer. Use a sliding window, - * similar to packet_id code. - */ -static struct fragment * -fragment_list_get_buf (struct fragment_list *list, int seq_id) -{ - int diff; - if (abs (diff = modulo_subtract (seq_id, list->seq_id, N_SEQ_ID)) >= N_FRAG_BUF) - { - int i; - for (i = 0; i < N_FRAG_BUF; ++i) - list->fragments[i].defined = false; - list->index = 0; - list->seq_id = seq_id; - diff = 0; - } - while (diff > 0) - { - list->fragments[list->index = modulo_add (list->index, 1, N_FRAG_BUF)].defined = false; - list->seq_id = modulo_add (list->seq_id, 1, N_SEQ_ID); - --diff; - } - return &list->fragments[modulo_add (list->index, diff, N_FRAG_BUF)]; -} - -struct fragment_master * -fragment_init (struct frame *frame) -{ - struct fragment_master *ret; - - /* code that initializes other parts of - fragment_master assume an initial CLEAR */ - ALLOC_OBJ_CLEAR (ret, struct fragment_master); - - /* add in the size of our contribution to the expanded frame size */ - frame_add_to_extra_frame (frame, sizeof(fragment_header_type)); - - /* - * Outgoing sequence ID is randomized to reduce - * the probability of sequence number collisions - * when openvpn sessions are restarted. This is - * not done out of any need for security, as all - * fragmentation control information resides - * inside of the encrypted/authenticated envelope. - */ - ret->outgoing_seq_id = (int)get_random() & (N_SEQ_ID - 1); - - event_timeout_init (&ret->wakeup, FRAG_WAKEUP_INTERVAL, now); - - return ret; -} - -void -fragment_free (struct fragment_master *f) -{ - fragment_list_buf_free (&f->incoming); - free_buf (&f->outgoing); - free_buf (&f->outgoing_return); - free (f); -} - -void -fragment_frame_init (struct fragment_master *f, const struct frame *frame) -{ - fragment_list_buf_init (&f->incoming, frame); - f->outgoing = alloc_buf (BUF_SIZE (frame)); - f->outgoing_return = alloc_buf (BUF_SIZE (frame)); -} - -/* - * Accept an incoming datagram (which may be a fragment) from remote. - * If the datagram is whole (i.e not a fragment), pass through. - * If the datagram is a fragment, join with other fragments received so far. - * If a fragment fully completes the datagram, return the datagram. - */ -void -fragment_incoming (struct fragment_master *f, struct buffer *buf, - const struct frame* frame) -{ - const char *errmsg = NULL; - fragment_header_type flags = 0; - int frag_type = 0; - - if (buf->len > 0) - { - /* get flags from packet head */ - if (!buf_read (buf, &flags, sizeof (flags))) - FRAG_ERR ("flags not found in packet"); - flags = ntoh_fragment_header_type (flags); - - /* get fragment type from flags */ - frag_type = ((flags >> FRAG_TYPE_SHIFT) & FRAG_TYPE_MASK); - -#if 0 - /* - * If you want to extract FRAG_EXTRA_MASK/FRAG_EXTRA_SHIFT bits, - * do it here. - */ - if (frag_type == FRAG_WHOLE || frag_type == FRAG_YES_NOTLAST) - { - } -#endif - - /* handle the fragment type */ - if (frag_type == FRAG_WHOLE) - { - dmsg (D_FRAG_DEBUG, - "FRAG_IN buf->len=%d type=FRAG_WHOLE flags=" - fragment_header_format, - buf->len, - flags); - - if (flags & (FRAG_SEQ_ID_MASK | FRAG_ID_MASK)) - FRAG_ERR ("spurrious FRAG_WHOLE flags"); - } - else if (frag_type == FRAG_YES_NOTLAST || frag_type == FRAG_YES_LAST) - { - const int seq_id = ((flags >> FRAG_SEQ_ID_SHIFT) & FRAG_SEQ_ID_MASK); - const int n = ((flags >> FRAG_ID_SHIFT) & FRAG_ID_MASK); - const int size = ((frag_type == FRAG_YES_LAST) - ? (int)(((flags >> FRAG_SIZE_SHIFT) & FRAG_SIZE_MASK) << FRAG_SIZE_ROUND_SHIFT) - : buf->len); - - /* get the appropriate fragment buffer based on received seq_id */ - struct fragment *frag = fragment_list_get_buf (&f->incoming, seq_id); - - dmsg (D_FRAG_DEBUG, - "FRAG_IN len=%d type=%d seq_id=%d frag_id=%d size=%d flags=" - fragment_header_format, - buf->len, - frag_type, - seq_id, - n, - size, - flags); - - /* make sure that size is an even multiple of 1<<FRAG_SIZE_ROUND_SHIFT */ - if (size & FRAG_SIZE_ROUND_MASK) - FRAG_ERR ("bad fragment size"); - - /* is this the first fragment for our sequence number? */ - if (!frag->defined || (frag->defined && frag->max_frag_size != size)) - { - frag->defined = true; - frag->max_frag_size = size; - frag->map = 0; - ASSERT (buf_init (&frag->buf, FRAME_HEADROOM_ADJ (frame, FRAME_HEADROOM_MARKER_FRAGMENT))); - } - - /* copy the data to fragment buffer */ - if (!buf_copy_range (&frag->buf, n * size, buf, 0, buf->len)) - FRAG_ERR ("fragment buffer overflow"); - - /* set elements in bit array to reflect which fragments have been received */ - frag->map |= (((frag_type == FRAG_YES_LAST) ? FRAG_MAP_MASK : 1) << n); - - /* update timestamp on partially built datagram */ - frag->timestamp = now; - - /* received full datagram? */ - if ((frag->map & FRAG_MAP_MASK) == FRAG_MAP_MASK) - { - frag->defined = false; - *buf = frag->buf; - } - else - { - buf->len = 0; - } - } - else if (frag_type == FRAG_TEST) - { - FRAG_ERR ("FRAG_TEST not implemented"); - } - else - { - FRAG_ERR ("unknown fragment type"); - } - } - - return; - - error: - if (errmsg) - msg (D_FRAG_ERRORS, "FRAG_IN error flags=" fragment_header_format ": %s", flags, errmsg); - buf->len = 0; - return; -} - -/* pack fragment parms into a uint32_t and prepend to buffer */ -static void -fragment_prepend_flags (struct buffer *buf, - int type, - int seq_id, - int frag_id, - int frag_size) -{ - fragment_header_type flags = ((type & FRAG_TYPE_MASK) << FRAG_TYPE_SHIFT) - | ((seq_id & FRAG_SEQ_ID_MASK) << FRAG_SEQ_ID_SHIFT) - | ((frag_id & FRAG_ID_MASK) << FRAG_ID_SHIFT); - - if (type == FRAG_WHOLE || type == FRAG_YES_NOTLAST) - { - /* - * If you want to set FRAG_EXTRA_MASK/FRAG_EXTRA_SHIFT bits, - * do it here. - */ - dmsg (D_FRAG_DEBUG, - "FRAG_OUT len=%d type=%d seq_id=%d frag_id=%d frag_size=%d flags=" - fragment_header_format, - buf->len, type, seq_id, frag_id, frag_size, flags); - } - else - { - flags |= (((frag_size >> FRAG_SIZE_ROUND_SHIFT) & FRAG_SIZE_MASK) << FRAG_SIZE_SHIFT); - - dmsg (D_FRAG_DEBUG, - "FRAG_OUT len=%d type=%d seq_id=%d frag_id=%d frag_size=%d flags=" - fragment_header_format, - buf->len, type, seq_id, frag_id, frag_size, flags); - } - - flags = hton_fragment_header_type (flags); - ASSERT (buf_write_prepend (buf, &flags, sizeof (flags))); -} - -/* - * Without changing the number of fragments, return a possibly smaller - * max fragment size that will allow for the last fragment to be of - * similar size as previous fragments. - */ -static inline int -optimal_fragment_size (int len, int max_frag_size) -{ - const int mfs_aligned = (max_frag_size & ~FRAG_SIZE_ROUND_MASK); - const int div = len / mfs_aligned; - const int mod = len % mfs_aligned; - - if (div > 0 && mod > 0 && mod < mfs_aligned * 3 / 4) - return min_int (mfs_aligned, (max_frag_size - ((max_frag_size - mod) / (div + 1)) - + FRAG_SIZE_ROUND_MASK) & ~FRAG_SIZE_ROUND_MASK); - else - return mfs_aligned; -} - -/* process an outgoing datagram, possibly breaking it up into fragments */ -void -fragment_outgoing (struct fragment_master *f, struct buffer *buf, - const struct frame* frame) -{ - const char *errmsg = NULL; - if (buf->len > 0) - { - /* The outgoing buffer should be empty so we can put new data in it */ - if (f->outgoing.len) - msg (D_FRAG_ERRORS, "FRAG: outgoing buffer is not empty, len=[%d,%d]", - buf->len, f->outgoing.len); - if (buf->len > PAYLOAD_SIZE_DYNAMIC(frame)) /* should we fragment? */ - { - /* - * Send the datagram as a series of 2 or more fragments. - */ - f->outgoing_frag_size = optimal_fragment_size (buf->len, PAYLOAD_SIZE_DYNAMIC(frame)); - if (buf->len > f->outgoing_frag_size * MAX_FRAGS) - FRAG_ERR ("too many fragments would be required to send datagram"); - ASSERT (buf_init (&f->outgoing, FRAME_HEADROOM (frame))); - ASSERT (buf_copy (&f->outgoing, buf)); - f->outgoing_seq_id = modulo_add (f->outgoing_seq_id, 1, N_SEQ_ID); - f->outgoing_frag_id = 0; - buf->len = 0; - ASSERT (fragment_ready_to_send (f, buf, frame)); - } - else - { - /* - * Send the datagram whole. - */ - fragment_prepend_flags (buf, - FRAG_WHOLE, - 0, - 0, - 0); - } - } - return; - - error: - if (errmsg) - msg (D_FRAG_ERRORS, "FRAG_OUT error, len=%d frag_size=%d MAX_FRAGS=%d: %s", - buf->len, f->outgoing_frag_size, MAX_FRAGS, errmsg); - buf->len = 0; - return; -} - -/* return true (and set buf) if we have an outgoing fragment which is ready to send */ -bool -fragment_ready_to_send (struct fragment_master *f, struct buffer *buf, - const struct frame* frame) -{ - if (fragment_outgoing_defined (f)) - { - /* get fragment size, and determine if it is the last fragment */ - int size = f->outgoing_frag_size; - int last = false; - if (f->outgoing.len <= size) - { - size = f->outgoing.len; - last = true; - } - - /* initialize return buffer */ - *buf = f->outgoing_return; - ASSERT (buf_init (buf, FRAME_HEADROOM (frame))); - ASSERT (buf_copy_n (buf, &f->outgoing, size)); - - /* fragment flags differ based on whether or not we are sending the last fragment */ - fragment_prepend_flags (buf, - last ? FRAG_YES_LAST : FRAG_YES_NOTLAST, - f->outgoing_seq_id, - f->outgoing_frag_id++, - f->outgoing_frag_size); - - ASSERT (!last || !f->outgoing.len); /* outgoing buffer length should be zero after last fragment sent */ - - return true; - } - else - return false; -} - -static void -fragment_ttl_reap (struct fragment_master *f) -{ - int i; - for (i = 0; i < N_FRAG_BUF; ++i) - { - struct fragment *frag = &f->incoming.fragments[i]; - if (frag->defined && frag->timestamp + FRAG_TTL_SEC <= now) - { - msg (D_FRAG_ERRORS, "FRAG TTL expired i=%d", i); - frag->defined = false; - } - } -} - -/* called every FRAG_WAKEUP_INTERVAL seconds */ -void -fragment_wakeup (struct fragment_master *f, struct frame *frame) -{ - /* delete fragments with expired TTLs */ - fragment_ttl_reap (f); -} - -#else -static void dummy(void) {} -#endif |