11963c4f5f
Signed-off-by: Michael Brown <mcb30@ipxe.org>
181 lines
5.3 KiB
C
181 lines
5.3 KiB
C
/*
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* Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ipxe/retry.h>
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#include <ipxe/timer.h>
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#include <ipxe/ipstat.h>
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#include <ipxe/fragment.h>
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/** @file
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*
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* Fragment reassembly
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*
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*/
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/**
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* Expire fragment reassembly buffer
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*
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* @v timer Retry timer
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* @v fail Failure indicator
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*/
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static void fragment_expired ( struct retry_timer *timer, int fail __unused ) {
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struct fragment *fragment =
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container_of ( timer, struct fragment, timer );
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DBGC ( fragment, "FRAG %p expired\n", fragment );
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free_iob ( fragment->iobuf );
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list_del ( &fragment->list );
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fragment->fragments->stats->reasm_fails++;
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free ( fragment );
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}
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/**
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* Find fragment reassembly buffer
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*
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* @v fragments Fragment reassembler
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* @v iobuf I/O buffer
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* @v hdrlen Length of non-fragmentable potion of I/O buffer
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* @ret fragment Fragment reassembly buffer, or NULL if not found
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*/
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static struct fragment * fragment_find ( struct fragment_reassembler *fragments,
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struct io_buffer *iobuf,
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size_t hdrlen ) {
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struct fragment *fragment;
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list_for_each_entry ( fragment, &fragments->list, list ) {
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if ( fragments->is_fragment ( fragment, iobuf, hdrlen ) )
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return fragment;
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}
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return NULL;
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}
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/**
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* Reassemble packet
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*
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* @v fragments Fragment reassembler
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* @v iobuf I/O buffer
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* @v hdrlen Length of non-fragmentable potion of I/O buffer
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* @ret iobuf Reassembled packet, or NULL
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*
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* This function takes ownership of the I/O buffer. Note that the
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* length of the non-fragmentable portion may be modified.
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*/
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struct io_buffer * fragment_reassemble ( struct fragment_reassembler *fragments,
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struct io_buffer *iobuf,
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size_t *hdrlen ) {
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struct fragment *fragment;
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struct io_buffer *new_iobuf;
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size_t new_len;
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size_t offset;
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size_t expected_offset;
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int more_frags;
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/* Update statistics */
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fragments->stats->reasm_reqds++;
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/* Find matching fragment reassembly buffer, if any */
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fragment = fragment_find ( fragments, iobuf, *hdrlen );
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/* Drop out-of-order fragments */
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offset = fragments->fragment_offset ( iobuf, *hdrlen );
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expected_offset = ( fragment ? ( iob_len ( fragment->iobuf ) -
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fragment->hdrlen ) : 0 );
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if ( offset != expected_offset ) {
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DBGC ( fragment, "FRAG %p dropping out-of-sequence fragment "
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"[%zd,%zd), expected [%zd,...)\n", fragment, offset,
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( offset + iob_len ( iobuf ) - *hdrlen ),
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expected_offset );
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goto drop;
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}
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/* Create or extend fragment reassembly buffer as applicable */
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if ( ! fragment ) {
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/* Create new fragment reassembly buffer */
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fragment = zalloc ( sizeof ( *fragment ) );
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if ( ! fragment )
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goto drop;
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list_add ( &fragment->list, &fragments->list );
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fragment->iobuf = iobuf;
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fragment->hdrlen = *hdrlen;
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timer_init ( &fragment->timer, fragment_expired, NULL );
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fragment->fragments = fragments;
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DBGC ( fragment, "FRAG %p [0,%zd)\n", fragment,
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( iob_len ( iobuf ) - *hdrlen ) );
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} else {
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/* Check if this is the final fragment */
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more_frags = fragments->more_fragments ( iobuf, *hdrlen );
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DBGC ( fragment, "FRAG %p [%zd,%zd)%s\n", fragment,
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offset, ( offset + iob_len ( iobuf ) - *hdrlen ),
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( more_frags ? "" : " complete" ) );
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/* Extend fragment reassembly buffer. Preserve I/O
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* buffer headroom to allow for code which modifies
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* and resends the buffer (e.g. ICMP echo responses).
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*/
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iob_pull ( iobuf, *hdrlen );
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new_len = ( iob_headroom ( fragment->iobuf ) +
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iob_len ( fragment->iobuf ) + iob_len ( iobuf ) );
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new_iobuf = alloc_iob ( new_len );
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if ( ! new_iobuf ) {
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DBGC ( fragment, "FRAG %p could not extend reassembly "
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"buffer to %zd bytes\n", fragment, new_len );
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goto drop;
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}
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iob_reserve ( new_iobuf, iob_headroom ( fragment->iobuf ) );
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memcpy ( iob_put ( new_iobuf, iob_len ( fragment->iobuf ) ),
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fragment->iobuf->data, iob_len ( fragment->iobuf ) );
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memcpy ( iob_put ( new_iobuf, iob_len ( iobuf ) ),
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iobuf->data, iob_len ( iobuf ) );
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free_iob ( fragment->iobuf );
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fragment->iobuf = new_iobuf;
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free_iob ( iobuf );
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/* Stop fragment reassembly timer */
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stop_timer ( &fragment->timer );
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/* If this is the final fragment, return it */
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if ( ! more_frags ) {
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iobuf = fragment->iobuf;
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*hdrlen = fragment->hdrlen;
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list_del ( &fragment->list );
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free ( fragment );
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fragments->stats->reasm_oks++;
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return iobuf;
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}
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}
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/* (Re)start fragment reassembly timer */
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start_timer_fixed ( &fragment->timer, FRAGMENT_TIMEOUT );
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return NULL;
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drop:
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fragments->stats->reasm_fails++;
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free_iob ( iobuf );
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return NULL;
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}
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