mirror of
https://github.com/xcat2/xNBA.git
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[ipv4] Generalise fragment reassembly mechanism
Generalise the concept of fragment reassembly to allow for code sharing between IPv4 and IPv6 protocols. Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
parent
ae0124cd40
commit
22a0c4475c
68
src/include/ipxe/fragment.h
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68
src/include/ipxe/fragment.h
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@ -0,0 +1,68 @@
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#ifndef _IPXE_FRAGMENT_H
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#define _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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FILE_LICENCE ( GPL2_OR_LATER );
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#include <stdint.h>
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#include <ipxe/list.h>
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#include <ipxe/iobuf.h>
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#include <ipxe/retry.h>
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/** Fragment reassembly timeout */
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#define FRAGMENT_TIMEOUT ( TICKS_PER_SEC / 2 )
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/** A fragment reassembly buffer */
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struct fragment {
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/* List of fragment reassembly buffers */
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struct list_head list;
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/** Reassembled packet */
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struct io_buffer *iobuf;
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/** Length of non-fragmentable portion of reassembled packet */
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size_t hdrlen;
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/** Reassembly timer */
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struct retry_timer timer;
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};
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/** A fragment reassembler */
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struct fragment_reassembler {
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/** List of fragment reassembly buffers */
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struct list_head list;
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/**
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* Check if fragment matches fragment reassembly buffer
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*
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* @v fragment Fragment reassembly buffer
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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 is_fragment Fragment matches this reassembly buffer
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*/
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int ( * is_fragment ) ( struct fragment *fragment,
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struct io_buffer *iobuf, size_t hdrlen );
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/**
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* Get fragment offset
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*
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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 offset Offset
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*/
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size_t ( * fragment_offset ) ( struct io_buffer *iobuf, size_t hdrlen );
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/**
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* Check if more fragments exist
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*
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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 more_frags More fragments exist
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*/
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int ( * more_fragments ) ( struct io_buffer *iobuf, size_t hdrlen );
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};
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extern struct io_buffer *
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fragment_reassemble ( struct fragment_reassembler *fragments,
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struct io_buffer *iobuf, size_t *hdrlen );
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#endif /* _IPXE_FRAGMENT_H */
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@ -70,18 +70,6 @@ struct ipv4_miniroute {
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struct in_addr gateway;
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};
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/* IPv4 fragment reassembly buffer */
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struct ipv4_fragment {
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/* List of fragment reassembly buffers */
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struct list_head list;
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/** Reassembled packet */
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struct io_buffer *iobuf;
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/** Current offset */
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size_t offset;
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/** Reassembly timer */
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struct retry_timer timer;
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};
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extern struct list_head ipv4_miniroutes;
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extern struct net_protocol ipv4_protocol __net_protocol;
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172
src/net/fragment.c
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172
src/net/fragment.c
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@ -0,0 +1,172 @@
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/*
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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/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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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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/* 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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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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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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free_iob ( iobuf );
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return NULL;
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}
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166
src/net/ipv4.c
166
src/net/ipv4.c
@ -14,7 +14,7 @@
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#include <ipxe/tcpip.h>
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#include <ipxe/dhcp.h>
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#include <ipxe/settings.h>
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#include <ipxe/timer.h>
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#include <ipxe/fragment.h>
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/** @file
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*
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@ -30,12 +30,6 @@ static uint8_t next_ident_high = 0;
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/** List of IPv4 miniroutes */
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struct list_head ipv4_miniroutes = LIST_HEAD_INIT ( ipv4_miniroutes );
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/** List of fragment reassembly buffers */
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static LIST_HEAD ( ipv4_fragments );
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/** Fragment reassembly timeout */
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#define IP_FRAG_TIMEOUT ( TICKS_PER_SEC / 2 )
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/**
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* Add IPv4 minirouting table entry
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*
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@ -133,131 +127,59 @@ static struct ipv4_miniroute * ipv4_route ( struct in_addr *dest ) {
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}
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/**
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* Expire fragment reassembly buffer
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* Check if IPv4 fragment matches 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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* @v fragment Fragment reassembly buffer
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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 is_fragment Fragment matches this reassembly buffer
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*/
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static void ipv4_fragment_expired ( struct retry_timer *timer,
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int fail __unused ) {
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struct ipv4_fragment *frag =
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container_of ( timer, struct ipv4_fragment, timer );
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struct iphdr *iphdr = frag->iobuf->data;
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static int ipv4_is_fragment ( struct fragment *fragment,
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struct io_buffer *iobuf,
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size_t hdrlen __unused ) {
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struct iphdr *frag_iphdr = fragment->iobuf->data;
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struct iphdr *iphdr = iobuf->data;
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DBGC ( iphdr->src, "IPv4 fragment %04x expired\n",
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ntohs ( iphdr->ident ) );
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free_iob ( frag->iobuf );
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list_del ( &frag->list );
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free ( frag );
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return ( ( iphdr->src.s_addr == frag_iphdr->src.s_addr ) &&
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( iphdr->ident == frag_iphdr->ident ) );
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}
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/**
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* Find matching fragment reassembly buffer
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*
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* @v iphdr IPv4 header
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* @ret frag Fragment reassembly buffer, or NULL
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*/
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static struct ipv4_fragment * ipv4_fragment ( struct iphdr *iphdr ) {
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struct ipv4_fragment *frag;
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struct iphdr *frag_iphdr;
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list_for_each_entry ( frag, &ipv4_fragments, list ) {
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frag_iphdr = frag->iobuf->data;
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if ( ( iphdr->src.s_addr == frag_iphdr->src.s_addr ) &&
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( iphdr->ident == frag_iphdr->ident ) ) {
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return frag;
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}
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}
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return NULL;
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}
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/**
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* Fragment reassembler
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* Get IPv4 fragment offset
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*
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* @v iobuf I/O buffer
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* @ret iobuf Reassembled packet, or NULL
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* @v hdrlen Length of non-fragmentable potion of I/O buffer
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* @ret offset Offset
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*/
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static struct io_buffer * ipv4_reassemble ( struct io_buffer *iobuf ) {
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static size_t ipv4_fragment_offset ( struct io_buffer *iobuf,
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size_t hdrlen __unused ) {
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struct iphdr *iphdr = iobuf->data;
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size_t offset = ( ( ntohs ( iphdr->frags ) & IP_MASK_OFFSET ) << 3 );
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unsigned int more_frags = ( iphdr->frags & htons ( IP_MASK_MOREFRAGS ));
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size_t hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
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struct ipv4_fragment *frag;
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size_t expected_offset;
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struct io_buffer *new_iobuf;
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/* Find matching fragment reassembly buffer, if any */
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frag = ipv4_fragment ( iphdr );
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/* Drop out-of-order fragments */
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expected_offset = ( frag ? frag->offset : 0 );
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if ( offset != expected_offset ) {
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DBGC ( iphdr->src, "IPv4 dropping out-of-sequence fragment "
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"%04x (%zd+%zd, expected %zd)\n",
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ntohs ( iphdr->ident ), offset,
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( iob_len ( iobuf ) - hdrlen ), 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 ( frag == NULL ) {
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/* Create new fragment reassembly buffer */
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frag = zalloc ( sizeof ( *frag ) );
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if ( ! frag )
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goto drop;
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list_add ( &frag->list, &ipv4_fragments );
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frag->iobuf = iobuf;
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frag->offset = ( iob_len ( iobuf ) - hdrlen );
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timer_init ( &frag->timer, ipv4_fragment_expired, NULL );
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} else {
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/* Extend reassembly buffer */
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iob_pull ( iobuf, hdrlen );
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new_iobuf = alloc_iob ( iob_len ( frag->iobuf ) +
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iob_len ( iobuf ) );
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if ( ! new_iobuf ) {
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DBGC ( iphdr->src, "IPv4 could not extend reassembly "
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"buffer to %zd bytes\n",
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iob_len ( frag->iobuf ) + iob_len ( iobuf ) );
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goto drop;
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}
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memcpy ( iob_put ( new_iobuf, iob_len ( frag->iobuf ) ),
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frag->iobuf->data, iob_len ( frag->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 ( frag->iobuf );
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frag->iobuf = new_iobuf;
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frag->offset += iob_len ( iobuf );
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free_iob ( iobuf );
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iphdr = frag->iobuf->data;
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iphdr->len = ntohs ( iob_len ( frag->iobuf ) );
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/* Stop fragment reassembly timer */
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stop_timer ( &frag->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 = frag->iobuf;
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list_del ( &frag->list );
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free ( frag );
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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 ( &frag->timer, IP_FRAG_TIMEOUT );
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return NULL;
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drop:
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free_iob ( iobuf );
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return NULL;
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return ( ( ntohs ( iphdr->frags ) & IP_MASK_OFFSET ) << 3 );
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}
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/**
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* Check if more fragments exist
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*
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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 more_frags More fragments exist
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*/
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static int ipv4_more_fragments ( struct io_buffer *iobuf,
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size_t hdrlen __unused ) {
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struct iphdr *iphdr = iobuf->data;
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return ( iphdr->frags & htons ( IP_MASK_MOREFRAGS ) );
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}
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/** IPv4 fragment reassembler */
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static struct fragment_reassembler ipv4_reassembler = {
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.list = LIST_HEAD_INIT ( ipv4_reassembler.list ),
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.is_fragment = ipv4_is_fragment,
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.fragment_offset = ipv4_fragment_offset,
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.more_fragments = ipv4_more_fragments,
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};
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/**
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* Add IPv4 pseudo-header checksum to existing checksum
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*
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@ -526,14 +448,14 @@ static int ipv4_rx ( struct io_buffer *iobuf,
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/* Perform fragment reassembly if applicable */
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if ( iphdr->frags & htons ( IP_MASK_OFFSET | IP_MASK_MOREFRAGS ) ) {
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/* Pass the fragment to ipv4_reassemble() which returns
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/* Pass the fragment to fragment_reassemble() which returns
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* either a fully reassembled I/O buffer or NULL.
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*/
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iobuf = ipv4_reassemble ( iobuf );
|
||||
iobuf = fragment_reassemble ( &ipv4_reassembler, iobuf,
|
||||
&hdrlen );
|
||||
if ( ! iobuf )
|
||||
return 0;
|
||||
iphdr = iobuf->data;
|
||||
hdrlen = ( ( iphdr->verhdrlen & IP_MASK_HLEN ) * 4 );
|
||||
}
|
||||
|
||||
/* Construct socket addresses, calculate pseudo-header
|
||||
|
||||
Loading…
Reference in New Issue
Block a user