--- /dev/null
+/*
+ * Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ipxe/retry.h>
+#include <ipxe/timer.h>
+#include <ipxe/ipstat.h>
+#include <ipxe/fragment.h>
+
+/** @file
+ *
+ * Fragment reassembly
+ *
+ */
+
+/**
+ * Expire fragment reassembly buffer
+ *
+ * @v timer Retry timer
+ * @v fail Failure indicator
+ */
+static void fragment_expired ( struct retry_timer *timer, int fail __unused ) {
+ struct fragment *fragment =
+ container_of ( timer, struct fragment, timer );
+
+ DBGC ( fragment, "FRAG %p expired\n", fragment );
+ free_iob ( fragment->iobuf );
+ list_del ( &fragment->list );
+ fragment->fragments->stats->reasm_fails++;
+ free ( fragment );
+}
+
+/**
+ * Find fragment reassembly buffer
+ *
+ * @v fragments Fragment reassembler
+ * @v iobuf I/O buffer
+ * @v hdrlen Length of non-fragmentable potion of I/O buffer
+ * @ret fragment Fragment reassembly buffer, or NULL if not found
+ */
+static struct fragment * fragment_find ( struct fragment_reassembler *fragments,
+ struct io_buffer *iobuf,
+ size_t hdrlen ) {
+ struct fragment *fragment;
+
+ list_for_each_entry ( fragment, &fragments->list, list ) {
+ if ( fragments->is_fragment ( fragment, iobuf, hdrlen ) )
+ return fragment;
+ }
+ return NULL;
+}
+
+/**
+ * Reassemble packet
+ *
+ * @v fragments Fragment reassembler
+ * @v iobuf I/O buffer
+ * @v hdrlen Length of non-fragmentable potion of I/O buffer
+ * @ret iobuf Reassembled packet, or NULL
+ *
+ * This function takes ownership of the I/O buffer. Note that the
+ * length of the non-fragmentable portion may be modified.
+ */
+struct io_buffer * fragment_reassemble ( struct fragment_reassembler *fragments,
+ struct io_buffer *iobuf,
+ size_t *hdrlen ) {
+ struct fragment *fragment;
+ struct io_buffer *new_iobuf;
+ size_t new_len;
+ size_t offset;
+ size_t expected_offset;
+ int more_frags;
+
+ /* Update statistics */
+ fragments->stats->reasm_reqds++;
+
+ /* Find matching fragment reassembly buffer, if any */
+ fragment = fragment_find ( fragments, iobuf, *hdrlen );
+
+ /* Drop out-of-order fragments */
+ offset = fragments->fragment_offset ( iobuf, *hdrlen );
+ expected_offset = ( fragment ? ( iob_len ( fragment->iobuf ) -
+ fragment->hdrlen ) : 0 );
+ if ( offset != expected_offset ) {
+ DBGC ( fragment, "FRAG %p dropping out-of-sequence fragment "
+ "[%zd,%zd), expected [%zd,...)\n", fragment, offset,
+ ( offset + iob_len ( iobuf ) - *hdrlen ),
+ expected_offset );
+ goto drop;
+ }
+
+ /* Create or extend fragment reassembly buffer as applicable */
+ if ( ! fragment ) {
+
+ /* Create new fragment reassembly buffer */
+ fragment = zalloc ( sizeof ( *fragment ) );
+ if ( ! fragment )
+ goto drop;
+ list_add ( &fragment->list, &fragments->list );
+ fragment->iobuf = iobuf;
+ fragment->hdrlen = *hdrlen;
+ timer_init ( &fragment->timer, fragment_expired, NULL );
+ fragment->fragments = fragments;
+ DBGC ( fragment, "FRAG %p [0,%zd)\n", fragment,
+ ( iob_len ( iobuf ) - *hdrlen ) );
+
+ } else {
+
+ /* Check if this is the final fragment */
+ more_frags = fragments->more_fragments ( iobuf, *hdrlen );
+ DBGC ( fragment, "FRAG %p [%zd,%zd)%s\n", fragment,
+ offset, ( offset + iob_len ( iobuf ) - *hdrlen ),
+ ( more_frags ? "" : " complete" ) );
+
+ /* Extend fragment reassembly buffer. Preserve I/O
+ * buffer headroom to allow for code which modifies
+ * and resends the buffer (e.g. ICMP echo responses).
+ */
+ iob_pull ( iobuf, *hdrlen );
+ new_len = ( iob_headroom ( fragment->iobuf ) +
+ iob_len ( fragment->iobuf ) + iob_len ( iobuf ) );
+ new_iobuf = alloc_iob ( new_len );
+ if ( ! new_iobuf ) {
+ DBGC ( fragment, "FRAG %p could not extend reassembly "
+ "buffer to %zd bytes\n", fragment, new_len );
+ goto drop;
+ }
+ iob_reserve ( new_iobuf, iob_headroom ( fragment->iobuf ) );
+ memcpy ( iob_put ( new_iobuf, iob_len ( fragment->iobuf ) ),
+ fragment->iobuf->data, iob_len ( fragment->iobuf ) );
+ memcpy ( iob_put ( new_iobuf, iob_len ( iobuf ) ),
+ iobuf->data, iob_len ( iobuf ) );
+ free_iob ( fragment->iobuf );
+ fragment->iobuf = new_iobuf;
+ free_iob ( iobuf );
+
+ /* Stop fragment reassembly timer */
+ stop_timer ( &fragment->timer );
+
+ /* If this is the final fragment, return it */
+ if ( ! more_frags ) {
+ iobuf = fragment->iobuf;
+ *hdrlen = fragment->hdrlen;
+ list_del ( &fragment->list );
+ free ( fragment );
+ fragments->stats->reasm_oks++;
+ return iobuf;
+ }
+ }
+
+ /* (Re)start fragment reassembly timer */
+ start_timer_fixed ( &fragment->timer, FRAGMENT_TIMEOUT );
+
+ return NULL;
+
+ drop:
+ fragments->stats->reasm_fails++;
+ free_iob ( iobuf );
+ return NULL;
+}
Code Review / kvmfornfv.git / blobdiff