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/* Copyright (C) 2007-2016 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program 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
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Victor Julien <victor@inliniac.net>
*
* Functions for the "inline mode" of the stream engine.
*/
#include "suricata-common.h"
#include "decode.h"
#include "stream-tcp-private.h"
#include "stream-tcp-inline.h"
#include "util-memcmp.h"
#include "util-print.h"
#include "util-validate.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
/**
* \brief Compare the shared data portion of two segments
*
* If no data is shared, 0 will be returned.
*
* \param seg1 first segment
* \param seg2 second segment
*
* \retval 0 shared data is the same (or no data is shared)
* \retval 1 shared data is different
*/
int StreamTcpInlineSegmentCompare(const TcpStream *stream,
const Packet *p, const TcpSegment *seg)
{
SCEnter();
if (p == NULL || seg == NULL) {
SCReturnInt(0);
}
DEBUG_VALIDATE_BUG_ON(SEQ_LEQ(seg->seq + TCP_SEG_LEN(seg), stream->base_seq));
const uint8_t *seg_data;
uint32_t seg_datalen;
StreamingBufferSegmentGetData(&stream->sb, &seg->sbseg, &seg_data, &seg_datalen);
if (seg_data == NULL || seg_datalen == 0)
SCReturnInt(0);
const uint32_t pkt_seq = TCP_GET_SEQ(p);
if (SEQ_EQ(pkt_seq, seg->seq) && p->payload_len == seg_datalen) {
int r = SCMemcmp(p->payload, seg_data, seg_datalen);
SCReturnInt(r);
} else if (SEQ_GT(pkt_seq, (seg->seq + seg_datalen))) {
SCReturnInt(0);
} else if (SEQ_GT(seg->seq, (pkt_seq + p->payload_len))) {
SCReturnInt(0);
} else {
SCLogDebug("p %u (%u), seg2 %u (%u)", pkt_seq,
p->payload_len, seg->seq, seg_datalen);
uint32_t seg_seq = seg->seq;
if (SEQ_LT(seg_seq, stream->base_seq)) {
seg_seq = stream->base_seq;
}
uint32_t pkt_end = pkt_seq + p->payload_len;
uint32_t seg_end = seg_seq + seg_datalen;
SCLogDebug("pkt_end %u, seg_end %u", pkt_end, seg_end);
/* get the minimal seg*_end */
uint32_t end = SEQ_MIN(seg_end, pkt_end);
/* and the max seq */
uint32_t seq = SEQ_MAX(pkt_seq, seg_seq);
seq = SEQ_MAX(seq, stream->base_seq);
SCLogDebug("seq %u, end %u", seq, end);
uint32_t pkt_off = seq - pkt_seq;
uint32_t seg_off = seq - seg_seq;
SCLogDebug("pkt_off %u, seg_off %u", pkt_off, seg_off);
uint32_t range = end - seq;
SCLogDebug("range %u", range);
BUG_ON(range > 65536);
if (range) {
int r = SCMemcmp(p->payload + pkt_off, seg_data + seg_off, range);
SCReturnInt(r);
}
SCReturnInt(0);
}
}
/**
* \brief Replace (part of) the payload portion of a packet by the data
* in a TCP segment
*
* \param p Packet
* \param seg TCP segment
*
* \todo What about reassembled fragments?
* \todo What about unwrapped tunnel packets?
*/
void StreamTcpInlineSegmentReplacePacket(const TcpStream *stream,
Packet *p, const TcpSegment *seg)
{
SCEnter();
uint32_t pseq = TCP_GET_SEQ(p);
uint32_t tseq = seg->seq;
/* check if segment is within the packet */
if (tseq + TCP_SEG_LEN(seg) < pseq) {
SCReturn;
} else if (pseq + p->payload_len < tseq) {
SCReturn;
}
const uint8_t *seg_data;
uint32_t seg_datalen;
StreamingBufferSegmentGetData(&stream->sb, &seg->sbseg, &seg_data, &seg_datalen);
uint32_t pend = pseq + p->payload_len;
uint32_t tend = tseq + seg_datalen;
SCLogDebug("pend %u, tend %u", pend, tend);
/* get the minimal seg*_end */
uint32_t end = (SEQ_GT(pend, tend)) ? tend : pend;
/* and the max seq */
uint32_t seq = (SEQ_LT(pseq, tseq)) ? tseq : pseq;
SCLogDebug("seq %u, end %u", seq, end);
uint32_t poff = seq - pseq;
uint32_t toff = seq - tseq;
SCLogDebug("poff %u, toff %u", poff, toff);
uint32_t range = end - seq;
SCLogDebug("range %u", range);
BUG_ON(range > 65536);
if (range) {
/* update the packets payload. As payload is a ptr to either
* p->pkt or p->ext_pkt that is updated as well */
memcpy(p->payload+poff, seg_data+toff, range);
/* flag as modified so we can reinject / replace after
* recalculating the checksum */
p->flags |= PKT_STREAM_MODIFIED;
}
}
#ifdef UNITTESTS
#include "tests/stream-tcp-inline.c"
#endif
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