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/*
* Copyright (c) 2017, Matias Fontanini
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <tins/tcp_ip/ack_tracker.h>
#ifdef TINS_HAVE_ACK_TRACKER
#include <limits>
#include <tins/tcp.h>
#include <tins/detail/sequence_number_helpers.h>
using std::vector;
using std::numeric_limits;
using boost::icl::interval_bounds;
using boost::icl::contains;
using Tins::Internals::seq_compare;
namespace Tins {
namespace TCPIP {
uint32_t interval_start(const AckedRange::interval_type& interval) {
if (interval.bounds() == interval_bounds::left_open()) {
return interval.lower() + 1;
}
else {
return interval.lower();
}
}
uint32_t interval_end(const AckedRange::interval_type& interval) {
if (interval.bounds() == interval_bounds::right_open()) {
return interval.upper() - 1;
}
else {
return interval.upper();
}
}
// AckedRange
AckedRange::AckedRange(uint32_t first, uint32_t last)
: first_(first), last_(last) {
}
AckedRange::interval_type AckedRange::next() {
uint32_t interval_first = first_;
// Regular case
if (first_ <= last_) {
first_ = last_ + 1;
return interval_type::closed(interval_first, last_);
}
else {
// Range wraps around
first_ = 0;
return interval_type::closed(interval_first, numeric_limits<uint32_t>::max());
}
}
bool AckedRange::has_next() const {
return seq_compare(first_, last_) <= 0;
}
uint32_t AckedRange::first() const {
return first_;
}
uint32_t AckedRange::last() const {
return last_;
}
// AckTracker
AckTracker::AckTracker()
: ack_number_(0), use_sack_(false) {
}
AckTracker::AckTracker(uint32_t initial_ack, bool use_sack)
: ack_number_(initial_ack), use_sack_(use_sack) {
}
void AckTracker::process_packet(const PDU& packet) {
const TCP* tcp = packet.find_pdu<TCP>();
if (!tcp) {
return;
}
if (seq_compare(tcp->ack_seq(), ack_number_) > 0) {
cleanup_sacked_intervals(ack_number_, tcp->ack_seq());
ack_number_ = tcp->ack_seq();
}
if (use_sack_) {
const TCP::option* sack_option = tcp->search_option(TCP::SACK);
if (sack_option) {
TCP::sack_type sack = sack_option->to<TCP::sack_type>();
process_sack(sack);
}
}
}
void AckTracker::process_sack(const vector<uint32_t>& sack) {
for (size_t i = 1; i < sack.size(); i += 2) {
// Left edge must be lower than right edge
if (seq_compare(sack[i - 1], sack[i]) < 0) {
AckedRange range(sack[i - 1], sack[i] - 1);
// If this range ends after our current ack number
if (seq_compare(range.last(), ack_number_) > 0) {
while (range.has_next()) {
AckedRange::interval_type next = range.next();
uint32_t start = interval_start(next);
if (seq_compare(start, ack_number_) <= 0) {
// If this interval starts before or at our ACK number
// then we need to update our ACK number to the end of
// this interval
ack_number_ = interval_end(next);
}
else {
// Otherwise, push the interval into the ACK set
acked_intervals_.insert(next);
}
}
}
}
}
}
void AckTracker::cleanup_sacked_intervals(uint32_t old_ack, uint32_t new_ack) {
AckedRange range(old_ack, new_ack);
while (range.has_next()) {
acked_intervals_.erase(range.next());
}
}
void AckTracker::use_sack() {
use_sack_ = true;
}
uint32_t AckTracker::ack_number() const {
return ack_number_;
}
const AckTracker::interval_set_type& AckTracker::acked_intervals() const {
return acked_intervals_;
}
bool AckTracker::is_segment_acked(uint32_t sequence_number, uint32_t length) const {
if (length == 0) {
return true;
}
AckedRange range(sequence_number, sequence_number + length - 1);
while (range.has_next()) {
AckedRange::interval_type interval = range.next();
const int comparison = seq_compare(interval_end(interval), ack_number_);
// Only check for SACKed intervals if the segment finishes after our ACK number
if (comparison >= 0 && !contains(acked_intervals_, interval)) {
return false;
}
}
return true;
}
} // TCPIP
} // Tins
#endif // TINS_HAVE_ACK_TRACKER
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