src/seqWindow.cpp

   1 /*
   2  *  anytun
   3  *
   4  *  The secure anycast tunneling protocol (satp) defines a protocol used
   5  *  for communication between any combination of unicast and anycast
   6  *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
   7  *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
   8  *  ethernet, ip, arp ...). satp directly includes cryptography and
   9  *  message authentication based on the methodes used by SRTP.  It is
  10  *  intended to deliver a generic, scaleable and secure solution for
  11  *  tunneling and relaying of packets of any protocol.
  12  *
  13  *
  14  *  Copyright (C) 2007-2008 Othmar Gsenger, Erwin Nindl,
  15  *                          Christian Pointner <satp@wirdorange.org>
  16  *
  17  *  This file is part of Anytun.
  18  *
  19  *  Anytun is free software: you can redistribute it and/or modify
  20  *  it under the terms of the GNU General Public License version 3 as
  21  *  published by the Free Software Foundation.
  22  *
  23  *  Anytun is distributed in the hope that it will be useful,
  24  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  25  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26  *  GNU General Public License for more details.
  27  *
  28  *  You should have received a copy of the GNU General Public License
  29  *  along with anytun.  If not, see <http://www.gnu.org/licenses/>.
  30  */
  31
  32 #include "threadUtils.hpp"
  33 #include "datatypes.h"
  34
  35 #include "seqWindow.h"
  36
  37 SeqWindowElement::SeqWindowElement()
  38 {
  39   window_ = NULL;
  40   pos_ = 0;
  41   max_ = 0;
  42 }
  43
  44 SeqWindowElement::~SeqWindowElement()
  45 {
  46   if(window_)
  47     delete[] window_;
  48 }
  49
  50 void SeqWindowElement::init(window_size_t w, seq_nr_t m)
  51 {
  52   if(window_)
  53     delete[] window_;
  54   window_ = new u_int8_t[w];
  55   memset(window_, 0, w);
  56   pos_ = 0;
  57   max_ = m;
  58   window_[pos_] = 1;
  59 }
  60
  61 SeqWindow::SeqWindow(window_size_t w) : window_size_(w)
  62 {
  63 }
  64
  65 SeqWindow::~SeqWindow()
  66 {
  67 }
  68
  69 bool SeqWindow::checkAndAdd(sender_id_t sender, seq_nr_t seq_nr)
  70 {
  71   Lock lock(mutex_);
  72   if (!window_size_)
  73     return false;
  74
  75   SenderMap::iterator s = sender_.find(sender);
  76   if(s == sender_.end()) {
  77     sender_[sender].init(window_size_, seq_nr);
  78     return false;
  79   }
  80
  81   int shifted = 0;
  82   if(s->second.max_ < window_size_) {
  83     s->second.max_ += SEQ_NR_MAX/2;
  84     seq_nr += SEQ_NR_MAX/2;
  85     shifted = 1;
  86   }
  87   else if(s->second.max_ > (SEQ_NR_MAX - window_size_)) {
  88     s->second.max_ -= SEQ_NR_MAX/2;
  89     seq_nr -= SEQ_NR_MAX/2;
  90     shifted = 2;
  91   }
  92
  93   seq_nr_t min = s->second.max_ - window_size_ + 1;
  94   if(seq_nr < min || seq_nr == s->second.max_) {
  95     if(shifted == 1)
  96       s->second.max_ -= SEQ_NR_MAX/2;
  97     else if(shifted == 2)
  98       s->second.max_ += SEQ_NR_MAX/2;
  99     return true;
 100   }
 101
 102   if(seq_nr > s->second.max_) {
 103     seq_nr_t diff = seq_nr - s->second.max_;
 104     if(diff >= window_size_)
 105       diff = window_size_;
 106
 107     window_size_t new_pos = s->second.pos_ + diff;
 108
 109     if(new_pos >= window_size_) {
 110       new_pos -= window_size_;
 111
 112       if(s->second.pos_ < window_size_ - 1)
 113         memset(&(s->second.window_[s->second.pos_ + 1]), 0, window_size_ - s->second.pos_ - 1);
 114
 115       memset(s->second.window_, 0, new_pos);
 116     }
 117     else {
 118       memset(&(s->second.window_[s->second.pos_ + 1]), 0, diff);
 119     }
 120     s->second.pos_ = new_pos;
 121     s->second.window_[s->second.pos_] = 1;
 122     s->second.max_ = seq_nr;
 123
 124     if(shifted == 1)
 125       s->second.max_ -= SEQ_NR_MAX/2;
 126     else if(shifted == 2)
 127       s->second.max_ += SEQ_NR_MAX/2;
 128
 129     return false;
 130   }
 131
 132   seq_nr_t diff = s->second.max_ - seq_nr;
 133   window_size_t pos = diff > s->second.pos_ ? s->second.pos_ + window_size_ : s->second.pos_;
 134   pos -= diff;
 135
 136   if(shifted == 1)
 137     s->second.max_ -= SEQ_NR_MAX/2;
 138   else if(shifted == 2)
 139     s->second.max_ += SEQ_NR_MAX/2;
 140
 141   int ret = s->second.window_[pos];
 142   s->second.window_[pos] = 1;
 143
 144   if(ret)
 145     return true;
 146
 147   return false;
 148 }
 149
 150 void SeqWindow::clear(sender_id_t sender)
 151 {
 152   Lock lock(mutex_);
 153   sender_.erase(sender);
 154 }
 155
 156 void SeqWindow::clear()
 157 {
 158   Lock lock(mutex_);
 159   sender_.clear();
 160 }