encryptedPacket.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 anytun.org <satp@wirdorange.org>
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License version 2
  18  *  as published by the Free Software Foundation.
  19  *
  20  *  This program is distributed in the hope that it will be useful,
  21  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  *  GNU General Public License for more details.
  24  *
  25  *  You should have received a copy of the GNU General Public License
  26  *  along with this program (see the file COPYING included with this
  27  *  distribution); if not, write to the Free Software Foundation, Inc.,
  28  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  29  */
  30
  31 #include <stdexcept>
  32 #include <iostream>
  33 #include <arpa/inet.h>
  34 #include <cstdio>       // for std::memcpy
  35
  36 #include "encryptedPacket.h"
  37 #include "datatypes.h"
  38 #include "log.h"
  39
  40 EncryptedPacket::EncryptedPacket(u_int32_t payload_length, bool allow_realloc)
  41   : Buffer(payload_length + sizeof(struct HeaderStruct), allow_realloc)
  42 {
  43   header_ = reinterpret_cast<struct HeaderStruct*>(buf_);
  44   payload_ = buf_ + sizeof(struct HeaderStruct);
  45   auth_tag_ = NULL;
  46   if(header_)
  47   {
  48     header_->seq_nr = 0;
  49     header_->sender_id = 0;
  50     header_->mux = 0;
  51   }
  52 }
  53
  54 seq_nr_t EncryptedPacket::getSeqNr() const
  55 {
  56   if(header_)
  57     return SEQ_NR_T_NTOH(header_->seq_nr);
  58
  59   return 0;
  60 }
  61
  62 sender_id_t EncryptedPacket::getSenderId() const
  63 {
  64   if(header_)
  65     return SENDER_ID_T_NTOH(header_->sender_id);
  66
  67   return 0;
  68 }
  69
  70 mux_t EncryptedPacket::getMux() const
  71 {
  72   if(header_)
  73     return MUX_T_NTOH(header_->mux);
  74
  75   return 0;
  76 }
  77
  78 void EncryptedPacket::setSeqNr(seq_nr_t seq_nr)
  79 {
  80   if(header_)
  81     header_->seq_nr = SEQ_NR_T_HTON(seq_nr);
  82 }
  83
  84 void EncryptedPacket::setSenderId(sender_id_t sender_id)
  85 {
  86   if(header_)
  87     header_->sender_id = SENDER_ID_T_HTON(sender_id);
  88 }
  89
  90 void EncryptedPacket::setMux(mux_t mux)
  91 {
  92   if(header_)
  93     header_->mux = MUX_T_HTON(mux);
  94 }
  95
  96 void EncryptedPacket::setHeader(seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
  97 {
  98   if(!header_)
  99     return;
 100
 101   header_->seq_nr = SEQ_NR_T_HTON(seq_nr);
 102   header_->sender_id = SENDER_ID_T_HTON(sender_id);
 103   header_->mux = MUX_T_HTON(mux);
 104 }
 105
 106 u_int32_t EncryptedPacket::getPayloadLength() const
 107 {
 108   if(!payload_)
 109     return 0;
 110
 111   if(!auth_tag_)
 112     return (length_ > sizeof(struct HeaderStruct)) ? (length_ - sizeof(struct HeaderStruct)) : 0;
 113
 114   return (length_ > (sizeof(struct HeaderStruct) + AUTHTAG_SIZE)) ? (length_ - sizeof(struct HeaderStruct) - AUTHTAG_SIZE) : 0;
 115 }
 116
 117 void EncryptedPacket::setPayloadLength(u_int32_t payload_length)
 118 {
 119   Buffer::setLength(payload_length + sizeof(struct HeaderStruct));
 120       // depending on allow_realloc buf_ may point to another address
 121       // therefore in this case reinit() gets called by Buffer::setLength()
 122 }
 123
 124 void EncryptedPacket::reinit()
 125 {
 126   header_ = reinterpret_cast<struct HeaderStruct*>(buf_);
 127   payload_ = buf_ + sizeof(struct HeaderStruct);
 128
 129   if(length_ <= (sizeof(struct HeaderStruct)))
 130     payload_ = NULL;
 131
 132   if(length_ < (sizeof(struct HeaderStruct))) {
 133     header_ = NULL;
 134     throw std::runtime_error("packet can't be initialized, buffer is too small");
 135   }
 136
 137   if(auth_tag_)
 138   {
 139     if(length_ < (sizeof(struct HeaderStruct) + AUTHTAG_SIZE)) {
 140       auth_tag_ = NULL;
 141       throw std::runtime_error("auth-tag can't be enabled, buffer is too small");
 142     }
 143     auth_tag_ = buf_ + length_ - AUTHTAG_SIZE;
 144   }
 145 }
 146
 147 u_int8_t* EncryptedPacket::getPayload()
 148 {
 149   return payload_;
 150 }
 151
 152 u_int8_t* EncryptedPacket::getAuthenticatedPortion()
 153 {
 154   return buf_;
 155 }
 156
 157 u_int32_t EncryptedPacket::getAuthenticatedPortionLength()
 158 {
 159   if(!buf_)
 160     return 0;
 161
 162   if(!auth_tag_)
 163     return length_;
 164
 165   return (length_ > AUTHTAG_SIZE) ? (length_ - AUTHTAG_SIZE) : 0;
 166 }
 167
 168 void EncryptedPacket::withAuthTag(bool b)
 169 {
 170   if((b && auth_tag_) || (!b && !auth_tag_))
 171     return;
 172
 173   if(b)
 174   {
 175     if(length_ < (sizeof(struct HeaderStruct) + AUTHTAG_SIZE))
 176       throw std::runtime_error("auth-tag can't be enabled, buffer is too small");
 177
 178     auth_tag_ = buf_ + length_ - AUTHTAG_SIZE;
 179   }
 180   else
 181     auth_tag_ = NULL;
 182 }
 183
 184 void EncryptedPacket::addAuthTag()
 185 {
 186   if(auth_tag_)
 187     return;
 188
 189   auth_tag_ = buf_; // will be set to the correct value @ reinit
 190   setLength(length_ + AUTHTAG_SIZE);
 191   if(auth_tag_ == buf_) // reinit was not called by setLength
 192     reinit();
 193 }
 194
 195 void EncryptedPacket::removeAuthTag()
 196 {
 197   if(!auth_tag_)
 198     return;
 199
 200   auth_tag_ = NULL;
 201   setLength(length_ - AUTHTAG_SIZE);
 202 }
 203
 204 u_int8_t* EncryptedPacket::getAuthTag()
 205 {
 206   return auth_tag_;
 207 }
 208
 209 u_int32_t EncryptedPacket::getAuthTagLength()
 210 {
 211   if(auth_tag_)
 212     return AUTHTAG_SIZE;
 213
 214   return 0;
 215 }