src/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) 2007-2008 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 <stdexcept>
  33 #include <iostream>
  34 #include <cstdio>       // for std::memcpy
  35
  36 #include "encryptedPacket.h"
  37 #include "endian.h"
  38 #include "datatypes.h"
  39 #include "log.h"
  40
  41 EncryptedPacket::EncryptedPacket(u_int32_t payload_length, bool allow_realloc)
  42   : Buffer(payload_length + sizeof(struct HeaderStruct), allow_realloc)
  43 {
  44   header_ = reinterpret_cast<struct HeaderStruct*>(buf_);
  45   payload_ = buf_ + sizeof(struct HeaderStruct);
  46   auth_tag_ = NULL;
  47   if(header_)
  48   {
  49     header_->seq_nr = 0;
  50     header_->sender_id = 0;
  51     header_->mux = 0;
  52   }
  53 }
  54
  55 u_int32_t EncryptedPacket::getHeaderLength()
  56 {
  57   return sizeof(struct HeaderStruct);
  58 }
  59
  60 seq_nr_t EncryptedPacket::getSeqNr() const
  61 {
  62   if(header_)
  63     return SEQ_NR_T_NTOH(header_->seq_nr);
  64
  65   return 0;
  66 }
  67
  68 sender_id_t EncryptedPacket::getSenderId() const
  69 {
  70   if(header_)
  71     return SENDER_ID_T_NTOH(header_->sender_id);
  72
  73   return 0;
  74 }
  75
  76 mux_t EncryptedPacket::getMux() const
  77 {
  78   if(header_)
  79     return MUX_T_NTOH(header_->mux);
  80
  81   return 0;
  82 }
  83
  84 void EncryptedPacket::setSeqNr(seq_nr_t seq_nr)
  85 {
  86   if(header_)
  87     header_->seq_nr = SEQ_NR_T_HTON(seq_nr);
  88 }
  89
  90 void EncryptedPacket::setSenderId(sender_id_t sender_id)
  91 {
  92   if(header_)
  93     header_->sender_id = SENDER_ID_T_HTON(sender_id);
  94 }
  95
  96 void EncryptedPacket::setMux(mux_t mux)
  97 {
  98   if(header_)
  99     header_->mux = MUX_T_HTON(mux);
 100 }
 101
 102 void EncryptedPacket::setHeader(seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
 103 {
 104   if(!header_)
 105     return;
 106
 107   header_->seq_nr = SEQ_NR_T_HTON(seq_nr);
 108   header_->sender_id = SENDER_ID_T_HTON(sender_id);
 109   header_->mux = MUX_T_HTON(mux);
 110 }
 111
 112 u_int32_t EncryptedPacket::getPayloadLength() const
 113 {
 114   if(!payload_)
 115     return 0;
 116
 117   if(!auth_tag_)
 118     return (length_ > sizeof(struct HeaderStruct)) ? (length_ - sizeof(struct HeaderStruct)) : 0;
 119
 120   return (length_ > (sizeof(struct HeaderStruct) + AUTHTAG_SIZE)) ? (length_ - sizeof(struct HeaderStruct) - AUTHTAG_SIZE) : 0;
 121 }
 122
 123 void EncryptedPacket::setPayloadLength(u_int32_t payload_length)
 124 {
 125   Buffer::setLength(payload_length + sizeof(struct HeaderStruct));
 126       // depending on allow_realloc buf_ may point to another address
 127       // therefore in this case reinit() gets called by Buffer::setLength()
 128 }
 129
 130 void EncryptedPacket::reinit()
 131 {
 132   header_ = reinterpret_cast<struct HeaderStruct*>(buf_);
 133   payload_ = buf_ + sizeof(struct HeaderStruct);
 134
 135   if(length_ <= (sizeof(struct HeaderStruct)))
 136     payload_ = NULL;
 137
 138   if(length_ < (sizeof(struct HeaderStruct))) {
 139     header_ = NULL;
 140     throw std::runtime_error("packet can't be initialized, buffer is too small");
 141   }
 142
 143   if(auth_tag_)
 144   {
 145     if(length_ < (sizeof(struct HeaderStruct) + AUTHTAG_SIZE)) {
 146       auth_tag_ = NULL;
 147       throw std::runtime_error("auth-tag can't be enabled, buffer is too small");
 148     }
 149     auth_tag_ = buf_ + length_ - AUTHTAG_SIZE;
 150   }
 151 }
 152
 153 u_int8_t* EncryptedPacket::getPayload()
 154 {
 155   return payload_;
 156 }
 157
 158 u_int8_t* EncryptedPacket::getAuthenticatedPortion()
 159 {
 160   return buf_;
 161 }
 162
 163 u_int32_t EncryptedPacket::getAuthenticatedPortionLength()
 164 {
 165   if(!buf_)
 166     return 0;
 167
 168   if(!auth_tag_)
 169     return length_;
 170
 171   return (length_ > AUTHTAG_SIZE) ? (length_ - AUTHTAG_SIZE) : 0;
 172 }
 173
 174 void EncryptedPacket::withAuthTag(bool b)
 175 {
 176   if((b && auth_tag_) || (!b && !auth_tag_))
 177     return;
 178
 179   if(b)
 180   {
 181     if(length_ < (sizeof(struct HeaderStruct) + AUTHTAG_SIZE))
 182       throw std::runtime_error("auth-tag can't be enabled, buffer is too small");
 183
 184     auth_tag_ = buf_ + length_ - AUTHTAG_SIZE;
 185   }
 186   else
 187     auth_tag_ = NULL;
 188 }
 189
 190 void EncryptedPacket::addAuthTag()
 191 {
 192   if(auth_tag_)
 193     return;
 194
 195   auth_tag_ = buf_; // will be set to the correct value @ reinit
 196   setLength(length_ + AUTHTAG_SIZE);
 197   if(auth_tag_ == buf_) // reinit was not called by setLength
 198     reinit();
 199 }
 200
 201 void EncryptedPacket::removeAuthTag()
 202 {
 203   if(!auth_tag_)
 204     return;
 205
 206   auth_tag_ = NULL;
 207   setLength(length_ - AUTHTAG_SIZE);
 208 }
 209
 210 u_int8_t* EncryptedPacket::getAuthTag()
 211 {
 212   return auth_tag_;
 213 }
 214
 215 u_int32_t EncryptedPacket::getAuthTagLength()
 216 {
 217   if(auth_tag_)
 218     return AUTHTAG_SIZE;
 219
 220   return 0;
 221 }