text: /*
   * 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 <cstring>
  #include <tins/endianness.h>
  #include <tins/dhcp.h>
  #include <tins/exceptions.h>
  #include <tins/memory_helpers.h>
  
  using std::string;
  using std::vector;
  using std::runtime_error;
  
  using Tins::Memory::InputMemoryStream;
  using Tins::Memory::OutputMemoryStream;
  
  namespace Tins {
  
  PDU::metadata DHCP::extract_metadata(const uint8_t* /*buffer*/, uint32_t total_sz) {
      if (TINS_UNLIKELY(total_sz < sizeof(bootp_header))) {
          throw malformed_packet();
      }
      return {total_sz, pdu_flag, PDU::UNKNOWN};
  }
  
  // Magic cookie: uint32_t. 
  DHCP::DHCP() 
  : size_(sizeof(uint32_t)) {
      opcode(BOOTREQUEST);
      htype(1); // ethernet
      hlen(6); // MAC address length
  }
  
  DHCP::DHCP(const uint8_t* buffer, uint32_t total_sz) 
  : BootP(buffer, total_sz, 0), size_(sizeof(uint32_t)) {
      InputMemoryStream stream(buffer, total_sz);
      stream.skip(BootP::header_size() - vend().size());
      const auto magic_number = stream.read<uint32_t>();
      if (magic_number != Endian::host_to_be<uint32_t>(0x63825363)) {
          throw malformed_packet();
      }
      // While there's data left
      while (stream) {
          OptionTypes option_type;
          uint8_t option_length = 0;
          option_type = (OptionTypes)stream.read<uint8_t>();
          // We should only read the length if it's not END nor PAD
          if (option_type != END && option_type != PAD) {
              option_length = stream.read<uint8_t>();
          }
          // Make sure we can read the payload size
          if (!stream.can_read(option_length)) {
              throw malformed_packet();
          }
          add_option(option(option_type, option_length, stream.pointer()));
          stream.skip(option_length);
      }
  }
  
  void DHCP::add_option(const option& opt) {
      internal_add_option(opt);
      options_.push_back(opt);
  }
  
  void DHCP::internal_add_option(const option& opt) {
      size_ += static_cast<uint32_t>(opt.data_size() + (sizeof(uint8_t) << 1));
  }
  
  bool DHCP::remove_option(OptionTypes type) {
      auto iter = search_option_iterator(type);
      if (iter == options_.end()) {
          return false;
      }
      size_ -= static_cast<uint32_t>(iter->data_size() + (sizeof(uint8_t) << 1));
      options_.erase(iter);
      return true;
  }
  
  const DHCP::option* DHCP::search_option(OptionTypes opt) const {
      // Search for the iterator. If we found something, return it, otherwise return nullptr.
      auto iter = search_option_iterator(opt);
      return (iter != options_.end()) ? &*iter : nullptr;
  }
  
  DHCP::options_type::const_iterator DHCP::search_option_iterator(OptionTypes opt) const {
      return Internals::find_option_const<option>(options_, opt);
  }
  
  DHCP::options_type::iterator DHCP::search_option_iterator(OptionTypes opt) {
      return Internals::find_option<option>(options_, opt);
  }
  
  void DHCP::type(Flags type) {
      uint8_t int_type = type;
      add_option(option(DHCP_MESSAGE_TYPE, sizeof(uint8_t), &int_type));
  }
  
  void DHCP::end() {
      add_option(option(END));
  }
  
  uint8_t DHCP::type() const {
      return search_and_convert<uint8_t>(DHCP_MESSAGE_TYPE);
  }
  
  void DHCP::server_identifier(ipaddress_type ip) {
      uint32_t ip_int = ip;
      add_option(option(DHCP_SERVER_IDENTIFIER, sizeof(uint32_t), (const uint8_t*)&ip_int));
  }
  
  DHCP::ipaddress_type DHCP::server_identifier() const {
      return search_and_convert<ipaddress_type>(DHCP_SERVER_IDENTIFIER);
  }
  
  void DHCP::lease_time(uint32_t time) {
      time = Endian::host_to_be(time);
      add_option(option(DHCP_LEASE_TIME, sizeof(uint32_t), (const uint8_t*)&time));
  }
  
  uint32_t DHCP::lease_time() const {
      return search_and_convert<uint32_t>(DHCP_LEASE_TIME);
  }
  
  void DHCP::renewal_time(uint32_t time) {
      time = Endian::host_to_be(time);
      add_option(option(DHCP_RENEWAL_TIME, sizeof(uint32_t), (const uint8_t*)&time));
  }
          
  uint32_t DHCP::renewal_time() const {
      return search_and_convert<uint32_t>(DHCP_RENEWAL_TIME);
  }
  
  void DHCP::subnet_mask(ipaddress_type mask) {
      uint32_t mask_int = mask;
      add_option(option(SUBNET_MASK, sizeof(uint32_t), (const uint8_t*)&mask_int));
  }
  
  DHCP::ipaddress_type DHCP::subnet_mask() const {
      return search_and_convert<ipaddress_type>(SUBNET_MASK);
  }
  
  void DHCP::routers(const vector<ipaddress_type>& routers) {
      serialization_type buffer = serialize_list(routers);
      add_option(option(ROUTERS, buffer.begin(), buffer.end()));
  }
  
  vector<DHCP::ipaddress_type> DHCP::routers() const {
      return search_and_convert<vector<DHCP::ipaddress_type> >(ROUTERS);
  }
  
  void DHCP::domain_name_servers(const vector<ipaddress_type>& dns) {
      serialization_type buffer = serialize_list(dns);
      add_option(option(DOMAIN_NAME_SERVERS, buffer.begin(), buffer.end()));
  }
  
  vector<DHCP::ipaddress_type> DHCP::domain_name_servers() const {
      return search_and_convert<vector<DHCP::ipaddress_type> >(DOMAIN_NAME_SERVERS);
  }
  
  void DHCP::broadcast(ipaddress_type addr) {
      uint32_t int_addr = addr;
      add_option(option(BROADCAST_ADDRESS, sizeof(uint32_t), (uint8_t*)&int_addr));
  }
  
  DHCP::ipaddress_type DHCP::broadcast() const {
      return search_and_convert<ipaddress_type>(BROADCAST_ADDRESS);
  }
  
  void DHCP::requested_ip(ipaddress_type addr) {
      uint32_t int_addr = addr;
      add_option(option(DHCP_REQUESTED_ADDRESS, sizeof(uint32_t), (uint8_t*)&int_addr));
  }
  
  DHCP::ipaddress_type DHCP::requested_ip() const {
      return search_and_convert<ipaddress_type>(DHCP_REQUESTED_ADDRESS);
  }
  
  void DHCP::domain_name(const string& name) {
      add_option(option(DOMAIN_NAME, name.size(), (const uint8_t*)name.c_str()));
  }
  
  string DHCP::domain_name() const {
      return search_and_convert<string>(DOMAIN_NAME);
  }
  
  void DHCP::hostname(const string& name) {
      add_option(option(HOST_NAME, name.size(), (const uint8_t*)name.c_str()));
  }
  
  string DHCP::hostname() const {
      return search_and_convert<string>(HOST_NAME);
  }
  
  void DHCP::rebind_time(uint32_t time) {
      time = Endian::host_to_be(time);
      add_option(option(DHCP_REBINDING_TIME, sizeof(uint32_t), (uint8_t*)&time));
  }
          
  uint32_t DHCP::rebind_time() const {
      return search_and_convert<uint32_t>(DHCP_REBINDING_TIME);
  }
  
  PDU::serialization_type DHCP::serialize_list(const vector<ipaddress_type>& ip_list) {
      serialization_type buffer(ip_list.size() * sizeof(uint32_t));
      auto* ptr = (uint32_t*)&buffer[0];
      using iterator = vector<ipaddress_type>::const_iterator;
      for (auto it : ip_list) {
          *(ptr++) = it;
      }
      return buffer;
  }
  
  uint32_t DHCP::header_size() const {
      return static_cast<uint32_t>(BootP::header_size() - vend().size() + size_);
  }
  
  void DHCP::write_serialization(uint8_t* buffer, uint32_t total_sz) {
      if (size_) {
          vend_type& result = BootP::vend();
          result.resize(size_);
          // Build a stream over the vend vector
          OutputMemoryStream stream(&result[0], result.size());
          // Magic cookie
          stream.write(Endian::host_to_be<uint32_t>(0x63825363));
          for (const auto & option : options_) {
              stream.write(option.option());
              stream.write<uint8_t>(option.length_field());
              stream.write(option.data_ptr(), option.data_size());
          }
      }
      BootP::write_serialization(buffer, total_sz);
  }
  
  } // Tins
  