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// Copyright (C) 2012-2019 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef PKT_TRANSFORM_H
#define PKT_TRANSFORM_H
#include <perfdhcp/localized_option.h>
#include <dhcp/option.h>
namespace isc {
namespace perfdhcp {
/// \brief Read and write raw data to DHCP packets.
///
/// This class provides static functions to read/write raw data from/to the
/// packet buffer. When reading data with the unpack() method, the
/// corresponding options objects are updated. When writing to the packet
/// buffer with pack(), options objects carry input data to be written.
///
/// This class is used both by \ref PerfPkt4 and
/// \ref PerfPkt6 classes in case DHCP packets are created
/// from template files. In this case, some of the template
/// packet's options are replaced before sending it to the
/// server. Offset of specific options are provided from the
/// command line by the perfdhcp tool user, and passed in an
/// options collection.
class PktTransform {
public:
/// \brief Prepares on-wire format from raw buffer.
///
/// The method copies the input buffer and options contents
/// to the output buffer. The input buffer must contain whole
/// initial packet data. Parts of this data will be
/// overridden by options data specified in an options
/// collection. Such options must have their offsets within
/// a packet specified (see \ref LocalizedOption to find out
/// how to specify options offset).
///
/// \note The specified options must fit into the size of the
/// initial packet data. A call to this method will fail
/// if the option's offset + its size is beyond the packet's size.
///
/// \param universe Universe used, V4 or V6
/// \param in_buffer Input buffer holding initial packet
/// data, this can be directly read from template file
/// \param options Options collection with offsets
/// \param transid_offset offset of transaction id in a packet,
/// transaction ID will be written to output buffer at this
/// offset
/// \param transid Transaction ID value
/// \param out_buffer Output buffer holding "packed" data
///
/// \return false, if pack operation failed.
static bool pack(const dhcp::Option::Universe universe,
const dhcp::OptionBuffer& in_buffer,
const dhcp::OptionCollection& options,
const size_t transid_offset,
const uint32_t transid,
util::OutputBuffer& out_buffer);
/// \brief Handles selective binary packet parsing.
///
/// This method handles the parsing of packets that have non-default
/// options or transaction ID offsets. The client class has to use
/// \ref isc::dhcp::Pkt6::addOption to specify which options to parse.
/// Each option should be of the \ref isc::perfdhcp::LocalizedOption
/// type with the offset value specified.
///
/// \param universe universe used, V4 or V6
/// \param in_buffer input buffer to be parsed
/// \param options options collection with options offsets
/// \param transid_offset offset of transaction id in input buffer
/// \param transid transaction id value read from input buffer
///
/// \return false, if unpack operation failed.
static bool unpack(const dhcp::Option::Universe universe,
const dhcp::OptionBuffer& in_buffer,
const dhcp::OptionCollection& options,
const size_t transid_offset,
uint32_t& transid);
/// \brief Replace contents of buffer with vector.
///
/// Function replaces data of the buffer with data from vector.
///
/// \param in_buffer destination buffer.
/// \param dest_pos position in destination buffer.
/// \param first beginning of data range in source vector.
/// \param last end of data range in source vector.
static void writeAt(dhcp::OptionBuffer& in_buffer, size_t dest_pos,
std::vector<uint8_t>::iterator first,
std::vector<uint8_t>::iterator last);
/// \brief Replace contents of one vector with uint16 value.
///
/// Function replaces data inside one vector with uint16_t value.
///
/// \param in_buffer destination buffer.
/// \param dest_pos position in destination buffer.
/// \param val value to be written.
template<typename T>
static void writeValueAt(dhcp::OptionBuffer& in_buffer, size_t dest_pos,
T val) {
// @todo consider replacing the loop with switch statement
// checking sizeof(T).
for (int i = 0; i < sizeof(T); ++i) {
in_buffer[dest_pos + i] = (val >> 8 * (sizeof(T) - i - 1)) & 0xFF;
}
}
private:
/// \brief Replaces contents of options in a buffer.
///
/// The method uses a localized options collection to
/// replace parts of packet data (e.g. data read
/// from template file).
/// This private method is called from \ref PktTransform::pack
///
/// \param in_buffer input buffer holding initial packet data.
/// \param out_buffer output buffer with "packed" options.
/// \param options options collection with actual data and offsets.
///
/// \throw isc::Unexpected if options update failed.
static void packOptions(const dhcp::OptionBuffer& in_buffer,
const dhcp::OptionCollection& options,
util::OutputBuffer& out_buffer);
/// \brief Reads contents of specified options from buffer.
///
/// The method reads options data from the input buffer
/// and stores it in options objects. Offsets of the options
/// must be specified (see \ref LocalizedOption to find out how to specify
/// the option offset).
/// This private method is called by \ref PktTransform::unpack.
///
/// \note This method iterates through all options in an
/// options collection, checks the offset of the option
/// in input buffer and reads data from the buffer to
/// update the option's buffer. If the provided options collection
/// is empty, a call to this method will have no effect.
///
/// \param universe universe used, V4 or V6
/// \param in_buffer input buffer to be parsed.
/// \param options options collection with their offsets
/// in input buffer specified.
///
/// \throw isc::Unexpected if options unpack failed.
static void unpackOptions(const dhcp::OptionBuffer& in_buffer,
const dhcp::OptionCollection& options);
};
} // namespace perfdhcp
} // namespace isc
#endif // PKT_TRANSFORM_H
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