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// Copyright (C) 2012-2020 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/.
#include <config.h>
#include <perfdhcp/pkt_transform.h>
#include <perfdhcp/localized_option.h>
#include <perfdhcp/stats_mgr.h>
#include <exceptions/exceptions.h>
#include <dhcp/option.h>
#include <dhcp/libdhcp++.h>
#include <dhcp/dhcp6.h>
#include <iostream>
using namespace std;
using namespace isc;
using namespace dhcp;
namespace isc {
namespace perfdhcp {
bool
PktTransform::pack(const Option::Universe universe,
const OptionBuffer& in_buffer,
const OptionCollection& options,
const size_t transid_offset,
const uint32_t transid,
util::OutputBuffer& out_buffer) {
// Always override the packet if function is called.
out_buffer.clear();
// Write whole buffer to output buffer.
out_buffer.writeData(&in_buffer[0], in_buffer.size());
uint8_t transid_len = (universe == Option::V6) ? 3 : 4;
if ((transid_offset + transid_len >= in_buffer.size()) ||
(transid_offset == 0)) {
cout << "Failed to build packet: provided transaction id offset: "
<< transid_offset << " is out of bounds (expected 1.."
<< in_buffer.size()-1 << ")." << endl;
return (false);
}
try {
size_t offset_ptr = transid_offset;
if (universe == Option::V4) {
out_buffer.writeUint8At(transid >> 24 & 0xFF, offset_ptr++);
}
out_buffer.writeUint8At(transid >> 16 & 0xFF, offset_ptr++);
out_buffer.writeUint8At(transid >> 8 & 0xFF, offset_ptr++);
out_buffer.writeUint8At(transid & 0xFF, offset_ptr++);
// We already have packet template stored in output buffer
// but still some options have to be updated if client
// specified them along with their offsets in the buffer.
PktTransform::packOptions(in_buffer, options, out_buffer);
} catch (const isc::BadValue& e) {
cout << "Building packet failed: " << e.what() << endl;
return (false);
}
return (true);
}
bool
PktTransform::unpack(const Option::Universe universe,
const OptionBuffer& in_buffer,
const OptionCollection& options,
const size_t transid_offset,
uint32_t& transid) {
uint8_t transid_len = (universe == Option::V6) ? 3 : 4;
// Validate transaction id offset.
if ((transid_offset + transid_len + 1 > in_buffer.size()) ||
(transid_offset == 0)) {
cout << "Failed to parse packet: provided transaction id offset: "
<< transid_offset << " is out of bounds (expected 1.."
<< in_buffer.size()-1 << ")." << endl;
return (false);
}
// Read transaction id from the buffer.
// For DHCPv6 we transaction id is 3 bytes long so the high byte
// of transid will be zero.
OptionBufferConstIter it = in_buffer.begin() + transid_offset;
transid = 0;
for (int i = 0; i < transid_len; ++i, ++it) {
// Read next byte and shift it left to its position in
// transid (shift by the number of bytes read so far.
transid += *it << (transid_len - i - 1) * 8;
}
try {
PktTransform::unpackOptions(in_buffer, options);
} catch (const isc::BadValue& e) {
ExchangeStats::malformed_pkts_++;
cout << "Packet parsing failed: " << e.what() << endl;
return (false);
}
return (true);
}
void
PktTransform::packOptions(const OptionBuffer& in_buffer,
const OptionCollection& options,
util::OutputBuffer& out_buffer) {
try {
// If there are any options on the list, we will use provided
// options offsets to override them in the output buffer
// with new contents.
for (OptionCollection::const_iterator it = options.begin();
it != options.end(); ++it) {
// Get options with their position (offset).
boost::shared_ptr<LocalizedOption> option =
boost::dynamic_pointer_cast<LocalizedOption>(it->second);
if (option == NULL) {
isc_throw(isc::BadValue, "option is null");
}
uint32_t offset = option->getOffset();
if ((offset == 0) ||
(offset + option->len() > in_buffer.size())) {
isc_throw(isc::BadValue,
"option offset for option: " << option->getType()
<< " is out of bounds (expected 1.."
<< in_buffer.size() - option->len() << ")");
}
// Create temporary buffer to store option contents.
util::OutputBuffer buf(option->len());
// Pack option contents into temporary buffer.
option->pack(buf);
// OutputBuffer class has nice functions that write
// data at the specified position so we can use it to
// inject contents of temporary buffer to output buffer.
const uint8_t *buf_data =
static_cast<const uint8_t*>(buf.getData());
for (size_t i = 0; i < buf.getLength(); ++i) {
out_buffer.writeUint8At(buf_data[i], offset + i);
}
}
}
catch (const Exception&) {
isc_throw(isc::BadValue, "failed to pack options into buffer.");
}
}
void
PktTransform::unpackOptions(const OptionBuffer& in_buffer,
const OptionCollection& options) {
for (OptionCollection::const_iterator it = options.begin();
it != options.end(); ++it) {
boost::shared_ptr<LocalizedOption> option =
boost::dynamic_pointer_cast<LocalizedOption>(it->second);
if (option == NULL) {
isc_throw(isc::BadValue, "option is null");
}
size_t opt_pos = option->getOffset();
if (opt_pos == 0) {
isc_throw(isc::BadValue, "failed to unpack packet from raw buffer "
"(Option position not specified)");
} else if (opt_pos + option->getHeaderLen() > in_buffer.size()) {
isc_throw(isc::BadValue,
"failed to unpack options from from raw buffer "
"(Option position out of bounds)");
}
size_t offset = opt_pos;
size_t offset_step = 1;
uint16_t opt_type = 0;
if (option->getUniverse() == Option::V6) {
offset_step = 2;
// For DHCPv6 option type is in first two octets.
opt_type = in_buffer[offset] * 256 + in_buffer[offset + 1];
} else {
// For DHCPv4 option type is in first octet.
opt_type = in_buffer[offset];
}
// Check if we got expected option type.
if (opt_type != option->getType()) {
isc_throw(isc::BadValue,
"failed to unpack option from raw buffer "
"(option type mismatch)");
}
// Get option length which is supposed to be after option type.
offset += offset_step;
const uint16_t opt_len =
(option->getUniverse() == Option::V6) ?
in_buffer[offset] * 256 + in_buffer[offset + 1] :
in_buffer[offset];
// Check if packet is not truncated.
if (offset + option->getHeaderLen() + opt_len > in_buffer.size()) {
isc_throw(isc::BadValue,
"failed to unpack option from raw buffer "
"(option truncated)");
}
// Seek to actual option data and replace it.
offset += offset_step;
option->setData(in_buffer.begin() + offset,
in_buffer.begin() + offset + opt_len);
}
}
void
PktTransform::writeAt(dhcp::OptionBuffer& in_buffer, size_t dest_pos,
dhcp::OptionBuffer::iterator first,
dhcp::OptionBuffer::iterator last) {
memcpy(&in_buffer[dest_pos], &(*first), std::distance(first, last));
}
} // namespace perfdhcp
} // namespace isc
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