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// Copyright (C) 2010-2015 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 <stdint.h>
#include <cassert>
#include <vector>
#include <exceptions/exceptions.h>
#include <util/buffer.h>
#include <dns/messagerenderer.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdatafields.h>
using namespace std;
using namespace isc::dns;
using namespace isc::dns::rdata;
using isc::util::OutputBuffer;
using isc::util::InputBuffer;
namespace isc {
namespace dns {
namespace rdata {
/// This is a helper class for \c RdataFields.
///
/// It manages a local storage for the data when \c RdataFields is constructed
/// from an \c Rdata.
/// To minimize construction overhead in the other case, an instance of
/// this class is instantiated only when necessary - we don't need the vectors
/// when only rendering.
struct RdataFields::RdataFieldsDetail {
RdataFieldsDetail(const vector<FieldSpec>& fields,
const uint8_t* data, size_t data_length) :
allocated_fields_(fields),
allocated_data_(data, data + data_length)
{}
const vector<FieldSpec> allocated_fields_;
const vector<uint8_t> allocated_data_;
};
namespace {
// This class is used to divide the content of RDATA into \c RdataField
// fields via message rendering logic.
// The idea is to identify domain name fields in the writeName() method,
// and determine whether they are compressible using the "compress"
// parameter.
// Other types of data are simply copied into the internal buffer, and
// consecutive such fields are combined into a single \c RdataField field.
//
// Technically, this use of inheritance may be considered a violation of
// Liskov Substitution Principle in that it doesn't actually compress domain
// names, and some of the methods are not expected to be used.
// In fact, skip() or trim() may not be make much sense in this context.
// Nevertheless we keep this idea at the moment. Since the usage is limited
// (it's only used within this file, and only used with \c Rdata variants),
// it's hopefully an acceptable practice.
class RdataFieldComposer : public AbstractMessageRenderer {
public:
RdataFieldComposer() :
truncated_(false), length_limit_(65535),
mode_(CASE_INSENSITIVE), last_data_pos_(0)
{}
virtual ~RdataFieldComposer() {}
virtual bool isTruncated() const { return (truncated_); }
virtual size_t getLengthLimit() const { return (length_limit_); }
virtual CompressMode getCompressMode() const { return (mode_); }
virtual void setTruncated() { truncated_ = true; }
virtual void setLengthLimit(size_t len) { length_limit_ = len; }
virtual void setCompressMode(CompressMode mode) { mode_ = mode; }
virtual void writeName(const LabelSequence&, bool) {}
virtual void writeName(const Name& name, bool compress) {
extendData();
const RdataFields::Type field_type =
compress ? RdataFields::COMPRESSIBLE_NAME :
RdataFields::INCOMPRESSIBLE_NAME;
// TODO: When we get rid of need for getBuffer, we can output the name
// to a buffer and then write the buffer inside
name.toWire(getBuffer());
fields_.push_back(RdataFields::FieldSpec(field_type,
name.getLength()));
last_data_pos_ = getLength();
}
virtual void clear() {
isc_throw(Unexpected, "unexpected clear() for RdataFieldComposer");
}
bool truncated_;
size_t length_limit_;
CompressMode mode_;
vector<RdataFields::FieldSpec> fields_;
vector<RdataFields::FieldSpec>& getFields() {
extendData();
return (fields_);
}
// We use generict write* methods, with the exception of writeName.
// So new data can arrive without us knowing it, this considers all new
// data to be just data and extends the fields to take it into account.
size_t last_data_pos_;
void extendData() {
// No news, return to work
if (getLength() == last_data_pos_) {
return;
}
// The new bytes are just ordinary uninteresting data
if (fields_.empty() || fields_.back().type != RdataFields::DATA) {
fields_.push_back(RdataFields::FieldSpec(RdataFields::DATA, 0));
}
// We added this much data from last time
fields_.back().len += getLength() - last_data_pos_;
last_data_pos_ = getLength();
}
};
}
RdataFields::RdataFields(const Rdata& rdata) {
RdataFieldComposer field_composer;
rdata.toWire(field_composer);
nfields_ = field_composer.getFields().size();
data_length_ = field_composer.getLength();
if (nfields_ > 0) {
assert(data_length_ > 0);
detail_ = new RdataFieldsDetail(field_composer.getFields(),
static_cast<const uint8_t*>
(field_composer.getData()),
field_composer.getLength());
data_ = &detail_->allocated_data_[0];
fields_ = &detail_->allocated_fields_[0];
} else {
assert(data_length_ == 0);
detail_ = NULL;
data_ = NULL;
fields_ = NULL;
}
}
RdataFields::RdataFields(const void* fields, const unsigned int fields_length,
const void* data, const size_t data_length) :
fields_(static_cast<const FieldSpec*>(fields)),
nfields_(fields_length / sizeof(*fields_)),
data_(static_cast<const uint8_t*>(data)),
data_length_(data_length),
detail_(NULL)
{
if ((fields_ == NULL && nfields_ > 0) ||
(fields_ != NULL && nfields_ == 0)) {
isc_throw(InvalidParameter,
"Inconsistent parameters for RdataFields: fields_length ("
<< fields_length << ") and fields conflict each other");
}
if ((data_ == NULL && data_length_ > 0) ||
(data_ != NULL && data_length_ == 0)) {
isc_throw(InvalidParameter,
"Inconsistent parameters for RdataFields: data length ("
<< data_length_ << ") and data conflict each other");
}
size_t total_length = 0;
for (unsigned int i = 0; i < nfields_; ++i) {
total_length += fields_[i].len;
}
if (total_length != data_length_) {
isc_throw(InvalidParameter,
"Inconsistent parameters for RdataFields: "
"fields len: " << total_length <<
" data len: " << data_length_);
}
}
RdataFields::~RdataFields() {
delete detail_;
}
RdataFields::FieldSpec
RdataFields::getFieldSpec(const unsigned int field_id) const {
if (field_id >= nfields_) {
isc_throw(OutOfRange, "Rdata field ID is out of range: " << field_id);
}
return (fields_[field_id]);
}
void
RdataFields::toWire(AbstractMessageRenderer& renderer) const {
size_t offset = 0;
for (unsigned int i = 0; i < nfields_; ++i) {
if (fields_[i].type == DATA) {
renderer.writeData(data_ + offset, fields_[i].len);
} else {
// XXX: this is inefficient. Even if it's quite likely the
// data is a valid wire representation of a name we parse
// it to construct the Name object in the generic mode.
// This should be improved in a future version.
InputBuffer buffer(data_ + offset, fields_[i].len);
renderer.writeName(Name(buffer),
fields_[i].type == COMPRESSIBLE_NAME);
}
offset += fields_[i].len;
}
}
void
RdataFields::toWire(OutputBuffer& buffer) const {
buffer.writeData(data_, data_length_);
}
} // end of namespace rdata
} // end of namespace dns
} // end of namespace isc
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