kea/src/lib/dhcp/option_custom.cc

// Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include <dhcp/libdhcp++.h>
#include <dhcp/option_data_types.h>
#include <dhcp/option_custom.h>
#include <util/encode/hex.h>

namespace isc {
namespace dhcp {

OptionCustom::OptionCustom(const OptionDefinition& def,
                           Universe u)
    : Option(u, def.getCode(), OptionBuffer()),
      definition_(def) {
    createBuffers();
}

OptionCustom::OptionCustom(const OptionDefinition& def,
                             Universe u,
                             const OptionBuffer& data)
    : Option(u, def.getCode(), data.begin(), data.end()),
      definition_(def) {
    // It is possible that no data is provided if an option
    // is being created on a server side. In such case a bunch
    // of buffers with default values is first created and then
    // the values are replaced using writeXXX functions. Thus
    // we need to detect that no data has been specified and
    // take a different code path.
    if (!data_.empty()) {
        createBuffers(data_);
    } else {
        createBuffers();
    }
}

OptionCustom::OptionCustom(const OptionDefinition& def,
                             Universe u,
                             OptionBufferConstIter first,
                             OptionBufferConstIter last)
    : Option(u, def.getCode(), first, last),
      definition_(def) {
    createBuffers(data_);
}

void
OptionCustom::addArrayDataField(const asiolink::IOAddress& address) {
    checkArrayType();

    if ((address.isV4() && definition_.getType() != OPT_IPV4_ADDRESS_TYPE) ||
        (address.isV6() && definition_.getType() != OPT_IPV6_ADDRESS_TYPE)) {
        isc_throw(BadDataTypeCast, "invalid address specified "
                  << address.toText() << ". Expected a valid IPv"
                  << (definition_.getType() == OPT_IPV4_ADDRESS_TYPE ?
                      "4" : "6") << " address.");
    }

    OptionBuffer buf;
    OptionDataTypeUtil::writeAddress(address, buf);
    buffers_.push_back(buf);
}

void
OptionCustom::addArrayDataField(const bool value) {
    checkArrayType();

    OptionBuffer buf;
    OptionDataTypeUtil::writeBool(value, buf);
    buffers_.push_back(buf);
}

void
OptionCustom::checkIndex(const uint32_t index) const {
    if (index >= buffers_.size()) {
        isc_throw(isc::OutOfRange, "specified data field index " << index
                  << " is out of range.");
    }
}

template<typename T>
void
OptionCustom::checkDataType(const uint32_t index) const {
    // Check that the requested return type is a supported integer.
    if (!OptionDataTypeTraits<T>::integer_type) {
        isc_throw(isc::dhcp::InvalidDataType, "specified data type"
                  " is not a supported integer type.");
    }

    // Get the option definition type.
    OptionDataType data_type = definition_.getType();
    if (data_type == OPT_RECORD_TYPE) {
        const OptionDefinition::RecordFieldsCollection& record_fields =
            definition_.getRecordFields();
        // When we initialized buffers we have already checked that
        // the number of these buffers is equal to number of option
        // fields in the record so the condition below should be met.
        assert(index < record_fields.size());
        // Get the data type to be returned.
        data_type = record_fields[index];
    }

    if (OptionDataTypeTraits<T>::type != data_type) {
        isc_throw(isc::dhcp::InvalidDataType,
                  "specified data type " << data_type << " does not"
                  " match the data type in an option definition for field"
                  " index " << index);
    }
}

void
OptionCustom::createBuffers() {
    definition_.validate();

    std::vector<OptionBuffer> buffers;

    OptionDataType data_type = definition_.getType();
    // This function is called when an empty data buffer has been
    // passed to the constructor. In such cases values for particular
    // data fields will be set using modifier functions but for now
    // we need to initialize a set of buffers that are specified
    // for an option by its definition. Since there is no data yet,
    // we are going to fill these buffers with default values.
    if (data_type == OPT_RECORD_TYPE) {
        // For record types we need to iterate over all data fields
        // specified in option definition and create corresponding
        // buffers for each of them.
        const OptionDefinition::RecordFieldsCollection fields =
            definition_.getRecordFields();

        for (OptionDefinition::RecordFieldsConstIter field = fields.begin();
             field != fields.end(); ++field) {
            OptionBuffer buf;

            // For data types that have a fixed size we can use the
            // utility function to get the buffer's size.
            size_t data_size = OptionDataTypeUtil::getDataTypeLen(*field);

            // For variable data sizes the utility function returns zero.
            // It is ok for string values because the default string
            // is 'empty'. However for FQDN the empty value is not valid
            // so we initialize it to '.'.
            if (data_size == 0 &&
                *field == OPT_FQDN_TYPE) {
                OptionDataTypeUtil::writeFqdn(".", buf);
            } else {
                // At this point we can resize the buffer. Note that
                // for string values we are setting the empty buffer
                // here.
                buf.resize(data_size);
            }
            // We have the buffer with default value prepared so we
            // add it to the set of buffers.
            buffers.push_back(buf);
        }
    } else if (!definition_.getArrayType() &&
               data_type != OPT_EMPTY_TYPE) {
        // For either 'empty' options we don't have to create any buffers
        // for obvious reason. For arrays we also don't create any buffers
        // yet because the set of fields that belong to the array is open
        // ended so we can't allocate required buffers until we know how
        // many of them are needed.
        // For non-arrays we have a single value being held by the option
        // so we have to allocate exactly one buffer.
        OptionBuffer buf;
        size_t data_size = OptionDataTypeUtil::getDataTypeLen(data_type);
        if (data_size == 0 &&
            data_type == OPT_FQDN_TYPE) {
            OptionDataTypeUtil::writeFqdn(".", buf);
        } else {
            // Note that if our option holds a string value then
            // we are making empty buffer here.
            buf.resize(data_size);
        }
        // Add a buffer that we have created and leave.
        buffers.push_back(buf);
    }
    // The 'swap' is used here because we want to make sure that we
    // don't touch buffers_ until we successfully allocate all
    // buffers to be stored there.
    std::swap(buffers, buffers_);
}

void
OptionCustom::createBuffers(const OptionBuffer& data_buf) {
    // Check that the option definition is correct as we are going
    // to use it to split the data_ buffer into set of sub buffers.
    definition_.validate();

    std::vector<OptionBuffer> buffers;
    OptionBuffer::const_iterator data = data_buf.begin();

    OptionDataType data_type = definition_.getType();
    if (data_type == OPT_RECORD_TYPE) {
        // An option comprises a record of data fields. We need to
        // get types of these data fields to allocate enough space
        // for each buffer.
        const OptionDefinition::RecordFieldsCollection& fields =
            definition_.getRecordFields();

        // Go over all data fields within a record.
        for (OptionDefinition::RecordFieldsConstIter field = fields.begin();
             field != fields.end(); ++field) {
            // For fixed-size data type such as boolean, integer, even
            // IP address we can use the utility function to get the required
            // buffer size.
            size_t data_size = OptionDataTypeUtil::getDataTypeLen(*field);

            // For variable size types (e.g. string) the function above will
            // return 0 so we need to do a runtime check of the length.
            if (data_size == 0) {
                // FQDN is a special data type as it stores variable length data
                // but the data length is encoded in the buffer. The easiest way
                // to obtain the length of the data is to read the FQDN. The
                // utility function will return the size of the buffer on success.
                if (*field == OPT_FQDN_TYPE) {
                    std::string fqdn =
                        OptionDataTypeUtil::readFqdn(OptionBuffer(data, data_buf.end()));
                    // The size of the buffer holding an FQDN is always
                    // 1 byte larger than the size of the string
                    // representation of this FQDN.
                    data_size = fqdn.size() + 1;
                } else {
                    // In other case we are dealing with string or binary value
                    // which size can't be determined. Thus we consume the
                    // remaining part of the buffer for it. Note that variable
                    // size data can be laid at the end of the option only and
                    // that the validate() function in OptionDefinition object
                    // should have checked wheter it is a case for this option.
                    data_size = std::distance(data, data_buf.end());
                }
                if (data_size == 0) {
                    // If we reached the end of buffer we assume that this option is
                    // truncated because there is no remaining data to initialize
                    // an option field.
                    if (data_size == 0) {
                        isc_throw(OutOfRange, "option buffer truncated");
                    }
                }
            } else {
                // Our data field requires that there is a certain chunk of
                // data left in the buffer. If not, option is truncated.
                if (std::distance(data, data_buf.end()) < data_size) {
                    isc_throw(OutOfRange, "option buffer truncated");
                }
            }
            // Store the created buffer.
            buffers.push_back(OptionBuffer(data, data + data_size));
            // Proceed to the next data field.
            data += data_size;
        }
    } else if (data_type != OPT_EMPTY_TYPE) {
        // If data_type value is other than OPT_RECORD_TYPE, our option is
        // empty (have no data at all) or it comprises one or more
        // data fields of the same type. The type of those fields
        // is held in the data_type variable so let's use it to determine
        // a size of buffers.
        size_t data_size = OptionDataTypeUtil::getDataTypeLen(data_type);
        // The check below will fail if the input buffer is too short
        // for the data size being held by this option.
        // Note that data_size returned by getDataTypeLen may be zero
        // if variable length data is being held by the option but
        // this will not cause this check to throw exception.
        if (std::distance(data, data_buf.end()) < data_size) {
            isc_throw(OutOfRange, "option buffer truncated");
        }
        // For an array of values we are taking different path because
        // we have to handle multiple buffers.
        if (definition_.getArrayType()) {
            while (data != data_buf.end()) {
                // FQDN is a special case because it is of a variable length.
                // The actual length for a particular FQDN is encoded within
                // a buffer so we have to actually read the FQDN from a buffer
                // to get it.
                if (data_type == OPT_FQDN_TYPE) {
                    std::string fqdn =
                        OptionDataTypeUtil::readFqdn(OptionBuffer(data, data_buf.end()));
                    // The size of the buffer holding an FQDN is always
                    // 1 byte larger than the size of the string
                    // representation of this FQDN.
                    data_size = fqdn.size() + 1;
                }
                // We don't perform other checks for data types that can't be
                // used together with array indicator such as strings, empty field
                // etc. This is because OptionDefinition::validate function should
                // have checked this already. Thus data_size must be greater than
                // zero.
                assert(data_size > 0);
                // Get chunks of data and store as a collection of buffers.
                // Truncate any remaining part which length is not divisible by
                // data_size. Note that it is ok to truncate the data if and only
                // if the data buffer is long enough to keep at least one value.
                // This has been checked above already.
                if (std::distance(data, data_buf.end()) < data_size) {
                    break;
                }
                buffers.push_back(OptionBuffer(data, data + data_size));
                data += data_size;
            }
        } else {
            // For non-arrays the data_size can be zero because
            // getDataTypeLen returns zero for variable size data types
            // such as strings. Simply take whole buffer.
            if (data_size == 0) {
                // For FQDN we get the size by actually reading the FQDN.
                if (data_type == OPT_FQDN_TYPE) {
                    std::string fqdn =
                        OptionDataTypeUtil::readFqdn(OptionBuffer(data, data_buf.end()));
                    // The size of the buffer holding an FQDN is always
                    // 1 bytes larger than the size of the string
                    // representation of this FQDN.
                    data_size = fqdn.size() + 1;
                } else {
                    data_size = std::distance(data, data_buf.end());
                }
            }
            if (data_size > 0) {
                buffers.push_back(OptionBuffer(data, data + data_size));
            } else {
                isc_throw(OutOfRange, "option buffer truncated");
            }
        }
    }
    // If everything went ok we can replace old buffer set with new ones.
    std::swap(buffers_, buffers);
}

std::string
OptionCustom::dataFieldToText(const OptionDataType data_type,
                              const uint32_t index) const {
    std::ostringstream text;

    // Get the value of the data field.
    switch (data_type) {
    case OPT_BINARY_TYPE:
        text << util::encode::encodeHex(readBinary(index));
        break;
    case OPT_BOOLEAN_TYPE:
        text << (readBoolean(index) ? "true" : "false");
        break;
    case OPT_INT8_TYPE:
        text << readInteger<int8_t>(index);
        break;
    case OPT_INT16_TYPE:
        text << readInteger<int16_t>(index);
        break;
    case OPT_INT32_TYPE:
        text << readInteger<int32_t>(index);
        break;
    case OPT_UINT8_TYPE:
        text << readInteger<uint8_t>(index);
        break;
    case OPT_UINT16_TYPE:
        text << readInteger<uint16_t>(index);
        break;
    case OPT_UINT32_TYPE:
        text << readInteger<uint32_t>(index);
        break;
    case OPT_IPV4_ADDRESS_TYPE:
    case OPT_IPV6_ADDRESS_TYPE:
        text << readAddress(index).toText();
        break;
    case OPT_FQDN_TYPE:
        text << readFqdn(index);
        break;
    case OPT_STRING_TYPE:
        text << readString(index);
        break;
    default:
        ;
    }

    // Append data field type in brackets.
    text << " ( " << OptionDataTypeUtil::getDataTypeName(data_type) << " ) ";

    return (text.str());
}

void
OptionCustom::pack4(isc::util::OutputBuffer& buf) {
    if (len() > 255) {
        isc_throw(OutOfRange, "DHCPv4 Option " << type_
                  << " value is too high. At most 255 is supported.");
    }

    buf.writeUint8(type_);
    buf.writeUint8(len() - getHeaderLen());

    // Write data from buffers.
    for (std::vector<OptionBuffer>::const_iterator it = buffers_.begin();
         it != buffers_.end(); ++it) {
        // In theory the createBuffers function should have taken
        // care that there are no empty buffers added to the
        // collection but it is almost always good to make sure.
        if (!it->empty()) {
            buf.writeData(&(*it)[0], it->size());
        }
    }

    // Write suboptions.
    packOptions(buf);
}

void
OptionCustom::pack6(isc::util::OutputBuffer& buf) {
    buf.writeUint16(type_);
    buf.writeUint16(len() - getHeaderLen());

    // Write data from buffers.
    for (std::vector<OptionBuffer>::const_iterator it = buffers_.begin();
         it != buffers_.end(); ++it) {
        if (!it->empty()) {
            buf.writeData(&(*it)[0], it->size());
        }
    }

    packOptions(buf);
}

asiolink::IOAddress
OptionCustom::readAddress(const uint32_t index) const {
    checkIndex(index);

    // The address being read can be either IPv4 or IPv6. The decision
    // is made based on the buffer length. If it holds 4 bytes it is IPv4
    // address, if it holds 16 bytes it is IPv6.
    if (buffers_[index].size() == asiolink::V4ADDRESS_LEN) {
        return (OptionDataTypeUtil::readAddress(buffers_[index], AF_INET));
    } else if (buffers_[index].size() == asiolink::V6ADDRESS_LEN) {
        return (OptionDataTypeUtil::readAddress(buffers_[index], AF_INET6));
    } else {
        isc_throw(BadDataTypeCast, "unable to read data from the buffer as"
                  << " IP address. Invalid buffer length "
                  << buffers_[index].size() << ".");
    }
}

void
OptionCustom::writeAddress(const asiolink::IOAddress& address,
                           const uint32_t index) {
    using namespace isc::asiolink;

    checkIndex(index);

    if ((address.isV4() && buffers_[index].size() != V4ADDRESS_LEN) ||
        (address.isV6() && buffers_[index].size() != V6ADDRESS_LEN)) {
        isc_throw(BadDataTypeCast, "invalid address specified "
                  << address.toText() << ". Expected a valid IPv"
                  << (buffers_[index].size() == V4ADDRESS_LEN ? "4" : "6")
                  << " address.");
    }

    OptionBuffer buf;
    OptionDataTypeUtil::writeAddress(address, buf);
    std::swap(buf, buffers_[index]);
}

const OptionBuffer&
OptionCustom::readBinary(const uint32_t index) const {
    checkIndex(index);
    return (buffers_[index]);
}

void
OptionCustom::writeBinary(const OptionBuffer& buf,
                          const uint32_t index) {
    checkIndex(index);
    buffers_[index] = buf;
}

bool
OptionCustom::readBoolean(const uint32_t index) const {
    checkIndex(index);
    return (OptionDataTypeUtil::readBool(buffers_[index]));
}

void
OptionCustom::writeBoolean(const bool value, const uint32_t index) {
    checkIndex(index);

    buffers_[index].clear();
    OptionDataTypeUtil::writeBool(value, buffers_[index]);
}

std::string
OptionCustom::readFqdn(const uint32_t index) const {
    checkIndex(index);
    return (OptionDataTypeUtil::readFqdn(buffers_[index]));
}

void
OptionCustom::writeFqdn(const std::string& fqdn, const uint32_t index) {
    checkIndex(index);

    // Create a temporay buffer where the FQDN will be written.
    OptionBuffer buf;
    // Try to write to the temporary buffer rather than to the
    // buffers_ member directly guarantees that we don't modify
    // (clear) buffers_ until we are sure that the provided FQDN
    // is valid.
    OptionDataTypeUtil::writeFqdn(fqdn, buf);
    // If we got to this point it means that the FQDN is valid.
    // We can move the contents of the teporary buffer to the
    // target buffer.
    std::swap(buffers_[index], buf);
}

std::string
OptionCustom::readString(const uint32_t index) const {
    checkIndex(index);
    return (OptionDataTypeUtil::readString(buffers_[index]));
}

void
OptionCustom::writeString(const std::string& text, const uint32_t index) {
    checkIndex(index);

    // Let's clear a buffer as we want to replace the value of the
    // whole buffer. If we fail to clear the buffer the data will
    // be appended.
    buffers_[index].clear();
    // If the text value is empty we can leave because the buffer
    // is already empty.
    if (!text.empty()) {
        OptionDataTypeUtil::writeString(text, buffers_[index]);
    }
}

void
OptionCustom::unpack(OptionBufferConstIter begin,
                     OptionBufferConstIter end) {
    data_ = OptionBuffer(begin, end);
    // Chop the buffer stored in data_ into set of sub buffers.
    createBuffers(data_);
}

uint16_t
OptionCustom::len() {
    // The length of the option is a sum of option header ...
    int length = getHeaderLen();

    // ... lengths of all buffers that hold option data ...
    for (std::vector<OptionBuffer>::const_iterator buf = buffers_.begin();
         buf != buffers_.end(); ++buf) {
        length += buf->size();
    }

    // ... and lengths of all suboptions
    for (OptionCustom::OptionCollection::iterator it = options_.begin();
         it != options_.end();
         ++it) {
        length += (*it).second->len();
    }

    return (length);
}

void OptionCustom::setData(const OptionBufferConstIter first,
                     const OptionBufferConstIter last) {
    // We will copy entire option buffer, so we have to resize data_.
    data_.resize(std::distance(first, last));
    std::copy(first, last, data_.begin());

    // Chop the data_ buffer into set of buffers that represent
    // option fields data.
    createBuffers(data_);
}

std::string OptionCustom::toText(int indent) {
    std::stringstream tmp;

    for (int i = 0; i < indent; ++i)
        tmp << " ";

    tmp << "type=" << type_ << ", len=" << len()-getHeaderLen()
        << ", data fields:" << std::endl;

    OptionDataType data_type = definition_.getType();
    if (data_type == OPT_RECORD_TYPE) {
        const OptionDefinition::RecordFieldsCollection& fields =
            definition_.getRecordFields();

        // For record types we iterate over fields defined in
        // option definition and match the appropriate buffer
        // with them.
        for (OptionDefinition::RecordFieldsConstIter field = fields.begin();
             field != fields.end(); ++field) {
            for (int j = 0; j < indent + 2; ++j) {
                tmp << " ";
            }
            tmp << "#" << std::distance(fields.begin(), field) << " "
                << dataFieldToText(*field, std::distance(fields.begin(),
                                                         field))
                << std::endl;
        }
    } else {
        // For non-record types we iterate over all buffers
        // and print the data type set globally for an option
        // definition. We take the same code path for arrays
        // and non-arrays as they only differ in such a way that
        // non-arrays have just single data field.
        for (unsigned int i = 0; i < getDataFieldsNum(); ++i) {
            for (int j = 0; j < indent + 2; ++j) {
                tmp << " ";
            }
            tmp << "#" << i << " "
                << dataFieldToText(definition_.getType(), i)
                << std::endl;
        }
    }

    // print suboptions
    for (OptionCollection::const_iterator opt = options_.begin();
         opt != options_.end();
         ++opt) {
        tmp << (*opt).second->toText(indent+2);
    }
    return tmp.str();
}

} // end of isc::dhcp namespace
} // end of isc namespace