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| -rw-r--r-- | src/lib/dhcp/option6_iaprefix.h | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/src/lib/dhcp/option6_iaprefix.h b/src/lib/dhcp/option6_iaprefix.h new file mode 100644 index 0000000..3d9a7f2 --- /dev/null +++ b/src/lib/dhcp/option6_iaprefix.h @@ -0,0 +1,148 @@ +// Copyright (C) 2013-2022 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 OPTION6_IAPREFIX_H +#define OPTION6_IAPREFIX_H + +#include <asiolink/io_address.h> +#include <dhcp/option6_iaaddr.h> +#include <dhcp/option.h> + +namespace isc { +namespace dhcp { + + +/// @brief Class that represents IAPREFIX option in DHCPv6 +/// +/// It is based on a similar class that handles addresses. There are major +/// differences, though. The fields are in different order. There is also +/// additional prefix length field. +/// +/// It should be noted that to get a full prefix (2 values: base prefix, and +/// a prefix length) 2 methods are used: getAddress() and getLength(). Although +/// using getAddress() to obtain base prefix is somewhat counter-intuitive at +/// first, it becomes obvious when one realizes that an address is a special +/// case of a prefix with /128. It makes everyone's life much easier, because +/// the base prefix doubles as a regular address in many cases, e.g. when +/// searching for a lease. +/// +/// When searching for a prefix in the database or simply comparing two prefixes +/// for equality, it is important that only the significant parts of the +/// prefixes are compared. It is possible that the client or a server sends a +/// prefix which has non-significant bits (beyond prefix length) set. The +/// server or client receiving such a prefix should be liberal and not discard +/// this prefix. It should rather ignore the non-significant bits. Therefore +/// the unpack() function, which parses the prefix from the wire, always sets +/// the non-significant bits to 0 so as two prefixes received on the wire can +/// be compared without additional processing. +/// +/// @todo Currently, the constructor which creates the option from the textual +/// format doesn't set non-significant bits to 0. This is because it is assumed +/// that the prefixes from the string are created locally (not received over the +/// wire) and should be validated before the option is created. If we wanted +/// to set non-significant bits to 0 when the prefix is created from the textual +/// format it would have some performance implications, because the option would +/// need to be turned into wire format, appropriate bits set to 0 and then +/// option would need to be created again from the wire format. We may consider +/// doing it if we find a use case where it is required. +class Option6IAPrefix : public Option6IAAddr { + +public: + /// length of the fixed part of the IAPREFIX option + static const size_t OPTION6_IAPREFIX_LEN = 25; + + /// @brief Constructor, used for options constructed (during transmission). + /// + /// @param type option type + /// @param addr reference to an address + /// @param prefix_length length (1-128) + /// @param preferred address preferred lifetime (in seconds) + /// @param valid address valid lifetime (in seconds) + Option6IAPrefix(uint16_t type, const isc::asiolink::IOAddress& addr, + uint8_t prefix_length, uint32_t preferred, uint32_t valid); + + /// @brief Constructor, used for received options. + /// + /// @throw OutOfRange if buffer is too short + /// + /// @param type option type + /// @param begin iterator to first byte of option data + /// @param end iterator to end of option data (first byte after option end) + Option6IAPrefix(uint32_t type, OptionBuffer::const_iterator begin, + OptionBuffer::const_iterator end); + + /// @brief Copies this option and returns a pointer to the copy. + virtual OptionPtr clone() const; + + /// @brief Writes option in wire-format. + /// + /// Writes option in wire-format to buf, returns pointer to first unused + /// byte after stored option. + /// + /// @throw BadValue if the address is not IPv6 + /// + /// @param buf pointer to a buffer + /// @param check if set to false, allows options larger than 255 for v4 + void pack(isc::util::OutputBuffer& buf, bool check = true) const; + + /// @brief Parses received buffer. + /// + /// This function calls the @c Option6IAPrefix::mask function to set the + /// non-significant bits of the prefix (bits beyond the length of the + /// prefix) to zero. See the @c Option6IAPrefix class documentation for + /// details why it is done. + /// + /// @throw OutOfRange when buffer is shorter than 25 bytes + /// + /// @param begin iterator to first byte of option data + /// @param end iterator to end of option data (first byte after option end) + virtual void unpack(OptionBufferConstIter begin, + OptionBufferConstIter end); + + /// Returns string representation of the option. + /// + /// @param indent number of spaces before printing text + /// + /// @return string with text representation. + virtual std::string toText(int indent = 0) const; + + /// sets address in this option. + /// + /// @param prefix prefix to be sent in this option + /// @param length prefix length + void setPrefix(const isc::asiolink::IOAddress& prefix, + uint8_t length) { addr_ = prefix; prefix_len_ = length; } + + uint8_t getLength() const { return prefix_len_; } + + /// returns data length (data length + DHCPv4/DHCPv6 option header) + virtual uint16_t len() const; + +private: + + /// @brief Apply mask of the specific length to the IPv6 address. + /// + /// @param begin Iterator pointing to the buffer holding IPv6 address. + /// @param end Iterator pointing to the end of the buffer holding IPv6 + /// address. + /// @param len Length of the mask to be applied. + /// @param [out] output_address Reference to the buffer where the address + /// with a mask applied is output. + void mask(OptionBuffer::const_iterator begin, + OptionBuffer::const_iterator end, + const uint8_t len, + OptionBuffer& output_address) const; + + uint8_t prefix_len_; +}; + +/// @brief Pointer to the @c Option6IAPrefix object. +typedef boost::shared_ptr<Option6IAPrefix> Option6IAPrefixPtr; + +} // isc::dhcp namespace +} // isc namespace + +#endif // OPTION_IAPREFIX_H |