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+// Copyright (C) 2010 Internet Systems Consortium, Inc. ("ISC")
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+//
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+// Permission to use, copy, modify, and/or distribute this software for any
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+// purpose with or without fee is hereby granted, provided that the above
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+// copyright notice and this permission notice appear in all copies.
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+//
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+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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+// AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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+// PERFORMANCE OF THIS SOFTWARE.
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+
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+// $Id$
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+
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+#include <stdint.h>
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+#include <cassert>
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+#include <iterator>
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+#include <string>
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+#include <vector>
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+
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+#include <boost/archive/iterators/base64_from_binary.hpp>
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+#include <boost/archive/iterators/binary_from_base64.hpp>
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+#include <boost/archive/iterators/transform_width.hpp>
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+#include <boost/math/common_factor.hpp>
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+
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+#include <dns/util/base32hex_from_binary.h>
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+#include <dns/util/binary_from_base32hex.h>
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+
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+#include <dns/util/base16_from_binary.h>
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+#include <dns/util/binary_from_base16.h>
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+
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+#include <exceptions/exceptions.h>
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+
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+#include <dns/util/base32hex.h>
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+#include <dns/util/base64.h>
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+
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+using namespace std;
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+using namespace boost::archive::iterators;
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+
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+namespace isc {
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+namespace dns {
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+
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+// In the following anonymous namespace, we provide a generic framework
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+// to encode/decode baseN format. We use the following tools:
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+// - boost base64_from_binary/binary_from_base64: provide mapping table for
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+// base64.
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+// These classes take another iterator (Base) as a template argument, and
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+// their dereference operator (operator*()) first retrieves an input value
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+// from Base via Base::operator* and converts the value using their mapping
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+// table. The converted value is returned as their own operator*.
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+// - base{32hex,16}_from_binary/binary_from_base{32hex,16}: provide mapping
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+// table for base32hex and base16. A straightforward variation of their
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+// base64 counterparts.
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+// - EncodeNormalizer/DecodeNormalizer: supplemental filter handling baseN
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+// padding characters (=)
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+// - boost transform_width: an iterator framework for handling data stream
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+// per bit-group. It takes another iterator (Base) and output/input bit
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+// numbers (BitsOut/BitsIn) template arguments. A transform_width object
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+// internally maintains a bit stream, which can be retrieved per BitsOut
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+// bits via its dereference operator (operator*()). It builds the stream
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+// by internally iterating over the Base object via Base::operator++ and
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+// Base::operator*, using the least BitsIn bits of the result of
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+// Base::operator*. In our usage BitsIn for encoding and BitsOut for
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+// decoding are always 8 (# of bits for one byte).
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+//
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+// Its dereference operator
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+// retrieves BitsIn bits from the result of "*Base" (if necessary it
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+// internally calls ++Base)
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+//
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+// A conceptual description of how the encoding and decoding work is as
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+// follows:
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+// Encoding:
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+// input binary data => Normalizer (append sufficient number of 0 bits)
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+// => transform_width (extract bit groups from the original
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+// stream)
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+// => baseXX_from_binary (convert each bit group to an
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+// encoded byte using the mapping)
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+// Decoding:
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+// input baseXX text => Normalizer (convert '='s to the encoded characters
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+// corresponding to 0, e.g. 'A's in base64)
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+// => binary_from_baseXX (convert each encoded byte into
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+// the original group bit)
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+// => transform_width (build original byte stream by
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+// concatenating the decoded bit
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+// stream)
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+//
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+// Below, we define a set of templated classes to handle different parameters
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+// for different encoding algorithms.
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+namespace {
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+// Common constants used for all baseN encoding.
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+const char BASE_PADDING_CHAR = '=';
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+const uint8_t BINARY_ZERO_CODE = 0;
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+
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+// EncodeNormalizer is an input iterator intended to be used as a filter
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+// between the binary stream and baseXX_from_binary translator (via
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+// transform_width). An EncodeNormalizer object is configured with two
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+// iterators (base and base_end), specifying the head and end of the input
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+// stream. It internally iterators over the original stream, and return
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+// each byte of the stream intact via its dereference operator until it
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+// reaches the end of the stream. After that the EncodeNormalizer object
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+// will return 0 no matter how many times it is subsequently incremented.
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+// This is necessary because the input binary stream may not contain
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+// sufficient bits for a full encoded text while baseXX_from_binary expects
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+// a sufficient length of input.
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+// Note: this class is intended to be used within this implementation file,
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+// and assumes "base < base_end" on construction without validating the
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+// arguments. The behavior is undefined if this assumption doesn't hold.
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+class EncodeNormalizer : public iterator<input_iterator_tag, uint8_t> {
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+public:
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+ EncodeNormalizer(const vector<uint8_t>::const_iterator& base,
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+ const vector<uint8_t>::const_iterator& base_end) :
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+ base_(base), base_end_(base_end), in_pad_(false)
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+ {}
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+ EncodeNormalizer& operator++() {
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+ if (!in_pad_) {
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+ ++base_;
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+ }
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+ if (base_ == base_end_) {
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+ in_pad_ = true;
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+ }
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+ return (*this);
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+ }
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+ const uint8_t& operator*() const {
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+ if (in_pad_) {
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+ return (BINARY_ZERO_CODE);
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+ } else {
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+ return (*base_);
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+ }
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+ }
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+ bool operator==(const EncodeNormalizer& other) const {
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+ return (base_ == other.base_);
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+ }
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+private:
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+ vector<uint8_t>::const_iterator base_;
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+ const vector<uint8_t>::const_iterator base_end_;
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+ bool in_pad_;
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+};
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+
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+// DecodeNormalizer is an input iterator intended to be used as a filter
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+// between the encoded baseX stream and binary_from_baseXX.
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+// A DecodeNormalizer object is configured with three string iterators
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+// (base, base_beinpad, and base_beginpad), specifying the head of the string,
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+// the beginning position of baseX padding (when there's padding), and
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+// end of the string, respectively. It internally iterators over the original
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+// stream, and return each character of the encoded string via its dereference
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+// operator until it reaches base_beginpad. After that the DecodeNormalizer
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+// will return the encoding character corresponding to the all-0 value
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+// (which is specified on construction via base_zero_code. see also
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+// BaseZeroCode below). This translation is necessary because
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+// binary_from_baseXX doesn't accept the padding character (i.e. '=').
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+// Note: this class is intended to be used within this implementation file,
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+// and for simplicity assumes "base < base_beginpad <= base_end" on
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+// construction without validating the arguments. The behavior is undefined
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+// if this assumption doesn't hold.
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+class DecodeNormalizer : public iterator<input_iterator_tag, char> {
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+public:
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+ DecodeNormalizer(const char base_zero_code,
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+ const string::const_iterator& base,
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+ const string::const_iterator& base_beginpad,
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+ const string::const_iterator& base_end) :
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+ base_zero_code_(base_zero_code),
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+ base_(base), base_beginpad_(base_beginpad), base_end_(base_end),
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+ in_pad_(false)
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+ {}
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+ DecodeNormalizer& operator++() {
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+ ++base_;
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+ while (base_ != base_end_ && isspace(*base_)) {
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+ ++base_;
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+ }
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+ if (base_ == base_beginpad_) {
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+ in_pad_ = true;
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+ }
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+ return (*this);
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+ }
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+ const char& operator*() const {
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+ if (in_pad_ && *base_ == BASE_PADDING_CHAR) {
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+ return (base_zero_code_);
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+ } else {
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+ return (*base_);
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+ }
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+ }
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+ bool operator==(const DecodeNormalizer& other) const {
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+ return (base_ == other.base_);
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+ }
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+private:
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+ const char base_zero_code_;
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+ string::const_iterator base_;
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+ const string::const_iterator base_beginpad_;
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+ const string::const_iterator base_end_;
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+ bool in_pad_;
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+};
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+
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+// BitsPerChunk: number of bits to be converted using the baseN mapping table.
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+// e.g. 6 for base64.
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+// BaseZeroCode: the byte character that represents a value of 0 in
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+// the corresponding encoding. e.g. 'A' for base64.
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+// Encoder: baseX_from_binary<transform_width<EncodeNormalizer,
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+// BitsPerChunk, 8> >
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+// Decoder: transform_width<binary_from_baseX<DecodeNormalizer>,
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+// 8, BitsPerChunk>
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+template <int BitsPerChunk, char BaseZeroCode,
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+ typename Encoder, typename Decoder>
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+struct BaseNTransformer {
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+ static string encode(const vector<uint8_t>& binary);
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+ static void decode(const char* algorithm,
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+ const string& base64, vector<uint8_t>& result);
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+
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+ // BITS_PER_GROUP is the number of bits for the smallest possible (non
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+ // empty) bit string that can be converted to a valid baseN encoded text
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+ // without padding. It's the least common multiple of 8 and BitsPerChunk,
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+ // e.g. 24 for base64.
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+ static const int BITS_PER_GROUP =
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+ boost::math::static_lcm<BitsPerChunk, 8>::value;
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+
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+ // MAX_PADDING_CHARS is the maximum number of padding characters
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+ // that can appear in a valid baseN encoded text.
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+ // It's group_len - chars_for_byte, where group_len is the number of
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+ // encoded characters to represent BITS_PER_GROUP bits, and
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+ // chars_for_byte is the number of encoded character that is needed to
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+ // represent a single byte, which is ceil(8 / BitsPerChunk).
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+ // For example, for base64 we need two encoded characters to represent a
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+ // byte, and each group consists of 4 encoded characters, so
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+ // MAX_PADDING_CHARS is 4 - 2 = 2.
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+ static const int MAX_PADDING_CHARS =
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+ BITS_PER_GROUP / BitsPerChunk -
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+ (8 / BitsPerChunk + ((8 % BitsPerChunk) == 0 ? 0 : 1));
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+};
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+
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+template <int BitsPerChunk, char BaseZeroCode,
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+ typename Encoder, typename Decoder>
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+string
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+BaseNTransformer<BitsPerChunk, BaseZeroCode, Encoder, Decoder>::encode(
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+ const vector<uint8_t>& binary)
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+{
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+ // calculate the resulting length.
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+ size_t bits = binary.size() * 8;
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+ if (bits % BITS_PER_GROUP > 0) {
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+ bits += (BITS_PER_GROUP - (bits % BITS_PER_GROUP));
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+ }
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+ const size_t len = bits / BitsPerChunk;
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+
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+ string result;
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+ result.reserve(len);
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+ result.assign(Encoder(EncodeNormalizer(binary.begin(), binary.end())),
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+ Encoder(EncodeNormalizer(binary.end(), binary.end())));
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+ assert(len >= result.length());
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+ result.append(len - result.length(), BASE_PADDING_CHAR);
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+ return (result);
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+}
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+
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+template <int BitsPerChunk, char BaseZeroCode,
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+ typename Encoder, typename Decoder>
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+void
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+BaseNTransformer<BitsPerChunk, BaseZeroCode, Encoder, Decoder>::decode(
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+ const char* const algorithm,
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+ const string& input,
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+ vector<uint8_t>& result)
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+{
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+ // enumerate the number of trailing padding characters (=), ignoring
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+ // white spaces. since baseN_from_binary doesn't accept padding,
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+ // we handle it explicitly.
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+ size_t padchars = 0;
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+ string::const_reverse_iterator srit = input.rbegin();
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+ string::const_reverse_iterator srit_end = input.rend();
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+ while (srit != srit_end) {
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+ char ch = *srit;
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+ if (ch == BASE_PADDING_CHAR) {
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+ if (++padchars > MAX_PADDING_CHARS) {
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+ isc_throw(BadValue, "Too many " << algorithm
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+ << " padding characters: " << input);
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+ }
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+ } else if (!isspace(ch)) {
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+ break;
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+ }
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+ ++srit;
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+ }
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+ // then calculate the number of padding bits corresponding to the padding
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+ // characters. In general, the padding bits consist of all-zero
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+ // trailing bits of the last encoded character followed by zero bits
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+ // represented by the padding characters:
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+ // 1st pad 2nd pad 3rd pad...
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+ // +++===== ======= ===... (+: from encoded chars, =: from pad chars)
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+ // 0000...0 0......0 000...
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+ // 0 7 8 15 16.... (bits)
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+ // The number of bits for the '==...' part is padchars * BitsPerChunk.
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+ // So the total number of padding bits is the smallest multiple of 8
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+ // that is >= padchars * BitsPerChunk.
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+ // (Below, note the common idiom of the bitwise AND with ~7. It clears the
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+ // lowest three bits, so has the effect of rounding the result down to the
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+ // nearest multiple of 8)
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+ const size_t padbits = (padchars * BitsPerChunk + 7) & ~7;
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+
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+ // In some encoding algorithm, it could happen that a padding byte would
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+ // contain a full set of encoded bits, which is not allowed by definition
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+ // of padding. For example, if BitsPerChunk is 5, the following
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+ // representation could happen:
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+ // ++00000= (+: from encoded chars, 0: encoded char for '0', =: pad chars)
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+ // 0 7 (bits)
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+ // This must actually be encoded as follows:
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+ // ++======
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+ // 0 7 (bits)
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+ // The following check rejects this type of invalid encoding.
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+ if (padbits > BitsPerChunk * (padchars + 1)) {
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+ isc_throw(BadValue, "Invalid " << algorithm << "padding: " << input);
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+ }
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+
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+ // convert the number of bits in bytes for convenience.
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+ const size_t padbytes = padbits / 8;
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+
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+ try {
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+ result.assign(Decoder(DecodeNormalizer(BaseZeroCode, input.begin(),
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+ srit.base(), input.end())),
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+ Decoder(DecodeNormalizer(BaseZeroCode, input.end(),
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+ input.end(), input.end())));
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+ } catch (const dataflow_exception& ex) {
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+ // convert any boost exceptions into our local one.
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+ isc_throw(BadValue, ex.what());
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+ }
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+
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+ // Confirm the original BaseX text is the canonical encoding of the
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+ // data, that is, that the first byte of padding is indeed 0.
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+ // (DecodeNormalizer and binary_from_baseXX ensure that the rest of the
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+ // padding is all zero).
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+ assert(result.size() >= padbytes);
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+ if (padbytes > 0 && *(result.end() - padbytes) != 0) {
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+ isc_throw(BadValue, "Non 0 bits included in " << algorithm
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+ << " padding: " << input);
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+ }
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+
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+ // strip the padded zero-bit fields
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+ result.resize(result.size() - padbytes);
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+}
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+
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+//
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+// Instantiation for BASE-64
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+//
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+typedef
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+base64_from_binary<transform_width<EncodeNormalizer, 6, 8> > base64_encoder;
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+typedef
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+transform_width<binary_from_base64<DecodeNormalizer>, 8, 6> base64_decoder;
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+typedef BaseNTransformer<6, 'A', base64_encoder, base64_decoder>
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+Base64Transformer;
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+
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+//
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+// Instantiation for BASE-32HEX
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+//
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+typedef
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+base32hex_from_binary<transform_width<EncodeNormalizer, 5, 8> >
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+base32hex_encoder;
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+typedef
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+transform_width<binary_from_base32hex<DecodeNormalizer>, 8, 5>
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+base32hex_decoder;
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+typedef BaseNTransformer<5, '0', base32hex_encoder, base32hex_decoder>
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+Base32HexTransformer;
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+
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+//
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+// Instantiation for BASE-16 (HEX)
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+//
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+typedef
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+base16_from_binary<transform_width<EncodeNormalizer, 4, 8> > base16_encoder;
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+typedef
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+transform_width<binary_from_base16<DecodeNormalizer>, 8, 4> base16_decoder;
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+typedef BaseNTransformer<4, '0', base16_encoder, base16_decoder>
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+Base16Transformer;
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+}
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+
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+string
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+encodeBase64(const vector<uint8_t>& binary) {
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+ return (Base64Transformer::encode(binary));
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+}
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+
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+void
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+decodeBase64(const string& input, vector<uint8_t>& result) {
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+ Base64Transformer::decode("base64", input, result);
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+}
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+
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+string
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+encodeBase32Hex(const vector<uint8_t>& binary) {
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+ return (Base32HexTransformer::encode(binary));
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+}
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+
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|
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+void
|
|
|
+decodeBase32Hex(const string& input, vector<uint8_t>& result) {
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+ Base32HexTransformer::decode("base32hex", input, result);
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|
+}
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+
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|
+string
|
|
|
+encodeHex(const vector<uint8_t>& binary) {
|
|
|
+ return (Base16Transformer::encode(binary));
|
|
|
+}
|
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+
|
|
|
+void
|
|
|
+decodeHex(const string& input, vector<uint8_t>& result) {
|
|
|
+ Base16Transformer::decode("base16", input, result);
|
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|
+}
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+
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+}
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+}
|