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// Copyright (C) 2010 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.
// $Id$
#include <stdint.h>
#include <cassert>
#include <iterator>
#include <string>
#include <vector>
#include <boost/archive/iterators/base64_from_binary.hpp>
#include <boost/archive/iterators/binary_from_base64.hpp>
#include <boost/archive/iterators/transform_width.hpp>
#include <exceptions/exceptions.h>
#include <dns/base64.h>
using namespace std;
using namespace boost::archive::iterators;
namespace isc {
namespace dns {
namespace {
const char BASE64_PADDING_CHAR = '=';
const uint8_t BINARY_ZERO_CODE = 0;
class BinaryNormalizer : public iterator<input_iterator_tag, uint8_t> {
public:
BinaryNormalizer(const vector<uint8_t>::const_iterator& base,
const vector<uint8_t>::const_iterator& base_end) :
base_(base), base_end_(base_end), in_pad_(false)
{}
BinaryNormalizer& operator++()
{
if (!in_pad_) {
++base_;
}
if (base_ == base_end_) {
in_pad_ = true;
}
return (*this);
}
const uint8_t& operator*() const {
if (in_pad_) {
return (BINARY_ZERO_CODE);
} else {
return (*base_);
}
}
bool operator==(const BinaryNormalizer& other) const
{
return (base_ == other.base_);
}
private:
vector<uint8_t>::const_iterator base_;
const vector<uint8_t>::const_iterator base_end_;
bool in_pad_;
};
typedef
base64_from_binary<transform_width<BinaryNormalizer, 6, 8> > base64_encoder;
} // end of anonymous namespace
string
encodeBase64(const vector<uint8_t>& binary)
{
// calculate the resulting length. it's the smallest multiple of 4
// equal to or larger than 4/3 * original data length.
size_t len = ((binary.size() * 4 / 3) + 3) & ~3;
string base64;
base64.reserve(len);
base64.assign(base64_encoder(BinaryNormalizer(binary.begin(),
binary.end())),
base64_encoder(BinaryNormalizer(binary.end(), binary.end())));
assert(len >= base64.length());
base64.append(len - base64.length(), BASE64_PADDING_CHAR);
return (base64);
}
namespace {
const size_t BASE64_MAX_PADDING_CHARS = 2;
const char BASE64_ZERO_CODE = 'A'; // correspond to 000000(2)
class Base64Normalizer : public iterator<input_iterator_tag, char> {
public:
Base64Normalizer(const string::const_iterator& base,
const string::const_iterator& base_beginpad,
const string::const_iterator& base_end) :
base_(base), base_beginpad_(base_beginpad), base_end_(base_end),
in_pad_(false)
{}
Base64Normalizer& operator++()
{
++base_;
while (base_ != base_end_ && isspace(*base_)) {
++base_;
}
if (base_ == base_beginpad_) {
in_pad_ = true;
}
return (*this);
}
const char& operator*() const {
if (in_pad_ && *base_ == BASE64_PADDING_CHAR) {
return (BASE64_ZERO_CODE);
} else {
return (*base_);
}
}
bool operator==(const Base64Normalizer& other) const
{
return (base_ == other.base_);
}
private:
string::const_iterator base_;
const string::const_iterator base_beginpad_;
const string::const_iterator base_end_;
bool in_pad_;
};
typedef
transform_width<binary_from_base64<Base64Normalizer, char>, 8, 6, char>
base64_decoder;
} // end of anonymous namespace
void
decodeBase64(const string& base64, vector<uint8_t>& result)
{
// enumerate the number of trailing padding characters (=), ignoring
// white spaces. since base64_from_binary doesn't accept padding,
// we handle it explicitly.
size_t padlen = 0;
string::const_reverse_iterator srit = base64.rbegin();
string::const_reverse_iterator srit_end = base64.rend();
while (srit != srit_end) {
char ch = *srit;
if (ch == BASE64_PADDING_CHAR) {
if (++padlen > BASE64_MAX_PADDING_CHARS) {
isc_throw(BadBase64String,
"Too many Base64 padding characters");
}
} else if (!isspace(ch)) {
break;
}
++srit;
}
try {
result.assign(base64_decoder(Base64Normalizer(base64.begin(),
srit.base(),
base64.end())),
base64_decoder(Base64Normalizer(base64.end(),
base64.end(),
base64.end())));
} catch (dataflow_exception& ex) {
isc_throw(BadBase64String, ex.what());
}
// Confirm the original base64 text is the canonical encoding of the
// data.
assert(result.size() >= padlen);
vector<uint8_t>::const_reverse_iterator rit = result.rbegin();
for (int i = 0; i < padlen; ++i, ++rit) {
if (*rit != 0) {
isc_throw(BadBase64String, "Non 0 bits included in padding");
}
}
// strip the padded zero-bit fields
result.resize(result.size() - padlen);
}
}
}
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