mirror of https://github.com/oxen-io/oxen-mq.git
222 lines
10 KiB
C++
222 lines
10 KiB
C++
// Copyright (c) 2019-2021, The Oxen Project
|
|
//
|
|
// All rights reserved.
|
|
//
|
|
// Redistribution and use in source and binary forms, with or without modification, are
|
|
// permitted provided that the following conditions are met:
|
|
//
|
|
// 1. Redistributions of source code must retain the above copyright notice, this list of
|
|
// conditions and the following disclaimer.
|
|
//
|
|
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
|
|
// of conditions and the following disclaimer in the documentation and/or other
|
|
// materials provided with the distribution.
|
|
//
|
|
// 3. Neither the name of the copyright holder nor the names of its contributors may be
|
|
// used to endorse or promote products derived from this software without specific
|
|
// prior written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
|
|
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
|
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
|
|
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
|
|
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
#pragma once
|
|
#include <string>
|
|
#include <string_view>
|
|
#include <array>
|
|
#include <iterator>
|
|
#include <cassert>
|
|
#include "byte_type.h"
|
|
|
|
namespace oxenmq {
|
|
|
|
namespace detail {
|
|
|
|
/// Compile-time generated lookup tables for base64 conversion.
|
|
struct b64_table {
|
|
// Store the 0-63 decoded value of every possible char; all the chars that aren't valid are set
|
|
// to 0. (If you don't trust your data, check it with is_base64 first, which uses these 0's
|
|
// to detect invalid characters -- which is why we want a full 256 element array).
|
|
char from_b64_lut[256];
|
|
// Store the encoded character of every 0-63 (6 bit) value.
|
|
char to_b64_lut[64];
|
|
|
|
// constexpr constructor that fills out the above (and should do it at compile time for any half
|
|
// decent compiler).
|
|
constexpr b64_table() noexcept : from_b64_lut{}, to_b64_lut{} {
|
|
for (unsigned char c = 0; c < 26; c++) {
|
|
from_b64_lut[(unsigned char)('A' + c)] = 0 + c;
|
|
to_b64_lut[ (unsigned char)( 0 + c)] = 'A' + c;
|
|
}
|
|
for (unsigned char c = 0; c < 26; c++) {
|
|
from_b64_lut[(unsigned char)('a' + c)] = 26 + c;
|
|
to_b64_lut[ (unsigned char)(26 + c)] = 'a' + c;
|
|
}
|
|
for (unsigned char c = 0; c < 10; c++) {
|
|
from_b64_lut[(unsigned char)('0' + c)] = 52 + c;
|
|
to_b64_lut[ (unsigned char)(52 + c)] = '0' + c;
|
|
}
|
|
to_b64_lut[62] = '+'; from_b64_lut[(unsigned char) '+'] = 62;
|
|
to_b64_lut[63] = '/'; from_b64_lut[(unsigned char) '/'] = 63;
|
|
}
|
|
// Convert a b64 encoded character into a 0-63 value
|
|
constexpr char from_b64(unsigned char c) const noexcept { return from_b64_lut[c]; }
|
|
// Convert a 0-31 value into a b64 encoded character
|
|
constexpr char to_b64(unsigned char b) const noexcept { return to_b64_lut[b]; }
|
|
} constexpr b64_lut;
|
|
|
|
// This main point of this static assert is to force the compiler to compile-time build the constexpr tables.
|
|
static_assert(b64_lut.from_b64('/') == 63 && b64_lut.from_b64('7') == 59 && b64_lut.to_b64(38) == 'm', "");
|
|
|
|
} // namespace detail
|
|
|
|
/// Converts bytes into a base64 encoded character sequence.
|
|
template <typename InputIt, typename OutputIt>
|
|
void to_base64(InputIt begin, InputIt end, OutputIt out) {
|
|
static_assert(sizeof(decltype(*begin)) == 1, "to_base64 requires chars/bytes");
|
|
int bits = 0; // Tracks the number of unconsumed bits held in r, will always be in {0, 2, 4}
|
|
std::uint_fast16_t r = 0;
|
|
while (begin != end) {
|
|
r = r << 8 | static_cast<unsigned char>(*begin++);
|
|
|
|
// we just added 8 bits, so we can *always* consume 6 to produce one character, so (net) we
|
|
// are adding 2 bits.
|
|
bits += 2;
|
|
*out++ = detail::b64_lut.to_b64(r >> bits); // Right-shift off the bits we aren't consuming right now
|
|
|
|
// Drop the bits we don't want to keep (because we just consumed them)
|
|
r &= (1 << bits) - 1;
|
|
|
|
if (bits == 6) { // We have enough bits to produce a second character (which means we had 4 before and added 8)
|
|
bits = 0;
|
|
*out++ = detail::b64_lut.to_b64(r);
|
|
r = 0;
|
|
}
|
|
}
|
|
|
|
// If bits == 0 then we ended our 6-bit outputs coinciding with 8-bit values, i.e. at a multiple
|
|
// of 24 bits: this means we don't have anything else to output and don't need any padding.
|
|
if (bits == 2) {
|
|
// We finished with 2 unconsumed bits, which means we ended 1 byte past a 24-bit group (e.g.
|
|
// 1 byte, 4 bytes, 301 bytes, etc.); since we need to always be a multiple of 4 output
|
|
// characters that means we've produced 1: so we right-fill 0s to get the next char, then
|
|
// add two padding ='s.
|
|
*out++ = detail::b64_lut.to_b64(r << 4);
|
|
*out++ = '=';
|
|
*out++ = '=';
|
|
} else if (bits == 4) {
|
|
// 4 bits left means we produced 2 6-bit values from the first 2 bytes of a 3-byte group.
|
|
// Fill 0s to get the last one, plus one padding output.
|
|
*out++ = detail::b64_lut.to_b64(r << 2);
|
|
*out++ = '=';
|
|
}
|
|
}
|
|
|
|
/// Creates and returns a base64 string from an iterator pair of a character sequence
|
|
template <typename It>
|
|
std::string to_base64(It begin, It end) {
|
|
std::string base64;
|
|
if constexpr (std::is_base_of_v<std::random_access_iterator_tag, typename std::iterator_traits<It>::iterator_category>)
|
|
base64.reserve((std::distance(begin, end) + 2) / 3 * 4); // bytes*4/3, rounded up to the next multiple of 4
|
|
to_base64(begin, end, std::back_inserter(base64));
|
|
return base64;
|
|
}
|
|
|
|
/// Creates a base64 string from an iterable, std::string-like object
|
|
template <typename CharT>
|
|
std::string to_base64(std::basic_string_view<CharT> s) { return to_base64(s.begin(), s.end()); }
|
|
inline std::string to_base64(std::string_view s) { return to_base64<>(s); }
|
|
|
|
/// Returns true if the range is a base64 encoded value; we allow (but do not require) '=' padding,
|
|
/// but only at the end, only 1 or 2, and only if it pads out the total to a multiple of 4.
|
|
template <typename It>
|
|
constexpr bool is_base64(It begin, It end) {
|
|
static_assert(sizeof(decltype(*begin)) == 1, "is_base64 requires chars/bytes");
|
|
using std::distance;
|
|
using std::prev;
|
|
|
|
// Allow 1 or 2 padding chars *if* they pad it to a multiple of 4.
|
|
if (begin != end && distance(begin, end) % 4 == 0) {
|
|
auto last = prev(end);
|
|
if (static_cast<unsigned char>(*last) == '=')
|
|
end = last--;
|
|
if (static_cast<unsigned char>(*last) == '=')
|
|
end = last;
|
|
}
|
|
|
|
for (; begin != end; ++begin) {
|
|
auto c = static_cast<unsigned char>(*begin);
|
|
if (detail::b64_lut.from_b64(c) == 0 && c != 'A')
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Returns true if the string-like value is a base64 encoded value
|
|
template <typename CharT>
|
|
constexpr bool is_base64(std::basic_string_view<CharT> s) { return is_base64(s.begin(), s.end()); }
|
|
constexpr bool is_base64(std::string_view s) { return is_base64(s.begin(), s.end()); }
|
|
|
|
/// Converts a sequence of base64 digits to bytes. Undefined behaviour if any characters are not
|
|
/// valid base64 alphabet characters. It is permitted for the input and output ranges to overlap as
|
|
/// long as `out` is no earlier than `begin`. Trailing padding characters are permitted but not
|
|
/// required.
|
|
///
|
|
/// It is possible to provide "impossible" base64 encoded values; for example "YWJja" which has 30
|
|
/// bits of data even though a base64 encoded byte string should have 24 (4 chars) or 36 (6 chars)
|
|
/// bits for a 3- and 4-byte input, respectively. We ignore any such "impossible" bits, and
|
|
/// similarly ignore impossible bits in the bit "overhang"; that means "YWJjZA==" (the proper
|
|
/// encoding of "abcd") and "YWJjZB", "YWJjZC", ..., "YWJjZP" all decode to the same "abcd" value:
|
|
/// the last 4 bits of the last character are essentially considered padding.
|
|
template <typename InputIt, typename OutputIt>
|
|
void from_base64(InputIt begin, InputIt end, OutputIt out) {
|
|
static_assert(sizeof(decltype(*begin)) == 1, "from_base64 requires chars/bytes");
|
|
uint_fast16_t curr = 0;
|
|
int bits = 0; // number of bits we've loaded into val; we always keep this < 8.
|
|
while (begin != end) {
|
|
auto c = static_cast<unsigned char>(*begin++);
|
|
|
|
// padding; don't bother checking if we're at the end because is_base64 is a precondition
|
|
// and we're allowed UB if it isn't satisfied.
|
|
if (c == '=') continue;
|
|
|
|
curr = curr << 6 | detail::b64_lut.from_b64(c);
|
|
if (bits == 0)
|
|
bits = 6;
|
|
else {
|
|
bits -= 2; // Added 6, removing 8
|
|
*out++ = static_cast<detail::byte_type_t<OutputIt>>(
|
|
static_cast<uint8_t>(curr >> bits));
|
|
curr &= (1 << bits) - 1;
|
|
}
|
|
}
|
|
// Don't worry about leftover bits because either they have to be 0, or they can't happen at
|
|
// all. See base32z.h for why: the reasoning is exactly the same (except using 6 bits per
|
|
// character here instead of 5).
|
|
}
|
|
|
|
/// Converts base64 digits from a iterator pair of characters into a std::string of bytes.
|
|
/// Undefined behaviour if any characters are not valid base64 characters.
|
|
template <typename It>
|
|
std::string from_base64(It begin, It end) {
|
|
std::string bytes;
|
|
if constexpr (std::is_base_of_v<std::random_access_iterator_tag, typename std::iterator_traits<It>::iterator_category>)
|
|
bytes.reserve(std::distance(begin, end)*6 / 8); // each digit carries 6 bits; this may overallocate by 1-2 bytes due to padding
|
|
from_base64(begin, end, std::back_inserter(bytes));
|
|
return bytes;
|
|
}
|
|
|
|
/// Converts base64 digits from a std::string-like object into a std::string of bytes. Undefined
|
|
/// behaviour if any characters are not valid base64 characters.
|
|
template <typename CharT>
|
|
std::string from_base64(std::basic_string_view<CharT> s) { return from_base64(s.begin(), s.end()); }
|
|
inline std::string from_base64(std::string_view s) { return from_base64<>(s); }
|
|
|
|
}
|