164 lines
3.6 KiB
C++
164 lines
3.6 KiB
C++
// The Construct
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//
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// Copyright (C) The Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
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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 is present in all copies. The
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// full license for this software is available in the LICENSE file.
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namespace ircd::b58
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{
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[[gnu::visibility("internal")]]
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extern const string_view dict;
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static thread_local char conv_tmp_buf[64_KiB];
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}
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decltype(ircd::b58::dict)
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ircd::b58::dict
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{
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"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"_sv
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};
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//
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// Conversion convenience suite
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//
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ircd::string_view
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ircd::b58::fromb64(const mutable_buffer &out,
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const string_view &in)
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{
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if(unlikely(b64::decode_size(in) > size(conv_tmp_buf)))
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throw error
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{
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"String too large for conversion at this time."
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};
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return b58::encode(out, b64::decode(conv_tmp_buf, in));
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}
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ircd::string_view
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ircd::b58::tob64_unpadded(const mutable_buffer &out,
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const string_view &in)
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{
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if(unlikely(b58::decode_size(in) > size(conv_tmp_buf)))
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throw error
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{
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"String too large for conversion at this time."
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};
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return b64::encode_unpadded(out, b58::decode(conv_tmp_buf, in));
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}
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ircd::string_view
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ircd::b58::tob64(const mutable_buffer &out,
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const string_view &in)
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{
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if(unlikely(b58::decode_size(in) > size(conv_tmp_buf)))
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throw error
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{
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"String too large for conversion at this time."
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};
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return b64::encode(out, b58::decode(conv_tmp_buf, in));
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}
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//
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// Base58 decode
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//
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ircd::const_buffer
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ircd::b58::decode(const mutable_buffer &buf,
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const string_view &in)
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{
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auto p(begin(in));
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size_t zeroes(0);
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for(; p != end(in) && *p == '1'; ++p)
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++zeroes;
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const mutable_buffer out
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{
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data(buf) + zeroes, std::min(b58::decode_size(in), size(buf) - zeroes)
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};
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assert(size(out) + zeroes <= size(buf));
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memset(data(out), 0, size(out));
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size_t length(0);
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for(size_t i(0); p != end(in); ++p, length = i, i = 0)
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{
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auto carry(dict.find(*p));
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if(unlikely(carry == std::string::npos))
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throw std::out_of_range
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{
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"Invalid base58 character"
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};
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for(auto it(rbegin(out)); (carry || i < length) && it != rend(out); ++it, i++)
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{
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carry += 58 * (*it);
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*it = carry % 256;
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carry /= 256;
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}
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}
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auto it(begin(buf));
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assert(it + zeroes + length <= end(buf));
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for(; it != end(buf) && zeroes; *it++ = 0, --zeroes);
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memmove(it, data(out) + (size(out) - length), length);
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return const_buffer
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{
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begin(buf), it + length
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};
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}
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//
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// Base58 encode
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//
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ircd::string_view
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ircd::b58::encode(const mutable_buffer &buf,
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const const_buffer &in)
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noexcept
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{
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auto p(begin(in));
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size_t zeroes(0);
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for(; p != end(in) && *p == 0; ++p)
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++zeroes;
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const mutable_buffer out
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{
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data(buf) + zeroes, std::min(b58::encode_size(in), size(buf) - zeroes)
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};
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assert(size(out) + zeroes <= size(buf));
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memset(data(out), 0, size(out));
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size_t length(0);
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for(size_t i(0); p != end(in); ++p, length = i, i = 0)
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{
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size_t carry(*p);
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for(auto it(rbegin(out)); (carry || i < length) && it != rend(out); ++it, i++)
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{
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carry += 256 * (*it);
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*it = carry % 58;
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carry /= 58;
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}
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}
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auto it(begin(buf));
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assert(it + zeroes + length <= end(buf));
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for(; it != end(buf) && zeroes; *it++ = '1', --zeroes);
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memmove(it, data(out) + (size(out) - length), length);
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return string_view
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{
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begin(buf), std::transform(it, it + length, it, []
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(const uint8_t &in)
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{
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return dict.at(in);
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})
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};
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}
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