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construct/ircd/b58.cc

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