solidity/libdevcore/IpfsHash.cpp
2019-11-26 13:07:42 +01:00

91 lines
2.4 KiB
C++

/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libdevcore/IpfsHash.h>
#include <libdevcore/Assertions.h>
#include <libdevcore/Exceptions.h>
#include <libdevcore/picosha2.h>
#include <libdevcore/CommonData.h>
using namespace std;
using namespace dev;
namespace
{
bytes varintEncoding(size_t _n)
{
bytes encoded;
while (_n > 0x7f)
{
encoded.emplace_back(uint8_t(0x80 | (_n & 0x7f)));
_n >>= 7;
}
encoded.emplace_back(_n);
return encoded;
}
string base58Encode(bytes const& _data)
{
static string const alphabet{"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"};
bigint data(toHex(_data, HexPrefix::Add));
string output;
while (data)
{
output += alphabet[size_t(data % alphabet.size())];
data /= alphabet.size();
}
reverse(output.begin(), output.end());
return output;
}
}
bytes dev::ipfsHash(string _data)
{
assertThrow(_data.length() < 1024 * 256, DataTooLong, "IPFS hash for large (chunked) files not yet implemented.");
bytes lengthAsVarint = varintEncoding(_data.size());
bytes protobufEncodedData;
// Type: File
protobufEncodedData += bytes{0x08, 0x02};
if (!_data.empty())
{
// Data (length delimited bytes)
protobufEncodedData += bytes{0x12};
protobufEncodedData += lengthAsVarint;
protobufEncodedData += asBytes(std::move(_data));
}
// filesize: length as varint
protobufEncodedData += bytes{0x18} + lengthAsVarint;
// PBDag:
// Data: (length delimited bytes)
size_t protobufLength = protobufEncodedData.size();
bytes blockData = bytes{0x0a} + varintEncoding(protobufLength) + std::move(protobufEncodedData);
// TODO Handle "large" files with multiple blocks
// Multihash: sha2-256, 256 bits
bytes hash = bytes{0x12, 0x20} + picosha2::hash256(std::move(blockData));
return hash;
}
string dev::ipfsHashBase58(string _data)
{
return base58Encode(ipfsHash(std::move(_data)));
}