This is a simple gem that helps decoding and encoding transactions input data for EVM based blockchains like Ethereum and Tron.

Run

gem install evm-tx-input-decoder

or add

gem 'evm-tx-input-decoder', require: 'evm_tx_input'

to your Gemfile.

Let's consider decoding process by example USDT transaction in an Ethereum blockchain.

The input data is 0xa9059cbb00000000000000000000000003cb76e200ba785f6008c12933aa3640536d2011000000000000000000000000000000000000000000000000000000a083712e00, which can be found in More details section.

The USDT token ABI can be found by this url

require 'open-uri'
require 'evm_tx_input'

json = URI.open('http://api.etherscan.io/api?module=contract&action=getabi&address=0xdac17f958d2ee523a2206206994597c13d831ec7&format=raw') { |file| file.read }
abi = JSON.parse(json)
input = '0xa9059cbb00000000000000000000000003cb76e200ba785f6008c12933aa3640536d2011000000000000000000000000000000000000000000000000000000a083712e00'

function = EvmTxInput::Decoder.new(abi).decode_input(input)
function.id #=> "a9059cbb"
function.name #=> "transfer"
function.arguments
# [#<EvmTxInput::Argument:0x00000001107ffa60 @name="_to", @type="address", @value="0x03cb76e200ba785f6008c12933aa3640536d2011">,
#  #<EvmTxInput::Argument:0x00000001107ffa10 @name="_value", @type="uint256", @value=689400000000>]

Following decoding procedure let's encode the previous result.

require 'evm_tx_input'

function_name = 'transfer'
types = %w[address uint256]
args = ['0x03cb76e200ba785f6008c12933aa3640536d2011', 689400000000]
EvmTxInput::Encoder.encode_input(function_name, types, args)
#=> "0xa9059cbb00000000000000000000000003cb76e200ba785f6008c12933aa3640536d2011000000000000000000000000000000000000000000000000000000a083712e00"

For more details read the documentation.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/rkotov93/evm-tx-input-decoder.

The gem is available as open source under the terms of the MIT License.