defmodule ABI do
@moduledoc """
Documentation for ABI, the function interface language for Solidity.
Generally, the ABI describes how to take binary Ethereum and transform
it to or from types that Solidity understands.
"""
alias ABI.FunctionSelector
alias ABI.Parser
alias ABI.TypeDecoder
alias ABI.TypeEncoder
alias ABI.Util
@doc """
Encodes the given data into the function signature or tuple signature.
In place of a signature, you can also pass one of the `ABI.FunctionSelector` structs returned from `parse_specification/1`.
## Examples
iex> ABI.encode("baz(uint,address)", [50, <<1::160>> |> :binary.decode_unsigned])
...> |> Base.encode16(case: :lower)
"a291add600000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001"
iex> ABI.encode("(address[])", [{[]}] ) |> Base.encode16(case: :lower)
"000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000"
iex> ABI.encode("baz(uint8)", [9999])
** (RuntimeError) Data overflow encoding uint, data `9999` cannot fit in 8 bits
iex> ABI.encode("(uint,address)", [{50, <<1::160>> |> :binary.decode_unsigned}])
...> |> Base.encode16(case: :lower)
"00000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001"
iex> ABI.encode("(string)", [{"Ether Token"}])
...> |> Base.encode16(case: :lower)
"00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000b457468657220546f6b656e000000000000000000000000000000000000000000"
iex> ABI.encode("test(uint[], uint[])", [[1], [2]])
...> |> Base.encode16(case: :lower)
"f0d7f6eb000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002"
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
...> |> Enum.find(&(&1.function == "bark")) # bark(address,bool)
...> |> ABI.encode([<<1::160>> |> :binary.decode_unsigned, true])
...> |> Base.encode16(case: :lower)
"b85d0bd200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001"
"""
def encode(function_signature, data, data_type \\ :input)
def encode(function_signature, data, data_type) when is_binary(function_signature) do
function_signature
|> Parser.parse!()
|> encode(data, data_type)
end
def encode(%FunctionSelector{} = function_selector, data, data_type) do
TypeEncoder.encode(data, function_selector, data_type)
end
@doc """
Decodes the given data based on the function or tuple
signature.
In place of a signature, you can also pass one of the `ABI.FunctionSelector` structs returned from `parse_specification/1`.
## Examples
iex> ABI.decode("baz(uint,address)", "00000000000000000000000000000000000000000000000000000000000000320000000000000000000000000000000000000000000000000000000000000001" |> Base.decode16!(case: :lower))
[50, <<1::160>>]
iex> ABI.decode("(address[])", "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000" |> Base.decode16!(case: :lower))
[{[]}]
iex> ABI.decode("(string)", "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000b457468657220546f6b656e000000000000000000000000000000000000000000" |> Base.decode16!(case: :lower))
[{"Ether Token"}]
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
...> |> Enum.find(&(&1.function == "bark")) # bark(address,bool)
...> |> ABI.decode("b85d0bd200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001" |> Base.decode16!(case: :lower))
[<<1::160>>, true]
"""
def decode(function_signature, data, data_type \\ :input)
def decode(function_signature, data, data_type) when is_binary(function_signature) do
function_signature
|> Parser.parse!()
|> decode(data, data_type)
end
def decode(%FunctionSelector{} = function_selector, data, data_type) do
TypeDecoder.decode(data, function_selector, data_type)
end
@doc """
Finds and decodes the correct function from a list of `ABI.FunctionSelector`s
The function is found based on the `method_id`, which is generated from the
keccak hash of the function head. More information can be found here:
https://solidity.readthedocs.io/en/develop/abi-spec.html
Keep in mind, you must include the method identifier in the passed in data
otherwise this won't work as expected. If you are decoding transaction input data
the identifier is the first four bytes and should already be there.
To find and decode events instead of functions, see `find_and_decode_event/6`
## Examples
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
...> |> ABI.find_and_decode("b85d0bd200000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001" |> Base.decode16!(case: :lower))
{%ABI.FunctionSelector{type: :function, function: "bark", input_names: ["at", "loudly"], method_id: <<184, 93, 11, 210>>, returns: [], types: [:address, :bool], state_mutability: :non_payable}, [<<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1>>, true]}
"""
def find_and_decode(function_selectors, data, data_type \\ :input) do
with {:ok, method_id, _rest} <- Util.split_method_id(data),
{:ok, selector} when not is_nil(selector) <-
Util.find_selector_by_method_id(function_selectors, method_id) do
{selector, decode(selector, data, data_type)}
end
end
@doc """
Parses the given ABI specification document into an array of `ABI.FunctionSelector`s.
Non-function entries (e.g. constructors) in the ABI specification are skipped. Fallback function entries are accepted.
This function can be used in combination with a JSON parser, e.g. [`Jason`](https://hex.pm/packages/Jason), to parse ABI specification JSON files.
Opts:
* `:include_events?` - Include events in the output list (as `%FunctionSelector{}` with a type of `:event`). Defaults to `false`
for backwards compatibility reasons.
## Examples
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification
[%ABI.FunctionSelector{type: :function, function: "bark", input_names: ["at", "loudly"], method_id: <<184, 93, 11, 210>>, returns: [], types: [:address, :bool], state_mutability: :non_payable},
%ABI.FunctionSelector{type: :function, function: "rollover", method_id: <<176, 86, 180, 154>>, returns: [:bool], types: [], state_mutability: :non_payable}]
iex> [%{
...> "constant" => true,
...> "inputs" => [
...> %{"name" => "at", "type" => "address"},
...> %{"name" => "loudly", "type" => "bool"}
...> ],
...> "name" => "bark",
...> "outputs" => [],
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "function"
...> }]
...> |> ABI.parse_specification
[%ABI.FunctionSelector{type: :function, function: "bark", method_id: <<184, 93, 11, 210>>, input_names: ["at", "loudly"], returns: [], types: [:address, :bool], state_mutability: :non_payable}]
iex> [%{
...> "inputs" => [
...> %{"name" => "_numProposals", "type" => "uint8"}
...> ],
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "constructor"
...> }]
...> |> ABI.parse_specification
[%ABI.FunctionSelector{function: nil, input_names: ["_numProposals"], inputs_indexed: nil, method_id: <<99, 53, 230, 34>>, returns: [], type: :constructor, types: [uint: 8]}]
iex> [%{
...> "payable" => false,
...> "stateMutability" => "nonpayable",
...> "type" => "fallback"
...> }]
...> |> ABI.parse_specification
[%ABI.FunctionSelector{type: :function, function: nil, returns: [], types: [], method_id: nil}]
iex> File.read!("priv/dog.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification(include_events?: true)
...> |> Enum.filter(&(&1.type == :event))
[%ABI.FunctionSelector{type: :event, function: "WantsPets", input_names: ["_from_human", "_number", "_belly"], inputs_indexed: [true, false, true], method_id: <<235, 155, 60, 76>>, types: [:string, {:uint, 256}, :bool]}]
iex> File.read!("priv/example1.abi.json")
...> |> Jason.decode!
...> |> ABI.parse_specification(include_events?: true)
"""
def parse_specification(doc, opts \\ []) do
if opts[:include_events?] do
doc
|> Enum.map(&FunctionSelector.parse_specification_item/1)
|> Enum.reject(&is_nil/1)
else
doc
|> Enum.map(&FunctionSelector.parse_specification_item/1)
|> Enum.reject(fn item -> is_nil(item) || item.type == :event end)
end
end
end
