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https://github.com/kigawas/web3-input-decoder

A simple offline web3 transaction input decoder for functions and constructors.
https://github.com/kigawas/web3-input-decoder

ethereum web3

Last synced: about 2 hours ago
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A simple offline web3 transaction input decoder for functions and constructors.

Host: GitHub
URL: https://github.com/kigawas/web3-input-decoder
Owner: kigawas
License: mit
Created: 2021-03-25T09:18:28.000Z (over 3 years ago)
Default Branch: master
Last Pushed: 2024-11-01T16:36:57.000Z (15 days ago)
Last Synced: 2024-11-09T18:48:33.450Z (7 days ago)
Topics: ethereum, web3
Language: Python
Homepage:
Size: 480 KB
Stars: 51
Watchers: 2
Forks: 11
Open Issues: 10
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

README

        # web3-input-decoder

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A simple offline web3 transaction input decoder for functions and constructors.

## Install

```bash

pip install web3-input-decoder

```

## Quick start

Let's take a [USDT transfer transaction](https://etherscan.io/tx/0x0331fdfa070ee26b1fc7b01b246ef5e58593cbe9f4a02f7f09bf4a2aa640cf35) and the [USDT contract creator transaction](https://etherscan.io/address/0xdac17f958d2ee523a2206206994597c13d831ec7#code) as an example:

```python

>>> import json

>>> import urllib.request

>>> from web3_input_decoder import decode_constructor, decode_function

>>> f = urllib.request.urlopen("https://api.etherscan.io/api?module=contract&action=getabi&address=0xdac17f958d2ee523a2206206994597c13d831ec7")

>>> TETHER_ABI = json.loads(json.load(f)["result"])

>>> decode_function(

        TETHER_ABI, "0xa9059cbb000000000000000000000000f050227be1a7ce587aa83d5013f900dbc3be0611000000000000000000000000000000000000000000000000000000000ecdd350",

    )

[('address', '_to', '0xf050227be1a7ce587aa83d5013f900dbc3be0611'),

 ('uint256', '_value', 248370000)]

>>> decode_constructor(

        TETHER_ABI, "000000000000000000000000000000000000000000000000000000174876e800000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000c00000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000000a546574686572205553440000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000045553445400000000000000000000000000000000000000000000000000000000"

    )

[('uint256', '_initialSupply', 100000000000),

 ('string', '_name', 'Tether USD'),

 ('string', '_symbol', 'USDT'),

 ('uint256', '_decimals', 6)]

```

You can also play with it [here](https://replit.com/@kigawas/Web3-input-decoder-quick-start).

### Performance enhancement

If you have lots of inputs in the same contract to decode, consider using [`InputDecoder`](web3_input_decoder/decoder.py#L26).

```python

>>> from web3_input_decoder import InputDecoder

>>> decoder = InputDecoder(TETHER_ABI)

>>> for _ in range(10000):

>>>    decoder.decode_function(

          (

            "0xa9059cbb000000000000000000000000f050227be1a7ce587aa83d5013f900dbc3b"

            "e0611000000000000000000000000000000000000000000000000000000000ecdd350"

          ),

        )

```

## API

- [`decode_constructor`](web3_input_decoder/__init__.py#L12)

  ```python

  def decode_constructor(

      abi: List[dict],

      tx_input: Union[str, bytes],

      bytecode: Optional[Union[str, bytes]] = None,

  ) -> List[Tuple[str, str, Any]]

  ```

  **Parameters**:

  - `abi`: Contract ABI

  - `tx_input`: Transaction input to decode, with or without deployed contract bytecode

  - `bytecode`: Optional deployed contract bytecode. If this is set, `tx_input` should include bytecode

  **Returns**:

  - `List[Tuple[str, str, Any]]`: Decoded type-name-value tuples

- [`decode_function`](web3_input_decoder/__init__.py#L37)

  ```python

  def decode_function(

      abi: List[dict], tx_input: Union[str, bytes]

  ) -> List[Tuple[str, str, Any]]

  ```

  **Parameters**:

  - `abi`: Contract ABI

  - `tx_input`: Transaction input to decode

  **Returns**:

  - `List[Tuple[str, str, Any]]`: Decoded type-name-value tuples

## Rationale

Existing solutions are not satisfying to me, e.g.:

1. [web3py](https://web3py.readthedocs.io/en/latest/web3.contract.html#web3.contract.Contract.decode_function_input) can only decode function calls and it's necessary to be online to set up a provider first.

2. [ethereum-input-decoder](https://github.com/tintinweb/ethereum-input-decoder) is not maintained and it contains several glitches.