shadow-reth

A single-node implementation of a Shadow RPC on top of Reth.

shadow-reth contains a series of Reth modifications that enable you to generate shadow events via Execution Extensions, and retrieve them easily with a custom RPC Extension.

See our blog post for more information.

Getting Started

You can get started with running shadow-reth in four steps:

Clone this repository
Generate a shadow node configuration using any external tool
Build and install the shadow-reth binary
Fetch shadow events via the shadow_getLogs JSON-RPC endpoint

Step 1: Clone this repository

git clone https://github.com/shadow-hq/shadow-reth
cd shadow-reth

Step 2: Configure your shadow node

To quickly get started, you can use the example shadow.json file in this repository. It contains recompiled bytecode for the WETH contract with an added ShadowTransfer event.

cp shadow.json.example shadow.json

Otherwise, see the Shadow Configuration section below for detailed instructions on how to configure your shadow node.

Step 3: Build and install `shadow-reth`

cargo install --locked --path bin/shadow-reth --bin shadow-reth

# start your shadow-reth node
shadow-reth node [RETH OPTIONS]

Step 4: Fetch shadow events via `shadow_getLogs`

curl http://127.0.0.1:8545 \
-X POST \
-H "Content-Type: application/json" \
--data '{"method":"shadow_getLogs","params":[{"address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"}],"id":1,"jsonrpc":"2.0"}' \
| json_pp

Shadow Configuration

With Shadow

Navigate to https://app.shadow.xyz
Search for the contract you wish to modify using the search bar at the top of the webpage.

View Screenshot
Open the contract in the editor and make your changes. When you’re satisfied with your shadow contract, use the compile button, and then the deploy button.

View Screenshots
On the home screen, click on the “Reth ExEx” tab, then click “Download JSON”.

View Screenshots

With Foundry

Clone the contract source from a verified contract on Etherscan.

forge clone 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

Modify the cloned source code
Compile your modified contract, and copy the deployed bytecode from the compiler output:

# compile your changes
forge build

# get the deployed bytecode
CONTRACT_SRC_FILE=Contract.sol
CONTRACT_NAME=WETH9
grep '"deployedBytecode":' out/$CONTRACT_SRC_FILE/$CONTRACT_NAME.json | sed -n 's/.*"object": *"\([^"]*\)".*/\1/p'

Add the contract address and shadow bytecode to shadow.json:

{
  "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2": "0x60606040..."
}

How does it work?

Here's how it works at a high level:

Generate shadow bytecode using any external tool, such as foundry. This bytecode is then added to shadow.json, which simply maps contract addresses to their shadow bytecode.

For example, if you wanted to shadow Wrapped Ether, you would add the following to shadow.json:
```
{
  "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2": "0x60606040..."
}
```
Run shadow-reth, exactly like you would start and run a normal Reth node. When a block is committed to the chain, an ExExNotification is emitted and handled by ShadowExEx, which re-executes each transaction in the block, using a ShadowDatabase (which implements revm::Database), with the shadow bytecode injected as defined in shadow.json. In addition to this, the base_fee_per_gas is set to 0, allowing shadow contracts to perform arbitrary computations without worrying about gas costs. Events emitted by shadow contracts are then stored in a sqlite database in revm's datadir.

Note: All log index fields (block_log_index, transaction_log_index) will include shadow events. As a result, shadow events will be interleaved with canonical events in the same block, and log indices will not match the canonical chain.

A namespaced shadow JSON-RPC (see ShadowRpc) is exposed, which allows you to interact with your shadowed contracts. Currently, only shadow_getLogs is implemented, which allows you to retrieve Shadow Events emitted by your shadow contracts.

Note: for this example, we've added a simple ShadowTransfer(address,address,uint256) event to the Wrapped Ether shadow bytecode. This event has the signature 0xe7742d659c2c3c18fba9c357096ed6d568223cb89064e8bc947b709cba2a6ab7.

curl http://127.0.0.1:8545 \
-X POST \
-H "Content-Type: application/json" \
--data '{"method":"shadow_getLogs","params":[{"address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"}],"id":1,"jsonrpc":"2.0"}' \
| json_pp

Expand response

{
    "jsonrpc": "2.0",
    "result": [
        {
            "address" : "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
            "blockHash" : "0xe54e22affd13be3e77449a5af5c29d2aee11ffb4f3da44845544f4d55de24e8c",
            "blockNumber" : "00000000012fd986",
            "data" : "0x000000000000000000000000000000000000000000000000052a871b93874afb",
            "logIndex" : "1",
            "removed" : false,
            "topics" : [
                "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
                "0x000000000000000000000000961ec3bb28c9e98a040c4bded38917aa96b791be",
                "0x0000000000000000000000003fc91a3afd70395cd496c647d5a6cc9d4b2b7fad",
                null
            ],
            "transactionHash" : "0xa92037f3e25559e6ccdfdd8695286be525eb7d36f194176a4d577e6ef4409545",
            "transactionIndex" : "123"
        },
        {
            "address" : "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
            "blockHash" : "0xe54e22affd13be3e77449a5af5c29d2aee11ffb4f3da44845544f4d55de24e8c",
            "blockNumber" : "00000000012fd986",
            "data" : "0x000000000000000000000000000000000000000000000000052a871b93874afb",
            "logIndex" : "2",
            "removed" : false,
            "topics" : [
                "0xe7742d659c2c3c18fba9c357096ed6d568223cb89064e8bc947b709cba2a6ab7",
                "0x000000000000000000000000961ec3bb28c9e98a040c4bded38917aa96b791be",
                "0x0000000000000000000000003fc91a3afd70395cd496c647d5a6cc9d4b2b7fad",
                null
            ],
            "transactionHash" : "0xa92037f3e25559e6ccdfdd8695286be525eb7d36f194176a4d577e6ef4409545",
            "transactionIndex" : "123"
        },
        ...
    ]
}

As a result, shadow-reth allows you to run a trustless, fully open-source version of a shadow node.

Limitations

Gas limits: shadow-reth does not override gas limits when re-executing a block with ShadowExecutor for data consistency reasons. Transactions may fail if they run out of gas during shadow re-execution, and no shadow events will be emitted for that transaction.
Backfilling: shadow-reth does not backfill shadow events. If you start running shadow-reth on a synced Reth node, shadow-reth will only generate shadow events for blocks that have been processed since shadow-reth was started. If you want historical shadow events, you’ll need to re-sync your Reth node from genesis. We’re working closely with the Reth team to improve this.
Decoding: shadow-reth is designed to be analogous to a regular node, which doesn’t include event decoding. If you want to decode shadow events, we recommend polling the shadow_getLogs endpoint in a separate process.
Websockets: Shadow events will not be published over eth_subscribe websocket subscriptions.

Getting Help

If you have any questions, first see if the answer to your question can be found in the reth book

If the answer is not there and is specific to shadow-reth, you can:

Join the Telegram to get help, or
Open an issue with the bug

Contributing

See our contributing guidelines.

Security

This code has not been audited, and should not be used in any production systems.

Acknowledgements

shadow-reth wouldn't be possible without the hard work of the following projects:

Reth: The foundation of shadow-reth, an Ethereum full node implementation that is focused on being user-friendly, highly modular, as well as being fast and efficient.
Revm: Revm is an EVM written in Rust that is focused on speed and simplicity. Revm is the backbone of shadow-reth’s ShadowExecutor, as well as Reth itself.

abdelhaqs/shadow-reth