Erigon | trace_call guide

Erigon is becoming a more common Ethereum client, and this repo describes the trace_call method, which is available by querying a node running Erigon as a client.

This article from Chainstack goes deep into how Erigon works compared to Geth.

trace_transaction guide

trace_transaction is one of the methods available in Erigon to trace, and it takes a transaction hash as input, allowing you to see the internal functions calls made into a smart contract.

trace_transaction method— parameters accepted and returned

Parameters:

transaction hash - Hash of the transaction to trace.

Returns:

array - Block traces.

Expand to see all of the returned parameters

• action - ParityTrace Object, with the following fields:

  • traceaddress - Array.

  • calltype - String.

  • includeintrace - Boolean.

  • isprecomplied - Boolean.

  • type - String.

  • creationmethod - String.

  • from - Address.

  • to - Address.

  • gas - Quantity.

  • value - Quantity.

  • input - Data.

  • result - ParityTraceResult object with the following fields:

    • gasused - Quantity

    • output - Data

    • address - Address

    • code - Data

  • subtraces - Array.

  • author - Address.

  • rewardtype - String.

  • error - String.

• blockhash - String of the block hash.

• blocknumber - Quantity.

• result - ParityTraceResult object which has the following fields:

  • gasused - Quantity

  • output - Data

  • address - Address

  • code - Data

• subtraces - Quantity.

• traceaddress - Array.

• transactionhash - Hash.

• transactionposition - Quantity.

• type - String.

• error - String.

Code examples

cURL

curl -X POST 'ERIGON_NODE' \
-H 'Content-Type: application/json' \
--data '{"method":"trace_transaction","params":["0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f"],"id":1,"jsonrpc":"2.0"}'

web3.py

from web3 import Web3

node_url = "ERIGON_NODE_URL"

# Create the node connection
web3 = Web3.HTTPProvider(node_url)

# print trace transaction
trace = web3.make_request("trace_transaction", ["0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f"])
#print(trace) # raw result

# Parse the result in a more readable way
for action in trace['result']:
    for key, val in action.items():
        print(key +':', val)

Analyze a transaction

You will need access to an Ethereum node running Erigon, you can get one with Chainstack.

Let's analyze this transaction:

This transaction is made by an account to a smart contract.

The transaction sends this data to the smart contract (calls the claim function):

Function: claim(address _receiver, uint256 _quantity, address _currency, uint256 _pricePerToken, bytes32[] _proofs, uint256 _proofMaxQuantityPerTransaction) ***

MethodID: 0x7a5a8e7e
[0]:  0000000000000000000000000ee46e8ca7933dd131e7369ee9d871a7e430067e
[1]:  0000000000000000000000000000000000000000000000000000000000000001
[2]:  000000000000000000000000eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
[3]:  0000000000000000000000000000000000000000000000000000000000000000
[4]:  00000000000000000000000000000000000000000000000000000000000000c0
[5]:  0000000000000000000000000000000000000000000000000000000000000000
[6]:  000000000000000000000000000000000000000000000000000000000000000a
[7]:  09f950e600088b8f3c83a2a1fe308d099c818d122c8d60b7f73d962d68b83171
[8]:  3c23450053c5193e661f163aa190964e9f81eb7c419d2273b45afb22498292bc
[9]:  64aebc659f0ddecec9d2c95668d708b439cd8efb23872724a3e4d0b223463402
[10]: 44a955e75c9e4de07cd2c9eb99b144c468597b5d4bd6c42b29b7ba499915d07a
[11]: c02dec6a1ac983c5f340096f1076ec049bcfb3e8b3bc55d0dadcddf68335db7c
[12]: 88e7a619f7ea2cbb2e67d9ea3eac23f141f4d04d686bcbfa92edfabb91cf5b40
[13]: 887c08fd8316423db1fa67dcb4ec0498bcfa9df86fdf32d052ed30fa4c0b8de1
[14]: f7d0f7f5859b0dc082c8c37f32c289d48e8aabd0dcefcf1688503165e6159c07
[15]: 0cb354a05f36ef1fd4b9c334e4b5435f0007191af09640ae4c5e03c3169e9a5e
[16]: b5e2a40dc6e10ca58622afa8872e7e969a0cb03959d12b80b8d6c0471ebc2a6d

raw data:

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

Call trace_transaction :

Now calling trace_transaction (from Postman), we can analyze what happens within the smart contract:

curl -X POST 'ERIGON_NODE' \
-H 'Content-Type: application/json' \
--data-raw '{"method":"trace_transaction","params":["0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f"],"id":1,"jsonrpc":"2.0"}'

Will return 2 calls:

Expand to see the entire results retrieved

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": [
        {
            "action": {
                "from": "0x0ee46e8ca7933dd131e7369ee9d871a7e430067e",
                "callType": "call",
                "gas": "0x3e67a",
                "input": "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",
                "to": "0x7340bf9efc961d65724fcf142e9579fa29832909",
                "value": "0x0"
            },
            "blockHash": "0xb9ad714b627e0e7905c9c7a7f0b83908357f7f2dc3c8f0baca52baf437b1cec2",
            "blockNumber": 15013721,
            "result": {
                "gasUsed": "0x3ceb0",
                "output": "0x"
            },
            "subtraces": 1,
            "traceAddress": [],
            "transactionHash": "0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f",
            "transactionPosition": 193,
            "type": "call"
        },
        {
            "action": {
                "from": "0x7340bf9efc961d65724fcf142e9579fa29832909",
                "callType": "delegatecall",
                "gas": "0x3cc5f",
                "input": "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",
                "to": "0xb1bd9d7942a250ba2dce27dd601f2ed4211a60c4",
                "value": "0x0"
            },
            "blockHash": "0xb9ad714b627e0e7905c9c7a7f0b83908357f7f2dc3c8f0baca52baf437b1cec2",
            "blockNumber": 15013721,
            "result": {
                "gasUsed": "0x3c3e3",
                "output": "0x"
            },
            "subtraces": 0,
            "traceAddress": [
                0
            ],
            "transactionHash": "0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f",
            "transactionPosition": 193,
            "type": "call"
        }
    ]
}

It basically shows details like gas used, block, the call type, and so on for every action happening during the transaction.

The first one is the call from the account to the smart contract:

callType : call

"action": {
                "from": "0x0ee46e8ca7933dd131e7369ee9d871a7e430067e",
                "callType": "call",
                "gas": "0x3e67a",
                "input": "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",
                "to": "0x7340bf9efc961d65724fcf142e9579fa29832909",
                "value": "0x0"
            },
            "blockHash": "0xb9ad714b627e0e7905c9c7a7f0b83908357f7f2dc3c8f0baca52baf437b1cec2",
            "blockNumber": 15013721,
            "result": {
                "gasUsed": "0x3ceb0",
                "output": "0x"
            },
            "subtraces": 1,
            "traceAddress": [],
            "transactionHash": "0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f",
            "transactionPosition": 193,
            "type": "call"
        },

It looks like that this first action is a call from the account sending the transaction to the smart contract 0x7340bf9efc961d65724fcf142e9579fa29832909

You can see the same on Etherscan using the Parity Trace function:

Parity VM Trace

Note that the input matches the raw data sent with the transaction because that is what tells the contract what to do.

The second one is the smart contract sending a delegateCall to another smart contract:

callType : delegateCall

{
            "action": {
                "from": "0x7340bf9efc961d65724fcf142e9579fa29832909",
                "callType": "delegatecall",
                "gas": "0x3cc5f",
                "input": "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",
                "to": "0xb1bd9d7942a250ba2dce27dd601f2ed4211a60c4",
                "value": "0x0"
            },
            "blockHash": "0xb9ad714b627e0e7905c9c7a7f0b83908357f7f2dc3c8f0baca52baf437b1cec2",
            "blockNumber": 15013721,
            "result": {
                "gasUsed": "0x3c3e3",
                "output": "0x"
            },
            "subtraces": 0,
            "traceAddress": [
                0
            ],
            "transactionHash": "0x3aeaf88cf789d42533714606297bcddf3613f9092a57f2f1e9f2fb8cd0c8831f",
            "transactionPosition": 193,
            "type": "call"
        }

So it looks like it uses a proxy smart contract.

We can add Basti's article once is published!

The account sends the transaction to the "proxy" smart contract to claim an NFT, then the proxy contract sends a delegatedCall to the contract that will execute the function.

You can see the same on Etherscan using the Parity Trace function:

Parity VM Trace

Different type of calls

In this example, we can see that the two actions make two types of calls:

• call

call in this case refers to how the account interacts with the smart contract, and it is defined as a low-level interface for sending a message to a contract.

Essentially call is used by an account to send a message, in this case, code, to a smart contract telling it to execute a public or external function. Using call, the account can only call a function in the smart contract directly.

• delegatecall

A delegatecall is used in case the smart contract that receives the transaction wants to call another function from another smart contract, but using its storage, balance, and address supplied to the function.

Account ——— send transaction ———> contract A ——— calls function ———> contract B

This is a common occurrence when interacting with proxy contracts and upgradable smart contracts.

Conclusion

We just learned that claiming an NFT from this contract will send the transaction to another contract to call a function, and we would not have known this without tracing it.