Decoding function inputs for an Ethereum call failed

[ziegfried]

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

Subgraph fails with error when attempting to decode some invalid inputs for an Ethereum function call.

Subgraph instance failed to run: Failed to process trigger: Generating function inputs for an Ethereum call failed = Cannot decode bytes16, code: SubgraphSyncingFailure, id: QmcVgWVzeugoZjAdJHbKxD9Gt1FCB4cq2JzknoNKPdw9zN, updates: 0

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

1. Clone https://github.com/ziegfried/peepeth-subgraph
2. Edit subgraph.yaml: Remove line-comment from changeName(bytes16) handler

        # - function: changeName(bytes16)
        #   handler: handleChangeName

3. Deploy

What is the expected behavior?

Graph node should ignore the invalid function call and keep processing the subgraph.

[Jannis]

I've managed to reproduce this locally:

   block_number: 6774386
    block_hash: 0x7fe3891b67aea2e048d02d764b83019b21df764a391617d73fcaf88a43db06be
     May 15 16:51:55.304 INFO 1 trigger found in this block for this subgraph
     May 15 16:51:55.305 DEBG Start processing Ethereum call, to: 0xfa28…ce1d, data_source: Contract, handler: handleChangeName, function: changeName(bytes16)
     May 15 16:51:55.589 INFO Done processing Ethereum call, ms: 284, handler: handleChangeName, function: changeName(bytes16)
   component: BlockStream
    May 15 16:51:55.753 DEBG Requesting traces for block 6774518
    May 15 16:51:56.024 DEBG Received 261 traces for block 6774518
    May 15 16:51:56.025 DEBG Skipping 131 irrelevant block(s)
   block_number: 6774518
    block_hash: 0x58dd82c8082b627440289b1cbeb9fbe7c97269ddcffdcf3836487da0f18f9328
     May 15 16:51:56.033 INFO 1 trigger found in this block for this subgraph
   component: BlockStream
    May 15 16:51:56.035 DEBG Terminating chain head updates; channel closed
   May 15 16:51:56.036 ERRO Subgraph instance failed to run: Failed to process trigger: Generating function inputs for an Ethereum call failed = Cannot decode bytes16, code: SubgraphSyncingFailure, id: QmcBMXknjNmo2bZ3G3bqMYFkpZEcjUjV96CocMDnHxdKby

[Jannis]

Transaction: https://etherscan.io/tx/0x837a8753e9b9d1a57a055b49b95ddbff85bdb1f099951e4289848bd490ddb171

Input data:

Etherscan:  0x5047b3376c65616465727300000000000000000000000000000000000000000000000000
Graph Node: 0x5047b337737475617274

So somehow our input data is different and invalid. The first four bytes of the input data are for the function signature itself. These are identical in both cases.

If we strip those off, we get:

Etherscan:  6c65616465727300000000000000000000000000000000000000000000000000
Graph Node: 737475617274

The problem here is that the tx has an input of 0x5047b337737475617274. The function signature expects a bytes16, but after stripping off the first 4 bytes for the method id the function parameters data is only of length 6.

The serialization library we use, ethabi, does not successfully deserialize the input because it is expecting 16 bytes. Solidity could be accepting the 6 byte input (and maybe padding it in the runtime) to populate a bytes16 for processing.

I'm modifying ethabi to handle this.

[Jannis]

This is worked on in graphprotocol/ethabi#8.

[azf20]

@Jannis & @fordN do you know if this is still a live issue? The Linked ethabi PR was closed

[leoyvens]

Closing because this is old and seems fixed