ServiceProviderRegistry: align on canonical decoding `address` from `bytes`

[wjmelements]

We already align on encoding (always use 20 bytes).

Decoding address is simple when the length is 20 bytes but we have different behavior in different places when the length is different.

Curio currently uses the bottom 20 bytes and might fail when the address is shorter than that. I think our canonical decoding behavior should match the behavior of address(uint160(BigEndian.decode(values[i]))) in Solidity.
Can reuse these synapse test cases from packages/synapse-core/src/test/capabilities.test.ts.

These fields are fairly unimportant so far so this is not urgent.

[siddharthbaleja7]

@rjan90 can you assign this issue to me

[siddharthbaleja7]

Hi @wjmelements,

I've been investigating this issue and wanted to share my findings to make sure I'm on the right track.

The issue mentions that:

"Curio currently uses the bottom 20 bytes and might fail when the address is shorter than that."

I searched through the Curio (Go) project for this logic, focusing on code related to the ServiceProviderRegistry.

In pdp/contract/utils.go, I found the FSRegister function, which processes event logs. This code already seems to be using the correct canonical decoding:

// Compare that event log contains the correct payee
payee := common.BytesToAddress(vLog.Topics[1].Bytes())

The Go Ethereum common.BytesToAddress() function already handles padding for short inputs and truncating long ones — which matches the desired Solidity behavior.

I also noticed the issue references a synapse-sdk (TypeScript) test file. I found a merged pull request in the synapse-sdk project (FilOzone/synapse-sdk#364) that seems to fix this exact bug (the .slice(-20) logic) in the TypeScript codebase.

Based on this, it looks like the bug was in synapse-sdk (and is now fixed there), while the Curio (Go) project is already using the correct decoding.

Am I understanding this correctly, or is there a different Go file in the Curio project where this “bottom 20 bytes” logic exists?

Thanks for the help!

[wjmelements]

// Compare that event log contains the correct payee
payee := common.BytesToAddress(vLog.Topics[1].Bytes())

This task is not about event decoding. It is about decoding product capabilities. You should be fixing and testing the function capabilitiesToOffering.

truncating long ones — which matches the desired Solidity behavior.

That is not the solidity behavior of BigEndian.decode. There is another case, where the size is larger than 32 bytes.

[siddharthbaleja7]

@wjmelements Can you review this pr.