eth: Add sidecars validation to sender and recipient

[ngotchac]

Some "sidecars" validation steps were missing in a few places still: the downloader when validating a Header, and the handler when delivering Blocks.

[buddh0]

if distance between the target block and the latest block is larger than MinBlocksForBlobRequests,
then the blob data is not need, either download form others or deliver to others.

[buddh0]

when download from others
the check logic is in func IsDataAvailable

[ngotchac]

If the distance between the target block and the latest block is larger than MinBlocksForBlobRequests, then the blob data is not needed

I wasn't aware of that, thanks! I updated the PR so that it takes it into account. The reasoning here is just to make the same check for Sidecars() availability as we do for the block body in:

body := chain.GetBody(hash)
if body == nil {
    continue
}

and if we're missing a required Sidecars() for don't want for other peers to mark us as invalid ; it's better to just not respond to this request's block.

When downloading from others, the check logic is in func IsDataAvailable()

The issue is that currently, the IsDataAvailable() check when receiving blocks is only in func (bc *BlockChain) insertChain(...) (int, error) which returns an error when the Sidecars() part isn't valid, which eventually bubbles up to func (d *Downloader) LegacySync and drops the peer.

Having this check in func (q *queue) DeliverBodies -> validate will enable still importing valid blocks, without droping the peer if they don't have the Sidecars() available.

[buddh0]

when do full sync,
if distance between the target block and the latest block is larger than MinBlocksForBlobRequests, then the blob data is not need
this check will reject the target block in the wrong way

[ngotchac]

Same answer as below, I think it's a good thing to not mark a peer as invalid if some sidecars are missing. I could add the check for MinBlocksForBlobRequests here though, WDYT?

[buddh0]

Same answer as below, I think it's a good thing to not mark a peer as invalid if some sidecars are missing. I could add the check for MinBlocksForBlobRequests here though, WDYT?

👌

[ngotchac]

I'm closing this PR. After thinking about it, adding the check for MinBlocksForBlobRequests in the sender might not be necessary, and adding it in (q *queue) DeliverBodies -> validate isn't feasible since the queue doesn't know what the top of the chain should be.

It seems that issues related to sidecars not being delivered have vanished, at least for now...