Support sending and receiving multiple Justifications

[octol]

Follow up to #7640 , where we add support for also sending multiple Justifications across the network. We include in the request if we support receiving multiple at once, and are backwards compatible with old nodes.

Resolves #8172

[andresilva]

Overall the changes LGTM but I'd like to make sure this is adequately tested to avoid any breakage.

[andresilva]

What's the difference between #7556 and #8172? Isn't #8172 a subset of #7556?

[octol]

What's the difference between #7556 and #8172? Isn't #8172 a subset of #7556?

#8172 was supposed to track the pieces specific to the networking and also the remaining work needed. It's the one that the code refers to in client/network when the adding the GRANDPA consensus engine ID tag

[octol]

Overall the changes LGTM but I'd like to make sure this is adequately tested to avoid any breakage.

Making a push to properly test this so we can hopefully merge it soon

[tomaka]

Looks good

[andresilva]

@octol Just to be sure before I click the merge button: when you tested this locally you tested both scenarios right? I.e. new nodes serving old nodes, and old nodes serving new nodes.

[octol]

@octol Just to be sure before I click the merge button: when you tested this locally you tested both scenarios right? I.e. new nodes serving old nodes, and old nodes serving new nodes.

I tested having two nodes built using this PR finalizing blocks, and then a third and fourth node connecting with --no-grandpa, one based on master and one on this PR, confirming that they are both able to follow finality (at sync and when the set id changes).

And then I redid this with the same setup but the nodes finalizing blocks were built using master.

This should cover both scenarios I think

[andresilva]

@octol Thanks!

[andresilva]

bot merge

[ghost]

Trying merge.