Block Download Mini Protocol

[coot]

net_impl_protocol_block_download
Implement the mini-protocol for block body download (in sim)

This is the application level protocol for fetching ranges of blocks from another peer.

Ultimately this is a relatively simple protocol, however the final design of this protocol must be informed by the block fetching logic. See #66. Its expression relies on the framework for expressing mini-protocols. See #61.

The completion criteria for this work package is that:

• it has an interface that is deemed satisfactory for use by the block fetch logic. This relies on PoC work on the block fetch logic.
• tests in simulation that it can correctly fetch ranges of a chain, and correctly reports failure on ranges not in the current chain
• tests in simulation that multiple requests can be outstanding at once

Testing the mini protocol in isolation should cover multiple integration levels.

This epic is split into 3 tasks:

• Block Download Protocol #123 - block download protocol together with integration tests:

• direct,
• via typed Peer with connect

• Block Download: codec #124 - codec for block download protocol messages, including coherence tests for that codec
• Block Download: round trip tests which are using a codec #125 - add more integration tests:

• codec in simulation
• via local pipe

[coot]

#50 - streaming in sim
#31 - typed streaming (no latency hiding)
#52 - typed request / response protocol

[coot]

PR #319 - block fetch mini protocol using typed-protocols