P2P: Add additional info to handshake message

[heifner]

The os field of handshake currently contains one of osx, linux, win32, other.

Repurpose this field to include additional information about the peer.
|vt={time_point in seconds} - last vote received time
|ts={trx_in_progress_size kilo-bytes} - can be zero if no speculative trx currently queued for execution
|tt={time_point in seconds} - last trx received time

[bhazzard]

@heifner Can you consider how we would want to do this if breaking changes are on the table anyway as a v2.0.0 item or as a network protocol change in v1.1.0?

[heifner]

Current net_plugin protocol version: proto_savanna = 9.
Add new protocol version: proto_handshake_v2 = 10

handshake_message_v2 sent instead of handshake_message when handshake_message::network_version is >= proto_handshake_v2.

struct handshake_message_v2 : handshake_message {
   block_num_type head_num = 0;
   block_id_type head_id;
   block_timestamp_type head_block_time;
   block_timestamp_type fork_head_block_time;
   fc::time_point last_vote_received;
   fc::time_point last_trx_received;
   fc::time_point last_blk_received;
   size_t trx_in_progress_size_bytes = 0;
   bool block_log = true;
   block_num_type start_block = 0;
   block_num_type end_block = 0;
};

• On first handshake_message received when network_verison > proto_handshake_v2 send back a handshake_message_v2.
• Do not attempt sync from peer when block_log == false or needed block is < start_block.
• Add handshake_message_v2 info to connection status response.
• If configured as a block producer or finalizer, generate error log message if all peers do not have a last_vote_received and Savanna is active.

[bhazzard]

@heifner can you add information on how each of these fields would be useful?

[heifner]

Replaced by #1083