feat: ban a peer if its last state isn't changed after timeout

[yangby-cryptape]

Description

If a peer sent the same state to light client again and again, light client should ban it.

Just let the light client don't update the update timestamp for cached last-state if it isn't changed, and ban the peer when do timeout checks.

ckb-light-client/src/protocols/light_client/mod.rs

Lines 502 to 507 in 86865db

	for peer_index in self.peers().get_peers_which_have_timeout(now) {
	self.peers().mark_fetching_headers_timeout(peer_index);
	self.peers().mark_fetching_txs_timeout(peer_index);
	warn!("peer {}: reach timeout", peer_index);
	if let Err(err) = nc.disconnect(peer_index, "reach timeout") {

ckb-light-client/src/protocols/mod.rs

Lines 25 to 26 in 86865db

	// Ban a peer if it reach any timeout.
	pub const MESSAGE_TIMEOUT: u64 = 60 * 1000;

Commits:

• test: test the cached state when received same last state from a peer more than once
• feat: keep the update timestamp if the last state is as the same as the previous
• feat: ban a peer if its last state isn't changed after timeout

[codecov-commenter]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (86865db) 71.39% compared to head (b553660) 71.37%.

Files	Patch %	Lines
src/protocols/light_client/peers.rs	42.85%	8 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #170      +/-   ##
===========================================
- Coverage    71.39%   71.37%   -0.03%     
===========================================
  Files           25       25              
  Lines         6479     6498      +19     
===========================================
+ Hits          4626     4638      +12     
- Misses        1853     1860       +7     

Flag	Coverage Δ
unittests	71.37% <75.75%> (-0.03%)	⬇️

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