* Fix tower/blockstore unsync due to external causes
* Add and clean up long comments
* Clean up test
* Comment about warped_slot_history
* Run test_future_tower with master-only/master-slave
* Update comments about false leader condition
https://hackerone.com/reports/991106
> It’s possible to use UDP gossip protocol to amplify DDoS attacks. An attacker
> can spoof IP address in UDP packet when sending PullRequest to the node.
> There's no any validation if provided source IP address is not spoofed and
> the node can send much larger PullResponse to victim's IP. As I checked,
> PullRequest is about 290 bytes, while PullResponse is about 10 kB. It means
> that amplification is about 34x. This way an attacker can easily perform DDoS
> attack both on Solana node and third-party server.
>
> To prevent it, need for example to implement ping-pong mechanism similar as
> in Ethereum: Before accepting requests from remote client needs to validate
> his IP. Local node sends Ping packet to the remote node and it needs to reply
> with Pong packet that contains hash of matching Ping packet. Content of Ping
> packet is unpredictable. If hash from Pong packet matches, local node can
> remember IP where Ping packet was sent as correct and allow further
> communication.
>
> More info:
> https://github.com/ethereum/devp2p/blob/master/discv4.md#endpoint-proof
> https://github.com/ethereum/devp2p/blob/master/discv4.md#wire-protocol
The commit adds a PingCache, which maintains records of remote nodes
which have returned a valid response to a ping message, and on-the-fly
ping messages pending a pong response from the remote node.
When handling pull-requests, those from addresses which have not passed
the ping-pong check are filtered out, and additionally ping packets are
added for addresses which need to be (re)verified.
mark_pull_request_creation time requires an exclusive lock on gossip:
https://github.com/solana-labs/solana/blob/16944e218/core/src/cluster_info.rs#L1547-L1548
Current code is redundantly marking each peer once for each request.
There are at most only 2 unique peers, whereas there are hundreds of
requests per each. So the lock is acquired hundreds of time longer than
necessary.
ClusterInfo::process_packets handles incoming packets in a thread_pool:
https://github.com/solana-labs/solana/blob/87311cce7/core/src/cluster_info.rs#L2118-L2134
However, profiling runtime shows that threads are not well utilized and
a lot of the processing is done sequentially.
This commit redistributes the work done in parallel. Testing on a gce
cluster shows 20%+ improvement in processing gossip packets with much
smaller variations.
* Follow up to persistent tower
* Ignore for now...
* Hard-code validator identities for easy reasoning
* Add a test for opt. conf violation without tower
* Fix compile with rust < 1.47
* Remove unused method
* More move of assert tweak to the asser pr
* Add comments
* Clean up
* Clean the test addressing various review comments
* Clean up a bit
* introduce store program logs in blockstore / bigtable
* fix test, transaction logs created for successful transactions
* fix test for legacy bincode implementation around log_messages
* only api nodes should record logs
* truncate transaction logs to 100KB
* refactor log truncate for improved coverage
