This commit implements stall detection logic at the peer level to detect
and disconnect peers that are either not following the protocol in
regards to expected response messages or have otherwise stalled. This
is accomplished by setting deadlines for each message type which expects
a response and periodically checking them while properly taking into
account processing time.
There are an increasing number of nodes on the network which claim to be
full nodes, but don't actually properly implement the entire p2p
protocol even though they implement it enough to cause properly
implemented nodes to make data requests to which they never respond.
Since btcd currently only syncs new blocks via single sync peer and,
prior to this commit only had very basic stall detection, this could
lead to a situation where the block download became stalled indefinitely
due to one of these misbehaving peers. This commit fixes that issue
since the stalled peer will now be detected and disconnected which leads
to a new sync peer being selected.
This logic will also fit nicely with the future multi-peer sync model
which is on the roadmap and for which infrastructure work is underway.
Fixes#486 and fixes#229.
This commit modifies the ping logic in the peer to ping on an interval
regardless of what other messages are being sent versus the previous
method of delaying the ping each time a message that is expected to
receive data is sent.
This helps improve the ping statistics and simplifies its logic.
This fleshes out the doc.go documentation which is shown on godoc, the
README.md shown on github, and improves a couple of comments for the
fields in the Config struct.
This commit introduces package peer which contains peer related features
refactored from peer.go.
The following is an overview of the features the package provides:
- Provides a basic concurrent safe bitcoin peer for handling bitcoin
communications via the peer-to-peer protocol
- Full duplex reading and writing of bitcoin protocol messages
- Automatic handling of the initial handshake process including protocol
version negotiation
- Automatic periodic keep-alive pinging and pong responses
- Asynchronous message queueing of outbound messages with optional
channel for notification when the message is actually sent
- Inventory message batching and send trickling with known inventory
detection and avoidance
- Ability to wait for shutdown/disconnect
- Flexible peer configuration
- Caller is responsible for creating outgoing connections and listening
for incoming connections so they have flexibility to establish
connections as they see fit (proxies, etc.)
- User agent name and version
- Bitcoin network
- Service support signalling (full nodes, bloom filters, etc.)
- Maximum supported protocol version
- Ability to register callbacks for handling bitcoin protocol messages
- Proper handling of bloom filter related commands when the caller does
not specify the related flag to signal support
- Disconnects the peer when the protocol version is high enough
- Does not invoke the related callbacks for older protocol versions
- Snapshottable peer statistics such as the total number of bytes read
and written, the remote address, user agent, and negotiated protocol
version
- Helper functions for pushing addresses, getblocks, getheaders, and
reject messages
- These could all be sent manually via the standard message output
function, but the helpers provide additional nice functionality such
as duplicate filtering and address randomization
- Full documentation with example usage
- Test coverage
In addition to the addition of the new package, btcd has been refactored
to make use of the new package by extending the basic peer it provides to
work with the blockmanager and server to act as a full node. The
following is a broad overview of the changes to integrate the package:
- The server is responsible for all connection management including
persistent peers and banning
- Callbacks for all messages that are required to implement a full node
are registered
- Logic necessary to serve data and behave as a full node is now in the
callback registered with the peer
Finally, the following peer-related things have been improved as a part
of this refactor:
- Don't log or send reject message due to peer disconnects
- Remove trace logs that aren't particularly helpful
- Finish an old TODO to switch the queue WaitGroup over to a channel
- Improve various comments and fix some code consistency cases
- Improve a few logging bits
- Implement a most-recently-used nonce tracking for detecting self
connections and generate a unique nonce for each peer
