This modifies the connection manager to provide support for accepting
inbound connections on a caller-provided set of listeners and notify the
caller via a callback.
This is only the minimum work necessary to get inbound support into the
connection manager. The intention for future commits is to move more
connection-related logic such as limiting the maximum number of overall
connections and banned peer tracking into the connection manager.
This removes the type definitions for the callback functions in favor of
declaring them directly in the Config struct. This is more consistent
with the rest of the code base and is preferred since it means callers
reviewing the documentation don't have to follow another level of
indirection to figure out the signature.
This commit introduces package connmgr which contains connection
management related functionality.
The following is an overview of the features the package provides:
- Maintain fixed number of outbound connections
- Optional connect-only mode
- Retry persistent connections with increasing back-off
- Source peers from DNS seeds
- Use Tor to resolve DNS
- Dynamic ban scores
- Test coverage
In addition, btcd has been refactored to make use of the new package by
extending the connection manager to work with the server to source and
maintain peer connections. The following is a broad overview of the
changes to integrate the package:
- Simplify peer state by removing pending, retry peers
- Refactor to remove retries which are now handled by connmgr
- Use callback to add addresses sourced from the DNS seed
Finally the following connection-related things have been improved as a
part of this refactor:
- Fixes 100% cpu usage when network is down (#129)
- Fixes issues with max peers (#577)
- Simplify outbound peer connections management
