CConnman then passes the current best height into CNode at creation time.
This way CConnman/CNode have no dependency on main for height, and the signals
only move in one direction.
This also helps to prevent identity leakage a tiny bit. Before this change, an
attacker could theoretically make 2 connections on different interfaces. They
would connect fully on one, and only establish the initial connection on the
other. Once they receive a new block, they would relay it to your first
connection, and immediately commence the version handshake on the second. Since
the new block height is reflected immediately, they could attempt to learn
whether the two connections were correlated.
This is, of course, incredibly unlikely to work due to the small timings
involved and receipt from other senders. But it doesn't hurt to lock-in
nBestHeight at the time of connection, rather than letting the remote choose
the time.
Tests if addresses are online or offline by briefly connecting to them. These short lived connections are referred to as feeler connections. Feeler connections are designed to increase the number of fresh online addresses in tried by selecting and connecting to addresses in new. One feeler connection is attempted on average once every two minutes.
This change was suggested as Countermeasure 4 in
Eclipse Attacks on Bitcoin’s Peer-to-Peer Network, Ethan Heilman,
Alison Kendler, Aviv Zohar, Sharon Goldberg. ePrint Archive Report
2015/263. March 2015.
Updating documentation for adding new unit test files
Removing unneeded sentence from README
Removing uint160_tests.cpp as it DNE
Formatting command line instructions to use ``
fixing 80 char formatting issue in README
fixing more nits
mininode now supports witness transactions/blocks, blocktools
has a helper for adding witness commitments to blocks, and script
has a function to calculate hashes for signature under sigversion
1, used by segwit.
Py3 conversion by Marco Falke
Test to make sure upgraded nodes don't ask for non-wit blocks by
Gregory Sanders.
Johnson Lau