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.
This behavior seems to have been quite racy and broken.
Move nLocalHostNonce into CNode, and check received nonces against all
non-fully-connected nodes. If there's a match, assume we've connected
to ourself.
waitfornewblock waits until a new block is received, or the timeout expires, then
returns the current block height/hash.
waitforblock waits for a specific blockhash, or until the timeout expires, then
returns the current block height/hash. If the target blockhash is the current
tip, it will return immediately.
waitforblockheight waits until the tip has reached a certain height or higher,
then returns the current height and hash.
waitforblockheight is used to avoid polling in the rpc tests.
Wladimir J. van der Laan