An example of where this might be useful is allowing a node to connect blocksonly during IBD but then becoming a full-node once caught up with the latest block. This might also even want to be the default behaviour since during IBD most TXs appear to be orphans, and are routinely dropped (for example when a node disconnects). Therefore, this can waste a lot of bandwidth.
Additionally, another pull could be written to stop relaying of TXs to nodes that are clearly far behind the latest block and are running a node that doesn't store many orphan TXs, such as recent versions of Bitcoin Core.
Previously peers which implement a protocol version less than NO_BLOOM_VERSION
would not be disconnected for sending a filter command, regardless of the
peerbloomfilter option.
Many node operators do not wish to provide expensive bloom filtering for SPV
clients, previously they had to cherry pick the commit which enabled the
disconnect logic.
The default should remain false until a sufficient percent of SPV clients
have updated.
Lets nodes advertise that they offer bloom filter support explicitly.
The protocol version bump allows SPV nodes to assume that NODE_BLOOM is
set if NODE_NETWORK is set for pre-170004 nodes.
Also adds an option to turn bloom filter support off for nodes which
advertise a version number >= 170004. Nodes attempting to use bloom
filters on such protocol versions are banned, and a later upgade
should drop nodes of an older version which attempt to use bloom
filters.
Much code stolen from Peter Todd.
Zcash: Implements Zcash equivalent of BIP 111; deploys with Overwinter
