Sapling merkle tree implementation
Closes#3056.
Please also review https://github.com/zcash/librustzcash/pull/8
This PR:
1. Introduces ZCSaplingIncrementalMerkleTree using Pedersen hashes.
2. Adds support for Sapling anchors into consensus rules. (Adds commitments, checks anchors are correct, handles block (dis)connects, etc.)
3. Handles mempool eviction for obsolete anchors.
4. Enforces correctness of block's Sapling root field
5. Changes miner to correctly apply the Sapling root to the block header
6. Handles mempool consistency checks for anchors
Make some globals static that can be
I wrote this patch as part of making a Bazel build system but it really is independent from that so I'm putting this as a separate PR.
External linkage does not help and just encourages sloppy dependencies (ie using symbols only declared in a cpp file in some other cpp file) and can lead to weird issues when there are name collisions.
Given that in default GetSerializeSize implementations created by
ADD_SERIALIZE_METHODS we're already using CSizeComputer(), get rid
of the specialized GetSerializeSize methods everywhere, and just use
CSizeComputer. This removes a lot of code which isn't actually used
anywhere.
For CCompactSize and CVarInt this actually removes a more efficient
size computing algorithm, which is brought back in a later commit.
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
