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//! Network upgrade consensus parameters for Zcash.
use NetworkUpgrade::*;
use crate::block;
use crate::parameters::{Network, Network::*};
use std::collections::{BTreeMap, HashMap};
use std::fmt;
use chrono::{DateTime, Duration, Utc};
use hex::{FromHex, ToHex};
#[cfg(any(test, feature = "proptest-impl"))]
use proptest_derive::Arbitrary;
/// A list of network upgrades in the order that they must be activated.
pub const NETWORK_UPGRADES_IN_ORDER: [NetworkUpgrade; 9] = [
Genesis,
BeforeOverwinter,
Overwinter,
Sapling,
Blossom,
Heartwood,
Canopy,
Nu5,
Nu6,
];
/// A Zcash network upgrade.
///
/// Network upgrades change the Zcash network protocol or consensus rules. Note that they have no
/// designated codenames from NU5 onwards.
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize, Ord, PartialOrd)]
#[cfg_attr(any(test, feature = "proptest-impl"), derive(Arbitrary))]
pub enum NetworkUpgrade {
/// The Zcash protocol for a Genesis block.
///
/// Zcash genesis blocks use a different set of consensus rules from
/// other BeforeOverwinter blocks, so we treat them like a separate network
/// upgrade.
Genesis,
/// The Zcash protocol before the Overwinter upgrade.
///
/// We avoid using `Sprout`, because the specification says that Sprout
/// is the name of the pre-Sapling protocol, before and after Overwinter.
BeforeOverwinter,
/// The Zcash protocol after the Overwinter upgrade.
Overwinter,
/// The Zcash protocol after the Sapling upgrade.
Sapling,
/// The Zcash protocol after the Blossom upgrade.
Blossom,
/// The Zcash protocol after the Heartwood upgrade.
Heartwood,
/// The Zcash protocol after the Canopy upgrade.
Canopy,
/// The Zcash protocol after the NU5 upgrade.
#[serde(rename = "NU5")]
Nu5,
/// The Zcash protocol after the NU6 upgrade.
Nu6,
}
impl fmt::Display for NetworkUpgrade {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
// Same as the debug representation for now
fmt::Debug::fmt(self, f)
}
}
/// Mainnet network upgrade activation heights.
///
/// This is actually a bijective map, but it is const, so we use a vector, and
/// do the uniqueness check in the unit tests.
///
/// # Correctness
///
/// Don't use this directly; use NetworkUpgrade::activation_list() so that
/// we can switch to fake activation heights for some tests.
#[allow(unused)]
pub(super) const MAINNET_ACTIVATION_HEIGHTS: &[(block::Height, NetworkUpgrade)] = &[
(block::Height(0), Genesis),
(block::Height(1), BeforeOverwinter),
(block::Height(347_500), Overwinter),
(block::Height(419_200), Sapling),
(block::Height(653_600), Blossom),
(block::Height(903_000), Heartwood),
(block::Height(1_046_400), Canopy),
(block::Height(1_687_104), Nu5),
// TODO: Add NU6
// (block::Height(2_726_400), Nu6),
];
/// Fake mainnet network upgrade activation heights, used in tests.
#[allow(unused)]
const FAKE_MAINNET_ACTIVATION_HEIGHTS: &[(block::Height, NetworkUpgrade)] = &[
(block::Height(0), Genesis),
(block::Height(5), BeforeOverwinter),
(block::Height(10), Overwinter),
(block::Height(15), Sapling),
(block::Height(20), Blossom),
(block::Height(25), Heartwood),
(block::Height(30), Canopy),
(block::Height(35), Nu5),
(block::Height(40), Nu6),
];
/// Testnet network upgrade activation heights.
///
/// This is actually a bijective map, but it is const, so we use a vector, and
/// do the uniqueness check in the unit tests.
///
/// # Correctness
///
/// Don't use this directly; use NetworkUpgrade::activation_list() so that
/// we can switch to fake activation heights for some tests.
#[allow(unused)]
pub(super) const TESTNET_ACTIVATION_HEIGHTS: &[(block::Height, NetworkUpgrade)] = &[
(block::Height(0), Genesis),
(block::Height(1), BeforeOverwinter),
(block::Height(207_500), Overwinter),
(block::Height(280_000), Sapling),
(block::Height(584_000), Blossom),
(block::Height(903_800), Heartwood),
(block::Height(1_028_500), Canopy),
(block::Height(1_842_420), Nu5),
(block::Height(2_976_000), Nu6),
];
/// Fake testnet network upgrade activation heights, used in tests.
#[allow(unused)]
const FAKE_TESTNET_ACTIVATION_HEIGHTS: &[(block::Height, NetworkUpgrade)] = &[
(block::Height(0), Genesis),
(block::Height(5), BeforeOverwinter),
(block::Height(10), Overwinter),
(block::Height(15), Sapling),
(block::Height(20), Blossom),
(block::Height(25), Heartwood),
(block::Height(30), Canopy),
(block::Height(35), Nu5),
(block::Height(40), Nu6),
];
/// The Consensus Branch Id, used to bind transactions and blocks to a
/// particular network upgrade.
#[derive(Copy, Clone, Debug, Default, Eq, Hash, PartialEq, Serialize, Deserialize)]
pub struct ConsensusBranchId(pub(crate) u32);
impl ConsensusBranchId {
/// Return the hash bytes in big-endian byte-order suitable for printing out byte by byte.
///
/// Zebra displays consensus branch IDs in big-endian byte-order,
/// following the convention set by zcashd.
fn bytes_in_display_order(&self) -> [u8; 4] {
self.0.to_be_bytes()
}
}
impl From<ConsensusBranchId> for u32 {
fn from(branch: ConsensusBranchId) -> u32 {
branch.0
}
}
impl ToHex for &ConsensusBranchId {
fn encode_hex<T: FromIterator<char>>(&self) -> T {
self.bytes_in_display_order().encode_hex()
}
fn encode_hex_upper<T: FromIterator<char>>(&self) -> T {
self.bytes_in_display_order().encode_hex_upper()
}
}
impl ToHex for ConsensusBranchId {
fn encode_hex<T: FromIterator<char>>(&self) -> T {
self.bytes_in_display_order().encode_hex()
}
fn encode_hex_upper<T: FromIterator<char>>(&self) -> T {
self.bytes_in_display_order().encode_hex_upper()
}
}
impl FromHex for ConsensusBranchId {
type Error = <[u8; 4] as FromHex>::Error;
fn from_hex<T: AsRef<[u8]>>(hex: T) -> Result<Self, Self::Error> {
let branch = <[u8; 4]>::from_hex(hex)?;
Ok(ConsensusBranchId(u32::from_be_bytes(branch)))
}
}
impl fmt::Display for ConsensusBranchId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(&self.encode_hex::<String>())
}
}
/// Network Upgrade Consensus Branch Ids.
///
/// Branch ids are the same for mainnet and testnet. If there is a testnet
/// rollback after a bug, the branch id changes.
///
/// Branch ids were introduced in the Overwinter upgrade, so there are no
/// Genesis or BeforeOverwinter branch ids.
///
/// This is actually a bijective map, but it is const, so we use a vector, and
/// do the uniqueness check in the unit tests.
pub(crate) const CONSENSUS_BRANCH_IDS: &[(NetworkUpgrade, ConsensusBranchId)] = &[
(Overwinter, ConsensusBranchId(0x5ba81b19)),
(Sapling, ConsensusBranchId(0x76b809bb)),
(Blossom, ConsensusBranchId(0x2bb40e60)),
(Heartwood, ConsensusBranchId(0xf5b9230b)),
(Canopy, ConsensusBranchId(0xe9ff75a6)),
(Nu5, ConsensusBranchId(0xc2d6d0b4)),
(Nu6, ConsensusBranchId(0xc8e71055)),
];
/// The target block spacing before Blossom.
const PRE_BLOSSOM_POW_TARGET_SPACING: i64 = 150;
/// The target block spacing after Blossom activation.
pub const POST_BLOSSOM_POW_TARGET_SPACING: u32 = 75;
/// The averaging window for difficulty threshold arithmetic mean calculations.
///
/// `PoWAveragingWindow` in the Zcash specification.
pub const POW_AVERAGING_WINDOW: usize = 17;
/// The multiplier used to derive the testnet minimum difficulty block time gap
/// threshold.
///
/// Based on <https://zips.z.cash/zip-0208#minimum-difficulty-blocks-on-the-test-network>
const TESTNET_MINIMUM_DIFFICULTY_GAP_MULTIPLIER: i32 = 6;
/// The start height for the testnet minimum difficulty consensus rule.
///
/// Based on <https://zips.z.cash/zip-0208#minimum-difficulty-blocks-on-the-test-network>
const TESTNET_MINIMUM_DIFFICULTY_START_HEIGHT: block::Height = block::Height(299_188);
/// The activation height for the block maximum time rule on Testnet.
///
/// Part of the block header consensus rules in the Zcash specification at
/// <https://zips.z.cash/protocol/protocol.pdf#blockheader>
pub const TESTNET_MAX_TIME_START_HEIGHT: block::Height = block::Height(653_606);
impl Network {
/// Returns a map between activation heights and network upgrades for `network`,
/// in ascending height order.
///
/// If the activation height of a future upgrade is not known, that
/// network upgrade does not appear in the list.
///
/// This is actually a bijective map.
///
/// When the environment variable TEST_FAKE_ACTIVATION_HEIGHTS is set
/// and it's a test build, this returns a list of fake activation heights
/// used by some tests.
///
/// Note: This skips implicit network upgrade activations, use [`Network::full_activation_list`]
/// to get an explicit list of all network upgrade activations.
pub fn activation_list(&self) -> BTreeMap<block::Height, NetworkUpgrade> {
match self {
// To prevent accidentally setting this somehow, only check the env var
// when being compiled for tests. We can't use cfg(test) since the
// test that uses this is in zebra-state, and cfg(test) is not
// set for dependencies. However, zebra-state does set the
// zebra-test feature of zebra-chain if it's a dev dependency.
//
// Cargo features are additive, so all test binaries built along with
// zebra-state will have this feature enabled. But we are using
// Rust Edition 2021 and Cargo resolver version 2, so the "zebra-test"
// feature should only be enabled for tests:
// https://doc.rust-lang.org/cargo/reference/features.html#resolver-version-2-command-line-flags
#[cfg(feature = "zebra-test")]
Mainnet if std::env::var_os("TEST_FAKE_ACTIVATION_HEIGHTS").is_some() => {
FAKE_MAINNET_ACTIVATION_HEIGHTS.iter().cloned().collect()
}
#[cfg(feature = "zebra-test")]
Testnet(_) if std::env::var_os("TEST_FAKE_ACTIVATION_HEIGHTS").is_some() => {
FAKE_TESTNET_ACTIVATION_HEIGHTS.iter().cloned().collect()
}
Mainnet => MAINNET_ACTIVATION_HEIGHTS.iter().cloned().collect(),
Testnet(params) => params.activation_heights().clone(),
}
}
/// Returns a vector of all implicit and explicit network upgrades for `network`,
/// in ascending height order.
pub fn full_activation_list(&self) -> Vec<(block::Height, NetworkUpgrade)> {
NETWORK_UPGRADES_IN_ORDER
.into_iter()
.map_while(|nu| Some((NetworkUpgrade::activation_height(&nu, self)?, nu)))
.collect()
}
}
impl NetworkUpgrade {
/// Returns the current network upgrade and its activation height for `network` and `height`.
pub fn current_with_activation_height(
network: &Network,
height: block::Height,
) -> (NetworkUpgrade, block::Height) {
network
.activation_list()
.range(..=height)
.map(|(&h, &nu)| (nu, h))
.next_back()
.expect("every height has a current network upgrade")
}
/// Returns the current network upgrade for `network` and `height`.
pub fn current(network: &Network, height: block::Height) -> NetworkUpgrade {
network
.activation_list()
.range(..=height)
.map(|(_, nu)| *nu)
.next_back()
.expect("every height has a current network upgrade")
}
/// Returns the next expected network upgrade after this network upgrade
pub fn next_upgrade(self) -> Option<Self> {
match self {
Genesis => Some(BeforeOverwinter),
BeforeOverwinter => Some(Overwinter),
Overwinter => Some(Sapling),
Sapling => Some(Blossom),
Blossom => Some(Heartwood),
Heartwood => Some(Canopy),
Canopy => Some(Nu5),
Nu5 => Some(Nu6),
Nu6 => None,
}
}
/// Returns the next network upgrade for `network` and `height`.
///
/// Returns None if the next upgrade has not been implemented in Zebra
/// yet.
#[cfg(test)]
pub fn next(network: &Network, height: block::Height) -> Option<NetworkUpgrade> {
use std::ops::Bound::*;
network
.activation_list()
.range((Excluded(height), Unbounded))
.map(|(_, nu)| *nu)
.next()
}
/// Returns the activation height for this network upgrade on `network`, or
///
/// Returns the activation height of the first network upgrade that follows
/// this network upgrade if there is no activation height for this network upgrade
/// such as on Regtest or a configured Testnet where multiple network upgrades have the
/// same activation height, or if one is omitted when others that follow it are included.
///
/// Returns None if this network upgrade is a future upgrade, and its
/// activation height has not been set yet.
///
/// Returns None if this network upgrade has not been configured on a Testnet or Regtest.
pub fn activation_height(&self, network: &Network) -> Option<block::Height> {
network
.activation_list()
.iter()
.find(|(_, nu)| nu == &self)
.map(|(height, _)| *height)
.or_else(|| {
self.next_upgrade()
.and_then(|next_nu| next_nu.activation_height(network))
})
}
/// Returns `true` if `height` is the activation height of any network upgrade
/// on `network`.
///
/// Use [`NetworkUpgrade::activation_height`] to get the specific network
/// upgrade.
pub fn is_activation_height(network: &Network, height: block::Height) -> bool {
network.activation_list().contains_key(&height)
}
/// Returns an unordered mapping between NetworkUpgrades and their ConsensusBranchIds.
///
/// Branch ids are the same for mainnet and testnet.
///
/// If network upgrade does not have a branch id, that network upgrade does
/// not appear in the list.
///
/// This is actually a bijective map.
pub(crate) fn branch_id_list() -> HashMap<NetworkUpgrade, ConsensusBranchId> {
CONSENSUS_BRANCH_IDS.iter().cloned().collect()
}
/// Returns the consensus branch id for this network upgrade.
///
/// Returns None if this network upgrade has no consensus branch id.
pub fn branch_id(&self) -> Option<ConsensusBranchId> {
NetworkUpgrade::branch_id_list().get(self).cloned()
}
/// Returns the target block spacing for the network upgrade.
///
/// Based on [`PRE_BLOSSOM_POW_TARGET_SPACING`] and
/// [`POST_BLOSSOM_POW_TARGET_SPACING`] from the Zcash specification.
pub fn target_spacing(&self) -> Duration {
let spacing_seconds = match self {
Genesis | BeforeOverwinter | Overwinter | Sapling => PRE_BLOSSOM_POW_TARGET_SPACING,
Blossom | Heartwood | Canopy | Nu5 | Nu6 => POST_BLOSSOM_POW_TARGET_SPACING.into(),
};
Duration::seconds(spacing_seconds)
}
/// Returns the target block spacing for `network` and `height`.
///
/// See [`NetworkUpgrade::target_spacing`] for details.
pub fn target_spacing_for_height(network: &Network, height: block::Height) -> Duration {
NetworkUpgrade::current(network, height).target_spacing()
}
/// Returns all the target block spacings for `network` and the heights where they start.
pub fn target_spacings(
network: &Network,
) -> impl Iterator<Item = (block::Height, Duration)> + '_ {
[
(NetworkUpgrade::Genesis, PRE_BLOSSOM_POW_TARGET_SPACING),
(
NetworkUpgrade::Blossom,
POST_BLOSSOM_POW_TARGET_SPACING.into(),
),
]
.into_iter()
.filter_map(move |(upgrade, spacing_seconds)| {
let activation_height = upgrade.activation_height(network)?;
let target_spacing = Duration::seconds(spacing_seconds);
Some((activation_height, target_spacing))
})
}
/// Returns the minimum difficulty block spacing for `network` and `height`.
/// Returns `None` if the testnet minimum difficulty consensus rule is not active.
///
/// Based on <https://zips.z.cash/zip-0208#minimum-difficulty-blocks-on-the-test-network>
pub fn minimum_difficulty_spacing_for_height(
network: &Network,
height: block::Height,
) -> Option<Duration> {
match (network, height) {
// TODO: Move `TESTNET_MINIMUM_DIFFICULTY_START_HEIGHT` to a field on testnet::Parameters (#8364)
(Network::Testnet(_params), height)
if height < TESTNET_MINIMUM_DIFFICULTY_START_HEIGHT =>
{
None
}
(Network::Mainnet, _) => None,
(Network::Testnet(_params), _) => {
let network_upgrade = NetworkUpgrade::current(network, height);
Some(network_upgrade.target_spacing() * TESTNET_MINIMUM_DIFFICULTY_GAP_MULTIPLIER)
}
}
}
/// Returns true if the gap between `block_time` and `previous_block_time` is
/// greater than the Testnet minimum difficulty time gap. This time gap
/// depends on the `network` and `block_height`.
///
/// Returns false on Mainnet, when `block_height` is less than the minimum
/// difficulty start height, and when the time gap is too small.
///
/// `block_time` can be less than, equal to, or greater than
/// `previous_block_time`, because block times are provided by miners.
///
/// Implements the Testnet minimum difficulty adjustment from ZIPs 205 and 208.
///
/// Spec Note: Some parts of ZIPs 205 and 208 previously specified an incorrect
/// check for the time gap. This function implements the correct "greater than"
/// check.
pub fn is_testnet_min_difficulty_block(
network: &Network,
block_height: block::Height,
block_time: DateTime<Utc>,
previous_block_time: DateTime<Utc>,
) -> bool {
let block_time_gap = block_time - previous_block_time;
if let Some(min_difficulty_gap) =
NetworkUpgrade::minimum_difficulty_spacing_for_height(network, block_height)
{
block_time_gap > min_difficulty_gap
} else {
false
}
}
/// Returns the averaging window timespan for the network upgrade.
///
/// `AveragingWindowTimespan` from the Zcash specification.
pub fn averaging_window_timespan(&self) -> Duration {
self.target_spacing() * POW_AVERAGING_WINDOW.try_into().expect("fits in i32")
}
/// Returns the averaging window timespan for `network` and `height`.
///
/// See [`NetworkUpgrade::averaging_window_timespan`] for details.
pub fn averaging_window_timespan_for_height(
network: &Network,
height: block::Height,
) -> Duration {
NetworkUpgrade::current(network, height).averaging_window_timespan()
}
/// Returns the NetworkUpgrade given an u32 as ConsensusBranchId
pub fn from_branch_id(branch_id: u32) -> Option<NetworkUpgrade> {
CONSENSUS_BRANCH_IDS
.iter()
.find(|id| id.1 == ConsensusBranchId(branch_id))
.map(|nu| nu.0)
}
}
impl From<zcash_protocol::consensus::NetworkUpgrade> for NetworkUpgrade {
fn from(nu: zcash_protocol::consensus::NetworkUpgrade) -> Self {
match nu {
zcash_protocol::consensus::NetworkUpgrade::Overwinter => Self::Overwinter,
zcash_protocol::consensus::NetworkUpgrade::Sapling => Self::Sapling,
zcash_protocol::consensus::NetworkUpgrade::Blossom => Self::Blossom,
zcash_protocol::consensus::NetworkUpgrade::Heartwood => Self::Heartwood,
zcash_protocol::consensus::NetworkUpgrade::Canopy => Self::Canopy,
zcash_protocol::consensus::NetworkUpgrade::Nu5 => Self::Nu5,
zcash_protocol::consensus::NetworkUpgrade::Nu6 => Self::Nu6,
}
}
}
impl ConsensusBranchId {
/// The value used by `zcashd` RPCs for missing consensus branch IDs.
///
/// # Consensus
///
/// This value must only be used in RPCs.
///
/// The consensus rules handle missing branch IDs by rejecting blocks and transactions,
/// so this substitute value must not be used in consensus-critical code.
pub const RPC_MISSING_ID: ConsensusBranchId = ConsensusBranchId(0);
/// Returns the current consensus branch id for `network` and `height`.
///
/// Returns None if the network has no branch id at this height.
pub fn current(network: &Network, height: block::Height) -> Option<ConsensusBranchId> {
NetworkUpgrade::current(network, height).branch_id()
}
}