From c1e44e86db929daf9f961597a6c5012a7fad5a8d Mon Sep 17 00:00:00 2001
From: NikVolf <nikvolf@gmail.com>
Date: Mon, 3 Dec 2018 14:29:04 +0300
Subject: [PATCH] canonize/decanonize database update

---
 db/src/block_chain_db.rs | 43 ++++++++++++++++++++++++++++++++++++----
 storage/src/error.rs     |  3 +++
 storage/src/nullifier.rs |  2 +-
 3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/db/src/block_chain_db.rs b/db/src/block_chain_db.rs
index 00b41953..be883aab 100644
--- a/db/src/block_chain_db.rs
+++ b/db/src/block_chain_db.rs
@@ -7,14 +7,15 @@ use bytes::Bytes;
 use primitives::compact::Compact;
 use chain::{
 	IndexedBlock, IndexedBlockHeader, IndexedTransaction, BlockHeader, Block, Transaction,
-	OutPoint, TransactionOutput
+	OutPoint, TransactionOutput, SAPLING_TX_VERSION_GROUP_ID,
 };
 use ser::{
 	deserialize, serialize, List
 };
 use kv::{
 	KeyValueDatabase, OverlayDatabase, Transaction as DBTransaction, Value, DiskDatabase,
-	DatabaseConfig, MemoryDatabase, AutoFlushingOverlayDatabase, KeyValue, Key, KeyState, CacheDatabase
+	DatabaseConfig, MemoryDatabase, AutoFlushingOverlayDatabase, KeyValue, Key, KeyState,
+	CacheDatabase,
 };
 use kv::{
 	COL_COUNT, COL_BLOCK_HASHES, COL_BLOCK_HEADERS, COL_BLOCK_TRANSACTIONS, COL_TRANSACTIONS,
@@ -24,6 +25,7 @@ use storage::{
 	BlockRef, Error, BlockHeaderProvider, BlockProvider, BlockOrigin, TransactionMeta, IndexedBlockProvider,
 	TransactionMetaProvider, TransactionProvider, TransactionOutputProvider, BlockChain, Store,
 	SideChainOrigin, ForkChain, Forkable, CanonStore, ConfigStore, BestBlock, NullifierTracker, Nullifier,
+	NullifierTag,
 };
 
 const KEY_BEST_BLOCK_NUMBER: &'static str = "best_block_number";
@@ -285,8 +287,25 @@ impl<T> BlockChainDatabase<T> where T: KeyValueDatabase {
 		}
 
 		for tx in block.transactions.iter().skip(1) {
+			let is_sapling_group = tx.raw.version_group_id == SAPLING_TX_VERSION_GROUP_ID;
+
 			modified_meta.insert(tx.hash.clone(), TransactionMeta::new(new_best_block.number, tx.raw.outputs.len()));
 
+			if let Some(ref js) = tx.raw.join_split {
+				for js_descriptor in js.descriptions.iter() {
+					for nullifier in &js_descriptor.nullifiers[..] {
+						let nullifier_key = Nullifier::new(
+							if is_sapling_group { NullifierTag::Sapling } else { NullifierTag::Sprout },
+							H256::from(&nullifier[..])
+						);
+						if self.contains_nullifier(nullifier_key) {
+							return Err(Error::CannotCanonize);
+						}
+						update.insert(KeyValue::Nullifier(nullifier_key));
+					}
+				}
+			}
+
 			for input in &tx.raw.inputs {
 				use std::collections::hash_map::Entry;
 
@@ -343,6 +362,22 @@ impl<T> BlockChainDatabase<T> where T: KeyValueDatabase {
 
 		let mut modified_meta: HashMap<H256, TransactionMeta> = HashMap::new();
 		for tx in block.transactions.iter().skip(1) {
+			let is_sapling_group = tx.raw.version_group_id == SAPLING_TX_VERSION_GROUP_ID;
+			if let Some(ref js) = tx.raw.join_split {
+				for js_descriptor in js.descriptions.iter() {
+					for nullifier in &js_descriptor.nullifiers[..] {
+						let nullifier_key = Nullifier::new(
+							if is_sapling_group { NullifierTag::Sapling } else { NullifierTag::Sprout },
+							H256::from(&nullifier[..])
+						);
+						if !self.contains_nullifier(nullifier_key) {
+							return Err(Error::CannotDecanonize);
+						}
+						update.delete(Key::Nullifier(nullifier_key));
+					}
+				}
+			}
+
 			for input in &tx.raw.inputs {
 				use std::collections::hash_map::Entry;
 
@@ -510,8 +545,8 @@ impl<T> TransactionOutputProvider for BlockChainDatabase<T> where T: KeyValueDat
 }
 
 impl<T> NullifierTracker for BlockChainDatabase<T> where T: KeyValueDatabase {
-	fn contains(&self, _nullifier: Nullifier) -> bool {
-		false
+	fn contains_nullifier(&self, nullifier: Nullifier) -> bool {
+		self.get(Key::Nullifier(nullifier)).is_some()
 	}
 }
 
diff --git a/storage/src/error.rs b/storage/src/error.rs
index 0e11a137..43585d89 100644
--- a/storage/src/error.rs
+++ b/storage/src/error.rs
@@ -12,6 +12,9 @@ pub enum Error {
 	/// Ancient fork
 	#[display(fmt = "Fork is too long to proceed")]
 	AncientFork,
+	/// Invalid block
+	#[display(fmt = "Cannot decanonize block (invalid database state)")]
+	CannotDecanonize,
 }
 
 impl From<Error> for String {
diff --git a/storage/src/nullifier.rs b/storage/src/nullifier.rs
index d8909575..f484c54f 100644
--- a/storage/src/nullifier.rs
+++ b/storage/src/nullifier.rs
@@ -21,7 +21,7 @@ pub struct Nullifier {
 
 /// Trait to query existing nullifier.
 pub trait NullifierTracker {
-    fn contains(&self, nullifier: Nullifier) -> bool;
+    fn contains_nullifier(&self, nullifier: Nullifier) -> bool;
 }
 
 impl Nullifier {