Add 'zcash_history/' from commit 'e2c131fdc308265adcab774e54d4d5804c23b368'

git-subtree-dir: zcash_history
git-subtree-mainline: be0ee9eb82
git-subtree-split: e2c131fdc3

zcash_history/src/node_data.rs

@@ -0,0 +1,239 @@
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt, ByteOrder};
+use bigint::U256;
+use blake2::Params as Blake2Params;
+
+/// Maximum serialized size of the node metadata.
+pub const MAX_NODE_DATA_SIZE: usize =
+    32 + // subtree commitment
+    4 +  // start time
+    4 +  // end time
+    4 +  // start target
+    4 +  // end target
+    32 + // start sapling tree root
+    32 + // end sapling tree root
+    32 + // subtree total work
+    9 +  // start height (compact uint)
+    9 +  // end height (compact uint)
+    9;   // shielded tx count (compact uint)
+    // = total of 171
+
+/// Node metadata.
+#[repr(C)]
+#[derive(Debug, Clone, Default)]
+#[cfg_attr(test, derive(PartialEq))]
+pub struct NodeData {
+    /// Consensus branch id, should be provided by deserializing node.
+    pub consensus_branch_id: u32,
+    /// Subtree commitment - either block hash for leaves or hashsum of children for nodes.
+    pub subtree_commitment: [u8; 32],
+    /// Start time.
+    pub start_time: u32,
+    /// End time.
+    pub end_time: u32,
+    /// Start target.
+    pub start_target: u32,
+    /// End target.
+    pub end_target: u32,
+    /// Start sapling tree root.
+    pub start_sapling_root: [u8; 32],
+    /// End sapling tree root.
+    pub end_sapling_root: [u8; 32],
+    /// Part of tree total work.
+    pub subtree_total_work: U256,
+    /// Start height.
+    pub start_height: u64,
+    /// End height
+    pub end_height: u64,
+    /// Number of shielded transactions.
+    pub shielded_tx: u64,
+}
+
+fn blake2b_personal(personalization: &[u8], input: &[u8]) -> [u8; 32] {
+    let hash_result = Blake2Params::new()
+        .hash_length(32)
+        .personal(personalization)
+        .to_state()
+        .update(input)
+        .finalize();
+    let mut result = [0u8; 32];
+    result.copy_from_slice(hash_result.as_bytes());
+    result
+}
+
+fn personalization(branch_id: u32) -> [u8; 16] {
+    let mut result = [0u8; 16];
+    result[..12].copy_from_slice(b"ZcashHistory");
+    LittleEndian::write_u32(&mut result[12..], branch_id);
+    result
+}
+
+impl NodeData {
+    /// Combine two nodes metadata.
+    pub fn combine(left: &NodeData, right: &NodeData) -> NodeData {
+        assert_eq!(left.consensus_branch_id, right.consensus_branch_id);
+
+        let mut hash_buf = [0u8; MAX_NODE_DATA_SIZE * 2];
+        let size = {
+            let mut cursor = ::std::io::Cursor::new(&mut hash_buf[..]);
+            left.write(&mut cursor).expect("Writing to memory buf with enough length cannot fail; qed");
+            right.write(&mut cursor).expect("Writing to memory buf with enough length cannot fail; qed");
+            cursor.position() as usize
+        };
+
+        let hash = blake2b_personal(
+            &personalization(left.consensus_branch_id),
+            &hash_buf[..size]
+        );
+
+        NodeData {
+            consensus_branch_id: left.consensus_branch_id,
+            subtree_commitment: hash,
+            start_time: left.start_time,
+            end_time: right.end_time,
+            start_target: left.start_target,
+            end_target: right.end_target,
+            start_sapling_root: left.start_sapling_root,
+            end_sapling_root: right.end_sapling_root,
+            subtree_total_work: left.subtree_total_work + right.subtree_total_work,
+            start_height: left.start_height,
+            end_height: right.end_height,
+            shielded_tx: left.shielded_tx + right.shielded_tx,
+        }
+    }
+
+    fn write_compact<W: std::io::Write>(w: &mut W, compact: u64) -> std::io::Result<()> {
+        match compact {
+            0..=0xfc => {
+                w.write_all(&[compact as u8])?
+            },
+            0xfd..=0xffff => {
+                w.write_all(&[0xfd])?;
+                w.write_u16::<LittleEndian>(compact as u16)?;
+            },
+            0x10000..=0xffff_ffff => {
+                w.write_all(&[0xfe])?;
+                w.write_u32::<LittleEndian>(compact as u32)?;
+            },
+            _ => {
+                w.write_all(&[0xff])?;
+                w.write_u64::<LittleEndian>(compact)?;
+            }
+        }
+        Ok(())
+    }
+
+    fn read_compact<R: std::io::Read>(reader: &mut R) -> std::io::Result<u64> {
+        let result = match reader.read_u8()? {
+            i @ 0..=0xfc => i.into(),
+            0xfd => reader.read_u16::<LittleEndian>()?.into(),
+            0xfe => reader.read_u32::<LittleEndian>()?.into(),
+            _ => reader.read_u64::<LittleEndian>()?,
+        };
+
+        Ok(result)
+    }
+
+    /// Write to the byte representation.
+    pub fn write<W: std::io::Write>(&self, w: &mut W) -> std::io::Result<()> {
+        w.write_all(&self.subtree_commitment)?;
+        w.write_u32::<LittleEndian>(self.start_time)?;
+        w.write_u32::<LittleEndian>(self.end_time)?;
+        w.write_u32::<LittleEndian>(self.start_target)?;
+        w.write_u32::<LittleEndian>(self.end_target)?;
+        w.write_all(&self.start_sapling_root)?;
+        w.write_all(&self.end_sapling_root)?;
+
+        let mut work_buf = [0u8; 32];
+        self.subtree_total_work.to_little_endian(&mut work_buf[..]);
+        w.write_all(&work_buf)?;
+
+        Self::write_compact(w, self.start_height)?;
+        Self::write_compact(w, self.end_height)?;
+        Self::write_compact(w, self.shielded_tx)?;
+        Ok(())
+    }
+
+    /// Read from the byte representation.
+    pub fn read<R: std::io::Read>(consensus_branch_id: u32, r: &mut R) -> std::io::Result<Self> {
+        let mut data = Self::default();
+        data.consensus_branch_id = consensus_branch_id;
+        r.read_exact(&mut data.subtree_commitment)?;
+        data.start_time = r.read_u32::<LittleEndian>()?;
+        data.end_time = r.read_u32::<LittleEndian>()?;
+        data.start_target= r.read_u32::<LittleEndian>()?;
+        data.end_target= r.read_u32::<LittleEndian>()?;
+        r.read_exact(&mut data.start_sapling_root)?;
+        r.read_exact(&mut data.end_sapling_root)?;
+
+        let mut work_buf = [0u8; 32];
+        r.read_exact(&mut work_buf)?;
+        data.subtree_total_work = U256::from_little_endian(&work_buf);
+
+        data.start_height = Self::read_compact(r)?;
+        data.end_height = Self::read_compact(r)?;
+        data.shielded_tx = Self::read_compact(r)?;
+
+        Ok(data)
+    }
+
+    /// Convert to byte representation.
+    pub fn to_bytes(&self) -> Vec<u8> {
+        let mut buf = [0u8; MAX_NODE_DATA_SIZE];
+        let pos = {
+            let mut cursor = std::io::Cursor::new(&mut buf[..]);
+            self.write(&mut cursor).expect("Cursor cannot fail");
+            cursor.position() as usize
+        };
+
+        buf[0..pos].to_vec()
+    }
+
+    /// Convert from byte representation.
+    pub fn from_bytes<T: AsRef<[u8]>>(consensus_branch_id: u32, buf: T) -> std::io::Result<Self> {
+        let mut cursor = std::io::Cursor::new(buf);
+        Self::read(consensus_branch_id, &mut cursor)
+    }
+
+    /// Hash node metadata
+    pub fn hash(&self) -> [u8; 32] {
+        let bytes = self.to_bytes();
+
+        blake2b_personal(&personalization(self.consensus_branch_id), &bytes)
+    }
+}
+
+#[cfg(test)]
+impl quickcheck::Arbitrary for NodeData {
+    fn arbitrary<G: quickcheck::Gen>(gen: &mut G) -> Self {
+        let mut node_data = NodeData::default();
+        node_data.consensus_branch_id = 0;
+        gen.fill_bytes(&mut node_data.subtree_commitment[..]);
+        node_data.start_time = gen.next_u32();
+        node_data.end_time = gen.next_u32();
+        node_data.start_target = gen.next_u32();
+        node_data.end_target = gen.next_u32();
+        gen.fill_bytes(&mut node_data.start_sapling_root[..]);
+        gen.fill_bytes(&mut node_data.end_sapling_root[..]);
+        let mut number = [0u8; 32];
+        gen.fill_bytes(&mut number[..]);
+        node_data.subtree_total_work = U256::from_little_endian(&number[..]);
+        node_data.start_height = gen.next_u64();
+        node_data.end_height = gen.next_u64();
+        node_data.shielded_tx = gen.next_u64();
+
+        node_data
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::NodeData;
+    use quickcheck::{quickcheck, TestResult};
+
+
+    quickcheck! {
+        fn serialization_round_trip(node_data: NodeData) -> TestResult {
+            TestResult::from_bool(NodeData::from_bytes(0, &node_data.to_bytes()).unwrap() == node_data)
+        }
+    }
+}