Block and BlockHeader types

zebra-chain/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-sha2 = "0.8"
 byteorder = "1.3"
-failure = "0.1"
+chrono = "0.4"
+failure = "0.1"
+sha2 = "0.8"

zebra-chain/src/block.rs

@@ -1,6 +1,66 @@
 //! Definitions of block datastructures.
 
+use crate::transaction::Transaction;
+use chrono::{DateTime, Utc};
+
+/// Block header
+pub struct BlockHeader {
+    /// A SHA-256d hash in internal byte order of the previous block’s
+    /// header. This ensures no previous block can be changed without
+    /// also changing this block’s header .
+    previous_block_hash: [u8; 32],
+
+    /// A SHA-256d hash in internal byte order. The merkle root is
+    /// derived from the hashes of all transactions included in this
+    /// block, ensuring that none of those transactions can be modied
+    /// without modifying the header.
+    merkle_root_hash: [u8; 32],
+
+    /// [Sapling onward] The root LEBS2OSP256(rt) of the Sapling note
+    /// commitment tree corresponding to the nal Sapling treestate of
+    /// this block.
+    // TODO: replace type with custom SaplingRoot or similar type
+    // hash_final_sapling_root: [u8; 32],
+
+    /// The block timestamp is a Unix epoch time (UTC) when the miner
+    /// started hashing the header (according to the miner).
+    time: DateTime<Utc>,
+
+    /// An encoded version of the target threshold this block’s header
+    /// hash must be less than or equal to, in the same nBits format
+    /// used by Bitcoin.
+    ///
+    /// For a block at block height height, bits MUST be equal to
+    /// ThresholdBits(height).
+    ///
+    /// [Bitcoin-nBits](https://bitcoin.org/en/developer-reference#target-nbits)
+    // pzec has their own wrapper around u32 for this field:
+    // https://github.com/ZcashFoundation/zebra/blob/master/zebra-primitives/src/compact.rs
+    bits: u32,
+
+    /// An arbitrary field that miners can change to modify the header
+    /// hash in order to produce a hash less than or equal to the
+    /// target threshold.
+    nonce: [u8; 32],
+
+    /// The Equihash solution.
+    // The solution size when serialized should be in bytes ('always 1344').
+    solution: [u8; 1344],
+}
+
+impl BlockHeader {
+    /// Get the SHA-256d hash in internal byte order of this block header.
+    pub fn hash(&self) -> [u8; 32] {
+        unimplemented!();
+    }
+}
+
 /// A block in your blockchain.
-pub struct Block {}
+pub struct Block {
+    /// First 80 bytes of the block as defined by the encoding used by
+    /// "block" messages
+    pub header: BlockHeader,
 
-impl Block {}
+    ///
+    pub transactions: Vec<Transaction>,
+}

zebra-network/src/message.rs

@@ -142,7 +142,13 @@ pub enum Message {
     /// A `block` message.
     ///
     /// [Bitcoin reference](https://en.bitcoin.it/wiki/Protocol_documentation#block)
-    Block {/* XXX add fields */},
+    Block {
+        /// The block version number indicates which set of block
+        /// validation rules to follow. The current and only dened
+        /// block version number for Zcash is 4.
+        version: Version,
+        // XXX incomplete
+    },
 
     /// A `getblocks` message.
     ///