New Tipset w/ unit tests (#56)

* Blockchain Interfaces WIP

* Added multihash package to retrieve blake2b hash
* Added sort_key method for Ticket struct
* Added equals method for TipSetKeys struct type
* WIP for Tipset new fn
* WIP cid method for block type which would return CID of block

* New Tipset fn WIP

* Added new conditional checks as per spec update
* WIP sorted and compare logic for ticket size
* Fix cid method for blockHeader
* WIP new fn tests

* Added unit tests

* Added unit tests for tipset methods

* WIP tipset new fn

* Added unit tests

* Added unit tests for tipset methods

* Added tipset new logic

* Added new tipset logic, includes conditional checks and sorting based on ticket size
* Added unit tests for tipset methods
* Added cid fn although it is incomplete as we need cbor encoding

* Fixed equals fn

* Fixed equals fn check
* Linted

* Remove typo

* Made requested changes
* Updated multihash to specific version
* Removed extern crate statement
* Improved commenting
* Updated sort statement
* Improved unit test setup
* Updated error messages for tipset condition checks

* Made requested changes
* Updated cid reference
* Removed pub from mod.rs

* Requested changes made
* Updated error to handle String
* Removed unnecessary import
* Removed sort_key method for Ticket

* Requested changes made
* Removed dead code and unused variable tag

* Remove reverse in sort

* improved tests

.gitignore

@@ -1,3 +1,4 @@
 /target
 **/*.rs.bk
-/Cargo.lock
+/Cargo.lock
+.idea/

blockchain/Cargo.toml

@@ -10,3 +10,4 @@ edition = "2018"
 vm = {path = "../vm"}
 address = {path = "../vm/address"}
 cid = "0.3.1"
+multihash = "0.8.0"

blockchain/src/blocks/block.rs

@@ -2,11 +2,18 @@
 
 use super::ticket::{Ticket, VRFProofIndex};
 use super::TipSetKeys;
+
 use address::Address;
-use cid::Cid;
+use cid::{Cid, Codec, Prefix, Version};
+use multihash::Hash;
 use vm::message::Message;
 
+// DefaultHashFunction represents the default hashing function to use
+// TODO SHOULD BE BLAKE2B
+const DEFAULT_HASH_FUNCTION: Hash = Hash::Keccak256;
+
 /// BlockHeader defines header of a block in the Filecoin blockchain
+#[derive(Clone, Debug)]
 pub struct BlockHeader {
     /// CHAIN LINKING
     ///
@@ -17,23 +24,23 @@ pub struct BlockHeader {
     /// weight is the aggregate chain weight of the parent set
     pub weight: u64,
     /// epoch is the period in which a new block is generated. There may be multiple rounds in an epoch
-    epoch: u64,
+    pub epoch: u64,
     /// height is the block height
     pub height: u64,
 
     /// MINER INFO
     ///
     /// miner_address is the address of the miner actor that mined this block
-    miner_address: Address,
+    pub miner_address: Address,
 
     /// STATE
     ///
     /// messages is the Cid of the root of an array of Messages
-    messages: Cid,
+    pub messages: Cid,
     /// message_receipts is the Cid of the root of an array of MessageReceipts
-    message_receipts: Cid,
+    pub message_receipts: Cid,
     /// state_root is a cid pointer to the state tree after application of the transactions state transitions
-    state_root: Cid,
+    pub state_root: Cid,
 
     /// CONSENSUS
     ///
@@ -43,15 +50,40 @@ pub struct BlockHeader {
     pub ticket: Ticket,
     /// election_proof is the "scratched ticket" proving that this block won
     /// an election
-    election_proof: VRFProofIndex,
+    pub election_proof: VRFProofIndex,
     // SIGNATURES
     //
     // block_sig filCrypto Signature
     // BLSAggregateSig
+    /// CACHE
+    ///
+    pub cached_cid: Cid,
+
+    pub cached_bytes: u8,
 }
 
 /// Block defines a full block
 pub struct Block {
     header: BlockHeader,
     messages: Vec<Message>,
 }
+
+impl BlockHeader {
+    /// cid returns the content id of this header
+    pub fn cid(&mut self) -> Cid {
+        // TODO
+        // Encode blockheader into cache_bytes
+        // Change DEFAULT_HASH_FUNCTION to utilize blake2b
+        //
+        // Currently content id for headers will be incomplete until encoding and supporting libraries are completed
+        let c = Prefix {
+            version: Version::V1,
+            codec: Codec::DagCBOR,
+            mh_type: DEFAULT_HASH_FUNCTION,
+            mh_len: 0,
+        };
+        let new_cid = Cid::new_from_prefix(&c, &[self.cached_bytes]);
+        self.cached_cid = new_cid;
+        self.cached_cid.clone()
+    }
+}

blockchain/src/blocks/errors.rs

@@ -2,14 +2,14 @@ use std::fmt;
 
 #[derive(Debug, PartialEq)]
 pub enum Error {
-    UndefinedTipSet,
+    UndefinedTipSet(String),
     NoBlocks,
 }
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
-            Error::UndefinedTipSet => write!(f, "Undefined tipset"),
+            Error::UndefinedTipSet(ref msg) => write!(f, "Invalid tipset: {}", msg),
             Error::NoBlocks => write!(f, "No blocks for tipset"),
         }
     }

blockchain/src/blocks/ticket.rs

@@ -4,7 +4,7 @@ pub type VRFProofIndex = Vec<u8>;
 /// A Ticket is a marker of a tick of the blockchain's clock.  It is the source
 /// of randomness for proofs of storage and leader election.  It is generated
 /// by the miner of a block using a VRF and a VDF.
-#[derive(Clone)]
+#[derive(Clone, Debug, PartialEq, PartialOrd, Eq)]
 pub struct Ticket {
     /// A proof output by running a VRF on the VDFResult of the parent ticket
     pub vrfproof: VRFProofIndex,