Implement account interface and block interface

Author: hayesgm

lib/blockchain/account.ex

@@ -471,7 +471,7 @@ defmodule Blockchain.Account do
       ...> |> Blockchain.Account.get_machine_code(<<0x01::160>>)
       {:ok, <<1, 2, 3>>}
   """
-  @spec get_machine_code(EVM.state, EVM.address) :: {:ok, EVM.MachineState.t} | :not_found
+  @spec get_machine_code(EVM.state, EVM.address) :: {:ok, binary()} | :not_found
   def get_machine_code(state, contract_address) do
     # TODO: Do we have a standard for default account values
     account = get_account(state, contract_address) || %__MODULE__{}

lib/blockchain/block.ex

@@ -112,7 +112,7 @@ defmodule Blockchain.Block do
 
   @doc """
   Computes hash of a block, which is simply the hash of the serialized
-  block after apply RLP.
+  block after applying RLP encoding.
 
   This is defined in Eq.(37) of the Yellow Paper.
 
@@ -128,7 +128,7 @@ defmodule Blockchain.Block do
   """
   @spec hash(t) :: EVM.hash
   def hash(block) do
-    block.header |> Header.serialize() |> ExRLP.encode |> BitHelper.kec
+    block.header |> Header.hash
   end
 
   @doc """
@@ -191,6 +191,84 @@ defmodule Blockchain.Block do
     end
   end
 
+  @doc """
+  Returns a given block from the database, if the hash
+  exists in the database.
+
+  See `Blockchain.Block.put_block/2` for details.
+
+  ## Examples
+
+      # Legit, current block
+      iex> db = MerklePatriciaTree.Test.random_ets_db()
+      iex> block = %Blockchain.Block{
+      ...>   transactions: [%Blockchain.Transaction{nonce: 5, gas_price: 6, gas_limit: 7, to: <<1::160>>, value: 8, v: 27, r: 9, s: 10, data: "hi"}],
+      ...>   header: %Block.Header{number: 5, parent_hash: <<1, 2, 3>>, beneficiary: <<2, 3, 4>>, difficulty: 100, timestamp: 11, mix_hash: <<1>>, nonce: <<2>>}
+      ...> }
+      iex> Blockchain.Block.put_block(block, db)
+      iex> Blockchain.Block.get_block_hash_by_steps(block |> Blockchain.Block.hash, 0, db)
+      {:ok, <<78, 28, 127, 10, 192, 253, 127, 239, 254, 179, 39, 34, 245, 44,
+             152, 98, 128, 71, 238, 155, 100, 161, 199, 71, 243, 223, 172, 191,
+             74, 99, 128, 63>>}
+
+      # Bad, in the future
+      iex> db = MerklePatriciaTree.Test.random_ets_db()
+      iex> block = %Blockchain.Block{
+      ...>   transactions: [%Blockchain.Transaction{nonce: 5, gas_price: 6, gas_limit: 7, to: <<1::160>>, value: 8, v: 27, r: 9, s: 10, data: "hi"}],
+      ...>   header: %Block.Header{number: 5, parent_hash: <<1, 2, 3>>, beneficiary: <<2, 3, 4>>, difficulty: 100, timestamp: 11, mix_hash: <<1>>, nonce: <<2>>}
+      ...> }
+      iex> Blockchain.Block.put_block(block, db)
+      iex> Blockchain.Block.get_block_hash_by_steps(block |> Blockchain.Block.hash, -1, db)
+      :not_found
+
+      # Bad, before the dawn of time
+      iex> db = MerklePatriciaTree.Test.random_ets_db()
+      iex> block = %Blockchain.Block{
+      ...>   transactions: [%Blockchain.Transaction{nonce: 5, gas_price: 6, gas_limit: 7, to: <<1::160>>, value: 8, v: 27, r: 9, s: 10, data: "hi"}],
+      ...>   header: %Block.Header{number: 5, parent_hash: <<1, 2, 3>>, beneficiary: <<2, 3, 4>>, difficulty: 100, timestamp: 11, mix_hash: <<1>>, nonce: <<2>>}
+      ...> }
+      iex> Blockchain.Block.put_block(block, db)
+      iex> Blockchain.Block.get_block_hash_by_steps(block |> Blockchain.Block.hash, 6, db)
+      :not_found
+
+      iex> Blockchain.Block.get_block_hash_by_steps(<<1, 2, 3>>, 0, nil)
+      {:ok, <<1, 2, 3>>}
+
+      # Legit, back zero and one
+      iex> db = MerklePatriciaTree.Test.random_ets_db()
+      iex> block_1 = %Blockchain.Block{
+      ...>   transactions: [%Blockchain.Transaction{nonce: 5, gas_price: 6, gas_limit: 7, to: <<1::160>>, value: 8, v: 27, r: 9, s: 10, data: "hi"}],
+      ...>   header: %Block.Header{number: 5, parent_hash: <<1, 2, 3>>, beneficiary: <<2, 3, 4>>, difficulty: 100, timestamp: 11, mix_hash: <<1>>, nonce: <<2>>}
+      ...> }
+      iex> {:ok, block_1_hash} = Blockchain.Block.put_block(block_1, db)
+      iex> block_2 = %Blockchain.Block{
+      ...>   transactions: [%Blockchain.Transaction{nonce: 5, gas_price: 6, gas_limit: 7, to: <<1::160>>, value: 8, v: 27, r: 9, s: 10, data: "hi"}],
+      ...>   header: %Block.Header{number: 6, parent_hash: block_1_hash, beneficiary: <<2, 3, 4>>, difficulty: 100, timestamp: 11, mix_hash: <<1>>, nonce: <<2>>}
+      ...> }
+      iex> Blockchain.Block.put_block(block_2, db)
+      iex> Blockchain.Block.get_block_hash_by_steps(block_2 |> Blockchain.Block.hash, 0, db)
+      {:ok, <<203, 210, 109, 46, 207, 246, 94, 33, 247, 97, 60, 56, 65, 134,
+              203, 120, 62, 64, 59, 64, 101, 190, 181, 7, 242, 215, 247, 212,
+              107, 12, 92, 9>>}
+      iex> Blockchain.Block.get_block_hash_by_steps(block_2 |> Blockchain.Block.hash, 1, db)
+      {:ok, <<78, 28, 127, 10, 192, 253, 127, 239, 254, 179, 39, 34, 245, 44,
+              152, 98, 128, 71, 238, 155, 100, 161, 199, 71, 243, 223, 172, 191,
+              74, 99, 128, 63>>}
+  """
+  @spec get_block_hash_by_steps(EVM.hash, non_neg_integer(), DB.db) :: {:ok, EVM.hash} | :not_found
+  def get_block_hash_by_steps(curr_block_hash, steps, db) do
+    do_get_block_hash_by_steps(curr_block_hash, steps, db)
+  end
+
+  @spec get_block_hash_by_steps(EVM.hash, non_neg_integer(), DB.db) :: {:ok, EVM.hash} | :not_found
+  defp do_get_block_hash_by_steps(block_hash, 0, _db), do: {:ok, block_hash}
+  defp do_get_block_hash_by_steps(_block_hash, steps, _db) when steps < 0 or steps > 256, do: :not_found
+  defp do_get_block_hash_by_steps(block_hash, steps, db) do
+    with {:ok, block} <- get_block(block_hash, db) do
+      do_get_block_hash_by_steps(block.header.parent_hash, steps - 1, db)
+    end
+  end
+
   @doc """
   Returns the parent node for a given block,
   if it exists.

lib/blockchain/interface/account_interface.ex

@@ -31,6 +31,15 @@ defimpl EVM.Interface.AccountInterface, for: Blockchain.Interface.AccountInterfa
     end
   end
 
+  # TODO: Add test case
+  @spec get_account_code(EVM.Interface.AccountInterface.t, EVM.state, EVM.address) :: nil | binary()
+  def get_account_code(_account_interface, state, address) do
+    case Blockchain.Account.get_machine_code(state, address) do
+      {:ok, machine_code} -> machine_code
+      :not_found -> nil
+    end
+  end
+
   # TODO: Add test case
   @spec increment_account_nonce(EVM.Interface.AccountInterface.t, EVM.state, EVM.address) :: { EVM.state, integer() }
   def increment_account_nonce(_account_interface, state, address) do

lib/blockchain/interface/block_interface.ex

@@ -49,4 +49,13 @@ defimpl EVM.Interface.BlockInterface, for: Blockchain.Interface.BlockInterface d
     end
   end
 
+  # TODO: Add test case
+  @spec get_block_by_number(EVM.Interface.BlockInterface.t, non_neg_integer()) :: Block.Header.t | nil
+  def get_block_by_number(block_interface, steps) do
+    case Blockchain.Block.get_block_hash_by_steps(block_interface.block_header |> Block.Header.hash, steps, block_interface.db) do
+      {:ok, block_header} -> block_header
+      :not_found -> nil
+    end
+  end
+
 end

mix.exs

@@ -47,7 +47,7 @@ defmodule Blockchain.Mixfile do
       {:merkle_patricia_tree, "~> 0.2.5"},
       {:dialyxir, "~> 0.5", only: [:dev], runtime: false},
       {:ex_rlp, "~> 0.2.1"},
-      {:evm, "~> 0.1.8"},
+      {:evm, "~> 0.1.10"},
       {:poison, "~> 3.1.0"},
     ]
   end

mix.lock

@@ -3,7 +3,7 @@
   "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.3", "206eb2e2ac1a794aa5256f3982de7a76bf4579ff91cb28d0e17ea2c9491e46a4", [:mix], [], "hexpm"},
   "eleveldb": {:hex, :eleveldb, "2.2.20", "1fff63a5055bbf4bf821f797ef76065882b193f5e8095f95fcd9287187773b58", [:rebar3], [], "hexpm"},
-  "evm": {:hex, :evm, "0.1.8", "2dd65a5cb388c93153820d51efef21f268d75032f26f66af4720d7a3c9200328", [:mix], [{:keccakf1600, "~> 2.0.0", [hex: :keccakf1600_orig, repo: "hexpm", optional: false]}, {:merkle_patricia_tree, "~> 0.2.5", [hex: :merkle_patricia_tree, repo: "hexpm", optional: false]}], "hexpm"},
+  "evm": {:hex, :evm, "0.1.10", "3bb9355a563005af9233a5af3d5d6b411070ecb3b52c744f0242697179bb9f9d", [:mix], [{:keccakf1600, "~> 2.0.0", [hex: :keccakf1600_orig, repo: "hexpm", optional: false]}, {:merkle_patricia_tree, "~> 0.2.5", [hex: :merkle_patricia_tree, repo: "hexpm", optional: false]}], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.16.2", "3b3e210ebcd85a7c76b4e73f85c5640c011d2a0b2f06dcdf5acdb2ae904e5084", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"},
   "ex_rlp": {:hex, :ex_rlp, "0.2.1", "bd320900d6316cdfe01d365d4bda22eb2f39b359798daeeffd3bd1ca7ba958ec", [:mix], [], "hexpm"},
   "exleveldb": {:hex, :exleveldb, "0.11.1", "37c0414208a50d2419d8246305e6c4a33ed339c25c0bdfa27774795e1e089f7b", [:mix], [{:eleveldb, "~> 2.2.19", [hex: :eleveldb, repo: "hexpm", optional: false]}], "hexpm"},