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format code
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@ayrat555
ayrat555 committed Apr 11, 2018
1 parent 22c1f4e commit 1823e84
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3 changes: 3 additions & 0 deletions .formatter.exs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
[
inputs: ["mix.exs", "{config,lib,test}/**/*.{ex,exs}"]
]
233 changes: 160 additions & 73 deletions lib/block/header.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -3,56 +3,76 @@ defmodule Block.Header do
This structure codifies the header of a block in the blockchain.
"""

@empty_trie MerklePatriciaTree.Trie.empty_trie_root_hash
@empty_keccak [] |> ExRLP.encode |> :keccakf1600.sha3_256

defstruct [
parent_hash: nil, # Hp P(BH)Hr
ommers_hash: @empty_keccak, # Ho KEC(RLP(L∗H(BU)))
beneficiary: nil, # Hc
state_root: @empty_trie, # Hr TRIE(LS(Π(σ, B)))
transactions_root: @empty_trie, # Ht TRIE({∀i < kBTk, i ∈ P : p(i, LT (BT[i]))})
receipts_root: @empty_trie, # He TRIE({∀i < kBRk, i ∈ P : p(i, LR(BR[i]))})
logs_bloom: <<0::2048>>, # Hb bloom
difficulty: nil, # Hd
number: nil, # Hi
gas_limit: 0, # Hl
gas_used: 0, # Hg
timestamp: nil, # Hs
extra_data: <<>>, # Hx
mix_hash: nil, # Hm
nonce: nil, # Hn
]
@empty_trie MerklePatriciaTree.Trie.empty_trie_root_hash()
@empty_keccak [] |> ExRLP.encode() |> :keccakf1600.sha3_256()

# Hp P(BH)Hr
defstruct parent_hash: nil,
# Ho KEC(RLP(L∗H(BU)))
ommers_hash: @empty_keccak,
# Hc
beneficiary: nil,
# Hr TRIE(LS(Π(σ, B)))
state_root: @empty_trie,
# Ht TRIE({∀i < kBTk, i ∈ P : p(i, LT (BT[i]))})
transactions_root: @empty_trie,
# He TRIE({∀i < kBRk, i ∈ P : p(i, LR(BR[i]))})
receipts_root: @empty_trie,
# Hb bloom
logs_bloom: <<0::2048>>,
# Hd
difficulty: nil,
# Hi
number: nil,
# Hl
gas_limit: 0,
# Hg
gas_used: 0,
# Hs
timestamp: nil,
# Hx
extra_data: <<>>,
# Hm
mix_hash: nil,
# Hn
nonce: nil

# As defined in Eq.(35)
@type t :: %__MODULE__{
parent_hash: EVM.hash,
ommers_hash: EVM.trie_root,
beneficiary: EVM.address,
state_root: EVM.trie_root,
transactions_root: EVM.trie_root,
receipts_root: EVM.trie_root,
logs_bloom: binary(), # TODO
difficulty: integer() | nil,
number: integer() | nil,
gas_limit: EVM.val,
gas_used: EVM.val,
timestamp: EVM.timestamp | nil,
extra_data: binary(),
mix_hash: EVM.hash | nil,
nonce: <<_::64>> | nil, # TODO: 64-bit hash?
}
parent_hash: EVM.hash(),
ommers_hash: EVM.trie_root(),
beneficiary: EVM.address(),
state_root: EVM.trie_root(),
transactions_root: EVM.trie_root(),
receipts_root: EVM.trie_root(),
# TODO
logs_bloom: binary(),
difficulty: integer() | nil,
number: integer() | nil,
gas_limit: EVM.val(),
gas_used: EVM.val(),
timestamp: EVM.timestamp() | nil,
extra_data: binary(),
mix_hash: EVM.hash() | nil,
# TODO: 64-bit hash?
nonce: <<_::64>> | nil
}

# The start of the Homestead block, as defined in Eq.(13) of the Yellow Paper (N_H)
@homestead_block 1_150_000

@initial_difficulty 131_072 # d_0 from Eq.(40)
@minimum_difficulty @initial_difficulty # Mimics d_0 in Eq.(39), but variable on different chains
# d_0 from Eq.(40)
@initial_difficulty 131_072
# Mimics d_0 in Eq.(39), but variable on different chains
@minimum_difficulty @initial_difficulty
@difficulty_bound_divisor 2048
@max_extra_data_bytes 32 # Eq.(58)
# Eq.(58)
@max_extra_data_bytes 32

@gas_limit_bound_divisor 1024 # Constant from Eq.(45) and Eq.(46)
@min_gas_limit 125_000 # Eq.(47)
# Constant from Eq.(45) and Eq.(46)
@gas_limit_bound_divisor 1024
# Eq.(47)
@min_gas_limit 125_000

@doc """
Returns the block that defines the start of Homestead.
Expand All @@ -73,7 +93,7 @@ defmodule Block.Header do
iex> Block.Header.serialize(%Block.Header{parent_hash: <<1::256>>, ommers_hash: <<2::256>>, beneficiary: <<3::160>>, state_root: <<4::256>>, transactions_root: <<5::256>>, receipts_root: <<6::256>>, logs_bloom: <<>>, difficulty: 5, number: 1, gas_limit: 5, gas_used: 3, timestamp: 6, extra_data: "Hi mom", mix_hash: <<7::256>>, nonce: <<8::64>>})
[<<1::256>>, <<2::256>>, <<3::160>>, <<4::256>>, <<5::256>>, <<6::256>>, <<>>, 5, 1, 5, 3, 6, "Hi mom", <<7::256>>, <<8::64>>]
"""
@spec serialize(t) :: ExRLP.t
@spec serialize(t) :: ExRLP.t()
def serialize(h) do
[
h.parent_hash,
Expand All @@ -84,9 +104,9 @@ defmodule Block.Header do
h.receipts_root,
h.logs_bloom,
h.difficulty,
(if h.number == 0, do: <<>>, else: h.number),
if(h.number == 0, do: <<>>, else: h.number),
h.gas_limit,
(if h.number == 0, do: <<>>, else: h.gas_used),
if(h.number == 0, do: <<>>, else: h.gas_used),
h.timestamp,
h.extra_data,
h.mix_hash,
Expand All @@ -104,7 +124,7 @@ defmodule Block.Header do
iex> Block.Header.deserialize([<<1::256>>, <<2::256>>, <<3::160>>, <<4::256>>, <<5::256>>, <<6::256>>, <<>>, <<5>>, <<1>>, <<5>>, <<3>>, <<6>>, "Hi mom", <<7::256>>, <<8::64>>])
%Block.Header{parent_hash: <<1::256>>, ommers_hash: <<2::256>>, beneficiary: <<3::160>>, state_root: <<4::256>>, transactions_root: <<5::256>>, receipts_root: <<6::256>>, logs_bloom: <<>>, difficulty: 5, number: 1, gas_limit: 5, gas_used: 3, timestamp: 6, extra_data: "Hi mom", mix_hash: <<7::256>>, nonce: <<8::64>>}
"""
@spec deserialize(ExRLP.t) :: t
@spec deserialize(ExRLP.t()) :: t
def deserialize(rlp) do
[
parent_hash,
Expand Down Expand Up @@ -139,7 +159,7 @@ defmodule Block.Header do
timestamp: :binary.decode_unsigned(timestamp),
extra_data: extra_data,
mix_hash: mix_hash,
nonce: nonce,
nonce: nonce
}
end

Expand All @@ -158,9 +178,9 @@ defmodule Block.Header do
...> |> Block.Header.hash()
<<218, 225, 46, 241, 196, 160, 136, 96, 109, 216, 73, 167, 92, 174, 91, 228, 85, 112, 234, 129, 99, 200, 158, 61, 223, 166, 165, 132, 187, 24, 142, 193>>
"""
@spec hash(t) :: EVM.hash
@spec hash(t) :: EVM.hash()
def hash(header) do
header |> serialize() |> ExRLP.encode |> :keccakf1600.sha3_256()
header |> serialize() |> ExRLP.encode() |> :keccakf1600.sha3_256()
end

@doc """
Expand Down Expand Up @@ -208,7 +228,8 @@ defmodule Block.Header do
false
"""
@spec is_after_homestead?(t, integer()) :: boolean()
def is_after_homestead?(h, homestead_block \\ @homestead_block), do: not is_before_homestead?(h, homestead_block)
def is_after_homestead?(h, homestead_block \\ @homestead_block),
do: not is_before_homestead?(h, homestead_block)

@doc """
Returns true if the block header is valid. This defines
Expand Down Expand Up @@ -251,17 +272,64 @@ defmodule Block.Header do
# TODO: Add tests for setting gas_limit_bound_divisor
# TODO: Add tests for setting min_gas_limit
"""
@spec is_valid?(t, t | nil, integer(), integer(), integer(), integer(), integer(), integer()) :: :valid | {:invalid, [atom()]}
def is_valid?(header, parent_header, homestead_block \\ @homestead_block, initial_difficulty \\ @initial_difficulty, minimum_difficulty \\ @minimum_difficulty, difficulty_bound_divisor \\ @difficulty_bound_divisor, gas_limit_bound_divisor \\ @gas_limit_bound_divisor, min_gas_limit \\ @min_gas_limit) do
@spec is_valid?(t, t | nil, integer(), integer(), integer(), integer(), integer(), integer()) ::
:valid | {:invalid, [atom()]}
def is_valid?(
header,
parent_header,
homestead_block \\ @homestead_block,
initial_difficulty \\ @initial_difficulty,
minimum_difficulty \\ @minimum_difficulty,
difficulty_bound_divisor \\ @difficulty_bound_divisor,
gas_limit_bound_divisor \\ @gas_limit_bound_divisor,
min_gas_limit \\ @min_gas_limit
) do
parent_gas_limit = if parent_header, do: parent_header.gas_limit, else: nil

errors = [] ++
(if header.difficulty == get_difficulty(header, parent_header, initial_difficulty, minimum_difficulty, difficulty_bound_divisor, homestead_block), do: [], else: [:invalid_difficulty]) ++ # Eq.(51)
(if header.gas_used <= header.gas_limit, do: [], else: [:exceeded_gas_limit]) ++ # Eq.(52)
(if is_gas_limit_valid?(header.gas_limit, parent_gas_limit, gas_limit_bound_divisor, min_gas_limit), do: [], else: [:invalid_gas_limit]) ++ # Eq.(53), Eq.(54) and Eq.(55)
(if is_nil(parent_header) or header.timestamp > parent_header.timestamp, do: [], else: [:child_timestamp_invalid]) ++ # Eq.(56)
(if header.number == 0 or header.number == parent_header.number + 1, do: [], else: [:child_number_invalid]) ++ # Eq.(57)
(if byte_size(header.extra_data) <= @max_extra_data_bytes, do: [], else: [:extra_data_too_large])
# Eq.(51)
# Eq.(52)
# Eq.(53), Eq.(54) and Eq.(55)
# Eq.(56)
# Eq.(57)
errors =
[] ++
if(
header.difficulty ==
get_difficulty(
header,
parent_header,
initial_difficulty,
minimum_difficulty,
difficulty_bound_divisor,
homestead_block
),
do: [],
else: [:invalid_difficulty]
) ++
if(header.gas_used <= header.gas_limit, do: [], else: [:exceeded_gas_limit]) ++
if(
is_gas_limit_valid?(
header.gas_limit,
parent_gas_limit,
gas_limit_bound_divisor,
min_gas_limit
),
do: [],
else: [:invalid_gas_limit]
) ++
if(
is_nil(parent_header) or header.timestamp > parent_header.timestamp,
do: [],
else: [:child_timestamp_invalid]
) ++
if(
header.number == 0 or header.number == parent_header.number + 1,
do: [],
else: [:child_number_invalid]
) ++
if byte_size(header.extra_data) <= @max_extra_data_bytes,
do: [],
else: [:extra_data_too_large]

case errors do
[] -> :valid
Expand All @@ -279,7 +347,7 @@ defmodule Block.Header do
iex> Block.Header.available_gas(%Block.Header{gas_limit: 50_000, gas_used: 30_000})
20_000
"""
@spec available_gas(t) :: EVM.Gas.t
@spec available_gas(t) :: EVM.Gas.t()
def available_gas(header) do
header.gas_limit - header.gas_used
end
Expand Down Expand Up @@ -350,21 +418,35 @@ defmodule Block.Header do
997_888
"""
@spec get_difficulty(t, t | nil, integer()) :: integer()
def get_difficulty(header, parent_header, initial_difficulty \\ @initial_difficulty, minimum_difficulty \\ @minimum_difficulty, difficulty_bound_divisor \\ @difficulty_bound_divisor, homestead_block \\ @homestead_block) do
def get_difficulty(
header,
parent_header,
initial_difficulty \\ @initial_difficulty,
minimum_difficulty \\ @minimum_difficulty,
difficulty_bound_divisor \\ @difficulty_bound_divisor,
homestead_block \\ @homestead_block
) do
cond do
header.number == 0 -> initial_difficulty
header.number == 0 ->
initial_difficulty

is_before_homestead?(header, homestead_block) ->
# Find the delta from parent block
difficulty_delta = difficulty_x(parent_header.difficulty, difficulty_bound_divisor) * difficulty_s1(header, parent_header) + difficulty_e(header)
difficulty_delta =
difficulty_x(parent_header.difficulty, difficulty_bound_divisor) *
difficulty_s1(header, parent_header) + difficulty_e(header)

# Add delta to parent block
next_difficulty = parent_header.difficulty + difficulty_delta

# Return next difficulty, capped at minimum
max(minimum_difficulty, next_difficulty)

true ->
# Find the delta from parent block (note: we use difficulty_s2 since we're after Homestead)
difficulty_delta = difficulty_x(parent_header.difficulty, difficulty_bound_divisor) * difficulty_s2(header, parent_header) + difficulty_e(header)
difficulty_delta =
difficulty_x(parent_header.difficulty, difficulty_bound_divisor) *
difficulty_s2(header, parent_header) + difficulty_e(header)

# Add delta to parent's difficulty
next_difficulty = parent_header.difficulty + difficulty_delta
Expand All @@ -377,27 +459,28 @@ defmodule Block.Header do
# Eq.(42) ς1 - Effectively decides if blocks are being mined too quicky or too slower
@spec difficulty_s1(t, t) :: integer()
defp difficulty_s1(header, parent_header) do
if header.timestamp < ( parent_header.timestamp + 13 ), do: 1, else: -1
if header.timestamp < parent_header.timestamp + 13, do: 1, else: -1
end

# Eq.(43) ς2
@spec difficulty_s2(t, t) :: integer()
defp difficulty_s2(header, parent_header) do
s = MathHelper.floor( ( header.timestamp - parent_header.timestamp ) / 10 )
s = MathHelper.floor((header.timestamp - parent_header.timestamp) / 10)
max(1 - s, -99)
end

# Eq.(41) x - Creates some multiplier for how much we should change difficulty based on previous difficulty
@spec difficulty_x(integer(), integer()) :: integer()
defp difficulty_x(parent_difficulty, difficulty_bound_divisor), do: MathHelper.floor(parent_difficulty / difficulty_bound_divisor)
defp difficulty_x(parent_difficulty, difficulty_bound_divisor),
do: MathHelper.floor(parent_difficulty / difficulty_bound_divisor)

# Eq.(44) ε - Adds a delta to ensure we're increasing difficulty over time
@spec difficulty_e(t) :: integer()
defp difficulty_e(header) do
MathHelper.floor(
:math.pow(
2,
MathHelper.floor( header.number / 100_000 ) - 2
MathHelper.floor(header.number / 100_000) - 2
)
)
end
Expand Down Expand Up @@ -438,8 +521,13 @@ defmodule Block.Header do
iex> Block.Header.is_gas_limit_valid?(1_000, nil, 1024, 500)
true
"""
@spec is_gas_limit_valid?(EVM.Gas.t, EVM.Gas.t | nil) :: boolean()
def is_gas_limit_valid?(gas_limit, parent_gas_limit, gas_limit_bound_divisor \\ @gas_limit_bound_divisor, min_gas_limit \\ @min_gas_limit) do
@spec is_gas_limit_valid?(EVM.Gas.t(), EVM.Gas.t() | nil) :: boolean()
def is_gas_limit_valid?(
gas_limit,
parent_gas_limit,
gas_limit_bound_divisor \\ @gas_limit_bound_divisor,
min_gas_limit \\ @min_gas_limit
) do
if parent_gas_limit == nil do
# It's not entirely clear from the Yellow Paper
# whether a genesis block should have any limits
Expand All @@ -448,9 +536,8 @@ defmodule Block.Header do
else
max_delta = MathHelper.floor(parent_gas_limit / gas_limit_bound_divisor)

( gas_limit < parent_gas_limit + max_delta ) and
( gas_limit > parent_gas_limit - max_delta ) and
gas_limit > min_gas_limit
gas_limit < parent_gas_limit + max_delta and gas_limit > parent_gas_limit - max_delta and
gas_limit > min_gas_limit
end
end
end
end
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