Feat/chapter12 bloom filter

lib/bitcoin/block.rb

@@ -1,6 +1,6 @@
 require_relative '../bitcoin_data_io'
-require_relative '../encoding_helper'
-require_relative '../hash_helper'
+require_relative '../helpers/encoding_helper'
+require_relative '../helpers/hash_helper'
 
 module Bitcoin
   class Block

lib/bitcoin/bloom_filter.rb

@@ -0,0 +1,43 @@
+require_relative '../helpers/hash_helper'
+require_relative '../helpers/encoding_helper'
+require_relative 'network/messages/generic'
+
+module Bitcoin
+  class BloomFilter
+    include EncodingHelper
+    BIP37_CONSTANT = 0xfba4c795
+
+    def initialize(size, function_count, tweak)
+      @size = size
+      @bit_field = [0] * (size * 8)
+      @function_count = function_count
+      @tweak = tweak
+    end
+
+    attr_reader :bit_field
+
+    def add(item)
+      @function_count.times do |i|
+        seed = i * BIP37_CONSTANT + @tweak
+
+        hash_result = HashHelper.murmur3(item, seed: seed)
+        bit = hash_result % (@size * 8)
+        @bit_field[bit] = 1
+      end
+    end
+
+    def filter_bytes
+      bit_field_to_bytes(@bit_field)
+    end
+
+    def filterload(flag: 1)
+      result = encode_varint(@size)
+      result += filter_bytes
+      result += int_to_little_endian(@function_count, 4)
+      result += int_to_little_endian(@tweak, 4)
+      result += int_to_little_endian(flag, 1)
+
+      Bitcoin::Network::Messages::Generic.new('filterload', result)
+    end
+  end
+end

lib/bitcoin/fetcher/uri_fetcher.rb

@@ -1,6 +1,6 @@
 require_relative './fetcher'
 require_relative '../tx'
-require_relative '../../encoding_helper'
+require_relative '../../helpers/encoding_helper'
 require 'net/http'
 require 'stringio'
 

lib/bitcoin/network/envelope.rb

@@ -1,8 +1,8 @@
 # encoding: ascii-8bit
 
 require_relative '../../bitcoin_data_io'
-require_relative '../../encoding_helper'
-require_relative '../../hash_helper'
+require_relative '../../helpers/encoding_helper'
+require_relative '../../helpers/hash_helper'
 
 module Bitcoin
   module Network

lib/bitcoin/network/messages/base_message.rb

@@ -1,5 +1,5 @@
 # encoding: ascii-8bit
-require_relative '../../../encoding_helper'
+require_relative '../../../helpers/encoding_helper'
 
 module Bitcoin
   module Network

lib/bitcoin/network/messages/generic.rb

@@ -0,0 +1,22 @@
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class Generic < BaseMessage
+        def initialize(command, payload)
+          @command = command
+          @payload = payload
+        end
+
+        def command
+          @command
+        end
+
+        def serialize
+          @payload
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/get_data.rb

@@ -0,0 +1,32 @@
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class GetData < BaseMessage
+        TX_DATA_TYPE = 1
+        BLOCK_DATA_TYPE = 2
+        FILTERED_BLOCK_DATA_TYPE = 3
+        COMPACT_BLOCK_DATA_TYPE = 4
+        COMMAND = "getdata"
+
+        def initialize
+          @data = []
+        end
+
+        def add_data(data_type:, identifier:)
+          @data << [data_type, identifier]
+        end
+
+        def serialize
+          result = encode_varint(@data.length)
+          @data.each do |data_type, identifier|
+            result += int_to_little_endian(data_type, 4)
+            result += identifier.reverse
+          end
+          result
+        end
+      end
+    end
+  end
+end

lib/bitcoin/op.rb

@@ -1,6 +1,6 @@
-require_relative '../hash_helper'
-require_relative '../encoding_helper'
-require_relative '../script_helper'
+require_relative '../helpers/hash_helper'
+require_relative '../helpers/encoding_helper'
+require_relative '../helpers/script_helper'
 require_relative '../ecc/signature'
 require_relative '../ecc/s256_point'
 

lib/bitcoin/script.rb

@@ -1,5 +1,5 @@
 require_relative '../bitcoin_data_io'
-require_relative '../encoding_helper'
+require_relative '../helpers/encoding_helper'
 require_relative './op'
 
 module Bitcoin

lib/bitcoin/tx.rb

@@ -1,6 +1,6 @@
 require_relative '../bitcoin_data_io'
-require_relative '../encoding_helper'
-require_relative '../hash_helper'
+require_relative '../helpers/encoding_helper'
+require_relative '../helpers/hash_helper'
 require_relative './fetcher/uri_fetcher'
 require_relative 'script'
 require 'net/http'

lib/ecc/private_key.rb

@@ -1,7 +1,7 @@
 require_relative 's256_point'
 require_relative 'signature'
 require_relative 'secp256k1_constants'
-require_relative '../encoding_helper'
+require_relative '../helpers/encoding_helper'
 require 'openssl'
 
 module ECC

lib/ecc/s256_point.rb

@@ -1,9 +1,9 @@
 require_relative 's256_field'
 require_relative 'point'
 require_relative 'secp256k1_constants'
-require_relative '../encoding_helper'
-require_relative '../hash_helper'
-require_relative '../address_helper'
+require_relative '../helpers/encoding_helper'
+require_relative '../helpers/hash_helper'
+require_relative '../helpers/address_helper'
 module ECC
   class S256Point < Point
     include EncodingHelper

lib/ecc/signature.rb

@@ -1,4 +1,4 @@
-require_relative '../encoding_helper'
+require_relative '../helpers/encoding_helper'
 module ECC
   class Signature
     include EncodingHelper

lib/address_helper.rb → lib/helpers/address_helper.rb

@@ -1,6 +1,6 @@
 # encoding: ascii-8bit
 
-require 'encoding_helper'
+require_relative 'encoding_helper'
 
 module AddressHelper
   include EncodingHelper

lib/encoding_helper.rb → lib/helpers/encoding_helper.rb

@@ -83,6 +83,29 @@ def encode_varint(integer)
     end
   end
 
+  def bit_field_to_bytes(bit_field)
+    raise EncodingError.new("bit_field's length is not divisible by 8") if bit_field.length % 8 != 0
+
+    result = [0] * (bit_field.length / 8)
+    bit_field.each_with_index do |bit, index|
+      byte_index, bit_index = index.divmod(8)
+      result[byte_index] |= 1 << bit_index unless bit.zero?
+    end
+    result.pack('c*')
+  end
+
+  def bytes_to_bit_field(bytes)
+    bytes = bytes.unpack('C*')
+    bit_field = []
+    bytes.each do |byte|
+      8.times do
+        bit_field << (byte & 1)
+        byte >>= 1
+      end
+    end
+    bit_field
+  end
+
   private
 
   def base58_to_num(base58_string)

lib/helpers/hash_helper.rb

@@ -0,0 +1,68 @@
+require 'digest'
+
+module HashHelper
+  MASK32 = 0xFFFFFFFF
+
+  def self.hash160(string)
+    first_round = Digest::SHA256.digest(string)
+    Digest::RMD160.digest(first_round)
+  end
+
+  def self.hash256(string)
+    first_round = Digest::SHA256.digest(string)
+    Digest::SHA256.digest(first_round)
+  end
+
+  # rubocop:disable Metrics/MethodLength
+  def self.murmur3(string, seed: 0) # rubocop:disable Metrics/AbcSize
+    key_bytes = string.bytes
+    result_hash = seed
+
+    rounded_end = (key_bytes.length & 0xfffffffc)
+    (0...rounded_end).step(4) do |i|
+      aux = block32(key_bytes, i)
+      result_hash ^= scramble32(aux)
+      result_hash = rotl32(result_hash, 13)
+      result_hash = result_hash * 5 + 0xe6546b64
+    end
+
+    val = key_bytes.length & 3
+
+    aux = 0
+    (0...3).reverse_each do |i|
+      aux |= (key_bytes[rounded_end + i] & 0xff) << (8 * i) if val >= (i + 1)
+    end
+
+    result_hash ^= scramble32(aux)
+    finalization_mix(result_hash ^ key_bytes.length)
+  end
+  # rubocop:enable Metrics/MethodLength
+
+  private
+
+  def self.finalization_mix(result_hash)
+    result_hash ^= ((result_hash & MASK32) >> 16)
+    result_hash *= 0x85ebca6b
+    result_hash ^= ((result_hash & MASK32) >> 13)
+    result_hash *= 0xc2b2ae35
+    (result_hash ^ ((result_hash & MASK32) >> 16)) & MASK32
+  end
+
+  def self.block32(key_bytes, index)
+    (1..3).map do |i|
+      key_bytes[index + i] << (8 * i)
+    end.reduce(key_bytes[index], :|)
+  end
+
+  def self.rotl32(item, bits_to_rotate)
+    ((item << bits_to_rotate) | ((item & MASK32) >> (32 - bits_to_rotate))) & MASK32
+  end
+
+  def self.scramble32(aux)
+    aux = (aux * 0xcc9e2d51) & MASK32
+    aux = rotl32(aux, 15)
+    (aux * 0x1b873593) & MASK32
+  end
+
+  private_class_method :finalization_mix, :block32, :rotl32, :scramble32
+end

lib/script_helper.rb → lib/helpers/script_helper.rb

@@ -1,4 +1,8 @@
+require_relative 'encoding_helper'
+
 module ScriptHelper
+  include EncodingHelper
+
   def encode_num(num)
     return '' if num.zero?
 

spec/bitcoin/block_spec.rb

@@ -1,5 +1,5 @@
 require 'bitcoin/block'
-require 'encoding_helper'
+require 'helpers/encoding_helper'
 
 RSpec.describe Bitcoin::Block do
   include EncodingHelper

spec/bitcoin/bloom_filter.rb

@@ -0,0 +1,43 @@
+require_relative '../../lib/bitcoin/bloom_filter'
+require_relative '../../lib/helpers/encoding_helper'
+
+RSpec.describe Bitcoin::BloomFilter do
+  include EncodingHelper
+
+  describe '.new' do
+    it 'initializes the bit_field appropiately' do
+      expect(described_class.new(1, 2, 3).bit_field).to eq [0] * 8
+    end
+  end
+
+  describe '#add' do
+    it 'mutates the bit_field correctly' do
+      expected_bit_field = bytes_to_bit_field(from_hex_to_bytes('0000000a080000000140'))
+      bloom_filter = described_class.new(10, 5, 99)
+      expect { bloom_filter.add('Hello World') }
+        .to((change { bloom_filter.bit_field }.to expected_bit_field))
+    end
+  end
+
+  describe '#filter_bytes' do
+    it 'returns the proper filter bytes' do
+      bloom_filter = described_class.new(10, 5, 99)
+      expect(bloom_filter.filter_bytes).to eq bit_field_to_bytes([0] * 10 * 8)
+      bloom_filter.add('Hello World')
+      expect(bloom_filter.filter_bytes).to eq from_hex_to_bytes('0000000a080000000140')
+      bloom_filter.add('Goodbye!')
+      expect(bloom_filter.filter_bytes).to eq from_hex_to_bytes('4000600a080000010940')
+    end
+  end
+
+  describe '#filterload' do
+    it 'returns the proper generic filterload message' do
+      bloom_filter = described_class.new(10, 5, 99)
+      bloom_filter.add('Hello World')
+      bloom_filter.add('Goodbye!')
+      expect(bloom_filter.filterload.command).to eq 'filterload'
+      expect(bloom_filter.filterload.serialize)
+        .to eq from_hex_to_bytes('0a4000600a080000010940050000006300000001')
+    end
+  end
+end

spec/bitcoin/network/envelope_spec.rb

@@ -1,7 +1,7 @@
 # encoding: ascii-8bit
 
 require 'bitcoin/network/envelope'
-require 'encoding_helper'
+require 'helpers/encoding_helper'
 
 RSpec.describe Bitcoin::Network::Envelope do
   include EncodingHelper