Feat/chapter 11 simplified payment verification

.rubocop.yml

@@ -495,6 +495,9 @@ Lint/RaiseException:
 Lint/StructNewOverride:
   Description: Disallow overriding the `Struct` built-in methods via `Struct.new`.
   Enabled: true
+Lint/MissingSuper:
+  Exclude:
+    - 'lib/bitcoin/network/messages/*.rb'
 Rails/Delegate:
   Description: Prefer delegate method for delegations.
   Enabled: false

Gemfile

@@ -4,5 +4,7 @@ source "https://rubygems.org"
 
 # gem "rails"
 
-gem "rspec", "~> 3.11", :groups => [:development, :test]
 gem "pry", :groups => [:development]
+gem 'pry-byebug', :groups => [:development]
+gem "rspec", "~> 3.11", :groups => [:development, :test]
+gem "timecop", "~> 0.9.5", groups: [:development, :test]

Gemfile.lock

@@ -1,12 +1,16 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    byebug (11.1.3)
     coderay (1.1.3)
     diff-lcs (1.5.0)
     method_source (1.0.0)
     pry (0.14.1)
       coderay (~> 1.1)
       method_source (~> 1.0)
+    pry-byebug (3.10.1)
+      byebug (~> 11.0)
+      pry (>= 0.13, < 0.15)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
       rspec-expectations (~> 3.11.0)
@@ -20,15 +24,18 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
+    timecop (0.9.5)
 
 PLATFORMS
   arm64-darwin-21
-  x86_64-linux
   ruby
+  x86_64-linux
 
 DEPENDENCIES
   pry
+  pry-byebug
   rspec (~> 3.11)
+  timecop (~> 0.9.5)
 
 BUNDLED WITH
-   2.3.16
+   2.3.20

lib/bitcoin/block.rb

@@ -1,25 +1,31 @@
 require_relative '../bitcoin_data_io'
 require_relative '../encoding_helper'
 require_relative '../hash_helper'
+require_relative '../merkle_helper'
 
 module Bitcoin
   class Block
     include EncodingHelper
     extend EncodingHelper
 
+    GENESIS_BLOCK = from_hex_to_bytes('0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a29ab5f49ffff001d1dac2b7c')
+    TESTNET_GENESIS_BLOCK = from_hex_to_bytes('0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4adae5494dffff001d1aa4ae18')
+    LOWEST_BITS = from_hex_to_bytes('ffff001d')
+
     MAX_TARGET = 0xffff * 256**(0x1d - 3)
     TWO_WEEKS = 60 * 60 * 24 * 14
 
-    def initialize(version, prev_block, merkle_root, timestamp, bits, nonce)
+    def initialize(version, prev_block, merkle_root, timestamp, bits, nonce, tx_hashes: nil)
       @version = version
       @prev_block = prev_block
       @merkle_root = merkle_root
       @timestamp = timestamp
       @bits = bits
       @nonce = nonce
+      @tx_hashes = tx_hashes
     end
 
-    attr_accessor :version, :prev_block, :merkle_root, :timestamp, :bits, :nonce
+    attr_accessor :version, :prev_block, :merkle_root, :timestamp, :bits, :nonce, :tx_hashes
 
     def self.parse(io)
       io = BitcoinDataIO(io)
@@ -103,5 +109,12 @@ def pow_valid?
       block_header_hash = HashHelper.hash256(serialize)
       little_endian_to_int(block_header_hash) < target
     end
+
+    def merkle_root_valid?
+      hashes = @tx_hashes.map(&:reverse)
+      computed_root = MerkleHelper.merkle_root(hashes)
+
+      computed_root.reverse == @merkle_root
+    end
   end
 end

lib/bitcoin/merkle_block.rb

@@ -0,0 +1,55 @@
+require_relative '../bitcoin_data_io'
+require_relative '../encoding_helper'
+require_relative '../merkle_tree'
+
+module Bitcoin
+  class MerkleBlock
+    include EncodingHelper
+    extend EncodingHelper
+
+    def initialize(version, prev_block, merkle_root, timestamp, bits, nonce,
+      total_tx, tx_hashes, flags)
+
+      @version = version
+      @prev_block = prev_block
+      @merkle_root = merkle_root
+      @timestamp = timestamp
+      @bits = bits
+      @nonce = nonce
+      @total_tx = total_tx
+      @tx_hashes = tx_hashes
+      @flags = flags
+    end
+
+    attr_accessor :version, :prev_block, :merkle_root, :timestamp, :bits, :nonce,
+                  :total_tx, :tx_hashes, :flags
+
+    def self.parse(io)
+      io = BitcoinDataIO(io)
+
+      version = little_endian_to_int(io.read(4))
+      prev_block = io.read_le(32)
+      merkle_root = io.read_le(32)
+      timestamp = little_endian_to_int(io.read(4))
+      bits = io.read(4)
+      nonce = io.read(4)
+      total_tx = little_endian_to_int(io.read(4))
+      num_hashes = io.read_varint
+      tx_hashes = []
+      num_hashes.times { tx_hashes << io.read_le(32) }
+      num_flags = io.read_varint
+      flags = io.read_le(num_flags)
+
+      new(version, prev_block, merkle_root, timestamp, bits, nonce, total_tx, tx_hashes, flags)
+    end
+
+    def valid?
+      flag_bits = bytes_to_bit_field(@flags.reverse)
+      hashes = @tx_hashes.map(&:reverse)
+      tree = MerkleTree.new(@total_tx)
+      tree.populate_tree(flag_bits, hashes)
+
+      tree.root.reverse == @merkle_root
+    end
+  end
+end

lib/bitcoin/network/envelope.rb

@@ -0,0 +1,74 @@
+# encoding: ascii-8bit
+
+require_relative '../../bitcoin_data_io'
+require_relative '../../encoding_helper'
+require_relative '../../hash_helper'
+
+module Bitcoin
+  module Network
+    class Envelope
+      include EncodingHelper
+      extend EncodingHelper
+
+      NETWORK_MAGIC = "f9beb4d9"
+      TESTNET_NETWORK_MAGIC = "0b110907"
+
+      def initialize(command, payload, testnet=false)
+        @command_bytes = command
+        @payload_bytes = payload
+        @magic_hex = testnet ? TESTNET_NETWORK_MAGIC : NETWORK_MAGIC
+      end
+
+      attr_accessor :command_bytes, :payload_bytes, :magic_hex
+
+      def self.parse(io)
+        bitcoin_io = BitcoinDataIO(io)
+        network_magic_bytes = bitcoin_io.read(4)
+        raise IOError.new('no data received') if network_magic_bytes.nil?
+
+        network_magic = bytes_to_hex(network_magic_bytes)
+        raise IOError.new('unrecognized network magic') unless [
+          NETWORK_MAGIC, TESTNET_NETWORK_MAGIC
+        ].include? network_magic
+
+        command = bitcoin_io.read(12).delete("\x00")
+        payload_length = bitcoin_io.read_le_int32
+        checksum = bitcoin_io.read(4)
+        payload = bitcoin_io.read(payload_length) || ''
+
+        raise IOError.new("checksum doesn't match") unless checksum_match?(payload, checksum)
+
+        new(command, payload, network_magic == TESTNET_NETWORK_MAGIC)
+      end
+
+      def self.checksum(payload)
+        HashHelper.hash256(payload).slice(0, 4)
+      end
+
+      def self.checksum_match?(payload, _checksum)
+        checksum(payload) == _checksum
+      end
+
+      def to_s
+        "#{@command_bytes}: #{@payload_bytes}"
+      end
+
+      def serialize
+        result = from_hex_to_bytes(@magic_hex)
+        result << @command_bytes
+        result << "\x00" * (12 - @command_bytes.length)
+        result << int_to_little_endian(@payload_bytes.length, 4)
+        result << self.class.checksum(@payload_bytes)
+        result << @payload_bytes
+
+        result
+      end
+
+      def stream
+        StringIO.new(@payload_bytes)
+      end
+
+      private_class_method :checksum_match?
+    end
+  end
+end

lib/bitcoin/network/messages/base_message.rb

@@ -0,0 +1,16 @@
+# encoding: ascii-8bit
+require_relative '../../../encoding_helper'
+
+module Bitcoin
+  module Network
+    module Messages
+      class BaseMessage
+        include EncodingHelper
+
+        def command
+          self.class::COMMAND
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/get_headers.rb

@@ -0,0 +1,31 @@
+# encoding: ascii-8bit
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class GetHeaders < BaseMessage
+        COMMAND = "getheaders"
+
+        def initialize(version: 70015, num_hashes: 1, start_block: nil, end_block: nil)
+          @version = version
+          @num_hashes = num_hashes
+
+          raise 'a start block is required' if start_block.nil?
+
+          @start_block = start_block
+          @end_block = end_block.nil? ? "\x00" * 32 : end_block
+        end
+
+        def serialize
+          result = int_to_little_endian(@version, 4)
+          result << encode_varint(@num_hashes)
+          result << @start_block.reverse
+          result << @end_block.reverse
+
+          result
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/headers.rb

@@ -0,0 +1,35 @@
+# encoding: ascii-8bit
+require_relative '../../../bitcoin_data_io'
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class Headers < BaseMessage
+        COMMAND = "headers"
+
+        def initialize(blocks:)
+          @blocks = blocks
+        end
+
+        attr_accessor :blocks
+
+        def self.parse(_io)
+          io = BitcoinDataIO(_io)
+
+          num_headers = io.read_varint
+          blocks = []
+
+          num_headers.times do
+            blocks << Bitcoin::Block.parse(io)
+            num_txs = io.read_varint
+
+            raise RuntimeError('number of txs not 0') unless num_txs.zero?
+          end
+
+          new(blocks: blocks)
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/ping.rb

@@ -0,0 +1,25 @@
+# encoding: ascii-8bit
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class Ping < BaseMessage
+        COMMAND = "ping"
+
+        def initialize(nonce)
+          @nonce = nonce
+        end
+
+        def serialize
+          @nonce
+        end
+
+        def self.parse(stream)
+          nonce = stream.read(8)
+          new(nonce)
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/pong.rb

@@ -0,0 +1,25 @@
+# encoding: ascii-8bit
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class Pong < BaseMessage
+        COMMAND = "pong"
+
+        def initialize(nonce)
+          @nonce = nonce
+        end
+
+        def serialize
+          @nonce
+        end
+
+        def self.parse(stream)
+          nonce = stream.read(8)
+          new(nonce)
+        end
+      end
+    end
+  end
+end

lib/bitcoin/network/messages/verack.rb

@@ -0,0 +1,20 @@
+# encoding: ascii-8bit
+require_relative './base_message'
+
+module Bitcoin
+  module Network
+    module Messages
+      class Verack < BaseMessage
+        COMMAND = "verack"
+
+        def serialize
+          ''
+        end
+
+        def self.parse(_)
+          new
+        end
+      end
+    end
+  end
+end