Add block data support

lib/rex/java/serialization/model.rb

@@ -3,4 +3,5 @@ require 'rex/java/serialization/model/end_block_data'
 require 'rex/java/serialization/model/null_reference'
 require 'rex/java/serialization/model/utf'
 require 'rex/java/serialization/model/long_utf'
+require 'rex/java/serialization/model/block_data'
 require 'rex/java/serialization/model/field'

lib/rex/java/serialization/model/block_data.rb

@@ -0,0 +1,55 @@
+module Rex
+  module Java
+    module Serialization
+      module Model
+        # This class provides a block data representation
+        class BlockData < Element
+
+          # @!attribute length
+          #   @return [Integer] the length of the block
+          attr_accessor :length
+          # @!attribute contents
+          #   @return [String] the contents of the block
+          attr_accessor :contents
+
+          # @param contents [String] the contents of the block
+          def initialize(contents = '')
+            self.contents = contents
+            self.length = contents.length
+          end
+
+          # Unserializes a Java::Serialization::Model::BlockData
+          #
+          # @param io [IO] the io to read from
+          # @return [self] if deserialization is possible
+          # @return [nil] if deserialization isn't possible
+          def decode(io)
+            raw_length = io.read(1)
+            return nil if raw_length.nil?
+            self.length = raw_length.unpack('C')[0]
+
+            if length == 0
+              self.contents = ''
+            else
+              self.contents = io.read(length)
+              return nil if contents.nil? || contents.length != length
+            end
+
+            self
+          end
+
+          # Serializes the Java::Serialization::Model::BlockData
+          #
+          # @return [String] if serialization is possible
+          # @return [nil] if serialization isn't possible
+          def encode
+            encoded = [length].pack('C')
+            encoded << contents
+
+            encoded
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/rex/java/serialization/model/block_data_spec.rb

@@ -0,0 +1,91 @@
+require 'rex/java'
+require 'stringio'
+
+describe Rex::Java::Serialization::Model::BlockData do
+  subject(:block) do
+    described_class.new
+  end
+
+  let(:sample_block) { "\x10\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10" }
+  let(:sample_block_io) { StringIO.new(sample_block) }
+  let(:empty_block) { "\x00" }
+  let(:empty_block_io) { StringIO.new(empty_block) }
+  let(:incomplete_block) { "\x10\x01\x02\x03\x04\x05" }
+  let(:incomplete_block_io) { StringIO.new(incomplete_block) }
+  let(:empty_io) { StringIO.new('') }
+
+  describe ".new" do
+    it "Rex::Java::Serialization::Model::BlockData" do
+      expect(block).to be_a(Rex::Java::Serialization::Model::BlockData)
+    end
+
+    it "initializes length to 0" do
+      expect(block.length).to eq(0)
+    end
+
+    it "initializes contents with empty string" do
+      expect(block.contents).to be_empty
+    end
+  end
+
+  describe "#encode" do
+    context "when empty block" do
+      it { expect(block.encode).to eq(empty_block) }
+    end
+
+    context "when filled block" do
+      it do
+        block.length = 16
+        block.contents = "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10"
+        expect(block.encode).to eq(sample_block)
+      end
+    end
+  end
+
+  describe "#decode" do
+    context "when stream contains empty string" do
+      it "returns nil" do
+        expect(block.decode(empty_io)).to be_nil
+      end
+    end
+
+    context "when stream contains empty block" do
+      it "returns a Rex::Java::Serialization::Model::BlockData" do
+        expect(block.decode(empty_block_io)).to be_a(Rex::Java::Serialization::Model::BlockData)
+      end
+
+      it "sets length to 0" do
+        block.decode(empty_block_io)
+        expect(block.length).to eq(0)
+      end
+
+      it "sets contents to empty string" do
+        block.decode(empty_block_io)
+        expect(block.contents).to be_empty
+      end
+    end
+
+    context "when stream contains incomplete block" do
+      it "returns nil" do
+        expect(block.decode(incomplete_block_io)).to be_nil
+      end
+    end
+
+    context "when stream contains correct block" do
+
+      it "returns a Rex::Java::Serialization::Model::BlockData" do
+        expect(block.decode(sample_block_io)).to be_a(Rex::Java::Serialization::Model::BlockData)
+      end
+
+      it "sets length to 0" do
+        block.decode(sample_block_io)
+        expect(block.length).to eq(16)
+      end
+
+      it "sets contents to sample string" do
+        block.decode(sample_block_io)
+        expect(block.contents).to eq("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10")
+      end
+    end
+  end
+end