add SMBHeader struct

adds the basic Header for all SMB1 packets

MSP-12907

lib/ruby_smb/smb1/packet.rb

@@ -4,6 +4,7 @@ module Smb1
     # This module holds the namespace for all SMB1 packets and related structures.
     module Packet
       autoload :SmbParameterBlock, 'ruby_smb/smb1/packet/smb_parameter_block'
+      autoload :SmbHeader, 'ruby_smb/smb1/packet/smb_header'
     end
   end
 end

lib/ruby_smb/smb1/packet/smb_header.rb

@@ -0,0 +1,24 @@
+module RubySMB
+  module Smb1
+    module Packet
+
+      # This class represents the Header of an SMB1 Packet.
+      # [2.2.3.1 SMB Header Extensions](https://msdn.microsoft.com/en-us/library/cc246254.aspx)
+      class SmbHeader < BitStruct
+        unsigned :protocol,          32
+        unsigned :command,            8
+        unsigned :nt_status,         32
+        unsigned :flags,              8
+        unsigned :flags2,            16
+        unsigned :pid_high,          16
+        unsigned :security_features, 64
+        unsigned :reserved,          16
+        unsigned :tid,               16
+        unsigned :pid_low,           16
+        unsigned :uid,               16
+        unsigned :mid,               16
+
+      end
+    end
+  end
+end

spec/lib/ruby_smb/smb1/packet/smb_header_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+RSpec.describe RubySMB::Smb1::Packet::SmbHeader do
+
+  subject(:header) { described_class.new }
+
+  it { is_expected.to respond_to :protocol }
+  it { is_expected.to respond_to :command }
+  it { is_expected.to respond_to :nt_status }
+  it { is_expected.to respond_to :flags }
+  it { is_expected.to respond_to :flags2 }
+  it { is_expected.to respond_to :pid_high }
+  it { is_expected.to respond_to :security_features }
+  it { is_expected.to respond_to :reserved }
+  it { is_expected.to respond_to :tid }
+  it { is_expected.to respond_to :pid_low }
+  it { is_expected.to respond_to :uid }
+  it { is_expected.to respond_to :mid }
+end