Fix a negotiation bug due to a bad context field

rapid7 · Aug 23, 2021 · 2634473 · 2634473
1 parent 0f884d6
commit 2634473
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/lib/ruby_smb/smb2/negotiate_context.rb b/lib/ruby_smb/smb2/negotiate_context.rb
@@ -69,7 +69,11 @@ class CompressionCapabilities < BinData::Record
     class NetnameNegotiateContextId < BinData::Record
       endian  :little
 
-      stringz16 :net_name, label: 'Net Name'
+      count_bytes_remaining :bytes_remaining
+      default_parameter data_length: nil
+      hide :bytes_remaining
+
+      string16 :net_name, label: 'Net Name', read_length: -> { data_length.nil? ? bytes_remaining : data_length }
     end
 
     # An SMB2 TRANSPORT_CAPABILITIES context struct as defined in
@@ -106,7 +110,7 @@ class NegotiateContext < BinData::Record
         preauth_integrity_capabilities SMB2_PREAUTH_INTEGRITY_CAPABILITIES, label: 'Preauthentication Integrity Capabilities'
         encryption_capabilities        SMB2_ENCRYPTION_CAPABILITIES,        label: 'Encryption Capabilities'
         compression_capabilities       SMB2_COMPRESSION_CAPABILITIES,       label: 'Compression Capabilities'
-        netname_negotiate_context_id   SMB2_NETNAME_NEGOTIATE_CONTEXT_ID,   label: 'Netname Negotiate Context ID'
+        netname_negotiate_context_id   SMB2_NETNAME_NEGOTIATE_CONTEXT_ID,   label: 'Netname Negotiate Context ID', data_length: :data_length
         transport_capabilities         SMB2_TRANSPORT_CAPABILITIES,         label: 'Transport Capabilities'
       end
 

diff --git a/spec/lib/ruby_smb/smb2/negotiate_context_spec.rb b/spec/lib/ruby_smb/smb2/negotiate_context_spec.rb
@@ -162,7 +162,7 @@
   end
 end
 
-RSpec.describe RubySMB::SMB2::NetnameNegotiateContextId  do
+RSpec.describe RubySMB::SMB2::NetnameNegotiateContextId do
   subject(:capability) { described_class.new }
 
   it { is_expected.to respond_to :net_name }
@@ -173,7 +173,7 @@
 
   describe '#net_name' do
     it 'is a unicode string' do
-      expect(capability.net_name).to be_a RubySMB::Field::Stringz16
+      expect(capability.net_name).to be_a RubySMB::Field::String16
     end
   end