Added USB Port Detection for Readers

lib/smartcard/pcsc/context.rb

@@ -95,6 +95,37 @@ def readers(groups = [])
       groups_ptr.free
     end
   end
+
+  def usb_port_for_reader(reader)
+    begin
+      card = self.card(reader, :shared, :any)
+      begin
+        attrib = card[FFILib::Consts::SCARD_ATTR_CHANNEL_ID]
+        if attrib
+          ddddcccc = attrib.unpack('I')[0]
+          dddd = ddddcccc >> 16
+          if dddd == 0x0020
+            bus = (ddddcccc & 0xFF00) >> 8
+            device_address = ddddcccc & 0xFF
+            # return bus and device_address
+            return {bus: bus, device_address: device_address}
+          else
+            puts "Not a USB reader"
+          end
+        else
+          puts "Unable to get SCARD_ATTR_CHANNEL_ID"
+        end
+      ensure
+        card.disconnect if card
+      end
+    rescue Smartcard::PCSC::Exception => e
+      if e.message.include?("no_smartcard")
+        nil
+      else
+        raise e
+      end
+    end
+  end
 
   # Queries smart-card readers, blocking until a state change occurs.
   #

lib/smartcard/pcsc/ffi_structs.rb

@@ -33,7 +33,8 @@ class ReaderStateQuery < FFI::Struct
            :current_state, Word,
            :event_state, Word,
            :atr_length, Word,
-           :atr, [:char, Consts::MAX_ATR_SIZE]
+           :atr, [:char, Consts::MAX_ATR_SIZE],
+           :usb_address, :pointer
   end
 
   # Low-level protocol information for APDU transmission and reception.

lib/smartcard/pcsc/reader_state_queries.rb

@@ -5,6 +5,7 @@
 # License:: MIT
 
 require 'set'
+require 'json'
 
 # :nodoc: namespace
 module Smartcard::PCSC
@@ -169,6 +170,19 @@ def reader_name=(new_name)
     self[:reader_name] = FFI::MemoryPointer.from_string new_name
   end
 
+  def usb_address
+    if self[:usb_address].null?
+      nil
+    else
+      JSON.parse(self[:usb_address].read_string, symbolize_names: true) 
+    end
+  end
+
+  def usb_address=(new_usb_address)
+    self[:usb_address].free if self[:usb_address].kind_of? FFI::MemoryPointer
+    self[:usb_address] = FFI::MemoryPointer.from_string(new_usb_address.to_json)
+  end
+
   # Packs an unpacked card state (symbol or set of symbols) into a number.
   #
   # This should not be used by client code.

test/pcsc/context_test.rb

@@ -42,6 +42,23 @@ def _check_readers(readers)
                       'each reader name should be a string'
     end    
   end
+
+  def test_usb_port_for_reader
+    readers = @context.readers
+    readers.each do |reader|
+      usb_port = @context.usb_port_for_reader(reader)
+      if usb_port
+        assert_operator usb_port, :kind_of?, Hash, 'usb_port should be a Hash'
+        assert_includes usb_port, :bus, 'usb_port should include :bus key'  
+        assert_includes usb_port, :device_address, 'usb_port should include :device_address key'
+
+        assert_operator usb_port[:bus], :kind_of?, Integer, ':bus should be an Integer'
+        assert_operator usb_port[:device_address], :kind_of?, Integer, ':device_address should be an Integer'
+      else
+        assert_nil usb_port, 'usb_port should be nil for non-USB reader or no card present'
+      end
+    end
+  end
 
   def test_wait_for_status_change
     readers = @context.readers

test/pcsc/reader_state_queries_test.rb

@@ -4,6 +4,7 @@
 
 require 'rubygems'
 require 'smartcard'
+require 'json'
 
 require 'test/unit'
 
@@ -20,6 +21,8 @@ def setup
     @queries[0].atr = 'grreat success'
     @queries[0].reader_name = 'PC/SC Reader 0'
     @queries[1].reader_name = 'CCID Reader 1'
+    @queries[0].usb_address = { :bus => 1, :device_address => 2 }
+    @queries[1].usb_address = { :bus => 1, :device_address => 4 }
   end
 
   def teardown
@@ -65,6 +68,11 @@ def test_reader_names
     assert_equal 'PC/SC Reader 0', @queries[0].reader_name
     assert_equal 'CCID Reader 1', @queries[1].reader_name
   end
+
+  def test_usb_address
+    assert_equal({ :bus => 1, :device_address => 2 }, @queries[0].usb_address)
+    assert_equal({ :bus => 1, :device_address => 4 }, @queries[1].usb_address)
+  end
 
   def test_ack_changes
     @queries.ack_changes