Add a method to escape filter strings, and some convenience method for creating some common filter patterns, that are automatically escaped.

lib/net/ldap/filter.rb

@@ -79,6 +79,8 @@ class Net::LDAP::Filter
     # <tt>mail</tt> value containing the substring "anderson":
     #
     #   f = Net::LDAP::Filter.eq("mail", "*anderson*")
+    #
+    # This filter does not perform any escaping
     def eq(attribute, value)
       new(:eq, attribute, value)
     end
@@ -136,10 +138,44 @@ class Net::LDAP::Filter
     # Creates a Filter object indicating that a particular attribute value
     # is either not present or does not match a particular string; see
     # Filter::eq for more information.
+    #
+    # This filter does not perform any escaping
     def ne(attribute, value)
       new(:ne, attribute, value)
     end
 
+    ##
+    # Creates a Filter object indicating that the value of a particular
+    # attribute must match a particular string. The attribute value is
+    # escaped, so the "*" character is interpreted literally.
+    def equals(attribute, value)
+      new(:eq, attribute, escape(value))
+    end
+
+    ##
+    # Creates a Filter object indicating that the value of a particular
+    # attribute must begin with a particular string. The attribute value is
+    # escaped, so the "*" character is interpreted literally.
+    def begins(attribute, value)
+      new(:eq, attribute, escape(value) + "*")
+    end
+
+    ##
+    # Creates a Filter object indicating that the value of a particular
+    # attribute must end with a particular string. The attribute value is
+    # escaped, so the "*" character is interpreted literally.
+    def ends(attribute, value)
+      new(:eq, attribute, "*" + escape(value))
+    end
+
+    ##
+    # Creates a Filter object indicating that the value of a particular
+    # attribute must contain a particular string. The attribute value is
+    # escaped, so the "*" character is interpreted literally.
+    def contains(attribute, value)
+      new(:eq, attribute, "*" + escape(value) + "*")
+    end
+
     ##
     # Creates a Filter object indicating that a particular attribute value
     # is greater than or equal to the specified value.
@@ -207,6 +243,12 @@ class Net::LDAP::Filter
     alias_method :present, :present?
     alias_method :pres, :present?
 
+    ##
+    # Escape a string for use in an LDAP filter
+    def escape(string)
+      string.gsub(/[\*\(\)\\\0]/) {|s| sprintf("\\%02x", s[0]) } 
+    end
+
     ##
     # Converts an LDAP search filter in BER format to an Net::LDAP::Filter
     # object. The incoming BER object most likely came to us by parsing an

test/test_filter.rb

@@ -24,6 +24,13 @@ class TestFilter < Test::Unit::TestCase
     assert_equal("(uid=george *)", Filter.eq("uid", "george *").to_s)
   end
 
+  def test_convenience_filters
+    assert_equal("(uid=\\2a)", Filter.equals("uid", "*").to_s)
+    assert_equal("(uid=\\28*)", Filter.begins("uid", "(").to_s)
+    assert_equal("(uid=*\\29)", Filter.ends("uid", ")").to_s)
+    assert_equal("(uid=*\\5c*)", Filter.contains("uid", "\\").to_s)
+  end
+
 	def test_c2
     assert_equal("(uid=george *)",
                  Filter.from_rfc2254("uid=george *").to_rfc2254)