Add functions to normalize Winodws & Unix paths

The purpose of these functions is to be able to join file/dir paths
safely without trailing slashes, basically for the same reason as
normalize_uri.  Some modules are really buggy when merging paths,
so instead of letting them do it, it's better to use these functions.

Author: wchen-r7

lib/rex/file.rb

@@ -14,7 +14,53 @@ module Rex
 module FileUtils
 
 	#
-	# This methods cleans the supplied path of directory traversal sequences
+	# This method joins the paths together in Unix format.
+	#
+	def self.normalize_unix_path(*strs)
+		new_str = strs * '/'
+		new_str = new_str.gsub!("//", "/") while new_str.index("//")
+
+		new_str
+	end
+
+	#
+	# This method joins the paths together in Windows format.
+	# All reserved characters will be filtered out, including:
+	#  " * : < > ? \ / |
+	#
+	def self.normalize_win_path(*strs)
+		# Convert to the same format so the parsing is easier
+		s = strs * '\\'
+
+		# Filter out double slashes
+		s = s.gsub(/\\\\/, '\\') while s.index('\\\\')
+
+		# Check the items (fie/dir) individually
+		s = s.split(/\\/)
+
+		# Parse the path prefix
+		prefix = (s[0] || '').gsub(/[\*<>\?\/]/, '')
+		if prefix.empty?
+			prefix = '\\'
+		elsif prefix =~ /^\w:$/ and s.length == 1
+			prefix += '\\'
+		end
+
+		# Delete the original prefix. We want the new one later.
+		s.delete_at(0)
+
+		# Filter out all the reserved characters
+		s.map! {|e| e.gsub(/["\*:<>\?\\\/|]/, '') }
+
+		# Put the modified prefix back
+		s.insert(0, prefix)
+
+		# And then safely join the items
+		s *= '\\'
+	end
+
+	#
+	# This method cleans the supplied path of directory traversal sequences
 	# It must accept path/with/..a/folder../starting/or/ending/in/two/dots
 	# but clean ../something as well as path/with/..\traversal
 	#

spec/lib/rex/file_utils_spec.rb

@@ -0,0 +1,54 @@
+require 'rex/file'
+
+describe Rex::FileUtils do
+	context "Class methods" do
+
+		context ".normalize_win_path" do
+			it "should convert an absolute path as an array into Windows format" do
+				described_class.normalize_win_path('C:\\', 'hello', 'world').should eq("C:\\hello\\world")
+			end
+
+			it "should convert an absolute path as a string into Windows format" do
+				described_class.normalize_win_path('C:\\hello\\world').should eq("C:\\hello\\world")
+			end
+
+			it "should convert a path without reserved characters" do
+				described_class.normalize_win_path('C:\\', 'Windows:').should eq("C:\\Windows")
+				described_class.normalize_win_path('C:\\Windows???\\test').should eq("C:\\Windows\\test")
+			end
+
+			it "should convert a path without double slashes" do
+				described_class.normalize_win_path('C:\\\\\\', 'Windows').should eq("C:\\Windows")
+				described_class.normalize_win_path('C:\\\\\\Hello World\\\\whatever.txt').should eq("C:\\Hello World\\whatever.txt")
+				described_class.normalize_win_path('C:\\\\').should eq("C:\\")
+			end
+
+			it "should parse UNC path format as an array" do
+				described_class.normalize_win_path('\\\\127.0.0.1', 'C$').should eq("\\\\127.0.0.1\\C$")
+				described_class.normalize_win_path('\\\\127.0.0.1\\C$').should eq("\\\\127.0.0.1\\C$")
+			end
+
+			it "should parse a relative path in Windows format" do
+				described_class.normalize_win_path('\\\\127.0.0.1', 'C$').should eq("\\\\127.0.0.1\\C$")
+				described_class.normalize_win_path('\\\\127.0.0.1\\C$').should eq("\\\\127.0.0.1\\C$")
+			end
+		end
+
+		context ".normalize_unix_path" do
+			it "should convert an absolute path as an array into Unix format" do
+				described_class.normalize_unix_path('/etc', '/passwd').should eq("/etc/passwd")
+			end
+
+			it "should convert an absolute path as a string into Windows format" do
+				described_class.normalize_unix_path('/etc/passwd').should eq('/etc/passwd')
+			end
+
+			it "should convert a path without double slashes" do
+				described_class.normalize_unix_path('//etc////passwd').should eq("/etc/passwd")
+				described_class.normalize_unix_path('/etc////', 'passwd').should eq('/etc/passwd')
+			end
+		end
+
+	end
+end
+