#!/usr/bin/env python2.4
'''
This is the web interface for a fileserver managing encrypted filesystems.
 
It was originally written in bash/perl. Now a complete rewrite is in
progress. So things might be confusing here. Hopefully not for long.
:)
'''

# check python version
import sys
(ver_major, ver_minor, ver_sub, ver_desc, ver_subsub) = sys.version_info
if (ver_major < 2) or ((ver_major == 2) and (ver_minor < 4)):
	sys.stderr.write("You need a python version >= 2.4\nCurrent version is:\n %s\n" % sys.version)
	sys.exit(1)

import CryptoBoxContainer
import types
import re
import os
import unittest
import logging
import subprocess
from CryptoBoxExceptions import *

CONF_LOCATIONS = [
	"./cryptobox.conf",
	"~/.cryptobox.conf",
	"/etc/cryptobox/cryptobox.conf"]


class CryptoBox:
	'''this class rules them all!

	put things like logging, conf and oter stuff in here,
	that might be used by more classes, it will be passed on to them'''
	def __init__(self, config_file=None):
		self.__initLogging()
		self.__initPreferences(config_file)
		self.__runTests()


	def __initLogging(self):	
		import logging
		'''initialises the logging system
		
		use it with: 'self.log.[debug|info|warning|error|critical](logmessage)'
		all classes should get the logging instance during __init__:
			self.log = logging.getLogger("CryptoBox")

		first we output all warnings/errors to stderr
		as soon as we opened the config file successfully, we redirect debug output
		to the configured destination'''
		## basicConfig(...) needs python >= 2.4
		try:
			self.log = logging.getLogger("CryptoBox")
			logging.basicConfig(
				format='%(asctime)s %(module)s %(levelname)s %(message)s',
				stderr=sys.stderr)
			self.log.setLevel(logging.ERROR)
			self.log.info("loggingsystem is up'n running")
			## from now on everything can be logged via self.log...
		except:
			raise CBEnvironmentError("couldn't initialise the loggingsystem. I give up.")


	def __initPreferences(self, config_file):
		try:
			import configobj	## needed for reading and writing of the config file
		except:
			raise CBEnvironmentError("couldn't import 'configobj'! Try 'apt-get install python-configobj'.")
		# search for the configuration file
		if config_file is None:
			# no config file was specified - we will look for it in the ususal locations
			conf_file_list = [os.path.expanduser(f)
				for f in CONF_LOCATIONS
				if os.path.exists(os.path.expanduser(f))]
			if not conf_file_list:
				# no possible config file found in the usual locations
				raise CBConfigUnavailableError()
			config_file = conf_file_list[0]
		else:
			# a config file was specified (e.g. via command line)
			if type(config_file) != types.StringType:
				raise CBConfigUnavailableError("invalid config file specified: %s" % config_file)
			if not os.path.exists(config_file):
				raise CBConfigUnavailableError("could not find the specified configuration file (%s)" % config_file)
		try:
			self.cbxPrefs = configobj.ConfigObj(config_file)
			if self.cbxPrefs:
				self.log.info("found config: %s" % self.cbxPrefs.items())
			else: 
				raise CBConfigUnavailableError("failed to load the config file: %s" % config_file)
		except IOError:
			raise CBConfigUnavailableError("unable to open the config file: %s" % config_file)
		try:
			try:
				nameDB_file = self.cbxPrefs["Locations"]["NameDatabase"]
			except KeyError:
				raise CBConfigUndefinedError("Locations", "NameDatabase")
		except SyntaxError:
			raise CBConfigInvalidValueError("Locations", "NameDatabase", nameDB_file, "failed to interprete the filename of the name database correctly")
		## create nameDB is necessary
		if os.path.exists(nameDB_file):
			self.nameDB = configobj.ConfigObj(nameDB_file)
		else:
			self.nameDB = configobj.ConfigObj(nameDB_file, create_empty=True)
		## check if nameDB file was created successfully?
		if not os.path.exists(nameDB_file):
			raise CBEnvironmentError("failed to create name database (%s)" % nameDB_file)
		# get the loglevel
		try:
			log_level = self.cbxPrefs["Log"]["Level"].upper()
			log_level_avail = ["DEBUG", "INFO", "WARN", "ERROR"]
			if not log_level in log_level_avail:
				raise TypeError
		except KeyError:
			raise CBConfigUndefinedError("Log", "Level")
		except TypeError:
			raise CBConfigInvalidValueError("Log", "Level", log_level, "invalid log level: only %s are allowed" % log_level_avail)
		try:
			try:
				new_handler = logging.FileHandler(self.cbxPrefs["Log"]["Details"])
			except KeyError:
				raise CBConfigUndefinedError("Log", "Details")
		except IOError:
			raise CBEnvironmentError("could not create the log file (%s)" % self.cbxPrefs["Log"]["Details"])
		new_handler.setFormatter(logging.Formatter('%(asctime)s %(module)s %(levelname)s: %(message)s'))
		self.log.addHandler(new_handler)
		## do not call parent's handlers
		self.log.propagate = False
		## 'log_level' is a string -> use 'getattr'
		self.log.setLevel(getattr(logging,log_level))


	# do some initial checks
	def __runTests(self):
		self.__runTestRootPriv()
		self.__runTestLocations()


	def __runTestLocations(self):
		"""check if all configured locations exist"""
		try:
			conf_locations = self.cbxPrefs["Locations"]
		except KeyError:
			raise CBConfigUndefinedError("Locations")
		try:
			for key in ["MountParentDir", "NameDatabase", "TemplateDir", "LangDir", "DocDir"]:
				value = self.cbxPrefs["Locations"][key]
				#if not (os.path.exists(value) and os.access(value, os.R_OK)):
				if not os.access(value, os.R_OK):
					raise CBConfigInvalidValueError("Locations", key, value, "could not access")
		except KeyError:
			raise CBConfigUndefinedError("Locations", key)

	def __runTestRootPriv(self):
		"""try to run 'super' with 'CryptoBoxRootActions'"""
		try:
			devnull = open(os.devnull, "w")
		except IOError:
			raise CBEnvironmentError("could not open %s for writing!" % os.devnull)
		try:
			prog_super = self.cbxPrefs["Programs"]["super"]
		except KeyError:
			raise CBConfigUndefinedError("Programs", "super")
		try:
			prog_rootactions = self.cbxPrefs["Programs"]["CryptoBoxRootActions"]
		except KeyError:
			raise CBConfigUndefinedError("Programs", "CryptoBoxRootActions")
		try:
			proc = subprocess.Popen(
				shell = False,
				stdout = devnull,
				stderr = devnull,
				args = [prog_super, prog_rootactions, "check"])
		except OSError:
			raise CBEnvironmentError("failed to execute 'super' (%s)" % self.cbxPrefs["Programs"]["super"])
		proc.wait()
		if proc.returncode != 0:
			raise CBEnvironmentError("failed to call CryptoBoxRootActions (%s) via 'super' - maybe you did not add the appropriate line to /etc/super.tab?" % prog_rootactions)


	# this method just demonstrates inheritance effects - may be removed
	def cbx_inheritance_test(self, string="you lucky widow"):
		self.log.info(string)
	


# RFC: why should CryptoBoxProps inherit CryptoBox? [l]
# RFC: shouldn't we move all useful functions of CryptoBoxProps to CryptoBox? [l]
class CryptoBoxProps(CryptoBox):
	'''Get and set the properties of a CryptoBox

	This class contains all available devices that may be accessed.
	All properties of the cryptobox can be accessed by this class.
	'''

	def __init__(self, config_file=None):
		'''read config and fill class variables'''
		CryptoBox.__init__(self, config_file)

		#self.cbx_inheritance_test()
		#print self.cbxPrefs.items()
		####

		self.containers = []
		for device in self.__getAvailablePartitions():
			if self.isDeviceAllowed(device):
				self.containers.append(CryptoBoxContainer.CryptoBoxContainer(device, self))


	def isDeviceAllowed(self, devicename):
		"check if a device is white-listed for being used as cryptobox containers"
		allowed = self.cbxPrefs["Main"]["AllowedDevices"]
		if type(allowed) == types.StringType: allowed = [allowed]
		for a_dev in allowed:
			"remove double dots and so on ..."
			real_device = os.path.realpath(devicename)
			if a_dev and re.search('^' + a_dev, real_device):	return True
		return False


	def getLogData(self, lines=None, maxSize=None):
		"""get the most recent log entries of the cryptobox

		the maximum number and size of these entries can be limited by 'lines' and 'maxSize'
		"""
		# return nothing if the currently selected log output is not a file
		try:
			if self.cbxPrefs["Log"]["Destination"].upper() != "FILE": return []
			log_file = self.cbxPrefs["Log"]["Details"]
		except KeyError:
			self.log.error("could not evaluate one of the following config settings: [Log]->Destination or [Log]->Details")
			return []
		try:
			fd = open(log_file, "r")
			if maxSize:	content = fd.readlines(maxSize)
			else:	content = fd.readlines()
			fd.close()
		except IOError:
			self.log.warn("failed to read the log file (%s)" % log_file)
			return []
		if lines:	content = content[-lines:]
		return content


	def getContainerList(self, filterType=None, filterName=None):
		"retrieve the list of all containers of this cryptobox"
		try:
			result = self.containers[:]
			if filterType != None:
				if filterType in range(len(CryptoBoxContainer.Types)):
					return [e for e in self.containers if e.getType() == filterType]
				else:
					self.log.info("invalid filterType (%d)" % filterType)
					result.clear()
			if filterName != None:
				result = [e for e in self.containers if e.getName() == filterName]
			return result
		except AttributeError:
			return []


	def setNameForUUID(self, uuid, name):
		"assign a name to a uuid in the ContainerNameDatabase"
		used_uuid = self.getUUIDForName(name)
		"first remove potential conflicting uuid/name combination"
		if used_uuid: del self.nameDB[used_uuid]
		self.nameDB[uuid] = name
		self.nameDB.write()


	def getNameForUUID(self, uuid):
		"get the name belonging to a specified key (usually the UUID of a fs)"
		try:
			return self.nameDB[uuid]
		except KeyError:
			return None
	

	def getUUIDForName(self, name):
		"""	get the key belonging to a value in the ContainerNameDatabase
			this is the reverse action of 'getNameForUUID'	"""
		for key in self.nameDB.keys():
			if self.nameDB[key] == name: return key
		"the uuid was not found"
		return None


	""" ************ internal stuff starts here *********** """

	def __getAvailablePartitions(self):
		"retrieve a list of all available containers"
		ret_list = []
		try:
			"the following reads all lines of /proc/partitions and adds the mentioned devices"
			fpart = open("/proc/partitions", "r")
			try:
				line = fpart.readline()
				while line:
					p_details = line.split()
					if (len(p_details) == 4):
						"the following code prevents double entries like /dev/hda and /dev/hda1"
						(p_major, p_minor, p_size, p_device) = p_details
						if  re.search('^[0-9]*$', p_major) and re.search('^[0-9]*$', p_minor):
							p_parent = re.sub('[1-9]?[0-9]$', '', p_device)
							if p_parent == p_device:
								if [e for e in ret_list if re.search('^' + p_parent + '[1-9]?[0-9]$', e)]:
									"major partition - its children are already in the list"
									pass
								else:
									"major partition - but there are no children for now"
									ret_list.append(p_device)
							else:
								"minor partition - remove parent if necessary"
								if p_parent in ret_list: ret_list.remove(p_parent)
								ret_list.append(p_device)
					line = fpart.readline()
			finally:
				fpart.close()
			return [self.__getAbsoluteDeviceName(e) for e in ret_list]
		except IOError:
			self.log.warning("Could not read /proc/partitions")
			return []


	def __getAbsoluteDeviceName(self, shortname):
		"""	returns the absolute file name of a device (e.g.: "hda1" -> "/dev/hda1")
			this does also work for device mapper devices
			if the result is non-unique, one arbitrary value is returned"""
		if re.search('^/', shortname): return shortname
		default = os.path.join("/dev", shortname)
		if os.path.exists(default): return default
		result = self.__findMajorMinorOfDevice(shortname)
		"if no valid major/minor was found -> exit"
		if not result: return default
		(major, minor) = result
		"for device-mapper devices (major == 254) ..."
		if major == 254:
			result = self.__findMajorMinorDeviceName("/dev/mapper", major, minor)
			if result: return result[0]
		"now check all files in /dev"
		result = self.__findMajorMinorDeviceName("/dev", major, minor)
		if result: return result[0]
		return default


	def __findMajorMinorOfDevice(self, device):
		"return the major/minor numbers of a block device by querying /sys/block/?/dev"
		if not os.path.exists(os.path.join("/sys/block", device)): return None
		blockdev_info_file = os.path.join(os.path.join("/sys/block", device), "dev")
		try:
			f_blockdev_info = open(blockdev_info_file, "r")
			blockdev_info = f_blockdev_info.read()
			f_blockdev_info.close()
			(str_major, str_minor) = blockdev_info.split(":")
			"numeric conversion"
			try:
				major = int(str_major)
				minor = int(str_minor)
				return (major, minor)
			except ValueError:
				"unknown device numbers -> stop guessing"
				return None
		except IOError:
			pass


	def __findMajorMinorDeviceName(self, dir, major, minor):
		"returns the names of devices with the specified major and minor number"
		collected = []
		try:
			subdirs = [os.path.join(dir, e) for e in os.listdir(dir) if (not os.path.islink(os.path.join(dir, e))) and os.path.isdir(os.path.join(dir, e))]
			"do a recursive call to parse the directory tree"
			for dirs in subdirs:
				collected.extend(self.__findMajorMinorDeviceName(dirs, major, minor))
			"filter all device inodes in this directory"
			collected.extend([os.path.realpath(os.path.join(dir, e)) for e in os.listdir(dir) if (os.major(os.stat(os.path.join(dir, e)).st_rdev) == major) and (os.minor(os.stat(os.path.join(dir, e)).st_rdev) == minor)])
			result = []
			for e in collected:
				if e not in result: result.append(e)
			return collected
		except OSError:
			return []


if __name__ == "__main__":
	cb = CryptoBox()