#!/usr/bin/env python
'''
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.
:)
'''

import CryptoBoxLogger
import CryptoBoxContainer
import configobj			# to read and write the config file
import re
import os
import sys
import types


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


class CryptoBoxProps:
	'''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, conf_file=None):
		'''read config and fill class variables'''
		if os.geteuid() != 0:
			sys.stderr.write("You need to be root to run this program!\n")
			sys.exit(1)
		if conf_file == None:
			for f in CONF_LOCATIONS:
				if os.path.exists(os.path.expanduser(f)):
					conf_file = os.path.expanduser(f)
					break
			else:
				sys.stderr.write("Could not find a configuration file. I give up.\n")
				sys.exit(1)
		try:
			self.cbxPrefs = configobj.ConfigObj(conf_file)
		except SyntaxError:
			sys.stderr.write("Error during parsing of configuration file (%s).\n" % (conf_file, ))
			sys.exit(1)
		try:
			nameDB_file = os.path.join(
				self.cbxPrefs["Main"]["DataDir"],
				self.cbxPrefs["Main"]["NameDatabase"])
			if os.path.exists(nameDB_file):
				self.nameDB = configobj.ConfigObj(nameDB_file, create_empty=True)
			else:
				self.nameDB = configobj.ConfigObj(nameDB_file)
		except SyntaxError:
			sys.stderr.write("Error during parsing of name database file (%s).\n" % (nameDB_file, ))
			sys.exit(1)
		self.__cboxUID = int(self.cbxPrefs["System"]["User"])
		self.debug = CryptoBoxLogger.CryptoBoxLogger(
			self.cbxPrefs["Log"]["Level"],
			self.cbxPrefs["Log"]["Facility"], 
			self.cbxPrefs["Log"]["Destination"],
			self.__cboxUID)
		self.dropPrivileges()
		self.debugMessage = self.debug.printMessage
		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"
		"TODO: broken!"
		allowed = self.cbxPrefs["Main"]["AllowedDevices"]
		if type(allowed) == types.StringType: allowed = [allowed]
		for a_dev in allowed:
			if a_dev and re.search('^' + a_dev, devicename):	return True
		return False


	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.logger.debugMessage(
						"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


	def dropPrivileges(self):
		"change the effective uid to 'User' specified in section 'System'"
		if os.getuid() != os.geteuid():
			raise "PrivilegeManager", "we already dropped privileges"
		os.seteuid(self.__cboxUID)
	

	def risePrivileges(self):
		"regain superuser privileges temporarily - call dropPrivileges afterwards!"
		if os.getuid() == os.geteuid():
			raise "PrivilegeManager", "we already have superuser privileges"
		os.seteuid(os.getuid())
		

	""" ************ 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.debugMessage("Could not read /proc/partitions", "warn")
			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 []