interfaces.py

#! /usr/bin/python

# A class representing the contents of /etc/network/interfaces

from . import constants

from .adapter import *

class interfaces:
	# Read /etc/network/interfaces.
	# Return an array of networkAdapter instances.
	def parseInterfaces(self):
		from .adapter import networkAdapter

		# Open up the interfaces file. Read only.
		interfaces = open(constants.INTERFACES, "r")

		# Initialize a place to store created networkAdapter objects.
		adapters = []

		# Keep a list of adapters that have the auto or allow-hotplug flags set.
		auto_list = []
		hotplug_list = []

		# Store the interface context.
		# This is the index of the adapters collection.
		context = -1

		# Loop through the interfaces file.
		for line in interfaces:
			# Identify the clauses by analyzing the first word of each line.
			# Go to the next line if the current line is a comment.
			if line.startswith('#') == True:
				pass
			else:
				# Parse the iface clause
				if line.startswith('iface'):
					sline = line.split()
					# Update the context when an iface clause is encountered.
					context += 1
					adapters.append(networkAdapter(sline[1]))
					adapters[context].setAddressSource(sline[-1])
					if sline[2] == 'inet':
						adapters[context].setInet(True)
						# Ignore blank lines.
				if line.isspace() == True:
					pass
				else:
					# Parse the detail clauses.
					if line[0].isspace() == True:
						sline = line.split()
						if sline[0] == 'address':
							adapters[context].setAddress(sline[1])
						if sline[0] == 'netmask':
							adapters[context].setNetmask(sline[1])
						if sline[0] == 'gateway':
							adapters[context].setGateway(sline[1])
						if sline[0] == 'broadcast':
							adapters[context].setBroadcast(sline[1])
						if sline[0] == 'network':
							adapters[context].setNetwork(sline[1])
						if sline[0].startswith('bridge') == True:
							opt = sline[0].split('_')
							sline.pop(0)
							ifs = " ".join(sline)
							adapters[context].replaceBropt(opt[1], ifs)
						if sline[0] == 'up' or sline[0] == 'down' or sline[0] == 'pre-up' or sline[0] == 'post-down':
							ud = sline.pop(0)
							cmd = ' '.join(sline)
							if ud == 'up':
								adapters[context].appendUp(cmd)
							if ud == 'down':
								adapters[context].appendDown(cmd)
							if ud == 'pre-up':
								adapters[context].appendPreUp(cmd)
							if ud == 'post-down':
								adapters[context].appendPostDown(cmd)

				# Identify which adapters are flagged with auto and allow-hotplug.
				if line.startswith('auto'):
					sline = line.split()
					for word in sline:
						if word == 'auto':
							pass
						else:
							auto_list.append(word)
				if line.startswith('allow-hotplug'):
					sline = line.split()
					for word in sline:
						if word == 'allow-hotplug':
							pass
						else:
							hotplug_list.append(word)
							# Set the auto and allow-hotplug options for each adapter.
		for entry in auto_list:
			for adapter in adapters:
				if adapter.export()['name'] == entry:
					adapter.setAuto(True)
		for entry in hotplug_list:
			for adapter in adapters:
				if adapter.export()['name'] == entry:
					adapter.setHotplug(True)

		return adapters

	# Insert a networkAdapter before the given index or at the end of the list.
	def addAdapter(self, options, index=None):

		if index != None:
			self.adapters.insert(index, networkAdapter(options))
		else:
			self.adapters.append(networkAdapter(options))

	# Remove the adapter at the given index.
	def removeAdapter(self, index):
		self.adapters.pop(index)

	def writeInterfaces(self):

		# Back up the old interfaces file.
		import subprocess

		subprocess.call(["mv", constants.INTERFACES, constants.BACKUP])

		# Prepare to write the new interfaces file.
		interfaces = open(constants.INTERFACES, "a")

		# Loop through the provided networkAdaprers and write the new file.
		for adapter in self.adapters:
			# Get dict of details about the adapter.
			ifAttributes = adapter.export()

			# Write auto and allow-hotplug clauses if applicable.
			try:
				if adapter.ifAttributes['auto'] == True:
					d = dict(name=ifAttributes['name'])
					interfaces.write(self.AUTO.substitute(d))
			except KeyError:
				pass

			try:
				if ifAttributes['hotplug'] == True:
					d = dict(name=adapter.ifAttributes['name'])
					interfaces.write(self.HOTPLUG.substitute(d))
			except KeyError:
				pass

			# Construct and write the iface declaration.
			# The inet clause needs a little more processing.
			if ifAttributes['inet'] == True:
				inet_val = 'inet'
			else:
				inet_val = ''

			# Write the source clause.
			# Will not error if omitted. Maybe not the best plan.
			try:
				d = dict(name=ifAttributes['name'], inet=inet_val, source=ifAttributes['source'])
				interfaces.write(self.IFACE.substitute(d))
			except KeyError:
				pass

			# Write the addressing information.
			for field in self.addressFields:
				try:
					d = dict(varient=field, value=ifAttributes[field])
					interfaces.write(self.CMD.substitute(d))
				# Keep going if a field isn't provided.
				except KeyError:
					pass

			# Write the bridge information.
			for field in self.bridgeFields:
				try:
					d = dict(varient="bridge_" + field, value=ifAttributes['bridge-opts'][field])
					interfaces.write(self.CMD.substitute(d))
				# Keep going if a field isn't provided.
				except KeyError:
					pass

			# Write the up, down, pre-up, and post-down clauses.
			for field in self.prepFields:
				for item in ifAttributes[field]:
					try:
						d = dict(varient=field, value=item)
						interfaces.write(self.CMD.substitute(d))
					# Keep going if a field isn't provided.
					except KeyError:
						pass

	# Set up the interfaces object.
	def __init__(self):
		self.adapters = self.parseInterfaces()

		# Define templetes for blocks used in /etc/network/interfaces.
		from string import Template

		self.AUTO = Template('auto $name\n')
		self.HOTPLUG = Template('allow-hotplug $name\n')
		self.IFACE = Template('iface $name $inet $source\n')
		self.CMD = Template('\t$varient $value\n')

		self.addressFields = ['address', 'network', 'netmask', 'broadcast', 'gateway']
		self.prepFields = ['pre-up', 'up', 'down', 'post-down']
		self.bridgeFields = ['ports', 'fd', 'hello', 'maxage', 'stp']