# coding: utf-8

"""
	A pure python ping implementation using raw sockets.

	Note that ICMP messages can only be send from processes running as root
	(in Windows, you must run this script as 'Administrator').

	Bugs are naturally mine. I'd be glad to hear about them. There are
	certainly word - size dependencies here.
	
	:homepage: https://github.com/toxinu/Pyping/
	:copyleft: 1989-2011 by the python-ping team, see AUTHORS for more details.
	:license: GNU GPL v2, see LICENSE for more details.
"""


import os
import select
import signal
import socket
import struct
import sys
import time


if sys.platform.startswith("win32"):
	# On Windows, the best timer is time.clock()
	default_timer = time.clock
else:
	# On most other platforms the best timer is time.time()
	default_timer = time.time


# ICMP parameters
ICMP_ECHOREPLY = 0 # Echo reply (per RFC792)
ICMP_ECHO = 8 # Echo request (per RFC792)
ICMP_MAX_RECV = 2048 # Max size of incoming buffer

MAX_SLEEP = 1000


def calculate_checksum(source_string):
	"""
	A port of the functionality of in_cksum() from ping.c
	Ideally this would act on the string as a series of 16-bit ints (host
	packed), but this works.
	Network data is big-endian, hosts are typically little-endian
	"""
	countTo = (int(len(source_string) / 2)) * 2
	sum = 0
	count = 0

	# Handle bytes in pairs (decoding as short ints)
	loByte = 0
	hiByte = 0
	while count < countTo:
		if (sys.byteorder == "little"):
			loByte = source_string[count]
			hiByte = source_string[count + 1]
		else:
			loByte = source_string[count + 1]
			hiByte = source_string[count]
		sum = sum + (ord(hiByte) * 256 + ord(loByte))
		count += 2

	# Handle last byte if applicable (odd-number of bytes)
	# Endianness should be irrelevant in this case
	if countTo < len(source_string): # Check for odd length
		loByte = source_string[len(source_string) - 1]
		sum += ord(loByte)

	sum &= 0xffffffff # Truncate sum to 32 bits (a variance from ping.c, which
					  # uses signed ints, but overflow is unlikely in ping)

	sum = (sum >> 16) + (sum & 0xffff)	# Add high 16 bits to low 16 bits
	sum += (sum >> 16)					# Add carry from above (if any)
	answer = ~sum & 0xffff				# Invert and truncate to 16 bits
	answer = socket.htons(answer)

	return answer


def is_valid_ip4_address(addr):
	parts = addr.split(".")
	if not len(parts) == 4:
		return False
	for part in parts:
		try:
			number = int(part)
		except ValueError:
			return False
		if number > 255 or number < 0:
			return False
	return True

def to_ip(addr):
	if is_valid_ip4_address(addr):
		return addr
	return socket.gethostbyname(addr)

class Response(object):
	def __init__(self):
		self.max_rtt = None
		self.min_rtt = None
		self.avg_rtt = None
		self.packet_lost = None
		self.ret_code = None
		self.output = []

		self.packet_size = None
		self.timeout = None
		self.destination = None
		self.destination_ip = None

class Ping(object):
	def __init__(self, destination, timeout=1000, packet_size=55, own_id=None, quiet_output=True, udp=False, bind=None):
		self.quiet_output = quiet_output
		if quiet_output:
			self.response = Response()
			self.response.destination = destination
			self.response.timeout = timeout
			self.response.packet_size = packet_size

		self.destination = destination
		self.timeout = timeout
		self.packet_size = packet_size
		self.udp = udp
		self.bind = bind

		if own_id is None:
			self.own_id = os.getpid() & 0xFFFF
		else:
			self.own_id = own_id

		try:
			# FIXME: Use destination only for display this line here? see: https://github.com/jedie/python-ping/issues/3
			self.dest_ip = to_ip(self.destination)
			if quiet_output:
				self.response.destination_ip = self.dest_ip
		except socket.gaierror as e:
			self.print_unknown_host(e)
		else:
			self.print_start()

		self.seq_number = 0
		self.send_count = 0
		self.receive_count = 0
		self.min_time = 999999999
		self.max_time = 0.0
		self.total_time = 0.0

	#--------------------------------------------------------------------------

	def print_start(self):
		msg = "\nPYTHON-PING %s (%s): %d data bytes" % (self.destination, self.dest_ip, self.packet_size)
		if self.quiet_output:
			self.response.output.append(msg)
		else:
			print(msg)

	def print_unknown_host(self, e):
		msg = "\nPYTHON-PING: Unknown host: %s (%s)\n" % (self.destination, e.args[1])
		if self.quiet_output:
			self.response.output.append(msg)
			self.response.ret_code = 1
		else:
			print(msg)

		raise Exception, "unknown_host"
		#sys.exit(-1)

	def print_success(self, delay, ip, packet_size, ip_header, icmp_header):
		if ip == self.destination:
			from_info = ip
		else:
			from_info = "%s (%s)" % (self.destination, ip)

	   	msg = "%d bytes from %s: icmp_seq=%d ttl=%d time=%.1f ms" % (packet_size, from_info, icmp_header["seq_number"], ip_header["ttl"], delay)

		if self.quiet_output:
			self.response.output.append(msg)
			self.response.ret_code = 0
		else:
			print(msg)
		#print("IP header: %r" % ip_header)
		#print("ICMP header: %r" % icmp_header)

	def print_failed(self):
		msg = "Request timed out."

		if self.quiet_output:
			self.response.output.append(msg)
			self.response.ret_code = 1
		else:
			print(msg)

	def print_exit(self):
		msg = "\n----%s PYTHON PING Statistics----" % (self.destination)

		if self.quiet_output:
			self.response.output.append(msg)
		else:
			print(msg)

		lost_count = self.send_count - self.receive_count
		#print("%i packets lost" % lost_count)
		lost_rate = float(lost_count) / self.send_count * 100.0

		msg = "%d packets transmitted, %d packets received, %0.1f%% packet loss" % (self.send_count, self.receive_count, lost_rate)
	
		if self.quiet_output:
			self.response.output.append(msg)
			self.response.packet_lost = lost_count
		else:
			print(msg)

		if self.receive_count > 0:
			msg = "round-trip (ms)  min/avg/max = %0.3f/%0.3f/%0.3f" % (self.min_time, self.total_time / self.receive_count, self.max_time)
			if self.quiet_output:
				self.response.min_rtt = '%.3f' % self.min_time
				self.response.avg_rtt = '%.3f' % (self.total_time / self.receive_count)
				self.response.max_rtt = '%.3f' % self.max_time
				self.response.output.append(msg)
			else:
				print(msg)

		if self.quiet_output:
			self.response.output.append('\n')
		else:
			print('')

	#--------------------------------------------------------------------------

	def signal_handler(self, signum, frame):
		"""
		Handle print_exit via signals
		"""
		self.print_exit()
		msg = "\n(Terminated with signal %d)\n" % (signum)

		if self.quiet_output:
			self.response.output.append(msg)
			self.response.ret_code = 0
		else:
			print(msg)

		sys.exit(0)

	def setup_signal_handler(self):
		signal.signal(signal.SIGINT, self.signal_handler)   # Handle Ctrl-C
		if hasattr(signal, "SIGBREAK"):
			# Handle Ctrl-Break e.g. under Windows 
			signal.signal(signal.SIGBREAK, self.signal_handler)

	#--------------------------------------------------------------------------

	def header2dict(self, names, struct_format, data):
		""" unpack the raw received IP and ICMP header informations to a dict """
		unpacked_data = struct.unpack(struct_format, data)
		return dict(zip(names, unpacked_data))

	#--------------------------------------------------------------------------

	def run(self, count=None, deadline=None):
		"""
		send and receive pings in a loop. Stop if count or until deadline.
		"""
		if not self.quiet_output:
			self.setup_signal_handler()

		while True:
			delay = self.do()

			self.seq_number += 1
			if count and self.seq_number >= count:
				break
			if deadline and self.total_time >= deadline:
				break

			if delay == None:
				delay = 0

			# Pause for the remainder of the MAX_SLEEP period (if applicable)
			if (MAX_SLEEP > delay):
				time.sleep((MAX_SLEEP - delay) / 1000.0)

		self.print_exit()
		if self.quiet_output:
			return self.response

	def do(self):
		"""
		Send one ICMP ECHO_REQUEST and receive the response until self.timeout
		"""
		try: # One could use UDP here, but it's obscure
			if self.udp:
				current_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.getprotobyname("icmp"))
			else:
				current_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.getprotobyname("icmp"))

			# Bind the socket to a source address
			if self.bind:
				current_socket.bind((self.bind, 0)) # Port number is irrelevant for ICMP

		except socket.error, (errno, msg):
			if errno == 1:
				# Operation not permitted - Add more information to traceback
				etype, evalue, etb = sys.exc_info()
				evalue = etype(
					"%s - Note that ICMP messages can only be send from processes running as root." % evalue
				)
				raise etype, evalue, etb
			raise # raise the original error

		send_time = self.send_one_ping(current_socket)
		if send_time == None:
			return
		self.send_count += 1

		receive_time, packet_size, ip, ip_header, icmp_header = self.receive_one_ping(current_socket)
		current_socket.close()

		if receive_time:
			self.receive_count += 1
			delay = (receive_time - send_time) * 1000.0
			self.total_time += delay
			if self.min_time > delay:
				self.min_time = delay
			if self.max_time < delay:
				self.max_time = delay

			self.print_success(delay, ip, packet_size, ip_header, icmp_header)
			return delay
		else:
			self.print_failed()

	def send_one_ping(self, current_socket):
		"""
		Send one ICMP ECHO_REQUEST
		"""
		# Header is type (8), code (8), checksum (16), id (16), sequence (16)
		checksum = 0

		# Make a dummy header with a 0 checksum.
		header = struct.pack(
			"!BBHHH", ICMP_ECHO, 0, checksum, self.own_id, self.seq_number
		)

		padBytes = []
		startVal = 0x42
		for i in range(startVal, startVal + (self.packet_size)):
			padBytes += [(i & 0xff)]  # Keep chars in the 0-255 range
		data = bytes(padBytes)

		# Calculate the checksum on the data and the dummy header.
		checksum = calculate_checksum(header + data) # Checksum is in network order

		# Now that we have the right checksum, we put that in. It's just easier
		# to make up a new header than to stuff it into the dummy.
		header = struct.pack(
			"!BBHHH", ICMP_ECHO, 0, checksum, self.own_id, self.seq_number
		)

		packet = header + data

		send_time = default_timer()

		try:
			current_socket.sendto(packet, (self.destination, 1)) # Port number is irrelevant for ICMP
		except socket.error as e:
			self.response.output.append("General failure (%s)" % (e.args[1]))
			current_socket.close()
			return

		return send_time

	def receive_one_ping(self, current_socket):
		"""
		Receive the ping from the socket. timeout = in ms
		"""
		timeout = self.timeout / 1000.0

		while True: # Loop while waiting for packet or timeout
			select_start = default_timer()
			inputready, outputready, exceptready = select.select([current_socket], [], [], timeout)
			select_duration = (default_timer() - select_start)
			if inputready == []: # timeout
				return None, 0, 0, 0, 0


			packet_data, address = current_socket.recvfrom(ICMP_MAX_RECV)

			icmp_header = self.header2dict(
				names=[
					"type", "code", "checksum",
					"packet_id", "seq_number"
				],
				struct_format="!BBHHH",
				data=packet_data[20:28]
			)

			receive_time = default_timer()

			if icmp_header["packet_id"] == self.own_id: # Our packet
				ip_header = self.header2dict(
					names=[
						"version", "type", "length",
						"id", "flags", "ttl", "protocol",
						"checksum", "src_ip", "dest_ip"
					],
					struct_format="!BBHHHBBHII",
					data=packet_data[:20]
				)
				packet_size = len(packet_data) - 28
				ip = socket.inet_ntoa(struct.pack("!I", ip_header["src_ip"]))
				# XXX: Why not ip = address[0] ???
				return receive_time, packet_size, ip, ip_header, icmp_header

			timeout = timeout - select_duration
			if timeout <= 0:
				return None, 0, 0, 0, 0

def ping(hostname, timeout=1000, count=3, packet_size=55, *args, **kwargs):
	p = Ping(hostname, timeout, packet_size, *args, **kwargs)
	return p.run(count)
