#! /usr/local/bin/python
# -*- Mode: Python; tab-width: 4 -*-
#
#	Author: Sam Rushing <rushing@nightmare.com>
#	Copyright 1996-2000 by Sam Rushing
#						 All Rights Reserved.
#

RCS_ID =  '$Id: http_server.py,v 1.3 2001/09/02 02:40:30 adamf Exp $'

# python modules
import os
import re
import socket
import stat
import string
import sys
import time

# async modules
import asyncore
import asynchat

# medusa modules
import http_date
import producers
import status_handler
import logger

VERSION_STRING = string.split(RCS_ID)[2]

from counter import counter
from urllib import unquote

# ===========================================================================
#							Request Object
# ===========================================================================

class http_request:

	# default reply code
	reply_code = 200

	request_counter = counter()

	# Whether to automatically use chunked encoding when
	# 
	#   HTTP version is 1.1
	#   Content-Length is not set
	#   Chunked encoding is not already in effect
	#
	# If your clients are having trouble, you might want to disable this.
	use_chunked = 1
	
	# by default, this request object ignores user data.
	collector = None

	def __init__ (self, *args):
		# unpack information about the request
		(self.channel, self.request,
		 self.command, self.uri, self.version,
		 self.header) = args

		self.outgoing = fifo()
		self.reply_headers = {
			'Server'	: 'Medusa/%s' % VERSION_STRING,
			'Date'		: http_date.build_http_date (time.time())
			}
		self.request_number = http_request.request_counter.increment()
		self._split_uri = None
		self._header_cache = {}

	# --------------------------------------------------
	# reply header management
	# --------------------------------------------------
	def __setitem__ (self, key, value):
		self.reply_headers[key] = value

	def __getitem__ (self, key):
		return self.reply_headers[key]

	def has_key (self, key):
		return self.reply_headers.has_key (key)

	def build_reply_header (self):
		return string.join (
			[self.response(self.reply_code)] + map (
				lambda x: '%s: %s' % x,
				self.reply_headers.items()
				),
			'\r\n'
			) + '\r\n\r\n'

	# --------------------------------------------------
	# split a uri
	# --------------------------------------------------

	# <path>;<params>?<query>#<fragment>
	path_regex = re.compile (
	#      path      params    query   fragment
		r'([^;?#]*)(;[^?#]*)?(\?[^#]*)?(#.*)?'
		)

	def split_uri (self):
		if self._split_uri is None:
			m = self.path_regex.match (self.uri)
			if m.end() != len(self.uri):
				raise ValueError, "Broken URI"
			else:
				self._split_uri = m.groups()
		return self._split_uri

	def get_header_with_regex (self, head_reg, group):
		for line in self.header:
			m = head_reg.match (line)
			if m.end() == len(line):
				return head_reg.group (group)
		return ''

	def get_header (self, header):
		header = string.lower (header)
		hc = self._header_cache
		if not hc.has_key (header):
			h = header + ': '
			hl = len(h)
			for line in self.header:
				if string.lower (line[:hl]) == h:
					r = line[hl:]
					hc[header] = r
					return r
			hc[header] = None
			return None
		else:
			return hc[header]

	# --------------------------------------------------
	# user data
	# --------------------------------------------------

	def collect_incoming_data (self, data):
		if self.collector:
			self.collector.collect_incoming_data (data)
		else:
			self.log_info(
				'Dropping %d bytes of incoming request data' % len(data),
				'warning'
				)

	def found_terminator (self):
		if self.collector:
			self.collector.found_terminator()
		else:
			self.log_info (
				'Unexpected end-of-record for incoming request',
				'warning'
				)

	def push (self, thing):
		if type(thing) == type(''):
			self.outgoing.push (producers.simple_producer (thing))
		else:
			self.outgoing.push (thing)

	def response (self, code=200):
		message = self.responses[code]
		self.reply_code = code
		return 'HTTP/%s %d %s' % (self.version, code, message)

	def error (self, code):
		self.reply_code = code
		message = self.responses[code]
		s = self.DEFAULT_ERROR_MESSAGE % {
			'code': code,
			'message': message,
			}
		self['Content-Length'] = len(s)
		self['Content-Type'] = 'text/html'
		# make an error reply
		self.push (s)
		self.done()

	# can also be used for empty replies
	reply_now = error

	def done (self):
		"finalize this transaction - send output to the http channel"

		# ----------------------------------------
		# persistent connection management
		# ----------------------------------------

		#  --- BUCKLE UP! ----

		connection = string.lower (get_header (CONNECTION, self.header))

		close_it = 0
		wrap_in_chunking = 0

		if self.version == '1.0':
			if connection == 'keep-alive':
				if not self.has_key ('Content-Length'):
					close_it = 1
				else:
					self['Connection'] = 'Keep-Alive'
			else:
				close_it = 1
		elif self.version == '1.1':
			if connection == 'close':
				close_it = 1
			elif not self.has_key ('Content-Length'):
				if self.has_key ('Transfer-Encoding'):
					if not self['Transfer-Encoding'] == 'chunked':
						close_it = 1
				elif self.use_chunked:
					self['Transfer-Encoding'] = 'chunked'
					wrap_in_chunking = 1
				else:
					close_it = 1
		elif self.version is None:
			# Although we don't *really* support http/0.9 (because we'd have to
			# use \r\n as a terminator, and it would just yuck up a lot of stuff)
			# it's very common for developers to not want to type a version number
			# when using telnet to debug a server.
			close_it = 1
					
		outgoing_header = producers.simple_producer (self.build_reply_header())

		if close_it:
			self['Connection'] = 'close'

		if wrap_in_chunking:
			outgoing_producer = producers.chunked_producer (
				producers.composite_producer (self.outgoing)
				)
			# prepend the header
			outgoing_producer = producers.composite_producer (
				fifo([outgoing_header, outgoing_producer])
				)
		else:
			# prepend the header
			self.outgoing.push_front (outgoing_header)
			outgoing_producer = producers.composite_producer (self.outgoing)

		# apply a few final transformations to the output
		self.channel.push_with_producer (
			# globbing gives us large packets
			producers.globbing_producer (
				# hooking lets us log the number of bytes sent
				producers.hooked_producer (
					outgoing_producer,
					self.log
					)
				)
			)

		self.channel.current_request = None

		if close_it:
			self.channel.close_when_done()

	def log_date_string (self, when):
		return time.strftime (
			'%d/%b/%Y:%H:%M:%S ',
			time.gmtime(when)
			) + tz_for_log

	def log (self, bytes):
		self.channel.server.logger.log (
			self.channel.addr[0],
			'%d - - [%s] "%s" %d %d\n' % (
				self.channel.addr[1],
				self.log_date_string (time.time()),
				self.request,
				self.reply_code,
				bytes
				)
			)

	responses = {
		100: "Continue",
		101: "Switching Protocols",
		200: "OK",
		201: "Created",
		202: "Accepted",
		203: "Non-Authoritative Information",
		204: "No Content",
		205: "Reset Content",
		206: "Partial Content",
		300: "Multiple Choices",
		301: "Moved Permanently",
		302: "Moved Temporarily",
		303: "See Other",
		304: "Not Modified",
		305: "Use Proxy",
		400: "Bad Request",
		401: "Unauthorized",
		402: "Payment Required",
		403: "Forbidden",
		404: "Not Found",
		405: "Method Not Allowed",
		406: "Not Acceptable",
		407: "Proxy Authentication Required",
		408: "Request Time-out",
		409: "Conflict",
		410: "Gone",
		411: "Length Required",
		412: "Precondition Failed",
		413: "Request Entity Too Large",
		414: "Request-URI Too Large",
		415: "Unsupported Media Type",
		500: "Internal Server Error",
		501: "Not Implemented",
		502: "Bad Gateway",
		503: "Service Unavailable",
		504: "Gateway Time-out",
		505: "HTTP Version not supported"
		}

	# Default error message
	DEFAULT_ERROR_MESSAGE = string.join (
		['<head>',
		 '<title>Error response</title>',
		 '</head>',
		 '<body>',
		 '<h1>Error response</h1>',
		 '<p>Error code %(code)d.',
		 '<p>Message: %(message)s.',
		 '</body>',
		 ''
		 ],
		'\r\n'
		)


# ===========================================================================
#						 HTTP Channel Object
# ===========================================================================

class http_channel (asynchat.async_chat):

	# use a larger default output buffer
	ac_out_buffer_size = 1<<16

	current_request = None
	channel_counter = counter()

	def __init__ (self, server, conn, addr):
		self.channel_number = http_channel.channel_counter.increment()
		self.request_counter = counter()
		asynchat.async_chat.__init__ (self, conn)
		self.server = server
		self.addr = addr
		self.set_terminator ('\r\n\r\n')
		self.in_buffer = ''
		self.creation_time = int (time.time())
		self.check_maintenance()

	def __repr__ (self):
		ar = asynchat.async_chat.__repr__(self)[1:-1]
		return '<%s channel#: %s requests:%s>' % (
			ar,
			self.channel_number,
			self.request_counter
			)

	# Channel Counter, Maintenance Interval...
	maintenance_interval = 500

	def check_maintenance (self):
		if not self.channel_number % self.maintenance_interval:
			self.maintenance()

	def maintenance (self):
		self.kill_zombies()

	# 30-minute zombie timeout.  status_handler also knows how to kill zombies.
	zombie_timeout = 30 * 60

	def kill_zombies (self):
		now = int (time.time())
		for channel in asyncore.socket_map.values():
			if channel.__class__ == self.__class__:
				if (now - channel.creation_time) > channel.zombie_timeout:
					channel.close()

	# --------------------------------------------------
	# send/recv overrides, good place for instrumentation.
	# --------------------------------------------------
	
	# this information needs to get into the request object,
	# so that it may log correctly.
	def send (self, data):
		result = asynchat.async_chat.send (self, data)
		self.server.bytes_out.increment (len(data))
		return result

	def recv (self, buffer_size):
		try:
			result = asynchat.async_chat.recv (self, buffer_size)
			self.server.bytes_in.increment (len(result))
			return result
		except MemoryError:
			# --- Save a Trip to Your Service Provider ---
			# It's possible for a process to eat up all the memory of
			# the machine, and put it in an extremely wedged state,
			# where medusa keeps running and can't be shut down.  This
			# is where MemoryError tends to get thrown, though of
			# course it could get thrown elsewhere.
			sys.exit ("Out of Memory!")

	def handle_error (self):
		t, v = sys.exc_info()[:2]
		if t is SystemExit:
			raise t, v
		else:
			asynchat.async_chat.handle_error (self)

	def log (self, *args):
		pass

	# --------------------------------------------------
	# async_chat methods
	# --------------------------------------------------

	def collect_incoming_data (self, data):
		if self.current_request:
			# we are receiving data (probably POST data) for a request
			self.current_request.collect_incoming_data (data)
		else:
			# we are receiving header (request) data
			self.in_buffer = self.in_buffer + data

	def found_terminator (self):
		if self.current_request:
			self.current_request.found_terminator()
		else:
			header = self.in_buffer
			self.in_buffer = ''
			lines = string.split (header, '\r\n')

			# --------------------------------------------------
			# crack the request header
			# --------------------------------------------------

			while lines and not lines[0]:
				# as per the suggestion of http-1.1 section 4.1, (and
				# Eric Parker <eparker@zyvex.com>), ignore a leading
				# blank lines (buggy browsers tack it onto the end of
				# POST requests)
				lines = lines[1:]

			if not lines:
				self.close_when_done()
				return

			request = lines[0]

			# unquote path if necessary (thanks to Skip Montaro for pointing
			# out that we must unquote in piecemeal fashion).
			if '%' in request:
				request = unquote (request)

			command, uri, version = crack_request (request)
			header = join_headers (lines[1:])

			r = http_request (self, request, command, uri, version, header)
			self.request_counter.increment()
			self.server.total_requests.increment()

			if command is None:
				self.log_info ('Bad HTTP request: %s' % repr(request), 'error')
				r.error (400)
				return

			# --------------------------------------------------
			# handler selection and dispatch
			# --------------------------------------------------
			for h in self.server.handlers:
				if h.match (r):
					try:
						self.current_request = r
						# This isn't used anywhere.
						# r.handler = h # CYCLE
						h.handle_request (r)
					except:
						self.server.exceptions.increment()
						(file, fun, line), t, v, tbinfo = asyncore.compact_traceback()
						self.log_info(
								'Server Error: %s, %s: file: %s line: %s' % (t,v,file,line),
								'error')
						try:
							r.error (500)
						except:
							pass
					return

			# no handlers, so complain
			r.error (404)

	def writable (self):
		# this is just the normal async_chat 'writable', here for comparison
		return self.ac_out_buffer or len(self.producer_fifo)

	def writable_for_proxy (self):
		# this version of writable supports the idea of a 'stalled' producer
		# [i.e., it's not ready to produce any output yet] This is needed by
		# the proxy, which will be waiting for the magic combination of
		# 1) hostname resolved
		# 2) connection made
		# 3) data available.
		if self.ac_out_buffer:
			return 1
		elif len(self.producer_fifo):
			p = self.producer_fifo.first()
			if hasattr (p, 'stalled'):
				return not p.stalled()
			else:
				return 1

# ===========================================================================
#						 HTTP Server Object
# ===========================================================================

class http_server (asyncore.dispatcher):

	SERVER_IDENT = 'HTTP Server (V%s)' % VERSION_STRING

	channel_class = http_channel

	def __init__ (self, ip, port, resolver=None, logger_object=None):
		self.ip = ip
		self.port = port
		asyncore.dispatcher.__init__ (self)
		self.create_socket (socket.AF_INET, socket.SOCK_STREAM)

		self.handlers = []

		if not logger_object:
			logger_object = logger.file_logger (sys.stdout)

		self.set_reuse_addr()
		self.bind ((ip, port))

		# lower this to 5 if your OS complains
		self.listen (1024)

		host, port = self.socket.getsockname()
		if not ip:
			self.log_info('Computing default hostname', 'warning')
			ip = socket.gethostbyname (socket.gethostname())
		try:
			self.server_name = socket.gethostbyaddr (ip)[0]
		except socket.error:
			self.log_info('Cannot do reverse lookup', 'warning')
			self.server_name = ip       # use the IP address as the "hostname"

		self.server_port = port
		self.total_clients = counter()
		self.total_requests = counter()
		self.exceptions = counter()
		self.bytes_out = counter()
		self.bytes_in  = counter()

		if not logger_object:
			logger_object = logger.file_logger (sys.stdout)

		if resolver:
			self.logger = logger.resolving_logger (resolver, logger_object)
		else:
			self.logger = logger.unresolving_logger (logger_object)

		self.log_info (
			'Medusa (V%s) started at %s'
			'\n\tHostname: %s'
			'\n\tPort:%d'
			'\n' % (
				VERSION_STRING,
				time.ctime(time.time()),
				self.server_name,
				port,
				)
			)

	def writable (self):
		return 0

	def handle_read (self):
		pass

	def readable (self):
		return self.accepting

	def handle_connect (self):
		pass

	def handle_accept (self):
		self.total_clients.increment()
		try:
			conn, addr = self.accept()
		except socket.error:
			# linux: on rare occasions we get a bogus socket back from
			# accept.  socketmodule.c:makesockaddr complains that the
			# address family is unknown.  We don't want the whole server
			# to shut down because of this.
			self.log_info ('warning: server accept() threw an exception', 'warning')
			return
		except TypeError:
			# unpack non-sequence.  this can happen when a read event
			# fires on a listening socket, but when we call accept()
			# we get EWOULDBLOCK, so dispatcher.accept() returns None.
			# Seen on FreeBSD3.
			self.log_info ('warning: server accept() threw EWOULDBLOCK', 'warning')
			return

		self.channel_class (self, conn, addr)

	def install_handler (self, handler, back=0):
		if back:
			self.handlers.append (handler)
		else:
			self.handlers.insert (0, handler)

	def remove_handler (self, handler):
		self.handlers.remove (handler)

	def status (self):
		def nice_bytes (n):
			return string.join (status_handler.english_bytes (n))

		handler_stats = filter (None, map (maybe_status, self.handlers))
		
		if self.total_clients:
			ratio = self.total_requests.as_long() / float(self.total_clients.as_long())
		else:
			ratio = 0.0
		
		return producers.composite_producer (
			fifo ([producers.lines_producer (
				['<h2>%s</h2>'							% self.SERVER_IDENT,
				'<br>Listening on: <b>Host:</b> %s'		% self.server_name,
				'<b>Port:</b> %d'						% self.port,
				 '<p><ul>'
				 '<li>Total <b>Clients:</b> %s'			% self.total_clients,
				 '<b>Requests:</b> %s'					% self.total_requests,
				 '<b>Requests/Client:</b> %.1f'			% (ratio),
				 '<li>Total <b>Bytes In:</b> %s'	% (nice_bytes (self.bytes_in.as_long())),
				 '<b>Bytes Out:</b> %s'				% (nice_bytes (self.bytes_out.as_long())),
				 '<li>Total <b>Exceptions:</b> %s'		% self.exceptions,
				 '</ul><p>'
				 '<b>Extension List</b><ul>',
				 ])] + handler_stats + [producers.simple_producer('</ul>')]
				  )
			)

def maybe_status (thing):
	if hasattr (thing, 'status'):
		return thing.status()
	else:
		return None

CONNECTION = re.compile ('Connection: (.*)', re.IGNORECASE)

# merge multi-line headers
# [486dx2: ~500/sec]
def join_headers (headers):
	r = []
	for i in range(len(headers)):
		if headers[i][0] in ' \t':	
			r[-1] = r[-1] + headers[i][1:]
		else:
			r.append (headers[i])
	return r

def get_header (head_reg, lines, group=1):
	for line in lines:
		m = head_reg.match (line)
		if m and m.end() == len(line):
			return m.group (group)
	return ''

def get_header_match (head_reg, lines):
	for line in lines:
		m = head_reg.match (line)
		if m and m.end() == len(line):
			return m
	return ''

REQUEST = re.compile ('([^ ]+) ([^ ]+)(( HTTP/([0-9.]+))$|$)')

def crack_request (r):
	m = REQUEST.match (r)
	if m.end() == len(r):
		if m.group(3):
			version = m.group(5)
		else:
			version = None
		return string.lower (m.group(1)), m.group(2), version
	else:
		return None, None, None

class fifo:
	def __init__ (self, list=None):
		if not list:
			self.list = []
		else:
			self.list = list
		
	def __len__ (self):
		return len(self.list)

	def first (self):
		return self.list[0]

	def push_front (self, object):
		self.list.insert (0, object)

	def push (self, data):
		self.list.append (data)

	def pop (self):
		if self.list:
			result = self.list[0]
			del self.list[0]
			return (1, result)
		else:
			return (0, None)

def compute_timezone_for_log ():
	if time.daylight:
		tz = time.altzone
	else:
		tz = time.timezone
	if tz > 0:
		neg = 1
	else:
		neg = 0
		tz = -tz
	h, rem = divmod (tz, 3600)
	m, rem = divmod (rem, 60)
	if neg:
		return '-%02d%02d' % (h, m)
	else:
		return '+%02d%02d' % (h, m)

# if you run this program over a TZ change boundary, this will be invalid.
tz_for_log = compute_timezone_for_log()

if __name__ == '__main__':
	import sys
	if len(sys.argv) < 2:
		print 'usage: %s <root> <port>' % (sys.argv[0])
	else:
		import monitor
		import filesys
		import default_handler
		import status_handler
		import ftp_server
		import chat_server
		import resolver
		import logger
		rs = resolver.caching_resolver ('127.0.0.1')
		lg = logger.file_logger (sys.stdout)
		ms = monitor.secure_monitor_server ('fnord', '127.0.0.1', 9999)
		fs = filesys.os_filesystem (sys.argv[1])
		dh = default_handler.default_handler (fs)
		hs = http_server ('', string.atoi (sys.argv[2]), rs, lg)
		hs.install_handler (dh)
		ftp = ftp_server.ftp_server (
			ftp_server.dummy_authorizer(sys.argv[1]),
			port=8021,
			resolver=rs,
			logger_object=lg
			)
		cs = chat_server.chat_server ('', 7777)
		sh = status_handler.status_extension([hs,ms,ftp,cs,rs])
		hs.install_handler (sh)
		if ('-p' in sys.argv):
			def profile_loop ():
				try:
					asyncore.loop()
				except KeyboardInterrupt:
					pass
			import profile
			profile.run ('profile_loop()', 'profile.out')
		else:
			asyncore.loop()
