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@adiroiban adiroiban/proxy.py
Created Mar 9, 2018

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"""
Helpers for testing code related to HTTP Proxy .
It provides a context manager for starting the proxy.
Copyright (c) 2017 Adi Roiban.
License BSD
This code is based on HTTP Proxy Server in Python.
:copyright: (c) 2013 by Abhinav Singh.
:license: BSD, see LICENSE for more details.
It was modified to use threading instead of multiprocessing so that it will
work in Windows.
It was also updated to match the needs for our testing, and remove the code
for generic handling.
"""
from __future__ import absolute_import, print_function, unicode_literals
import sys
import threading
import datetime
import socket
import select
import time
# True if we are running on Python 3.
PY3 = sys.version_info[0] == 3
if PY3:
text_type = str
binary_type = bytes
from urllib import parse as urlparse
else:
text_type = unicode
binary_type = str
import urlparse
def text_(s, encoding='utf-8', errors='strict'):
""" If ``s`` is an instance of ``binary_type``, return
``s.decode(encoding, errors)``, otherwise return ``s``"""
if isinstance(s, binary_type):
return s.decode(encoding, errors)
return s # noqa:cover
def bytes_(s, encoding='utf-8', errors='strict'):
""" If ``s`` is an instance of ``text_type``, return
``s.encode(encoding, errors)``, otherwise return ``s``"""
if isinstance(s, text_type): # noqa:cover
return s.encode(encoding, errors)
return s
CRLF, COLON, SP = b'\r\n', b':', b' '
HTTP_REQUEST_PARSER = 1
HTTP_RESPONSE_PARSER = 2
HTTP_PARSER_STATE_INITIALIZED = 1
HTTP_PARSER_STATE_LINE_RCVD = 2
HTTP_PARSER_STATE_RCVING_HEADERS = 3
HTTP_PARSER_STATE_HEADERS_COMPLETE = 4
HTTP_PARSER_STATE_RCVING_BODY = 5
HTTP_PARSER_STATE_COMPLETE = 6
CHUNK_PARSER_STATE_WAITING_FOR_SIZE = 1
CHUNK_PARSER_STATE_WAITING_FOR_DATA = 2
CHUNK_PARSER_STATE_COMPLETE = 3
class LogMixin(object):
"""
Shared code for debugging messages.
"""
def _log(self, message):
if not self._debug:
return
print("%s: %s" % (time.time(), message))
class ChunkParser(object):
"""
HTTP chunked encoding response parser.
"""
def __init__(self):
self.state = CHUNK_PARSER_STATE_WAITING_FOR_SIZE
self.body = b''
self.chunk = b''
self.size = None
def parse(self, data):
more = True if len(data) > 0 else False
while more:
more, data = self.process(data)
def process(self, data):
if self.state == CHUNK_PARSER_STATE_WAITING_FOR_SIZE:
line, data = HttpParser.split(data)
self.size = int(line, 16)
self.state = CHUNK_PARSER_STATE_WAITING_FOR_DATA
elif self.state == CHUNK_PARSER_STATE_WAITING_FOR_DATA:
remaining = self.size - len(self.chunk)
self.chunk += data[:remaining]
data = data[remaining:]
if len(self.chunk) == self.size:
data = data[len(CRLF):]
self.body += self.chunk
if self.size == 0:
self.state = CHUNK_PARSER_STATE_COMPLETE
else:
self.state = CHUNK_PARSER_STATE_WAITING_FOR_SIZE
self.chunk = b''
self.size = None
return len(data) > 0, data
class HttpParser(object):
"""
HTTP request/response parser.
"""
def __init__(self, type=None):
self.state = HTTP_PARSER_STATE_INITIALIZED
self.type = type if type else HTTP_REQUEST_PARSER
self.raw = b''
self.buffer = b''
self.headers = dict()
self.body = None
self.method = None
self.url = None
self.code = None
self.reason = None
self.version = None
self.chunker = None
def parse(self, data):
self.raw += data
data = self.buffer + data
self.buffer = b''
more = True if len(data) > 0 else False
while more:
more, data = self.process(data)
self.buffer = data
def process(self, data):
if (
self.state >= HTTP_PARSER_STATE_HEADERS_COMPLETE and
(self.method == b"POST" or self.type == HTTP_RESPONSE_PARSER)
):
if not self.body:
self.body = b''
if b'content-length' in self.headers:
self.state = HTTP_PARSER_STATE_RCVING_BODY
self.body += data
if len(self.body) >= int(self.headers[b'content-length'][1]):
self.state = HTTP_PARSER_STATE_COMPLETE
elif (
b'transfer-encoding' in self.headers and
self.headers[b'transfer-encoding'][1].lower() == b'chunked'
):
if not self.chunker:
self.chunker = ChunkParser()
self.chunker.parse(data)
if self.chunker.state == CHUNK_PARSER_STATE_COMPLETE:
self.body = self.chunker.body
self.state = HTTP_PARSER_STATE_COMPLETE
return False, b''
line, data = HttpParser.split(data)
if line is False:
return line, data
if self.state < HTTP_PARSER_STATE_LINE_RCVD:
self.process_line(line)
elif self.state < HTTP_PARSER_STATE_HEADERS_COMPLETE:
self.process_header(line)
if (
self.state == HTTP_PARSER_STATE_HEADERS_COMPLETE and
self.type == HTTP_REQUEST_PARSER and
not self.method == b"POST" and
self.raw.endswith(CRLF * 2)
):
self.state = HTTP_PARSER_STATE_COMPLETE
return len(data) > 0, data
def process_line(self, data):
line = data.split(SP)
if self.type == HTTP_REQUEST_PARSER:
self.method = line[0].upper()
self.url = urlparse.urlsplit(line[1])
self.version = line[2]
else:
self.version = line[0]
self.code = line[1]
self.reason = b' '.join(line[2:])
self.state = HTTP_PARSER_STATE_LINE_RCVD
def process_header(self, data):
if len(data) == 0:
if self.state == HTTP_PARSER_STATE_RCVING_HEADERS:
self.state = HTTP_PARSER_STATE_HEADERS_COMPLETE
elif self.state == HTTP_PARSER_STATE_LINE_RCVD:
self.state = HTTP_PARSER_STATE_RCVING_HEADERS
else:
self.state = HTTP_PARSER_STATE_RCVING_HEADERS
parts = data.split(COLON)
key = parts[0].strip()
value = COLON.join(parts[1:]).strip()
self.headers[key.lower()] = (key, value)
def build_url(self):
if not self.url:
return b'/None'
url = self.url.path
if url == b'':
url = b'/'
if not self.url.query == b'':
url += b'?' + self.url.query
if not self.url.fragment == b'':
url += b'#' + self.url.fragment
return url
def build_header(self, k, v):
return k + b": " + v + CRLF
def build(self, del_headers=None, add_headers=None):
req = b" ".join([self.method, self.build_url(), self.version])
req += CRLF
if not del_headers:
del_headers = []
for k in self.headers:
if k not in del_headers:
req += self.build_header(
self.headers[k][0], self.headers[k][1])
if not add_headers:
add_headers = []
for k in add_headers:
req += self.build_header(k[0], k[1])
req += CRLF
if self.body:
req += self.body
return req
@staticmethod
def split(data):
pos = data.find(CRLF)
if pos == -1:
return False, data
line = data[:pos]
data = data[pos + len(CRLF):]
return line, data
class Connection(LogMixin):
"""
TCP server/client connection abstraction.
"""
def __init__(self, what, debug):
self.buffer = b''
self.closed = False
self.what = what # server or client
self._debug = debug
def send(self, data):
return self.conn.send(data)
def recv(self, bytes=8192):
try:
data = self.conn.recv(bytes)
if len(data) == 0:
self._log('recvd 0 bytes from %s' % self.what)
return None
self._log('rcvd %d bytes from %s' % (len(data), self.what))
return data
except Exception as e:
self._log(
'Exception while receiving from connection %s %r '
'with reason %r' % (self.what, self.conn, e)
)
return None
def close(self):
self.conn.close()
self.closed = True
def buffer_size(self):
return len(self.buffer)
def has_buffer(self):
return self.buffer_size() > 0
def queue(self, data):
self.buffer += data
def flush(self):
sent = self.send(self.buffer)
self.buffer = self.buffer[sent:]
self._log('flushed %d bytes to %s' % (sent, self.what))
class ProxyServerConnection(Connection):
"""Establish connection to destination server."""
def __init__(self, host, port, debug):
super(ProxyServerConnection, self).__init__(b'server', debug)
self.addr = (host, int(port))
def connect(self):
self.conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.conn.connect((self.addr[0], self.addr[1]))
class ProxyClientConnection(Connection):
"""Accepted client connection."""
def __init__(self, conn, addr, debug):
super(ProxyClientConnection, self).__init__(b'client', debug)
self.conn = conn
self.addr = addr
class ProxyError(Exception):
pass
class ProxyConnectionFailed(ProxyError):
def __init__(self, host, port, reason):
self.host = host
self.port = port
self.reason = reason
def __str__(self):
return '<ProxyConnectionFailed - %s:%s - %s>' % (
self.host, self.port, self.reason)
class ProxyConnection(LogMixin):
"""
HTTP proxy implementation.
Accepts connection object and act as a proxy between client and server.
Code from proxy_py which removed the multiprocessing usage as it does not
work on Windows.
"""
def __init__(self, client, debug):
super(ProxyConnection, self).__init__()
self.start_time = self._now()
self.last_activity = self.start_time
self.client = client
self.server = None
self.request = HttpParser()
self.response = HttpParser(HTTP_RESPONSE_PARSER)
self.connection_established_pkt = CRLF.join([
b'HTTP/1.1 200 Connection established',
b'Proxy-agent: proxy.py',
CRLF,
])
self._debug = debug
def _now(self):
return datetime.datetime.utcnow()
def _inactive_for(self):
return (self._now() - self.last_activity).seconds
def _is_inactive(self):
return self._inactive_for() > 30
def _process_request(self, data):
# once we have connection to the server
# we don't parse the http request packets
# any further, instead just pipe incoming
# data from client to server
if self.server and not self.server.closed:
self.server.queue(data)
return
# parse http request
self.request.parse(data)
# once http request parser has reached the state complete
# we attempt to establish connection to destination server
if self.request.state == HTTP_PARSER_STATE_COMPLETE:
self._log('request parser is in state complete')
if self.request.method == b"CONNECT":
host, port = self.request.url.path.split(COLON)
elif self.request.url:
if self.request.url.port:
port = self.request.url.port
else:
port = 80
host = self.request.url.hostname
self.server = ProxyServerConnection(host, port, self._debug)
try:
self._log('connecting to server %s:%s' % (host, port))
self.server.connect()
self._log('connected to server %s:%s' % (host, port))
except Exception as e:
self.server.closed = True
raise ProxyConnectionFailed(host, port, repr(e))
# for http connect methods (https requests)
# queue appropriate response for client
# notifying about established connection
if self.request.method == b"CONNECT":
self.client.queue(self.connection_established_pkt)
# for usual http requests, re-build request packet
# and queue for the server with appropriate headers
else:
self.server.queue(self.request.build(
del_headers=[
b'proxy-connection', b'connection', b'keep-alive'],
add_headers=[(b'Connection', b'Close')]
))
def _process_response(self, data):
# parse incoming response packet
# only for non-https requests
if not self.request.method == b"CONNECT":
self.response.parse(data)
# queue data for client
self.client.queue(data)
def _access_log(self):
host, port = self.server.addr if self.server else (None, None)
if self.request.method == b"CONNECT":
self._log(
"%s:%s - %s %s:%s" % (
self.client.addr[0],
self.client.addr[1],
self.request.method, host, port,
))
elif self.request.method:
self._log(
"%s:%s - %s %s:%s%s - %s %s - %s bytes" % (
self.client.addr[0],
self.client.addr[1],
self.request.method,
host,
port,
self.request.build_url(),
self.response.code,
self.response.reason,
len(self.response.raw),
))
def _get_waitable_lists(self):
rlist, wlist, xlist = [self.client.conn], [], []
self._log('*** watching client for read ready')
if self.client.has_buffer():
self._log(
'pending client buffer found, watching client for write ready')
wlist.append(self.client.conn)
if self.server and not self.server.closed:
self._log(
'connection to server exists, watching server for read ready')
rlist.append(self.server.conn)
if self.server and not self.server.closed and self.server.has_buffer():
self._log(
'connection to server exists and pending server buffer found, '
'watching server for write ready'
)
wlist.append(self.server.conn)
return rlist, wlist, xlist
def _process_wlist(self, w):
if self.client.conn in w:
self._log('client is ready for writes, flushing client buffer')
self.client.flush()
if self.server and not self.server.closed and self.server.conn in w:
self._log('server is ready for writes, flushing server buffer')
self.server.flush()
def _process_rlist(self, r):
if self.client.conn in r:
self._log('client is ready for reads, reading')
data = self.client.recv()
self.last_activity = self._now()
if not data:
self._log('client closed connection, breaking')
return True
try:
self._process_request(data)
except ProxyConnectionFailed as e:
self._log(e)
self.client.queue(CRLF.join([
b'HTTP/1.1 502 Bad Gateway',
b'Proxy-agent: proxy.py',
b'Content-Length: 11',
b'Connection: close',
CRLF
]) + b'Bad Gateway')
self.client.flush()
return True
if self.server and not self.server.closed and self.server.conn in r:
self._log('server is ready for reads, reading')
data = self.server.recv()
self.last_activity = self._now()
if not data:
self._log('server closed connection')
self.server.close()
else:
self._process_response(data)
return False
def _process(self):
while True:
rlist, wlist, xlist = self._get_waitable_lists()
r, w, x = select.select(rlist, wlist, xlist, 1)
self._process_wlist(w)
if self._process_rlist(r):
break
if self.client.buffer_size() == 0:
if self.response.state == HTTP_PARSER_STATE_COMPLETE:
self._log(
'client buffer is empty and response state is '
'complete, breaking')
break
if self._is_inactive():
self._log(
'client buffer is empty and maximum '
'inactivity has reached, breaking'
)
break
def start(self):
self._log('Proxying connection %r at address %r' % (
self.client.conn, self.client.addr))
try:
self._process()
except KeyboardInterrupt:
pass
except Exception as e:
self._log(
'Exception while handling connection %r with reason %r' % (
self.client.conn, e))
finally:
self._log(
"closing client connection with pending client "
"buffer size %d bytes" % self.client.buffer_size()
)
self.client.close()
if self.server:
self._log(
"closed client connection with pending server buffer "
"size %d bytes" % self.server.buffer_size()
)
self._access_log()
self._log(
'Closing proxy for connection %r at '
'address %r' % (self.client.conn, self.client.addr))
class SingleThreadedHTTPProxy(threading.Thread, LogMixin):
"""
HTTP Proxy that runs in a single thread.
"""
TIMEOUT = 1
# Class use to handle a connection.
_connection_class = ProxyConnection
def __init__(
self, cond, ip='127.0.0.1', port=0, reject_reason=None, debug=False,
):
threading.Thread.__init__(self)
self.ready = False
self.cond = cond
self._ip = ip
self._port = port
self._debug = debug
self._reject_reason = reject_reason
self.active_connection = None
self.running = False
self._connections = []
@property
def server_address(self):
return self.socket.getsockname()
def run(self):
self.cond.acquire()
self.running = True
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.socket.bind((self._ip, self._port))
self.socket.listen(100)
address = self.server_address
self._log('Proxy start on port %s %d' % (address[0], address[1]))
self.ready = True
if self.cond:
self.cond.notifyAll()
self.cond.release()
# Start the actual HTTP server.
self._acceptConnections()
def _acceptConnections(self):
try:
while True:
if not self.running:
break
conn, addr = self.socket.accept()
if not self.running:
# We got a new connection, but the server is already
# stopped.
break
client = ProxyClientConnection(conn, addr, self._debug)
self.active_connection = conn
self._handle(client)
self.active_connection = None
except Exception as e:
self._log('Proxy error %r' % e)
finally:
self.socket.close()
self._log('Closing proxy')
def _handle(self, client):
if self._reject_reason:
client.send('HTTP/1.1 501 %s\r\n' % (self._reject_reason,))
return
proc = self._connection_class(client, debug=self._debug)
self._connections.append(proc)
self._log('Handle connection %r' % (client.conn.getsockname(),))
proc.start()
class HTTPProxyContext(object):
"""
A context which executes a threaded HTTP proxy.
"""
def __init__(
self, ip='127.0.0.1', port=0, reject_reason=None, debug=False):
self.cond = threading.Condition()
self.server = SingleThreadedHTTPProxy(
cond=self.cond,
ip=ip,
port=port,
reject_reason=reject_reason,
debug=debug,
)
def __enter__(self):
self.cond.acquire()
self.server.start()
# Wait until the server is ready.
while not self.server.ready:
self.cond.wait()
self.cond.release()
from chevah.server.testing.testcase import ServerTestCase
# Even if the thread ready, it might still need some time
# to be ready.
if ServerTestCase.os_version == 'hpux': # noqa:cover
time.sleep(0.1)
else:
time.sleep(0.02)
return self
def __exit__(self, exc_type, exc_value, tb):
self._stopServer()
self.server.join(1)
if self.server.isAlive():
# Even if the thread has joined, it might still need some time
# to close.
time.sleep(0.01)
if self.server.isAlive():
raise AssertionError('Server still running')
return False
@property
def port(self):
return self.server.server_address[1]
@property
def ip(self):
return self.server.server_address[0]
@property
def connections(self):
"""
List of connections made to this proxy.
"""
return self.server._connections
def _stopServer(self):
self.server._reject_reason = None
self.server.running = False
connection = self.server.active_connection
try:
if connection:
# We already have an active ongoing connection
# so we can just stop it.
connection.shutdown(socket.SHUT_RDWR)
connection.close()
else:
# Stop waiting for data from new connection.
# This is done triggering a new connection to unblock the
# accept() call.
close_connection = socket.socket(
socket.AF_INET, socket.SOCK_STREAM)
close_connection.connect((self.ip, self.port))
close_connection.close()
except Exception:
# Maybe the server is already down,
pass
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