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Commit ba21de4a authored by Taddeüs Kroes's avatar Taddeüs Kroes
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Refactored handshaking process, moved it to a separate file, implemented HTTP authentication

parent a215384a
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handshake.py 0 → 100644
View file @ ba21de4a
import os
import re
from hashlib import sha1
from base64 import b64encode
from urlparse import urlparse
from python_digest import build_authorization_request
from errors import HandshakeError
WS_GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
WS_VERSION = '13'
MAX_REDIRECTS = 10
def split_stripped(value, delim=','):
return map(str.strip, str(value).split(delim)) if value else []
class Handshake(object):
def __init__(self, wsock):
self.wsock = wsock
self.sock = wsock.sock
def fail(self, msg):
self.sock.close()
raise HandshakeError(msg)
def receive_request(self):
raw, headers = self.receive_headers()
# Request must be HTTP (at least 1.1) GET request, find the location
match = re.search(r'^GET (.*) HTTP/1.1\r\n', raw)
if match is None:
self.fail('not a valid HTTP 1.1 GET request')
location = match.group(1)
return location, headers
def receive_response(self):
raw, headers = self.receive_headers()
# Response must be HTTP (at least 1.1) with status 101
match = re.search(r'^HTTP/1\.1 (\d{3})', raw)
if match is None:
self.fail('not a valid HTTP 1.1 response')
status = int(match.group(1))
return status, headers
def receive_headers(self):
# Receive entire HTTP header
raw_headers = ''
while raw_headers[-4:] not in ('\r\n\r\n', '\n\n'):
raw_headers += self.sock.recv(512).decode('utf-8', 'ignore')
headers = {}
for key, value in re.findall(r'(.*?): ?(.*?)\r\n', raw_headers):
if key in headers:
headers[key] += ', ' + value
else:
headers[key] = value
return raw_headers, headers
def send_headers(self, headers):
# Send request
for hdr in list(headers):
if isinstance(hdr, tuple):
hdr = '%s: %s' % hdr
self.sock.sendall(hdr + '\r\n')
self.sock.sendall('\r\n')
def perform(self):
raise NotImplementedError
class ServerHandshake(Handshake):
"""
Executes a handshake as the server end point of the socket. If the HTTP
request headers sent by the client are invalid, a HandshakeError is raised.
"""
def perform(self):
# Receive and validate client handshake
location, headers = self.receive_request()
# Send server handshake in response
self.send_headers(self.response_headers(location, headers))
def response_headers(self, location, headers):
# Check if headers that MUST be present are actually present
for name in ('Host', 'Upgrade', 'Connection', 'Sec-WebSocket-Key',
'Sec-WebSocket-Version'):
if name not in headers:
self.fail('missing "%s" header' % name)
# Check WebSocket version used by client
version = headers['Sec-WebSocket-Version']
if version != WS_VERSION:
self.fail('WebSocket version %s requested (only %s is supported)'
% (version, WS_VERSION))
# Verify required header keywords
if 'websocket' not in headers['Upgrade'].lower():
self.fail('"Upgrade" header must contain "websocket"')
if 'upgrade' not in headers['Connection'].lower():
self.fail('"Connection" header must contain "Upgrade"')
# Origin must be present if browser client, and must match the list of
# trusted origins
if 'Origin' not in headers:
if 'User-Agent' in headers:
self.fail('browser client must specify "Origin" header')
if self.wsock.trusted_origins:
self.fail('no "Origin" header specified, assuming untrusted')
origin = 'null'
elif self.wsock.trusted_origins:
origin = headers['Origin']
if origin not in self.wsock.trusted_origins:
self.fail('untrusted origin "%s"' % origin)
# Only a supported protocol can be returned
client_proto = split_stripped(headers['Sec-WebSocket-Protocol']) \
if 'Sec-WebSocket-Protocol' in headers else []
protocol = 'null'
for p in client_proto:
if p in self.wsock.proto:
protocol = p
break
# Only supported extensions are returned
if 'Sec-WebSocket-Extensions' in headers:
client_ext = split_stripped(headers['Sec-WebSocket-Extensions'])
extensions = [e for e in client_ext if e in self.wsock.extensions]
else:
extensions = []
# Encode acceptation key using the WebSocket GUID
key = headers['Sec-WebSocket-Key'].strip()
accept = b64encode(sha1(key + WS_GUID).digest())
# Location scheme differs for SSL-enabled connections
scheme = 'wss' if self.wsock.secure else 'ws'
if 'Host' in headers:
host = headers['Host']
else:
host, port = self.sock.getpeername()
default_port = 443 if self.wsock.secure else 80
if port != default_port:
host += ':%d' % port
# Construct HTTP response header
yield 'HTTP/1.1 101 Web Socket Protocol Handshake'
yield 'Upgrade', 'websocket'
yield 'Connection', 'Upgrade'
yield 'WebSocket-Origin', origin
yield 'WebSocket-Location', '%s://%s%s' % (scheme, host, location)
yield 'Sec-WebSocket-Accept', accept
yield 'Sec-WebSocket-Protocol', protocol
yield 'Sec-WebSocket-Extensions', ', '.join(extensions)
class ClientHandshake(Handshake):
"""
Executes a handshake as the client end point of the socket. May raise a
HandshakeError if the server response is invalid.
"""
def __init__(self, wsock):
Handshake.__init__(self, wsock)
self.redirects = 0
def perform(self):
self.send_headers(self.request_headers())
self.handle_response(*self.receive_response())
def handle_response(self, status, headers):
if status == 101:
self.handle_handshake(headers)
elif status == 401:
self.handle_auth(headers)
elif status in (301, 302, 303, 307, 308):
self.handle_redirect(headers)
else:
self.fail('invalid HTTP response status %d' % status)
def handle_handshake(self, headers):
# Check if headers that MUST be present are actually present
for name in ('Upgrade', 'Connection', 'Sec-WebSocket-Accept'):
if name not in headers:
self.fail('missing "%s" header' % name)
if 'websocket' not in headers['Upgrade'].lower():
self.fail('"Upgrade" header must contain "websocket"')
if 'upgrade' not in headers['Connection'].lower():
self.fail('"Connection" header must contain "Upgrade"')
# Verify accept header
accept = headers['Sec-WebSocket-Accept'].strip()
required_accept = b64encode(sha1(self.key + WS_GUID).digest())
if accept != required_accept:
self.fail('invalid websocket accept header "%s"' % accept)
# Compare extensions
if 'Sec-WebSocket-Extensions' in headers:
server_ext = split_stripped(headers['Sec-WebSocket-Extensions'])
for e in set(server_ext) - set(self.wsock.extensions):
self.fail('server extension "%s" unsupported by client' % e)
for e in set(self.wsock.extensions) - set(server_ext):
self.fail('client extension "%s" unsupported by server' % e)
# Assert that returned protocol (if any) is supported
if 'Sec-WebSocket-Protocol' in headers:
protocol = headers['Sec-WebSocket-Protocol']
if protocol != 'null' and protocol not in self.wsock.protocols:
self.fail('unsupported protocol "%s"' % protocol)
self.wsock.protocol = protocol
def handle_auth(self, headers):
# HTTP authentication is required in the request
hdr = headers['WWW-Authenticate']
authres = dict(re.findall(r'(\w+)[:=] ?"?(\w+)"?', hdr))
mode = hdr.lstrip().split(' ', 1)[0]
if not self.wsock.auth:
self.fail('missing username and password for HTTP authentication')
if mode == 'Basic':
auth_hdr = self.http_auth_basic_headers(**authres)
elif mode == 'Digest':
auth_hdr = self.http_auth_digest_headers(**authres)
else:
self.fail('unsupported HTTP authentication mode "%s"' % mode)
# Send new, authenticated handshake
self.send_headers(list(self.request_headers()) + list(auth_hdr))
self.handle_response(*self.receive_response())
def handle_redirect(self, headers):
self.redirects += 1
if self.redirects > MAX_REDIRECTS:
self.fail('reached maximum number of redirects (%d)'
% MAX_REDIRECTS)
# Handle HTTP redirect
url = urlparse(headers['Location'].strip())
# Reconnect socket to new host if net location changed
if not url.port:
url.port = 443 if self.secure else 80
addr = (url.netloc, url.port)
if addr != self.sock.getpeername():
self.sock.close()
self.sock.connect(addr)
# Update websocket object and send new handshake
self.wsock.location = url.path
self.perform()
def request_headers(self):
if len(self.wsock.location) == 0:
self.fail('request location is empty')
# Generate a 16-byte random base64-encoded key for this connection
self.key = b64encode(os.urandom(16))
# Send client handshake
yield 'GET %s HTTP/1.1' % self.wsock.location
yield 'Host', '%s:%d' % self.sock.getpeername()
yield 'Upgrade', 'websocket'
yield 'Connection', 'keep-alive, Upgrade'
yield 'Sec-WebSocket-Key', self.key
yield 'Sec-WebSocket-Version', WS_VERSION
if self.wsock.origin:
yield 'Origin', self.wsock.origin
# These are for eagerly caching webservers
yield 'Pragma', 'no-cache'
yield 'Cache-Control', 'no-cache'
# Request protocols and extension, these are later checked with the
# actual supported values from the server's response
if self.wsock.protocols:
yield 'Sec-WebSocket-Protocol', ', '.join(self.wsock.protocols)
if self.wsock.extensions:
yield 'Sec-WebSocket-Extensions', ', '.join(self.wsock.extensions)
def http_auth_basic_headers(self, **kwargs):
u, p = self.wsock.auth
u = u.encode('utf-8')
p = p.encode('utf-8')
yield 'Authorization', 'Basic ' + b64encode(u + ':' + p)
def http_auth_digest_headers(self, **kwargs):
username, password = self.wsock.auth
yield 'Authorization', build_authorization_request(
username=username.encode('utf-8'),
method='GET',
uri=self.wsock.location,
nonce_count=0,
realm=kwargs['realm'],
nonce=kwargs['nonce'],
opaque=kwargs['opaque'],
password=password.encode('utf-8'))
python_digest.py 0 → 100644
View file @ ba21de4a
'''
Copyright (c) 2009, Akoha, Inc.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* Neither the name of python-digest nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
'''
try:
import hashlib as md5
except ImportError: # Python <2.5
import md5
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
import random
import types
import urllib
import urlparse
import logging
# Make sure a NullHandler is available
# This was added in Python 2.7/3.2
try:
from logging import NullHandler
except ImportError:
class NullHandler(logging.Handler):
def emit(self, record):
pass
_REQUIRED_DIGEST_RESPONSE_PARTS = ['username', 'realm', 'nonce', 'uri', 'response', 'algorithm',
'opaque', 'qop', 'nc', 'cnonce']
_REQUIRED_DIGEST_CHALLENGE_PARTS = ['realm', 'nonce', 'stale', 'algorithm',
'opaque', 'qop']
l = logging.getLogger(__name__)
l.addHandler(NullHandler())
_LWS=[chr(9), ' ', '\r', '\n']
_ILLEGAL_TOKEN_CHARACTERS = (
[chr(n) for n in range(0-31)] + # control characters
[chr(127)] + # DEL
['(',')','<','>','@',',',';',':','\\','"','/','[',']','?','=','{','}',' '] +
[chr(9)]) # horizontal tab
class State(object):
def character(self, c):
return self.consume(c)
def close(self):
return self.eof()
def eof(self):
raise ValueError('EOF not permitted in this state.')
'''
Return False to keep the current state, or True to pop it
'''
def consume(c):
raise Exception('Unimplemented')
class ParentState(State):
def __init__(self):
super(State, self).__init__()
self.child = None
def close(self):
if self.child:
return self.handle_child_return(self.child.close())
else:
return self.eof()
def push_child(self, child, c=None):
self.child = child
if c is not None:
return self.send_to_child(c)
else:
return False
def send_to_child(self, c):
return self.handle_child_return(self.child.character(c))
def handle_child_return(self, returned_value):
if returned_value:
child = self.child
self.child = None
return self.child_complete(child)
return False
'''
Return False to keep the current state, or True to pop it.
'''
def child_complete(self, child):
return False
def character(self, c):
if self.child:
return self.send_to_child(c)
else:
return self.consume(c)
def consume(self, c):
return False
class EscapedCharacterState(State):
def __init__(self, io):
super(EscapedCharacterState, self).__init__()
self.io = io
def consume(self, c):
self.io.write(c)
return True
class KeyTrailingWhitespaceState(State):
def consume(self, c):
if c in _LWS:
return False
elif c == '=':
return True
else:
raise ValueError("Expected whitespace or '='")
class ValueLeadingWhitespaceState(ParentState):
def __init__(self, io):
super(ValueLeadingWhitespaceState, self).__init__()
self.io = io
def consume(self, c):
if c in _LWS:
return False
elif c == '"':
return self.push_child(QuotedValueState(self.io))
elif c in _ILLEGAL_TOKEN_CHARACTERS:
raise ValueError('The character %r is not a legal token character' % c)
else:
self.io.write(c)
return self.push_child(UnquotedValueState(self.io))
def child_complete(self, child):
return True
class ValueTrailingWhitespaceState(State):
def eof(self):
return True
def consume(self, c):
if c in _LWS:
return False
elif c == ',':
return True
else:
raise ValueError("Expected whitespace, ',', or EOF")
class BaseQuotedState(ParentState):
def __init__(self, io):
super(BaseQuotedState, self).__init__()
self.key_io = io
def consume(self, c):
if c == '\\':
return self.push_child(EscapedCharacterState(self.key_io))
elif c == '"':
return self.push_child(self.TrailingWhitespaceState())
else:
self.key_io.write(c)
return False
def child_complete(self, child):
if type(child) == EscapedCharacterState:
return False
elif type(child) == self.TrailingWhitespaceState:
return True
class BaseUnquotedState(ParentState):
def __init__(self, io):
super(BaseUnquotedState, self).__init__()
self.io = io
def consume(self, c):
if c == self.terminating_character:
return True
elif c in _LWS:
return self.push_child(self.TrailingWhitespaceState())
elif c in _ILLEGAL_TOKEN_CHARACTERS:
raise ValueError('The character %r is not a legal token character' % c)
else:
self.io.write(c)
return False
def child_complete(self, child):
# type(child) == self.TrailingWhitespaceState
return True
class QuotedKeyState(BaseQuotedState):
TrailingWhitespaceState = KeyTrailingWhitespaceState
class QuotedValueState(BaseQuotedState):
TrailingWhitespaceState = ValueTrailingWhitespaceState
class UnquotedKeyState(BaseUnquotedState):
TrailingWhitespaceState = KeyTrailingWhitespaceState
terminating_character = '='
class UnquotedValueState(BaseUnquotedState):
TrailingWhitespaceState = ValueTrailingWhitespaceState
terminating_character = ','
def eof(self):
return True
class NewPartState(ParentState):
def __init__(self, parts):
super(NewPartState, self).__init__()
self.parts = parts
self.key_io = StringIO()
self.value_io = StringIO()
def consume(self, c):
if c in _LWS:
return False
elif c == '"':
return self.push_child(QuotedKeyState(self.key_io))
elif c in _ILLEGAL_TOKEN_CHARACTERS:
raise ValueError('The character %r is not a legal token character' % c)
else:
self.key_io.write(c)
return self.push_child(UnquotedKeyState(self.key_io))
def child_complete(self, child):
if type(child) in [QuotedKeyState, UnquotedKeyState]:
return self.push_child(ValueLeadingWhitespaceState(self.value_io))
else:
self.parts[self.key_io.getvalue()] = self.value_io.getvalue()
return True
class FoundationState(ParentState):
def __init__(self, defaults):
super(FoundationState, self).__init__()
self.parts = defaults.copy()
def result(self):
return self.parts
def consume(self, c):
return self.push_child(NewPartState(self.parts), c)
def parse_parts(parts_string, defaults={}):
state_machine = FoundationState(defaults)
index = 0
try:
for c in parts_string:
state_machine.character(c)
index += 1
state_machine.close()
return state_machine.result()
except ValueError, e:
annotated_parts_string = "%s[%s]%s" % (parts_string[0:index],
index < len(parts_string) and parts_string[index] or '',
index + 1 < len(parts_string) and parts_string[index+1:] or '')
l.exception("Failed to parse the Digest string "
"(offending character is in []): %r" % annotated_parts_string)
return None
def format_parts(**kwargs):
return ", ".join(['%s="%s"' % (k,v.encode('utf-8')) for (k,v) in kwargs.items()])
def validate_uri(digest_uri, request_path):
digest_url_components = urlparse.urlparse(digest_uri)
return urllib.unquote(digest_url_components[2]) == request_path
def validate_nonce(nonce, secret):
'''
Is the nonce one that was generated by this library using the provided secret?
'''
nonce_components = nonce.split(':', 2)
if not len(nonce_components) == 3:
return False
timestamp = nonce_components[0]
salt = nonce_components[1]
nonce_signature = nonce_components[2]
calculated_nonce = calculate_nonce(timestamp, secret, salt)
if not nonce == calculated_nonce:
return False
return True
def calculate_partial_digest(username, realm, password):
'''
Calculate a partial digest that may be stored and used to authenticate future
HTTP Digest sessions.
'''
return md5.md5("%s:%s:%s" % (username.encode('utf-8'), realm, password.encode('utf-8'))).hexdigest()
def build_digest_challenge(timestamp, secret, realm, opaque, stale):
'''
Builds a Digest challenge that may be sent as the value of the 'WWW-Authenticate' header
in a 401 or 403 response.
'opaque' may be any value - it will be returned by the client.
'timestamp' will be incorporated and signed in the nonce - it may be retrieved from the
client's authentication request using get_nonce_timestamp()
'''
nonce = calculate_nonce(timestamp, secret)
return 'Digest %s' % format_parts(realm=realm, qop='auth', nonce=nonce,
opaque=opaque, algorithm='MD5',
stale=stale and 'true' or 'false')
def calculate_request_digest(method, partial_digest, digest_response=None,
uri=None, nonce=None, nonce_count=None, client_nonce=None):
'''
Calculates a value for the 'response' value of the client authentication request.
Requires the 'partial_digest' calculated from the realm, username, and password.
Either call it with a digest_response to use the values from an authentication request,
or pass the individual parameters (i.e. to generate an authentication request).
'''
if digest_response:
if uri or nonce or nonce_count or client_nonce:
raise Exception("Both digest_response and one or more "
"individual parameters were sent.")
uri = digest_response.uri
nonce = digest_response.nonce
nonce_count = digest_response.nc
client_nonce=digest_response.cnonce
elif not (uri and nonce and (nonce_count != None) and client_nonce):
raise Exception("Neither digest_response nor all individual parameters were sent.")
ha2 = md5.md5("%s:%s" % (method, uri)).hexdigest()
data = "%s:%s:%s:%s:%s" % (nonce, "%08x" % nonce_count, client_nonce, 'auth', ha2)
kd = md5.md5("%s:%s" % (partial_digest, data)).hexdigest()
return kd
def get_nonce_timestamp(nonce):
'''
Extract the timestamp from a Nonce. To be sure the timestamp was generated by this site,
make sure you validate the nonce using validate_nonce().
'''
components = nonce.split(':',2)
if not len(components) == 3:
return None
try:
return float(components[0])
except ValueError:
return None
def calculate_nonce(timestamp, secret, salt=None):
'''
Generate a nonce using the provided timestamp, secret, and salt. If the salt is not provided,
(and one should only be provided when validating a nonce) one will be generated randomly
in order to ensure that two simultaneous requests do not generate identical nonces.
'''
if not salt:
salt = ''.join([random.choice('0123456789ABCDEF') for x in range(4)])
return "%s:%s:%s" % (timestamp, salt,
md5.md5("%s:%s:%s" % (timestamp, salt, secret)).hexdigest())
def build_authorization_request(username, method, uri, nonce_count, digest_challenge=None,
realm=None, nonce=None, opaque=None, password=None,
request_digest=None, client_nonce=None):
'''
Builds an authorization request that may be sent as the value of the 'Authorization'
header in an HTTP request.
Either a digest_challenge object (as returned from parse_digest_challenge) or its required
component parameters (nonce, realm, opaque) must be provided.
The nonce_count should be the last used nonce_count plus one.
Either the password or the request_digest should be provided - if provided, the password
will be used to generate a request digest. The client_nonce is optional - if not provided,
a random value will be generated.
'''
if not client_nonce:
client_nonce = ''.join([random.choice('0123456789ABCDEF') for x in range(32)])
if digest_challenge and (realm or nonce or opaque):
raise Exception("Both digest_challenge and one or more of realm, nonce, and opaque"
"were sent.")
if digest_challenge:
if isinstance(digest_challenge, types.StringType):
digest_challenge_header = digest_challenge
digest_challenge = parse_digest_challenge(digest_challenge_header)
if not digest_challenge:
raise Exception("The provided digest challenge header could not be parsed: %s" %
digest_challenge_header)
realm = digest_challenge.realm
nonce = digest_challenge.nonce
opaque = digest_challenge.opaque
elif not (realm and nonce and opaque):
raise Exception("Either digest_challenge or realm, nonce, and opaque must be sent.")
if password and request_digest:
raise Exception("Both password and calculated request_digest were sent.")
elif not request_digest:
if not password:
raise Exception("Either password or calculated request_digest must be provided.")
partial_digest = calculate_partial_digest(username, realm, password)
request_digest = calculate_request_digest(method, partial_digest, uri=uri, nonce=nonce,
nonce_count=nonce_count,
client_nonce=client_nonce)
return 'Digest %s' % format_parts(username=username, realm=realm, nonce=nonce, uri=uri,
response=request_digest, algorithm='MD5', opaque=opaque,
qop='auth', nc='%08x' % nonce_count, cnonce=client_nonce)
def _check_required_parts(parts, required_parts):
if parts == None:
return False
missing_parts = [part for part in required_parts if not part in parts]
return len(missing_parts) == 0
def _build_object_from_parts(parts, names):
obj = type("", (), {})()
for part_name in names:
val = parts[part_name]
if isinstance(val, basestring):
val = unicode(val, "utf-8")
setattr(obj, part_name, val)
return obj
def parse_digest_response(digest_response_string):
'''
Parse the parameters of a Digest response. The input is a comma separated list of
token=(token|quoted-string). See RFCs 2616 and 2617 for details.
Known issue: this implementation will fail if there are commas embedded in quoted-strings.
'''
parts = parse_parts(digest_response_string, defaults={'algorithm': 'MD5'})
if not _check_required_parts(parts, _REQUIRED_DIGEST_RESPONSE_PARTS):
return None
if not parts['nc'] or [c for c in parts['nc'] if not c in '0123456789abcdefABCDEF']:
return None
parts['nc'] = int(parts['nc'], 16)
digest_response = _build_object_from_parts(parts, _REQUIRED_DIGEST_RESPONSE_PARTS)
if ('MD5', 'auth') != (digest_response.algorithm, digest_response.qop):
return None
return digest_response
def is_digest_credential(authorization_header):
'''
Determines if the header value is potentially a Digest response sent by a client (i.e.
if it starts with 'Digest ' (case insensitive).
'''
return authorization_header[:7].lower() == 'digest '
def parse_digest_credentials(authorization_header):
'''
Parses the value of an 'Authorization' header. Returns an object with properties
corresponding to each of the recognized parameters in the header.
'''
if not is_digest_credential(authorization_header):
return None
return parse_digest_response(authorization_header[7:])
def is_digest_challenge(authentication_header):
'''
Determines if the header value is potentially a Digest challenge sent by a server (i.e.
if it starts with 'Digest ' (case insensitive).
'''
return authentication_header[:7].lower() == 'digest '
def parse_digest_challenge(authentication_header):
'''
Parses the value of a 'WWW-Authenticate' header. Returns an object with properties
corresponding to each of the recognized parameters in the header.
'''
if not is_digest_challenge(authentication_header):
return None
parts = parse_parts(authentication_header[7:], defaults={'algorithm': 'MD5',
'stale': 'false'})
if not _check_required_parts(parts, _REQUIRED_DIGEST_CHALLENGE_PARTS):
return None
parts['stale'] = parts['stale'].lower() == 'true'
digest_challenge = _build_object_from_parts(parts, _REQUIRED_DIGEST_CHALLENGE_PARTS)
if ('MD5', 'auth') != (digest_challenge.algorithm, digest_challenge.qop):
return None
return digest_challenge
websocket.py
View file @ ba21de4a
import os
import re
import socket
import ssl
from hashlib import sha1
from base64 import b64encode
from urlparse import urlparse
from frame import receive_frame
from errors import HandshakeError, SSLError
WS_GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
WS_VERSION = '13'
def split_stripped(value, delim=','):
return map(str.strip, str(value).split(delim)) if value else []
from handshake import ServerHandshake, ClientHandshake
from errors import SSLError
class websocket(object):
......@@ -38,12 +26,13 @@ class websocket(object):
Client example:
>>> import twspy
>>> sock = twspy.websocket()
>>> sock = twspy.websocket(location='/my/path')
>>> sock.connect(('', 8000))
>>> sock.send(twspy.Frame(twspy.OPCODE_TEXT, 'Hello, Server!'))
"""
def __init__(self, sock=None, protocols=[], extensions=[], origin=None,
trusted_origins=[], sfamily=socket.AF_INET, sproto=0):
trusted_origins=[], location='/', auth=None,
sfamily=socket.AF_INET, sproto=0):
"""
Create a regular TCP socket of family `family` and protocol
......@@ -62,15 +51,23 @@ class websocket(object):
has value not in this list, a HandshakeError is raised. If the list is
empty (default), all origins are excepted.
`location` is optional, used for the HTTP handshake. In a URL, this
would show as ws://host[:port]/path.
`auth` is optional, used for HTTP Basic or Digest authentication during
the handshake. It must be specified as a (username, password) tuple.
`sfamily` and `sproto` are used for the regular socket constructor.
"""
self.protocols = protocols
self.extensions = extensions
self.origin = origin
self.trusted_origins = trusted_origins
self.location = location
self.auth = auth
self.sock = sock or socket.socket(sfamily, socket.SOCK_STREAM, sproto)
self.secure = False
self.handshake_started = False
self.handshake_sent = False
def bind(self, address):
self.sock.bind(address)
......@@ -87,24 +84,20 @@ class websocket(object):
"""
sock, address = self.sock.accept()
wsock = websocket(sock)
wsock.server_handshake()
ServerHandshake(wsock).perform()
wsock.handshake_sent = True
return wsock, address
def connect(self, address, path='/', auth=None):
def connect(self, address):
"""
Equivalent to socket.connect(), but sends an client handshake request
after connecting.
`address` is a (host, port) tuple of the server to connect to.
`path` is optional, used as the *location* part of the HTTP handshake.
In a URL, this would show as ws://host[:port]/path.
`auth` is optional, used for the HTTP "Authorization" header of the
handshake request.
"""
self.sock.connect(address)
self.client_handshake(address, path, auth)
ClientHandshake(self).perform()
self.handshake_sent = True
def send(self, *args):
"""
......@@ -145,243 +138,13 @@ class websocket(object):
def close(self):
self.sock.close()
def server_handshake(self):
"""
Execute a handshake as the server end point of the socket. If the HTTP
request headers sent by the client are invalid, a HandshakeError
is raised.
"""
def fail(msg):
self.sock.close()
raise HandshakeError(msg)
# Receive HTTP header
raw_headers = ''
while raw_headers[-4:] not in ('\r\n\r\n', '\n\n'):
raw_headers += self.sock.recv(512).decode('utf-8', 'ignore')
# Request must be HTTP (at least 1.1) GET request, find the location
match = re.search(r'^GET (.*) HTTP/1.1\r\n', raw_headers)
if match is None:
fail('not a valid HTTP 1.1 GET request')
location = match.group(1)
headers = re.findall(r'(.*?): ?(.*?)\r\n', raw_headers)
header_names = [name for name, value in headers]
def header(name):
return ', '.join([v for n, v in headers if n == name])
# Check if headers that MUST be present are actually present
for name in ('Host', 'Upgrade', 'Connection', 'Sec-WebSocket-Key',
'Sec-WebSocket-Version'):
if name not in header_names:
fail('missing "%s" header' % name)
# Check WebSocket version used by client
version = header('Sec-WebSocket-Version')
if version != WS_VERSION:
fail('WebSocket version %s requested (only %s '
'is supported)' % (version, WS_VERSION))
# Verify required header keywords
if 'websocket' not in header('Upgrade').lower():
fail('"Upgrade" header must contain "websocket"')
if 'upgrade' not in header('Connection').lower():
fail('"Connection" header must contain "Upgrade"')
# Origin must be present if browser client, and must match the list of
# trusted origins
if 'Origin' not in header_names:
if 'User-Agent' in header_names:
fail('browser client must specify "Origin" header')
if self.trusted_origins:
fail('no "Origin" header specified, assuming untrusted')
elif self.trusted_origins:
origin = header('Origin')
if origin not in self.trusted_origins:
fail('untrusted origin "%s"' % origin)
# Only supported protocols are returned
client_protocols = split_stripped(header('Sec-WebSocket-Extensions'))
protocol = 'null'
for p in client_protocols:
if p in self.protocols:
protocol = p
break
# Only supported extensions are returned
extensions = split_stripped(header('Sec-WebSocket-Extensions'))
extensions = [e for e in extensions if e in self.extensions]
# Encode acceptation key using the WebSocket GUID
key = header('Sec-WebSocket-Key').strip()
accept = b64encode(sha1(key + WS_GUID).digest())
# Construct HTTP response header
shake = 'HTTP/1.1 101 Web Socket Protocol Handshake\r\n'
shake += 'Upgrade: websocket\r\n'
shake += 'Connection: Upgrade\r\n'
shake += 'WebSocket-Origin: %s\r\n' % header('Origin')
shake += 'WebSocket-Location: ws://%s%s\r\n' \
% (header('Host'), location)
shake += 'Sec-WebSocket-Accept: %s\r\n' % accept
shake += 'Sec-WebSocket-Protocol: %s\r\n' % protocol
shake += 'Sec-WebSocket-Extensions: %s\r\n' % ', '.join(extensions)
self.sock.sendall(shake + '\r\n')
self.handshake_started = True
def client_handshake(self, address, location, auth):
"""
Executes a handshake as the client end point of the socket. May raise a
HandshakeError if the server response is invalid.
"""
def fail(msg):
self.sock.close()
raise HandshakeError(msg)
def send_request(location):
if len(location) == 0:
fail('request location is empty')
# Generate a 16-byte random base64-encoded key for this connection
key = b64encode(os.urandom(16))
# Send client handshake
shake = 'GET %s HTTP/1.1\r\n' % location
shake += 'Host: %s:%d\r\n' % address
shake += 'Upgrade: websocket\r\n'
shake += 'Connection: keep-alive, Upgrade\r\n'
shake += 'Sec-WebSocket-Key: %s\r\n' % key
shake += 'Sec-WebSocket-Version: %s\r\n' % WS_VERSION
if self.origin:
shake += 'Origin: %s\r\n' % self.origin
# These are for eagerly caching webservers
shake += 'Pragma: no-cache\r\n'
shake += 'Cache-Control: no-cache\r\n'
# Request protocols and extension, these are later checked with the
# actual supported values from the server's response
if self.protocols:
shake += 'Sec-WebSocket-Protocol: %s\r\n' \
% ', '.join(self.protocols)
if self.extensions:
shake += 'Sec-WebSocket-Extensions: %s\r\n' \
% ', '.join(self.extensions)
if auth:
shake += 'Authorization: %s\r\n' % auth
self.sock.sendall(shake + '\r\n')
return key
def receive_response(key):
# Receive and process server handshake
raw_headers = ''
while raw_headers[-4:] not in ('\r\n\r\n', '\n\n'):
raw_headers += self.sock.recv(512).decode('utf-8', 'ignore')
# Response must be HTTP (at least 1.1) with status 101
match = re.search(r'^HTTP/1\.1 (\d{3})', raw_headers)
if match is None:
fail('not a valid HTTP 1.1 response')
status = int(match.group(1))
headers = re.findall(r'(.*?): ?(.*?)\r\n', raw_headers)
header_names = [name for name, value in headers]
def header(name):
return ', '.join([v for n, v in headers if n == name])
if status == 401:
# HTTP authentication is required in the request
raise HandshakeError('HTTP authentication required: %s'
% header('WWW-Authenticate'))
if status in (301, 302, 303, 307, 308):
# Handle HTTP redirect
url = urlparse(header('Location').strip())
# Reconnect socket if net location changed
if not url.port:
url.port = 443 if self.secure else 80
addr = (url.netloc, url.port)
if addr != self.sock.getpeername():
self.sock.close()
self.sock.connect(addr)
# Send new handshake
receive_response(send_request(url.path))
return
if status != 101:
# 101 means server has accepted the connection and sent
# handshake headers
fail('invalid HTTP response status %d' % status)
# Check if headers that MUST be present are actually present
for name in ('Upgrade', 'Connection', 'Sec-WebSocket-Accept'):
if name not in header_names:
fail('missing "%s" header' % name)
if 'websocket' not in header('Upgrade').lower():
fail('"Upgrade" header must contain "websocket"')
if 'upgrade' not in header('Connection').lower():
fail('"Connection" header must contain "Upgrade"')
# Verify accept header
accept = header('Sec-WebSocket-Accept').strip()
required_accept = b64encode(sha1(key + WS_GUID).digest())
if accept != required_accept:
fail('invalid websocket accept header "%s"' % accept)
# Compare extensions
server_ext = split_stripped(header('Sec-WebSocket-Extensions'))
for e in server_ext:
if e not in self.extensions:
fail('server extension "%s" is unsupported by client' % e)
for e in self.extensions:
if e not in server_ext:
fail('client extension "%s" is unsupported by server' % e)
# Assert that returned protocol (if any) is supported
protocol = header('Sec-WebSocket-Protocol')
if protocol:
if protocol != 'null' and protocol not in self.protocols:
fail('unsupported protocol "%s"' % protocol)
self.protocol = protocol
self.handshake_started = True
receive_response(send_request(location))
def enable_ssl(self, *args, **kwargs):
"""
Transforms the regular socket.socket to an ssl.SSLSocket for secure
connections. Any arguments are passed to ssl.wrap_socket:
http://docs.python.org/dev/library/ssl.html#ssl.wrap_socket
"""
if self.handshake_started:
if self.handshake_sent:
raise SSLError('can only enable SSL before handshake')
self.secure = True
......
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