class SslClient(object):
"""High level API implementing an SSL client.
"""
def __init__(self, sock=None, ssl_version=SSLV23, ssl_verify=SSL_VERIFY_PEER, ssl_verify_locations=None,
client_certchain_file=None, client_key_file=None, client_key_type=SSL_FILETYPE_PEM,
client_key_password='', ignore_client_authentication_requests=False):
# type: (socket.socket, int, int, str, str, str, int, str, bool) -> None
# A Python socket handles transmission of the data
self._sock = sock
self._is_handshake_completed = False
self._client_CA_list = []
# OpenSSL objects
# SSL_CTX
self._ssl_ctx = SSL_CTX(ssl_version)
self._ssl_ctx.set_verify(ssl_verify)
if ssl_verify_locations:
self._ssl_ctx.load_verify_locations(ssl_verify_locations)
if client_certchain_file is not None:
self._use_private_key(client_certchain_file, client_key_file, client_key_type, client_key_password)
if ignore_client_authentication_requests:
if client_certchain_file:
raise ValueError('Cannot enable both client_certchain_file and ignore_client_authentication_requests')
self._ssl_ctx.set_client_cert_cb_NULL()
# SSL
self._ssl = SSL(self._ssl_ctx)
self._ssl.set_connect_state()
# Specific servers do not reply to a client hello that is bigger than 255 bytes
# See http://rt.openssl.org/Ticket/Display.html?id=2771&user=guest&pass=guest
# So we make the default cipher list smaller (to make the client hello smaller)
if ssl_version != SSLV2: # This makes SSLv2 fail
self._ssl.set_cipher_list('HIGH:-aNULL:-eNULL:-3DES:-SRP:-PSK:-CAMELLIA')
else:
# Handshake workaround for SSL2 + IIS 7
self.do_handshake = self.do_ssl2_iis_handshake
# BIOs
self._internal_bio = BIO()
self._network_bio = BIO()
# http://www.openssl.org/docs/crypto/BIO_s_bio.html
BIO.make_bio_pair(self._internal_bio, self._network_bio)
self._ssl.set_bio(self._internal_bio)
def do_handshake(self):
# type: () -> None
if self._sock is None:
# TODO: Auto create a socket ?
raise IOError('Internal socket set to None; cannot perform handshake.')
while True:
try:
self._ssl.do_handshake()
self._is_handshake_completed = True
# Handshake was successful
return
except WantReadError:
# OpenSSL is expecting more data from the peer
# Send available handshake data to the peer
self._flush_ssl_engine()
# Recover the peer's encrypted response
handshake_data_in = self._sock.recv(DEFAULT_BUFFER_SIZE)
if len(handshake_data_in) == 0:
raise IOError('Nassl SSL handshake failed: peer did not send data back.')
# Pass the data to the SSL engine
self._network_bio.write(handshake_data_in)
except WantX509LookupError:
# Server asked for a client certificate and we didn't provide one
raise ClientCertificateRequested(self.get_client_CA_list())
def do_ssl2_iis_handshake(self):
# type: () -> None
if self._sock is None:
# TODO: Auto create a socket ?
raise IOError('Internal socket set to None; cannot perform handshake.')
while True:
try:
self._ssl.do_handshake()
self._is_handshake_completed = True
# Handshake was successful
return
except WantReadError:
# OpenSSL is expecting more data from the peer
# Send available handshake data to the peer
lengh_to_read = self._network_bio.pending()
while lengh_to_read:
# Get the data from the SSL engine
handshake_data_out = self._network_bio.read(lengh_to_read)
if 'SSLv2 read server verify A' in self._ssl.state_string_long():
# Awful h4ck for SSLv2 when connecting to IIS7 (like in the 90s)
# OpenSSL sends the client's CMK and data message in the same packet without
# waiting for the server's response, causing IIS 7 to hang on the connection.
# This workaround forces our client to send the CMK message, then wait for the server's
# response, and then send the data packet
if '\x02' in handshake_data_out[2]: # Make sure we're looking at the CMK message
# cmk_size = handshake_data_out[0:2]
test1 = int(handshake_data_out[0].encode('hex'), base=16)
test2 = int(handshake_data_out[1].encode('hex'), base=16)
test1 = (test1 & 0x7f) << 8
size = test1 + test2
# Manually split the two records to force them to be sent separately
cmk_packet = handshake_data_out[0:size+2]
data_packet = handshake_data_out[size+2::]
self._sock.send(cmk_packet)
handshake_data_in = self._sock.recv(DEFAULT_BUFFER_SIZE)
# print repr(handshake_data_in)
if len(handshake_data_in) == 0:
raise IOError('Nassl SSL handshake failed: peer did not send data back.')
# Pass the data to the SSL engine
self._network_bio.write(handshake_data_in)
handshake_data_out = data_packet
# Send it to the peer
self._sock.send(handshake_data_out)
lengh_to_read = self._network_bio.pending()
handshake_data_in = self._sock.recv(DEFAULT_BUFFER_SIZE)
if len(handshake_data_in) == 0:
raise IOError('Nassl SSL handshake failed: peer did not send data back.')
# Pass the data to the SSL engine
self._network_bio.write(handshake_data_in)
except WantX509LookupError:
# Server asked for a client certificate and we didn't provide one
raise ClientCertificateRequested(self.get_client_CA_list())
def read(self, size):
# type: (int) -> str
if not self._is_handshake_completed:
raise IOError('SSL Handshake was not completed; cannot receive data.')
while True:
# Receive available encrypted data from the peer
encrypted_data = self._sock.recv(DEFAULT_BUFFER_SIZE)
if len(encrypted_data) == 0:
raise IOError('Could not read() - peer closed the connection.')
# Pass it to the SSL engine
self._network_bio.write(encrypted_data)
try:
# Try to read the decrypted data
decrypted_data = self._ssl.read(size)
return decrypted_data
except WantReadError:
# The SSL engine needs more data
# before it can decrypt the whole message
pass
def write(self, data):
# type: (str) -> int
"""Returns the number of (encrypted) bytes sent.
"""
if not self._is_handshake_completed:
raise IOError('SSL Handshake was not completed; cannot send data.')
# Pass the cleartext data to the SSL engine
self._ssl.write(data)
# Recover the corresponding encrypted data
final_length = self._flush_ssl_engine()
return final_length
def _flush_ssl_engine(self):
# type: () -> int
length_to_read = self._network_bio.pending()
final_length = length_to_read
while length_to_read:
encrypted_data = self._network_bio.read(length_to_read)
# Send the encrypted data to the peer
self._sock.send(encrypted_data)
length_to_read = self._network_bio.pending()
final_length += length_to_read
return final_length
def shutdown(self):
# type: () -> None
self._is_handshake_completed = False
try:
self._ssl.shutdown()
self._flush_ssl_engine()
except OpenSSLError as e:
# Ignore "uninitialized" exception
if 'SSL_shutdown:uninitialized' not in str(e) and 'shutdown while in init' not in str(e):
raise
def _set_verify(self, verify_mode):
# type: (int) -> None
"""Set the OpenSSL verify mode. Private method because it should be set via the constructor.
"""
self._ssl._set_verify(verify_mode)
def set_tlsext_host_name(self, name_indication):
# type: (str) -> None
"""Set the hostname within the Server Name Indication extension in the client SSL Hello.
"""
self._ssl.set_tlsext_host_name(name_indication)
def get_peer_certificate(self):
# type: () -> Optional[X509Certificate]
_x509 = self._ssl.get_peer_certificate()
if _x509:
return X509Certificate(_x509)
else:
return None
def get_peer_cert_chain(self):
# type: () -> List[X509Certificate]
"""See the OpenSSL documentation for differences between get_peer_cert_chain() and get_peer_certificate().
https://www.openssl.org/docs/ssl/SSL_get_peer_cert_chain.html
"""
x509_list = self._ssl.get_peer_cert_chain()
final_list = []
if x509_list:
for x509_cert in x509_list:
final_list.append(X509Certificate(x509_cert))
return final_list
def set_cipher_list(self, cipher_list):
# type: (str) -> None
self._ssl.set_cipher_list(cipher_list)
def get_cipher_list(self):
# type: () -> List[str]
return self._ssl.get_cipher_list()
def get_current_cipher_name(self):
# type: () -> str
return self._ssl.get_cipher_name()
def get_current_cipher_bits(self):
# type: () -> int
return self._ssl.get_cipher_bits()
def _use_private_key(self, client_certchain_file, client_key_file, client_key_type, client_key_password):
# type: (str, str, int, str) -> None
"""The certificate chain file must be in PEM format. Private method because it should be set via the
constructor.
"""
self._ssl_ctx.use_certificate_chain_file(client_certchain_file)
if isinstance(client_key_password, basestring):
self._ssl_ctx.set_private_key_password(client_key_password)
else:
raise TypeError('client_key_password is not a string')
try:
self._ssl_ctx.use_PrivateKey_file(client_key_file, client_key_type)
except OpenSSLError as e:
if 'bad password read' in str(e) or 'bad decrypt' in str(e):
raise ValueError('Invalid Private Key')
else:
raise
self._ssl_ctx.check_private_key()
def get_certificate_chain_verify_result(self):
# type: () -> Tuple[int, str]
verify_result = self._ssl.get_verify_result()
verify_result_str = X509.verify_cert_error_string(verify_result)
return verify_result, verify_result_str
def set_tlsext_status_ocsp(self):
# type: () -> None
"""Enable the OCSP Stapling extension.
"""
self._ssl.set_tlsext_status_type(TLSEXT_STATUSTYPE_ocsp)
def get_tlsext_status_ocsp_resp(self):
# type: () -> Optional[OcspResponse]
"""Retrieve the server's OCSP Stapling status.
"""
ocsp_response = self._ssl.get_tlsext_status_ocsp_resp()
if ocsp_response:
return OcspResponse(ocsp_response)
else:
return None
def get_client_CA_list(self):
# type: () -> List[str]
if not self._client_CA_list:
self._client_CA_list = self._ssl.get_client_CA_list()
return self._client_CA_list
def set_mode(self, mode):
# type: (int) -> None
self._ssl.set_mode(mode)
