| # Wrapper module for _ssl, providing some additional facilities |
| # implemented in Python. Written by Bill Janssen. |
| |
| """\ |
| This module provides some more Pythonic support for SSL. |
| |
| Object types: |
| |
| SSLSocket -- subtype of socket.socket which does SSL over the socket |
| |
| Exceptions: |
| |
| SSLError -- exception raised for I/O errors |
| |
| Functions: |
| |
| cert_time_to_seconds -- convert time string used for certificate |
| notBefore and notAfter functions to integer |
| seconds past the Epoch (the time values |
| returned from time.time()) |
| |
| fetch_server_certificate (HOST, PORT) -- fetch the certificate provided |
| by the server running on HOST at port PORT. No |
| validation of the certificate is performed. |
| |
| Integer constants: |
| |
| SSL_ERROR_ZERO_RETURN |
| SSL_ERROR_WANT_READ |
| SSL_ERROR_WANT_WRITE |
| SSL_ERROR_WANT_X509_LOOKUP |
| SSL_ERROR_SYSCALL |
| SSL_ERROR_SSL |
| SSL_ERROR_WANT_CONNECT |
| |
| SSL_ERROR_EOF |
| SSL_ERROR_INVALID_ERROR_CODE |
| |
| The following group define certificate requirements that one side is |
| allowing/requiring from the other side: |
| |
| CERT_NONE - no certificates from the other side are required (or will |
| be looked at if provided) |
| CERT_OPTIONAL - certificates are not required, but if provided will be |
| validated, and if validation fails, the connection will |
| also fail |
| CERT_REQUIRED - certificates are required, and will be validated, and |
| if validation fails, the connection will also fail |
| |
| The following constants identify various SSL protocol variants: |
| |
| PROTOCOL_SSLv2 |
| PROTOCOL_SSLv3 |
| PROTOCOL_SSLv23 |
| PROTOCOL_TLSv1 |
| """ |
| |
| import textwrap |
| |
| import _ssl # if we can't import it, let the error propagate |
| |
| from _ssl import OPENSSL_VERSION_NUMBER, OPENSSL_VERSION_INFO, OPENSSL_VERSION |
| from _ssl import SSLError |
| from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED |
| from _ssl import RAND_status, RAND_egd, RAND_add |
| from _ssl import \ |
| SSL_ERROR_ZERO_RETURN, \ |
| SSL_ERROR_WANT_READ, \ |
| SSL_ERROR_WANT_WRITE, \ |
| SSL_ERROR_WANT_X509_LOOKUP, \ |
| SSL_ERROR_SYSCALL, \ |
| SSL_ERROR_SSL, \ |
| SSL_ERROR_WANT_CONNECT, \ |
| SSL_ERROR_EOF, \ |
| SSL_ERROR_INVALID_ERROR_CODE |
| from _ssl import PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1 |
| _PROTOCOL_NAMES = { |
| PROTOCOL_TLSv1: "TLSv1", |
| PROTOCOL_SSLv23: "SSLv23", |
| PROTOCOL_SSLv3: "SSLv3", |
| } |
| try: |
| from _ssl import PROTOCOL_SSLv2 |
| _SSLv2_IF_EXISTS = PROTOCOL_SSLv2 |
| except ImportError: |
| _SSLv2_IF_EXISTS = None |
| else: |
| _PROTOCOL_NAMES[PROTOCOL_SSLv2] = "SSLv2" |
| |
| from socket import socket, _fileobject, _delegate_methods, error as socket_error |
| from socket import getnameinfo as _getnameinfo |
| import base64 # for DER-to-PEM translation |
| import errno |
| |
| # Disable weak or insecure ciphers by default |
| # (OpenSSL's default setting is 'DEFAULT:!aNULL:!eNULL') |
| _DEFAULT_CIPHERS = 'DEFAULT:!aNULL:!eNULL:!LOW:!EXPORT:!SSLv2' |
| |
| |
| class SSLSocket(socket): |
| |
| """This class implements a subtype of socket.socket that wraps |
| the underlying OS socket in an SSL context when necessary, and |
| provides read and write methods over that channel.""" |
| |
| def __init__(self, sock, keyfile=None, certfile=None, |
| server_side=False, cert_reqs=CERT_NONE, |
| ssl_version=PROTOCOL_SSLv23, ca_certs=None, |
| do_handshake_on_connect=True, |
| suppress_ragged_eofs=True, ciphers=None): |
| socket.__init__(self, _sock=sock._sock) |
| # The initializer for socket overrides the methods send(), recv(), etc. |
| # in the instancce, which we don't need -- but we want to provide the |
| # methods defined in SSLSocket. |
| for attr in _delegate_methods: |
| try: |
| delattr(self, attr) |
| except AttributeError: |
| pass |
| |
| if ciphers is None and ssl_version != _SSLv2_IF_EXISTS: |
| ciphers = _DEFAULT_CIPHERS |
| |
| if certfile and not keyfile: |
| keyfile = certfile |
| # see if it's connected |
| try: |
| socket.getpeername(self) |
| except socket_error, e: |
| if e.errno != errno.ENOTCONN: |
| raise |
| # no, no connection yet |
| self._connected = False |
| self._sslobj = None |
| else: |
| # yes, create the SSL object |
| self._connected = True |
| self._sslobj = _ssl.sslwrap(self._sock, server_side, |
| keyfile, certfile, |
| cert_reqs, ssl_version, ca_certs, |
| ciphers) |
| if do_handshake_on_connect: |
| self.do_handshake() |
| self.keyfile = keyfile |
| self.certfile = certfile |
| self.cert_reqs = cert_reqs |
| self.ssl_version = ssl_version |
| self.ca_certs = ca_certs |
| self.ciphers = ciphers |
| self.do_handshake_on_connect = do_handshake_on_connect |
| self.suppress_ragged_eofs = suppress_ragged_eofs |
| self._makefile_refs = 0 |
| |
| def read(self, len=1024): |
| |
| """Read up to LEN bytes and return them. |
| Return zero-length string on EOF.""" |
| |
| try: |
| return self._sslobj.read(len) |
| except SSLError, x: |
| if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs: |
| return '' |
| else: |
| raise |
| |
| def write(self, data): |
| |
| """Write DATA to the underlying SSL channel. Returns |
| number of bytes of DATA actually transmitted.""" |
| |
| return self._sslobj.write(data) |
| |
| def getpeercert(self, binary_form=False): |
| |
| """Returns a formatted version of the data in the |
| certificate provided by the other end of the SSL channel. |
| Return None if no certificate was provided, {} if a |
| certificate was provided, but not validated.""" |
| |
| return self._sslobj.peer_certificate(binary_form) |
| |
| def cipher(self): |
| |
| if not self._sslobj: |
| return None |
| else: |
| return self._sslobj.cipher() |
| |
| def send(self, data, flags=0): |
| if self._sslobj: |
| if flags != 0: |
| raise ValueError( |
| "non-zero flags not allowed in calls to send() on %s" % |
| self.__class__) |
| while True: |
| try: |
| v = self._sslobj.write(data) |
| except SSLError, x: |
| if x.args[0] == SSL_ERROR_WANT_READ: |
| return 0 |
| elif x.args[0] == SSL_ERROR_WANT_WRITE: |
| return 0 |
| else: |
| raise |
| else: |
| return v |
| else: |
| return self._sock.send(data, flags) |
| |
| def sendto(self, data, flags_or_addr, addr=None): |
| if self._sslobj: |
| raise ValueError("sendto not allowed on instances of %s" % |
| self.__class__) |
| elif addr is None: |
| return self._sock.sendto(data, flags_or_addr) |
| else: |
| return self._sock.sendto(data, flags_or_addr, addr) |
| |
| def sendall(self, data, flags=0): |
| if self._sslobj: |
| if flags != 0: |
| raise ValueError( |
| "non-zero flags not allowed in calls to sendall() on %s" % |
| self.__class__) |
| amount = len(data) |
| count = 0 |
| while (count < amount): |
| v = self.send(data[count:]) |
| count += v |
| return amount |
| else: |
| return socket.sendall(self, data, flags) |
| |
| def recv(self, buflen=1024, flags=0): |
| if self._sslobj: |
| if flags != 0: |
| raise ValueError( |
| "non-zero flags not allowed in calls to recv() on %s" % |
| self.__class__) |
| return self.read(buflen) |
| else: |
| return self._sock.recv(buflen, flags) |
| |
| def recv_into(self, buffer, nbytes=None, flags=0): |
| if buffer and (nbytes is None): |
| nbytes = len(buffer) |
| elif nbytes is None: |
| nbytes = 1024 |
| if self._sslobj: |
| if flags != 0: |
| raise ValueError( |
| "non-zero flags not allowed in calls to recv_into() on %s" % |
| self.__class__) |
| tmp_buffer = self.read(nbytes) |
| v = len(tmp_buffer) |
| buffer[:v] = tmp_buffer |
| return v |
| else: |
| return self._sock.recv_into(buffer, nbytes, flags) |
| |
| def recvfrom(self, buflen=1024, flags=0): |
| if self._sslobj: |
| raise ValueError("recvfrom not allowed on instances of %s" % |
| self.__class__) |
| else: |
| return self._sock.recvfrom(buflen, flags) |
| |
| def recvfrom_into(self, buffer, nbytes=None, flags=0): |
| if self._sslobj: |
| raise ValueError("recvfrom_into not allowed on instances of %s" % |
| self.__class__) |
| else: |
| return self._sock.recvfrom_into(buffer, nbytes, flags) |
| |
| def pending(self): |
| if self._sslobj: |
| return self._sslobj.pending() |
| else: |
| return 0 |
| |
| def unwrap(self): |
| if self._sslobj: |
| s = self._sslobj.shutdown() |
| self._sslobj = None |
| return s |
| else: |
| raise ValueError("No SSL wrapper around " + str(self)) |
| |
| def shutdown(self, how): |
| self._sslobj = None |
| socket.shutdown(self, how) |
| |
| def close(self): |
| if self._makefile_refs < 1: |
| self._sslobj = None |
| socket.close(self) |
| else: |
| self._makefile_refs -= 1 |
| |
| def do_handshake(self): |
| |
| """Perform a TLS/SSL handshake.""" |
| |
| self._sslobj.do_handshake() |
| |
| def _real_connect(self, addr, return_errno): |
| # Here we assume that the socket is client-side, and not |
| # connected at the time of the call. We connect it, then wrap it. |
| if self._connected: |
| raise ValueError("attempt to connect already-connected SSLSocket!") |
| self._sslobj = _ssl.sslwrap(self._sock, False, self.keyfile, self.certfile, |
| self.cert_reqs, self.ssl_version, |
| self.ca_certs, self.ciphers) |
| try: |
| if return_errno: |
| rc = socket.connect_ex(self, addr) |
| else: |
| rc = None |
| socket.connect(self, addr) |
| if not rc: |
| if self.do_handshake_on_connect: |
| self.do_handshake() |
| self._connected = True |
| return rc |
| except socket_error: |
| self._sslobj = None |
| raise |
| |
| def connect(self, addr): |
| """Connects to remote ADDR, and then wraps the connection in |
| an SSL channel.""" |
| self._real_connect(addr, False) |
| |
| def connect_ex(self, addr): |
| """Connects to remote ADDR, and then wraps the connection in |
| an SSL channel.""" |
| return self._real_connect(addr, True) |
| |
| def accept(self): |
| |
| """Accepts a new connection from a remote client, and returns |
| a tuple containing that new connection wrapped with a server-side |
| SSL channel, and the address of the remote client.""" |
| |
| newsock, addr = socket.accept(self) |
| try: |
| return (SSLSocket(newsock, |
| keyfile=self.keyfile, |
| certfile=self.certfile, |
| server_side=True, |
| cert_reqs=self.cert_reqs, |
| ssl_version=self.ssl_version, |
| ca_certs=self.ca_certs, |
| ciphers=self.ciphers, |
| do_handshake_on_connect=self.do_handshake_on_connect, |
| suppress_ragged_eofs=self.suppress_ragged_eofs), |
| addr) |
| except socket_error as e: |
| newsock.close() |
| raise e |
| |
| def makefile(self, mode='r', bufsize=-1): |
| |
| """Make and return a file-like object that |
| works with the SSL connection. Just use the code |
| from the socket module.""" |
| |
| self._makefile_refs += 1 |
| # close=True so as to decrement the reference count when done with |
| # the file-like object. |
| return _fileobject(self, mode, bufsize, close=True) |
| |
| |
| |
| def wrap_socket(sock, keyfile=None, certfile=None, |
| server_side=False, cert_reqs=CERT_NONE, |
| ssl_version=PROTOCOL_SSLv23, ca_certs=None, |
| do_handshake_on_connect=True, |
| suppress_ragged_eofs=True, ciphers=None): |
| |
| return SSLSocket(sock, keyfile=keyfile, certfile=certfile, |
| server_side=server_side, cert_reqs=cert_reqs, |
| ssl_version=ssl_version, ca_certs=ca_certs, |
| do_handshake_on_connect=do_handshake_on_connect, |
| suppress_ragged_eofs=suppress_ragged_eofs, |
| ciphers=ciphers) |
| |
| |
| # some utility functions |
| |
| def cert_time_to_seconds(cert_time): |
| |
| """Takes a date-time string in standard ASN1_print form |
| ("MON DAY 24HOUR:MINUTE:SEC YEAR TIMEZONE") and return |
| a Python time value in seconds past the epoch.""" |
| |
| import time |
| return time.mktime(time.strptime(cert_time, "%b %d %H:%M:%S %Y GMT")) |
| |
| PEM_HEADER = "-----BEGIN CERTIFICATE-----" |
| PEM_FOOTER = "-----END CERTIFICATE-----" |
| |
| def DER_cert_to_PEM_cert(der_cert_bytes): |
| |
| """Takes a certificate in binary DER format and returns the |
| PEM version of it as a string.""" |
| |
| if hasattr(base64, 'standard_b64encode'): |
| # preferred because older API gets line-length wrong |
| f = base64.standard_b64encode(der_cert_bytes) |
| return (PEM_HEADER + '\n' + |
| textwrap.fill(f, 64) + '\n' + |
| PEM_FOOTER + '\n') |
| else: |
| return (PEM_HEADER + '\n' + |
| base64.encodestring(der_cert_bytes) + |
| PEM_FOOTER + '\n') |
| |
| def PEM_cert_to_DER_cert(pem_cert_string): |
| |
| """Takes a certificate in ASCII PEM format and returns the |
| DER-encoded version of it as a byte sequence""" |
| |
| if not pem_cert_string.startswith(PEM_HEADER): |
| raise ValueError("Invalid PEM encoding; must start with %s" |
| % PEM_HEADER) |
| if not pem_cert_string.strip().endswith(PEM_FOOTER): |
| raise ValueError("Invalid PEM encoding; must end with %s" |
| % PEM_FOOTER) |
| d = pem_cert_string.strip()[len(PEM_HEADER):-len(PEM_FOOTER)] |
| return base64.decodestring(d) |
| |
| def get_server_certificate(addr, ssl_version=PROTOCOL_SSLv3, ca_certs=None): |
| |
| """Retrieve the certificate from the server at the specified address, |
| and return it as a PEM-encoded string. |
| If 'ca_certs' is specified, validate the server cert against it. |
| If 'ssl_version' is specified, use it in the connection attempt.""" |
| |
| host, port = addr |
| if (ca_certs is not None): |
| cert_reqs = CERT_REQUIRED |
| else: |
| cert_reqs = CERT_NONE |
| s = wrap_socket(socket(), ssl_version=ssl_version, |
| cert_reqs=cert_reqs, ca_certs=ca_certs) |
| s.connect(addr) |
| dercert = s.getpeercert(True) |
| s.close() |
| return DER_cert_to_PEM_cert(dercert) |
| |
| def get_protocol_name(protocol_code): |
| return _PROTOCOL_NAMES.get(protocol_code, '<unknown>') |
| |
| |
| # a replacement for the old socket.ssl function |
| |
| def sslwrap_simple(sock, keyfile=None, certfile=None): |
| |
| """A replacement for the old socket.ssl function. Designed |
| for compability with Python 2.5 and earlier. Will disappear in |
| Python 3.0.""" |
| |
| if hasattr(sock, "_sock"): |
| sock = sock._sock |
| |
| ssl_sock = _ssl.sslwrap(sock, 0, keyfile, certfile, CERT_NONE, |
| PROTOCOL_SSLv23, None) |
| try: |
| sock.getpeername() |
| except socket_error: |
| # no, no connection yet |
| pass |
| else: |
| # yes, do the handshake |
| ssl_sock.do_handshake() |
| |
| return ssl_sock |
