# 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 re 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 _SSLContext, SSLError from _ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED from _ssl import OP_ALL, OP_NO_SSLv2, OP_NO_SSLv3, OP_NO_TLSv1 from _ssl import RAND_status, RAND_egd, RAND_add, RAND_bytes, RAND_pseudo_bytes 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 HAS_SNI from _ssl import (PROTOCOL_SSLv3, PROTOCOL_SSLv23, PROTOCOL_TLSv1) from _ssl import _OPENSSL_API_VERSION _PROTOCOL_NAMES = { PROTOCOL_TLSv1: "TLSv1", PROTOCOL_SSLv23: "SSLv23", PROTOCOL_SSLv3: "SSLv3", } try: from _ssl import PROTOCOL_SSLv2 except ImportError: pass else: _PROTOCOL_NAMES[PROTOCOL_SSLv2] = "SSLv2" from socket import getnameinfo as _getnameinfo from socket import error as socket_error from socket import socket, AF_INET, SOCK_STREAM, create_connection import base64 # for DER-to-PEM translation import traceback import errno class CertificateError(ValueError): pass def _dnsname_to_pat(dn): pats = [] for frag in dn.split(r'.'): if frag == '*': # When '*' is a fragment by itself, it matches a non-empty dotless # fragment. pats.append('[^.]+') else: # Otherwise, '*' matches any dotless fragment. frag = re.escape(frag) pats.append(frag.replace(r'\*', '[^.]*')) return re.compile(r'\A' + r'\.'.join(pats) + r'\Z', re.IGNORECASE) def match_hostname(cert, hostname): """Verify that *cert* (in decoded format as returned by SSLSocket.getpeercert()) matches the *hostname*. RFC 2818 rules are mostly followed, but IP addresses are not accepted for *hostname*. CertificateError is raised on failure. On success, the function returns nothing. """ if not cert: raise ValueError("empty or no certificate") dnsnames = [] san = cert.get('subjectAltName', ()) for key, value in san: if key == 'DNS': if _dnsname_to_pat(value).match(hostname): return dnsnames.append(value) if not dnsnames: # The subject is only checked when there is no dNSName entry # in subjectAltName for sub in cert.get('subject', ()): for key, value in sub: # XXX according to RFC 2818, the most specific Common Name # must be used. if key == 'commonName': if _dnsname_to_pat(value).match(hostname): return dnsnames.append(value) if len(dnsnames) > 1: raise CertificateError("hostname %r " "doesn't match either of %s" % (hostname, ', '.join(map(repr, dnsnames)))) elif len(dnsnames) == 1: raise CertificateError("hostname %r " "doesn't match %r" % (hostname, dnsnames[0])) else: raise CertificateError("no appropriate commonName or " "subjectAltName fields were found") class SSLContext(_SSLContext): """An SSLContext holds various SSL-related configuration options and data, such as certificates and possibly a private key.""" __slots__ = ('protocol',) def __new__(cls, protocol, *args, **kwargs): return _SSLContext.__new__(cls, protocol) def __init__(self, protocol): self.protocol = protocol def wrap_socket(self, sock, server_side=False, do_handshake_on_connect=True, suppress_ragged_eofs=True, server_hostname=None): return SSLSocket(sock=sock, server_side=server_side, do_handshake_on_connect=do_handshake_on_connect, suppress_ragged_eofs=suppress_ragged_eofs, server_hostname=server_hostname, _context=self) 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=None, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version=PROTOCOL_SSLv23, ca_certs=None, do_handshake_on_connect=True, family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None, suppress_ragged_eofs=True, ciphers=None, server_hostname=None, _context=None): if _context: self.context = _context else: if server_side and not certfile: raise ValueError("certfile must be specified for server-side " "operations") if keyfile and not certfile: raise ValueError("certfile must be specified") if certfile and not keyfile: keyfile = certfile self.context = SSLContext(ssl_version) self.context.verify_mode = cert_reqs if ca_certs: self.context.load_verify_locations(ca_certs) if certfile: self.context.load_cert_chain(certfile, keyfile) if ciphers: self.context.set_ciphers(ciphers) self.keyfile = keyfile self.certfile = certfile self.cert_reqs = cert_reqs self.ssl_version = ssl_version self.ca_certs = ca_certs self.ciphers = ciphers if server_side and server_hostname: raise ValueError("server_hostname can only be specified " "in client mode") self.server_side = server_side self.server_hostname = server_hostname self.do_handshake_on_connect = do_handshake_on_connect self.suppress_ragged_eofs = suppress_ragged_eofs connected = False if sock is not None: socket.__init__(self, family=sock.family, type=sock.type, proto=sock.proto, fileno=sock.fileno()) self.settimeout(sock.gettimeout()) # see if it's connected try: sock.getpeername() except socket_error as e: if e.errno != errno.ENOTCONN: raise else: connected = True sock.detach() elif fileno is not None: socket.__init__(self, fileno=fileno) else: socket.__init__(self, family=family, type=type, proto=proto) self._closed = False self._sslobj = None self._connected = connected if connected: # create the SSL object try: self._sslobj = self.context._wrap_socket(self, server_side, server_hostname) if do_handshake_on_connect: timeout = self.gettimeout() if timeout == 0.0: # non-blocking raise ValueError("do_handshake_on_connect should not be specified for non-blocking sockets") self.do_handshake() except socket_error as x: self.close() raise x def dup(self): raise NotImplemented("Can't dup() %s instances" % self.__class__.__name__) def _checkClosed(self, msg=None): # raise an exception here if you wish to check for spurious closes pass def read(self, len=0, buffer=None): """Read up to LEN bytes and return them. Return zero-length string on EOF.""" self._checkClosed() try: if buffer is not None: v = self._sslobj.read(len, buffer) else: v = self._sslobj.read(len or 1024) return v except SSLError as x: if x.args[0] == SSL_ERROR_EOF and self.suppress_ragged_eofs: if buffer is not None: return 0 else: return b'' else: raise def write(self, data): """Write DATA to the underlying SSL channel. Returns number of bytes of DATA actually transmitted.""" self._checkClosed() 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.""" self._checkClosed() return self._sslobj.peer_certificate(binary_form) def cipher(self): self._checkClosed() if not self._sslobj: return None else: return self._sslobj.cipher() def send(self, data, flags=0): self._checkClosed() 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 as 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 socket.send(self, data, flags) def sendto(self, data, flags_or_addr, addr=None): self._checkClosed() if self._sslobj: raise ValueError("sendto not allowed on instances of %s" % self.__class__) elif addr is None: return socket.sendto(self, data, flags_or_addr) else: return socket.sendto(self, data, flags_or_addr, addr) def sendall(self, data, flags=0): self._checkClosed() 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): self._checkClosed() 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 socket.recv(self, buflen, flags) def recv_into(self, buffer, nbytes=None, flags=0): self._checkClosed() 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__) return self.read(nbytes, buffer) else: return socket.recv_into(self, buffer, nbytes, flags) def recvfrom(self, buflen=1024, flags=0): self._checkClosed() if self._sslobj: raise ValueError("recvfrom not allowed on instances of %s" % self.__class__) else: return socket.recvfrom(self, buflen, flags) def recvfrom_into(self, buffer, nbytes=None, flags=0): self._checkClosed() if self._sslobj: raise ValueError("recvfrom_into not allowed on instances of %s" % self.__class__) else: return socket.recvfrom_into(self, buffer, nbytes, flags) def pending(self): self._checkClosed() if self._sslobj: return self._sslobj.pending() else: return 0 def shutdown(self, how): self._checkClosed() self._sslobj = None socket.shutdown(self, how) 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 _real_close(self): self._sslobj = None # self._closed = True socket._real_close(self) def do_handshake(self, block=False): """Perform a TLS/SSL handshake.""" timeout = self.gettimeout() try: if timeout == 0.0 and block: self.settimeout(None) self._sslobj.do_handshake() finally: self.settimeout(timeout) def _real_connect(self, addr, connect_ex): if self.server_side: raise ValueError("can't connect in server-side mode") # 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 = self.context._wrap_socket(self, False, self.server_hostname) try: if connect_ex: 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) return (SSLSocket(sock=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), addr) def __del__(self): # sys.stderr.write("__del__ on %s\n" % repr(self)) self._real_close() 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=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.""" f = str(base64.standard_b64encode(der_cert_bytes), 'ASCII', 'strict') return (PEM_HEADER + '\n' + textwrap.fill(f, 64) + '\n' + 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.decodebytes(d.encode('ASCII', 'strict')) 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 = create_connection(addr) s = wrap_socket(s, ssl_version=ssl_version, cert_reqs=cert_reqs, ca_certs=ca_certs) 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, '')