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IRCNetwork: split SSL connection setup into separate functions
* _make_ssl_context(): returns the SSLContext to use on he network (with options set) * _setup_ssl(): sets up TLS by loading certfile / keyfile and calling wrap_socket() * _verify_ssl(): implements certificate fingerprint verification, raising TLSVerificationError (a new subclass of ConnectionError) if this fails This is a prerequisite for #592.
This commit is contained in:
James Lu
parent
8386edc6d5
commit
579b5ce93f
144
classes.py
144
classes.py
@ -1525,6 +1525,9 @@ class PyLinkNetworkCoreWithUtils(PyLinkNetworkCore):
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# This is protocol specific, so stub it here in the base class.
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raise NotImplementedError
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class TLSValidationError(ConnectionError):
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"""Exception raised when additional TLS verifications fail."""
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class IRCNetwork(PyLinkNetworkCoreWithUtils):
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S2S_BUFSIZE = 510
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@ -1572,6 +1575,73 @@ class IRCNetwork(PyLinkNetworkCoreWithUtils):
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else:
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log.error(*args, **kwargs)
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def _make_ssl_context(self):
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"""
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Returns a ssl.SSLContext instance appropriate for this connection.
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"""
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context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
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# Disable SSLv2 and SSLv3 - these are insecure
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context.options |= ssl.OP_NO_SSLv2
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context.options |= ssl.OP_NO_SSLv3
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return context
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def _setup_ssl(self):
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"""
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Initializes SSL/TLS for this network.
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"""
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log.info('(%s) Using TLS/SSL for this connection...', self.name)
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certfile = self.serverdata.get('ssl_certfile')
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keyfile = self.serverdata.get('ssl_keyfile')
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context = self._make_ssl_context()
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# Cert and key files are optional, load them if specified.
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if certfile and keyfile:
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try:
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context.load_cert_chain(certfile, keyfile)
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except OSError:
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log.exception('(%s) Caught OSError trying to initialize the SSL connection; '
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'are "ssl_certfile" and "ssl_keyfile" set correctly?',
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self.name)
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raise
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self._socket = context.wrap_socket(self._socket)
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def _verify_ssl(self):
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"""
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Implements additional SSL/TLS verification (so far, only certificate fingerprints if enabled).
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"""
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peercert = self._socket.getpeercert(binary_form=True)
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# Hash type is configurable using the ssl_fingerprint_type
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# value, and defaults to sha256.
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hashtype = self.serverdata.get('ssl_fingerprint_type', 'sha256').lower()
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try:
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hashfunc = getattr(hashlib, hashtype)
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except AttributeError:
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raise conf.ConfigurationError('Unsupported or invalid TLS/SSL certificate fingerprint type %r',
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hashtype)
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else:
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fp = hashfunc(peercert).hexdigest()
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expected_fp = self.serverdata.get('ssl_fingerprint')
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if expected_fp:
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if fp != expected_fp:
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# SSL Fingerprint doesn't match; break.
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raise TLSValidationError('Uplink TLS/SSL certificate fingerprint (%s) does not '
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'match the one configured (%s: %s)' % (expected_fp, hashtype, fp))
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else:
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log.info('(%s) Uplink TLS/SSL certificate fingerprint '
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'(%s) verified: %r', self.name, hashtype, fp)
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else:
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log.info('(%s) Uplink\'s TLS/SSL certificate fingerprint (%s) '
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'is %r. You can enhance the security of your '
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'link by specifying this in a "ssl_fingerprint"'
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' option in your server block.', self.name,
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hashtype, fp)
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def _connect(self):
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"""
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Connects to the network.
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@ -1580,7 +1650,6 @@ class IRCNetwork(PyLinkNetworkCoreWithUtils):
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ip = self.serverdata["ip"]
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port = self.serverdata["port"]
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checks_ok = True
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try:
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# Set the socket type (IPv6 or IPv4).
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stype = socket.AF_INET6 if self.serverdata.get("ipv6") else socket.AF_INET
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@ -1600,28 +1669,7 @@ class IRCNetwork(PyLinkNetworkCoreWithUtils):
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# Enable SSL if set to do so.
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self.ssl = self.serverdata.get('ssl')
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if self.ssl:
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log.info('(%s) Attempting SSL for this connection...', self.name)
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certfile = self.serverdata.get('ssl_certfile')
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keyfile = self.serverdata.get('ssl_keyfile')
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context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
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# Disable SSLv2 and SSLv3 - these are insecure
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context.options |= ssl.OP_NO_SSLv2
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context.options |= ssl.OP_NO_SSLv3
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# Cert and key files are optional, load them if specified.
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if certfile and keyfile:
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try:
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context.load_cert_chain(certfile, keyfile)
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except OSError:
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log.exception('(%s) Caught OSError trying to '
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'initialize the SSL connection; '
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'are "ssl_certfile" and '
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'"ssl_keyfile" set correctly?',
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self.name)
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checks_ok = False
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self._socket = context.wrap_socket(self._socket)
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self._setup_ssl()
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log.info("Connecting to network %r on %s:%s", self.name, ip, port)
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@ -1653,48 +1701,8 @@ class IRCNetwork(PyLinkNetworkCoreWithUtils):
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self._selector_key = selectdriver.register(self)
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# If SSL was enabled, optionally verify the certificate
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# fingerprint for some added security. I don't bother to check
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# the entire certificate for validity, since most IRC networks
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# self-sign their certificates anyways.
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if self.ssl and checks_ok:
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peercert = self._socket.getpeercert(binary_form=True)
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# Hash type is configurable using the ssl_fingerprint_type
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# value, and defaults to sha256.
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hashtype = self.serverdata.get('ssl_fingerprint_type', 'sha256').lower()
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try:
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hashfunc = getattr(hashlib, hashtype)
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except AttributeError:
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log.error('(%s) Unsupported SSL certificate fingerprint type %r given, disconnecting...',
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self.name, hashtype)
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checks_ok = False
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else:
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fp = hashfunc(peercert).hexdigest()
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expected_fp = self.serverdata.get('ssl_fingerprint')
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if expected_fp and checks_ok:
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if fp != expected_fp:
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# SSL Fingerprint doesn't match; break.
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log.error('(%s) Uplink\'s SSL certificate '
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'fingerprint (%s) does not match the '
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'one configured: expected %r, got %r; '
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'disconnecting...', self.name, hashtype,
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expected_fp, fp)
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checks_ok = False
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else:
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log.info('(%s) Uplink SSL certificate fingerprint '
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'(%s) verified: %r', self.name, hashtype,
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fp)
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else:
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log.info('(%s) Uplink\'s SSL certificate fingerprint (%s) '
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'is %r. You can enhance the security of your '
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'link by specifying this in a "ssl_fingerprint"'
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' option in your server block.', self.name,
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hashtype, fp)
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if checks_ok:
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if self.ssl:
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self._verify_ssl()
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self._queue_thread = threading.Thread(name="Queue thread for %s" % self.name,
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target=self._process_queue, daemon=True)
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@ -1716,11 +1724,7 @@ class IRCNetwork(PyLinkNetworkCoreWithUtils):
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self._schedule_ping()
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log.info('(%s) Server ready; listening for data.', self.name)
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self.autoconnect_active_multiplier = 1 # Reset any extra autoconnect delays
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else: # Configuration error :(
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log.error('(%s) A configuration error was encountered '
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'trying to set up this connection. Please check'
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' your configuration file and try again.',
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self.name)
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# _run_irc() or the protocol module it called raised an exception, meaning we've disconnected!
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# Note: socket.error, ConnectionError, IOError, etc. are included in OSError since Python 3.3,
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# so we don't need to explicitly catch them here.
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