228 lines
8.1 KiB
Python
228 lines
8.1 KiB
Python
#!/usr/bin/python
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from transport import BaseTransport
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from transport import MSG_SERVICE_REQUEST, MSG_SERVICE_ACCEPT, MSG_USERAUTH_REQUEST, MSG_USERAUTH_FAILURE, \
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MSG_USERAUTH_SUCCESS, MSG_USERAUTH_BANNER
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from message import Message
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from secsh import SSHException
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from logging import DEBUG, INFO, WARNING, ERROR, CRITICAL
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DISCONNECT_SERVICE_NOT_AVAILABLE, DISCONNECT_AUTH_CANCELLED_BY_USER, \
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DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE = 7, 13, 14
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class Transport(BaseTransport):
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"BaseTransport with the auth framework hooked up"
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AUTH_SUCCESSFUL, AUTH_PARTIALLY_SUCCESSFUL, AUTH_FAILED = range(3)
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def __init__(self, sock):
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BaseTransport.__init__(self, sock)
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self.auth_event = None
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# for server mode:
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self.auth_username = None
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self.auth_fail_count = 0
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self.auth_complete = 0
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def request_auth(self):
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m = Message()
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m.add_byte(chr(MSG_SERVICE_REQUEST))
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m.add_string('ssh-userauth')
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self.send_message(m)
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def auth_key(self, username, key, event):
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if (not self.active) or (not self.initial_kex_done):
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# we should never try to send the password unless we're on a secure link
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raise SSHException('No existing session')
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try:
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self.lock.acquire()
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self.auth_event = event
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self.auth_method = 'publickey'
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self.username = username
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self.private_key = key
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self.request_auth()
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finally:
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self.lock.release()
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def auth_password(self, username, password, event):
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'authenticate using a password; event is triggered on success or fail'
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if (not self.active) or (not self.initial_kex_done):
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# we should never try to send the password unless we're on a secure link
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raise SSHException('No existing session')
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try:
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self.lock.acquire()
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self.auth_event = event
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self.auth_method = 'password'
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self.username = username
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self.password = password
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self.request_auth()
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finally:
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self.lock.release()
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def disconnect_service_not_available(self):
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m = Message()
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m.add_byte(chr(MSG_DISCONNECT))
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m.add_int(DISCONNECT_SERVICE_NOT_AVAILABLE)
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m.add_string('Service not available')
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m.add_string('en')
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self.send_message(m)
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self.close()
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def disconnect_no_more_auth(self):
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m = Message()
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m.add_byte(chr(MSG_DISCONNECT))
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m.add_int(DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE)
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m.add_string('No more auth methods available')
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m.add_string('en')
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self.send_message(m)
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self.close()
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def parse_service_request(self, m):
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service = m.get_string()
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if self.server_mode and (service == 'ssh-userauth'):
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# accepted
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m = Message()
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m.add_byte(chr(MSG_SERVICE_ACCEPT))
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m.add_string(service)
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self.send_message(m)
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return
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# dunno this one
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self.disconnect_service_not_available()
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def parse_service_accept(self, m):
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service = m.get_string()
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if service == 'ssh-userauth':
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self.log(DEBUG, 'userauth is OK')
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m = Message()
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m.add_byte(chr(MSG_USERAUTH_REQUEST))
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m.add_string(self.username)
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m.add_string('ssh-connection')
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m.add_string(self.auth_method)
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if self.auth_method == 'password':
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m.add_boolean(0)
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m.add_string(self.password.encode('UTF-8'))
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elif self.auth_method == 'publickey':
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m.add_boolean(1)
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m.add_string(self.private_key.get_name())
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m.add_string(str(self.private_key))
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m.add_string(self.private_key.sign_ssh_session(self.randpool, self.H, self.username))
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else:
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raise SSHException('Unknown auth method "%s"' % self.auth_method)
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self.send_message(m)
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else:
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self.log(DEBUG, 'Service request "%s" accepted (?)' % service)
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def get_allowed_auths(self, username):
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"override me!"
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return 'password'
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def check_auth_none(self, username):
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"override me! return int ==> auth status"
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return self.AUTH_FAILED
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def check_auth_password(self, username, password):
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"override me! return int ==> auth status"
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return self.AUTH_FAILED
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def check_auth_publickey(self, username, key):
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"override me! return int ==> auth status"
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return self.AUTH_FAILED
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def parse_userauth_request(self, m):
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if not self.server_mode:
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# er, uh... what?
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m = Message()
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m.add_byte(chr(MSG_USERAUTH_FAILURE))
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m.add_string('none')
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m.add_boolean(0)
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self.send_message(m)
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return
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if self.auth_complete:
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# ignore
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return
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username = m.get_string()
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service = m.get_string()
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method = m.get_string()
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self.log(DEBUG, 'Auth request (type=%s) service=%s, username=%s' % (method, service, username))
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if service != 'ssh-connection':
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self.disconnect_service_not_available()
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return
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if (self.auth_username is not None) and (self.auth_username != username):
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self.log(DEBUG, 'Auth rejected because the client attempted to change username in mid-flight')
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self.disconnect_no_more_auth()
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return
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if method == 'none':
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result = self.check_auth_none(username)
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elif method == 'password':
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changereq = m.get_boolean()
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password = m.get_string().decode('UTF-8')
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if changereq:
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# always treated as failure, since we don't support changing passwords, but collect
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# the list of valid auth types from the callback anyway
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self.log(DEBUG, 'Auth request to change passwords (rejected)')
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newpassword = m.get_string().decode('UTF-8')
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result = self.AUTH_FAILED
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else:
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result = self.check_auth_password(username, password)
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elif method == 'publickey':
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# FIXME
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result = self.check_auth_none(username)
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else:
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result = self.check_auth_none(username)
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# okay, send result
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m = Message()
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if result == self.AUTH_SUCCESSFUL:
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self.log(DEBUG, 'Auth granted.')
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m.add_byte(chr(MSG_USERAUTH_SUCCESS))
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self.auth_complete = 1
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else:
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self.log(DEBUG, 'Auth rejected.')
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m.add_byte(chr(MSG_USERAUTH_FAILURE))
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m.add_string(self.get_allowed_auths(username))
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if result == self.AUTH_PARTIALLY_SUCCESSFUL:
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m.add_boolean(1)
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else:
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m.add_boolean(0)
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self.auth_fail_count += 1
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self.send_message(m)
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if self.auth_fail_count >= 10:
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self.disconnect_no_more_auth()
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def parse_userauth_success(self, m):
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self.log(INFO, 'Authentication successful!')
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self.authenticated = 1
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if self.auth_event != None:
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self.auth_event.set()
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def parse_userauth_failure(self, m):
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authlist = m.get_list()
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partial = m.get_boolean()
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if partial:
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self.log(INFO, 'Authentication continues...')
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self.log(DEBUG, 'Methods: ' + str(partial))
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# FIXME - do something
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pass
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self.log(INFO, 'Authentication failed.')
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self.authenticated = 0
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self.close()
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if self.auth_event != None:
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self.auth_event.set()
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def parse_userauth_banner(self, m):
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banner = m.get_string()
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lang = m.get_string()
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self.log(INFO, 'Auth banner: ' + banner)
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# who cares.
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handler_table = BaseTransport.handler_table.copy()
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handler_table.update({
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MSG_SERVICE_REQUEST: parse_service_request,
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MSG_SERVICE_ACCEPT: parse_service_accept,
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MSG_USERAUTH_REQUEST: parse_userauth_request,
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MSG_USERAUTH_SUCCESS: parse_userauth_success,
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MSG_USERAUTH_FAILURE: parse_userauth_failure,
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MSG_USERAUTH_BANNER: parse_userauth_banner,
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})
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