# Copyright (C) 2009 Internet Systems Consortium. # # Permission to use, copy, modify, and distribute this software for any # purpose with or without fee is hereby granted, provided that the above # copyright notice and this permission notice appear in all copies. # # THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM # DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL # INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, # INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING # FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, # NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION # WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. # # Client-side functionality for configuration and commands # # It keeps a cc-channel session with the configuration manager daemon, # and handles configuration updates and direct commands # modeled after ccsession.h/cc 'protocol' changes here need to be # made there as well """Classes and functions for handling configuration and commands This module provides the ModuleCCSession and UIModuleCCSession classes, as well as a set of utility functions to create and parse messages related to commands and configuration Modules should use the ModuleCCSession class to connect to the configuration manager, and receive updates and commands from other modules. Configuration user interfaces should use the UIModuleCCSession to connect to b10-cmdctl, and receive and send configuration and commands through that to the configuration manager. """ from isc.cc import Session from isc.config.config_data import ConfigData, MultiConfigData, BIND10_CONFIG_DATA_VERSION import isc class ModuleCCSessionError(Exception): pass def parse_answer(msg): """Returns a tuple (rcode, value), where value depends on the command that was called. If rcode != 0, value is a string containing an error message""" if type(msg) != dict: raise ModuleCCSessionError("Answer message is not a dict: " + str(msg)) if 'result' not in msg: raise ModuleCCSessionError("answer message does not contain 'result' element") elif type(msg['result']) != list: raise ModuleCCSessionError("wrong result type in answer message") elif len(msg['result']) < 1: raise ModuleCCSessionError("empty result list in answer message") elif type(msg['result'][0]) != int: raise ModuleCCSessionError("wrong rcode type in answer message") else: if len(msg['result']) > 1: if (msg['result'][0] != 0 and type(msg['result'][1]) != str): raise ModuleCCSessionError("rcode in answer message is non-zero, value is not a string") return msg['result'][0], msg['result'][1] else: return msg['result'][0], None def create_answer(rcode, arg = None): """Creates an answer packet for config&commands. rcode must be an integer. If rcode == 0, arg is an optional value that depends on what the command or option was. If rcode != 0, arg must be a string containing an error message""" if type(rcode) != int: raise ModuleCCSessionError("rcode in create_answer() must be an integer") if rcode != 0 and type(arg) != str: raise ModuleCCSessionError("arg in create_answer for rcode != 0 must be a string describing the error") if arg != None: return { 'result': [ rcode, arg ] } else: return { 'result': [ rcode ] } # 'fixed' commands """Fixed names for command and configuration messages""" COMMAND_CONFIG_UPDATE = "config_update" COMMAND_MODULE_SPECIFICATION_UPDATE = "module_specification_update" COMMAND_GET_COMMANDS_SPEC = "get_commands_spec" COMMAND_GET_CONFIG = "get_config" COMMAND_SET_CONFIG = "set_config" COMMAND_GET_MODULE_SPEC = "get_module_spec" COMMAND_MODULE_SPEC = "module_spec" COMMAND_SHUTDOWN = "shutdown" def parse_command(msg): """Parses what may be a command message. If it looks like one, the function returns (command, value) where command is a string. If it is not, this function returns None, None""" if type(msg) == dict and len(msg.items()) == 1: cmd, value = msg.popitem() if cmd == "command" and type(value) == list: if len(value) == 1 and type(value[0]) == str: return value[0], None elif len(value) > 1 and type(value[0]) == str: return value[0], value[1] return None, None def create_command(command_name, params = None): """Creates a module command message with the given command name (as specified in the module's specification, and an optional params object""" # TODO: validate_command with spec if type(command_name) != str: raise ModuleCCSessionError("command in create_command() not a string") cmd = [ command_name ] if params: cmd.append(params) msg = { 'command': cmd } return msg class ModuleCCSession(ConfigData): """This class maintains a connection to the command channel, as well as configuration options for modules. The module provides a specification file that contains the module name, configuration options, and commands. It also gives the ModuleCCSession two callback functions, one to call when there is a direct command to the module, and one to update the configuration run-time. These callbacks are called when 'check_command' is called on the ModuleCCSession""" def __init__(self, spec_file_name, config_handler, command_handler, cc_session = None): """Initialize a ModuleCCSession. This does *NOT* send the specification and request the configuration yet. Use start() for that once the ModuleCCSession has been initialized. specfile_name is the path to the specification file config_handler and command_handler are callback functions, see set_config_handler and set_command_handler for more information on their signatures.""" module_spec = isc.config.module_spec_from_file(spec_file_name) ConfigData.__init__(self, module_spec) self._module_name = module_spec.get_module_name() self.set_config_handler(config_handler) self.set_command_handler(command_handler) if not cc_session: self._session = Session() else: self._session = cc_session self._session.group_subscribe(self._module_name, "*") self._remote_module_configs = {} def __del__(self): # If the CC Session obejct has been closed, it returns # immediately. if self._session._closed: return self._session.group_unsubscribe(self._module_name, "*") for module_name in self._remote_module_configs: self._session.group_unsubscribe(module_name) def start(self): """Send the specification for this module to the configuration manager, and request the current non-default configuration. The config_handler will be called with that configuration""" self.__send_spec() self.__request_config() def get_socket(self): """Returns the socket from the command channel session. This should *only* be used for select() loops to see if there is anything on the channel. If that loop is not completely time-critical, it is strongly recommended to only use check_command(), and not look at the socket at all.""" return self._session._socket def close(self): """Close the session to the command channel""" self._session.close() def check_command(self, nonblock=True): """Check whether there is a command or configuration update on the channel. This function does a read on the cc session, and returns nothing. It calls check_command_without_recvmsg() to parse the received message. If nonblock is True, it just checks if there's a command and does nothing if there isn't. If nonblock is False, it waits until it arrives. It temporarily sets timeout to infinity, because commands may not come in arbitrary long time.""" timeout_orig = self._session.get_timeout() self._session.set_timeout(0) try: msg, env = self._session.group_recvmsg(nonblock) finally: self._session.set_timeout(timeout_orig) self.check_command_without_recvmsg(msg, env) def check_command_without_recvmsg(self, msg, env): """Parse the given message to see if there is a command or a configuration update. Calls the corresponding handler functions if present. Responds on the channel if the handler returns a message.""" # should we default to an answer? success-by-default? unhandled error? if msg is not None and not 'result' in msg: answer = None try: module_name = env['group'] cmd, arg = isc.config.ccsession.parse_command(msg) if cmd == COMMAND_CONFIG_UPDATE: new_config = arg # If the target channel was not this module # it might be in the remote_module_configs if module_name != self._module_name: if module_name in self._remote_module_configs: # no checking for validity, that's up to the # module itself. newc = self._remote_module_configs[module_name].get_local_config() isc.cc.data.merge(newc, new_config) self._remote_module_configs[module_name].set_local_config(newc) # For other modules, we're not supposed to answer return # ok, so apparently this update is for us. errors = [] if not self._config_handler: answer = create_answer(2, self._module_name + " has no config handler") elif not self.get_module_spec().validate_config(False, new_config, errors): answer = create_answer(1, ", ".join(errors)) else: isc.cc.data.remove_identical(new_config, self.get_local_config()) answer = self._config_handler(new_config) rcode, val = parse_answer(answer) if rcode == 0: newc = self.get_local_config() isc.cc.data.merge(newc, new_config) self.set_local_config(newc) else: # ignore commands for 'remote' modules if module_name == self._module_name: if self._command_handler: answer = self._command_handler(cmd, arg) else: answer = create_answer(2, self._module_name + " has no command handler") except Exception as exc: answer = create_answer(1, str(exc)) if answer: self._session.group_reply(env, answer) def set_config_handler(self, config_handler): """Set the config handler for this module. The handler is a function that takes the full configuration and handles it. It should return an answer created with create_answer()""" self._config_handler = config_handler # should we run this right now since we've changed the handler? def set_command_handler(self, command_handler): """Set the command handler for this module. The handler is a function that takes a command as defined in the .spec file and return an answer created with create_answer()""" self._command_handler = command_handler def add_remote_config(self, spec_file_name): """Gives access to the configuration of a different module. These remote module options can at this moment only be accessed through get_remote_config_value(). This function also subscribes to the channel of the remote module name to receive the relevant updates. It is not possible to specify your own handler for this right now. start() must have been called on this CCSession prior to the call to this method. Returns the name of the module.""" module_spec = isc.config.module_spec_from_file(spec_file_name) module_cfg = ConfigData(module_spec) module_name = module_spec.get_module_name() self._session.group_subscribe(module_name); # Get the current config for that module now seq = self._session.group_sendmsg(create_command(COMMAND_GET_CONFIG, { "module_name": module_name }), "ConfigManager") try: answer, env = self._session.group_recvmsg(False, seq) except isc.cc.SessionTimeout: raise ModuleCCSessionError("No answer from ConfigManager when " "asking about Remote module " + module_name) if answer: rcode, value = parse_answer(answer) if rcode == 0: if value != None and module_spec.validate_config(False, value): module_cfg.set_local_config(value); # all done, add it self._remote_module_configs[module_name] = module_cfg return module_name def remove_remote_config(self, module_name): """Removes the remote configuration access for this module""" if module_name in self._remote_module_configs: self._session.group_unsubscribe(module_name) del self._remote_module_configs[module_name] def get_remote_config_value(self, module_name, identifier): """Returns the current setting for the given identifier at the given module. If the module has not been added with add_remote_config, a ModuleCCSessionError is raised""" if module_name in self._remote_module_configs: return self._remote_module_configs[module_name].get_value(identifier) else: raise ModuleCCSessionError("Remote module " + module_name + " not found") def __send_spec(self): """Sends the data specification to the configuration manager""" msg = create_command(COMMAND_MODULE_SPEC, self.get_module_spec().get_full_spec()) seq = self._session.group_sendmsg(msg, "ConfigManager") try: answer, env = self._session.group_recvmsg(False, seq) except isc.cc.SessionTimeout: # TODO: log an error? pass def __request_config(self): """Asks the configuration manager for the current configuration, and call the config handler if set. Raises a ModuleCCSessionError if there is no answer from the configuration manager""" seq = self._session.group_sendmsg(create_command(COMMAND_GET_CONFIG, { "module_name": self._module_name }), "ConfigManager") try: answer, env = self._session.group_recvmsg(False, seq) if answer: rcode, value = parse_answer(answer) if rcode == 0: errors = [] if value != None: if self.get_module_spec().validate_config(False, value, errors): self.set_local_config(value); if self._config_handler: self._config_handler(value) else: raise ModuleCCSessionError( "Wrong data in configuration: " + " ".join(errors)) else: # log error print("[" + self._module_name + "] Error requesting configuration: " + value) else: raise ModuleCCSessionError("No answer from configuration manager") except isc.cc.SessionTimeout: raise ModuleCCSessionError("CC Session timeout waiting for configuration manager") class UIModuleCCSession(MultiConfigData): """This class is used in a configuration user interface. It contains specific functions for getting, displaying, and sending configuration settings through the b10-cmdctl module.""" def __init__(self, conn): """Initialize a UIModuleCCSession. The conn object that is passed must have send_GET and send_POST functions""" MultiConfigData.__init__(self) self._conn = conn self.request_specifications() self.request_current_config() def request_specifications(self): """Request the module specifications from b10-cmdctl""" # this step should be unnecessary but is the current way cmdctl returns stuff # so changes are needed there to make this clean (we need a command to simply get the # full specs for everything, including commands etc, not separate gets for that) specs = self._conn.send_GET('/module_spec') for module in specs.keys(): self.set_specification(isc.config.ModuleSpec(specs[module])) def update_specs_and_config(self): self.request_specifications(); self.request_current_config(); def request_current_config(self): """Requests the current configuration from the configuration manager through b10-cmdctl, and stores those as CURRENT""" config = self._conn.send_GET('/config_data') if 'version' not in config or config['version'] != BIND10_CONFIG_DATA_VERSION: raise ModuleCCSessionError("Bad config version") self._set_current_config(config) def add_value(self, identifier, value_str = None): """Add a value to a configuration list. Raises a DataTypeError if the value does not conform to the list_item_spec field of the module config data specification. If value_str is not given, we add the default as specified by the .spec file.""" module_spec = self.find_spec_part(identifier) if (type(module_spec) != dict or "list_item_spec" not in module_spec): raise isc.cc.data.DataNotFoundError(str(identifier) + " is not a list") cur_list, status = self.get_value(identifier) if not cur_list: cur_list = [] # Hmm. Do we need to check for duplicates? value = None if value_str is not None: value = isc.cc.data.parse_value_str(value_str) else: if "item_default" in module_spec["list_item_spec"]: value = module_spec["list_item_spec"]["item_default"] if value is None: raise isc.cc.data.DataNotFoundError("No value given and no default for " + str(identifier)) if value not in cur_list: cur_list.append(value) self.set_value(identifier, cur_list) def remove_value(self, identifier, value_str): """Remove a value from a configuration list. The value string must be a string representation of the full item. Raises a DataTypeError if the value at the identifier is not a list, or if the given value_str does not match the list_item_spec """ module_spec = self.find_spec_part(identifier) if (type(module_spec) != dict or "list_item_spec" not in module_spec): raise isc.cc.data.DataNotFoundError(str(identifier) + " is not a list") if value_str is None: # we are directly removing an list index id, list_indices = isc.cc.data.split_identifier_list_indices(identifier) if list_indices is None: raise DataTypeError("identifier in remove_value() does not contain a list index, and no value to remove") else: self.set_value(identifier, None) else: value = isc.cc.data.parse_value_str(value_str) isc.config.config_data.check_type(module_spec, [value]) cur_list, status = self.get_value(identifier) #if not cur_list: # cur_list = isc.cc.data.find_no_exc(self.config.data, identifier) if not cur_list: cur_list = [] if value in cur_list: cur_list.remove(value) self.set_value(identifier, cur_list) def commit(self): """Commit all local changes, send them through b10-cmdctl to the configuration manager""" if self.get_local_changes(): response = self._conn.send_POST('/ConfigManager/set_config', [ self.get_local_changes() ]) answer = isc.cc.data.parse_value_str(response.read().decode()) # answer is either an empty dict (on success), or one # containing errors if answer == {}: self.request_current_config() self.clear_local_changes() elif "error" in answer: print("Error: " + answer["error"]) print("Configuration not committed") else: raise ModuleCCSessionError("Unknown format of answer in commit(): " + str(answer))