from collections import OrderedDict from enum import Enum from lightning import LightningRpc, Millisatoshi from threading import RLock import inspect import json import os import re import sys import traceback class MethodType(Enum): RPCMETHOD = 0 HOOK = 1 class RequestState(Enum): PENDING = 'pending' FINISHED = 'finished' FAILED = 'failed' class Method(object): """Description of methods that are registered with the plugin. These can be one of the following: - RPC exposed by RPC passthrough - HOOK registered to be called synchronously by lightningd """ def __init__(self, name, func, mtype=MethodType.RPCMETHOD): self.name = name self.func = func self.mtype = mtype self.background = False class Request(dict): """A request object that wraps params and allows async return """ def __init__(self, plugin, req_id, method, params, background=False): self.method = method self.params = params self.background = background self.plugin = plugin self.state = RequestState.PENDING self.id = req_id def getattr(self, key): if key == "params": return self.params elif key == "id": return self.id elif key == "method": return self.method def set_result(self, result): if self.state != RequestState.PENDING: raise ValueError( "Cannot set the result of a request that is not pending, " "current state is {state}".format(self.state)) self.result = result self._write_result({ 'jsonrpc': '2.0', 'id': self.id, 'result': self.result }) def set_exception(self, exc): if self.state != RequestState.PENDING: raise ValueError( "Cannot set the exception of a request that is not pending, " "current state is {state}".format(self.state)) self.exc = exc self._write_result({ 'jsonrpc': '2.0', 'id': self.id, "error": "Error while processing {method}: {exc}".format( method=self.method, exc=repr(exc) ), }) def _write_result(self, result): self.plugin._write_locked(result) class Plugin(object): """Controls interactions with lightningd, and bundles functionality. The Plugin class serves two purposes: it collects RPC methods and options, and offers a control loop that dispatches incoming RPC calls and hooks. """ def __init__(self, stdout=None, stdin=None, autopatch=True): self.methods = {'init': Method('init', self._init, MethodType.RPCMETHOD)} self.options = {} # A dict from topics to handler functions self.subscriptions = {} if not stdout: self.stdout = sys.stdout if not stdin: self.stdin = sys.stdin if os.getenv('LIGHTNINGD_PLUGIN') and autopatch: monkey_patch(self, stdout=True, stderr=True) self.add_method("getmanifest", self._getmanifest, background=False) self.rpc_filename = None self.lightning_dir = None self.rpc = None self.child_init = None self.write_lock = RLock() def add_method(self, name, func, background=False): """Add a plugin method to the dispatch table. The function will be expected at call time (see `_dispatch`) and the parameters from the JSON-RPC call will be mapped to the function arguments. In addition to the parameters passed from the JSON-RPC call we add a few that may be useful: - `plugin`: gets a reference to this plugin. - `request`: gets a reference to the raw request as a dict. This corresponds to the JSON-RPC message that is being dispatched. Notice that due to the python binding logic we may be mapping the arguments wrongly if we inject the plugin and/or request in combination with positional binding. To prevent issues the plugin and request argument should always be the last two arguments and have a default on None. The `background` argument can be used to specify whether the method is going to return a result that should be sent back to the lightning daemon (`background=False`) or whether the method will return without sending back a result. In the latter case the method MUST use `request.set_result` or `result.set_exception` to return a result or raise an exception for the call. """ if name in self.methods: raise ValueError( "Name {} is already bound to a method.".format(name) ) # Register the function with the name method = Method(name, func, MethodType.RPCMETHOD) method.background = background self.methods[name] = method def add_subscription(self, topic, func): """Add a subscription to our list of subscriptions. A subscription is an association between a topic and a handler function. Adding a subscription means that we will automatically subscribe to events from that topic with `lightningd` and, upon receiving a matching notification, we will call the associated handler. Notice that in order for the automatic subscriptions to work, the handlers need to be registered before we send our manifest, hence before `Plugin.run` is called. """ if topic in self.subscriptions: raise ValueError( "Topic {} already has a handler".format(topic) ) self.subscriptions[topic] = func def subscribe(self, topic): """Function decorator to register a notification handler. """ def decorator(f): self.add_subscription(topic, f) return f return decorator def add_option(self, name, default, description): """Add an option that we'd like to register with lightningd. Needs to be called before `Plugin.run`, otherwise we might not end up getting it set. """ if name in self.options: raise ValueError( "Name {} is already used by another option".format(name) ) self.options[name] = { 'name': name, 'default': default, 'description': description, 'type': 'string', 'value': None, } def get_option(self, name): if name not in self.options: raise ValueError("No option with name {} registered".format(name)) if self.options[name]['value'] is not None: return self.options[name]['value'] else: return self.options[name]['default'] def async_method(self, method_name): """Decorator to add an async plugin method to the dispatch table. Internally uses add_method. """ def decorator(f): self.add_method(method_name, f, background=True) return f return decorator def method(self, method_name): """Decorator to add a plugin method to the dispatch table. Internally uses add_method. """ def decorator(f): self.add_method(method_name, f, background=False) return f return decorator def add_hook(self, name, func, background=False): """Register a hook that is called synchronously by lightningd on events """ if name in self.methods: raise ValueError( "Method {} was already registered".format(name, self.methods[name]) ) method = Method(name, func, MethodType.HOOK) method.background = background self.methods[name] = method def hook(self, method_name): """Decorator to add a plugin hook to the dispatch table. Internally uses add_hook. """ def decorator(f): self.add_hook(method_name, f, background=False) return f return decorator def async_hook(self, method_name): """Decorator to add an async plugin hook to the dispatch table. Internally uses add_hook. """ def decorator(f): self.add_hook(method_name, f, background=True) return f return decorator def init(self, *args, **kwargs): """Decorator to add a function called after plugin initialization """ def decorator(f): if self.child_init is not None: raise ValueError('The @plugin.init decorator should only be used once') self.child_init = f return f return decorator def _exec_func(self, func, request): params = request.params sig = inspect.signature(func) arguments = OrderedDict() for name, value in sig.parameters.items(): arguments[name] = inspect._empty # Fill in any injected parameters if 'plugin' in arguments: arguments['plugin'] = self if 'request' in arguments: arguments['request'] = request args = [] kwargs = {} # Now zip the provided arguments and the prefilled a together if isinstance(params, dict): for k, v in params.items(): if k in arguments: # Explicitly (try to) interpret as Millisatoshi if annotated if func.__annotations__.get(k) == Millisatoshi: arguments[k] = Millisatoshi(v) else: arguments[k] = v else: kwargs[k] = v else: pos = 0 for k, v in arguments.items(): # Skip already assigned args and special catch-all args if v is not inspect._empty or k in ['args', 'kwargs']: continue if pos < len(params): # Apply positional args if we have them if func.__annotations__.get(k) == Millisatoshi: arguments[k] = Millisatoshi(params[pos]) else: arguments[k] = params[pos] elif sig.parameters[k].default is inspect.Signature.empty: # This is a positional arg with no value passed raise TypeError("Missing required parameter: %s" % sig.parameters[k]) else: # For the remainder apply default args arguments[k] = sig.parameters[k].default pos += 1 if len(arguments) < len(params): args = params[len(arguments):] if 'kwargs' in arguments: arguments['kwargs'] = kwargs elif len(kwargs) > 0: raise TypeError("Extra arguments given: {kwargs}".format(kwargs=kwargs)) if 'args' in arguments: arguments['args'] = args elif len(args) > 0: raise TypeError("Extra arguments given: {args}".format(args=args)) missing = [k for k, v in arguments.items() if v is inspect._empty] if missing: raise TypeError("Missing positional arguments ({given} given, " "expected {expected}): {missing}".format( missing=", ".join(missing), given=len(arguments) - len(missing), expected=len(arguments) )) ba = sig.bind(**arguments) ba.apply_defaults() return func(*ba.args, **ba.kwargs) def _dispatch_request(self, request): name = request.method if name not in self.methods: raise ValueError("No method {} found.".format(name)) method = self.methods[name] request.background = method.background try: result = self._exec_func(method.func, request) if not method.background: # Only if this is not an async (background) call do we need to # return the result, otherwise the callee will eventually need # to call request.set_result or request.set_exception to # return a result or raise an exception. request.set_result(result) except Exception as e: request.set_exception(e) self.log(traceback.format_exc()) def _dispatch_notification(self, request): if request.method not in self.subscriptions: raise ValueError("No subscription for {name} found.".format( name=request.method)) func = self.subscriptions[request.method] try: self._exec_func(func, request) except Exception: self.log(traceback.format_exc()) def _write_locked(self, obj): s = json.dumps(obj, cls=LightningRpc.LightningJSONEncoder) + "\n\n" with self.write_lock: self.stdout.write(s) self.stdout.flush() def notify(self, method, params): payload = { 'jsonrpc': '2.0', 'method': method, 'params': params, } self._write_locked(payload) def log(self, message, level='info'): # Split the log into multiple lines and print them # individually. Makes tracebacks much easier to read. for line in message.split('\n'): self.notify('log', {'level': level, 'message': line}) def _parse_request(self, jsrequest): request = Request( plugin=self, req_id=jsrequest.get('id', None), method=jsrequest['method'], params=jsrequest['params'], background=False, ) return request def _multi_dispatch(self, msgs): """We received a couple of messages, now try to dispatch them all. Returns the last partial message that was not complete yet. """ for payload in msgs[:-1]: # Note that we use function annotations to do Millisatoshi conversions # in _exec_func, so we don't use LightningJSONDecoder here. request = self._parse_request(json.loads(payload)) # If this has an 'id'-field, it's a request and returns a # result. Otherwise it's a notification and it doesn't # return anything. if request.id is not None: self._dispatch_request(request) else: self._dispatch_notification(request) return msgs[-1] def run(self): partial = "" for l in self.stdin: partial += l msgs = partial.split('\n\n') if len(msgs) < 2: continue partial = self._multi_dispatch(msgs) def _getmanifest(self, **kwargs): methods = [] hooks = [] for method in self.methods.values(): # Skip the builtin ones, they don't get reported if method.name in ['getmanifest', 'init']: continue if method.mtype == MethodType.HOOK: hooks.append(method.name) continue doc = inspect.getdoc(method.func) if not doc: self.log( 'RPC method \'{}\' does not have a docstring.'.format(method.name) ) doc = "Undocumented RPC method from a plugin." doc = re.sub('\n+', ' ', doc) # Handles out-of-order use of parameters like: # def hello_obfus(arg1, arg2, plugin, thing3, request=None, thing5='at', thing6=21) argspec = inspect.getfullargspec(method.func) defaults = argspec.defaults num_defaults = len(defaults) if defaults else 0 start_kwargs_idx = len(argspec.args) - num_defaults args = [] for idx, arg in enumerate(argspec.args): if arg in ('plugin', 'request'): continue # Positional arg if idx < start_kwargs_idx: args.append("%s" % arg) # Keyword arg else: args.append("[%s]" % arg) methods.append({ 'name': method.name, 'usage': " ".join(args), 'description': doc }) return { 'options': list(self.options.values()), 'rpcmethods': methods, 'subscriptions': list(self.subscriptions.keys()), 'hooks': hooks, } def _init(self, options, configuration, request): self.rpc_filename = configuration['rpc-file'] self.lightning_dir = configuration['lightning-dir'] path = os.path.join(self.lightning_dir, self.rpc_filename) self.rpc = LightningRpc(path) for name, value in options.items(): self.options[name]['value'] = value # Dispatch the plugin's init handler if any if self.child_init: return self._exec_func(self.child_init, request) return None class PluginStream(object): """Sink that turns everything that is written to it into a notification. """ def __init__(self, plugin, level="info"): self.plugin = plugin self.level = level self.buff = '' def write(self, payload): self.buff += payload if len(payload) > 0 and payload[-1] == '\n': self.flush() def flush(self): lines = self.buff.split('\n') if len(lines) < 2: return for l in lines[:-1]: self.plugin.log(l, self.level) # lines[-1] is either an empty string or a partial line self.buff = lines[-1] def monkey_patch(plugin, stdout=True, stderr=False): """Monkey patch stderr and stdout so we use notifications instead. A plugin commonly communicates with lightningd over its stdout and stdin filedescriptor, so if we use them in some other way (printing, logging, ...) we're breaking our communication channel. This function monkey patches these streams in the `sys` module to be redirected to a `PluginStream` which wraps anything that would get written to these streams into valid log notifications that can be interpreted and printed by `lightningd`. """ if stdout: setattr(sys, "stdout", PluginStream(plugin, level="info")) if stderr: setattr(sys, "stderr", PluginStream(plugin, level="warn"))