commando: reckless? Try going commando!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

commando/README.md

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+# Commando plugin
+
+This plugin allows other nodes to send your node commands, and allows you
+to send them to other nodes.  The nodes must be authorized, and must be
+directly connected.
+
+Motto: Reckless?  Try going commando!
+
+## Installation
+
+For general plugin installation instructions see the repos main
+[README.md](https://github.com/lightningd/plugins/blob/master/README.md#Installation)
+
+## Options:
+
+Each of these can be specified more than once:
+
+* --commando-reader: a node id which can execute `list` and `get` commands
+* --commando-writer: a node id which can execute any commands.
+
+## Example Usage
+
+$ l1-cli plugin start commando.py commando_reader=0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518
+$ l2-cli plugin start commando.py
+$ l2-cli commando 022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59 stop
+
+

commando/commando.py

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+#!/usr/bin/env python3
+"""Commando is a plugin to allow one node to control another.  You use
+"commando" to send commands, and the 'commando-writer' and
+'commando-reader' to allow nodes to send you commands.
+
+The formats are:
+
+type:4C4F - execute this command
+type:594B - reply (with more coming)
+type:594D - last reply
+
+Each one is an 8 byte id (to link replies to command), followed by JSON.
+"""
+from pyln.client import Plugin, RpcError
+import json
+import textwrap
+import random
+
+plugin = Plugin()
+
+# "YOLO"!
+COMMANDO_CMD = 0x4c4f
+
+# Replies are split across multiple CONTINUES, then TERM.
+COMMANDO_REPLY_CONTINUES = 0x594b
+COMMANDO_REPLY_TERM = 0x594d
+
+
+class CommandResponse:
+    def __init__(self, req):
+        self.buf = bytes()
+        self.req = req
+
+
+def split_cmd(cmdstr):
+    """Interprets JSON and method and params"""
+    cmd = json.loads(cmdstr)
+
+    return cmd['method'], cmd.get('params')
+
+
+def send_msg(plugin, peer_id, msgtype, idnum, contents):
+    """Messages are form [8-byte-id][data]"""
+    msg = (msgtype.to_bytes(2, 'big')
+           + idnum.to_bytes(8, 'big')
+           + bytes(contents, encoding='utf8'))
+    plugin.rpc.call(plugin.msgcmd, {'node_id': peer_id, 'msg': msg.hex()})
+
+
+def send_result(plugin, peer_id, idnum, res):
+    # We can only send 64k in a message.
+    parts = textwrap.wrap(json.dumps(res), 65000)
+    for p in parts[:-1]:
+        send_msg(plugin, peer_id, COMMANDO_REPLY_CONTINUES, idnum, p)
+
+    send_msg(plugin, peer_id, COMMANDO_REPLY_TERM, idnum, parts[-1])
+
+
+def exec_command(plugin, peer_id, idnum, method, params):
+    """Run an arbitrary command and message back the result"""
+    try:
+        res = {'result': plugin.rpc.call(method, params)}
+    except RpcError as e:
+        res = {'error': e.error}
+
+    send_result(plugin, peer_id, idnum, res)
+
+
+def exec_read_command(plugin, peer_id, idnum, method, params):
+    """Run a list or get command and message back the result"""
+    if method.startswith('list') or method.startswith('get'):
+        exec_command(plugin, peer_id, idnum, method, params)
+    else:
+        send_result(plugin, peer_id, idnum, {'error': "Not permitted"})
+
+
+@plugin.hook('custommsg')
+def on_custommsg(peer_id, payload, plugin, **kwargs):
+    pbytes = bytes.fromhex(payload)
+    mtype = int.from_bytes(pbytes[:2], "big")
+    idnum = int.from_bytes(pbytes[2:10], "big")
+    data = pbytes[10:]
+
+    if mtype == COMMANDO_CMD:
+        if peer_id in plugin.writers:
+            exec_command(plugin, peer_id, idnum, *split_cmd(data))
+        elif peer_id in plugin.readers:
+            exec_read_command(plugin, peer_id, idnum, *split_cmd(data))
+    elif mtype == COMMANDO_REPLY_CONTINUES:
+        if idnum in plugin.reqs:
+            plugin.reqs[idnum].buf += data
+    elif mtype == COMMANDO_REPLY_TERM:
+        if idnum in plugin.reqs:
+            plugin.reqs[idnum].buf += data
+            finished = plugin.reqs[idnum]
+            del plugin.reqs[idnum]
+
+            try:
+                ret = json.loads(finished.buf.decode())
+            except Exception as e:
+                # Bad response
+                finished.req.set_exception(e)
+                return {'result': 'continue'}
+
+            if 'error' in ret:
+                # Pass through error
+                finished.req.set_exception(RpcError('commando', {},
+                                                    ret['error']))
+            else:
+                # Pass through result
+                finished.req.set_result(ret['result'])
+    return {'result': 'continue'}
+
+
+@plugin.async_method("commando")
+def commando(plugin, request, peer_id, method, params=None):
+    """Send a command to node_id, and wait for a response"""
+    res = {'method': method}
+    if params:
+        res['params'] = params
+
+    while True:
+        idnum = random.randint(0, 2**64)
+        if idnum not in plugin.reqs:
+            break
+
+    plugin.reqs[idnum] = CommandResponse(request)
+    send_msg(plugin, peer_id, COMMANDO_CMD, idnum, json.dumps(res))
+
+
+@plugin.init()
+def init(options, configuration, plugin):
+    plugin.writers = options['commando_writer']
+    plugin.readers = options['commando_reader']
+    plugin.reqs = {}
+
+    # dev-sendcustommsg was renamed to sendcustommsg for 0.10.1
+    try:
+        plugin.rpc.help('sendcustommsg')
+        plugin.msgcmd = 'sendcustommsg'
+    except RpcError:
+        plugin.msgcmd = 'dev-sendcustommsg'
+
+    plugin.log("Initialized with readers {}, writers {}"
+               .format(plugin.readers, plugin.writers))
+
+
+plugin.add_option('commando_writer',
+                  description="What nodeid can do all commands?",
+                  default=[],
+                  multi=True)
+plugin.add_option('commando_reader',
+                  description="What nodeid can do list/get commands?",
+                  default=[],
+                  multi=True)
+plugin.run()

commando/test_commando.py

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+import os
+from pyln.testing.fixtures import *  # noqa: F401,F403
+from pyln.client import Millisatoshi, RpcError
+
+plugin_path = os.path.join(os.path.dirname(__file__), "commando.py")
+
+
+def test_commando(node_factory):
+    l1, l2 = node_factory.line_graph(2, fundchannel=False)
+
+    l1.rpc.plugin_start(plugin_path, commando_reader=l2.info['id'])
+    l2.rpc.plugin_start(plugin_path)
+
+    # This works
+    res = l2.rpc.call(method='commando',
+                      payload={'peer_id': l1.info['id'],
+                               'method': 'listpeers'})
+    assert len(res['peers']) == 1
+    assert res['peers'][0]['id'] == l2.info['id']
+
+    res = l2.rpc.call(method='commando',
+                      payload={'peer_id': l1.info['id'],
+                               'method': 'listpeers',
+                               'params': {'id': l2.info['id']}})
+    assert len(res['peers']) == 1
+    assert res['peers'][0]['id'] == l2.info['id']
+
+    # This fails
+    with pytest.raises(RpcError, match='Not permitted'):
+        l2.rpc.call(method='commando',
+                    payload={'peer_id': l1.info['id'],
+                             'method': 'withdraw'})
+
+    # As a writer, anything goes.
+    l1.rpc.plugin_stop(plugin_path)
+    l1.rpc.plugin_start(plugin_path, commando_writer=l2.info['id'])
+
+    with pytest.raises(RpcError, match='missing required parameter'):
+        l2.rpc.call(method='commando',
+                    payload={'peer_id': l1.info['id'],
+                             'method': 'withdraw'})
+
+    ret = l2.rpc.call(method='commando',
+                      payload={'peer_id': l1.info['id'],
+                               'method': 'ping',
+                               'params': {'id': l2.info['id']}})
+    assert 'totlen' in ret
+
+    # Now, this will go over a single message!
+    ret = l2.rpc.call(method='commando',
+                      payload={'peer_id': l1.info['id'],
+                               'method': 'getlog',
+                               'params': {'level': 'io'}})
+
+    assert len(json.dumps(ret)) > 65535