plugins/clnrest: disable ourselves unless rest-port is set.

This mirrors grpc's behavior, and avoids listening on ports without
explicit user permission.

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

plugins/clnrest/README.md

@@ -6,11 +6,15 @@ CLNRest is a lightweight Python-based core lightning plugin that transforms RPC
 
 Install required packages with `pip install json5 flask flask_restx gunicorn pyln-client` or `pip install -r requirements.txt`.
 
+Note: if you have the older c-lightning-rest plugin, you can use `disable-plugin clnrest.py` to avoid any conflict with this one.  Of course, you could use this one instead!
+
 ## Configuration
 
+If `rest-port` is not specified, the plugin will disable itself.
+
+- --rest-port: Sets the REST server port to listen to (3010 is common)
 - --rest-protocol: Specifies the REST server protocol. Default is HTTPS.
 - --rest-host: Defines the REST server host. Default is 127.0.0.1.
-- --rest-port: Sets the REST server port to listen to. Default is 3010.
 - --rest-certs: Defines the path for HTTPS cert & key. Default path is same as RPC file path to utilize gRPC's client certificate. If it is missing at the configured location, new identity (`client.pem` and `client-key.pem`) will be generated.
 
 ## Plugin

plugins/clnrest/clnrest.py

@@ -110,7 +110,10 @@ def start_server():
 
 @plugin.init()
 def init(options, configuration, plugin):
-    set_config(options)
+    # We require options before we open a port.
+    err = set_config(options)
+    if err:
+        return {'disable': err}
     start_server()
 
 

plugins/clnrest/utilities/rpc_plugin.py

@@ -10,7 +10,7 @@ queue = manager.Queue()
 plugin.add_option(name="rest-certs", default=os.getcwd(), description="Path for certificates (for https)", opt_type="string", deprecated=False)
 plugin.add_option(name="rest-protocol", default="https", description="REST server protocol", opt_type="string", deprecated=False)
 plugin.add_option(name="rest-host", default="127.0.0.1", description="REST server host", opt_type="string", deprecated=False)
-plugin.add_option(name="rest-port", default=3010, description="REST server port to listen", opt_type="int", deprecated=False)
+plugin.add_option(name="rest-port", default=None, description="REST server port to listen", opt_type="int", deprecated=False)
 
 
 @plugin.subscribe("*")

plugins/clnrest/utilities/shared.py

@@ -6,11 +6,14 @@ CERTS_PATH, REST_PROTOCOL, REST_HOST, REST_PORT = "", "", "", ""
 
 
 def set_config(options):
+    if 'rest-port' not in options:
+        return "`rest-port` option is not configured"
     global CERTS_PATH, REST_PROTOCOL, REST_HOST, REST_PORT
     CERTS_PATH = str(options["rest-certs"])
     REST_PROTOCOL = str(options["rest-protocol"])
     REST_HOST = str(options["rest-host"])
     REST_PORT = int(options["rest-port"])
+    return None
 
 
 def call_rpc_method(plugin, rpc_method, payload):