verification server changes

* show message on startup
* add help to argparser options
* make hostname optional
* set hostname to addr if not specified
* make sure hostname is not `0.0.0.0`

aputils/__main__.py

@@ -2,6 +2,7 @@
 import aputils
 import argparse
 import json
+import socket
 
 from functools import cached_property, lru_cache
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
@@ -11,6 +12,16 @@ from urllib.error import HTTPError
 from urllib.request import Request, urlopen
 
 
+def get_machine_addr() -> str:
+	with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
+		try:
+			sock.connect(("10.254.254.255", 1))
+			return sock.getsockname()[0]
+
+		except Exception as e:
+			return "127.0.0.1"
+
+
 class ClientError(Exception):
 	...
 
@@ -261,13 +272,26 @@ parser = argparse.ArgumentParser(
 	description = "Starts a server for validating HTTP signatures"
 )
 
-parser.add_argument("hostname")
-parser.add_argument("--addr", "-a", default = "0.0.0.0")
-parser.add_argument("--port", "-p", default = 8080, type = int)
-parser.add_argument("--size-limit", "-s", default = 1024 * 1024, type = int)
-parser.add_argument("--protocol", "-r", default = "https", choices = ["https", "http"])
+parser.add_argument("--hostname", "-n",
+	help = "Domain or address this server will be hosted on (defaults to --addr value)")
+
+parser.add_argument("--addr", "-a", default = "0.0.0.0",
+	help = "IP address to listen on")
+
+parser.add_argument("--port", "-p", default = 8080, type = int,
+	help = "TCP port to listen on")
+
+parser.add_argument("--size-limit", "-s", default = 1024 * 1024, type = int,
+	help = "Max size of incoming or outgoing messages in bytes")
+
+parser.add_argument("--protocol", "-r", default = "http", choices = ["https", "http"],
+	help = "Supported protocol to advertise via the actor at /actor")
 
 args = parser.parse_args()
+
+if args.hostname is None:
+	args.hostname = args.addr if args.addr != "0.0.0.0" else get_machine_addr()
+
 URL = f"{args.protocol}://{args.hostname}"
 keyid = URL + "/actor#main-key"
 
@@ -278,5 +302,11 @@ if not (key := Path("privkey.pem")).exists():
 else:
 	signer = aputils.Signer(key, keyid)
 
+print(f"Starting server on {args.protocol}://{args.hostname} ({args.addr}:{args.port})")
 server = ThreadingHTTPServer((args.addr, args.port), RequestHandler)
-server.serve_forever()
+
+try:
+	server.serve_forever()
+
+except KeyboardInterrupt:
+	pass