GSMTAP: --gsmtap-bind to listen beyond loopback (containers)

A container's 127.0.0.1 is its own loopback, so a GSMTAP feed sent to the
container's bridge address never reached the listener: it was hard-bound to
127.0.0.1.

- `simtrace-analyser-server --gsmtap-bind ADDR` (default 127.0.0.1) is passed
  through GsmtapListener to GsmtapReceiver (whose bind_ip already existed),
  including the receiver re-created by a start() after close.  The startup
  banner prints the effective bind address next to the port.
- READMEs (EN/RU) document the option, naming the container case.
- tests: the listener forwards the address on construction and on start(),
  binds 0.0.0.0, and keeps the loopback default.

Verified end-to-end: with --gsmtap-bind 0.0.0.0 the socket listens on
0.0.0.0:14732 and an ATR + APDU sent to 127.0.0.1:14732 landed in the capture
session (2 messages); without the flag it listens on 127.0.0.1.
557 Python + 80 Node tests.

simtrace_analyser/__main__.py

@@ -1,7 +1,8 @@
 """simtrace-analyser-server — CLI entry point.
 
 Usage:
-    simtrace-analyser-server --capture gsmtap [--gsmtap-port 4729] [--port 8081]
+    simtrace-analyser-server --capture gsmtap [--gsmtap-bind 0.0.0.0]
+        [--gsmtap-port 4729] [--port 8081]
     simtrace-analyser-server --capture direct [--port 8081]
 """
 
@@ -46,6 +47,9 @@ def main():
                    help='Capture mode: gsmtap (listen UDP 4729), direct (SIMtrace2 USB), or disabled (no capture)')
     p.add_argument('--gsmtap-port', type=int, default=4729,
                     help='UDP port for GSMTAP listener (default: 4729)')
+    p.add_argument('--gsmtap-bind', default='127.0.0.1', metavar='ADDR',
+                   help='UDP bind address for the GSMTAP listener '
+                        '(default: 127.0.0.1; use 0.0.0.0 in a container)')
     p.add_argument('--log-interval', type=float, default=60.0,
                     help='Seconds between capture liveness heartbeat logs '
                          '(default: 60.0)')
@@ -61,7 +65,7 @@ def main():
 
     capture = None
     if args.capture == 'gsmtap':
-        backend = GsmtapListener(bind_port=args.gsmtap_port)
+        backend = GsmtapListener(bind_ip=args.gsmtap_bind, bind_port=args.gsmtap_port)
         capture = CaptureManager(backend, db, log_interval=args.log_interval)
     elif args.capture == 'direct':
         backend = DirectSniffer()
@@ -78,6 +82,7 @@ def main():
     print(f'simtrace-analyser-server v{__version__} — http://{args.host}:{args.port}', file=sys.stderr)
     print(f'  capture mode: {args.capture}', file=sys.stderr)
     if args.capture == 'gsmtap':
+        print(f'  GSMTAP bind:  {args.gsmtap_bind}', file=sys.stderr)
         print(f'  GSMTAP port:  {args.gsmtap_port}', file=sys.stderr)
     print(f'  database:     {args.db}', file=sys.stderr)
     print(f'  PWA served at http://{args.host}:{args.port}/', file=sys.stderr)

simtrace_analyser/capture.py

@@ -39,15 +39,17 @@ def gsmtap_msg_type(sub_type):
 
 
 class GsmtapListener:
-    def __init__(self, bind_port=4729):
+    def __init__(self, bind_port=4729, bind_ip='127.0.0.1'):
         self._bind_port = bind_port
-        self._receiver = GsmtapReceiver(bind_port=bind_port)
+        self._bind_ip = bind_ip
+        self._receiver = GsmtapReceiver(bind_ip=bind_ip, bind_port=bind_port)
         self._running = False
         self._dropped = 0
 
     def start(self):
         if getattr(self._receiver, '_closed', False):
-            self._receiver = GsmtapReceiver(bind_port=self._bind_port)
+            self._receiver = GsmtapReceiver(bind_ip=self._bind_ip,
+                                            bind_port=self._bind_port)
         self._running = True
         self._dropped = 0