From 7d8dca1ffd6e713618999dcee39e729b99e3a967 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=90=D0=BD=D1=82=D0=BE=D0=BD=20=D0=A2=D1=80=D0=BE=D1=88?=
 =?UTF-8?q?=D0=B8=D0=BD?= <i@atroshin.ru>
Date: Sun, 6 Sep 2026 21:09:04 +0300
Subject: [PATCH] Fix GSMTAP capture restart: recreate UDP socket on start
 after stop
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GsmtapListener.stop() closed the UDP socket permanently, but start()
only set _running=True without recreating it. Second capture session
would silently spin on the dead socket (OSError → None → continue).

- Add _closed flag to GsmtapReceiver, set in close()
- Store bind_port in GsmtapListener for socket recreation
- start() recreates GsmtapReceiver only if previous one was closed
- Uses getattr for backward compat with test fakes
---
 simtrace2_pysniff/gsmtap.py         | 2 ++
 simtrace2_pysniff/server/capture.py | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/simtrace2_pysniff/gsmtap.py b/simtrace2_pysniff/gsmtap.py
index 75e5abd..6f9e7a8 100644
--- a/simtrace2_pysniff/gsmtap.py
+++ b/simtrace2_pysniff/gsmtap.py
@@ -79,6 +79,7 @@ class GsmtapReceiver:
         self._sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         self._sock.bind((bind_ip, bind_port))
         self._sock.settimeout(1.0)
+        self._closed = False
 
     def read_packet(self):
         """Block until a GSMTAP-SIM packet arrives.
@@ -109,3 +110,4 @@ class GsmtapReceiver:
 
     def close(self):
         self._sock.close()
+        self._closed = True
diff --git a/simtrace2_pysniff/server/capture.py b/simtrace2_pysniff/server/capture.py
index 0369904..6d0b5ae 100644
--- a/simtrace2_pysniff/server/capture.py
+++ b/simtrace2_pysniff/server/capture.py
@@ -34,11 +34,14 @@ def gsmtap_msg_type(sub_type):
 
 class GsmtapListener:
     def __init__(self, bind_port=4729):
+        self._bind_port = bind_port
         self._receiver = GsmtapReceiver(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._running = True
         self._dropped = 0