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network_backend: fix crash on lost/refused connection

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getpeername() raised ENOTCONN when a connect failed or the peer
closed the socket, crashing the event loop thread. Identify sockets
via the selector key's data (set at register time) instead, and
catch OSError on recv/send to cleanly close and unregister a dead
socket rather than crashing.

Also fix select(timeout=100) which waited 100 seconds instead of
100ms, causing stop() to hang after a dead socket was unregistered.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
jens
2026-06-12 20:48:17 +02:00
co-authored by Claude Sonnet 4.6
parent e7474efed9
commit 3f6f403b7b
1 changed files with 20 additions and 26 deletions
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backend/network_backend.py
+20 -26
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@@ -20,7 +20,7 @@ class NetworkBackend(ABackend):
sock = self.find_by_name(xcvr.name) sock = self.find_by_name(xcvr.name)
sock['queue'].put(data) sock['queue'].put(data)
if sock is not None: if sock is not None:
self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, None) self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, sock)
def start(self): def start(self):
self.thread.start() self.thread.start()
@@ -42,12 +42,6 @@ class NetworkBackend(ABackend):
if not found: if not found:
raise Exception(f"No socket found for \"{xcvr.name}\"") raise Exception(f"No socket found for \"{xcvr.name}\"")
def find_by_addr(self, addr):
for sock in self.sock_list:
if sock['addr'] == addr:
return sock
return None
def find_by_name(self, name: str): def find_by_name(self, name: str):
for sock in self.sock_list: for sock in self.sock_list:
if sock['name'] == name: if sock['name'] == name:
@@ -66,35 +60,35 @@ class NetworkBackend(ABackend):
events = selectors.EVENT_READ events = selectors.EVENT_READ
for sock in self.sock_list: for sock in self.sock_list:
print(f"Starting connection {sock['name']} to {sock['addr']}") print(f"Starting connection {sock['name']} to {sock['addr']}")
self.sel.register(sock['sock'], events, data=None) self.sel.register(sock['sock'], events, data=sock)
sock['sock'].connect_ex(sock['addr']) sock['sock'].connect_ex(sock['addr'])
def disconnect(self): def disconnect(self):
for sock in self.sock_list: for sock in self.sock_list:
sock['sock'].close() sock['sock'].close()
def on_send(self, name: str, data: bytes):
sock = self.find_by_name(name)
if sock is not None:
self.sel.modify(sock['sock'], selectors.EVENT_READ + selectors.EVENT_WRITE, data)
def event_loop(self): def event_loop(self):
try: try:
while self.loop_enable: while self.loop_enable:
events = self.sel.select(timeout=100) events = self.sel.select(timeout=0.1)
for key, mask in events: for key, mask in events:
descr = self.find_by_addr(key.fileobj.getpeername()) sock = key.data
name = descr['name'] try:
sock = self.find_by_name(name) if mask & selectors.EVENT_READ:
if mask & selectors.EVENT_READ: data = key.fileobj.recv(64)
data = key.fileobj.recv(64) if not data:
sock['xcvr'].on_recv(MsgContainer(data, sock['xcvr'])) raise OSError("connection closed by peer")
if mask & selectors.EVENT_WRITE: sock['xcvr'].on_recv(MsgContainer(data, sock['xcvr']))
data = sock['queue'].get() if mask & selectors.EVENT_WRITE:
key.fileobj.send(data) data = sock['queue'].get()
print(f"Send: {sock['name']}: {data}") key.fileobj.send(data)
if sock['queue'].empty(): print(f"Send: {sock['name']}: {data}")
self.sel.modify(sock['sock'], selectors.EVENT_READ, None) if sock['queue'].empty():
self.sel.modify(sock['sock'], selectors.EVENT_READ, sock)
except OSError as exc:
print(f"Connection {sock['name']} to {sock['addr']} lost: {exc}")
self.sel.unregister(key.fileobj)
key.fileobj.close()
except KeyboardInterrupt: except KeyboardInterrupt:
print("Caught keyboard interrupt, exiting") print("Caught keyboard interrupt, exiting")