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server: keep request/access log out of the pySim output capture

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The HTTP access log (log_message) and the --log-requests REQUEST/RESPONSE
lines wrote to the rebindable sys.stderr, so a concurrent card-free request
(the 2s /api/status poll) dropped its log line into the StringIO a card
command was capturing - corrupting file content read during a snapshot scan
(the access-log line appeared inside the file hex).

- Add _log_stderr(): write the request/access log to fd 2 directly (the same
  bypass the APDU tracer already uses), so it can never enter a capture.
  Route log_message, _log_req and _log_resp through it.
- Add _capture_app_output() context manager and deduplicate the six handlers
  (cardinfo/command/help/read/write/tree) that did the inline
  app.stdout/sys.stderr = out save/restore dance.

Bumps VERSION to 3.40.5 and the SW cache to simple-v491.
This commit is contained in:
catarrh committed 2026-11-08 12:51:13 +03:00
1 parent c4b64788b0
commit 011de4ae82
6 files changed
+172 -70
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CHANGELOG.md
+20
View File
@@ -9,6 +9,26 @@ every change carries a descriptive commit message.
## [Unreleased]
## [3.40.5] — 2026-11-08
### Fixed
- **Server request/access log leaked into captured file content.** The HTTP
access log (`log_message`) and the `--log-requests` `REQUEST`/`RESPONSE`
lines wrote to the rebindable `sys.stderr`, so a concurrent card-free request
(the 2 s `/api/status` poll) dropped its log line into the `StringIO` a
card command was capturing — corrupting file content read during a snapshot
scan (the log line appeared in the snapshot, e.g.
`127.0.0.1 - - […] "GET /api/status HTTP/1.1" 200 -ffff…`). The log now
writes to fd 2 via `_log_stderr`, exactly as the APDU tracer already does.
### Changed
- **Deduplicated the pySim output capture.** The six handlers that captured
pySim command output by rebinding `sys.stdout`/`sys.stderr` to a `StringIO`
now share one `_capture_app_output` context manager (the same save/set/
restore semantics, in one place).
## [3.40.4] — 2026-11-04
### Added
frontend/index.html
+1 -1
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@@ -1990,7 +1990,7 @@
// ===== Version =====
// Single source of truth for the PWA version: shown in the header and used
// by the server version check in pysimConnect().
const SIMPLE_VERSION = '3.40.4';
const SIMPLE_VERSION = '3.40.5';
document.getElementById('app-version').textContent = 'v' + SIMPLE_VERSION;
// ===== view history (the browser Back/Forward buttons) =====
frontend/sw.js
+1 -1
View File
@@ -1,4 +1,4 @@
const CACHE = 'simple-v490';
const CACHE = 'simple-v491';
const URLS = [
'index.html',
'help.html',
pyproject.toml
+1 -1
View File
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
[project]
name = "pysim-simple-server"
version = "3.40.4"
version = "3.40.5"
description = "HTTP REST server wrapping pysim for the SIMple PWA"
license = { text = "GPL-2.0-or-later" }
requires-python = ">=3.9"
pysim_simple_server/server.py
+58 -67
View File
@@ -13,6 +13,7 @@ from urllib.parse import unquote_plus
from datetime import datetime, timedelta
from http.server import BaseHTTPRequestHandler
from io import StringIO
from contextlib import contextmanager
from pySim.transport import ApduTracer, ProactiveHandler
from pySim.cards import UiccCardBase
from pysim_simple_server import httpota
@@ -37,7 +38,7 @@ from osmocom.tlv import BER_TLV_IE
from osmocom.utils import rpad
VERSION = '3.40.4'
VERSION = '3.40.5'
MAX_ENVELOPE_SEGMENTS = 5 # max SMS segments for outgoing C-APDU in ENVELOPE
@@ -267,6 +268,42 @@ def _cmd_exception(output):
return 'command failed'
def _log_stderr(msg):
"""Write a server log line to the real stderr fd, bypassing ``sys.stderr``.
The HTTP handlers temporarily rebind the global ``sys.stderr`` to a
``StringIO`` to capture pySim command output. Concurrent card-free
requests (the 2 s /api/status poll) log via ``log_message`` / ``_log_req``
/ ``_log_resp``; writing to ``sys.stderr`` would drop those lines into the
active capture buffer and corrupt the file content (the snapshot "access
log line in contents" bug). Writing to fd 2 keeps the request log out of
the capture, exactly as the APDU tracer already does below."""
os.write(2, msg.encode())
@contextmanager
def _capture_app_output(app):
"""Temporarily capture the pySim app's output into a ``StringIO``.
cmd2 writes command output to ``app.stdout``; stray writes to the global
``sys.stderr`` (``print(file=sys.stderr)``, ``sys.stderr.write``, logging,
tracebacks) are captured too by rebinding it. Card access is serialized by
``_CARD_LOCK``, so only one capture is active at a time, and the server's
own request/access logging bypasses it via ``_log_stderr``. Yields the
buffer and restores both streams in ``finally``.
"""
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
yield out
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
def _parse_help_text(text):
result = {'usage': '', 'description': '', 'args': []}
lines = text.split('\n')
@@ -9472,13 +9509,13 @@ class PysimHandler(BaseHTTPRequestHandler):
def _log_req(self, body=None):
if self.server.log_requests:
if body is not None:
sys.stderr.write("REQUEST %s %s: %s\n" % (self.command, self.path, json.dumps(body)))
_log_stderr("REQUEST %s %s: %s\n" % (self.command, self.path, json.dumps(body)))
else:
sys.stderr.write("REQUEST %s %s\n" % (self.command, self.path))
_log_stderr("REQUEST %s %s\n" % (self.command, self.path))
def _log_resp(self, data):
if self.server.log_requests:
sys.stderr.write("RESPONSE %s: %s\n" % (self.path, json.dumps(data, ensure_ascii=False)))
_log_stderr("RESPONSE %s: %s\n" % (self.path, json.dumps(data, ensure_ascii=False)))
def do_OPTIONS(self):
self._log_req()
@@ -9777,19 +9814,12 @@ class PysimHandler(BaseHTTPRequestHandler):
self._send_json({'error': _err('app_not_init', lang)}, 503)
self._log_resp({'error': _err('app_not_init', lang)})
return
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
app.onecmd_plus_hooks('cardinfo')
output = _strip_ansi(out.getvalue())
except Exception as e:
output = str(e) + '\n' + traceback.format_exc()
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
with _capture_app_output(app) as out:
try:
app.onecmd_plus_hooks('cardinfo')
output = _strip_ansi(out.getvalue())
except Exception as e:
output = str(e) + '\n' + traceback.format_exc()
resp = {'output': output}
self._send_json(resp)
self._log_resp(resp)
@@ -9931,19 +9961,12 @@ class PysimHandler(BaseHTTPRequestHandler):
# transport so a manual Equip recovers too.
_ensure_transport(self.server)
t0 = time.time()
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
stop = app.onecmd_plus_hooks(cmd)
output = _strip_ansi(out.getvalue())
except Exception as e:
output = str(e) + '\n' + traceback.format_exc()
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
with _capture_app_output(app) as out:
try:
stop = app.onecmd_plus_hooks(cmd)
output = _strip_ansi(out.getvalue())
except Exception as e:
output = str(e) + '\n' + traceback.format_exc()
elapsed = int((time.time() - t0) * 1000)
status = 'OK' if not output or 'not a recognized command' not in output else 'ERROR'
if is_equip:
@@ -10199,17 +10222,9 @@ class PysimHandler(BaseHTTPRequestHandler):
body = self._read_body()
self._log_req(body)
cmd = body.get('cmd', '')
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
with _capture_app_output(app) as out:
app.onecmd_plus_hooks('help ' + cmd)
raw = out.getvalue()
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
clean = _strip_ansi(raw)
parsed = _parse_help_text(clean)
self._send_json(parsed)
@@ -10307,17 +10322,9 @@ class PysimHandler(BaseHTTPRequestHandler):
cmd = 'read_records_decoded' if is_record else 'read_binary_decoded'
else:
cmd = 'read_records' if is_record else 'read_binary'
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
with _capture_app_output(app) as out:
app.onecmd_plus_hooks(cmd)
output = _strip_ansi(out.getvalue())
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
finally:
apdu_times = _end_apdu_time_collection()
exc = _cmd_exception(output)
@@ -10403,17 +10410,9 @@ class PysimHandler(BaseHTTPRequestHandler):
cmd = 'update_record 1 %s' % data
else:
cmd = 'update_binary %s' % data
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
with _capture_app_output(app) as out:
app.onecmd_plus_hooks(cmd)
output = out.getvalue()
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
exc = _cmd_exception(output)
if exc:
resp = {'success': False, 'error': exc}
@@ -10472,17 +10471,9 @@ class PysimHandler(BaseHTTPRequestHandler):
sel = fid if fid else name
_, cleanup = _select_with_parent(lchan, sel, parent_sel, app, parent_path, allow_probe)
cur = lchan.selected_file
out = StringIO()
old_stdout = app.stdout
old_stderr = sys.stderr
app.stdout = out
sys.stderr = out
try:
with _capture_app_output(app) as out:
app.onecmd_plus_hooks('tree')
output = _strip_ansi(out.getvalue())
finally:
app.stdout = old_stdout
sys.stderr = old_stderr
children = _parse_tree_output(output)
# EF.PBR (TS 31.102 4.4.2.1): the phonebook files the DF's PBR
# references are not in pySim's model, so they are appended to
@@ -12178,4 +12169,4 @@ class PysimHandler(BaseHTTPRequestHandler):
self._log_resp({'error': _err('not_found', lang)})
def log_message(self, format, *args):
sys.stderr.write('%s - - [%s] %s\n' % (self.client_address[0], self.log_date_time_string(), format % args))
_log_stderr('%s - - [%s] %s\n' % (self.client_address[0], self.log_date_time_string(), format % args))
tests/test_output_capture.py
+91
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@@ -0,0 +1,91 @@
"""The request/access log must never enter a pySim output capture.
Handlers capture pySim output by temporarily rebinding the global ``sys.stderr``
to a StringIO (``_capture_app_output``). Concurrent card-free requests (the 2 s
/api/status poll) log via ``log_message`` / ``_log_req`` / ``_log_resp``; if
those wrote to ``sys.stderr`` their lines would land in the active capture
buffer and corrupt the file content (the snapshot "access log line in contents"
bug). The log now writes to fd 2 directly, and the capture is a context
manager that restores both streams.
"""
import io
import pathlib
import sys
import types
import unittest
from unittest import mock
from pysim_simple_server import server as srv
from pysim_simple_server.server import PysimHandler, _capture_app_output, _log_stderr
class LogStderrTests(unittest.TestCase):
def test_log_stderr_writes_to_fd2_not_the_rebindable_stream(self):
writes = []
err = io.StringIO()
with mock.patch.object(srv.os, 'write', side_effect=lambda fd, data: writes.append((fd, data))), \
mock.patch('sys.stderr', new=err):
_log_stderr('hello\n')
self.assertEqual(writes, [(2, b'hello\n')])
self.assertEqual(err.getvalue(), '')
def test_log_message_goes_to_fd2(self):
h = object.__new__(PysimHandler)
h.client_address = ('127.0.0.1', 1234)
h.log_date_time_string = lambda: '05/Nov/2026 14:09:10'
writes = []
err = io.StringIO()
with mock.patch.object(srv.os, 'write', side_effect=lambda fd, data: writes.append((fd, data))), \
mock.patch('sys.stderr', new=err):
h.log_message('"%s" %s %s', 'GET /api/status HTTP/1.1', '200', '-')
self.assertEqual(
writes,
[(2, b'127.0.0.1 - - [05/Nov/2026 14:09:10] '
b'"GET /api/status HTTP/1.1" 200 -\n')])
self.assertEqual(err.getvalue(), '',
'the access log must not land in a redirected sys.stderr')
class CaptureOutputTests(unittest.TestCase):
def test_captures_both_streams_and_restores(self):
orig_stdout = io.StringIO()
app = types.SimpleNamespace(stdout=orig_stdout)
real_stderr = sys.stderr
with _capture_app_output(app) as out:
app.stdout.write('AABB\n')
sys.stderr.write('SW: 9000\n')
self.assertIn('AABB\n', out.getvalue())
self.assertIn('SW: 9000\n', out.getvalue())
self.assertIs(app.stdout, orig_stdout)
self.assertIs(sys.stderr, real_stderr)
def test_restores_on_exception(self):
orig_stdout = io.StringIO()
app = types.SimpleNamespace(stdout=orig_stdout)
real_stderr = sys.stderr
with self.assertRaises(RuntimeError):
with _capture_app_output(app) as out:
app.stdout.write('partial\n')
raise RuntimeError('boom')
self.assertIs(app.stdout, orig_stdout)
self.assertIs(sys.stderr, real_stderr)
class SourcePinTests(unittest.TestCase):
def test_log_message_uses_fd2(self):
src = pathlib.Path(srv.__file__).read_text()
seg = src[src.index('def log_message('):]
self.assertIn('_log_stderr(', seg)
self.assertNotIn('sys.stderr.write', seg)
def test_the_handlers_use_the_capture_context_manager(self):
# The six handlers that capture pySim output share one context manager;
# a re-introduced inline ``sys.stderr = out`` block would be a
# thread-safety regression.
src = pathlib.Path(srv.__file__).read_text()
self.assertGreaterEqual(src.count('with _capture_app_output(app) as out:'), 6)
if __name__ == '__main__':
unittest.main()