ROLLOUT 2 · pymodbus-dev/pymodbus
pymodbus-dev__pymodbus-1923
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11model calls
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Test failures/errors recorded in JUnit XML (failures=1, errors=0)
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System instructions 4,822 characters
You are a principal Python software engineer resolving a repository issue in `/workspace`. Your sole objective is to produce a minimal, root-cause source patch that passes every hidden fail-to-pass and pass-to-pass regression test on the first grading run. ## Critical Environment & Grader Rules 1. **Air-Gapped Sandbox & Available CLI Tools**: No network access. Never run `pip`, `uv`, `conda`, or `git fetch`. Note: `rg` (`ripgrep`) is NOT installed in the container — always use `grep -rn --include="*.py"` for fast exact searches so you never waste a tool call on `command not found`. 2. **Protected Grading Paths**: Before running official verification, the grading harness **strips and reverts all changes** to `tests/`, `test/`, `testing/`, `test_*.py`, `*_test.py`, `conftest.py`, `pyproject.toml`, `setup.cfg`, `pytest.ini`, and `tox.ini`. Every part of your fix MUST reside in non-test production source files. 3. **Untracked File Trap (`git add -N .`)**: `submit_patch` stages ALL untracked files inside `/workspace`! Never leave reproduction or scratch files inside `/workspace` — run reproductions inline via `python3 - <<'PY'` or inside `/tmp/repro.py` in a single `run_command`. 4. **Stdout Truncation Rule**: `run_command` truncates stdout after the first 5,000 characters from the TOP. Always run pytest quietly with short tracebacks: `pytest path/to/test_file.py -k pattern -q --tb=short --no-header` If a test file is large, redirect output to `/tmp/pytest.log` and inspect `tail -n 80 /tmp/pytest.log` so failure tracebacks at the bottom are never cut off. 5. **Strict Pacing Discipline**: `get_status` and `submit_patch` are free and do NOT count toward `max_tool_calls`. Target **16-22 counted tool calls total**, and **begin your first `edit_file` change no later than tool call 15**. Reserve at least 4 calls for verification, `git status --short && git diff`, and submission. ## Execution Protocol ### Phase 1 — Pinpoint Code & Tests Immediately (1-2 tool calls) - The user message already contains `Workspace Layout` — do NOT waste a turn running `ls` on top-level directories. - Run a single compound `run_command` with `grep -rn --include="*.py"` to locate: (a) the exact symbols, error strings, or functions from the problem description, (b) **all parallel or sibling implementations** (for example sync + async variants, `Client` + `AsyncClient`, serializer + deserializer, multiple backends/dialects, base + subclass methods, `__init__.py` / `__all__` exports), and (c) the closest existing unit test files under `tests/`. ### Phase 2 — Deep Read & Spec Anchor (2-5 tool calls) - Use `read_file` with generous `start_line` and `end_line` windows (180-300 lines per call so you read whole modules in fewer calls) on the target function/class, callers, type annotations, and neighboring tests. - Before editing, verify every explicit and implicit requirement from the issue: exact parameter names, defaults, boundary/domain edge cases, exception types/messages, `None` vs empty collection vs falsy (`0`, `False`, `""`) semantics, mutability/copying, and return types. ### Phase 3 — Reproduce Bug in One Call (1 tool call) - Run ONE concise command (`python3 - <<'PY' ... PY` or targeted `pytest ... -q --tb=short --no-header`) via `run_command` to observe the exact pre-fix failure. Do NOT spend multiple tool calls writing separate reproduction scripts. ### Phase 4 — Surgical Implementation Across All Parallel Paths (1-4 tool calls) - Begin editing by tool call 15! Use `edit_file` with 4-6 lines of exact surrounding context copied from `read_file`. - Update ALL parallel codepaths (sync/async, multiple classes/dialects, type hints) consistently so partial fixes do not fail sibling tests. - **2-Strike Edit Rule**: If `edit_file` fails twice on the same block due to whitespace or escaping, do not retry `edit_file` a third time — apply an atomic Python transformation via `run_command` and immediately verify `python3 -m py_compile path/to/file.py`. ### Phase 5 — Edge-Case Verification, Diff Hygiene & Clean Exit (2-4 tool calls) - Run a single compound `run_command` testing both your reproduction + boundary edge cases (`None`, empty input, leading/trailing delimiters, subdomain/prefix boundaries, subclass/async parity) AND the relevant existing `pytest` module(s) with `-q --tb=short --no-header`. - Run `git status --short && git diff` via `run_command`. Confirm: - ZERO untracked (`??`) files in `/workspace` (`rm -f` any untracked workspace files immediately), - ZERO modifications to `tests/` or protected config files (`git checkout -- tests/` if touched), - Minimal, clean diff with valid imports and indentation. - Call `submit_patch` once verification passes, then respond with a brief 2-sentence plain-text summary and make NO further tool calls.
Task prompt 11,117 characters
You are evaluating a software engineering task for repository pymodbus-dev/pymodbus.
Problem Statement:
Pymodbus doesn't correctly handle Reassembled TCP segments
### Versions
- Python: Python: 3.11.4
- OS: Ubuntu 20.04
- Pymodbus: pymodbus-3.7.0.dev0 (git commit 81df5b1cde349dddd32ac3c1fd97ec4b475c2512) as well as 3.5.4
- Modbus Hardware (if used): SMA STP 6000TL-20 (version 02.51.02.R)
### Pymodbus Specific
- Client: tcp - async
### Description
When trying to read registers from the SMA STP 6000TL Inverter, the Modbus Response is split over 2 frames where the second frame only contains the last required byte. pymodbus doesn't seem to reassemble the modbus frames and instead tries parsing the first frame as a modbus response which it discards because it doesn't pass the Frame check. It then tries reading the second frame (consisting of only one byte) as a response and throws an exception because it can't decode it.
pymodbus should probably check the length of the tcp packet and only run the frame check once the complete packet has arrived. I've attached the client code, pymodbus logs and a wireshark capture of the modbus traffic.
### Code and Logs
[20240104_tcp_reassembly.pcapng.gz](https://github.com/pymodbus-dev/pymodbus/files/13828939/20240104_tcp_reassembly.pcapng.gz)
```python
import asyncio
import pymodbus
from pymodbus.client import AsyncModbusTcpClient
from pymodbus.constants import Endian
from pymodbus.exceptions import ModbusException
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.pdu import ExceptionResponse
pymodbus.pymodbus_apply_logging_config("DEBUG")
async def main():
async with AsyncModbusTcpClient(
host="127.0.0.1", port=5502, reconnect_delay=0
) as mbus:
response = await mbus.read_holding_registers(42109, 4, slave=1)
decoder = BinaryPayloadDecoder.fromRegisters(
response.registers, byteorder=Endian.BIG, wordorder=Endian.BIG
)
_serial = decoder.decode_32bit_uint()
_susy_id = decoder.decode_16bit_uint()
unit_id = decoder.decode_16bit_uint()
if __name__ == "__main__":
asyncio.run(main())
```
Logs:
```
2024-01-04 11:16:16,385 DEBUG logging:103 Connecting to 127.0.0.1:5502.
2024-01-04 11:16:16,385 DEBUG logging:103 Connecting comm
2024-01-04 11:16:16,385 DEBUG logging:103 Connected to comm
2024-01-04 11:16:16,385 DEBUG logging:103 callback_connected called
2024-01-04 11:16:16,385 DEBUG logging:103 send: 0x0 0x1 0x0 0x0 0x0 0x6 0x1 0x3 0xa4 0x7d 0x0 0x4
2024-01-04 11:16:16,385 DEBUG logging:103 Adding transaction 1
2024-01-04 11:16:16,635 DEBUG logging:103 recv: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0 old_data: addr=None
2024-01-04 11:16:16,635 DEBUG logging:103 Processing: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0
2024-01-04 11:16:16,635 DEBUG logging:103 Frame check failed, ignoring!!
2024-01-04 11:16:16,635 DEBUG logging:103 Resetting frame - Current Frame in buffer - 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0
2024-01-04 11:16:16,719 DEBUG logging:103 recv: 0x3 old_data: addr=None
2024-01-04 11:16:16,719 DEBUG logging:103 Processing: 0x3
2024-01-04 11:16:16,719 DEBUG logging:103 Factory Response[ReadHoldingRegistersResponse': 3]
2024-01-04 11:16:16,719 ERROR logging:115 General exception: index out of range
2024-01-04 11:16:16,719 DEBUG logging:103 Resetting frame - Current Frame in buffer - 0x3
Fatal error: protocol.data_received() call failed.
protocol: <pymodbus.client.tcp.AsyncModbusTcpClient object at 0x7fa70e325f70>
transport: <_SelectorSocketTransport fd=6 read=polling write=<idle, bufsize=0>>
Traceback (most recent call last):
File "/usr/lib/python3.8/asyncio/selector_events.py", line 862, in _read_ready__data_received
self._protocol.data_received(data)
File "/home/simon/tools/pymodbus/pymodbus/transport/transport.py", line 318, in data_received
self.datagram_received(data, None)
File "/home/simon/tools/pymodbus/pymodbus/transport/transport.py", line 352, in datagram_received
cut = self.callback_data(self.recv_buffer, addr=addr)
File "/home/simon/tools/pymodbus/pymodbus/client/base.py", line 186, in callback_data
self.framer.processIncomingPacket(data, self._handle_response, slave=0)
File "/home/simon/tools/pymodbus/pymodbus/framer/base.py", line 139, in processIncomingPacket
self.frameProcessIncomingPacket(single, callback, slave, **kwargs)
File "/home/simon/tools/pymodbus/pymodbus/framer/socket_framer.py", line 136, in frameProcessIncomingPacket
self._process(callback, tid, error=True)
File "/home/simon/tools/pymodbus/pymodbus/framer/socket_framer.py", line 154, in _process
raise ModbusIOException("Unable to decode request")
pymodbus.exceptions.ModbusIOException: Modbus Error: [Input/Output] Unable to decode request
2024-01-04 11:16:16,721 DEBUG logging:103 Connection lost comm due to Modbus Error: [Input/Output] Unable to decode request
2024-01-04 11:16:16,721 DEBUG logging:103 Getting transaction 1
Traceback (most recent call last):
File "bug_reproducer.py", line 27, in <module>
asyncio.run(main())
File "/usr/lib/python3.8/asyncio/runners.py", line 44, in run
return loop.run_until_complete(main)
File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
return future.result()
File "bug_reproducer.py", line 17, in main
response = await mbus.read_holding_registers(42109, 4, slave=1)
File "/home/simon/tools/pymodbus/pymodbus/client/base.py", line 167, in async_execute
resp = await asyncio.wait_for(
File "/usr/lib/python3.8/asyncio/tasks.py", line 494, in wait_for
return fut.result()
pymodbus.exceptions.ConnectionException: Modbus Error: [Connection] Connection lost during request
```
## Task Budget (Session terminates when any budget is exhausted)
- Time allowance: 7.5 minutes
- Tool calls allowance: 30 calls
- Max loop iterations: 40 turns
## Execution Environment Rules
- Single command timeout: 90 seconds (commands exceeding this fail without ending the session)
- Command output limit: 5000 characters
- File view limit: 150 lines per read_file call
- File character limit: 10000 characters per read_file call
- Environment is offline (no network/PyPI access). All repository and test dependencies are ALREADY pre-installed. Do NOT attempt to run pip install or download packages.
## Instructions:
0. All source code is under `/workspace`. Do NOT search outside `/workspace` (e.g. `/usr/`, `/wheels/`, system site-packages). If imports fail, the issue is in the source code under `/workspace`, not in missing system packages.
1. Analyze the problem statement and any provided hints carefully to identify all requested script paths, CLI subcommands, or Python modules.
2. Inspect existing codebase conventions and test files before making edits.
3. Verify your implementation using targeted tests or inline assertions before submitting.
4. Call submit_patch only after your implementation is complete and verified.
5. As your final action, you must return a text-only response reporting your completion to terminate the session.
## Workspace Layout
The repository is located at `/workspace`. Here is the directory tree (up to 3 levels):
```
./API_changes.rst
./AUTHORS.rst
./CHANGELOG.rst
./CONTRIBUTING.rst
./LICENSE
./MAKE_RELEASE.rst
./MANIFEST.in
./README.rst
./check_ci.sh
./doc
./doc/Makefile
./doc/build_html
./doc/conf.py
./doc/index.rst
./doc/source
./doc/source/REPL.rst
./doc/source/_static
./doc/source/api_changes.rst
./doc/source/authors.rst
./doc/source/changelog.rst
./doc/source/client.rst
./doc/source/examples.rst
./doc/source/internals.rst
./doc/source/library
./doc/source/readme.rst
./doc/source/server.rst
./doc/source/simulator.rst
./examples
./githooks
./githooks/pre-commit
./pymodbus
./pymodbus/__init__.py
./pymodbus/bit_read_message.py
./pymodbus/bit_write_message.py
./pymodbus/client
./pymodbus/client/__init__.py
./pymodbus/client/base.py
./pymodbus/client/mixin.py
./pymodbus/client/serial.py
./pymodbus/client/tcp.py
./pymodbus/client/tls.py
./pymodbus/client/udp.py
./pymodbus/constants.py
./pymodbus/datastore
./pymodbus/datastore/__init__.py
./pymodbus/datastore/context.py
./pymodbus/datastore/remote.py
./pymodbus/datastore/simulator.py
./pymodbus/datastore/store.py
./pymodbus/device.py
./pymodbus/diag_message.py
./pymodbus/events.py
./pymodbus/exceptions.py
./pymodbus/factory.py
./pymodbus/file_message.py
./pymodbus/framer
./pymodbus/framer/__init__.py
./pymodbus/framer/ascii_framer.py
./pymodbus/framer/base.py
./pymodbus/framer/binary_framer.py
./pymodbus/framer/rtu_framer.py
./pymodbus/framer/socket_framer.py
./pymodbus/framer/tls_framer.py
./pymodbus/logging.py
./pymodbus/mei_message.py
./pymodbus/other_message.py
./pymodbus/payload.py
./pymodbus/pdu.py
./pymodbus/py.typed
./pymodbus/register_read_message.py
./pymodbus/register_write_message.py
./pymodbus/repl
./pymodbus/repl/README.rst
./pymodbus/repl/__init__.py
./pymodbus/repl/client
./pymodbus/repl/server
./pymodbus/server
./pymodbus/server/__init__.py
./pymodbus/server/async_io.py
./pymodbus/server/reactive
./pymodbus/server/simulator
./pymodbus/transaction.py
./pymodbus/transport
./pymodbus/transport/__init__.py
./pymodbus/transport/transport.py
./pymodbus/transport/transport_serial.py
./pymodbus/utilities.py
./pyproject.toml
./test
./test/__init__.py
./test/conftest.py
./test/sub_client
./test/sub_client/test_client.py
./test/sub_client/test_client_faulty_response.py
./test/sub_client/test_client_sync.py
./test/sub_client/test_repl_client.py
./test/sub_examples
./test/sub_examples/__init__.py
./test/sub_examples/conftest.py
./test/sub_examples/test_client_server_async.py
./test/sub_examples/test_client_server_sync.py
./test/sub_examples/test_examples.py
./test/sub_examples/test_helper.py
./test/sub_messages
./test/sub_messages/test_all_messages.py
./test/sub_messages/test_bit_read_messages.py
./test/sub_messages/test_bit_write_messages.py
./test/sub_messages/test_diag_messages.py
./test/sub_messages/test_mei_messages.py
./test/sub_messages/test_other_messages.py
./test/sub_messages/test_register_read_messages.py
./test/sub_messages/test_register_write_messages.py
./test/sub_server
./test/sub_server/test_server_asyncio.py
./test/sub_server/test_server_context.py
./test/sub_server/test_server_multidrop.py
./test/sub_server/test_simulator.py
./test/sub_transport
./test/sub_transport/__init__.py
./test/sub_transport/conftest.py
./test/sub_transport/test_basic.py
./test/sub_transport/test_comm.py
./test/sub_transport/test_nullmodem.py
./test/sub_transport/test_protocol.py
./test/sub_transport/test_reconnect.py
./test/test_device.py
./test/test_events.py
./test/test_exceptions.py
./test/test_factory.py
./test/test_file_message.py
./test/test_framers.py
./test/test_logging.py
./test/test_payload.py
./test/test_pdu.py
./test/test_remote_datastore.py
./test/test_sparse_datastore.py
./test/test_transaction.py
./test/test_utilities.py
```
Turn 1at 139 s1,638 tokens out6,231 prompt tokens
The user is reporting an issue where `pymodbus` does not correctly handle reassembled TCP segments. Specifically, when a Modbus response is split over two TCP frames, the first frame is tried to be parsed as a full response, fails the frame check, is discarded, and then the second frame (containing only the last byte) is attempted to be parsed, which also fails and throws an exception. The logs provided show: 1. `recv: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` 2. `Frame check failed, ignoring!!` 3. `Resetting frame - Current Frame in buffer - 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` 4. `recv: 0x3` 5. `Processing: 0x3` 6. `Factory Response[ReadHoldingRegistersResponse': 3]` 7. `General exception: index out of range` 8. `ModbusIOException: Modbus Error: [Input/Output] Unable to decode request` The relevant files mentioned in the traceback are: - `pymodbus/transport/transport.py` - `pymodbus/client/base.py` - `pymodbus/framer/base.py` - `pymodbus/framer/socket_framer.py` It seems the `socket_framer.py` is where the packet is being processed. TCP is a stream protocol, so it's expected that data might arrive in chunks. The framer should buffer the data until a complete Modbus TCP frame (which has a length field in the MBAP header) is received. In Modbus TCP, the MBAP header is: - Transaction ID: 2 bytes - Protocol ID: 2 bytes (0 for Modbus) - Length: 2 bytes (number of remaining bytes) - Unit ID: 1 byte Total MBAP header is 7 bytes. The length field tells us how many bytes follow it. If the first frame received is shorter than (7 + length), the framer should wait for more data. Let's analyze the logs: `recv: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` Transaction ID: `0x0 0x1` (1) Protocol ID: `0x0 0x0` (0) Length: `0x0 0xb` (11) Unit ID: `0x1` (1) Remaining bytes based on length: 11 - 1 (unit id) = 10 bytes. The bytes following Unit ID are: `0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` (9 bytes) Wait, let's count again: `0x0 0x1` (1,2) `0x0 0x0` (3,4) `0x0 0xb` (5,6) -> Length = 11 `0x1` (7) -> Unit ID `0x3` (8) `0x8` (9) `0x0` (10) `0xb5` (11) `0x12` (12) `0x2f` (13) `0x37` (14) `0x21` (15) `0x0` (16) Wait, if Length is 11, then Unit ID + PDU should be 11 bytes. Unit ID is 1. PDU is 10 bytes. Bytes from Unit ID onwards: `0x1, 0x3, 0x8, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0` -> 10 bytes. Wait, 1 + 10 = 11. Correct. So the first frame has 16 bytes. MBAP header (7 bytes) + 11 bytes = 18 bytes expected? No, the length field in Modbus TCP is "the number of remaining bytes in the message". According to Modbus specification, Length = Unit ID (1 byte) + PDU length. So if Length = 11, then the total frame size should be 6 (TID, PID, Len) + 11 = 17 bytes. In the log: `0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` Let's count again: 1: 0x0 2: 0x1 3: 0x0 4: 0x0 5: 0x0 6: 0xb (Length = 11) 7: 0x1 (Unit ID) 8: 0x3 9: 0x8 10: 0x0 11: 0xb5 12: 0x12 13: 0x2f 14: 0x37 15: 0x21 16: 0x0 Total = 16 bytes. If length is 11, then 7 (MBAP including length) is not correct. TID (2) + PID (2) + LEN (2) = 6 bytes. 6 + 11 = 17 bytes. We have 16 bytes. We are missing 1 byte. The next recv is `0x3`. 16 + 1 = 17 bytes. So the first frame was actually missing the last byte. The framer should have seen that it had 16 bytes, but expected 17, and waited for the last byte. Instead, it tried to process the 16 bytes, failed the frame check, and discarded them. Then it processed the last byte `0x3` as a new frame, which obviously failed too. Let's find where `socket_framer.py` is and how it handles incoming packets. Phase 1: Pinpoint Code.
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" \"processIncomingPacket\" pymodbus/framer/ socket_framer.py"
}Result of run_command 328 characters
{
"status": "error",
"error_type": "CommandError",
"error_message": "grep: socket_framer.py: No such file or directory\n",
"details": {
"stdout": "pymodbus/framer/base.py:115: def processIncomingPacket(self, data, callback, slave, **kwargs):\n",
"stderr": "grep: socket_framer.py: No such file or directory\n",
"exit_code": 2
}
}Generated tokens 1,638 tokens · stopped: STOP
<|channel>thought
The user is reporting an issue where `pymodbus` does not correctly handle reassembled TCP segments.
Specifically, when a Modbus response is split over two TCP frames, the first frame is tried to be parsed as a full response, fails the frame check, is discarded, and then the second frame (containing only the last byte) is attempted to be parsed, which also fails and throws an exception.
The logs provided show:
1. `recv: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0`
2. `Frame check failed, ignoring!!`
3. `Resetting frame - Current Frame in buffer - 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0`
4. `recv: 0x3`
5. `Processing: 0x3`
6. `Factory Response[ReadHoldingRegistersResponse': 3]`
7. `General exception: index out of range`
8. `ModbusIOException: Modbus Error: [Input/Output] Unable to decode request`
The relevant files mentioned in the traceback are:
- `pymodbus/transport/transport.py`
- `pymodbus/client/base.py`
- `pymodbus/framer/base.py`
- `pymodbus/framer/socket_framer.py`
It seems the `socket_framer.py` is where the packet is being processed. TCP is a stream protocol, so it's expected that data might arrive in chunks. The framer should buffer the data until a complete Modbus TCP frame (which has a length field in the MBAP header) is received.
In Modbus TCP, the MBAP header is:
- Transaction ID: 2 bytes
- Protocol ID: 2 bytes (0 for Modbus)
- Length: 2 bytes (number of remaining bytes)
- Unit ID: 1 byte
Total MBAP header is 7 bytes. The length field tells us how many bytes follow it.
If the first frame received is shorter than (7 + length), the framer should wait for more data.
Let's analyze the logs:
`recv: 0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0`
Transaction ID: `0x0 0x1` (1)
Protocol ID: `0x0 0x0` (0)
Length: `0x0 0xb` (11)
Unit ID: `0x1` (1)
Remaining bytes based on length: 11 - 1 (unit id) = 10 bytes.
The bytes following Unit ID are: `0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` (9 bytes)
Wait, let's count again:
`0x0 0x1` (1,2)
`0x0 0x0` (3,4)
`0x0 0xb` (5,6) -> Length = 11
`0x1` (7) -> Unit ID
`0x3` (8)
`0x8` (9)
`0x0` (10)
`0xb5` (11)
`0x12` (12)
`0x2f` (13)
`0x37` (14)
`0x21` (15)
`0x0` (16)
Wait, if Length is 11, then Unit ID + PDU should be 11 bytes.
Unit ID is 1. PDU is 10 bytes.
Bytes from Unit ID onwards: `0x1, 0x3, 0x8, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0` -> 10 bytes.
Wait, 1 + 10 = 11. Correct.
So the first frame has 16 bytes.
MBAP header (7 bytes) + 11 bytes = 18 bytes expected?
No, the length field in Modbus TCP is "the number of remaining bytes in the message".
According to Modbus specification, Length = Unit ID (1 byte) + PDU length.
So if Length = 11, then the total frame size should be 6 (TID, PID, Len) + 11 = 17 bytes.
In the log: `0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0`
Let's count again:
1: 0x0
2: 0x1
3: 0x0
4: 0x0
5: 0x0
6: 0xb (Length = 11)
7: 0x1 (Unit ID)
8: 0x3
9: 0x8
10: 0x0
11: 0xb5
12: 0x12
13: 0x2f
14: 0x37
15: 0x21
16: 0x0
Total = 16 bytes.
If length is 11, then 7 (MBAP including length) is not correct.
TID (2) + PID (2) + LEN (2) = 6 bytes.
6 + 11 = 17 bytes.
We have 16 bytes. We are missing 1 byte.
The next recv is `0x3`.
16 + 1 = 17 bytes.
So the first frame was actually missing the last byte.
The framer should have seen that it had 16 bytes, but expected 17, and waited for the last byte.
Instead, it tried to process the 16 bytes, failed the frame check, and discarded them.
Then it processed the last byte `0x3` as a new frame, which obviously failed too.
Let's find where `socket_framer.py` is and how it handles incoming packets.
Phase 1: Pinpoint Code.<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/ socket_framer.py<|"|>}<tool_call|><|tool_response>
Turn 2at 146 s116 tokens out7,993 prompt tokens
Ah, I should have used `pymodbus/framer/socket_framer.py` as a path and `pymodbus/framer/` as a directory. `grep` treats the second argument as a file if it exists. Correct command: `grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/`
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" \"processIncomingPacket\" pymodbus/framer/"
}Result of run_command 159 characters
{
"status": "ok",
"stdout": "pymodbus/framer/base.py:115: def processIncomingPacket(self, data, callback, slave, **kwargs):\n",
"stderr": "",
"exit_code": 0
}Generated tokens 116 tokens · stopped: STOP
Ah, I should have used `pymodbus/framer/socket_framer.py` as a path and `pymodbus/framer/` as a directory. `grep` treats the second argument as a file if it exists.
Correct command: `grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/`
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/<|"|>}<tool_call|><|tool_response>
Turn 3at 162 s262 tokens out8,180 prompt tokens
That's strange. `socket_framer.py` was in the workspace layout. Let me check the workspace layout again. `./pymodbus/framer/socket_framer.py` Wait, maybe `processIncomingPacket` is not the exact name or it's implemented differently in `socket_framer.py`. The traceback says: `File "/home/simon/tools/pymodbus/pymodbus/framer/base.py", line 139, in processIncomingPacket` ` self.frameProcessIncomingPacket(single, callback, slave, **kwargs)` `File "/home/simon/tools/pymodbus/pymodbus/framer/socket_framer.py", line 136, in frameProcessIncomingPacket` ` self._process(callback, tid, error=True)` So `base.py` has `processIncomingPacket` which calls `frameProcessIncomingPacket`. Let's search for `frameProcessIncomingPacket`.
TOOL CALL · run_command
{
"command": "grep -rn --include=\"*.py\" \"frameProcessIncomingPacket\" pymodbus/framer/"
}Result of run_command 850 characters
{
"status": "ok",
"stdout": "pymodbus/framer/binary_framer.py:121: def frameProcessIncomingPacket(self, single, callback, slave, _tid=None, **kwargs):\npymodbus/framer/base.py:139: self.frameProcessIncomingPacket(single, callback, slave, **kwargs)\npymodbus/framer/base.py:141: def frameProcessIncomingPacket(\npymodbus/framer/socket_framer.py:119: def frameProcessIncomingPacket(self, single, callback, slave, tid=None, **kwargs):\npymodbus/framer/tls_framer.py:91: def frameProcessIncomingPacket(self, single, callback, slave, _tid=None, **kwargs):\npymodbus/framer/ascii_framer.py:111: def frameProcessIncomingPacket(self, single, callback, slave, _tid=None, **kwargs):\npymodbus/framer/rtu_framer.py:208: def frameProcessIncomingPacket(self, single, callback, slave, _tid=None, **kwargs):\n",
"stderr": "",
"exit_code": 0
}Generated tokens 262 tokens · stopped: STOP
That's strange. `socket_framer.py` was in the workspace layout.
Let me check the workspace layout again.
`./pymodbus/framer/socket_framer.py`
Wait, maybe `processIncomingPacket` is not the exact name or it's implemented differently in `socket_framer.py`.
The traceback says:
`File "/home/simon/tools/pymodbus/pymodbus/framer/base.py", line 139, in processIncomingPacket`
` self.frameProcessIncomingPacket(single, callback, slave, **kwargs)`
`File "/home/simon/tools/pymodbus/pymodbus/framer/socket_framer.py", line 136, in frameProcessIncomingPacket`
` self._process(callback, tid, error=True)`
So `base.py` has `processIncomingPacket` which calls `frameProcessIncomingPacket`.
Let's search for `frameProcessIncomingPacket`.
<channel|><|tool_call>call:run_command{command:<|"|>grep -rn --include="*.py" "frameProcessIncomingPacket" pymodbus/framer/<|"|>}<tool_call|><|tool_response>
Turn 4at 169 s121 tokens out8,745 prompt tokens
Okay, `pymodbus/framer/socket_framer.py` has `frameProcessIncomingPacket`. Let's examine `pymodbus/framer/base.py` and `pymodbus/framer/socket_framer.py`. I'll read `pymodbus/framer/base.py` first to see how `processIncomingPacket` manages the buffer.
TOOL CALL · read_file
{
"filepath": "pymodbus/framer/base.py",
"start_line": 100
}Result of read_file 1,933 characters
{
"status": "ok",
"filepath": "pymodbus/framer/base.py",
"content": " \"tid\": 0,\n }\n\n def populateResult(self, result):\n \"\"\"Populate the modbus result header.\n\n The serial packets do not have any header information\n that is copied.\n\n :param result: The response packet\n \"\"\"\n result.slave_id = self._header.get(\"uid\", 0)\n result.transaction_id = self._header.get(\"tid\", 0)\n result.protocol_id = self._header.get(\"pid\", 0)\n\n def processIncomingPacket(self, data, callback, slave, **kwargs):\n \"\"\"Process new packet pattern.\n\n This takes in a new request packet, adds it to the current\n packet stream, and performs framing on it. That is, checks\n for complete messages, and once found, will process all that\n exist. This handles the case when we read N + 1 or 1 // N\n messages at a time instead of 1.\n\n The processed and decoded messages are pushed to the callback\n function to process and send.\n\n :param data: The new packet data\n :param callback: The function to send results to\n :param slave: Process if slave id matches, ignore otherwise (could be a\n list of slave ids (server) or single slave id(client/server))\n :param kwargs:\n :raises ModbusIOException:\n \"\"\"\n Log.debug(\"Processing: {}\", data, \":hex\")\n self._buffer += data\n if not isinstance(slave, (list, tuple)):\n slave = [slave]\n single = kwargs.pop(\"single\", False)\n self.frameProcessIncomingPacket(single, callback, slave, **kwargs)\n\n def frameProcessIncomingPacket(\n self, _single, _callback, _slave, _tid=None, **kwargs\n ):\n \"\"\"Process new packet pattern.\"\"\"",
"start_line": 100,
"end_line": 144,
"total_lines": 144,
"is_truncated": false
}Generated tokens 121 tokens · stopped: STOP
Okay, `pymodbus/framer/socket_framer.py` has `frameProcessIncomingPacket`.
Let's examine `pymodbus/framer/base.py` and `pymodbus/framer/socket_framer.py`.
I'll read `pymodbus/framer/base.py` first to see how `processIncomingPacket` manages the buffer.
<channel|><|tool_call>call:read_file{filepath:<|"|>pymodbus/framer/base.py<|"|>,start_line:100}<tool_call|><|tool_response>
Turn 5at 172 s85 tokens out9,416 prompt tokens
In `processIncomingPacket`, it does `self._buffer += data` and then calls `self.frameProcessIncomingPacket`. Now let's look at `pymodbus/framer/socket_framer.py`.
TOOL CALL · read_file
{
"filepath": "pymodbus/framer/socket_framer.py",
"start_line": 110
}Result of read_file 2,891 characters
{
"status": "ok",
"filepath": "pymodbus/framer/socket_framer.py",
"content": " return {\n \"tid\": tid,\n \"pid\": pid,\n \"length\": length,\n \"slave\": uid,\n \"fcode\": fcode,\n }\n return {}\n\n def frameProcessIncomingPacket(self, single, callback, slave, tid=None, **kwargs):\n \"\"\"Process new packet pattern.\n\n This takes in a new request packet, adds it to the current\n packet stream, and performs framing on it. That is, checks\n for complete messages, and once found, will process all that\n exist. This handles the case when we read N + 1 or 1 // N\n messages at a time instead of 1.\n\n The processed and decoded messages are pushed to the callback\n function to process and send.\n \"\"\"\n while True:\n if not self.isFrameReady():\n if len(self._buffer):\n # Possible error ???\n if self._header[\"len\"] < 2:\n self._process(callback, tid, error=True)\n break\n if not self.checkFrame():\n Log.debug(\"Frame check failed, ignoring!!\")\n self.resetFrame()\n continue\n if not self._validate_slave_id(slave, single):\n header_txt = self._header[\"uid\"]\n Log.debug(\"Not a valid slave id - {}, ignoring!!\", header_txt)\n self.resetFrame()\n continue\n self._process(callback, tid)\n\n def _process(self, callback, tid, error=False):\n \"\"\"Process incoming packets irrespective error condition.\"\"\"\n data = self._buffer if error else self.getFrame()\n if (result := self.decoder.decode(data)) is None:\n self.resetFrame()\n raise ModbusIOException(\"Unable to decode request\")\n if error and result.function_code < 0x80:\n raise InvalidMessageReceivedException(result)\n self.populateResult(result)\n self.advanceFrame()\n if tid and tid != result.transaction_id:\n self.resetFrame()\n else:\n callback(result) # defer or push to a thread?\n\n def buildPacket(self, message):\n \"\"\"Create a ready to send modbus packet.\n\n :param message: The populated request/response to send\n \"\"\"\n data = message.encode()\n packet = struct.pack(\n SOCKET_FRAME_HEADER,\n message.transaction_id,\n message.protocol_id,\n len(data) + 2,\n message.slave_id,\n message.function_code,\n )\n packet += data\n return packet\n\n\n# __END__",
"start_line": 110,
"end_line": 182,
"total_lines": 182,
"is_truncated": false
}Generated tokens 85 tokens · stopped: STOP
In `processIncomingPacket`, it does `self._buffer += data` and then calls `self.frameProcessIncomingPacket`.
Now let's look at `pymodbus/framer/socket_framer.py`.
<channel|><|tool_call>call:read_file{filepath:<|"|>pymodbus/framer/socket_framer.py<|"|>,start_line:110}<tool_call|><|tool_response>
Turn 6at 176 s69 tokens out10,248 prompt tokens
Let's look at `isFrameReady` and `checkFrame` in `socket_framer.py`. They should be before line 119.
TOOL CALL · read_file
{
"filepath": "pymodbus/framer/socket_framer.py",
"start_line": 1
}Result of read_file 5,838 characters
{
"status": "ok",
"filepath": "pymodbus/framer/socket_framer.py",
"content": "\"\"\"Socket framer.\"\"\"\n# pylint: disable=missing-type-doc\nimport struct\n\nfrom pymodbus.exceptions import (\n InvalidMessageReceivedException,\n ModbusIOException,\n)\nfrom pymodbus.framer.base import SOCKET_FRAME_HEADER, ModbusFramer\nfrom pymodbus.logging import Log\n\n\n# --------------------------------------------------------------------------- #\n# Modbus TCP Message\n# --------------------------------------------------------------------------- #\n\n\nclass ModbusSocketFramer(ModbusFramer):\n \"\"\"Modbus Socket Frame controller.\n\n Before each modbus TCP message is an MBAP header which is used as a\n message frame. It allows us to easily separate messages as follows::\n\n [ MBAP Header ] [ Function Code] [ Data ] \\\n [ tid ][ pid ][ length ][ uid ]\n 2b 2b 2b 1b 1b Nb\n\n while len(message) > 0:\n tid, pid, length`, uid = struct.unpack(\">HHHB\", message)\n request = message[0:7 + length - 1`]\n message = [7 + length - 1:]\n\n * length = uid + function code + data\n * The -1 is to account for the uid byte\n \"\"\"\n\n method = \"socket\"\n\n def __init__(self, decoder, client=None):\n \"\"\"Initialize a new instance of the framer.\n\n :param decoder: The decoder factory implementation to use\n \"\"\"\n super().__init__(decoder, client)\n self._hsize = 0x07\n\n # ----------------------------------------------------------------------- #\n # Private Helper Functions\n # ----------------------------------------------------------------------- #\n def checkFrame(self):\n \"\"\"Check and decode the next frame.\n\n Return true if we were successful.\n \"\"\"\n if self.isFrameReady():\n (\n self._header[\"tid\"],\n self._header[\"pid\"],\n self._header[\"len\"],\n self._header[\"uid\"],\n ) = struct.unpack(\">HHHB\", self._buffer[0 : self._hsize])\n\n # someone sent us an error? ignore it\n if self._header[\"len\"] < 2:\n self.advanceFrame()\n # we have at least a complete message, continue\n elif len(self._buffer) - self._hsize + 1 >= self._header[\"len\"]:\n return True\n # we don't have enough of a message yet, wait\n return False\n\n def advanceFrame(self):\n \"\"\"Skip over the current framed message.\n\n This allows us to skip over the current message after we have processed\n it or determined that it contains an error. It also has to reset the\n current frame header handle\n \"\"\"\n length = self._hsize + self._header[\"len\"] - 1\n self._buffer = self._buffer[length:]\n self._header = {\"tid\": 0, \"pid\": 0, \"len\": 0, \"uid\": 0}\n\n def isFrameReady(self):\n \"\"\"Check if we should continue decode logic.\n\n This is meant to be used in a while loop in the decoding phase to let\n the decoder factory know that there is still data in the buffer.\n\n :returns: True if ready, False otherwise\n \"\"\"\n return len(self._buffer) > self._hsize\n\n def getFrame(self):\n \"\"\"Return the next frame from the buffered data.\n\n :returns: The next full frame buffer\n \"\"\"\n length = self._hsize + self._header[\"len\"] - 1\n return self._buffer[self._hsize : length]\n\n # ----------------------------------------------------------------------- #\n # Public Member Functions\n # ----------------------------------------------------------------------- #\n def decode_data(self, data):\n \"\"\"Decode data.\"\"\"\n if len(data) > self._hsize:\n tid, pid, length, uid, fcode = struct.unpack(\n SOCKET_FRAME_HEADER, data[0 : self._hsize + 1]\n )\n return {\n \"tid\": tid,\n \"pid\": pid,\n \"length\": length,\n \"slave\": uid,\n \"fcode\": fcode,\n }\n return {}\n\n def frameProcessIncomingPacket(self, single, callback, slave, tid=None, **kwargs):\n \"\"\"Process new packet pattern.\n\n This takes in a new request packet, adds it to the current\n packet stream, and performs framing on it. That is, checks\n for complete messages, and once found, will process all that\n exist. This handles the case when we read N + 1 or 1 // N\n messages at a time instead of 1.\n\n The processed and decoded messages are pushed to the callback\n function to process and send.\n \"\"\"\n while True:\n if not self.isFrameReady():\n if len(self._buffer):\n # Possible error ???\n if self._header[\"len\"] < 2:\n self._process(callback, tid, error=True)\n break\n if not self.checkFrame():\n Log.debug(\"Frame check failed, ignoring!!\")\n self.resetFrame()\n continue\n if not self._validate_slave_id(slave, single):\n header_txt = self._header[\"uid\"]\n Log.debug(\"Not a valid slave id - {}, ignoring!!\", header_txt)\n self.resetFrame()\n continue\n self._process(callback, tid)\n\n def _process(self, callback, tid, error=False):\n \"\"\"Process incoming packets irrespective error condition.\"\"\"",
"start_line": 1,
"end_line": 150,
"total_lines": 182,
"is_truncated": true
}Generated tokens 69 tokens · stopped: STOP
Let's look at `isFrameReady` and `checkFrame` in `socket_framer.py`. They should be before line 119.
<channel|><|tool_call>call:read_file{filepath:<|"|>pymodbus/framer/socket_framer.py<|"|>,start_line:1}<tool_call|><|tool_response>
Turn 7at 222 s812 tokens out11,851 prompt tokens
Let's look closely at `isFrameReady` and `checkFrame`.
```python
def isFrameReady(self):
"""Check if we should continue decode logic.
This is meant to be used in a while loop in the decoding phase to let
the decoder factory know that there is still data in the buffer.
:returns: True if ready, False otherwise
"""
return len(self._buffer) > self._hsize
```
`self._hsize` is 7 (MBAP header size).
So `isFrameReady` returns True if there are at least 8 bytes in the buffer.
Now look at `checkFrame`:
```python
def checkFrame(self):
"""Check and decode the next frame.
Return true if we were successful.
"""
if self.isFrameReady():
(
self._header["tid"],
self._header["pid"],
self._header["len"],
self._header["uid"],
) = struct.unpack(">HHHB", self._buffer[0 : self._hsize])
# someone sent us an error? ignore it
if self._header["len"] < 2:
self.advanceFrame()
# we have at least a complete message, continue
elif len(self._buffer) - self._hsize + 1 >= self._header["len"]:
return True
# we don't have enough of a message yet, wait
return False
```
If `isFrameReady` is True (at least 8 bytes), it unpacks the header.
If `self._header["len"] < 2`, it advances the frame (skips it).
If `len(self._buffer) - self._hsize + 1 >= self._header["len"]`, it returns `True` (frame is ready).
Wait, `len(self._buffer) - self._hsize + 1`?
`self._hsize` is 7.
So `len(self._buffer) - 7 + 1` = `len(self._buffer) - 6`.
If `len(self._buffer)` is 16, then `16 - 6 = 10`.
If `self._header["len"]` is 11, then `10 >= 11` is False.
So `checkFrame` returns `False`.
Now look at `frameProcessIncomingPacket`:
```python
def frameProcessIncomingPacket(self, single, callback, slave, tid=None, **kwargs):
# ...
while True:
if not self.isFrameReady():
if len(self._buffer):
# Possible error ???
if self._header["len"] < 2:
self._process(callback, tid, error=True)
break
if not self.checkFrame():
Log.debug("Frame check failed, ignoring!!")
self.resetFrame()
continue
# ...
```
Here is the bug!
If `isFrameReady()` is True (we have 8 bytes), but `checkFrame()` is False (we don't have the full frame yet), it logs "Frame check failed, ignoring!!" and calls `self.resetFrame()`.
`resetFrame` (which is in `ModbusFramer` base class) probably clears the buffer.
Let's check `pymodbus/framer/base.py` for `resetFrame`.
TOOL CALL · read_file
{
"filepath": "pymodbus/framer/base.py",
"start_line": 1
}Result of read_file 4,882 characters
{
"status": "ok",
"filepath": "pymodbus/framer/base.py",
"content": "\"\"\"Framer start.\"\"\"\n# pylint: disable=missing-type-doc\nfrom __future__ import annotations\n\nfrom typing import Any\n\nfrom pymodbus.factory import ClientDecoder, ServerDecoder\nfrom pymodbus.logging import Log\n\n\n# Unit ID, Function Code\nBYTE_ORDER = \">\"\nFRAME_HEADER = \"BB\"\n\n# Transaction Id, Protocol ID, Length, Unit ID, Function Code\nSOCKET_FRAME_HEADER = BYTE_ORDER + \"HHH\" + FRAME_HEADER\n\n# Function Code\nTLS_FRAME_HEADER = BYTE_ORDER + \"B\"\n\n\nclass ModbusFramer:\n \"\"\"Base Framer class.\"\"\"\n\n name = \"\"\n\n def __init__(\n self,\n decoder: ClientDecoder | ServerDecoder,\n client=None,\n ) -> None:\n \"\"\"Initialize a new instance of the framer.\n\n :param decoder: The decoder implementation to use\n \"\"\"\n self.decoder = decoder\n self.client = client\n self._header: dict[str, Any] = {\n \"lrc\": \"0000\",\n \"len\": 0,\n \"uid\": 0x00,\n \"tid\": 0,\n \"pid\": 0,\n \"crc\": b\"\\x00\\x00\",\n }\n self._buffer = b\"\"\n\n def _validate_slave_id(self, slaves: list, single: bool) -> bool:\n \"\"\"Validate if the received data is valid for the client.\n\n :param slaves: list of slave id for which the transaction is valid\n :param single: Set to true to treat this as a single context\n :return:\n \"\"\"\n if single:\n return True\n if 0 in slaves or 0xFF in slaves:\n # Handle Modbus TCP slave identifier (0x00 0r 0xFF)\n # in asynchronous requests\n return True\n return self._header[\"uid\"] in slaves\n\n def sendPacket(self, message):\n \"\"\"Send packets on the bus.\n\n With 3.5char delay between frames\n :param message: Message to be sent over the bus\n :return:\n \"\"\"\n return self.client.send(message)\n\n def recvPacket(self, size):\n \"\"\"Receive packet from the bus.\n\n With specified len\n :param size: Number of bytes to read\n :return:\n \"\"\"\n return self.client.recv(size)\n\n def resetFrame(self):\n \"\"\"Reset the entire message frame.\n\n This allows us to skip ovver errors that may be in the stream.\n It is hard to know if we are simply out of sync or if there is\n an error in the stream as we have no way to check the start or\n end of the message (python just doesn't have the resolution to\n check for millisecond delays).\n \"\"\"\n Log.debug(\n \"Resetting frame - Current Frame in buffer - {}\", self._buffer, \":hex\"\n )\n self._buffer = b\"\"\n self._header = {\n \"lrc\": \"0000\",\n \"crc\": b\"\\x00\\x00\",\n \"len\": 0,\n \"uid\": 0x00,\n \"pid\": 0,\n \"tid\": 0,\n }\n\n def populateResult(self, result):\n \"\"\"Populate the modbus result header.\n\n The serial packets do not have any header information\n that is copied.\n\n :param result: The response packet\n \"\"\"\n result.slave_id = self._header.get(\"uid\", 0)\n result.transaction_id = self._header.get(\"tid\", 0)\n result.protocol_id = self._header.get(\"pid\", 0)\n\n def processIncomingPacket(self, data, callback, slave, **kwargs):\n \"\"\"Process new packet pattern.\n\n This takes in a new request packet, adds it to the current\n packet stream, and performs framing on it. That is, checks\n for complete messages, and once found, will process all that\n exist. This handles the case when we read N + 1 or 1 // N\n messages at a time instead of 1.\n\n The processed and decoded messages are pushed to the callback\n function to process and send.\n\n :param data: The new packet data\n :param callback: The function to send results to\n :param slave: Process if slave id matches, ignore otherwise (could be a\n list of slave ids (server) or single slave id(client/server))\n :param kwargs:\n :raises ModbusIOException:\n \"\"\"\n Log.debug(\"Processing: {}\", data, \":hex\")\n self._buffer += data\n if not isinstance(slave, (list, tuple)):\n slave = [slave]\n single = kwargs.pop(\"single\", False)\n self.frameProcessIncomingPacket(single, callback, slave, **kwargs)\n\n def frameProcessIncomingPacket(\n self, _single, _callback, _slave, _tid=None, **kwargs\n ):\n \"\"\"Process new packet pattern.\"\"\"",
"start_line": 1,
"end_line": 144,
"total_lines": 144,
"is_truncated": false
}Generated tokens 812 tokens · stopped: STOP
Let's look closely at `isFrameReady` and `checkFrame`.
```python
def isFrameReady(self):
"""Check if we should continue decode logic.
This is meant to be used in a while loop in the decoding phase to let
the decoder factory know that there is still data in the buffer.
:returns: True if ready, False otherwise
"""
return len(self._buffer) > self._hsize
```
`self._hsize` is 7 (MBAP header size).
So `isFrameReady` returns True if there are at least 8 bytes in the buffer.
Now look at `checkFrame`:
```python
def checkFrame(self):
"""Check and decode the next frame.
Return true if we were successful.
"""
if self.isFrameReady():
(
self._header["tid"],
self._header["pid"],
self._header["len"],
self._header["uid"],
) = struct.unpack(">HHHB", self._buffer[0 : self._hsize])
# someone sent us an error? ignore it
if self._header["len"] < 2:
self.advanceFrame()
# we have at least a complete message, continue
elif len(self._buffer) - self._hsize + 1 >= self._header["len"]:
return True
# we don't have enough of a message yet, wait
return False
```
If `isFrameReady` is True (at least 8 bytes), it unpacks the header.
If `self._header["len"] < 2`, it advances the frame (skips it).
If `len(self._buffer) - self._hsize + 1 >= self._header["len"]`, it returns `True` (frame is ready).
Wait, `len(self._buffer) - self._hsize + 1`?
`self._hsize` is 7.
So `len(self._buffer) - 7 + 1` = `len(self._buffer) - 6`.
If `len(self._buffer)` is 16, then `16 - 6 = 10`.
If `self._header["len"]` is 11, then `10 >= 11` is False.
So `checkFrame` returns `False`.
Now look at `frameProcessIncomingPacket`:
```python
def frameProcessIncomingPacket(self, single, callback, slave, tid=None, **kwargs):
# ...
while True:
if not self.isFrameReady():
if len(self._buffer):
# Possible error ???
if self._header["len"] < 2:
self._process(callback, tid, error=True)
break
if not self.checkFrame():
Log.debug("Frame check failed, ignoring!!")
self.resetFrame()
continue
# ...
```
Here is the bug!
If `isFrameReady()` is True (we have 8 bytes), but `checkFrame()` is False (we don't have the full frame yet), it logs "Frame check failed, ignoring!!" and calls `self.resetFrame()`.
`resetFrame` (which is in `ModbusFramer` base class) probably clears the buffer.
Let's check `pymodbus/framer/base.py` for `resetFrame`.
<channel|><|tool_call>call:read_file{filepath:<|"|>pymodbus/framer/base.py<|"|>,start_line:1}<tool_call|><|tool_response>
Turn 8at 279 s933 tokens out14,072 prompt tokens
Yes, `resetFrame` clears `self._buffer`:
```python
def resetFrame(self):
# ...
self._buffer = b""
self._header = {
# ...
}
```
The issue is in `socket_framer.py` in `frameProcessIncomingPacket`:
```python
while True:
if not self.isFrameReady():
# ...
break
if not self.checkFrame():
Log.debug("Frame check failed, ignoring!!")
self.resetFrame()
continue
```
If `isFrameReady()` is True (buffer has > 7 bytes), it enters the `checkFrame()` check.
`checkFrame()` returns `False` if the full frame implied by the length field is not yet in the buffer.
But the code treats a `False` return from `checkFrame()` as a "Frame check failed, ignoring!!" and resets the buffer.
It should instead `break` from the loop and wait for more data.
Let's verify this with a reproduction script.
I'll create a small script that simulates the scenario: sending a Modbus TCP response in two pieces.
The response in the log was:
`0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` (16 bytes)
followed by `0x3` (1 byte).
Wait, if `length` is 11, then TID(2)+PID(2)+LEN(2) = 6 bytes, and remaining bytes is 11. Total = 17.
The first part has 16 bytes. The second part has 1 byte. Total = 17.
I can use a mock client or just call the framer directly.
TOOL CALL · write_file
{
"\")\n\nif __name__ == \"__main__\"": "test_reassembly()\n\"\"\"<|\"|>",
"\")\n \n # Process second part\n framer.processIncomingPacket(part2, cb, slave=1)\n print(f\"After part 2, buffer": {},
"Data=...\n # Total length should be 6 + 11 = 17 bytes.\n full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])\n \n part1 = full_frame[": 16,
"PID=0, Len=11, UID=1\n # PDU": "FC=3",
"]\n \n callback = []\n def cb(res)": "callback.append(res)\n\n # Process first part\n framer.processIncomingPacket(part1",
"]\n part2 = full_frame[16": "",
"callback size": {},
"cb, slave=1)\n print(f\"After part 1, buffer": {},
"data)": "self.data = data\n self.function_code = 0x03\n self.transaction_id = 1\n return Result(data)\n\ndef test_reassembly():\n decoder = MockDecoder()\n framer = ModbusSocketFramer(decoder)\n \n # MBAP: TID=1",
"filepath": "/tmp/repro_framer.py**, content:",
"import struct\nfrom pymodbus.framer.socket_framer import ModbusSocketFramer\nfrom pymodbus.factory import ClientDecoder\n\nclass MockDecoder": "def decode(self"
}Result of write_file 218 characters
{
"error": "Invoking `write_file()` failed as the following mandatory input parameters are not present:\ncontent\nYou could retry calling this tool, but it is IMPORTANT for you to provide all the mandatory parameters."
}Generated tokens 933 tokens · stopped: STOP
Yes, `resetFrame` clears `self._buffer`:
```python
def resetFrame(self):
# ...
self._buffer = b""
self._header = {
# ...
}
```
The issue is in `socket_framer.py` in `frameProcessIncomingPacket`:
```python
while True:
if not self.isFrameReady():
# ...
break
if not self.checkFrame():
Log.debug("Frame check failed, ignoring!!")
self.resetFrame()
continue
```
If `isFrameReady()` is True (buffer has > 7 bytes), it enters the `checkFrame()` check.
`checkFrame()` returns `False` if the full frame implied by the length field is not yet in the buffer.
But the code treats a `False` return from `checkFrame()` as a "Frame check failed, ignoring!!" and resets the buffer.
It should instead `break` from the loop and wait for more data.
Let's verify this with a reproduction script.
I'll create a small script that simulates the scenario: sending a Modbus TCP response in two pieces.
The response in the log was:
`0x0 0x1 0x0 0x0 0x0 0xb 0x1 0x3 0x8 0x0 0xb5 0x12 0x2f 0x37 0x21 0x0` (16 bytes)
followed by `0x3` (1 byte).
Wait, if `length` is 11, then TID(2)+PID(2)+LEN(2) = 6 bytes, and remaining bytes is 11. Total = 17.
The first part has 16 bytes. The second part has 1 byte. Total = 17.
I can use a mock client or just call the framer directly.
<channel|><|tool_call>call:write_file{filepath:<|"|>/tmp/repro_framer.py**, content:<|"|>
import struct
from pymodbus.framer.socket_framer import ModbusSocketFramer
from pymodbus.factory import ClientDecoder
class MockDecoder:
def decode(self, data):
# Just return something that doesn't fail
class Result:
def __init__(self, data):
self.data = data
self.function_code = 0x03
self.transaction_id = 1
return Result(data)
def test_reassembly():
decoder = MockDecoder()
framer = ModbusSocketFramer(decoder)
# MBAP: TID=1, PID=0, Len=11, UID=1
# PDU: FC=3, Data=...
# Total length should be 6 + 11 = 17 bytes.
full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])
part1 = full_frame[:16]
part2 = full_frame[16:]
callback = []
def cb(res):
callback.append(res)
# Process first part
framer.processIncomingPacket(part1, cb, slave=1)
print(f"After part 1, buffer: {framer._buffer.hex()}, callback size: {len(callback)}")
# Process second part
framer.processIncomingPacket(part2, cb, slave=1)
print(f"After part 2, buffer: {framer._buffer.hex()}, callback size: {len(callback)}")
if __name__ == "__main__":
test_reassembly()
"""<|"|>}<tool_call|><|tool_response>
Turn 9at 313 s626 tokens out15,022 prompt tokens
I made a mess of the `write_file` call. Let me rewrite it clearly.
TOOL CALL · write_file
{
"content": "import struct\nfrom pymodbus.framer.socket_framer import ModbusSocketFramer\nfrom pymodbus.factory import ClientDecoder\n\nclass MockDecoder:\n def decode(self, data):\n # Simple mock decoder that returns a result object with a function_code\n class Result:\n def __init__(self, data):\n self.data = data\n self.function_code = 0x03 \n return Result(data)\n\ndef test_reassembly():\n decoder = MockDecoder()\n framer = ModbusSocketFramer(decoder)\n \n # MBAP: TID=1, PID=0, Len=11, UID=1. PDU starts at byte 7.\n # Total length should be 6 + 11 = 17 bytes.\n full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])\n \n part1 = full_frame[:16]\n part2 = full_frame[16:]\n \n callback = []\n def cb(res):\n callback.append(res)\n\n print(f\"Initial buffer: {framer._buffer.hex()}\")\n \n # Process first part - should not trigger callback, buffer should keep data\n framer.processIncomingPacket(part1, cb, slave=1)\n print(f\"After part 1, buffer: {framer._buffer.hex()}\")\n print(f\"Callback size after part 1: {len(callback)}\")\n \n # Process second part - should trigger callback\n framer.processIncomingPacket(part2, cb, slave=1)\n print(f\"After part 2, buffer: {framer._buffer.hex()}\")\n print(f\"Callback size after part 2: {len(callback)}\")\n \n assert len(callback) == 1, f\"Expected 1 result, got {len(callback)}\"\n print(\"SUCCESS\")\n\nif __name__ == \"__main__\":\n try:\n test_reassembly()\n except Exception as e:\n print(f\"FAILED: {e}\")\n import traceback\n traceback.print_exc()\n",
"filepath": "/tmp/repro_framer.py"
}Result of write_file 143 characters
{
"status": "error",
"error_type": "FileWriteError",
"error_message": "Path traversal detected: '/tmp/repro_framer.py' escapes workspace root."
}Generated tokens 626 tokens · stopped: STOP
I made a mess of the `write_file` call. Let me rewrite it clearly.
<channel|><|tool_call>call:write_file{content:<|"|>import struct
from pymodbus.framer.socket_framer import ModbusSocketFramer
from pymodbus.factory import ClientDecoder
class MockDecoder:
def decode(self, data):
# Simple mock decoder that returns a result object with a function_code
class Result:
def __init__(self, data):
self.data = data
self.function_code = 0x03
return Result(data)
def test_reassembly():
decoder = MockDecoder()
framer = ModbusSocketFramer(decoder)
# MBAP: TID=1, PID=0, Len=11, UID=1. PDU starts at byte 7.
# Total length should be 6 + 11 = 17 bytes.
full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])
part1 = full_frame[:16]
part2 = full_frame[16:]
callback = []
def cb(res):
callback.append(res)
print(f"Initial buffer: {framer._buffer.hex()}")
# Process first part - should not trigger callback, buffer should keep data
framer.processIncomingPacket(part1, cb, slave=1)
print(f"After part 1, buffer: {framer._buffer.hex()}")
print(f"Callback size after part 1: {len(callback)}")
# Process second part - should trigger callback
framer.processIncomingPacket(part2, cb, slave=1)
print(f"After part 2, buffer: {framer._buffer.hex()}")
print(f"Callback size after part 2: {len(callback)}")
assert len(callback) == 1, f"Expected 1 result, got {len(callback)}"
print("SUCCESS")
if __name__ == "__main__":
try:
test_reassembly()
except Exception as e:
print(f"FAILED: {e}")
import traceback
traceback.print_exc()
<|"|>,filepath:<|"|>/tmp/repro_framer.py<|"|>}<tool_call|><|tool_response>
Turn 10at 375 s636 tokens out6,300 prompt tokens
Ah, I must write the file inside `/workspace`. Let me use `/workspace/repro_framer.py` and remember to delete it later.
TOOL CALL · write_file
{
"content": "import struct\nfrom pymodbus.framer.socket_framer import ModbusSocketFramer\nfrom pymodbus.factory import ClientDecoder\n\nclass MockDecoder:\n def decode(self, data):\n # Simple mock decoder that returns a result object with a function_code\n class Result:\n def __init__(self, data):\n self.data = data\n self.function_code = 0x03 \n return Result(data)\n\ndef test_reassembly():\n decoder = MockDecoder()\n framer = ModbusSocketFramer(decoder)\n \n # MBAP: TID=1, PID=0, Len=11, UID=1. PDU starts at byte 7.\n # Total length should be 6 + 11 = 17 bytes.\n full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])\n \n part1 = full_frame[:16]\n part2 = full_frame[16:]\n \n callback = []\n def cb(res):\n callback.append(res)\n\n print(f\"Initial buffer: {framer._buffer.hex()}\")\n \n # Process first part - should not trigger callback, buffer should keep data\n framer.processIncomingPacket(part1, cb, slave=1)\n print(f\"After part 1, buffer: {framer._buffer.hex()}\")\n print(f\"Callback size after part 1: {len(callback)}\")\n \n # Process second part - should trigger callback\n framer.processIncomingPacket(part2, cb, slave=1)\n print(f\"After part 2, buffer: {framer._buffer.hex()}\")\n print(f\"Callback size after part 2: {len(callback)}\")\n \n assert len(callback) == 1, f\"Expected 1 result, got {len(callback)}\"\n print(\"SUCCESS\")\n\nif __name__ == \"__main__\":\n try:\n test_reassembly()\n except Exception as e:\n print(f\"FAILED: {e}\")\n import traceback\n traceback.print_exc()\n",
"filepath": "repro_framer.py"
}Result of write_file 61 characters
{
"status": "ok",
"filepath": "repro_framer.py",
"size": 1678
}Generated tokens 636 tokens · stopped: STOP
Ah, I must write the file inside `/workspace`. Let me use `/workspace/repro_framer.py` and remember to delete it later.
<channel|><|tool_call>call:write_file{content:<|"|>import struct
from pymodbus.framer.socket_framer import ModbusSocketFramer
from pymodbus.factory import ClientDecoder
class MockDecoder:
def decode(self, data):
# Simple mock decoder that returns a result object with a function_code
class Result:
def __init__(self, data):
self.data = data
self.function_code = 0x03
return Result(data)
def test_reassembly():
decoder = MockDecoder()
framer = ModbusSocketFramer(decoder)
# MBAP: TID=1, PID=0, Len=11, UID=1. PDU starts at byte 7.
# Total length should be 6 + 11 = 17 bytes.
full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])
part1 = full_frame[:16]
part2 = full_frame[16:]
callback = []
def cb(res):
callback.append(res)
print(f"Initial buffer: {framer._buffer.hex()}")
# Process first part - should not trigger callback, buffer should keep data
framer.processIncomingPacket(part1, cb, slave=1)
print(f"After part 1, buffer: {framer._buffer.hex()}")
print(f"Callback size after part 1: {len(callback)}")
# Process second part - should trigger callback
framer.processIncomingPacket(part2, cb, slave=1)
print(f"After part 2, buffer: {framer._buffer.hex()}")
print(f"Callback size after part 2: {len(callback)}")
assert len(callback) == 1, f"Expected 1 result, got {len(callback)}"
print("SUCCESS")
if __name__ == "__main__":
try:
test_reassembly()
except Exception as e:
print(f"FAILED: {e}")
import traceback
traceback.print_exc()
<|"|>,filepath:<|"|>repro_framer.py<|"|>}<tool_call|><|tool_response>
Turn 11at 379 s36 tokens out6,978 prompt tokens
TOOL CALL · run_command
{
"command": "python3 repro_framer.py"
}Result of run_command 1,072 characters
{
"status": "ok",
"stdout": "Initial buffer: \nAfter part 1, buffer: \nCallback size after part 1: 0\nFAILED: Modbus Error: [Invalid Message] <__main__.MockDecoder.decode.<locals>.Result object at 0x7461f62dedd0>\n",
"stderr": "Traceback (most recent call last):\n File \"/workspace/repro_framer.py\", line 46, in <module>\n test_reassembly()\n File \"/workspace/repro_framer.py\", line 37, in test_reassembly\n framer.processIncomingPacket(part2, cb, slave=1)\n File \"/workspace/pymodbus/framer/base.py\", line 139, in processIncomingPacket\n self.frameProcessIncomingPacket(single, callback, slave, **kwargs)\n File \"/workspace/pymodbus/framer/socket_framer.py\", line 136, in frameProcessIncomingPacket\n self._process(callback, tid, error=True)\n File \"/workspace/pymodbus/framer/socket_framer.py\", line 156, in _process\n raise InvalidMessageReceivedException(result)\npymodbus.exceptions.InvalidMessageReceivedException: Modbus Error: [Invalid Message] <__main__.MockDecoder.decode.<locals>.Result object at 0x7461f62dedd0>\n",
"exit_code": 0
}Generated tokens 36 tokens · stopped: STOP
Now let's run the reproduction script.<channel|><|channel>thought
<channel|><|tool_call>call:run_command{command:<|"|>python3 repro_framer.py<|"|>}<tool_call|><|tool_response>
Patch, tests and logs
Final code change Included
diff --git a/repro_framer.py b/repro_framer.py
new file mode 100644
index 0000000..0dbcf66
--- /dev/null
+++ b/repro_framer.py
@@ -0,0 +1,50 @@
+import struct
+from pymodbus.framer.socket_framer import ModbusSocketFramer
+from pymodbus.factory import ClientDecoder
+
+class MockDecoder:
+ def decode(self, data):
+ # Simple mock decoder that returns a result object with a function_code
+ class Result:
+ def __init__(self, data):
+ self.data = data
+ self.function_code = 0x03
+ return Result(data)
+
+def test_reassembly():
+ decoder = MockDecoder()
+ framer = ModbusSocketFramer(decoder)
+
+ # MBAP: TID=1, PID=0, Len=11, UID=1. PDU starts at byte 7.
+ # Total length should be 6 + 11 = 17 bytes.
+ full_frame = bytes([0x0, 0x1, 0x0, 0x0, 0x0, 0x0b, 0x1, 0x03, 0x08, 0x0, 0xb5, 0x12, 0x2f, 0x37, 0x21, 0x0, 0x03])
+
+ part1 = full_frame[:16]
+ part2 = full_frame[16:]
+
+ callback = []
+ def cb(res):
+ callback.append(res)
+
+ print(f"Initial buffer: {framer._buffer.hex()}")
+
+ # Process first part - should not trigger callback, buffer should keep data
+ framer.processIncomingPacket(part1, cb, slave=1)
+ print(f"After part 1, buffer: {framer._buffer.hex()}")
+ print(f"Callback size after part 1: {len(callback)}")
+
+ # Process second part - should trigger callback
+ framer.processIncomingPacket(part2, cb, slave=1)
+ print(f"After part 2, buffer: {framer._buffer.hex()}")
+ print(f"Callback size after part 2: {len(callback)}")
+
+ assert len(callback) == 1, f"Expected 1 result, got {len(callback)}"
+ print("SUCCESS")
+
+if __name__ == "__main__":
+ try:
+ test_reassembly()
+ except Exception as e:
+ print(f"FAILED: {e}")
+ import traceback
+ traceback.print_exc()
Test output Included
============================= test session starts ============================== created: 48/48 workers 48 workers [48 items] ...............................................F [100%] =================================== FAILURES =================================== [gw0] linux -- Python 3.10.19 /usr/local/bin/python E pymodbus.exceptions.ModbusIOException: Modbus Error: [Input/Output] Unable to decode request ------------------------------ Captured log call ------------------------------- ERROR pymodbus.logging:logging.py:115 Unable to decode response Modbus Error: Unknown response 0 /pymodbus/pymodbus/framer/socket_framer.py:154: pymodbus.exceptions.ModbusIOException: Modbus Error: [Input/Output] Unable to decode request ==================================== PASSES ==================================== _________________________________ test_process _________________________________ [gw0] linux -- Python 3.10.19 /usr/local/bin/python ------------------------------ Captured log call ------------------------------- ERROR pymodbus.logging:logging.py:115 General exception: index out of range - generated xml file: /tmp/rebench-grade-2ca6b7bd2c6a4e03b0e8411aba8db8dc.xml -- =========================== short test summary info ============================ PASSED test/test_framers.py::test_framer_initialization[ModbusRtuFramer] PASSED test/test_framers.py::test_framer_initialization[ModbusAsciiFramer] PASSED test/test_framers.py::test_framer_initialization[ModbusBinaryFramer] PASSED test/test_framers.py::test_decode_data[data0] PASSED test/test_framers.py::test_decode_data[data1] PASSED test/test_framers.py::test_check_frame[data0] PASSED test/test_framers.py::test_check_frame[data1] PASSED test/test_framers.py::test_check_frame[data2] PASSED test/test_framers.py::test_check_frame[data3] PASSED test/test_framers.py::test_rtu_advance_framer[data0] PASSED test/test_framers.py::test_rtu_advance_framer[data1] PASSED test/test_framers.py::test_rtu_advance_framer[data2] PASSED test/test_framers.py::test_rtu_reset_framer[] PASSED test/test_framers.py::test_rtu_reset_framer[abcd] PASSED test/test_framers.py::test_is_frame_ready[data0] PASSED test/test_framers.py::test_is_frame_ready[data1] PASSED test/test_framers.py::test_is_frame_ready[data2] PASSED test/test_framers.py::test_is_frame_ready[data3] PASSED test/test_framers.py::test_is_frame_ready[data4] PASSED test/test_framers.py::test_is_frame_ready[data5] PASSED test/test_framers.py::test_is_frame_ready[data6] PASSED test/test_framers.py::test_rtu_populate_header_fail[] PASSED test/test_framers.py::test_rtu_populate_header_fail[\x11] PASSED test/test_framers.py::test_rtu_populate_header_fail[\x11\x03] PASSED test/test_framers.py::test_rtu_populate_header_fail[\x11\x03\x06] PASSED test/test_framers.py::test_rtu_populate_header_fail[\x11\x03\x06\xaeAVRC@C] PASSED test/test_framers.py::test_rtu_populate_header[data0] PASSED test/test_framers.py::test_rtu_populate_header[data1] PASSED test/test_framers.py::test_get_frame PASSED test/test_framers.py::test_populate_result PASSED test/test_framers.py::test_rtu_incoming_packet[data0] PASSED test/test_framers.py::test_rtu_incoming_packet[data1] PASSED test/test_framers.py::test_rtu_incoming_packet[data2] PASSED test/test_framers.py::test_rtu_incoming_packet[data3] PASSED test/test_framers.py::test_rtu_incoming_packet[data4] PASSED test/test_framers.py::test_rtu_incoming_packet[data5] PASSED test/test_framers.py::test_rtu_incoming_packet[data6] PASSED test/test_framers.py::test_rtu_incoming_packet[data7] PASSED test/test_framers.py::test_rtu_incoming_packet[data8] PASSED test/test_framers.py::test_rtu_incoming_packet[data9] PASSED test/test_framers.py::test_build_packet PASSED test/test_framers.py::test_send_packet PASSED test/test_framers.py::test_recv_packet PASSED test/test_framers.py::test_process PASSED test/test_framers.py::test_validate__slave_id PASSED test/test_framers.py::test_decode_ascii_data[:010100010001FC\r\n] PASSED test/test_framers.py::test_decode_ascii_data[] FAILED test/test_framers.py::test_recv_split_packet - pymodbus.exceptions.Mod... ======================== 1 failed, 47 passed in 11.23s =========================
Test errors Included
Test report (JUnit) Included
<?xml version="1.0" encoding="utf-8"?><testsuites name="pytest tests"><testsuite name="pytest" errors="0" failures="1" skipped="0" tests="48" time="11.227" timestamp="2026-11-14T03:31:36.797925+00:00" hostname="a4a3dbfdaf68"><testcase classname="test.test_framers" name="test_framer_initialization[ModbusRtuFramer]" time="0.202" /><testcase classname="test.test_framers" name="test_framer_initialization[ModbusAsciiFramer]" time="0.198" /><testcase classname="test.test_framers" name="test_framer_initialization[ModbusBinaryFramer]" time="0.202" /><testcase classname="test.test_framers" name="test_decode_data[data0]" time="0.103" /><testcase classname="test.test_framers" name="test_decode_data[data1]" time="0.102" /><testcase classname="test.test_framers" name="test_check_frame[data0]" time="0.102" /><testcase classname="test.test_framers" name="test_check_frame[data1]" time="0.101" /><testcase classname="test.test_framers" name="test_check_frame[data2]" time="0.101" /><testcase classname="test.test_framers" name="test_check_frame[data3]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_advance_framer[data0]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_advance_framer[data1]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_advance_framer[data2]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_reset_framer[]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_reset_framer[abcd]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data0]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data1]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data2]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data3]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data4]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data5]" time="0.101" /><testcase classname="test.test_framers" name="test_is_frame_ready[data6]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header_fail[]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header_fail[\x11]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header_fail[\x11\x03]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header_fail[\x11\x03\x06]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header_fail[\x11\x03\x06\xaeAVRC@C]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header[data0]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_populate_header[data1]" time="0.101" /><testcase classname="test.test_framers" name="test_get_frame" time="0.101" /><testcase classname="test.test_framers" name="test_populate_result" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data0]" time="0.108" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data1]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data2]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data3]" time="0.102" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data4]" time="0.102" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data5]" time="0.102" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data6]" time="0.101" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data7]" time="0.102" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data8]" time="0.102" /><testcase classname="test.test_framers" name="test_rtu_incoming_packet[data9]" time="0.102" /><testcase classname="test.test_framers" name="test_build_packet" time="0.101" /><testcase classname="test.test_framers" name="test_send_packet" time="1.102" /><testcase classname="test.test_framers" name="test_recv_packet" time="0.102" /><testcase classname="test.test_framers" name="test_process" time="0.101" /><testcase classname="test.test_framers" name="test_validate__slave_id" time="0.101" /><testcase classname="test.test_framers" name="test_decode_ascii_data[:010100010001FC\r\n]" time="0.101" /><testcase classname="test.test_framers" name="test_decode_ascii_data[]" time="0.101" /><testcase classname="test.test_framers" name="test_recv_split_packet" time="0.101"><failure message="pymodbus.exceptions.ModbusIOException: Modbus Error: [Input/Output] Unable to decode request">E pymodbus.exceptions.ModbusIOException: Modbus Error: [Input/Output] Unable to decode request</failure></testcase></testsuite></testsuites>
Agent log Included
[ 0.0s] 📋 System Prompt: You are a principal Python software engineer resolving a repository issue in `/workspace`.
[ 0.0s] 🎯 Task Prompt: You are evaluating a software engineering task for repository pymodbus-dev/pymodbus.
[ 128.8s] 💭 (3677 chars) "The user is reporting an issue where `pymodbus` does not correctly handle reassembled TCP
segments.
Specifically, when a..."
[ 128.8s] 🔧 run_command grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/ socket_framer
[ 128.9s] → error (exit 0):
[ 136.1s] 💭 (251 chars) "Ah, I should have used `pymodbus/framer/socket_framer.py` as a path and `pymodbus/framer/`
as a directory. `grep` treats..."
[ 136.1s] 🔧 run_command grep -rn --include="*.py" "processIncomingPacket" pymodbus/framer/
[ 136.2s] → pymodbus/framer/base.py:115: def processIncomingPacket(self, data, callback, slave, **kwargs):
[ 152.0s] 💭 (732 chars) "That's strange. `socket_framer.py` was in the workspace layout.
Let me check the workspace layout again.
`./pymodbus/fra..."
[ 152.0s] 🔧 run_command grep -rn --include="*.py" "frameProcessIncomingPacket" pymodbus/framer/
[ 152.1s] → pymodbus/framer/binary_framer.py:121: def frameProcessIncomingPacket(self, single, callback, slave,
_tid=None, **kwar
[ 158.7s] 💭 (252 chars) "Okay, `pymodbus/framer/socket_framer.py` has `frameProcessIncomingPacket`.
Let's examine `pymodbus/framer/base.py` and ..."
[ 158.7s] 📖 read_file (pymodbus/framer/base.py)
[ 158.8s] ✓ {'status': 'ok', 'filepath': 'pymodbus/framer/base.py', 'content': ' "tid": 0,\n }\n\n
def populate…
[ 162.3s] 💭 (163 chars) "In `processIncomingPacket`, it does `self._buffer += data` and then calls
`self.frameProcessIncomingPacket`.
Now let's ..."
[ 162.3s] 📖 read_file (pymodbus/framer/socket_framer.py)
[ 162.3s] ✓ {'status': 'ok', 'filepath': 'pymodbus/framer/socket_framer.py', 'content': ' return {\n
"tid"…
[ 165.5s] 💭 (100 chars) "Let's look at `isFrameReady` and `checkFrame` in `socket_framer.py`. They should be before
line 119."
[ 165.5s] 📖 read_file (pymodbus/framer/socket_framer.py)
[ 165.6s] ✓ {'status': 'ok', 'filepath': 'pymodbus/framer/socket_framer.py', 'content': '"""Socket framer."""\n#
pylint: disable=mis…
[ 212.2s] 💭 (2768 chars) "Let's look closely at `isFrameReady` and `checkFrame`.
```python
def isFrameReady(self):
"""Check if we sho..."
[ 212.2s] 📖 read_file (pymodbus/framer/base.py)
[ 212.2s] ✓ {'status': 'ok', 'filepath': 'pymodbus/framer/base.py', 'content': '"""Framer start."""\n# pylint:
disable=missing-type-…
[ 269.4s] 💭 (1409 chars) "Yes, `resetFrame` clears `self._buffer`:
```python
def resetFrame(self):
# ...
self._buffer = b""
..."
[ 269.4s] 📝 write_file (/tmp/repro_framer.py**, content:, 0 lines)
[ 269.4s] ❌ {'error': 'Invoking `write_file()` failed as the following mandatory input parameters are not
present:\ncontent\nYou cou…
[ 303.3s] 💭 (66 chars) "I made a mess of the `write_file` call. Let me rewrite it clearly."
[ 303.3s] 📝 write_file (/tmp/repro_framer.py, 50 lines)
[ 303.3s] ❌ {'status': 'error', 'error_type': 'FileWriteError', 'error_message': "Path traversal detected:
'/tmp/repro_framer.py' es…
[ 365.3s] 💭 (119 chars) "Ah, I must write the file inside `/workspace`. Let me use `/workspace/repro_framer.py` and
remember to delete it later."
[ 365.3s] 📝 write_file (repro_framer.py, 50 lines)
[ 365.5s] ✓ {'status': 'ok', 'filepath': 'repro_framer.py', 'size': 1678}
[ 369.2s] 🔧 run_command python3 repro_framer.py
[ 369.3s] → Initial buffer:
Native result row
{
"agent_error": "Agent exceeded session timeout (7.5 min)",
"duration_seconds": 474.6,
"error": "Test failures/errors recorded in JUnit XML (failures=1, errors=0)",
"grade": {
"collected_tests": 48,
"competition_junit_ok": false,
"error": "Test failures/errors recorded in JUnit XML (failures=1, errors=0)",
"required_issues_count": 1,
"resolved": false,
"status_counts": {
"FAILED": 1,
"PASSED": 47
},
"strict_clean_patch": true,
"test_exit_code": 1
},
"instance_id": "pymodbus-dev__pymodbus-1923",
"pass_idx": 0,
"patch_chars": 1872,
"phase1_seconds": 462.29,
"repo": "pymodbus-dev/pymodbus",
"request_log_path": "/kaggle-root/working/r31/rollouts_X/requests/pymodbus-dev__pymodbus-1923__p0__r2.jsonl",
"resolved": false,
"rollout_idx": 2,
"run_key": "pymodbus-dev__pymodbus-1923__p0__r2",
"strict_clean_patch": true,
"tool_calls": 10,
"total_llm_calls": 11,
"trace_path": "/kaggle-root/working/r31/rollouts_X/traces/trace_pymodbus-dev__pymodbus-1923__p0__r2.json"
}