Re: [PATCH v6 0/6] flow_parser: add shared parser library

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 27 Jan 2026 22:05:25 +0100
Lukas Sismis <sismis@dyna-nic.com> wrote:

> This series extracts the testpmd flow CLI parser into a reusable library,
> enabling external applications to parse rte_flow rules using testpmd syntax.
> 
> Motivation
> ----------
> External applications like Suricata IDS [1] need to express hardware filtering
> rules in a consistent, human-readable format. Rather than inventing custom
> syntax, reusing testpmd's well-tested flow grammar provides immediate
> compatibility with existing documentation and user knowledge.
> 
> Note: This library provides only one way to create rte_flow structures.
> Applications can also construct rte_flow_attr, rte_flow_item[], and
> rte_flow_action[] directly in C code.
> 
> Design
> ------
> The library (librte_flow_parser) exposes the following APIs:
> - rte_flow_parser_parse_attr_str(): Parse attributes only
> - rte_flow_parser_parse_pattern_str(): Parse patterns only
> - rte_flow_parser_parse_actions_str(): Parse actions only
> 
> Testpmd is updated to use the library, ensuring a single
> maintained parser implementation.
> 
> Testing and Demo
> -------
> - Functional tests in dpdk-test
> - Example application: examples/flow_parsing
> 
> Changes
> -------
> 
> v6:
> - Inconsistent Experimental API Version adjusted
> - Fixes Tag added to MSVC build commit
> - Non-Standard Header Guards updated
> - Implicit Pointer Comparison and Return Type issues addressed in many places
> - commit message in patch 6 updated
> 
> v5:
> - removed/replaced (f)printf code from the library 
> - reverted back to exporting the internal/private API as it is needed by
>   testpmd and cannot be easily split further.
> - adjusted length of certain lines
> - marking port/queue id typedef as experimental
> - updated release rel_notes
> - copyeright adjustments
> 
> 
> v4:
> - ethdev changes in separate commit
> - library's public API only exposes attribute, pattern and action parsing,
>   while the full command parsing is kept internal for testpmd usage only.
> - Addressed Stephen's comments from V3
> - dpdk-test now have tests focused on public and internal library functions
> 
> v3:
> - Add more functional tests
> - More concise MAINTAINERS updates
> - Updated license headers
> - A thing to note: When playing with flow commands, I figured, some may use
>   non-flow commands, such as raw decap/encap, policy meter and others.
>   Flow parser library itself now supports `set` command to set e.g. the decap/
>   encap parameters, as the flow syntax only supports defining the index of the
>   encap/decap configs. The library, however, does not support e.g. `create`
>   command to create policy meters, as that is just an ID and it can be created
>   separately using rte_meter APIs.
> 
> [1] https://github.com/OISF/suricata/pull/13950
> 
> Lukas Sismis (6):
>   cmdline: include stddef.h for MSVC compatibility
>   ethdev: add RSS type helper APIs
>   flow_parser: add shared parser library
>   app/testpmd: use shared flow parser library
>   examples/flow_parsing: add flow parser demo
>   test: add flow parser library functional tests
> 
>  MAINTAINERS                                   |     6 +-
>  app/test-pmd/cmd_flex_item.c                  |    41 +-
>  app/test-pmd/cmdline.c                        |   267 +-
>  app/test-pmd/config.c                         |   112 +-
>  app/test-pmd/flow_parser.c                    |   409 +
>  app/test-pmd/flow_parser_cli.c                |   153 +
>  app/test-pmd/meson.build                      |     5 +-
>  app/test-pmd/testpmd.c                        |     4 +
>  app/test-pmd/testpmd.h                        |   126 +-
>  app/test/meson.build                          |     1 +
>  app/test/test_ethdev_api.c                    |    51 +
>  app/test/test_flow_parser.c                   |   923 ++
>  doc/api/doxy-api-index.md                     |     1 +
>  doc/api/doxy-api.conf.in                      |     1 +
>  doc/guides/prog_guide/flow_parser_lib.rst     |   111 +
>  doc/guides/prog_guide/index.rst               |     1 +
>  doc/guides/rel_notes/release_26_03.rst        |    21 +
>  examples/flow_parsing/main.c                  |   291 +
>  examples/flow_parsing/meson.build             |    11 +
>  examples/meson.build                          |     1 +
>  lib/cmdline/cmdline_parse.h                   |     2 +
>  lib/ethdev/rte_ethdev.c                       |   107 +
>  lib/ethdev/rte_ethdev.h                       |    77 +
>  lib/flow_parser/meson.build                   |     7 +
>  .../flow_parser/rte_flow_parser.c             | 11430 ++++++++--------
>  lib/flow_parser/rte_flow_parser.h             |   124 +
>  lib/flow_parser/rte_flow_parser_private.h     |  1247 ++
>  lib/meson.build                               |     2 +
>  28 files changed, 9698 insertions(+), 5834 deletions(-)
>  create mode 100644 app/test-pmd/flow_parser.c
>  create mode 100644 app/test-pmd/flow_parser_cli.c
>  create mode 100644 app/test/test_flow_parser.c
>  create mode 100644 doc/guides/prog_guide/flow_parser_lib.rst
>  create mode 100644 examples/flow_parsing/main.c
>  create mode 100644 examples/flow_parsing/meson.build
>  create mode 100644 lib/flow_parser/meson.build
>  rename app/test-pmd/cmdline_flow.c => lib/flow_parser/rte_flow_parser.c (55%)
>  create mode 100644 lib/flow_parser/rte_flow_parser.h
>  create mode 100644 lib/flow_parser/rte_flow_parser_private.h
> 


There are only a couple of minor nits left to keep me from putting this in next-net.
There is a check comparing pointer against 0 and the example is using
headers not found on Windows.



### Patch 3/6: flow_parser: add shared parser library

**Error** (must fix):

1. **Incorrect NULL checks in parse helper functions** (lines ~15667 and ~15692):
```c
if (src == NULL || pattern == NULL || pattern_n == 0)  // BUG: should be pattern_n == NULL
```
```c
if (src == NULL || actions == NULL || actions_n == 0)  // BUG: should be actions_n == NULL
```
These check if the *count* is zero rather than if the *pointer* is NULL. This will cause incorrect behavior when passing valid pointers.

**Warning** (should fix):

2. **Thread safety documentation** — The documentation states "The parser is not thread-safe" but the public header doesn't include this warning in the API docstrings. Add `@warning Not thread-safe` to each public function's Doxygen comment.

3. **Missing error return in `rte_flow_parser_init()`** — The function signature shows `int` return but I don't see error handling for double-initialization or invalid state.

---

### Patch 5/6: examples/flow_parsing: add example
**Warning**:
- Uses `<arpa/inet.h>` which is not portable to Windows. Consider using DPDK's byte order macros or conditional compilation.

---


### Required Fix
```c
// In rte_flow_parser_parse_pattern_str():
-   if (src == NULL || pattern == NULL || pattern_n == 0)
+   if (src == NULL || pattern == NULL || pattern_n == NULL)

// In rte_flow_parser_parse_actions_str():  
-   if (src == NULL || actions == NULL || actions_n == 0)
+   if (src == NULL || actions == NULL || actions_n == NULL)
```