[PATCH v3 0/7] pcapng: fixes and improvements

[Stephen Hemminger <stephen@networkplumber.org>]

This series addresses several issues in the pcapng library
and improves test coverage.  Several of these patches were
submitted previously in other series but have been more throughly
tested and passed AI review.

Bug Fixes:

Patches 1-3 fix potential issues with string handling in the pcapng
administrative APIs. The pcapng file format uses 16-bit length fields
for option data, but the library did not validate input string
lengths, and used fixed-size stack buffers that could be overrun by
large comments or metadata strings.

    Patch 1 adds length validation against the format's 16-bit limit
    Patch 2 replaces fixed stack buffers with dynamic allocation
    Patch 3 handles the case where comment options
       exceed available mbuf tailroom by chaining an additional mbuf segment

Test Improvements:

Patches 4-6 improve the pcapng unit test coverage:

    Patch 4 exercises the comment option code path with varied test strings
    Patch 5 varies packet sizes to exercise more of the copy logic
    Patch 6 ensures the test runs long enough to verify 32-bit TSC wraparound handling

Performance:

Patch 7 optimizes timestamp conversion by replacing division
operations with shift-multiply arithmetic, following the approach used
by the Linux kernel vDSO. This eliminates expensive divides from the
packet capture hot path.

Stephen Hemminger (7):
  pcapng: add length checks to string arguments
  pcapng: use malloc instead of fixed buffer size
  pcapng: add additional mbuf if space required on copy
  test: add more tests for comments in pcapng
  test: vary size of packets in pcapng test
  test: increase gap in pcapng test
  pcapng: improve performance of timestamping

 app/test/test_pcapng.c  | 134 ++++++++++++++++++++++++++----------
 lib/pcapng/rte_pcapng.c | 147 +++++++++++++++++++++++++++++-----------
 lib/pcapng/rte_pcapng.h |   8 ++-
 3 files changed, 211 insertions(+), 78 deletions(-)

-- 
2.51.0