fix(engines): require scapy>=2.6.0 in the Scapy and dev extras (#1572)

Pipfile

@@ -14,7 +14,8 @@ tbtrim = "~=0.3.1"
 pypcapkit = {editable = true,path = "."}
 pyshark = "*"
 dpkt = "*"
-scapy = "*"
+# The floor and marker match the Scapy extra in pyproject.toml (#1572).
+scapy = {version = ">=2.6.0",markers = "python_version >= '3.7'"}
 cryptography = "*"
 # NB: ``pypcap`` is deliberately absent. It builds a C extension against
 # libpcap, so listing it here would break ``pipenv install --dev`` -- and even

docs/source/index.rst

@@ -436,9 +436,13 @@ preflight described under `Engine Comparison`_.
 .. note::
 
    Only the four engines above carry extra constraints. :mod:`pcapkit` itself and
-   its ``default``, ``dpkt`` and ``scapy`` engines need nothing further --
-   ``dpkt`` 1.9.8 and ``scapy`` 2.7.0 were both measured reading a capture on
-   Python 3.14.
+   its ``default``, ``dpkt`` and ``scapy`` engines need nothing beyond their
+   ``pip install`` -- ``dpkt`` 1.9.8 and ``scapy`` 2.7.0 were both measured
+   reading a capture on Python 3.14. The ``scapy`` engine needs **scapy 2.6.0 or
+   newer**, which the ``Scapy`` extra requires: 2.5.0 can drop a PCAP-NG
+   interface's timestamp resolution, reading nanoseconds as microseconds
+   (:issue:`1572`). :mod:`pcapkit` does not check the version at run time, so
+   upgrade a scapy installed some other way.
 
 For CLI usage, you will need to install the optional packages:
 

pyproject.toml

@@ -139,7 +139,12 @@ crypto = [ "cryptography>=3.4" ]
 NGAP = [ "pycrate" ]
 # for normal users
 DPKT = [ "dpkt" ]
-Scapy = [ "scapy" ]
+# The floor is measured, #1572: on scapy 2.5.0 a PCAP-NG interface's
+# ``if_tsresol`` is lost after a comment option without a newline, so a
+# nanosecond interface reads as microseconds, and ``packet2dict`` reports DNS
+# records and field order differently. 2.6.0, the next release, fixes all three.
+# It needs Python 3.7, hence the marker, as ``PCAP_CT``'s below.
+Scapy = [ "scapy>=2.6.0; python_version >= '3.7'" ]
 PyShark = [ "pyshark" ]
 # pypcap ships no wheels, so this compiles a C extension against libpcap and
 # needs both its headers and its shared library present; deliberately kept out
@@ -255,7 +260,8 @@ all = [ "emoji", "cryptography>=3.4", "pycrate" ]
 # and it is not a place to add ``pypcap``/``pcap-ct`` just to silence a
 # finding CI has already decided to carry as advisory.
 dev = [
-    "dpkt", "scapy", "pyshark",
+    # scapy: the same floor and marker as the Scapy extra above, #1572
+    "dpkt", "scapy>=2.6.0; python_version >= '3.7'", "pyshark",
     # same marker and reasoning as the PyPCAPFile extra above and the old
     # ``all``: on 3.12+ the package installs cleanly and is then unusable, so
     # the marker keeps the resolver from fetching something that could never

tests/test_tier_guard.py

@@ -1055,6 +1055,20 @@ def test_dev_carries_what_all_used_to_for_the_toolchain(self) -> None:
             with self.subTest(absent=absent):
                 self.assertFalse(_dependency_gates.provided_by(declared['dev'], absent))
 
+    def test_scapy_is_floored_at_the_first_release_main_passes_on(self) -> None:
+        """#1572: ``Scapy`` and ``dev`` both require ``scapy>=2.6.0``.
+
+        On 2.5.0 ``main`` reads a PCAP-NG nanosecond interface as microseconds and
+        ``packet2dict`` reports DNS records and field order differently; 2.6.0, the
+        next release, fixes all three. The marker is ``PCAP_CT``'s courtesy: 2.6.0
+        needs Python 3.7, above this project's ``requires-python`` floor.
+
+        """
+        declared = _dependency_gates.declared_requirements()
+        floor = "scapy>=2.6.0; python_version >= '3.7'"
+        self.assertEqual([requirement.text for requirement in declared['Scapy']], [floor])
+        self.assertIn(floor, [requirement.text for requirement in declared['dev']])
+
     def test_the_core_dependencies_are_read_from_project_not_build_system(self) -> None:
         """``[build-system] requires`` also holds ``setuptools``; this is not it."""
         core = _dependency_gates.declared_requirements()[_dependency_gates.CORE]