Add Packet accessors for interface indices

oremanj · oremanj · commit 2d9b171e9ea5 · 2023-03-01T00:42:20.000-07:00
diff --git a/CHANGES.txt b/CHANGES.txt
@@ -1,3 +1,6 @@
+v1.1.0, unreleased
+    Add Packet accessors for {indev, outdev, physindev, physoutdev} interface indices
+
 v1.0.0, 14 Jan 2022
     Propagate exceptions raised by the user's packet callback
     Avoid calls to the packet callback during queue unbinding
diff --git a/README.rst b/README.rst
@@ -217,6 +217,18 @@ Objects of this type are passed to your callback.
     into our queue. Values 0 through 4 correspond to PREROUTING, INPUT,
     FORWARD, OUTPUT, and POSTROUTING respectively.
 
+``Packet.indev``, ``Packet.outdev``, ``Packet.physindev``, ``Packet.physoutdev``
+    The interface indices on which the packet arrived (``indev``) or is slated
+    to depart (``outdev``). These are integers, which can be converted to
+    names like "eth0" by using ``socket.if_indextoname()``. Zero means
+    no interface is applicable, either because the packet was locally generated
+    or locally received, or because the interface information wasn't available
+    when the packet was queued (for example, ``PREROUTING`` rules don't yet
+    know the ``outdev``). If the ``indev`` or ``outdev`` refers to a bridge
+    device, then the corresponding ``physindev`` or ``physoutdev`` will name
+    the bridge member on which the actual traffic occurred; otherwise
+    ``physindev`` and ``physoutdev`` will be zero.
+
 ``Packet.retain()``
     Allocate a copy of the packet payload for use after the callback
     has returned. ``get_payload()`` will raise an exception at that
diff --git a/netfilterqueue/_impl.pxd b/netfilterqueue/_impl.pxd
@@ -153,7 +153,11 @@ cdef extern from "libnetfilter_queue/libnetfilter_queue.h":
     int nfq_get_payload(nfq_data *nfad, unsigned char **data)
     int nfq_get_timestamp(nfq_data *nfad, timeval *tv)
     nfqnl_msg_packet_hw *nfq_get_packet_hw(nfq_data *nfad)
-    int nfq_get_nfmark (nfq_data *nfad)
+    int nfq_get_nfmark(nfq_data *nfad)
+    u_int32_t nfq_get_indev(nfq_data *nfad)
+    u_int32_t nfq_get_outdev(nfq_data *nfad)
+    u_int32_t nfq_get_physindev(nfq_data *nfad)
+    u_int32_t nfq_get_physoutdev(nfq_data *nfad)
     nfnl_handle *nfq_nfnlh(nfq_handle *h)
 
 # Dummy defines from linux/socket.h:
@@ -184,8 +188,7 @@ cdef class NetfilterQueue:
 
 cdef class Packet:
     cdef NetfilterQueue _queue
-    cdef bint _verdict_is_set # True if verdict has been issued,
-        # false otherwise
+    cdef bint _verdict_is_set # True if verdict has been issued, false otherwise
     cdef bint _mark_is_set # True if a mark has been given, false otherwise
     cdef bint _hwaddr_is_set
     cdef bint _timestamp_is_set
@@ -204,13 +207,10 @@ cdef class Packet:
     cdef unsigned char *payload
     cdef timeval timestamp
     cdef u_int8_t hw_addr[8]
-
-    # TODO: implement these
-    #cdef readonly u_int32_t nfmark
-    #cdef readonly u_int32_t indev
-    #cdef readonly u_int32_t physindev
-    #cdef readonly u_int32_t outdev
-    #cdef readonly u_int32_t physoutdev
+    cdef readonly u_int32_t indev
+    cdef readonly u_int32_t physindev
+    cdef readonly u_int32_t outdev
+    cdef readonly u_int32_t physoutdev
 
     cdef set_nfq_data(self, NetfilterQueue queue, nfq_data *nfa)
     cdef drop_refs(self)
diff --git a/netfilterqueue/_impl.pyi b/netfilterqueue/_impl.pyi
@@ -11,6 +11,11 @@ class Packet:
     hw_protocol: int
     id: int
     mark: int
+    # These are ifindexes, pass to socket.if_indextoname() to get names:
+    indev: int
+    outdev: int
+    physindev: int
+    physoutdev: int
     def get_hw(self) -> Optional[bytes]: ...
     def get_payload(self) -> bytes: ...
     def get_payload_len(self) -> int: ...
diff --git a/netfilterqueue/_impl.pyx b/netfilterqueue/_impl.pyx
@@ -99,6 +99,10 @@ cdef class Packet:
 
         nfq_get_timestamp(nfa, &self.timestamp)
         self.mark = nfq_get_nfmark(nfa)
+        self.indev = nfq_get_indev(nfa)
+        self.outdev = nfq_get_outdev(nfa)
+        self.physindev = nfq_get_physindev(nfa)
+        self.physoutdev = nfq_get_physoutdev(nfa)
 
     cdef drop_refs(self):
         """
diff --git a/tests/test_basic.py b/tests/test_basic.py
@@ -119,11 +119,13 @@ def cb(chan, pkt):
     assert t0 < timestamps[0] < t1
 
 
-async def test_hwaddr(harness):
+async def test_hwaddr_and_inoutdev(harness):
     hwaddrs = []
+    inoutdevs = []
 
     def cb(pkt):
         hwaddrs.append((pkt.get_hw(), pkt.hook, pkt.get_payload()[28:]))
+        inoutdevs.append((pkt.indev, pkt.outdev))
         pkt.accept()
 
     queue_num, nfq = harness.bind_queue(cb)
@@ -162,6 +164,15 @@ async def listen_for_packets():
         (None, OUTPUT, b"four"),
     ]
 
+    iface1 = socket.if_nametoindex("veth1")
+    iface2 = socket.if_nametoindex("veth2")
+    assert inoutdevs == [
+        (iface1, iface2),
+        (iface1, iface2),
+        (0, iface2),
+        (0, iface2),
+    ]
+
 
 async def test_errors(harness):
     with pytest.warns(RuntimeWarning, match="rcvbuf limit is") as record:
