Merge pull request #26 from kti/25-Crash-in-iptables-OUTPUT-chain

25 crash in iptables output chain

README.rst

@@ -81,9 +81,8 @@ From source
 
 To install from source::
 
-    wget https://pypi.python.org/packages/94/5b/83d10952c1312fe056f8f2f524a4a59fdc9d56b84a67cae1ed779e2da50b/NetfilterQueue-0.8.tar.gz#md5=8e78db992ad3a73dd86fef05293fff65
-    tar -xvzf NetfilterQueue-0.8.tar.gz
-    cd NetfilterQueue-0.8
+    git clone git@github.com:kti/python-netfilterqueue.git
+    cd python-netfilterqueue
     python setup.py install
 
 If Cython is installed, Distutils will use it to regenerate the .c source from the .pyx. It will then compile the .c into a .so.

examples/print_and_accept.py

@@ -3,6 +3,9 @@ from netfilterqueue import NetfilterQueue
 
 def print_and_accept(pkt):
     print(pkt)
+    hw = pkt.get_hw()
+    if hw:
+        print(":".join("{:02x}".format(ord(c)) for c in hw[0:6]))
     pkt.accept()
 
 nfqueue = NetfilterQueue()

netfilterqueue.pyx

@@ -5,7 +5,7 @@ function.
 Copyright: (c) 2011, Kerkhoff Technologies Inc.
 License: MIT; see LICENSE.txt
 """
-VERSION = (0, 8, 0)
+VERSION = (0, 8, 1)
 
 # Constants for module users
 COPY_NONE = 0
@@ -57,12 +57,10 @@ cdef class Packet:
         self._qh = qh
         self._nfa = nfa
         self._hdr = nfq_get_msg_packet_hdr(nfa)
-        self._hw = nfq_get_packet_hw(nfa)
 
         self.id = ntohl(self._hdr.packet_id)
         self.hw_protocol = ntohs(self._hdr.hw_protocol)
         self.hook = self._hdr.hook
-        self.hw_addr = self._hw.hw_addr
 
         self.payload_len = nfq_get_payload(self._nfa, &self.payload)
         if self.payload_len < 0:
@@ -101,6 +99,11 @@ cdef class Packet:
 
     def get_hw(self):
         """Return the hardware address as Python string."""
+        self._hw = nfq_get_packet_hw(self._nfa)
+        if self._hw == NULL:
+            # nfq_get_packet_hw doesn't work on OUTPUT and PREROUTING chains
+            return None
+        self.hw_addr = self._hw.hw_addr
         cdef object py_string
         if cpython.version.PY_MAJOR_VERSION >= 3:
             py_string = PyBytes_FromStringAndSize(<char*>self.hw_addr, 8)

setup.py

@@ -1,6 +1,6 @@
 from distutils.core import setup, Extension
 
-VERSION = "0.8" # Remember to change README.rst and netfilterqueue.pyx when version changes.
+VERSION = "0.8.1" # Remember to change netfilterqueue.pyx when version changes.
 
 try:
     # Use Cython