Merge pull request #1779 from guedou/Issue_#1777

Do not crash when tcpdump is not available

Author: guedou

scapy/arch/common.py

@@ -26,9 +26,15 @@
 
 
 def _check_tcpdump():
+    """
+    Return True if the tcpdump command can be started
+    """
     with open(os.devnull, 'wb') as devnull:
-        proc = subprocess.Popen([conf.prog.tcpdump, "--version"],
-                                stdout=devnull, stderr=subprocess.STDOUT)
+        try:
+            proc = subprocess.Popen([conf.prog.tcpdump, "--version"],
+                                    stdout=devnull, stderr=subprocess.STDOUT)
+        except OSError:
+            return False
     return proc.wait() == 0
 
 

test/linux.uts

@@ -344,3 +344,12 @@ if six.PY3:
         l3ps.send(IP(dst="8.8.8.8")/ICMP())
         return True
     assert test_L3PacketSocket_sendto_python3()
+
+= Test _check_tcpdump()
+
+from scapy.arch.common import _check_tcpdump
+
+saved_conf_prog_tcpdump = conf.prog.tcpdump
+conf.prog.tcpdump = "does_not_exist"
+assert _check_tcpdump() == False
+conf.prog.tcpdump = saved_conf_prog_tcpdump