Tiny Python 3 fixes (#820)

* Python3: fix set_promisc() with Linux

* Fix debug dissector error message

* Make run_scapy3 executable

scapy/arch/linux.py

@@ -163,7 +163,7 @@ def attach_filter(s, bpf_filter, iface):
     s.setsockopt(SOL_SOCKET, SO_ATTACH_FILTER, bpfh)
 
 def set_promisc(s,iff,val=1):
-    mreq = struct.pack("IHH8s", get_if_index(iff), PACKET_MR_PROMISC, 0, "")
+    mreq = struct.pack("IHH8s", get_if_index(iff), PACKET_MR_PROMISC, 0, b"")
     if val:
         cmd = PACKET_ADD_MEMBERSHIP
     else:

scapy/packet.py

@@ -701,7 +701,7 @@ class Packet(six.with_metaclass(Packet_metaclass, BasePacket)):
             except:
                 if conf.debug_dissector:
                     if isinstance(cls,type) and issubclass(cls,Packet):
-                        log_runtime.error("%s dissector failed" % cls.name)
+                        log_runtime.error("%s dissector failed" % cls.__name__)
                     else:
                         log_runtime.error("%s.guess_payload_class() returned [%s]" % (self.__class__.__name__,repr(cls)))
                     if cls is not None: