PacketField Does not Fuzz #2804

sarcasticmonkeys · 2020-09-08T12:54:14Z

If you call fuzz on a layer that contains a PacketField, that fuzz does not recurse down into a PacketField within the layer

class Foo(Packet):
    name='Foo'
    fields_desc=[
        int64("bar"),
    ]
    def extract_padding(self, s):
        return b'', s
        
class demo(Packet):
    name="demo"
    fields_desc = [ PacketField(name="foo",default=Foo(),cls=Foo)]
instance = demo()
print(fuzz(instance).show())

Results in:

###[ demo ]### 
  \foo       \
   |###[ Foo ]### 
   |  bar       = 0

None

What do people think of modifying

scapy/scapy/packet.py

Line 2252 in 54da22f

elif isinstance(f, MultipleTypeField):

to add

            elif isinstance(f, PacketField):
                if(f.default is not None):
                    fuzz(getattr(q, f.name),_inplace=1)

resulting in

###[ demo ]### 
  \foo       \
   |###[ Foo ]### 
   |  bar       = <RandSLong>

None

To me this makes sense, but I'm obviously very new to this.

gpotter2 · 2020-09-16T15:18:26Z

This sounds pretty reasonable. Feel free to submit a PR.
You can also use the holds_packets field attribute to see if it holds a packet, this is more general than testing for PacketField (but watch out PacketListField).

Thanks for the suggestion

gpotter2 added the enhancement label Sep 16, 2020

gpotter2 added good first issue Hacktoberfest labels Sep 25, 2020

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secdev / scapy

PacketField Does not Fuzz #2804

PacketField Does not Fuzz #2804

sarcasticmonkeys commented Sep 8, 2020

gpotter2 commented Sep 16, 2020

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PacketField Does not Fuzz #2804

PacketField Does not Fuzz #2804

Comments

sarcasticmonkeys commented Sep 8, 2020

gpotter2 commented Sep 16, 2020