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PacketField Does not Fuzz #2804

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sarcasticmonkeys opened this issue Sep 8, 2020 · 4 comments
Open

PacketField Does not Fuzz #2804

sarcasticmonkeys opened this issue Sep 8, 2020 · 4 comments
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enhancement good first issue

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@sarcasticmonkeys
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@sarcasticmonkeys sarcasticmonkeys commented Sep 8, 2020

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
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@gpotter2 gpotter2 commented Sep 16, 2020

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
@badsketch
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@badsketch badsketch commented Oct 4, 2020

I'd like to give this a shot if nobody else has claimed it yet 🙂
@gpotter2
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@gpotter2 gpotter2 commented Oct 4, 2020

@badsketch Sure, have a shot ! Feel free to ask questions If you get stuck somewhere 😄
@badsketch
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@badsketch badsketch commented Oct 26, 2020

Bit off more than I could chew, and don't think I can make a valuable contribution very soon. I'll keep working away on it in my own time, but if anyone else can implement this, please go ahead! Apologies for the late update. 😕
@gpotter2 gpotter2 removed the Hacktoberfest label Nov 2, 2020
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Labels
enhancement good first issue
3 participants
@badsketch @gpotter2 @sarcasticmonkeys
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