From 1e59ef63c8d647c1557ffebcdc775ccb5a8b70c0 Mon Sep 17 00:00:00 2001
From: Phil <phil@secdev.org>
Date: Wed, 21 Apr 2010 18:21:44 +0200
Subject: [PATCH] Simplified the build mecanism
Packet.build() is called only on the first layer. It will call
Packet.do_build() which will recurse through all layers. For each layer,
it will call Packet.self_build() which will do the job for each layer.
Packet.do_build() will call Packet.post_build() and transform on them,
and concatenate them. Then Packet.build() will call Packet.build_padding()
and Packet.build_done().
Note that this undetermined case will have a different behavior:
Raw("ABC")/Padding("abc")/Raw("DEF")/Padding("def")
It was "ABCabcDEFdef"
Now it is "ABCDEFabcdef"
---
scapy/asn1packet.py | 2 +-
scapy/packet.py | 56 ++++++++++++++++++++++++++-------------------
test/regression.uts | 2 +-
3 files changed, 35 insertions(+), 25 deletions(-)
diff --git a/scapy/asn1packet.py b/scapy/asn1packet.py
index dc900b0a..e49942ce 100644
--- a/scapy/asn1packet.py
+++ b/scapy/asn1packet.py
@@ -12,7 +12,7 @@ class ASN1_Packet(Packet):
flist = self.ASN1_root.get_fields_list()
self.do_init_fields(flist)
self.fields_desc = flist
- def do_build(self):
+ def self_build(self):
return self.ASN1_root.build(self)
def do_dissect(self, x):
return self.ASN1_root.dissect(self, x)
diff --git a/scapy/packet.py b/scapy/packet.py
index 1f51f318..3410a925 100644
--- a/scapy/packet.py
+++ b/scapy/packet.py
@@ -281,37 +281,44 @@ class Packet(BasePacket):
return True
def __len__(self):
return len(self.__str__())
- def do_build(self):
+ def self_build(self, field_pos_list=None):
p=""
for f in self.fields_desc:
val = self.getfieldval(f.name)
if isinstance(val, RawVal):
- p += str(val)
+ sval = str(val)
+ p += sval
+ if field_pos_list is not None:
+ field_pos_list.append( (f.name, sval.encode("string_escape"), len(p), len(sval) ) )
else:
p = f.addfield(self, p, val)
return p
-
- def post_build(self, pkt, pay):
- """DEV: called right after the current layer is build."""
- return pkt+pay
- def build_payload(self):
- return self.payload.build(internal=1)
+ def do_build_payload(self):
+ return self.payload.do_build()
- def build(self,internal=0):
+ def do_build(self):
if not self.explicit:
self = self.__iter__().next()
- pkt = self.do_build()
+ pkt = self.self_build()
for t in self.post_transforms:
pkt = t(pkt)
- pay = self.build_payload()
+ pay = self.do_build_payload()
p = self.post_build(pkt,pay)
- if not internal:
- pad = self.payload.getlayer(Padding)
- if pad:
- p += pad.build()
- p = self.build_done(p)
return p
+
+ def build_padding(self):
+ return self.payload.build_padding()
+
+ def build(self):
+ p = self.do_build()
+ p += self.build_padding()
+ p = self.build_done(p)
+ return p
+
+ def post_build(self, pkt, pay):
+ """DEV: called right after the current layer is build."""
+ return pkt+pay
def build_done(self, p):
return self.payload.build_done(p)
@@ -1029,8 +1036,12 @@ class NoPayload(Packet):
return ""
def __nonzero__(self):
return False
- def build(self, internal=0):
- return ""
+ def do_build(self):
+ return ""
+ def build(self):
+ return ""
+ def build_padding(self):
+ return ""
def build_done(self, p):
return p
def build_ps(self, internal=0):
@@ -1109,11 +1120,10 @@ class Raw(Packet):
class Padding(Raw):
name = "Padding"
- def build(self, internal=0):
- if internal:
- return ""
- else:
- return Raw.build(self)
+ def self_build(self):
+ return ""
+ def build_padding(self):
+ return self.load+self.payload.build_padding()
conf.raw_layer = Raw
if conf.default_l2 is None:
diff --git a/test/regression.uts b/test/regression.uts
index f5b5f732..069c617d 100644
--- a/test/regression.uts
+++ b/test/regression.uts
@@ -125,7 +125,7 @@ assert( _ == "abcdef" )
str(Raw("ABC")/Padding("abc")/Padding("def"))
assert( _ == "ABCabcdef" )
str(Raw("ABC")/Padding("abc")/Raw("DEF")/Padding("def"))
-assert( _ == "ABCabcDEFdef" )
+assert( _ == "ABCDEFabcdef" )
= Padding and length computation
IP(str(IP()/Padding("abc")))
--
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