From 50915ed7aab90ea997e26ef42a5b1d646cc9d14f Mon Sep 17 00:00:00 2001
From: Phil <phil@secdev.org>
Date: Tue, 14 Dec 2010 13:48:43 +0100
Subject: [PATCH] Fix PadField.getfield() pad length calculation (ticket #358)
---
scapy/fields.py | 11 +++++++----
test/regression.uts | 7 +++++++
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/scapy/fields.py b/scapy/fields.py
index 914d320d..0bd480ac 100644
--- a/scapy/fields.py
+++ b/scapy/fields.py
@@ -158,14 +158,17 @@ class PadField:
self._align = align
self._padwith = padwith or ""
+ def padlen(self, flen):
+ return -flen%self._align
+
def getfield(self, pkt, s):
- x = self._fld.getfield(pkt,s)
- padlen = ((self._align - (len(x[1]) % self._align)) % self._align)
- return x[0][padlen:], x[1]
+ remain,val = self._fld.getfield(pkt,s)
+ padlen = self.padlen(len(s)-len(remain))
+ return remain[padlen:], val
def addfield(self, pkt, s, val):
sval = self._fld.addfield(pkt, "", val)
- return s+sval+struct.pack("%is" % (-len(sval)%self._align), self._padwith)
+ return s+sval+struct.pack("%is" % (self.padlen(len(sval))), self._padwith)
def __getattr__(self, attr):
return getattr(self._fld,attr)
diff --git a/test/regression.uts b/test/regression.uts
index 069c617d..ee7e7140 100644
--- a/test/regression.uts
+++ b/test/regression.uts
@@ -135,6 +135,13 @@ assert( _.len == 23 and len(_) == 26 )
IP(str(IP()/Raw("ABC")/Padding("abc")/Padding("def")))
assert( _.len == 23 and len(_) == 29 )
+= PadField test
+~ PadField padding
+
+class TestPad(Packet):
+ fields_desc = [ PadField(StrNullField("st", ""),4), StrField("id", "")]
+
+TestPad() == TestPad(str(TestPad()))
############
--
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