From: pimjager <pim@pimjager.nl>
Date: Wed, 11 Nov 2015 13:48:31 +0000 (+0100)
Subject: Merge branch 'master' of https://github.com/dopefishh/tt2015
X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=68e3344a6e17ea512f3c04cc9d25951e3cff530a;p=tt2015.git

Merge branch 'master' of https://github.com/dopefishh/tt2015
---

68e3344a6e17ea512f3c04cc9d25951e3cff530a
diff --cc a2/1cases.tex
index d77edb7,da3a34b..1bfdc39
--- a/a2/1cases.tex
+++ b/a2/1cases.tex
@@@ -113,32 -110,22 +110,41 @@@ these partitions are given
  	\item Bits flipped in \emph{payload}
  		\begin{enumerate}
  			\item Correct payload
 -			\item Payload with even number of bits flipped
 +			\item Payload with bit flips 
  			\item Payload with odd number of bits flipped
  		\end{enumerate}
- 	\item Correct or Incorrect \emph{checksum}
- 	\item Packets received in or out of order, or missing packets
+ 	\item \emph{checksum}
+ 		\begin{enumerate}
+ 			\item Correct
+ 			\item Incorrect
+ 		\end{enumerate}
+ 	\item Packet order
+ 		\begin{enumerate}
+ 			\item Correct
+ 			\item Out of order
+ 			\item Missing packets
+ 		\end{enumerate}
  \end{enumerate}
  
 +These partitions were chosen since they correspond to key parts of the TCP
 +specification. 
 +
 +TCP segments are send over a TCP connection from a \emph{source} to a \emph{destination port}. Therefore segments which are received which have a 
 +source or destination port set to an incorrect value should not be regarded
 +as segments belonging to the connection. 
 +
 +TCP uses a \emph{checksum} to catch any error introduced in headers, when this
 +checksum does not match the actual computed checksum the packet should be
 +disregarded.
 +
 +The TCP checksum is also an inherently weak one, as it is simply the 
 +bitwise negation of the addition in ones complement arithmetic 
 +of all 16 bit words in the header and data of the segment (excluding the
 +header). Therefore any bit error where the ones complement value of one word
 +increases by one, and the value of another decreases by one, is undetected. 
 +The SUT should exhibit the same behavior and accept packets where these type
 +of bit error occur.
 +
  \textbf{hier iets over waarom deze partities relevant zijn! Waarom odd en 
  even number of bits flipped bijv interessant?}
  \bigskip