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

diff --cc a2/1cases.tex
index d77edb7,da3a34b..1bfdc39
--- 1/a2/1cases.tex
--- 2/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