Description
This assignment provides all students an opportunity to work through the standard procedures for
developing, executing and testing C socket programs on a Linux system. The assignment is broken up
into two distinct programming assignments: the basic TCP Echo Server and the enhanced TCP Echo
Server.
Basic TCP Echo Server and Client 4 points
The first task is to utilize any available version of the TCP Echo Client and TCP Echo Server that you
prefer. It can be essentially a copy of the programs in the D&C textbook or any other textbook (your
comments must indicate the source). The required steps in the basic assignment are:
1. Write the client program and the server program that will execute on CCC Linux machines using
your favorite editor.
2. Create and use a make file to build, test and debug both programs.
3. Create a README plain text file to assist in the grading of program 0.
4. Tar the two source programs, the make file and the README file into a single tar file for
submission.
5. Use the Unix version of turnin to submit the tarred file for grading.
The basic assignment is to write both a TCP Echo Client and a TCP Echo Server in C or C++ using Unix
socket commands. The client and server implement the echo protocol while running on different CCC
Linux machines and communicating with each other using TCP.
The Basic Echo Client
The basic Echo client connects to the basic Echo server and sends its data to the server. The data that
the client sends is a string provided as the second client command-line argument. The basic Echo
client prints the single string of data sent back by the Echo server.
An example of the form of the command line and the resultant print line for the basic Echo client are:
./my_EchoClient 169.1.2.3 “echo this string!!”
Client received: echo this string!!
169.1.2.3 is the first argument is the dotted-quad notation IP address of the Echo server.
my this should be replaced by the initials of the program author .
CS3516 Computer Networks A15
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The basic Echo client accepts strings of length 1 to 32 bytes inclusive and prints out an error message
for any out-of-range input string.
The Basic Echo Server
After connecting to the basic Echo client, the basic Echo server (which is started first) simply echoes
the string it receives as a TCP packet back to the Echo client, disconnects and terminates.
The Enhanced TCP Echo Server and Client 4 points
The second component of program 0 is to enhance the basic Echo Client and Server to echo more than
a single input string.
The Enhanced Echo Client
The enhance echo client receives up to five strings on the command. The form of the command line
and the resultant print lines for the enhanced Echo client are:
./my_EnhancedEchoClient ServerMachine “string 1” “string 2” “string 3” “string 4” “string 5”
EnhancedClient received: string 1
EnhancedClient received: string 4
EnhancedClient received: string 3
EnhancedClient received: string 4
EnhancedClient received: string 5
EnhancedClient: done
[1 pt] The enhanced Echo client receives the name of the computer where the server is running (e.g.,
CCCWORK2) as its first command-line argument and uses a Linux system call to convert the server
name to the associated server IP address.
[2.5 pts] The other enhancement for both the Echo client and the Echo server permits the number of
strings echoed to vary from one to five. The enhanced Echo client sends a series of data strings (one
per TCP packet) to the enhanced Echo server. The enhanced Echo client prints out each data string
sent back by the enhanced Echo server. Once the enhanced Echo client has sent and printed all the
echoed strings, it sends one additional TCP packet containing the two ASCII bytes DLE ETX. Once the
enhanced Echo client receives the echoed DLE ETX bytes, it prints out a done message, disconnects
and terminates.
[0.5 pts] The enhanced Echo client accepts strings of length 1 to 12 bytes inclusive and prints out an
error message for any out-of-range input string. Any out-of-range string is not transmitted, echoed or
printed. The Echo client then processes the next string (if any).
CS3516 Computer Networks A15
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The Enhanced Echo Server
The enhanced Echo server runs in a loop accepting up to five strings from the enhanced Echo client as
five TCP packets. When the enhanced Echo server receives a packet containing the two ASCII bytes
DLE ETX, it echoes this packet back to the client and prints out a message of the form:
Enhanced Echo Server sent n strings to the Enhanced Echo Client.
where n is the number of strings echoed by the server prior to receiving the DLE ETX.
The enhanced Echo server then disconnects and terminates.
What to turn in for Program 0
Turn in Program 0 using the turnin program on the CCC machines. You must turn in a tarred file that
includes: your source code files, two make files, a single README file and a sample output file from a
test run for both the basic and enhanced assignments. Your tarred file should include separate source
files and make files for both the basic and the enhanced Echo Client and Server. The make files should
include the ability to cleanup leftover output and intermediate files between compile and execution
cycles. The README file provides any information to help the testing and grading of your Echo Client
and Echo Server on CCC machines. If you did not fully complete either assigned task, the role of the
README file is to honestly indicate to the grader those components of the assignment you have
working and those components that you are turning in that still do not work completely .
