Assignment 1 Solution

Programming Assignment (Turned in by one group mate)

First, it is assumed that by Labor day, 1) you have an engineering Unix account, 2) you can edit, 3) you can compile, and 4) you can execute C programs on the Unix (Tux) machines. You can use any personal computer or computing lab to remotely access the Engineering Unix machines.

Second, it is assumed that by Labor Day, you have your group partners. Past labor day, you will be on your own with a penalty of 5 points per lab: I want you to learn to work on a team and deal with human problems: pulling work out of people is a great skill.

Third, you sent us the extensions used by your preferred language if you are using a language other than Java or Python. If you do not send us by Labor Day these source extensions, Canvas will not allow you to submit your source code and you may face a late penalty.

Objectives:

Look at “How to get started?” at the very end of the lab.

Lab 1: Introduction to Socket Programming

First, find two group mates and sign up on Canvas to know your group ID (GID). You must implement and test your programming assignments on a machine (Tux machines) on the engineering network system. Your work will be tested and graded on an engineering machine (Tux machine).

I strongly advise you to read beej’s guide at :

http://beej.us/guide/bgnet/ (Simple, easy-to-understand tutorial)

FOR ALL THREE LABS IN THIS SEMESTER, you must use C for one of the programs and a different language for the second.

Example: if you write a client in C/C++, then you must use another language (Java, Python, or any other language available on the Tux machines) for the server.

Part A: Datagram socket programming

The objective is to design a Calculating Server (CS). This calculating server performs bitwise boolean and arithmetic computations requested by a client on 16 bit
integers. Your server must offer the following operations: 1) addition (+), 2) subtraction (-), 3) bitwise OR (|), 4) bitwise AND (&), 5) Shift Right (>>), and 6) Shift Left (<<).


A client request will have the following format:

Field


TML

Request ID

Op Code
Number Operands
Operand 1
Operand 2

Size (bytes)
1

1



1

1
2
2

Where
TML is the Total Message Length (in bytes) including TML. It is an integer
1)


representing the total numbers of bytes in the message.


2)
Request  ID  is  the  request  ID.  This  number  is  generated  by  the  client  to

differentiate  requests.  You  may  use  a  variable  randomly  initialized  and

incremented each time a request is sent.



3)
Op Code is a number specifying the desired operation following this table
Operation

+
-

|
&
>>

<<
~




OpCode

0
1

2
3
4


5
6




4)
Number Operands is the number of operands: 2 for (+, -, |, &) and shifts. It is 1

for ~ (NOT).










5)
Operand 1: this number is the first or unique operand for all operations.
6)
Operand 2: this number is the second operand for operations (+, -, |, &, <<, >>).

It is the number of bits to shift by for the shift operations. This operand does NOT

exist for the ~ (NOT) operation.




Operands are sent in the network byte order (i.e., big endian)

Below are two examples of requests

Request 1: suppose the Client requests to perform the operation 240 >> 4, i.e., shift the number 240 right by 4 bits (if this is the 7th request):

0x08    0x07    0x04    0x02    0x00    0xF0    0x00    0x04

Request 2: suppose the Client requests to perform the operation 240 – 160 (if this is the 9th request):

0x08
0x09
0x01
0x02
0x00
0xF0
0x00
0xA0


The Server will respond with a message with this format:

Total Message Length (TML)
Request ID
Error Code
Result
one byte
1 byte
1 byte
4 bytes

Where

    1) TML is the Total Message Length (in bytes) including TML. It is an integer representing the total numbers of bytes in the message.
    2) Request ID is the request ID. This number is the number that was sent as Request ID in the request sent by the client.
    3) Error Code is 0 if the request was valid, and 127 if the request was invalid.
    4) Result is the result of the requested operation.


In response to Request 1 below


0x08    0x07    0x04    0x02    0x00    0xF0    0x00    0x04

the server will send back:


0x07    0x07    0x00    0x00    0x00    0x00    0x0F


In response to Request 2,


0x08    0x09    0x01    0x02    0x00    0xF0    0x00    0xA0

the server would send back:


0x07    0x09    0x00    0x00    0x00    0x00    0x50


    a) Repetitive Server: Write a datagram Calculating Server (ServerUDP.c or ServerUDP.cpp) in C or C++. This server must respond to requests as described above. The server must run on port (10010+GID) and could run on any machine on the Internet. GID is your group ID. The server must accept a command line of the form: server portnumber where portnumber is the port where the server should be working. For example, if your Group ID (GID) is 13 then your server must listen on Port # 10023.

    b) Write a datagram client (ClientUDP.xxx) in any language other than C or C++ (readily available on Tux machines) you prefer which:
        i. Accepts as command line of the form: client servername PortNumber where servername is the server name and PortNumber is the port number of the server. Your program must prompt the user to ask for an Opcode, an Operand1 and if needed an Operand2 where OpCode is the opcode of the requested operation (See the opcode table). Operand1 and Operand2 (if applicable) are the operands. For each entry from the user, your program must perform the following operations:

        ii. forms a message as described above
        iii. Sends the message to the server and waits for a response
        iv. Prints all the message one byte at a time in hexadecimal (for debugging purpose)
        v. Prints out the response of the server in a manner convenient for a typical Facebook user: the request ID and the response
        vi. Prints out the round trip time (time between the transmission of the request and the reception of the response)
    vii. Prompt the user for a new request.








Part B: TCP socket programming

Repeat part A using TCP sockets to produce (ServerTCP.xxx, ClientTCP.c/cpp). The client must be written in C or C++. The server must be written in any language other than C or C++.



Grading:

    1) 25 points per program (2 clients and 2 servers)
    2) Code does not compile on Tux machine: 0% credit
    3) Code compiles on Tux machines but does work: 5% credit
    4) Code compiles and interacts correctly with counterpart from the same group: 60% credit
    5) Code compiles and interacts correctly with counterpart from other groups: 100% credit


“How to get started?”:

This is just an introduction to socket programming: I advise you to work ACTIVELY to implement these programs.

Step 1: download, compile, and execute Beej’s sample programs (UDP-client.c and UDP-server.c )

Step 2: get familiar with this code: study key socket programming calls/methods/functions
Step 3: improve the server to echo (send back) the string it receives.
Step 4: improve the client to receive the echo and to print it out.
Step 5: SAVE the improved versions (you may need to roll back to them if things turn bad)
Step 6: All you need now is “forming” your messages based on the specified format (lab 1 protocol).

For the TCP socket programming, redo Step 1-6 using Beej’s stream sample programs TCP-server.c and TCP-client.c.

Help Tools:

Besides this lab, I posted the following programs:
    1) TCP-server.c (Beej’s stream server)
    2) TCP-client.c (Beej’s stream client)
    3) UPD-server.c (Beej’s datagram server)
    4) UDP-client.c (Beej’s datagram client)
    5) TCPServerDisplay.c : this program is a modification of Beej’s TCP server: it takes as input a port number to run on and displays in hexadecimal what it receives.

    6) UDPServerDisplay.c : this program is a modification of Beej’s UDP server: it take as input a port number to run on and display in hexadecimal what it receives.
    7) packedStruct.c : this program demoes how to create a “packed” struct in C.



What to turn in?

To avoid a late submission, send us the extensions used for your source programs by Labor Day.

    1) Electronic copy of your report (standalone) and source code of your programs (standalone). IN ADDITION, All source codeprograms must be put in a zipped folder named lab1-name1-name2-name3 where name1, name2, and name3 are the last names of three teammates. Zip the folder and post it TOO on Canvas.
Make sure to submit separately (not inside the zipped folder) the report as a Microsoft or PDF file as well as the source code. A penalty of 25 points will be applied if these instructions are not followed.

    2) Your report must:

        a. state whether your code works

        b. Clearly explain how to compile and execute your code. If the TA needs your presence to compile and execute your code, then a 30% penalty will be applied.

        c. If needed, report/analyze (as appropriate) the results. The quality of analysis
and writing is critical to your grade.
Good writing and presentation are expected.

If the TA is unable to access/compile/execute your work based on your report, 30% will be applied.

If the turnin instructions are not followed, 25 pts will be deducted.