Lab 8 – Sockets Solution

Introduction




Lab 8 introduces you to network communications in Perl. Your simple Perl script will contact a given server on a given port number (using protocol TCP), read the first line sent by the server and display it on the terminal.




Requirements




Your Perl script shall be named socket.pl and be marked executable.










`Usage: ./socket.pl HOSTNAME SOCKETNUMBER`







Example







./socket.pl icarus.cs.weber.edu 22




Issue an appropriate message to STDERR and exit with a non-zero return code if it fails to connect to the provided socket at the provided host.




Issue a usage message to STDERR and exit(1) if the socket parameters are not provided.







HOSTNAME can be a name such as www.google.com or an IP address such as 137.65.1.1







Test your script on icarus with ./socket.pl localhost 25 which should print something like







icarus.users.weber.edu ESMTP Postfix (Ubuntu) . Print just one line and exit(0) . Your script must not hang or run more than a few seconds unless it times out



attempting to connect to an unknown host or an invalid socket number.




It is acceptable to use die() , but warning: your return codes will be unpredictable.







Helpful Hints




Refer to the simple client in perlipc.pdf (located in the Reference folder) as a guide. Use the socket() call to create a connection to the requested port on the server Read just one line and exit. If you loop (as in the simple client) your script may hang. Use print to output the received line to STDOUT




$ARGV[] contains the commandline arguments. $ARGV[0] is the first argument (hostname), etc. $#ARGV is the index of the last item in $ARGV







Clone your private repo on github.com




In the assignment module in Canvas, find the link to the Canvas page entitled "Clone your Lab 8 Repo", click on it and follow the instructions.

Copy your private repo down to icarus







BASH




git clone https://github.com/cowancs3030spring19/lab8-YOURGITHUBUSERNAME




cd lab8-YOURGITHUBUSERNAME







Write and test socket.pl




Fire up your favorite text editor, and begin with your header:










#!/usr/bin/perl







TEXT



(Your name)



Lab 8 - Sockets



CS 3030 - Scripting Languages



(Add your amazing, perfect code here)







Run cucumber to check your progress










./cucumber -s







Submit your assignment code for grading




Remember, you must push your script in your private repo to github.com to receive any points, for all assignments in this course.









BASH




git add socket.pl




git commit -m"COMMIT MESSAGE"




git push origin master







Files created for this lab




socket.pl




Grading




Here is how you earn points for this assignment:










































Cowan 03-21-2019 07:39 PM 2




FEATURES
POINTS










Must-Have Features














Script is named correctly and found in its proper place in your private repo
5












Script is executable
5












Required Features














Script prints a “Usage:” statement and exits rc=1 if there are not exactly two
5




commandline parameters














Script exits rc=0 on successful completion
5












Script writes error messages only to STDERR
10












Script prints one line from localhost
20












Script reads from a port from a named host (e.g. weber.edu)
30












Script reads from a port from an external host (not localhost)
30












Script return error message and rc!=0 on invalid hostname
20












Script return error message and rc!=0 on invalid port
20












Grand Total
150




































































































Cowan 03-21-2019 07:39 PM
3