Server Side Scripting

1
Server Side Scripting

• CGI refresher
• Part of HTTP protocol set
• Non-platform dependent
• Different languages used to implement
• C / C
• Java
• Perl
• Python
• Tcl
• Rexx

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Server Side Scripting

• Perl (Practical Extraction Reporting Lang.)
• Created by Larry Wall in 1986 to create reports
• Building blocks
• numbers and strings
• You have won 5
• You have won prize

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Server Side Scripting

• Building Blocks (continued)
• scalars - individual piece of data - begins w/
• address 123 Woods Lane
• arrays - (list) - collection of scalars - begins
  w/ _at_
• _at_personalinfo (45, smith, 123 Woods Lane)
• hashes - (associative array) - begins w/
• collection of scalars in pairs - the first
  element in each pair is called the key and is the
  label for the second (value)
• allinfo (age, 45, name, smith)

4
Server Side Scripting

• Creating Perl CGI scripts
• Vi and Pico vs. Notepad
• Save w/ .cgi extension or .pl and put in cgi-bin
  subdirectory (/home/httpd/cgi-bin)
• All start w/ shebang line !
• Contains the location of the Perl interpreter
• To find on your server, type which perl at
  prompt
• ex. !/usr/bin/perl or !/usr/local/bin/perl
• Example - CS299perl1.cgi

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Server Side Scripting

• Launching your code
• perl -c filename (watch for post/get scripts)
• a href URL to Perl script or type w/in browser
• prompt - perl ltfilenamegt
• Form action

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Server Side Scripting

• Environement Variables
• Passed with each CGI connection
• Stored in ENV hash
• REQUEST_METHOD stores method
• QUERY_STRING stores GET data
• STDIN stores POST data
• Example - CS299perl3.cgi
• Parse subroutine needed to extract data
• browser ENVHTTP_USER_AGENT

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Server Side Scripting

• Creating output for browsers
• print Content-type text/html \n\n
• lttagsgt used within
• ltbrgt used for html, \n used for readability

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Server Side Scripting

• Email using Perl
• Using installed mail service (sendmail)
• Parse data w/in ENV hash
• open and pipe data to mail service
• Example - CS299perl5.cgi
• Network configuration on server
• default gateway set to 10.1.1.100
• DNS set to 172.16.17.16

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Server Side Scripting

• Cookies
• Setting a cookie
• Print Set-Cookie
• namevalue
• expiresDD-MMM-YY HHMMSS (in GMT)
• domainjuniata.edu
• path/cgi-bin/
• secure
• \n

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Server Side Scripting

• Cookies (continued)
• Expire date - specifies a date string that
  defines the valid life time of that cookie. If
  none given, the cookie expires when the user
  session ends.
• Domain - validates which domain can retrieve
  cookie. Can be absolute or tail match
• Path - used to specify the subset of URLs in a
  domain for which the cookie is valid. Must pass
  the domain first.
• Secure - must be sent via SSL

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Server Side Scripting

• Cookie examples
• setcookie.cgi
• updcookie.cgi
• delcookie.cgi
• getcookie.cgi
• Form examples
• cs299perl4.cgi
• cs299perl4a.cgi
• cs299perl4b.cgi

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Server Side Scripting

• Hands-on and helpful tips
• Complete cs299perl1.cgi and cs299perl3.cgi
• Location - /home/httpd/cgi-bin/
• reference http//10.1.1.x/cgi-bin/filename.cgi
• Permission errors? Chmod 755
• Configuration files (under /etc/httpd/conf)
• access.conf - virtual directory setup for cgi-bin
• srm.conf - script alias for cgi-bin and handler
  (.cgi .pl)
• stop and restart httpd service
• /etc/rc.d/init.d/httpd stop (start)