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CGI Scripts

CGI Scripts. GET. Form data forms query string and is appended to the URL of the script Can be accessed by using the environment variable QUERY_STRING Browser or server may truncate data that exceeds an arbitrary number of characters. GET. GET request by client

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CGI Scripts

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  1. CGI Scripts

  2. GET • Form data forms query string and is appended to the URL of the script • Can be accessed by using the environment variable QUERY_STRING • Browser or server may truncate data that exceeds an arbitrary number of characters CGI Scripts

  3. GET • GET request by client GET /cgi-bin/prog.pl?name= Bill+age=29 HTTP/1.0 Accept: www/source Accept: text/html Accept: text/plain User-Agent: Lynx/2.4 libwww/2.14 CGI Scripts

  4. GET • Can access CGI program with a query without using a form <a href="/cgi-bin/prog.pl?name= Bill+age=29">CGI program</a> • Can also send extra path information • Usually file name <a href="/cgi-bin/prog.pl/name= Bill+age=29">CGI program</a> CGI Scripts

  5. POST • Query length is unlimited • Script reads from standard input • Can't create canned queries CGI Scripts

  6. POST POST /cgi-bin/prog.pl HTTP/1.0 Accept: www/source Accept: text/html Accept: text/plain User-Agent: Lynx/2.4 libww/2.14 Content-type: application/x-www-form-urlencoded Content-length: 22 user=Larry+Bird&age=30 CGI Scripts

  7. Decoding Form Data • Determine request protocol by checking the REQUEST_METHOD environment variable • GET or POST • One script can work for both methods • If the protocol is GET, read query string from QUERY_STRING and/or the extra path information from PATH_INFO CGI Scripts

  8. Decoding Form Data • If the protocol is POST, determine the size of the request using CONTENT_LENGTH and read that amount of data from the standard input • Split the query string on the '&' character, which separates key-value pairs • The format is key=value&key=value... CGI Scripts

  9. Decoding Form Data • Decode the hexadecimal and '+' characters in each key-value pair • Create a key-value table with the key as the index CGI Scripts

  10. Examples • Using forms with POST • Plain text • Guestbook • http://jupiter.cs.wayne.edu/~grosky/user-cgi/guestbook.pl?add using the GET method, will present a form for you to enter information CGI Scripts

  11. Examples • Guestbook • http://jupiter.cs.wayne.edu/~grosky/user-cgi/guestbook.pl using the GET method, will display the actual guestbook file [guestbook.htm] • Can open guestbook file directly by accessing http://jupiter.cs.wayne.edu/ ~grosky/CSC691/CGIScripts/ Guestbook/guestbook.htm CGI Scripts

  12. Examples • Guestbook • When form is submitted using the POST method, this program decodes the information and outputs a thank-you message CGI Scripts

  13. Examples • Survey • http://jupiter.cs.wayne.edu/~grosky/user-cgi/shopping.pl/start.htm • http://jupiter.cs.wayne.edu/ ~grosky/CSC691/CGIScripts/Hidden Fields/start.htm CGI Scripts

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