CGI programming

1
CGI programming

• Peter Verhás
• January 2002

2
What this tutorial is about

• Introduction to CGI programming
• Using ScriptBasic
• Simple to program
• Simple to setup on Linux or any Win
• Prerequisite understanding web architecture

3
How to setup ScriptBasic web test environment?

• Install ScriptBasic
• Edit the configuration file
• scriba.conf.lsp
• Compile it using cftc.exe
• Start sbhttpd
• Start your browser
• (Well, this is not true CGI, but does not matter)

4
How is CGI Working?

• A new process on the web server
• The CGI process reads stdin and environment
  variables
• It writes the stdout

5
Hello World!

• ! /usr/bin/scriba -c
• include cgi.bas
• cgiHeader 200,"text/html"
• cgiFinishHeader
• print """ltHTMLgt
• ltBODYgt
• Hello World!
• lt/BODYgt
• lt/HTMLgt
• """
• stop

6
Which Environment Variables?

• Important environment variables (from the http
  header)
• REMOTE_ADDR 127.0.0.1
• REQUEST_METHOD GET
• REMOTE_HOST localhost
• HTTP_USER_AGENT Mozilla/4.0
• HTTP_ACCEPT /
• HTTP_CONNECTION Keep-Alive
• HTTP_ACCEPT_LANGUAGE hu
• SCRIPT_NAME test.bas
• SERVER_NAME localhost
• SERVER_PORT 80
• CONTENT_LENGTH 0
• QUERY_STRING qverhE1s2BCGI
• PATH_TRANSLATED /home/httpd/cgi-bin/test.bas

7
Print Out Environment Variables

• ! /usr/bin/scriba -c
• include cgi.bas
• cgiHeader 200,"text/html"
• cgiFinishHeader
• print """ltHTMLgt
• ltBODYgt
• ltPREgt
• """
• i 0
• while IsDefined( Environ(i) )
• print i," ",Environ(i),"\n"
• i i1
• wend
• print """lt/PREgt
• lt/BODYgt
• lt/HTMLgt
• """
• stop

8
What is in the QUERY_STRING?

• Anything that the browser sends
• A FORM parameters coded
• parametervalue pairs joined with
• Space replaced by
• Special characters XX hexa encoded

9
Print Out QUERY_STRING

• ! /usr/bin/scriba -c
• include cgi.bas
• cgiHeader 200,"text/html"
• cgiFinishHeader
• print """ltHTMLgt
• ltBODYgt
• ltPREgt
• """
• print Environ("QUERY_STRING")
• print """lt/PREgt
• lt/BODYgt
• lt/HTMLgt
• """
• stop

10
Getting Parameters

• ! /usr/bin/scriba -c
• include cgi.bas
• cgiHeader 200,"text/html"
• cgiFinishHeader
• print """ltHTMLgt
• ltBODYgt
• ltPREgt
• """
• print cgiGetParam("apple")
• print """lt/PREgt
• lt/BODYgt
• lt/HTMLgt
• """
• stop

11
Getting Parameters

• ! /usr/bin/scriba -c
• include cgi.bas
• cgiHeader 200,"text/html"
• cgiFinishHeader
• print """ltHTMLgt
• ltBODYgt
• ltPREgt
• ltFORM METHOD"POST"gt
• ltINPUT TYPE"TEXT" NAME"apple"gt
• lt/FORMgt
• """
• print cgiPostParam("apple")
• print """lt/PREgt
• lt/BODYgt
• lt/HTMLgt
• """
• stop

12
Handling Cookies
13
File Upload
14
User Authentication
15

• Thank you for your attention.