(********************************************************************************************
** PROGRAM : cgiform
** VERSION : 1.0.0
** DESCRIPTION : Demonstrates how to process HTML forms in CGI programs.
** AUTHOR : Stuart King
** COPYRIGHT : Copyright (c) Irie Tools, 2002. All Rights Reserved.
** NOTES :
** This sample program is distributed with Irie Pascal, and was written to illustrate
** how to process HTML forms. To make best use of this sample you should have a basic
** understanding of Pascal as well as a basic understanding of the Common Gateway Interface
** (CGI).
**
** HTML forms provide a way for websites to receive input from visitors, and to process
** this input in some way. HTML forms contain different kinds of input elements in order
** to conveniently receive different kinds of visitor input. The most common kinds of
** input elements are:
** 1. One line text entry boxes
** 2. Multi-line text entry boxes
** 3. Checkboxes
** 4. Radio buttons
** 5. Hidden fields
** 6. Selection lists (Drop-down menus and List boxes).
** 7. Reset button
** 8. Submit button
**
** HTML forms have action attributes that indicate what should happen when the submit
** button is clicked. It is very common for the action attribute to point at the URL of
** a CGI program. In this case when the submit button is pressed the CGI program is executed
** and the form's input is passed to the program for processing. Each input element in the
** form has a name and the form's input is sent to the CGI program in the form of name/value
** pairs, where the values are the input received by the input elements.
**
** What this program actually does is retrieve any form input passed to it. If it receives
** form input then this program just displays the name/value pairs, along with a link that
** can be used to execute the program again. If the program does not receive any form input
** then it displays a form with a variaty of input elements. The form's action element points
** back to the program, so that the program will receive the input from the form when the
** submit button is pressed.
**********************************************************************************************)
program cgiform;
const
MAX_BUFFER = 8000;
MAX_NAME = 20;
MAX_VALUE = 400;
type
positive = 0..maxint;
BufferType = string[MAX_BUFFER];
NameValuePair = record
Name : string[MAX_NAME];
Value : string[MAX_VALUE]
end;
var
buffer : BufferType;
NameValuePairs : list of NameValuePair;
ScriptName : filename;
function EscapeCharacters(s : string) : string; forward;
//PURPOSE: Initializes the program
//NOTES:
// Initializes the list that will be used to store the name/value pairs
//passed to the program. The program also retrieves it's name so that it can
//refer to itself in the generated response.
procedure Initialize;
begin (* Initialize *)
new(NameValuePairs);
ScriptName := getenv('SCRIPT_NAME');
end; (* Initialize *)
//PURPOSE: Retrieves the information passed to the CGI applications.
//GLOBAL(s) - buffer - Used to store the GET or POST information passed to the CGI program
procedure GetCGIData;
var
RequestMethod : string;
//PURPOSE: Retrieves information sent to by a GET request (i.e. in the QUERY_STRING
// environment variable).
procedure GetRequest;
begin (* GetRequest *)
buffer := getenv('QUERY_STRING')
end; (* GetRequest *)
//PURPOSE: Retrieves information sent to by a POST request (i.e. through the standard
// input stream, with the length of the data in the environment variable
// CONTENT_LENGTH).
procedure PostRequest;
var
len, i : positive;
err : integer;
ContentLength : string;
c : char;
begin (* PostRequest *)
buffer := '';
ContentLength := getenv('CONTENT_LENGTH');
if ContentLength <> '' then
val(ContentLength, len, err)
else
len := 0;
if len <= MAX_BUFFER then
for i := 1 to len do
begin
read(c);
buffer := buffer + c
end
end; (* PostRequest *)
begin (* GetCGIData *)
RequestMethod := getenv('REQUEST_METHOD');
if RequestMethod = 'GET' then
GetRequest
else
PostRequest
end; (* GetCGIData *)
//PURPOSE: Process the data passed to the program.
//NOTES: This is the main part of the program. After retreiving
// the information passed to the program this procedure is
// called to perform the required processing.
procedure ProcessCGIData;
var
i, num, p : integer;
EncodedVariable, DecodedVariable, name, value : string;
//PURPOSE: Processes the named value pairs sent with the GET or POST request.
// Which in this case is the information entered by the user about the
// cookie to add or delete.
//ARGUMENT(s): name - name part of the name/value pair
// value - value part of name/value pair
//NOTES:
// The information entered by the user is sent as name/value pairs (i.e. name-value)
//with the name part being the name of the form element holding the information and
//the value part being the actual information held by the form element.
procedure ProcessNameValuePair(var name, value : string);
var
pair : NameValuePair;
begin (* ProcessNameValuePair *)
pair.name := name;
pair.value := value;
insert(pair, NameValuePairs);
end; (* ProcessNameValuePair *)
begin (* ProcessCGIData *)
//Retrieve each name/value pair from the form and processes them.
num := CountWords(buffer, '&');
for i := 1 to num do
begin
EncodedVariable := CopyWord(buffer, i, '&');
DecodedVariable := URLDecode(EncodedVariable);
p := pos('=', DecodedVariable);
if p > 0 then
begin
name := lowercase(trim(copy(DecodedVariable, 1, p-1)));
value := trim(copy(DecodedVariable, p+1));
ProcessNameValuePair(name, value);
end
end;
end; (* ProcessCGIData *)
//PURPOSE: Generates the response to send back to the browser.
procedure GenerateResponse;
procedure GenerateHeader;
begin (* GenerateHeader *)
//Generate the response headers (including the blank line at the end).
writeln('content-type: text/html');
writeln;
writeln('<html>');
writeln('<head>');
writeln('<title>Irie Pascal sample CGI application</title>');
writeln('<h1>CGIFORM</h1>');
writeln('<h2>This program displays the data entered into a form.</h2>');
writeln('</head>');
writeln(' <hr>');
end; (* GenerateHeader *)
procedure GenerateBody;
procedure WriteForm;
begin (* WriteForm *)
writeln('<form method="POST" action="', ScriptName, '">');
writeln(' <h2>One Line Text Box:</h2>');
writeln(' <p>OneLine <input type="text" name="OneLine" size="20"></p>');
writeln(' <hr>');
writeln(' <h2>Scrolling Text Box:</h2>');
writeln(' <p>Scrolling <textarea rows="2" name="Scrolling" cols="20"></textarea></p>');
writeln(' <hr>');
writeln(' <h2>Check Boxes</h2>');
writeln(' <p>Box1 <input type="checkbox" name="Box1" value="1">');
writeln(' Box2 <input type="checkbox" name="Box2"');
writeln(' value="1"></p>');
writeln(' <p>Box3 <input type="checkbox" name="Box3" value="1">');
writeln(' Box4 <input type="checkbox" name="Box4"');
writeln(' value="1"></p>');
writeln(' <hr>');
writeln(' <h2>Radio Buttons</h2>');
writeln(' <p>Radio1 <input type="radio" value="1" checked name="Radio1">');
writeln(' Radio2 <input type="radio" name="Radio2"');
writeln(' value="2"></p>');
writeln(' <p>Radio3 <input type="radio" name="Radio3" value="3">');
writeln(' Radio4 <input type="radio" name="Radio4"');
writeln(' value="4"></p>');
writeln(' <hr>');
writeln(' <h2>Drop-Down Menu</h2>');
writeln(' <p>DropDown <select name="DropDown" size="1">');
writeln(' <option value="Choice1">Choice1</option>');
writeln(' <option value="Choice2">Choice2</option>');
writeln(' <option value="Choice3">Choice3</option>');
writeln(' <option value="Choice4">Choice4</option>');
writeln(' <option value="Choice5">Choice5</option>');
writeln(' <option value="Choice6">Choice6</option>');
writeln(' </select></p>');
writeln(' <hr>');
writeln(' <p><input type="submit" value="Submit" name="Submit"><input type="reset" value="Reset"');
writeln(' name="Reset"></p>');
writeln('</form>');
end; (* WriteForm *)
procedure WriteFormData;
var
pair : NameValuePair;
i : positive;
begin (* WriteFormData *)
writeln('<h1>Form Data</h1>');
for i := 1 to length(NameValuePairs) do
begin
pair := NameValuePairs[i];
writeln('<h3>', EscapeCharacters(pair.name), ' = ', EscapeCharacters(pair.value), '</h3>');
end;
writeln('<hr>');
writeln('<p>Click <a href="', ScriptName, '">here</a> to go back to the form.</p>');
end; (* WriteFormData *)
begin (* GenerateBody *)
writeln('<body>');
if length(NameValuePairs) = 0 then
begin
//Generate the HTML for the form
WriteForm;
end
else
begin
//Generate the HTML that displays the form data
WriteFormData;
end;
writeln('</body>');
end; (* GenerateBody *)
procedure GenerateFooter;
begin (* GenerateFooter *)
writeln('</html>');
end; (* GenerateFooter *)
begin (* GenerateResponse *)
GenerateHeader;
GenerateBody;
GenerateFooter;
end; (* GenerateResponse *)
procedure Shutdown;
begin (* Shutdown *)
dispose(NameValuePairs);
end; (* Shutdown *)
//*************************************************************************
//PURPOSE: This function converts certain characters that have a
// special meaning in HTML documents to their HTML representation.
//ARGUMENT(s): s - The string to be escaped.
//RETURNS: The string with all special characters escaped.
//NOTES: The characters converted are < > "
function EscapeCharacters;
const
LessThanChar = '<';
GreaterThanChar = '>';
QuoteChar = '"';
HTMLLessThan = '<';
HTMLGreaterThan = '>';
HTMLQuote = '"';
var
i : positive;
procedure ReplaceChar(var strBuffer : string; strReplace : string; i : positive);
begin (* ReplaceChar *)
delete(strBuffer, i, 1);
insert(strReplace, strBuffer, i)
end; (* ReplaceChar *)
begin (* EscapeCharacters *)
repeat
i := pos(LessThanChar, s, 1);
if i > 0 then
ReplaceChar(s, HTMLLessThan, i)
until i = 0;
repeat
i := pos(GreaterThanChar, s, 1);
if i > 0 then
ReplaceChar(s, HTMLGreaterThan, i)
until i = 0;
repeat
i := pos(QuoteChar, s, 1);
if i > 0 then
ReplaceChar(s, HTMLQuote, i)
until i = 0;
EscapeCharacters := s;
end; (* EscapeCharacters *)
begin
Initialize;
GetCGIData;
ProcessCGIData;
GenerateResponse;
Shutdown;
end.
