My Web Page

------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- G N A T . C G I -- -- -- -- S p e c -- -- -- -- $Revision: 1.9 $ -- -- -- Copyright (C) 2000 Ada Core Technologies, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ -- This is a package to interface a GNAT program with a Web server via the -- Common Gateway Interface (CGI). -- Other related packages are: -- GNAT.CGI.Cookie which deal with Web HTTP Cookies. -- GNAT.CGI.Debug which output complete CGI runtime environment -- Basically this package parse the CGI parameter which are a set of key/value -- pairs. It builds a table whose index is the key and provides some services -- to deal with this table. -- Example: -- Consider the following simple HTML form to capture a client name: -- -- -- -- My Web Page -- -- -- -- -- -- The following program will retrieve the client's name: -- with GNAT.CGI; -- procedure New_Client is -- use GNAT; -- procedure Add_Client_To_Database (Name : in String) is -- begin -- ... -- end Add_Client_To_Database; -- begin -- -- Check that we have 2 arguments (there is two inputs tag in -- -- the HTML form) and that one of them is called "client_name". -- if CGI.Argument_Count = 2 -- and the CGI.Key_Exists ("client_name") -- then -- Add_Client_To_Database (CGI.Value ("client_name")); -- end if; -- ... -- CGI.Put_Header; -- Text_IO.Put_Line ("< ... Ok ... >"); -- exception -- when CGI.Data_Error => -- CGI.Put_Header ("Location: /htdocs/error.html"); -- -- This returns the address of a Web page to be displayed -- -- using a "Location:" header style. -- end New_Client; -- Note that the names in this package interface have been designed so that -- they read nicely with the CGI prefix. The recommended style is to avoid -- a use clause for GNAT.CGI, but to include a use clause for GNAT. -- This package builds up a table of CGI parameters whose memory is not -- released. A CGI program is expected to be a short lived program and -- so it is adequate to have the underlying OS free the program on exit. package GNAT.CGI is Data_Error : exception; -- This is raised when there is a problem with the CGI protocol. Either -- the data could not be retrieved or the CGI environment is invalid. -- -- The package will initialize itself by parsing the runtime CGI -- environment during elaboration but we do not want to raise an -- exception at this time, so the exception Data_Error is deferred -- and will be raised when calling any services below (except for Ok). Parameter_Not_Found : exception; -- This exception is raised when a specific parameter is not found. Default_Header : constant String := "Content-type: text/html"; -- This is the default header returned by Put_Header. If the CGI program -- returned data is not an HTML page, this header must be change to a -- valid MIME type. type Method_Type is (Get, Post); -- The method used to pass parameter from the Web client to the -- server. With the GET method parameters are passed via the command -- line, with the POST method parameters are passed via environment -- variables. Others methods are not supported by this implementation. type Metavariable_Name is (Auth_Type, Content_Length, Content_Type, Document_Root, -- Web server dependant Gateway_Interface, HTTP_Accept, HTTP_Accept_Encoding, HTTP_Accept_Language, HTTP_Connection, HTTP_Cookie, HTTP_Extension, HTTP_From, HTTP_Host, HTTP_Referer, HTTP_User_Agent, Path, Path_Info, Path_Translated, Query_String, Remote_Addr, Remote_Host, Remote_Port, -- Web server dependant Remote_Ident, Remote_User, Request_Method, Request_URI, -- Web server dependant Script_Filename, -- Web server dependant Script_Name, Server_Addr, -- Web server dependant Server_Admin, -- Web server dependant Server_Name, Server_Port, Server_Protocol, Server_Signature, -- Web server dependant Server_Software); -- CGI metavariables that are set by the Web server during program -- execution. All these variables are part of the restricted CGI runtime -- environment and can be read using Metavariable service. The detailed -- meanings of these metavariables are out of the scope of this -- description. Please refer to http://www.w3.org/CGI/ for a description -- of the CGI specification. Some metavariables are Web server dependant -- and are not described in the cited document. procedure Put_Header (Header : String := Default_Header; Force : Boolean := False); -- Output standard CGI header by default. The header string is followed by -- an empty line. This header must be the first answer sent back to the -- server. Do nothing if this function has already been called and Force -- is False. function Ok return Boolean; -- Returns True if the CGI environment is valid and False otherwise. -- Every service used when the CGI environment is not valid will raise -- the exception Data_Error. function Method return Method_Type; -- Returns the method used to call the CGI. function Metavariable (Name : Metavariable_Name; Required : Boolean := False) return String; -- Returns parameter Name value. Returns the null string if Name -- environment variable is not defined or raises Data_Error if -- Required is set to True. function Metavariable_Exists (Name : Metavariable_Name) return Boolean; -- Returns True if the environment variable Name is defined in -- the CGI runtime environment and False otherwise. function URL return String; -- Returns the URL used to call this script without the parameters. -- The URL form is: http://[:] function Argument_Count return Natural; -- Returns the number of parameters passed to the client. This is the -- number of input tags in a form or the number of parameters passed to -- the CGI via the command line. --------------------------------------------------- -- Services to retrieve key/value CGI parameters -- --------------------------------------------------- function Value (Key : String; Required : Boolean := False) return String; -- Returns the parameter value associated to the parameter named Key. -- If parameter does not exist, returns an empty string if Required -- is False and raises the exception Parameter_Not_Found otherwise. function Value (Position : Positive) return String; -- Returns the parameter value associated with the CGI parameter number -- Position. Raises Parameter_Not_Found if there is no such parameter -- (i.e. Position > Argument_Count) function Key_Exists (Key : String) return Boolean; -- Returns True if the parameter named Key existx and False otherwise. function Key (Position : Positive) return String; -- Returns the parameter key associated with the CGI parameter number -- Position. Raises the exception Parameter_Not_Found if there is no -- such parameter (i.e. Position > Argument_Count) generic with procedure Action (Key : String; Value : String; Position : Positive; Quit : in out Boolean); procedure For_Every_Parameter; -- Iterate through all existing key/value pairs and call the Action -- supplied procedure. The Key and Value are set appropriately, Position -- is the parameter order in the list, Quit is set to True by default. -- Quit can be set to False to control the iterator termination. private function Decode (S : String) return String; -- Decode Web string S. A string when passed to a CGI is encoded, -- this function will decode the string to return the original -- string's content. Every triplet of the form %HH (where H is an -- hexadecimal number) is translated into the character such that: -- Hex (Character'Pos (C)) = HH. end GNAT.CGI;