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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             G N A T . C G I                              --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--                      Copyright (C) 2001-2010, AdaCore                    --

--                                                                          --

-- 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 3,  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.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Ada.Text_IO;

with Ada.Strings.Fixed;

with Ada.Characters.Handling;

with Ada.Strings.Maps;

with GNAT.OS_Lib;

with GNAT.Table;

package body GNAT.CGI is

   use Ada;

   Valid_Environment : Boolean := True;

   --  This boolean will be set to False if the initialization was not

   --  completed correctly. It must be set to true there because the

   --  Initialize routine (called during elaboration) will use some of the

   --  services exported by this unit.

   Current_Method : Method_Type;

   --  This is the current method used to pass CGI parameters

   Header_Sent : Boolean := False;

   --  Will be set to True when the header will be sent

   --  Key/Value table declaration

   type String_Access is access String;

   type Key_Value is record

      Key   : String_Access;

      Value : String_Access;

   end record;

   package Key_Value_Table is new Table (Key_Value, Positive, 1, 1, 50);

   -----------------------

   -- Local subprograms --

   -----------------------

   procedure Check_Environment;

   pragma Inline (Check_Environment);

   --  This procedure will raise Data_Error if Valid_Environment is False

   procedure Initialize;

   --  Initialize CGI package by reading the runtime environment. This

   --  procedure is called during elaboration. All exceptions raised during

   --  this procedure are deferred.

   --------------------

   -- Argument_Count --

   --------------------

   function Argument_Count return Natural is

   begin

      Check_Environment;

      return Key_Value_Table.Last;

   end Argument_Count;

   -----------------------

   -- Check_Environment --

   -----------------------

   procedure Check_Environment is

   begin

      if not Valid_Environment then

         raise Data_Error;

      end if;

   end Check_Environment;

   ------------

   -- Decode --

   ------------

   function Decode (S : String) return String is

      Result : String (S'Range);

      K      : Positive := S'First;

      J      : Positive := Result'First;

   begin

      while K <= S'Last loop

         if K + 2 <= S'Last

           and then  S (K) = '%'

           and then Characters.Handling.Is_Hexadecimal_Digit (S (K + 1))

           and then Characters.Handling.Is_Hexadecimal_Digit (S (K + 2))

         then

            --  Here we have '%HH' which is an encoded character where 'HH' is

            --  the character number in hexadecimal.

            Result (J) := Character'Val

              (Natural'Value ("16#" & S (K + 1 .. K + 2) & '#'));

            K := K + 3;

         --  Plus sign is decoded as a space

         elsif S (K) = '+' then

            Result (J) := ' ';

            K := K + 1;

         else

            Result (J) := S (K);

            K := K + 1;

         end if;

         J := J + 1;

      end loop;

      return Result (Result'First .. J - 1);

   end Decode;

   -------------------------

   -- For_Every_Parameter --

   -------------------------

   procedure For_Every_Parameter is

      Quit : Boolean;

   begin

      Check_Environment;

      for K in 1 .. Key_Value_Table.Last loop

         Quit := False;

         Action (Key_Value_Table.Table (K).Key.all,

                 Key_Value_Table.Table (K).Value.all,

                 K,

                 Quit);

         exit when Quit;

      end loop;

   end For_Every_Parameter;

   ----------------

   -- Initialize --

   ----------------

   procedure Initialize is

      Request_Method : constant String :=

                         Characters.Handling.To_Upper

                           (Metavariable (CGI.Request_Method));

      procedure Initialize_GET;

      --  Read CGI parameters for a GET method. In this case the parameters

      --  are passed into QUERY_STRING environment variable.

      procedure Initialize_POST;

      --  Read CGI parameters for a POST method. In this case the parameters

      --  are passed with the standard input. The total number of characters

      --  for the data is passed in CONTENT_LENGTH environment variable.

      procedure Set_Parameter_Table (Data : String);

      --  Parse the parameter data and set the parameter table

      --------------------

      -- Initialize_GET --

      --------------------

      procedure Initialize_GET is

         Data : constant String := Metavariable (Query_String);

      begin

         Current_Method := Get;

         if Data /= "" then

            Set_Parameter_Table (Data);

         end if;

      end Initialize_GET;

      ---------------------

      -- Initialize_POST --

      ---------------------

      procedure Initialize_POST is

         Content_Length : constant Natural :=

                            Natural'Value (Metavariable (CGI.Content_Length));

         Data : String (1 .. Content_Length);

      begin

         Current_Method := Post;

         if Content_Length /= 0 then

            Text_IO.Get (Data);

            Set_Parameter_Table (Data);

         end if;

      end Initialize_POST;

      -------------------------

      -- Set_Parameter_Table --

      -------------------------

      procedure Set_Parameter_Table (Data : String) is

         procedure Add_Parameter (K : Positive; P : String);

         --  Add a single parameter into the table at index K. The parameter

         --  format is "key=value".

         Count : constant Positive :=

                   1 + Strings.Fixed.Count (Data, Strings.Maps.To_Set ("&"));

         --  Count is the number of parameters in the string. Parameters are

         --  separated by ampersand character.

         Index : Positive := Data'First;

         Amp   : Natural;

         -------------------

         -- Add_Parameter --

         -------------------

         procedure Add_Parameter (K : Positive; P : String) is

            Equal : constant Natural := Strings.Fixed.Index (P, "=");

         begin

            if Equal = 0 then

               raise Data_Error;

            else

               Key_Value_Table.Table (K) :=

                 Key_Value'(new String'(Decode (P (P'First .. Equal - 1))),

                            new String'(Decode (P (Equal + 1 .. P'Last))));

            end if;

         end Add_Parameter;

      --  Start of processing for Set_Parameter_Table

      begin

         Key_Value_Table.Set_Last (Count);

         for K in 1 .. Count - 1 loop

            Amp := Strings.Fixed.Index (Data (Index .. Data'Last), "&");

            Add_Parameter (K, Data (Index .. Amp - 1));

            Index := Amp + 1;

         end loop;

         --  add last parameter

         Add_Parameter (Count, Data (Index .. Data'Last));

      end Set_Parameter_Table;

   --  Start of processing for Initialize

   begin

      if Request_Method = "GET" then

         Initialize_GET;

      elsif Request_Method = "POST" then

         Initialize_POST;

      else

         Valid_Environment := False;

      end if;

   exception

      when others =>

         --  If we have an exception during initialization of this unit we

         --  just declare it invalid.

         Valid_Environment := False;

   end Initialize;

   ---------

   -- Key --

   ---------

   function Key (Position : Positive) return String is

   begin

      Check_Environment;

      if Position <= Key_Value_Table.Last then

         return Key_Value_Table.Table (Position).Key.all;

      else

         raise Parameter_Not_Found;

      end if;

   end Key;

   ----------------

   -- Key_Exists --

   ----------------

   function Key_Exists (Key : String) return Boolean is

   begin

      Check_Environment;

      for K in 1 .. Key_Value_Table.Last loop

         if Key_Value_Table.Table (K).Key.all = Key then

            return True;

         end if;

      end loop;

      return False;

   end Key_Exists;

   ------------------

   -- Metavariable --

   ------------------

   function Metavariable

     (Name     : Metavariable_Name;

      Required : Boolean := False) return String

   is

      function Get_Environment (Variable_Name : String) return String;

      --  Returns the environment variable content

      ---------------------

      -- Get_Environment --

      ---------------------

      function Get_Environment (Variable_Name : String) return String is

         Value  : OS_Lib.String_Access := OS_Lib.Getenv (Variable_Name);

         Result : constant String := Value.all;

      begin

         OS_Lib.Free (Value);

         return Result;

      end Get_Environment;

      Result : constant String :=

                 Get_Environment (Metavariable_Name'Image (Name));

   --  Start of processing for Metavariable

   begin

      Check_Environment;

      if Result = "" and then Required then

         raise Parameter_Not_Found;

      else

         return Result;

      end if;

   end Metavariable;

   -------------------------

   -- Metavariable_Exists --

   -------------------------

   function Metavariable_Exists (Name : Metavariable_Name) return Boolean is

   begin

      Check_Environment;

      if Metavariable (Name) = "" then

         return False;

      else

         return True;

      end if;

   end Metavariable_Exists;

   ------------

   -- Method --

   ------------

   function Method return Method_Type is

   begin

      Check_Environment;

      return Current_Method;

   end Method;

   --------

   -- Ok --

   --------

   function Ok return Boolean is

   begin

      return Valid_Environment;

   end Ok;

   ----------------

   -- Put_Header --

   ----------------

   procedure Put_Header

     (Header : String  := Default_Header;

      Force  : Boolean := False)

   is

   begin

      if Header_Sent = False or else Force then

         Check_Environment;

         Text_IO.Put_Line (Header);

         Text_IO.New_Line;

         Header_Sent := True;

      end if;

   end Put_Header;

   ---------

   -- URL --

   ---------

   function URL return String is

      function Exists_And_Not_80 (Server_Port : String) return String;

      --  Returns ':' & Server_Port if Server_Port is not "80" and the empty

      --  string otherwise (80 is the default sever port).

      -----------------------

      -- Exists_And_Not_80 --

      -----------------------

      function Exists_And_Not_80 (Server_Port : String) return String is

      begin

         if Server_Port = "80" then

            return "";

         else

            return ':' & Server_Port;

         end if;

      end Exists_And_Not_80;

   --  Start of processing for URL

   begin

      Check_Environment;

      return "http://"

        & Metavariable (Server_Name)

        & Exists_And_Not_80 (Metavariable (Server_Port))

        & Metavariable (Script_Name);

   end URL;

   -----------

   -- Value --

   -----------

   function Value

     (Key      : String;

      Required : Boolean := False)

      return     String

   is

   begin

      Check_Environment;

      for K in 1 .. Key_Value_Table.Last loop

         if Key_Value_Table.Table (K).Key.all = Key then

            return Key_Value_Table.Table (K).Value.all;

         end if;

      end loop;

      if Required then

         raise Parameter_Not_Found;

      else

         return "";

      end if;

   end Value;

   -----------

   -- Value --

   -----------

   function Value (Position : Positive) return String is

   begin

      Check_Environment;

      if Position <= Key_Value_Table.Last then

         return Key_Value_Table.Table (Position).Value.all;

      else

         raise Parameter_Not_Found;

      end if;

   end Value;

begin

   Initialize;

end GNAT.CGI;