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From: "snoopysalive@googlemail.com" <snoopysalive@googlemail.com>
Newsgroups: comp.lang.ada
Subject: Re: How to implement a server socket compatible to telnet?
Date: Wed, 20 Aug 2008 14:25:04 -0700 (PDT)
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Date: 2008-08-20T14:25:04-07:00
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Come on guys, stop arguing. In the end, I've found a solution:

-----------------------------------------------------------------------
with Ada.Text_IO,
     Ada.Exceptions,
	 Ada.Streams,
	 Ada.Unchecked_Deallocation,
     GNAT.Sockets;
use Ada.Text_IO,
    Ada.Exceptions,
    Ada.Streams,
    GNAT.Sockets;

procedure IP_Server is

	BUFFER_SIZE : constant Positive := 1024;

	type String_Access is access all String;

	procedure Free is new Ada.Unchecked_Deallocation
		(String, String_Access);

	CRLF : constant String := ASCII.CR & ASCII.LF;
	Host : constant String := "localhost";
	Port : Port_Type       := 7777;

	Address : Sock_Addr_Type;
	Server  : Socket_Type;
	Client  : Socket_Type;
	Channel : Stream_Access;

	Data   : Stream_Element_Array (1..1);
	Offset : Stream_Element_Count;

	Buffer : String_Access := new String (1..BUFFER_SIZE);
	Cnt    : Natural := 0;

	Test : Float := 0.0;

begin -- IP_Server
	Initialize;

	Address.Addr := Addresses (Get_Host_By_Name (Host), 1);
	Address.Port := Port;

	Create_Socket (Server);
	Set_Socket_Option (Server, Socket_Level, (Reuse_Address, True));
	Bind_Socket (Server, Address);
	Listen_Socket (Server);
	Accept_Socket (Server, Client, Address);
	Channel := Stream (Client);

	Cnt := 0;
	loop
		Read (Channel.all, Data (1..1), Offset);
		if Character'Val (Data (1)) = ASCII.CR  or
		   Character'Val (Data (1)) = ASCII.LF  or
		   Character'Val (Data (1)) = ASCII.NUL or
		   Offset = 0 then
			exit;
		else
			Cnt := Cnt + 1;
			Buffer.all (Cnt) := Character'Val (Data (1));
		end if;
	end loop;
	-- Read values from client-stream character by character.
	-- Reading should be stopped when Windows-linefeed or
	-- NULL was found, because telnet seams to be sending
	-- strings in a Windows-like format including the
	-- terminating \0-character known from C-strings.

	declare
		Old : String_Access := Buffer;
	begin
		Buffer := new String'(Buffer (1..Cnt));
		Free (Old);
	end;
	-- The buffer-size of Str is 1024 elements. It's necessary
	-- to create a new String containing only relevant characters
	-- for being able to process the message further.

	declare
		Pong : String := "pong" & CRLF;
		O    : Stream_Element_Array (1..Pong'length);
	begin
		if Buffer.all = "ping" then
			for I in Pong'range loop
				O (Stream_Element_Offset (I)) := Character'Pos (Pong (I));
			end loop;
			Write (Channel.all, O);
		end if;
	end;
	-- If Buffer's message equals "ping" the server will
	-- send "pong" to the client. "pong" must be casted
	-- from String to Stream_Element_Array first.

	Close_Socket (Client);
	Close_Socket (Server);

	Finalize;

exception when E : Socket_Error =>
	Put_Line (Standard_Error, "Socket_Error => " & Exception_Message
(E));

end IP_Server;
-----------------------------------------------------------------------------------

Thanks to the thread under http://groups.google.com/group/comp.lang.ada/browse_thread/thread/c58b7bd180ea81b2
I found out how to read character by character from the client.
However, it's not very comfortable to cast the echo-string manually
but it's better than not being able to communicate with telnet or
other C-based clients.

Bye,
Matthias