TCP Server & Client

TCP Server & Client

[Andrew Shvets]

Hello, I'm trying to write a small client/server example:

This is the client:
==============================================================================
with Ada.Streams;
with Ada.Text_IO;

with GNAT.Sockets;

procedure TCP_Client is
  Address : GNAT.Sockets.Sock_Addr_Type;
  Socket : GNAT.Sockets.Socket_Type;
  Data : constant Ada.Streams.Stream_Element_Array(1 .. 512) := (others => 42);
  Last : Ada.Streams.Stream_Element_Offset;
begin
  GNAT.Sockets.Initialize;

  Address.Port := 50001;
  Address.Addr := GNAT.Sockets.Inet_Addr("127.0.0.1");
  Ada.Text_IO.Put_Line("Hello 1");
  GNAT.Sockets.Create_Socket(Socket, GNAT.Sockets.Family_Inet, GNAT.Sockets.Socket_Stream);
  Ada.Text_IO.Put_Line("Hello 2");
  GNAT.Sockets.Set_Socket_Option(Socket, GNAT.Sockets.Socket_Level, (GNAT.Sockets.Reuse_Address, True));
  Ada.Text_IO.Put_Line("Hello 3");
  GNAT.Sockets.Send_Socket(Socket, Data, Last, Address);
  Ada.Text_IO.Put_Line("last :" & Last'Img);

  GNAT.Sockets.Finalize;
end TCP_Client;
==============================================================================

This is the server:
==============================================================================
with Ada.Streams;
with Ada.Text_IO;

with GNAT.Sockets;

procedure TCP_Server is
  Server : GNAT.Sockets.Socket_Type;
  Sock   : GNAT.Sockets.Socket_Type;
  Address : GNAT.Sockets.Sock_Addr_Type;
  From : GNAT.Sockets.Sock_Addr_Type;
  Data : Ada.Streams.Stream_Element_Array(1 .. 512);
  Last : Ada.Streams.Stream_Element_Offset;
  Watchdog : Natural := 0;
begin
  GNAT.Sockets.Initialize;

  GNAT.Sockets.Create_Socket(Server, GNAT.Sockets.Family_Inet, GNAT.Sockets.Socket_Stream);
  GNAT.Sockets.Set_Socket_Option(Server, GNAT.Sockets.Socket_Level, (GNAT.Sockets.Reuse_Address, True));
  Address.Addr := GNAT.Sockets.Any_Inet_Addr;
  Address.Port := 50001;
  GNAT.Sockets.Bind_Socket(Server, Address);

  loop
    begin
      GNAT.Sockets.Listen_Socket(Server);
      GNAT.Sockets.Accept_Socket(Server, Sock, Address); 
      GNAT.Sockets.Receive_Socket(Server, Data, Last, From);
      Ada.Text_IO.Put_Line("last : " & Last'Img);
      Ada.Text_IO.Put_Line("from : " & GNAT.Sockets.Image(From.Addr));
    exception
      when GNAT.Sockets.Socket_Error =>
        Ada.Text_IO.Put_Line("ERROR: Socket error caught.");
    end;
  end loop;
end TCP_Server;
==============================================================================


When I run the client, this is what I see:
Hello 1
Hello 2
Hello 3

raised GNAT.SOCKETS.SOCKET_ERROR : [32] Broken pipe




Why is this happening?  If possible, I'd like to use the Send_Socket method in the client.  Thanks.

Re: TCP Server & Client

[Simon Wright]

Andrew Shvets <andrew.shvets@gmail.com> writes:

> procedure TCP_Client is
[...]
>   GNAT.Sockets.Create_Socket(Socket, GNAT.Sockets.Family_Inet, GNAT.Sockets.Socket_Stream);

>   GNAT.Sockets.Set_Socket_Option(Socket, GNAT.Sockets.Socket_Level, (GNAT.Sockets.Reuse_Address, True));

>   GNAT.Sockets.Send_Socket(Socket, Data, Last, Address);

If you look at the spec of GNAT.Sockets for a long time you will see
that there are 3 versions of Send_Socket, only 2 of which I would expect
to use, and you've chosen the wrong one (the last, datagram,
version). You need the second:

   procedure Send_Socket
     (Socket : Socket_Type;
      Item   : Ada.Streams.Stream_Element_Array;
      Last   : out Ada.Streams.Stream_Element_Offset;
      Flags  : Request_Flag_Type := No_Request_Flag);

More importantly, you've left out the Connect_Socket call (which is what
the server Accept_Socket call is waiting for).

Check out the commentary at the beginning of g-socket.ads, look for
'task body ping'.


Also, in TCP_Server, you should be calling Receive_Socket on Sock (the
new socket which is actually connected to TCP_Client).

Re: TCP Server & Client

[Andrew Shvets]

On Sunday, March 25, 2018 at 4:22:32 AM UTC-4, Simon Wright wrote:
> Andrew Shvets <an....@gmail.com> writes:
> 
> > procedure TCP_Client is
> [...]
> >   GNAT.Sockets.Create_Socket(Socket, GNAT.Sockets.Family_Inet, GNAT.Sockets.Socket_Stream);
> 
> >   GNAT.Sockets.Set_Socket_Option(Socket, GNAT.Sockets.Socket_Level, (GNAT.Sockets.Reuse_Address, True));
> 
> >   GNAT.Sockets.Send_Socket(Socket, Data, Last, Address);
> 
> If you look at the spec of GNAT.Sockets for a long time you will see
> that there are 3 versions of Send_Socket, only 2 of which I would expect
> to use, and you've chosen the wrong one (the last, datagram,
> version). You need the second:
> 
>    procedure Send_Socket
>      (Socket : Socket_Type;
>       Item   : Ada.Streams.Stream_Element_Array;
>       Last   : out Ada.Streams.Stream_Element_Offset;
>       Flags  : Request_Flag_Type := No_Request_Flag);
> 
> More importantly, you've left out the Connect_Socket call (which is what
> the server Accept_Socket call is waiting for).
> 
> Check out the commentary at the beginning of g-socket.ads, look for
> 'task body ping'.
> 
> 
> Also, in TCP_Server, you should be calling Receive_Socket on Sock (the
> new socket which is actually connected to TCP_Client).

Thank you Simon.  That did the trick.