Am Samstag, 9. Mai 2009 20:25 schrieb dmitry boyarintsev:
> > How can I find out if a socket connection in a nonblocking mode is
> > established?
>
> according to the man page, you're doing correct path:
> http://linux.die.net/man/2/connect
> i did use non-blocking connection for both Linux and OSX, and it did
> work as described: by "selecting" sockets for writting. Thought i used
> infinite wait time.
>
> Anyway, could you provide more code, on how do you actually establish
> a server address (sockaddr structure). I remeber there were some
> differences in Windows sockaddr structure and Linux sockaddr structure
> (IIRC, IP byte order is messed-up).
With nonblocking sockets it works.
Also it works with linux if I call connect again and again (nonblocking) until
the result from connect says ok, connected.
But I don't know exactly if there is more traffic on the network or internet
lines when calling connect often.
Windows may produces traffic every time by calling connect I think. But I am
not sure. This was the reason why I tried with select to find out if a
connection is ok.
I tested with longer timeouts, but for me there is the same behaviour.
Another way to find out can be to program select in c, put it in a library and
then call it from fpc.
regards, Rainer
var
c_connected : boolean;
c_socket : integer;
inetaddr_client_remote : tsockaddr;
implementation
const port_program = 12021;
procedure memclr( p : pointer ; len : longint );
var x : longint;
begin
for x := 1 to len do begin
byte( p^ ) := 0;
inc( p );
end;
end;
procedure setsockaddr( var sa : tsockaddr ; adr : string ; port : longint );
begin
memclr( @sa , sizeof( sa ) );
sa.sin_family := AF_INET;
sa.sin_addr := strtonetaddr( adr );
sa.sin_port := htons( port );
end;
function my_connect( s : integer ; var ina : tsockaddr ) : boolean;
var c : longint;
begin
c := fpconnect( s , @ina , sizeof( ina ) );
{$ifdef windows}
if c = SOCKET_ERROR then begin
if wsagetlasterror = WSAEISCONN then c := 0; // !
end;
{$endif}
result := ( c = 0 );
end;
procedure setnonblockingsocket( s : integer );
var
nb : dword;
n : integer;
arg : longint;
begin
// nonblocking
{$ifdef linux}
arg := fpfcntl( s , F_GETFL );
if arg >= 0 then begin
arg := arg or O_NONBLOCK;
fpfcntl( s , F_SETFL , arg );
end;
{$endif}
{$ifdef windows}
nb := 1; // 1 = nonblocking, 0 = blocking
n := winsock2.ioctlsocket( s , FIONBIO , @nb );
{$endif}
end;
function is_writable_socket( s : integer ; var error : longint ) : boolean;
var
fds : tfdset;
tv : timeval;
valopt : longint = 1;
vallen : {$ifdef linux} longword {$else} longint {$endif};
begin
result := false;
{$ifdef linux} fpfd_zero( fds ); fpfd_set( s , fds ); {$endif}
{$ifdef windows} fd_zero( fds ); fd_set( s , fds ); {$endif}
tv.tv_sec := 0;
tv.tv_usec := 0;
// socket+1 , read , write , except , timeout
{$ifdef linux}
if fpselect( s + 1 , nil , @fds , nil , @tv ) > 0 then begin
if fpfd_isset( s , fds ) = 1 then begin
vallen := sizeof( valopt );
if fpgetsockopt( s , sol_socket , so_error , @valopt , @vallen ) = 0
then begin
error := valopt;
result := valopt = 0;
end;
end;
end;
{$else}
if select( s + 1 , nil , @fds , nil , @tv ) > 0 then begin
if fd_isset( s , fds ) then begin
vallen := sizeof( valopt );
if getsockopt( s , sol_socket , so_error , valopt , vallen ) = 0 then
begin
error := valopt;
result := valopt = 0;
end;
end;
end;
{$endif}
end;
function ip_client_start_socket( s : string ) : boolean;
begin
result := false;
setsockaddr( inetaddr_client_remote , s , port_program );
c_socket := fpsocket( PF_INET , SOCK_STREAM , 0 );
if c_socket >= 0 then begin
setnonblockingsocket( c_socket ); // nonblocking connect call
result := my_connect( c_socket , inetaddr_client_remote );
end;
// setnonblockingsocket( c_socket ); // blocking connect call, if this is
executed later
c_connected := false;
end;
function ip_client_is_connected( var error : longint ) : boolean;
begin
if not( c_connected ) then c_connected := is_writable_socket( c_socket ,
error );
result := c_connected;
end;
procedure ip_client_close_socket;
begin
if c_socket >= 0 then closesocket( c_socket );
c_socket := -1;
c_connected := false;
end;
> thanks,
> dmitry
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