Tcl Source Code

port number will be chosen at random by the system software.
.TP
\fB\-async\fR
.
This option will cause the client socket to be connected
asynchronously. This means that the socket will be created immediately
but may not yet be connected to the server, when the call to
\fBsocket\fR returns.

When a \fBgets\fR or \fBflush\fR is done on the socket before the
connection attempt succeeds or fails, if the socket is in blocking
mode, the operation will wait until the connection is completed or
fails. If the socket is in nonblocking mode and a \fBgets\fR or
\fBflush\fR is done on the socket before the connection attempt
succeeds or fails, the operation returns immediately and
\fBfblocked\fR on the socket returns 1. Synchronous client sockets may
be switched (after they have connected) to operating in asynchronous
mode using:
.RS
.PP
.CS
\fBchan configure \fIchan \fB\-blocking 0\fR
.CE
.PP
See the \fBchan\fR \fBconfigure\fR command for more details.

The Tcl event loop should be running while an asynchronous connection
is in progress, because it may have to do several connection attempts
in the background. Runnig the event loop also allows you to set up a
writable channel event on the socket to get notified when the
asyncronous connection has succeeded or failed. See the \fBvwait\fR
and the \fBchan\fR comands for more details on the event loop and
channel events.

.RE
.SH "SERVER SOCKETS"
.PP
If the \fB\-server\fR option is specified then the new socket will be
a server that listens on the given \fIport\fR (either an integer or a
service name, where supported and understood by the host operating
system; if \fIport\fR is zero, the operating system will allocate a

test socket-14.2 {[socket -async] fileevent connection refused} \
    -constraints [list socket supported_any] \
    -body {
        set client [socket -async localhost [randport]]
        fileevent $client writable {set x [fconfigure $client -error]}
        set after [after 1000 {set x timeout}]
        vwait x
        if {$x eq "timeout"} {
            append x ": [fconfigure $client -error]"
        }
        set x
    } -cleanup {
        after cancel $after
        close $client
        unset x
    } -result "connection refused"

	     * will set up a file handler on the socket if she is interested
	     * in being informed when the connect completes.
	     */
	    
	    status = connect(state->fds.fd, state->addr->ai_addr,
                             state->addr->ai_addrlen);
	    if (status < 0 && errno == EINPROGRESS) {
                Tcl_CreateFileHandler(state->fds.fd,
                                      TCL_WRITABLE | TCL_EXCEPTION,
                                      TcpAsyncCallback, state);
                return TCL_OK;

            coro_continue:
                Tcl_DeleteFileHandler(state->fds.fd);
                /*
                 * Read the error state from the socket, to see if the async