RE: [lwip-users] Has any work been done on allowing sendandreceive on a single port

[Taranowski, Thomas (SWCOE)]

> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden
On
> Behalf Of Kieran Mansley
> Sent: Monday, January 21, 2008 3:24 AM
> To: Mailing list for lwIP users
> Subject: RE: [lwip-users] Has any work been done on allowing
> sendandreceive on a single port
> 
> On Mon, 2008-01-21 at 11:11 +0000, Julian Gardner [RSD] wrote:
> > Ive done
> >
> >     sock = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP);
> >
> >     memset( ( void * )&sockAddr, 0, sizeof( struct sockaddr_in ) );
> >     sockAddr.sin_family = AF_INET;
> >     sockAddr.sin_addr.s_addr = INADDR_ANY;
> >     sockAddr.sin_port = port;
> >     if( bind( sock, ( struct sockaddr * )&sockAddr, sizeof( sockAddr
) )
> > !=0)
> >     {
> >     }
> >
> > Now do i need to do anything else to make this bi-directional?.
> 
> I'm still not clear what you're trying to achieve.
> 
> All sockets are by default one-to-one and bi-directional.
> 
> If you just need to do bi-directional communication between two
> computers (A sends to B, B sends back to A), you should get that with
no
> trouble at all with a normal socket.
> 
> If you want three computers (i.e. A sends to B, and B sends to C) then
B
> will need two sockets.  It can't use one socket for both receiving
from
> A and sending to C as sockets are normally just one-to-one.  Both
those
> sockets can be on the same address and port at B (I think) though.
You
> may have to be a bit careful about how you bind them to ensure they
> don't "overlap".

[TT] I had problems when a customer bound 2 UDP sockets to the same
local port and address.  Leon had put in some code to handle it, but it
was #ifdef'd out, and would cause the tcpip thread to lock up for me.
It's been a couple weeks, but apparently the bsd-way to handle this is
to allow two sockets to bind to the same port so long as the local
address is different.  I was going to work on it, but am busy elsewhere,
so use caution when binding to the same port.



> 
> You may, if that doesn't fulfill your needs, be able to do something
> with multicast (as then the socket isn't just one-to-one) but that's a
> whole different kettle of fish.
> 
> Kieran
> 
> 


> 
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