Re: [lwip-users] UDP bind error due to address and port reuse

[Surya Chaitanya]

Hi Dirk,

udp_sendto() function stops sending after sending few times, i.e., the packets 
are 
not reaching the destination. What could be the problem? Thank You.

Regards,
Surya


On Tue, 13 Dec 2016 12:49:25 +0100, Dirk Ziegelmeier wrote
> The arguments to the function are the *source* IP/Port tuple of the request.
> 
> If you use udp_sendto() then the the *reply *packet has
> 
>    - Source IP: IP of your lwIP device
>    - Source port: Port in your lwIP device ("x")
>    - Destination IP: source IP of the request = addr parameter of function
>    - Destination port: source port of the request = port parameter of the
>    function
> 
> Dirk
> 
> On Tue, Dec 13, 2016 at 6:58 AM, Surya Chaitanya <address@hidden> wrote:
> 
> > Hi Dirk,
> >
> > I tried out the few lines of code like you suggested. It works. However,
> > what I
> > don't understand is how it works, i.e., how the port parameter in the
> > function is
> > the port sending the reply. Could you plz. explain. Thank You.
> >
> > Regards,
> > Surya
> >
> > On Wed, 7 Dec 2016 11:43:59 +0100, Dirk Ziegelmeier wrote
> > > Use one UDP PCB, bind it to IPADDR_ANY and port x.
> > >
> > > Use udp_sendto() to send to any IP/port combination.
> > > http://www.nongnu.org/lwip/2_0_0/group__udp__raw.html
> > >
> > > You get the src address/port of any request in your receive callback:
> > >
> > > void my_udp_recv_fn (void *arg, struct udp_pcb
> > > <http://www.nongnu.org/lwip/2_0_0/structudp__pcb.html> *pcb, struct pbuf
> > > <http://www.nongnu.org/lwip/2_0_0/structpbuf.html> *p, const ip_addr_t
> > >
> > <http://www.nongnu.org/lwip/2_0_0/group__ipaddr.html#
> > ga44f9ada14c65d17aecf802d82eb27
> > 3c5>
> > > *addr, u16_t port)
> > > {
> > >    [create new pbuf with response]
> > >    udp_sendto(pcb, response_pbuf, addr, port);
> > > [UTF-8?][UTF-8?]​}
> > >
> > > [UTF-8?][UTF-8?]​Dirk
> > > [UTF-8?][UTF-8?]​
> >
> >
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