Re: Help with UDP data handler

Thanks that's a good idea. I may deploy this approach in my application. 
Could you tell me how you are getting the remote IP and PORT for the 
recvfrom call?

Thanks.

On 07/31/2012 12:29 PM, Steve Trigero wrote:
> I can't tell you what you might doing wrong, but I can offer
> some suggestions based on how I did something similar.
> I did not use the callback feature. It seems to me there are
> too many messages flying around to use this feature reliably.
> I open several UDP sockets listening for broadcast messages.
> for(i=0;i<UDP_SOCKETS;i++){
> udp_extopen(&udpcon[i].socket,
> IF_DEFAULT,
> UDP_BROADCAST_PORT,
> -1,-1,NULL,0,0);
> }
> In the main loop I call a function that checks each socket for
> a received message. If a message with data is found, the data
> is copied to a buffer and passed to a paring routine.
>    // Look for incoming packets.
>    for  (s=0;  s<UDP_SOCKETS;  s++  ){
>
>      if  (!udp_peek(&udpcon[s].socket,NULL  ) ){
>        continue;  // No packets...
>      }
>
>      numBytes  =  udp_recvfrom(&udpcon[s].socket,
>                                udpcon[s].buf,
>                                sizeof(udpcon[s].buf),
>                                &udpcon[s].ip,
>                                &udpcon[s].port  );
>      if  (numBytes  <  1  ){
>        continue;  // No data...
>      }
>      udpcon[s].buf[numBytes]  =  NUL;
>      UdpParse(&udpcon[s]  );
> }
> Occasionally, my program sends its own broadcast status.
> When it does, it opens a UDP port, sends the message, then
> closes the port.
>    // Open a Broadcast socket
>    if  (!udp_extopen(&udpsock.socket,IF_DEFAULT,UDP_BROADCAST_PORT-1,
>                        -1,UDP_BROADCAST_PORT,NULL,0,0  ) )
>      return;  // Oops!
>
>    // Build a status message
>    FormatUDPStatusMsg(udpsock.buf  );
>
>    // Send it...
>    udp_send(&udpsock.socket,udpsock.buf,strlen(udpsock.buf) );
>    udp_close(&udpsock.socket  );
> This works well in our system.
>
>     *From:* Jeff Powell <jrpinjapan-/[email protected]>
>     *To:* [email protected]
>     *Sent:* Monday, July 30, 2012 8:57 AM
>     *Subject:* [rabbit-semi] Help with UDP data handler
>
>     I posted this as part of a different question and nobody answered
>     so I
>     will try again as it's own topic.
>
>     I have opened a udp socket with a datahandler.
>     I opened a second udp socket for sending multicast data when
>     values change.
>     I get a connection, read from client, write back to client.
>     I get another connection. It does not go to the datahandler.
>     The main loop runs and multicast data continues to send properly.
>
>     What am I missing?
>
>     -- code --
>     if (!udp_open(&tsock, LOCAL_PORT, 0, 0, dataHandler))
>     {
>     printf("udp_lst_open failed!\n");
>     exit(0);
>     }
>     else
>     {
>     printf("Listener %s:%d\n",MY_IP_ADDRESS,LOCAL_PORT);
>     }
>     if (!udp_open(&usock, MBUS_PORT, resolve(MBUS_ADDRESS), MBUS_PORT,
>     NULL))
>     {
>     printf("udp_open failed!\n");
>     exit(0);
>     }
>
>     ...
>
>     while (1)
>     {
>     idleProcessing(); // where values are processed and
>     multicast data is sent as needed.
>     tcp_tick(NULL);
>     }
>
>     ...
>
>     int dataHandler(int event, udp_Socket *s, ll_Gather *g,
>     _udp_datagram_info *udi)
>     {
>     int status;
>     char cip[20];
>     CARDMSG_S *pkt;
>     if(handleUdp) // stops recursion, does not effect
>     handler death
>     return 1;
>     handleUdp=1;
>     if(event == UDP_DH_ICMPMSG) // from the example
>     {
>     return 1;
>     }
>     memset(&replyMsg, 0, sizeof (REPLYMSG_S));
>     xmem2root(pktbuf, g->data2, g->len2);
>     if(g->len3>0)
>     xmem2root(pktbuf+g->len2, g->data3, g->len3);
>     pkt=(CARDMSG_S*) &pktbuf;
>     inet_ntoa( cip, udi->remip);
>     printf("%s:%u Slot %d Type %d Device %d Offset %x Width %x Data %lx
>     %lx\n", cip, udi->remport, pkt->cSlot, pkt->cOperation, pkt->cDevice,
>     pkt->cOffset, pkt->cDataWidth, pkt->sData.longs[1],
>     pkt->sData.longs[0] );
>     status = process_packet(pktbuf);
>     replyMsg.eStatus = status;
>     printf("Status: %x\n", status);
>     udp_sendto(s, (char*) &replyMsg, sizeof(REPLYMSG_S), udi->remip,
>     udi->remport); // straight from the
>     // even tried this but it does not help either. Returns 1 for NULL or
>     bytes recv'd for the incoming socket.
>     printf("Sent response %u\n", tcp_tick(NULL));
>     handleUdp=0;
>     return 1;
>     }
>
>
>
>