Re: Help with UDP data handler

The function udp_recvfrom() stuffs the ip and port values from the received datagram
into the ip and port function arguments. That way, if the message requires a response
I can respond to the specific ip and port of the host device.
 
steve

From: Jeff Powell <jrpinjapan-/[email protected]>
>To: [email protected] 
>Sent: Tuesday, July 31, 2012 2:01 PM
>Subject: Re: [rabbit-semi] 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 mailto: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;
>>>}
>>>
>>>
>>>
>>>
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