Binding 2 UDP sockets on same port, connected to different destinations, 1 receives

Posted on 16th Feb 2014 07:03 pm by admin

Hello,
My application wants to send/recv data to 2 different UDP ports on a remote computer, using the same source port.
So I bind to the same local port which works, and connect to the remote IP : port which works as well, but then randomly only one of the two sockets will receive data from the stack, even though packets are arriving on the network for both.

In this code, the local UDP port is always 13398; the first time this code is called, the destination is 192.168.13.45:6970 and the second time it's 192.168.13.45:6972.
What would cause only one of the sockets to receive data afterwards? Also it's randomly the first or the second one that receive data, but once both sockets are binded and connected, only that random one will receive data.

Thanks!

SOCKET serverSock = ::socket(AF_INET, SOCK_DGRAM,IPPROTO_UDP);
int i=1;
if ( setsockopt(serverSock, SOL_SOCKET, SO_REUSEADDR, (char *)&i, sizeof(i)) != 0 ) {
logger.warn(_T("Could not set SO_REUSEADDR: %s"), GetWSATextError(WSAGetLastError()));
}

SOCKADDR_IN saServer, dest;
memset(&saServer,0,sizeof(saServer));
saServer.sin_family = AF_INET;
saServer.sin_addr.s_addr = INADDR_ANY; // Since this is a server, any address will do
saServer.sin_port = htons(m_manager->GetLocalUDPPort()); // Convert int to a value for the port field
int ret = bind(serverSock, (struct sockaddr *) &saServer, sizeof(saServer));
if (ret != 0) {
logger.warn(_T("Could not bind to udp port 1: %d, %s"), m_manager->GetLocalUDPPort(), GetWSATextError(WSAGetLastError()));
return false;
}

memset(&dest,0,sizeof(dest));
dest.sin_family=AF_INET;
dest.sin_addr.s_addr=m_deviceIP;
dest.sin_port = htons(m_devicePort1);
ret = connect(serverSock, (sockaddr *) &dest, sizeof(dest));
if (ret != 0) {
logger.warn(_T("Failed to connect to udp 1: %s:%d, %s"), inet_ntoa(dest.sin_addr), m_devicePort1, GetWSATextError(WSAGetLastError()));
return false;
}

Your Answer:

Login to answer

Other forums

Points for Wiki contribution
Hi everyone,

I want to know how long does it take for the moderator to award points for a

database design
Hi,

I got a page which allow candidate to type in their previous working experience,
I let

help with variable
I've got a problem, i want to echo some images depending on the $id, however for me to get that id i

Most basic form question ever?
Hello,

I want to use this snippet to make sure the fields in a form are ok before processing

Using Microsoft Exchange Server with PHP
Hi,

I wanted to know if its possible to fetch email attachments from the exchange server usin

restricting another login once you logout
Hello,

how can I restrict a page from login authenticating against info in a MySQL DB for a s

Php mysql - select?
Hi i have this code:
Code: $iteminfo = mysql_query("SELECT desc FROM wc_items WHERE itemid =

mysql_query returning boolean instead of mysql ressource
Hi,

I seem to have a weird issue with the php command mysql_query. I pass 2 arguments the que

Running a cron job through PHP/Apache?!
Hello all,
I have a PHP script which makes a cron file from user input. When i try to run the cro

Multi image upload
I have a gallery to build and want to build a dynamic upload form to allow for $var number of fields