I have a function that gets called each time I want to send a UDP packet.
Things work great if I take these steps:
- Create the socket
- Set the socket options
- Send the packet
- Close the socket
However, I don't want to incur the overhead of constantly creating the socket each time the function is called.
Is there a preferred way to handle this? I only want to create the socket once, then keep re-using it. I've tried doing this by introducing a "first_time" flag - but when I take this approach, the sendto() function starts failing with an errno 0x23.
Since I'm working in VxWorks - it's unclear to me whether this error code is ENOTSUP (VxWorks Error Code) or EWOULDBLOCK (sendto error code). Either way, I'm not what the fix is.
See my code below.
/* Global Scope */
int send_socket = 0;
int first_time = 1;
void myFunction(...)
{
if (first_time == 1)
{
first_time = 0;
send_socket = socket(PF_INET , SOCK_RAW , IPPROTO_UDP);
if(send_socket < 0)
perror("socket() error");
/* Inform the kernel do not fill up the packet structure. */
/* We will build our own... */
if(setsockopt(send_socket, IPPROTO_IP, IP_HDRINCL, val, sizeof(one)) < 0)
perror("setsockopt() error");
}
// ... populate buffer ...
if(sendto(send_socket,
*buffer,
my_ip_header->total_length,
0,
(struct sockaddr *)&sin,
sizeof(sin)) < 0)
{
perror("sendto error");
}
// Normally I'd close the socket right here...
// But I don't want to do this, because I want to use it later!
// close(send_socket);
}
