UDP server recvfrom() always returns -1? :(

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

Hello all,
I am getting a very strange error in my code :( I am writing a server application in C, to send and receive UDP packets to/from a client. Right now, im just running a loop in which the server receives packets using recvfrom() however.... the function seems to block and everytime I send it something, it sets errno to "resource temporarily unavailable" which is strange, cause it blocks until I send something, meaning that it knows something came no? However, recvfrom always returns -1 This is how I initialized the socket:

//struct timeval tv;

if((s = socket(AF_INET, SOCK_DGRAM, 0))==-1)
return 0;

bzero(&si_me,sizeof(si_me));
si_me.sin_family = AF_INET;
si_me.sin_port = htons(PORT);
si_me.sin_addr.s_addr = htonl(INADDR_ANY);

/*** Set socket timeout ***
tv.tv_sec = 1;
tv.tv_usec = 0;
if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0)
{
printf("Couldn't set socket timeoutn");
return 0;
}*/

if(bind(s,(struct sockaddr*) &si_me, sizeof(si_me))==-1)
return 0;

return 1;

and then I ran:
do
{
done = recvData();
printf("Received %d n", done);

}while(done == 0);

with recvData() being:

int recvData(void)
{
if (recvfrom(s, (char*)&buf, UDP_BUFFER_LEN, 0, (struct sockaddr*) &si_other_comp, &slen)==-1)
{
printf("Couldn't read socket (%s)n",strerror(errno));
return 0;
}

return 1;
}

so, program does nothing until it gets a packet, then says it cant read it and then continues doing nothing until it gets another packet.... any ideas?

Your Answer:

Login to answer

Other forums

help countdown timers
hello every one,

I'd like to know how to insert many countdowns in the same page.
The dura

Pagination
Okay here is the page in question: http://blenderteachings.000a.biz/tutorials.hamishhill.php

problem with GROUP BY and ORDER BY
i usually use this query to display the last 10 entries from a sql table:

Code: $query = &quo

Insert data in Mysql and move to another page
I'm stuck with this simple problem. I need to insert data in Mysql and then hit submit and move to a

CU&UC guide
Hi Gurus,

can anybody provide me the link for CU&UC upgrade guide

Thanks i

Problem with coding MySQL query
I'm having heaps of trouble getting one of my PHP/MySQL queries to work for some reason (and the fun

Multithreading design
Hi

I have come up with a Singleton class that manages a pool of database connections. Basical

PHP and SMS
Hi all forum members. I am new here and am unsure what category shoild I post this in.
Moderator

what are '%S%', '%E%'
for example when i see Code: [Select]printf("Hello %srn", $name);
what does %s means

Delete all from a table
I can not get the following code to work. If I run the sql statement in the db it will delete all t