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?

No comments posted yet

Your Answer:

Login to answer
125 Like 16 Dislike
Previous forums Next forums
Other forums

Send inserts to mysql thru port 80
Hi!

I have an application that must do some inserts in a mysql db. This db is behind a firewa

image upload script not working with png
The basic process of this php code is to take the submitted file, convert it to a small JPG thumbnai

add to sql result
ok see rite now my sites hit counter is counted from the mysql visitor log i need to clear it aft

Weird problem with SELECT command..Help!
Hi!

It seems I'm having a really weird problem with SQL SELECT command....I have table into a

Sessions Value Not Saved
Hi,

Im making a login form and im using this code:
Code: if($login=="true"){

Multiple arrays inside data
Hi,

Simple question. I have a column called "array" in my database, and inserted in

Help with parsing this html
Hi,
I've got some html i just need a couple of strings from.. argh, it's freaking me out. I've t

Calling strings from other php class
I have test1.php{
$string1;
$string2;
....
... //10 strings in this class <

If a record matches an existing record do nothing
So I don't know if I should put this here or in mysql, but what my script is for is for people to ad

Stopping page post back
I have few literal contriols in my page and a repeater too. But inspite of using update panel, postb

Sign up to write
Sign up now if you have flare of writing..
Login   |   Register
Follow Us
Indyaspeak @ Facebook Indyaspeak @ Twitter Indyaspeak @ Pinterest RSS



Play Free Quiz and Win Cash