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

Looking for help on using joining mysql tables and php....
Does anyone have any good links to references on how to pull mysql data, through joining tables and

MySQL noob question
hi guys

I have a simple mysql table set up, along the lines of

Col 1 - Col 2 - Date_l

parse error
On my local machine I keep getting parse error for my footer. When I put it online, it doesn't show

Confused with Loop
guys, i got confused with Looping...this is the case

I have 3 stocks, let say "Stock A&q

Displaying data from database into a 2 dimensional table
Good day!

I'm a beginner in PHP and I'm not expecting a full coding for this qestion. I'm jus

Fetching META TAGS through
Hello everybody
I want to fetch meta tags of a domain.
It will be done from following code of

Multiple websites question.
Hi, does php have any functionality that enables a programmer to extract information from a website

Problem with array max size.
Hi to everyone,
I've got a homework about filling a bidimensional array un spiral shape, I alre

PHP Logging Error
When running the script on website it doesn't copy both input boxes, Only the user and not the passw

php mail form text wont appear / javascript included
Guys/gals...

I am running into a problem whereby I have a great piece of javascript code that