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

Anti Spam Code
Ok where do i start? Probably by telling you I have very little working knowledge of PHP and that I

Line break?
Hi, I'm new to the forum and new to php. I'm not sure if I'm using the correct terminology so here i

DirectoryIterator and Hacked Website
Hi Everyone.

My problem:
Some one has been sneaking in to my website hidden Iframes. I've

Quick variable question
hey guys/gals,
im trying to write a php script and it works fine as i have it, but i need to set

standard ALV application toolbar, into custom report....
HI,

I have a question regarding displaying standard ALV menu path and application toolbar

writing a screen scraper
Hello,

I'm writing a screen scraper application and want to be able to get absolute addresses

frames get header location..
i have two frames, one top, one bottom. how do i do a form on the bottom frame that gives me the ur

no idea what to do...
I'm fed up. I had issues with code that I have working on a different site that didn't work on my cu

Select question
Hi,

First I would like to say that php is pretty new for me..
so please don't shoot me if

login page does not execute a else statement
I've created a login page using sessions.
When an incorrect user name or password is entered then

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