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

Async WSAConnect failed on XP with error code = 2 ("File not found")
Hi all,

I have very strange bug, please help me if you can.

It is reproduced o

Mouseover to edit (Ajax)
hi friends, can anyone help with the code behind to get this application working, please in VB (new

DateObject and Nulls
Hi all,

I have an array mapped to a value object. One of the items in the array is a PHP Date

breaking a text file into paragraphs based on strings
I have a text file of email addresses that is all squished together. It looks like this:

abc

Comparing Values
Hi
I'm reading data from a database and this seems to work OK.

Each system has an associat

PHP, jAVASCRIPT setting input values, why isn't it working?
Hi:

I am calling this javascript:
<script language="javascript">

Using system() and bringing back the results
I am aware that you can use system() within PHP to execute system commands, but I was wondering if t

convert static html data into dynamic
hi all

i need to convert a website which has static above 2000 articles into dynamic and add

GMail like Chat in ASP.NET
Hi,Can anyone suggest me, how to incorporate GMail like chat in my existing ASP.Net application.I wa

MSSQL/PHP
I am tryint to setup a webapplication developed in PHP, Apache2.0 and SQLServer2000 as backend which