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

Php mysql - select?
Hi i have this code:
Code: $iteminfo = mysql_query("SELECT desc FROM wc_items WHERE itemid =

reating a background image
I am building a site in drupal and have a php form in it, due to certain annoyances with module buil

what business processes?
Hi,

A general question. What business processes (like OTC - Order to Cach, P2P, R2R etc)

* Gridview and Detailsview in UpdatePanel, insert mode problem
I have a GridView and DetailsView working together. When a record from Gridview is selected, Detail

Help with PHP Calendar code...
Hello, I'm new to this forum and I'm glad I found it.
I wrote this code for a PHP calendar as an

i need help with php header and footer
I have designed a header and footer for my site and they seem to be ok when they are running individ

Windows Authentication
I have a website which is windows authenticated.
now i want something more on this application.<

help me, how to find text on an external html site using PHP
Would anyone know how to search an external html file for a work or phrase ?

I was thinking s

Any decent php formatter/beautifier/pretty printer?
Any decent php formatter/beautifier/pretty printer class/function?

I found the following whil

RFQ Configuration - can you make PLANT field an optional field in ME42
Is there a way to make the plant field on an RFQ optional in change mode (ME42)?