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UDP server recvfrom() always returns -1? :(

UDP server recvfrom() always returns -1? :(

UDP server recvfrom() always returns -1? :(

(OP)
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 timeout\n");
       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?

RE: UDP server recvfrom() always returns -1? :(

You have a recv timeout set. Try removing that and see what happens.  The error you are getting i.e. EAGAIN may just imply that you have timed out.

 

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