Udp server sending only 0 bytes of data

Question

Hi all, This is a simple Udp server.I am trying to transmit data to some clients,but unfortunetly it is unable to transmit data.Though send is running quite successfully but it is returning with a return value meaning it has send nothing.On the client they are receiving but again obviously,zero bytes.

   void* UdpServerStreamToClients(void *fileToServe)
   {

    int sockfd,n=0,k;
struct sockaddr_in servaddr,cliaddr;
socklen_t len;
char dataToSend[1000];

sockfd=socket(AF_INET,SOCK_DGRAM,0);

bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
servaddr.sin_port=htons(32000);
bind(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr));


FILE *fp;
if((fp=fopen((char*)fileToServe,"r"))==NULL)
    {
        printf("can not open file ");
        perror("fopen");
        exit(1);
    }


int dataRead=1;
while(dataRead)
{

    len = sizeof(cliaddr);
    if((dataRead=fread(dataToSend,1,500,fp))<0)
    {
        perror("fread");
        exit(1);
    }

    //sleep(2);




    for(list<clientInfo>::iterator it=clients.begin();it!=clients.end();it++)
    {
        cliaddr.sin_family = AF_INET;
        inet_aton(inet_ntoa(it->addr.sin_addr),&cliaddr.sin_addr);
        cliaddr.sin_port = htons(it->udp_port);
        n=sendto(sockfd,dataToSend,sizeof(dataToSend),0,(struct sockaddr *)&cliaddr,len);
        cout<<"number of bytes send by udp: "<< n << endl;  
            printf("SEND this message %d : %s to %s :%d \n",n,dataToSend,inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port));
    }           



}

}

I am checking the value of sizeof(dataTosend) and it is pretty much as expected ie thousand ie the size of buffer. Are you people seeing some possible flaw in it. All of the help in this regard will be appreciated. Thanks!

Answer 1

Not sure this is the exact answer, but you forgot to memset() (or bzero()) the cliaddr structure before using it.

Also, the line:

inet_aton(inet_ntoa(it->addr.sin_addr),&cliaddr.sin_addr);

Could probably be written:

cliaddr.sin_addr = it->addr.sin_addr;