Hi everyone,
I am studying socket programming. I have a problem about the function send(). Generally it is thought that the calls return the number of characters sent, or -1 if an error occurred. But when I practice programming about udp socket, the server return 0 when it actually sent data. I am really puzzled. Can anyone help me ? The program I practice is as follows.
------------------------------------------------------------------------------------
/*Authors: zxt
*problem left:
*in line 38:count=sendto(sd,"test from server",sizeof("test from server"),0,(struct sockaddr *) &s_addr,sizeof(s_addr))<0)
*when captured with etheral, it is found that the data has been sent,
*while the printed message shows that "0 byte send success!"
*/
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
int port = 5678;
int sendingcount=3;
char *dest_ip="100.0.0.9";
char bufftosend[40]="test from server";
int main(void)
{
int sd;
int i;
int count;
struct sockaddr_in s_addr;
sd=socket(AF_INET,SOCK_DGRAM,0);
printf("sd==%d\n",sd);
if(sd==-1)
{printf("socket created error!\n");
exit(0);
}
memset(&s_addr,0,sizeof(s_addr));
s_addr.sin_family=AF_INET;
s_addr.sin_addr.s_addr=inet_addr(dest_ip);
s_addr.sin_port=htons(port);
for(i=0;i<sendingcount;i++)
{
if(count=sendto(sd,bufftosend,sizeof(bufftosend),0,(struct sockaddr *) &s_addr,sizeof(s_addr))<0)
{
printf("send error!\n");
exit(0);
}
printf("%d byte send success!\n",count);
sleep(3);
}
}
-
: send the line "unsubscribe linux-c-programming" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
