On Sunday, 24 May 2015 at 16:51:44 UTC, CodeSun wrote:
Hello guys,
Today, I found a weird problem when I was learning to enable
SO_KEEPALIVE for a specific socket. I use setsockopt to enable
keepalive firstly, and then use getsockopt to show if it is
enabled correctly.
My code snippet is listed below:
Dlang version:
import core.sys.posix.sys.socket;
import core.sys.posix.netinet.in_;
import std.c.stdio;
void main() {
int sfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
int flag = 1;
size_t size;
setsockopt(sfd, SOL_SOCKET, SO_KEEPALIVE, &flag,
cast(socklen_t)flag.sizeof);
flag = 0;
getsockopt(sfd, SOL_SOCKET, SO_KEEPALIVE, &flag,
cast(socklen_t*)&size);
printf("%d\n", flag);
}
C version:
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>
int main() {
int sfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
int flag = 1;
size_t size;
setsockopt(sfd, SOL_SOCKET, SO_KEEPALIVE, &flag,
(socklen_t)sizeof(flag));
flag = 0;
getsockopt(sfd, SOL_SOCKET, SO_KEEPALIVE, &flag,
(socklen_t*)&size);
printf("%d\n", flag);
return 0;
}
Dlang version always prints 0, which means keepalive is not
enabled, while C version can almost display 1 all the time as
expected.
So is there anything wrong inside the code? If not, whose
behavior is correct?
Could you check the return value of "setsockopt"? Make sure it
returns 0 as an indicator of successful operation. If so, then we
can think about it further.
