SIOCGSTAMP does not work ?

SIOCGSTAMP does not work ?

[Maciej Soltysiak]

Hi,

i was recently trying to use SIOCGSTAMP to get the date of the last packet
that arrived on the socket. like so:

	struct timeval tv;
	...
	ioctl(fd, SIOCGSTAMP, &tv);

Unfortunately no matter how i tried that i always got errno: ENOENT, which
is explained by `man 7 ip':
SIOCGSTAMP was called on a socket where no packet arrived.

Little browsing through the net/ipv4 dir showed that there is a macro
TCP_CHECK_TIMER(sk) that is being used around tcp.c, tcp_ipv4.c and
tcp_timer.c

More grepping showed that TCP_CHECK_TIMER(sk) defined in include/net/tcp.h
does absolutely nothing!

#define TCP_CHECK_TIMER(sk) do { } while (0)

The questions are:
1. Is this all really related?

2. Why is TCP_CHECK_TIMER not coded ?

Regards,
Maciej Soltysiak

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Re: SIOCGSTAMP does not work ?

[David S. Miller]

On Tue, 2003-01-21 at 07:44, Maciej Soltysiak wrote:
> 1. Is this all really related?

No.

> 2. Why is TCP_CHECK_TIMER not coded ?

It is a debugging check, it has nothing to do with SIOCGSTAMP.

Re: SIOCGSTAMP does not work ?

[Alex Riesen]

Maciej Soltysiak, Tue, Jan 21, 2003 18:03:34 +0100:
> > > i was recently trying to use SIOCGSTAMP to get the date of the last packet
> > > that arrived on the socket. like so:
> >
> > which kernel?
> 2.4.20
> 
> If you can, please try to get the timestamp on any socket using.
> 
> struct timeval tv;
> ...
> ioctl (s, SIOCGSTAMP, &tv);
> 

sorry for delay.


I don't think SIOCGSTAMP was designed to work on "any socket".
It retrieves the timestamp correctly for PF_PACKET sockets though.
I may want to look at the libpcap source.

-alex