Re: [RFC PATCH 1/2] libpcap: linux hw timestamp

[Darren Reed <darren.reed () oracle com>]

Scott,

How does "-j raw" generate different output to "-j nic"?

Looking through your code below, the code which constructs
the data to pass through with the SIOCHWSTAMP ioctl ignores
the "timesource" member completely (except to check if it is
zero or not and thus turn it on.)  This is the change to
pcap-linux.c. By inspection, it looks buggy (or incomplete.)

Is there some code missing, below, where "hwconfig" is
filled out or is this really just an on/off thing at present?

Do you have some output to show how the output of "-j raw"
is different to that of "-j nic"?

Darren

On 24/05/10 07:26 AM, Mcmillan, Scott A wrote:
> [My apologies if this double posts.  The mail server didn't care for the first submission.]
>
> This patch adds the general infrastructure needed to select the packet timestamp source as well as specific support for 
> the PACKET_TIMESTAMP Linux kernel setting.
>
> Signed-off-by: Scott McMillan<scott.a.mcmillan () intel com>
>
> --- a/libpcap-1.1.1/pcap/pcap.h 2010-03-11 19:56:54.000000000 -0600
> +++ b/libpcap-1.1.1/pcap/pcap.h 2010-05-18 14:07:43.000000000 -0500
> @@ -259,6 +259,7 @@
>    */
>   #define PCAP_WARNING                  1       /* generic warning code */
>   #define PCAP_WARNING_PROMISC_NOTSUP   2       /* this device doesn't support promiscuous mode */
> +#define PCAP_WARNING_HWTSTAMP_NOTSUP   3       /* hardware timestamps are not supported */
>
>   /*
>    * Value to pass to pcap_compile() as the netmask if you don't know what
> --- a/libpcap-1.1.1/pcap-int.h  2010-03-11 19:56:54.000000000 -0600
> +++ b/libpcap-1.1.1/pcap-int.h  2010-05-18 14:07:43.000000000 -0500
> @@ -265,6 +265,10 @@
>
>         int break_loop;         /* flag set to force break from packet-reading loop */
>
> +#ifdef HAVE_LINUX_NET_TSTAMP_H
> +       int timesource;   /* select the timesource for the packet timestamp */
> +#endif /* HAVE_LINUX_NET_TSTAMP_H */
> +
>   #ifdef PCAP_FDDIPAD
>         int fddipad;
>   #endif
> --- a/libpcap-1.1.1/pcap-linux.c        2010-03-11 19:56:54.000000000 -0600
> +++ b/libpcap-1.1.1/pcap-linux.c        2010-05-18 16:44:45.000000000 -0500
> @@ -138,6 +138,11 @@
>   #include<poll.h>
>   #include<dirent.h>
>
> +#ifdef HAVE_LINUX_NET_TSTAMP_H
> +#include<linux/net_tstamp.h>
> +#include<linux/sockios.h>
> +#endif
> +
>   /*
>    * Got Wireless Extensions?
>    */
> @@ -3078,6 +3083,48 @@
>
>         frames_per_block = req.tp_block_size/req.tp_frame_size;
>
> +#ifdef HAVE_LINUX_NET_TSTAMP_H
> +       /* ask the kernel to use hardware timestamps */
> +       if (handle->timesource != 0) {
> +#ifdef SIOCSHWTSTAMP
> +               struct hwtstamp_config hwconfig;
> +               struct ifreq ifr;
> +
> +               memset(&hwconfig, 0, sizeof(hwconfig));
> +               hwconfig.tx_type = HWTSTAMP_TX_ON;
> +               hwconfig.rx_filter = HWTSTAMP_FILTER_ALL;
> +
> +               memset(&ifr, 0, sizeof(ifr));
> +               strcpy(ifr.ifr_name, handle->opt.source);
> +               ifr.ifr_data = (void *)&hwconfig;
> +
> +               if(ioctl(handle->fd, SIOCSHWTSTAMP,&ifr)<  0) {
> +                       snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
> +                               "can't set SIOCSHWTSTAMP %d: %d-%s",
> +                               handle->fd, errno, pcap_strerror(errno));
> +               }
> +#else
> +               snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
> +                       "SIOCSHWTSTAMP not supported %d: %d-%s",
> +                       handle->fd, errno, pcap_strerror(errno));
> +#endif /* SIOCSHWTSTAMP */
> +
> +#ifdef PACKET_TIMESTAMP
> +               if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP,
> +                       (void *)&handle->timesource,
> +                       sizeof(handle->timesource))) {
> +                       snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
> +                               "can't set PACKET_TIMESTAMP %d: %d-%s",
> +                               handle->fd, errno, pcap_strerror(errno));
> +               }
> +#else
> +               snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
> +                       "PACKET_TIMESTAMP not supported: %d: %d-%s",
> +                       handle->fd, errno, pcap_strerror(errno));
> +#endif
> +       }
> +#endif /* HAVE_LINUX_NET_TSTAMP_H */
> +
>         /* ask the kernel to create the ring */
>   retry:
>         req.tp_block_nr = req.tp_frame_nr / frames_per_block;
> --- a/libpcap-1.1.1/pcap.c      2010-03-11 19:56:54.000000000 -0600
> +++ b/libpcap-1.1.1/pcap.c      2010-05-18 14:07:43.000000000 -0500
> @@ -309,6 +309,19 @@
>   }
>
>   int
> +pcap_set_timesource(pcap_t *p, int timesource)
> +{
> +#ifdef HAVE_LINUX_NET_TSTAMP_H
> +       if (pcap_check_activated(p))
> +               return PCAP_ERROR_ACTIVATED;
> +       p->timesource = timesource;
> +       return 0;
> +#else
> +       return PCAP_WARNING_HWTSTAMP_NOTSUP;
> +#endif /* HAVE_LINUX_NET_TSTAMP_H */
> +}
> +
> +int
>   pcap_set_buffer_size(pcap_t *p, int buffer_size)
>   {
>         if (pcap_check_activated(p))
> @@ -979,6 +992,9 @@
>         case PCAP_WARNING_PROMISC_NOTSUP:
>                 return ("That device doesn't support promiscuous mode");
>
> +       case PCAP_WARNING_HWTSTAMP_NOTSUP:
> +               return ("Hardware timestamps are not supported");
> +
>         case PCAP_ERROR:
>                 return("Generic error");
>
> --- a/libpcap-1.1.1/configure.in        2010-03-11 19:56:53.000000000 -0600
> +++ b/libpcap-1.1.1/configure.in        2010-05-18 14:07:43.000000000 -0500
> @@ -1416,6 +1416,16 @@
>         AC_SUBST(CAN_SRC)
>   fi
>
> +dnl check for hardware timestamp support
> +case "$host_os" in
> +linux*)
> +       AC_CHECK_HEADERS([linux/net_tstamp.h])
> +       ;;
> +*)
> +       AC_MSG_NOTICE(no hardware timestamp support)
> +       ;;
> +esac
> +
>   AC_PROG_INSTALL
>
>   AC_CONFIG_HEADER(config.h)
> -
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-
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