Re: [RFC PATCH 2/2] tcpdump: hw timestamp support

["Mcmillan, Scott A" <scott.a.mcmillan () intel com>]

This is an updated patch for tcpdump-4.1.1 to add the capability to select hw timestamps via the -j command line 
option.  The usage has been simplified: -j now takes no argument, and uses the hw timestamp transformed into the system 
clock basis corresponding to "-j nic" from the previous patch.

I left the more generic libpcap infrastructure in place to support future extensions that may want more precise 
selection of the timestamp source.

Thanks to Zhuo Yin who pointed out that I omitted netdissect.h from the original patch.

I will upload both patches to SourceForge once the PACKET_TIMESTAMP patch is accepted by the Linux netdev maintainer.

Signed-off-by: Scott McMillan <scott.a.mcmillan () intel com>

--- a/tcpdump-4.1.1/interface.h 2010-03-11 19:56:44.000000000 -0600
+++ b/tcpdump-4.1.1/interface.h 2010-05-18 14:10:32.000000000 -0500
@@ -356,6 +356,7 @@
 #define bflag gndo->ndo_bflag 
 #define eflag gndo->ndo_eflag 
 #define fflag gndo->ndo_fflag 
+#define jflag gndo->ndo_jflag
 #define Kflag gndo->ndo_Kflag 
 #define nflag gndo->ndo_nflag 
 #define Nflag gndo->ndo_Nflag 
--- a/tcpdump-4.1.1/netdissect.h        2010-03-11 19:56:44.000000000 -0600
+++ b/tcpdump-4.1.1/netdissect.h        2010-05-18 14:10:32.000000000 -0500
@@ -107,6 +107,7 @@
   int ndo_Iflag;               /* rfmon (monitor) mode */
   int ndo_Oflag;                /* run filter code optimizer */
   int ndo_dlt;                  /* if != -1, ask libpcap for the DLT it names*/
+  int ndo_jflag;               /* packet time source */
   int ndo_pflag;                /* don't go promiscuous */
 
   int ndo_Cflag;                /* rotate dump files after this many bytes */ 
--- a/tcpdump-4.1.1/tcpdump.c   2010-03-11 19:56:44.000000000 -0600
+++ b/tcpdump-4.1.1/tcpdump.c   2010-05-27 10:10:58.000000000 -0500
@@ -74,6 +74,9 @@
 #include <errno.h>
 #endif /* WIN32 */
 
+#ifdef HAVE_LINUX_NET_TSTAMP_H
+#include <linux/net_tstamp.h>
+#endif /* HAVE_LINUX_NET_TSTAMP_H */
 
 #include "netdissect.h"
 #include "interface.h"
@@ -600,7 +603,7 @@
 
        opterr = 0;
        while (
-           (op = getopt(argc, argv, "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:" I_FLAG "KlLm:M:nNOpqr:Rs:StT:u" U_FLAG 
"vw:W:xXy:Yz:Z:")) != -1)
+           (op = getopt(argc, argv, "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:i:" I_FLAG "jKlLm:M:nNOpqr:Rs:StT:u" U_FLAG 
"vw:W:xXy:Yz:Z:")) != -1)
                switch (op) {
 
                case 'a':
@@ -740,6 +743,14 @@
                        break;
 #endif /* HAVE_PCAP_CREATE */
 
+               case 'j':
+#ifdef HAVE_LINUX_NET_TSTAMP_H
+                       jflag = SOF_TIMESTAMPING_SYS_HARDWARE;
+#else
+                       warning("not compiled with hw timestamp support");
+#endif /* HAVE_LINUX_NET_TSTAMP_H */
+                       break;
+
                case 'l':
 #ifdef WIN32
                        /*
@@ -1063,6 +1074,12 @@
                                error("%s: pcap_set_buffer_size failed: %s",
                                    device, pcap_statustostr(status));
                }
+                if (jflag != 0) {
+                       status = pcap_set_timesource(pd, jflag);
+                       if (status != 0)
+                               warning("%s: pcap_set_timesource failed: %s",
+                                   device, pcap_statustostr(status));
+               }
                status = pcap_activate(pd);
                if (status < 0) {
                        /*
--- a/tcpdump-4.1.1/configure.in        2010-04-05 20:18:35.000000000 -0500
+++ b/tcpdump-4.1.1/configure.in        2010-05-18 14:10:32.000000000 -0500
@@ -1076,6 +1076,16 @@
        fi
 fi
 
+dnl check for hardware timestamp support
+case "$host_os" in
+linux*)
+       AC_CHECK_HEADERS([linux/net_tstamp.h])
+       ;;
+*)
+       AC_MSG_NOTICE(no hardware timestamp support)
+       ;;
+esac
+
 dnl
 dnl set additional include path if necessary
 if test "$missing_includes" = "yes"; then
-
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