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Add support for setting the time stamp type for a capture.

Based on a patch from Scott Mcmillan <scott.a.mcmillan@intel.com>.
master
Guy Harris 12 years ago
parent 0ba94d1cfa
commit 951f99bbbd
  1. 126
      pcap-tstamp.manmisc.in
  2. 70
      pcap_list_tstamp_types.3pcap.in
  3. 63
      pcap_set_tstamp_type.3pcap.in
  4. 45
      pcap_tstamp_type_name_to_val.3pcap
  5. 45
      pcap_tstamp_type_val_to_name.3pcap

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.\"
.\" Copyright (c) 1987, 1988, 1989, 1990, 1991, 1992, 1994, 1995, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP-TSTAMP @MAN_MISC_INFO@ "22 August 2010"
.SH NAME
pcap-tstamp \- packet time stamps in libpcap
.SH DESCRIPTION
When capturing traffic, each packet is given a time stamp representing,
for incoming packets, the arrival time of the packet and, for outgoing
packets, the transmission time of the packet. This time is an
approximation of the arrival or transmission time. If it is supplied by
the operating system running on the host on which the capture is being
done, there are several reasons why it might not precisely represent the
arrival or transmission time:
.IP
if the time stamp is applied to the packet when the networking stack
receives the packet, the networking stack might not see the packet until
an interrupt is delivered for the packet or a timer event causes the
networking device driver to poll for packets, and the time stamp might
not be applied until the packet has had some processing done by other
code in the networking stack, so there might be a significant delay
between the time when the last bit of the packet is received by the
capture device and when the networking stack time-stamps the packet;
.IP
the timer used to generate the time stamps might have low resolution,
for example, it might be a timer updated once per host operating system
timer tick, with the host operating system timer ticking once every few
milliseconds;
.IP
a high-resolution timer might use a counter that runs at a rate
dependent on the processor clock speed, and that clock speed might be
adjusted upwards or downwards over time and the timer might not be able
to compensate for all those adjustments;
.IP
the host operating system's clock might be adjusted over time to match a
time standard to which the host is being synchronized, which might be
done by temporarily slowing down or speeding up the clock or by making a
single adjustment;
.IP
different CPU cores on a multi-core or multi-processor system might be
running at different speeds, or might not have time counters all
synchronized, so packets time-stamped by different cores might not have
consistent time stamps.
.LP
In addition, packets time-stamped by different cores might be
time-stamped in one order and added to the queue of packets for libpcap
to read in another order, so time stamps might not be monotonically
increasing.
.LP
Some capture devices on some platforms can provide time stamps for
packets; those time stamps are usually high-resolution time stamps, and
are usually applied to the packet when the first or last bit of the
packet arrives, and are thus more accurate than time stamps provided by
the host operating system. Those time stamps might not, however, be
synchronized with the host operating system's clock, so that, for
example, the time stamp of a packet might not correspond to the time
stamp of an event on the host triggered by the arrival of that packet.
.LP
Depending on the capture device and the software on the host, libpcap
might allow different types of time stamp to be used. The
.BR pcap_list_tstamp_types (3PCAP)
routine provides, for a packet capture handle created by
.BR pcap_create (3PCAP)
but not yet activated by
.BR pcap_activate (3PCAP),
a list of time stamp types supported by the capture device for that
handle.
The list might be empty, in which case no choice of time stamp type is
offered for that capture device. If the list is not empty, the
.BR pcap_set_tstamp_type (3PCAP)
routine can be used after a
.B pcap_create()
call and before a
.B pcap_activate()
call to specify the type of time stamp to be used on the device.
The time stamp types are:
.RS 5
.TP 5
.BR PCAP_TSTAMP_HOST
Time stamp provided by the host on which the capture is being done. The
precision of this time stamp is unspecified; it might or might not be
synchronized with the host operating system's clock.
.TP 5
.BR PCAP_TSTAMP_HOST_LOWPREC
Time stamp provided by the host on which the capture is being done.
This is a low-precision time stamp, synchronized with the host operating
system's clock.
.TP 5
.BR PCAP_TSTAMP_HOST_HIPREC
Time stamp provided by the host on which the capture is being done.
This is a high-precision time stamp; it might or might not be
synchronized with the host operating system's clock. It might be more
expensive to fetch than
.BR PCAP_TSTAMP_HOST_LOWPREC .
.TP 5
.BR PCAP_TSTAMP_ADAPTER
Time stamp provided by the network adapter on which the capture is being
done. This is a high-precision time stamp, synchronized with the host
operating system's clock.
.TP 5
.BR PCAP_TSTAMP_ADAPTER_UNSYNC
Time stamp provided by the network adapter on which the capture is being
done. This is a high-precision time stamp; it is not synchronized with
the host operating system's clock.
.RE
.SH SEE ALSO
pcap_set_tstamp_type(3PCAP),
pcap_list_tstamp_types(3PCAP)

@ -0,0 +1,70 @@
.\"
.\" Copyright (c) 1994, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_LIST_TSTAMP_TYPES 3PCAP "21 August 2010"
.SH NAME
pcap_list_tstamp_types, pcap_free_tstamp_types \- get a list of time
stamp types supported by a capture device, and free that list
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_list_tstamp_types(pcap_t *p, int **tstamp_typesp);
void pcap_free_tstamp_types(int *tstamp_types);
.ft
.fi
.SH DESCRIPTION
.B pcap_list_tstamp_types()
is used to get a list of the supported time stamp types of the interface
associated with the pcap descriptor.
.B pcap_list_tstamp_types()
allocates an array to hold the list and sets
.I *tstamp_typesp
to point to the array.
See
.BR pcap-tstamp (@MAN_MISC_INFO@)
for a list of all the time stamp types.
.PP
The caller is responsible for freeing the array with
.BR pcap_free_tstamp_types() ,
which frees the list pointed to by
.IR tstamp_types .
.SH RETURN VALUE
.B pcap_list_tstamp_types()
returns the number of time stamp types in the array on success and
.B PCAP_ERROR
on failure.
A return value of zero means that you cannot specify a time stamp type;
you are limited to the capture device's default time stamp type.
If
.B PCAP_ERROR
is returned,
.B pcap_geterr()
or
.B pcap_perror()
may be called with
.I p
as an argument to fetch or display the error text.
.SH SEE ALSO
pcap(3PCAP), pcap_geterr(3PCAP), pcap_tstamp_type_val_to_name(3PCAP),
pcap-tstamp(@MAN_MISC_INFO@)

@ -0,0 +1,63 @@
.\"
.\" Copyright (c) 1994, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_SET_TSTAMP_TYPE 3PCAP "21 August 2010"
.SH NAME
pcap_set_tstamp_type \- set the time stamp type to be used by a
capture device
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_set_tstamp_type(pcap_t *p, int tstamp_type);
.ft
.fi
.SH DESCRIPTION
.B pcap_set_tstamp_type()
sets the the type of time stamp desired for packets captured on the pcap
descriptor to the type specified by
.IR tstamp_type .
It must be called on a pcap descriptor created by
.B pcap_create()
that has not yet been activated by
.BR pcap_activate() .
.B pcap_list_tstamp_types()
will give a list of the time stamp types supported by a given capture
device.
See
.BR pcap-tstamp (@MAN_MISC_INFO@)
for a list of all the time stamp types.
.SH RETURN VALUE
.B pcap_set_tstamp_type()
returns 0 on success,
.B PCAP_ERROR_ACTIVATED
if called on a capture handle that has been activated,
.B PCAP_ERROR_CANTSET_TSTAMP_TYPE
if the capture device doesn't support setting the time stamp type, and
.B PCAP_ERROR_TSTAMP_TYPE_NOTSUP
if the specified time stamp type is not supported by the capture device.
.SH SEE ALSO
pcap(3PCAP),
pcap_list_tstamp_types(3PCAP),
pcap_tstamp_type_name_to_val(3PCAP),
pcap-tstamp(@MAN_MISC_INFO@)

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.\"
.\" Copyright (c) 1994, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_TSTAMP_TYPE_NAME_TO_VAL 3PCAP "21 August 2010"
.SH NAME
pcap_tstamp_type_name_to_val \- get the time stamp type value
corresponding to a time stamp type name
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_tstamp_type_name_to_val(const char *name);
.ft
.fi
.SH DESCRIPTION
.B pcap_tstamp_type_name_to_val()
translates a time stamp type name to the corresponding time stamp type
value. The translation is case-insensitive.
.SH RETURN VALUE
.B pcap_tstamp_type_name_to_val()
returns 0 on success and
.B PCAP_ERROR
on failure.
.SH SEE ALSO
pcap(3PCAP), pcap_tstamp_type_val_to_name(3PCAP)

@ -0,0 +1,45 @@
.\"
.\" Copyright (c) 1994, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_TSTAMP_TYPE_VAL_TO_NAME 3PCAP "21 August 2010"
.SH NAME
pcap_tstamp_type_val_to_name, pcap_tstamp_type_val_to_description \- get
a name or description for a time stamp type value
.SH SYNOPSIS
.nf
.ft B
#include <pcap.h>
.ft
.LP
.ft B
const char *pcap_tstamp_type_val_to_name(int tstamp_type);
const char *pcap_tstamp_type_val_to_description(int tstamp_type);
.ft
.fi
.SH DESCRIPTION
.B pcap_tstamp_type_val_to_name()
translates a time stamp type value to the corresponding time stamp type
name. NULL is returned on failure.
.PP
.B pcap_tstamp_type_val_to_description()
translates a time stamp type value to a short description of that time
stamp type. NULL is returned on failure.
.SH SEE ALSO
pcap(3PCAP), pcap_tstamp_type_name_to_val(3PCAP)