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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>.
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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) |
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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_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@) |
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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_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) |
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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_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) |