diff options
| author | Miroslav Lichvar <mlichvar@redhat.com> | 2022-08-16 14:41:21 +0200 |
|---|---|---|
| committer | AndersBroman <a.broman58@gmail.com> | 2022-10-31 14:38:50 +0000 |
| commit | d892d284818df3a1a99510b91de6d00ccf2e2b5a (patch) | |
| tree | 5ee2064a431211b189c16eca963d4fe9dae17040 /epan/dissectors | |
| parent | b025c45cf324f977d5ba94173ba9a57663800d19 (diff) | |
NTP: Improve handling of poll and precision fields
The poll and precision fields in timing NTP messages are signed
integers.
Different NTP implementations have different minimum and maximum polling
intervals. Some can be configured even with negative values for
sub-second intervals (e.g. down to -7 for 1/128th of a second).
NTP clocks on modern systems and hardware typically have
a sub-microsecond precision.
Print all poll values. Add the raw precision and change the resolution
of the printed value to nanoseconds.
Diffstat (limited to 'epan/dissectors')
| -rw-r--r-- | epan/dissectors/packet-ntp.c | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/epan/dissectors/packet-ntp.c b/epan/dissectors/packet-ntp.c index 64772e4c8f..9b00e0fa85 100644 --- a/epan/dissectors/packet-ntp.c +++ b/epan/dissectors/packet-ntp.c @@ -1137,7 +1137,7 @@ static void dissect_ntp_std(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ntp_tree, ntp_conv_info_t *ntp_conv) { guint8 stratum; - guint8 ppoll; + gint8 ppoll; gint8 precision; guint32 rootdelay; double rootdelay_double; @@ -1211,21 +1211,17 @@ dissect_ntp_std(tvbuff_t *tvb, packet_info *pinfo, proto_tree *ntp_tree, ntp_con * between successive messages, in seconds to the nearest * power of two. */ - ppoll = tvb_get_guint8(tvb, 2); - if ((ppoll >= 4) && (ppoll <= 17)) { - proto_tree_add_uint_format_value(ntp_tree, hf_ntp_ppoll, tvb, 2, 1, - ppoll, "%u (%u seconds)", ppoll, 1 << ppoll); - } else { - proto_tree_add_uint_format_value(ntp_tree, hf_ntp_ppoll, tvb, 2, 1, - ppoll, "invalid (%u)", ppoll); - } + ppoll = tvb_get_gint8(tvb, 2); + proto_tree_add_int_format_value(ntp_tree, hf_ntp_ppoll, tvb, 2, 1, + ppoll, ppoll >= 0 ? "%d (%.0f seconds)" : "%d (%5.3f seconds)", + ppoll, pow(2, ppoll)); /* Precision, 1 byte field indicating the precision of the * local clock, in seconds to the nearest power of two. */ - precision = tvb_get_guint8(tvb, 3); - proto_tree_add_uint_format_value(ntp_tree, hf_ntp_precision, tvb, 3, 1, - (guint8)precision, "%8.6f seconds", pow(2, precision)); + precision = tvb_get_gint8(tvb, 3); + proto_tree_add_int_format_value(ntp_tree, hf_ntp_precision, tvb, 3, 1, + precision, "%d (%11.9f seconds)", precision, pow(2, precision)); /* Root Delay is a 32-bit signed fixed-point number indicating * the total roundtrip delay to the primary reference source, @@ -2646,10 +2642,10 @@ proto_register_ntp(void) "Peer Clock Stratum", "ntp.stratum", FT_UINT8, BASE_DEC|BASE_RANGE_STRING, RVALS(stratum_rvals), 0, NULL, HFILL }}, { &hf_ntp_ppoll, { - "Peer Polling Interval", "ntp.ppoll", FT_UINT8, BASE_DEC, + "Peer Polling Interval", "ntp.ppoll", FT_INT8, BASE_DEC, NULL, 0, "Maximum interval between successive messages", HFILL }}, { &hf_ntp_precision, { - "Peer Clock Precision", "ntp.precision", FT_UINT8, BASE_DEC, + "Peer Clock Precision", "ntp.precision", FT_INT8, BASE_DEC, NULL, 0, "The precision of the system clock", HFILL }}, { &hf_ntp_rootdelay, { "Root Delay", "ntp.rootdelay", FT_UINT32, BASE_DEC, |