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feat(#19647): decode resolution fields

This commit is contained in:
marmonier_c 2024-02-19 09:02:09 +01:00 committed by AndersBroman
parent f501c57fc3
commit 1703eea653
1 changed files with 69 additions and 17 deletions
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86
epan/dissectors/packet-lldp.c
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@ -1457,7 +1457,7 @@ get_latitude_or_longitude(gchar *buf, int option, guint64 unmasked_value)
gboolean isNegative = get2sComplementAbsoluteValue(&absolute_value, variableBitSize);
// Get unsigned integer 8-bit value
guint32 integerPortion = absolute_value >> fractionnalBitSize;
guint32 integerPortion = (guint32)(absolute_value >> fractionnalBitSize);
// Get fractionnal 25-bit value
const guint numberOfDigitToDisplay = 4;
@ -1531,15 +1531,6 @@ altitude_base(gchar *buf, guint32 unmasked_value) {
// the altitude resolution (AltRes) value encodes the number of
// high-order altitude bits that should be considered valid.
// Values above 30 (decimal) are undefined and reserved.
//
// The encoded altitude of 000000000000000010000110110011 decodes to
// 33.69921875. The encoded uncertainty of 15 gives a value of 64;
// therefore, the final uncertainty is 33.69921875 +/- 64 (or the range
// from -30.30078125 to 97.69921875).
// The amount of altitude uncertainty can be determined by the following
// formula, where x is the encoded integer value:
// Uncertainty = 2 ^ ( 21 - x )
// = 2 ^ ( 21 - 15 ) = 2 ^ 6 = 64
const guint variableBitSize = 30;
const guint fractionnalBitSize = 8;
@ -1552,7 +1543,7 @@ altitude_base(gchar *buf, guint32 unmasked_value) {
gboolean isNegative = get2sComplementAbsoluteValue(&absolute_value, variableBitSize);
// Get unsigned integer 8-bit value
guint32 integerPortion = absolute_value >> fractionnalBitSize;
guint32 integerPortion = (guint32)(absolute_value >> fractionnalBitSize);
// Get fractionnal 8-bit value
const guint numberOfDigitToDisplay = 4;
@ -1576,6 +1567,67 @@ altitude_base(gchar *buf, guint32 unmasked_value) {
);
}
static void
latitude_or_longitude_resolution(gchar *buf, guint8 value) {
// formula, where x is the encoded integer value:
// Uncertainty = 2 ^ ( 8 - x )
gint32 masked_value = value & 0x3F;
double resolution = 1.0;
gint32 i = 8 - masked_value;
while(i > 0){
resolution *= 2.0;
i--;
}
while(i < 0){
resolution /= 2.0;
i++;
}
const char *err_str = "";
if(masked_value > 34){
err_str = "[Error: value > 34] ";
} else if(masked_value < 2){
err_str = "[Warning: value < 2] ";
}
snprintf(buf, ITEM_LABEL_LENGTH, "%s%lE degrees (%" PRIi32 ")", err_str, resolution, masked_value);
}
static void
altitude_resolution(gchar *buf, guint8 value) {
// The encoded altitude of 000000000000000010000110110011 decodes to
// 33.69921875. The encoded uncertainty of 15 gives a value of 64;
// therefore, the final uncertainty is 33.69921875 +/- 64 (or the range
// from -30.30078125 to 97.69921875).
// The amount of altitude uncertainty can be determined by the following
// formula, where x is the encoded integer value:
// Uncertainty = 2 ^ ( 21 - x )
// = 2 ^ ( 21 - 15 ) = 2 ^ 6 = 64
gint32 masked_value = value & 0x3F;
double resolution = 1.0;
gint32 i = 21 - masked_value;
while(i > 0){
resolution *= 2.0;
i--;
}
while(i < 0){
resolution /= 2.0;
i++;
}
const char *err_str = "";
if(masked_value > 30){
err_str = "[Error: value > 34] ";
} else if(masked_value < 2){
err_str = "[Warning: value < 2] ";
}
snprintf(buf, ITEM_LABEL_LENGTH, "%s%lf (%" PRIi32 ")", err_str, resolution, masked_value);
}
/* Dissect Chassis Id TLV (Mandatory) */
static gint32
dissect_lldp_chassis_id(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 offset,
@ -5989,16 +6041,16 @@ proto_register_lldp(void)
VALS(location_data_format), 0x0, NULL, HFILL }
},
{ &hf_media_loc_lat_resolution,
{ "Latitude Resolution", "lldp.media.loc.lat_resolution", FT_UINT8, BASE_DEC,
NULL, 0xFC, NULL, HFILL }
{ "Latitude Resolution", "lldp.media.loc.lat_resolution", FT_UINT8, BASE_CUSTOM,
CF_FUNC(latitude_or_longitude_resolution), 0xFC, NULL, HFILL }
},
{ &hf_media_loc_lat,
{ "Latitude", "lldp.media.loc.latitude", FT_UINT40, BASE_CUSTOM,
CF_FUNC(latitude_base), 0x0, NULL, HFILL }
},
{ &hf_media_loc_long_resolution,
{ "Longitude Resolution", "lldp.media.loc.long_resolution", FT_UINT8, BASE_DEC,
NULL, 0xFC, NULL, HFILL }
{ "Longitude Resolution", "lldp.media.loc.long_resolution", FT_UINT8, BASE_CUSTOM,
CF_FUNC(latitude_or_longitude_resolution), 0xFC, NULL, HFILL }
},
{ &hf_media_loc_long,
{ "Longitude", "lldp.media.loc.longitude", FT_UINT40, BASE_CUSTOM,
@ -6009,8 +6061,8 @@ proto_register_lldp(void)
VALS(altitude_type), 0xF0, "Unknown", HFILL }
},
{ &hf_media_loc_alt_resolution,
{ "Altitude Resolution", "lldp.media.loc.alt_resolution", FT_UINT16, BASE_DEC,
NULL, 0x0FC0, NULL, HFILL }
{ "Altitude Resolution", "lldp.media.loc.alt_resolution", FT_UINT16, BASE_CUSTOM,
CF_FUNC(altitude_resolution), 0x0FC0, NULL, HFILL }
},
{ &hf_media_loc_alt,
{ "Altitude", "lldp.media.loc.altitude", FT_UINT32, BASE_CUSTOM,