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How to read values of type 'Label'

asked May 23 '19

adamiaonr gravatar image

updated May 23 '19

I'm experiencing an issue for which I couldn't find an answer in Google.

I'm interested in the values of the field wlan.vht.compressed_beamforming_report.phi ('PHI'), which according to the display field reference guide is of type 'Label' and available in versions 2.4.0 to 3.0.2 (mine is 2.6.9, so I assume that's ok).

To display the values of 'PHI' in a column, I right-click on the value in the packet details pane, and choose the option 'Apply as column'.

However, the value that shows up in the column is a simple 'tick', while the value in the packet details pane is very different (e.g., check this screenshot, with the expected value highlighted in the packet details pane).

My questions are:

  • What exactly is the protocol field type 'Label'?
  • Why isn't the 'correct' value showing up in the column after I do 'Apply as column'?
  • I've checked that if I right-click on the value in the packet details pane and choose 'Copy' > 'Description', the pasted value is the expected one. Is it possible to make the 'Description' appear in the column instead?

Wireshark version: Version 2.6.9 (v2.6.9-0-gf1627e90)

OS: Mac OS X 10.11.5

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answered May 30 '19

Guy Harris gravatar image

The answer to the remaining question is "you can't". The 802.11 dissector does not provide the quantized angle values as named, typed fields; Copy > Description just copies the raw text, and the column mechanism doesn't currently support that.

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Thanks, that's what I thought!

I ended up exporting the raw hex string of the 'vht compressed beamforming report' as a column, and then parsed it myself using a Python script.

In order to understand how the parsing was done, I've analyzed the Wireshark source code and looked into the IEEE 802.11ac specification.

adamiaonr gravatar imageadamiaonr ( May 31 '19 )
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answered May 24 '19

Hi,

Guy Harris already answered a similar question and does a better job than I can.

Cheers,

JF

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Thank you for the pointer! However, that answer doesn't answer the remaining questions, more specifically how to display the value that one sees in packet details in a column.

adamiaonr gravatar imageadamiaonr ( May 24 '19 )

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Asked: May 23 '19

Seen: 713 times

Last updated: May 30 '19