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gtp.sai_sac field size limitation

asked 2018-12-07 07:36:28 +0000

rom gravatar image

updated 2018-12-07 10:48:28 +0000

grahamb gravatar image

I can not use a filter for gtp.sai_sac if sai_sac is greater than ff. gtp.sai_sac == 50072 isn't a valid display filter: "50072" too big for this field, maximum 255. 50072 is a really value from pcap. wireshark version 2.6.4

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answered 2018-12-07 10:41:28 +0000

Jaap gravatar image

There seems to be a discrepancy between the use of the "sai_sac" field and the registration of this field. The use is based on a 2 octet value (proto_tree_add_item(tree, hf_gtp_sai_sac, tvb, offset, 2, ENC_BIG_ENDIAN);) while the registration is for a 1 octet value (..."Service Area Code (SAC)", "gtp.sai_sac", FT_UINT8, BASE_DEC,...). "gtp.rai_rac" suffers this same fate.

Please file a bug report, attaching a sample capture file showing this issue, so that it can be fixed in a later release.

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Anders gravatar imageAnders ( 2018-12-07 12:16:15 +0000 )edit
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answered 2018-12-07 10:44:02 +0000

grahamb gravatar image

updated 2018-12-07 10:44:50 +0000

Looks like a bug, the field definition in the gtp dissector source has it as a FT_UINT8, but the dissection reads 2 bytes from the packet:

{&hf_gtp_cgi_ci,
 { "Cell ID (CI)", "gtp.cgi_ci",
   FT_UINT8, BASE_DEC, NULL, 0,
   NULL, HFILL}
},
{&hf_gtp_sai_sac,
 { "Service Area Code (SAC)", "gtp.sai_sac",
   FT_UINT8, BASE_DEC, NULL, 0,
   NULL, HFILL}
},
{&hf_gtp_rai_rac,
 { "Routing Area Code (RAC)", "gtp.rai_rac",
   FT_UINT8, BASE_DEC, NULL, 0,
   NULL, HFILL}
},

gtp.cgi_ci and gtp.rai_rac seem to be similarly afflicted. Please raise a bug entry at our bugzilla.

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Asked: 2018-12-07 07:36:28 +0000

Seen: 23 times

Last updated: Dec 07