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tlv_parser: Report *first* occurrence of repeated IEs 

Most GSM related specifications require the receiver to use the
*first* occurrence of repeated IEs.  The Osmocom TLV parser so
far did the opposite: It reported only the *last* occurrence in
case of repeated IEs.  Let's change our implementation to be
more in-line with relevant specs, such as 3GPP TS 24.008 8.6.3.

Change-Id: Icde09e075f68c842a7a96cf7160c8e44b77cf82d
This commit is contained in:
Harald Welte 2018-02-02 12:11:14 +01:00
parent 6de34ee46b
commit bf383a1d83
1 changed files with 7 additions and 2 deletions
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9
src/gsm/tlv_parser.c
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@ -276,8 +276,13 @@ int tlv_parse(struct tlv_parsed *dec, const struct tlv_definition *def,
&buf[ofs], buf_len-ofs);
if (rv < 0)
return rv;
dec->lv[tag].val = val;
dec->lv[tag].len = len;
/* Most GSM related protocols clearly indicate that in case of duplicate
* IEs, only the first occurrence shall be used, while any further occurrences
* shall be ignored. See e.g. 3GPP TS 24.008 Section 8.6.3 */
if (dec->lv[tag].val == NULL) {
dec->lv[tag].val = val;
dec->lv[tag].len = len;
}
ofs += rv;
num_parsed++;
}