From bf383a1d83661af26ccd6521c49b655fb22531d4 Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Fri, 2 Feb 2018 12:11:14 +0100 Subject: 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 --- src/gsm/tlv_parser.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'src/gsm') diff --git a/src/gsm/tlv_parser.c b/src/gsm/tlv_parser.c index 9b1fb17a..b8c7149f 100644 --- a/src/gsm/tlv_parser.c +++ b/src/gsm/tlv_parser.c @@ -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++; } -- cgit v1.2.3