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authorHarald Welte <laforge@osmocom.org>2020-11-18 11:57:42 +0100
committerHarald Welte <laforge@osmocom.org>2020-11-24 11:33:16 +0100
commit952fbf20c9f14afbf0f9ccc9d7d7bdf9c15e86e5 (patch)
tree050b6bb3689ef1dc493e8e96ef6d18f640a3b6a3
parent8553f5532ac7182506845abea0f40e92d5149f24 (diff)
gprs_gb_parse: Add function to determine TLLI from encoded BSSGP
This will be needed to use the TLLI as link selector parameter in osmo-gbproxy in an upcoming patch. Depends: libosmocore.git I397b32a6e6ea3e9d218446138cceafa9b27685dd Change-Id: Ia6d5300e63ad23987cbdca824db620305bd583d7
-rw-r--r--include/osmocom/sgsn/gprs_gb_parse.h2
-rw-r--r--src/gprs/gprs_gb_parse.c41
2 files changed, 43 insertions, 0 deletions
diff --git a/include/osmocom/sgsn/gprs_gb_parse.h b/include/osmocom/sgsn/gprs_gb_parse.h
index 9f43faed..58de17f8 100644
--- a/include/osmocom/sgsn/gprs_gb_parse.h
+++ b/include/osmocom/sgsn/gprs_gb_parse.h
@@ -51,6 +51,8 @@ int gprs_gb_parse_llc(uint8_t *llc, size_t llc_len,
int gprs_gb_parse_bssgp(uint8_t *bssgp, size_t bssgp_len,
struct gprs_gb_parse_context *parse_ctx);
+int gprs_gb_parse_tlli(const uint8_t *bssgp, size_t bssgp_len, uint32_t *tlli);
+
const char *gprs_gb_message_name(const struct gprs_gb_parse_context *parse_ctx,
const char *default_msg_name);
diff --git a/src/gprs/gprs_gb_parse.c b/src/gprs/gprs_gb_parse.c
index e5de4d4c..e6a82acb 100644
--- a/src/gprs/gprs_gb_parse.c
+++ b/src/gprs/gprs_gb_parse.c
@@ -437,6 +437,47 @@ int gprs_gb_parse_llc(uint8_t *llc, size_t llc_len,
return gprs_gb_parse_dtap(ghp->data, ghp->data_len, parse_ctx);
}
+/*! Determine the TLLI from the given BSSGP message.
+ * \param[in] bssgp pointer to start of BSSGP header
+ * \param[in] bssgp_len length of BSSGP message in octets
+ * \param[out] tlli TLLI (if any) in host byte order
+ * \returns 1 if TLLI found; 0 if none found; negative on parse error */
+int gprs_gb_parse_tlli(const uint8_t *bssgp, size_t bssgp_len, uint32_t *tlli)
+{
+ const struct bssgp_normal_hdr *bgph;
+ uint8_t pdu_type;
+
+ if (bssgp_len < sizeof(struct bssgp_normal_hdr))
+ return -EINVAL;
+
+ bgph = (struct bssgp_normal_hdr *)bssgp;
+ pdu_type = bgph->pdu_type;
+
+ if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+ pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+ const struct bssgp_ud_hdr *budh = (struct bssgp_ud_hdr *)bssgp;
+ if (bssgp_len < sizeof(struct bssgp_ud_hdr))
+ return -EINVAL;
+ *tlli = osmo_load32be((const uint8_t *)&budh->tlli);
+ return 1;
+ } else {
+ const uint8_t *data = bgph->data;
+ size_t data_len = bssgp_len - sizeof(*bgph);
+ struct tlv_parsed tp;
+
+ if (bssgp_tlv_parse(&tp, data, data_len) < 0)
+ return -EINVAL;
+
+ if (TLVP_PRESENT(&tp, BSSGP_IE_TLLI)) {
+ *tlli = osmo_load32be(TLVP_VAL(&tp, BSSGP_IE_TLLI));
+ return 1;
+ }
+ }
+
+ /* No TLLI present in message */
+ return 0;
+}
+
int gprs_gb_parse_bssgp(uint8_t *bssgp, size_t bssgp_len,
struct gprs_gb_parse_context *parse_ctx)
{