[PATCH 1/4] gprs: Fix and check BVCI in BSSGP STATUS messages

[Jacob Erlbeck]

Currently the BVCI is not set in all invocations to bssgp_tx_status()
when the cause is UNKNOWN_BVCI.

This patch adds the argument where it is missing.

It also adds a check for compliance (GSM 08.18, 10.4.14.1) to
bssgp_tx_status() to emit errors when the following requirement is
not fulfilled: The BVCI must be included if (and only if) the cause
is either "BVCI blocked" or "BVCI unknown".

Sponsored-by: On-Waves ehf
---
src/gb/gprs_bssgp.c | 2 +-
src/gb/gprs_bssgp_util.c | 14 ++++++++++++++
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/gb/gprs_bssgp.c b/src/gb/gprs_bssgp.c
index 5ef1887..b8c6c74 100644
--- a/src/gb/gprs_bssgp.c
+++ b/src/gb/gprs_bssgp.c
@@ -998,7 +998,7 @@ int bssgp_rcvmsg(struct msgb *msg)
LOGP(DBSSGP, LOGL_NOTICE, "NSEI=%u/BVCI=%u Rejecting PDU "
"type %u for unknown BVCI\n", msgb_nsei(msg), ns_bvci,
pdu_type);
- return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, NULL, msg);
+ return bssgp_tx_status(BSSGP_CAUSE_UNKNOWN_BVCI, &ns_bvci, msg);
}

if (bctx) {
diff --git a/src/gb/gprs_bssgp_util.c b/src/gb/gprs_bssgp_util.c
index ae4647e..261e0b0 100644
--- a/src/gb/gprs_bssgp_util.c
+++ b/src/gb/gprs_bssgp_util.c
@@ -99,6 +99,20 @@ int bssgp_tx_status(uint8_t cause, uint16_t *bvci, struct msgb *orig_msg)
struct bssgp_normal_hdr *bgph =
(struct bssgp_normal_hdr *) msgb_put(msg, sizeof(*bgph));

+ /* GSM 08.18, 10.4.14.1: The BVCI must be included if (and only if) the
+ cause is either "BVCI blocked" or "BVCI unknown" */
+ if (cause == BSSGP_CAUSE_UNKNOWN_BVCI || cause == BSSGP_CAUSE_BVCI_BLOCKED) {
+ if (bvci == NULL)
+ LOGP(DBSSGP, LOGL_ERROR, "BSSGP Tx STATUS, cause=%s: "
+ "missing conditional BVCI\n",
+ bssgp_cause_str(cause));
+ } else {
+ if (bvci != NULL)
+ LOGP(DBSSGP, LOGL_ERROR, "BSSGP Tx STATUS, cause=%s: "
+ "unexpected conditional BVCI\n",
+ bssgp_cause_str(cause));
+ }
+
LOGP(DBSSGP, LOGL_NOTICE, "BSSGP BVCI=%u Tx STATUS, cause=%s\n",
bvci ? *bvci : 0, bssgp_cause_str(cause));
msgb_nsei(msg) = msgb_nsei(orig_msg);