libmsc: make pitfall in gsm0408_dispatch() more obvious
The function gsm0408_dispatch() accepts a message buffer pointer
and accesses the l3h pointer. Even in a properly allocated
message buffer, this may lead into a segfault if the user forgets
to set the l3h pointer. This commit adds assertions to popup a
more expressive error message.
Change-Id: I43bd9bd1c170559aaa8dacaef25dba090744bcd5
diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 21bc2b8..90a0431 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -3216,13 +3216,17 @@
/* Main entry point for GSM 04.08/44.008 Layer 3 data (e.g. from the BSC). */
int gsm0408_dispatch(struct gsm_subscriber_connection *conn, struct msgb *msg)
{
- struct gsm48_hdr *gh = msgb_l3(msg);
- uint8_t pdisc = gsm48_hdr_pdisc(gh);
+ struct gsm48_hdr *gh;
+ uint8_t pdisc;
int rc = 0;
+ OSMO_ASSERT(msg->l3h)
OSMO_ASSERT(conn);
OSMO_ASSERT(msg);
+ gh = msgb_l3(msg);
+ pdisc = gsm48_hdr_pdisc(gh);
+
LOGP(DRLL, LOGL_DEBUG, "Dispatching 04.08 message %s (0x%x:0x%x)\n",
gsm48_pdisc_msgtype_name(pdisc, gsm48_hdr_msg_type(gh)),
pdisc, gsm48_hdr_msg_type(gh));