pespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/31797 )

Change subject: bscc_sccp: Avoid allocating conn_id 0x00FFFFFF ......................................................................

bscc_sccp: Avoid allocating conn_id 0x00FFFFFF

The 0x00FFFFFF source local reference is reserved in M3UA/SCCP, hence avoid allocating a conn_id with that value since later on when reused as a source local reference it would fail to be encoded.

Change-Id: I5c62bbfa89140d754edccb4404503cb70d5fde89 --- M include/osmocom/bsc/gsm_data.h M src/osmo-bsc/bsc_sccp.c 2 files changed, 31 insertions(+), 3 deletions(-)

Approvals: fixeria: Looks good to me, but someone else must approve daniel: Looks good to me, but someone else must approve Jenkins Builder: Verified pespin: Looks good to me, approved

diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h index 268aa0c..cdf0f43 100644 --- a/include/osmocom/bsc/gsm_data.h +++ b/include/osmocom/bsc/gsm_data.h @@ -52,7 +52,7 @@ #define GSM_NY1_DEFAULT ((unsigned long)((GSM_T3124_MAX + GSM_NY1_REQ_DELTA)/GSM_T3105_DEFAULT + 1))

#define SCCP_CONN_ID_UNSET 0xFFFFFFFF -#define SCCP_CONN_ID_MAX 0x00FFFFFF +#define SCCP_CONN_ID_MAX 0x00FFFFFE

struct mgcp_client_conf; struct mgcp_client; diff --git a/src/osmo-bsc/bsc_sccp.c b/src/osmo-bsc/bsc_sccp.c index 30d4c4c..431e194 100644 --- a/src/osmo-bsc/bsc_sccp.c +++ b/src/osmo-bsc/bsc_sccp.c @@ -21,6 +21,8 @@ * */

+#include <osmocom/core/utils.h> + #include <osmocom/bsc/gsm_data.h> #include <osmocom/bsc/bsc_msc_data.h> #include <osmocom/bsc/lb.h> @@ -31,6 +33,17 @@ static uint32_t next_id = 1; int i;

+ /* SUA: RFC3868 sec 3.10.4: + * The source reference number is a 4 octet long integer. + * This is allocated by the source SUA instance. + * M3UA/SCCP: ITU-T Q.713 sec 3.3: + * The "source local reference" parameter field is a three-octet field containing a + * reference number which is generated and used by the local node to identify the + * connection section after the connection section is set up. + * The coding "all ones" is reserved for future use. + * Hence, let's simply use 24 bit ids to fit all link types (excluding 0x00ffffff). + */ + /* This looks really suboptimal, but in most cases the static next_id should indicate exactly the next unused * conn_id, and we only iterate all conns once to make super sure that it is not already in use. */

@@ -39,8 +52,10 @@ uint32_t conn_id = next_id; bool conn_id_already_used = false;

- /* Optimized modulo operation using bitwise AND: */ - next_id = (next_id + 1) & SCCP_CONN_ID_MAX; + /* Optimized modulo operation (% SCCP_CONN_ID_MAX) using bitwise AND plus CMP: */ + next_id = (next_id + 1) & 0x00FFFFFF; + if (OSMO_UNLIKELY(next_id == 0x00FFFFFF)) + next_id = 0;

llist_for_each_entry(conn, &bsc_gsmnet->subscr_conns, entry) { if (conn->sccp.msc && conn->sccp.msc->a.sccp == sccp) {