diff options
| author | Pau Espin Pedrol <pespin@sysmocom.de> | 2023-03-09 13:09:03 +0100 |
|---|---|---|
| committer | Pau Espin Pedrol <pespin@sysmocom.de> | 2023-03-13 11:58:49 +0100 |
| commit | 06d1cff11a32166d5b894ebc5fb093fea549ce49 (patch) | |
| tree | 54e9bb8602c7ccb216b7af7bba558eb8a3549465 | |
| parent | c5b7d94e0f4a07b7191efe5182c97e408bca77a3 (diff) | |
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
| -rw-r--r-- | include/osmocom/bsc/gsm_data.h | 2 | ||||
| -rw-r--r-- | src/osmo-bsc/bsc_sccp.c | 19 |
2 files changed, 18 insertions, 3 deletions
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h index 268aa0cc8..cdf0f4322 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 30d4c4c94..431e194f8 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 @@ uint32_t bsc_sccp_inst_next_conn_id(struct osmo_sccp_instance *sccp) 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 bsc_sccp_inst_next_conn_id(struct osmo_sccp_instance *sccp) 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) { |