This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/OpenBSC@lists.osmocom.org/.
Holger Hans Peter Freyther holger at freyther.deOn Tue, Jul 30, 2013 at 08:03:49AM +0800, Harald Welte wrote:
>
> Sure, go ahead. that's what I meant by 'be brave' :)
The engineer in me.. used git gui blame on the file and I found the commit
that added the foreign tlli lookup.
commit f0901f0067e363c0ced6254db1b45a9771640412
Author: Harald Welte <laforge at gnumonks.org>
Date: Sun Dec 26 10:39:26 2010 +0100
[SGSN] Fix processing of RA Update Request regarding TLLI
In case we get a RA UPD REQ on a new cell (both served by the same
SGSN), the LLC stack should not allocate a ne LLE/LLME, as the latter
would reset the V(u)sent / V(u)recv to zero and make the MS discard
our responses.
Instead, whenever the LLC stack sees a foreign TLLI, it should always
convert it to the local TLLI before doing any lookup for a LLE/LLME.
I had to move some code around but what I essentialy do is.
1.) I do the lookup based on the tlli...
2.) if the tlli is foreign.. I convert it and make another lookup
3.) I create the LLME on the fly or return NULL
Or shall we do this... "oh we know this subscriber already" at a
higher level in GMM? E.g. notice that it is a routing area update...
and then free the new llme and do a tlli assignment for the foreign
tlli?
diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c
index c3bd9d2..b637acb 100644
--- a/openbsc/src/gprs/gprs_llc.c
+++ b/openbsc/src/gprs/gprs_llc.c
@@ -36,6 +36,54 @@
#include <openbsc/crc24.h>
#include <openbsc/sgsn.h>
+enum gprs_llc_cmd {
+ GPRS_LLC_NULL,
+ GPRS_LLC_RR,
+ GPRS_LLC_ACK,
+ GPRS_LLC_RNR,
+ GPRS_LLC_SACK,
+ GPRS_LLC_DM,
+ GPRS_LLC_DISC,
+ GPRS_LLC_UA,
+ GPRS_LLC_SABM,
+ GPRS_LLC_FRMR,
+ GPRS_LLC_XID,
+ GPRS_LLC_UI,
+};
+
+static const struct value_string llc_cmd_strs[] = {
+ { GPRS_LLC_NULL, "NULL" },
+ { GPRS_LLC_RR, "RR" },
+ { GPRS_LLC_ACK, "ACK" },
+ { GPRS_LLC_RNR, "RNR" },
+ { GPRS_LLC_SACK, "SACK" },
+ { GPRS_LLC_DM, "DM" },
+ { GPRS_LLC_DISC, "DISC" },
+ { GPRS_LLC_UA, "UA" },
+ { GPRS_LLC_SABM, "SABM" },
+ { GPRS_LLC_FRMR, "FRMR" },
+ { GPRS_LLC_XID, "XID" },
+ { GPRS_LLC_UI, "UI" },
+ { 0, NULL }
+};
+
+struct gprs_llc_hdr_parsed {
+ uint8_t sapi;
+ uint8_t is_cmd:1,
+ ack_req:1,
+ is_encrypted:1;
+ uint32_t seq_rx;
+ uint32_t seq_tx;
+ uint32_t fcs;
+ uint32_t fcs_calc;
+ uint8_t *data;
+ uint16_t data_len;
+ uint16_t crc_length;
+ enum gprs_llc_cmd cmd;
+};
+
+static struct gprs_llc_llme *llme_alloc(uint32_t tlli);
+
/* Entry function from upper level (LLC), asking us to transmit a BSSGP PDU
* to a remote MS (identified by TLLI) at a BTS identified by its BVCI and NSEI */
static int _bssgp_tx_dl_ud(struct msgb *msg, struct sgsn_mm_ctx *mmctx)
@@ -162,6 +210,43 @@ static struct gprs_llc_lle *lle_by_tlli_sapi(const uint32_t tlli, uint8_t sapi)
return NULL;
}
+/* lookup LLC Entity for RX based on DLCI (TLLI+SAPI tuple) */
+static struct gprs_llc_lle *lle_for_rx_by_tlli_sapi(const uint32_t tlli,
+ uint8_t sapi, enum gprs_llc_cmd cmd)
+{
+ struct gprs_llc_lle *lle;
+
+ /* We already know about this TLLI */
+ lle = lle_by_tlli_sapi(tlli, sapi);
+ if (lle)
+ return lle;
+
+ /* Maybe it is a routing area update but we already know this sapi? */
+ if (gprs_tlli_type(tlli) == TLLI_FOREIGN) {
+ lle = lle_by_tlli_sapi(tlli_foreign2local(tlli), sapi);
+ if (lle)
+ return lle;
+ }
+
+ /* 7.2.1.1 LLC belonging to unassigned TLLI+SAPI shall be discarded,
+ * except UID and XID frames with SAPI=1 */
+ if (sapi == GPRS_SAPI_GMM &&
+ (cmd == GPRS_LLC_XID || cmd == GPRS_LLC_UI)) {
+ struct gprs_llc_llme *llme;
+ /* FIXME: don't use the TLLI but the 0xFFFF unassigned? */
+ llme = llme_alloc(tlli);
+ LOGP(DLLC, LOGL_DEBUG, "LLC RX: unknown TLLI 0x%08x, "
+ "creating LLME on the fly\n", tlli);
+ lle = &llme->lle[sapi];
+ return lle;
+ }
+
+ LOGP(DLLC, LOGL_NOTICE,
+ "unknown TLLI(0x%08x)/SAPI(%d): Silently dropping\n",
+ tlli, sapi);
+ return NULL;
+}
+
static void lle_init(struct gprs_llc_llme *llme, uint8_t sapi)
{
struct gprs_llc_lle *lle = &llme->lle[sapi];
@@ -201,52 +286,6 @@ static void llme_free(struct gprs_llc_llme *llme)
talloc_free(llme);
}
-enum gprs_llc_cmd {
- GPRS_LLC_NULL,
- GPRS_LLC_RR,
- GPRS_LLC_ACK,
- GPRS_LLC_RNR,
- GPRS_LLC_SACK,
- GPRS_LLC_DM,
- GPRS_LLC_DISC,
- GPRS_LLC_UA,
- GPRS_LLC_SABM,
- GPRS_LLC_FRMR,
- GPRS_LLC_XID,
- GPRS_LLC_UI,
-};
-
-static const struct value_string llc_cmd_strs[] = {
- { GPRS_LLC_NULL, "NULL" },
- { GPRS_LLC_RR, "RR" },
- { GPRS_LLC_ACK, "ACK" },
- { GPRS_LLC_RNR, "RNR" },
- { GPRS_LLC_SACK, "SACK" },
- { GPRS_LLC_DM, "DM" },
- { GPRS_LLC_DISC, "DISC" },
- { GPRS_LLC_UA, "UA" },
- { GPRS_LLC_SABM, "SABM" },
- { GPRS_LLC_FRMR, "FRMR" },
- { GPRS_LLC_XID, "XID" },
- { GPRS_LLC_UI, "UI" },
- { 0, NULL }
-};
-
-struct gprs_llc_hdr_parsed {
- uint8_t sapi;
- uint8_t is_cmd:1,
- ack_req:1,
- is_encrypted:1;
- uint32_t seq_rx;
- uint32_t seq_tx;
- uint32_t fcs;
- uint32_t fcs_calc;
- uint8_t *data;
- uint16_t data_len;
- uint16_t crc_length;
- enum gprs_llc_cmd cmd;
-};
-
#define LLC_ALLOC_SIZE 16384
#define UI_HDR_LEN 3
#define N202 4
@@ -770,25 +809,9 @@ int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv)
}
/* find the LLC Entity for this TLLI+SAPI tuple */
- lle = lle_by_tlli_sapi(msgb_tlli(msg), llhp.sapi);
-
- /* 7.2.1.1 LLC belonging to unassigned TLLI+SAPI shall be discarded,
- * except UID and XID frames with SAPI=1 */
- if (!lle) {
- if (llhp.sapi == GPRS_SAPI_GMM &&
- (llhp.cmd == GPRS_LLC_XID || llhp.cmd == GPRS_LLC_UI)) {
- struct gprs_llc_llme *llme;
- /* FIXME: don't use the TLLI but the 0xFFFF unassigned? */
- llme = llme_alloc(msgb_tlli(msg));
- LOGP(DLLC, LOGL_DEBUG, "LLC RX: unknown TLLI 0x%08x, "
- "creating LLME on the fly\n", msgb_tlli(msg));
- lle = &llme->lle[llhp.sapi];
- } else {
- LOGP(DLLC, LOGL_NOTICE,
- "unknown TLLI/SAPI: Silently dropping\n");
- return 0;
- }
- }
+ lle = lle_for_rx_by_tlli_sapi(msgb_tlli(msg), llhp.sapi, llhp.cmd);
+ if (!lle)
+ return 0;
/* decrypt information field + FCS, if needed! */
if (llhp.is_encrypted) {