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gprs_llc: Work on finding the right LLE/LLME in case of routing area update 

Attempt to solve what f0901f0067 tried to
solve without breaking the case of someone with a foreign TLLI from a
different network.

Lookup with the foreign TLLI converted to a local one in case we did
not find the TLLI and only then create a LLE/LLME on the fly for the
RX path.
This commit is contained in:
Holger Hans Peter Freyther 2013-07-30 09:29:27 +02:00
parent 012a7eec29
commit 964a9b3e20
1 changed files with 94 additions and 65 deletions
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159
openbsc/src/gprs/gprs_llc.c
View File

@ -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)
@ -158,6 +206,47 @@ 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) {
LOGP(DLLC, LOGL_NOTICE,
"LLC RX: Found a local entry for TLLI 0x%08x\n",
tlli);
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];
@ -197,52 +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
@ -360,6 +403,8 @@ int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
/* look-up or create the LL Entity for this (TLLI, SAPI) tuple */
lle = lle_by_tlli_sapi(msgb_tlli(msg), sapi);
if (!lle)
lle = lle_by_tlli_sapi(tlli_foreign2local(msgb_tlli(msg)), sapi);
if (!lle) {
struct gprs_llc_llme *llme;
LOGP(DLLC, LOGL_ERROR, "LLC TX: unknown TLLI 0x%08x, "
@ -766,25 +811,9 @@ 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) {