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gsm: add osmo_mobile_identity_decode_from_l3_buf() 

We have osmo_mobile_identity_decode_from_l3(), which takes a msgb as
argument, and decodes msg->l3h. Not all callers have their data in this
form. Offer a more flexible API for the same decoding.

For example, before the new function, osmo-hnbgw, which extracts a NAS
PDU from asn.1 packed data for CN pooling, would allocate a new msgb and
copy the NAS data just to pass a data pointer as argument.

Related: SYS#6412
Change-Id: I9bd99ccd01f0eedc091fe51687ff92ae1fdff60b
This commit is contained in:
Neels Hofmeyr 2023-05-03 02:13:16 +02:00 committed by neels
parent e4b84738b5
commit e25786ab6a
3 changed files with 32 additions and 12 deletions
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2
include/osmocom/gsm/gsm48.h
View File

@ -96,6 +96,8 @@ char *osmo_mobile_identity_to_str_c(void *ctx, const struct osmo_mobile_identity
int osmo_mobile_identity_cmp(const struct osmo_mobile_identity *a, const struct osmo_mobile_identity *b);
int osmo_mobile_identity_decode(struct osmo_mobile_identity *mi, const uint8_t *mi_data, uint8_t mi_len,
bool allow_hex);
int osmo_mobile_identity_decode_from_l3_buf(struct osmo_mobile_identity *mi, const uint8_t *l3_data, size_t l3_len,
bool allow_hex);
int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct msgb *msg, bool allow_hex);
int osmo_mobile_identity_encoded_len(const struct osmo_mobile_identity *mi, int *mi_digits);
int osmo_mobile_identity_encode_buf(uint8_t *buf, size_t buflen, const struct osmo_mobile_identity *mi, bool allow_hex);

41
src/gsm/gsm48.c
View File

@ -863,11 +863,13 @@ int osmo_mobile_identity_encode_msgb(struct msgb *msg, const struct osmo_mobile_
* osmo_mobile_identity.
*
* \param[out] mi Return buffer for decoded Mobile Identity.
* \param[in] msg The Complete Layer 3 message to extract from (LU, CM Service Req or Paging Resp).
* \param[in] l3_data The Complete Layer 3 message to extract from (LU, CM Service Req or Paging Resp).
* \param[in] l3_len Length of l3_data in bytes.
* \returns 0 on success, negative on error: return codes as defined in osmo_mobile_identity_decode(), or
* -ENOTSUP = not a Complete Layer 3 message,
*/
int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct msgb *msg, bool allow_hex)
int osmo_mobile_identity_decode_from_l3_buf(struct osmo_mobile_identity *mi, const uint8_t *l3_data, size_t l3_len,
bool allow_hex)
{
const struct gsm48_hdr *gh;
int8_t pdisc = 0;
@ -886,10 +888,10 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
.tmsi = GSM_RESERVED_TMSI,
};
if (msgb_l3len(msg) < sizeof(*gh))
if (l3_len < sizeof(*gh))
return -EBADMSG;
gh = msgb_l3(msg);
gh = (void *)l3_data;
pdisc = gsm48_hdr_pdisc(gh);
mtype = gsm48_hdr_msg_type(gh);
@ -899,12 +901,12 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
switch (mtype) {
case GSM48_MT_MM_LOC_UPD_REQUEST:
/* First make sure that lu-> can be dereferenced */
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*lu))
if (l3_len < sizeof(*gh) + sizeof(*lu))
return -EBADMSG;
/* Now we know there is enough msgb data to read a lu->mi_len, so also check that */
lu = (struct gsm48_loc_upd_req*)gh->data;
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*lu) + lu->mi_len)
if (l3_len < sizeof(*gh) + sizeof(*lu) + lu->mi_len)
return -EBADMSG;
mi_data = lu->mi;
mi_len = lu->mi_len;
@ -914,7 +916,7 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
case GSM48_MT_MM_CM_REEST_REQ:
/* Unfortunately in Phase1 the Classmark2 length is variable, so we cannot
* just use gsm48_service_request struct, and need to parse it manually. */
if (msgb_l3len(msg) < sizeof(*gh) + 2)
if (l3_len < sizeof(*gh) + 2)
return -EBADMSG;
cm2_len = gh->data[1];
@ -922,7 +924,7 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
goto got_cm2;
case GSM48_MT_MM_IMSI_DETACH_IND:
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*idi))
if (l3_len < sizeof(*gh) + sizeof(*idi))
return -EBADMSG;
idi = (struct gsm48_imsi_detach_ind*) gh->data;
mi_data = idi->mi;
@ -930,7 +932,7 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
goto got_mi;
case GSM48_MT_MM_ID_RESP:
if (msgb_l3len(msg) < sizeof(*gh) + 2)
if (l3_len < sizeof(*gh) + 2)
return -EBADMSG;
mi_data = gh->data+1;
mi_len = gh->data[0];
@ -945,7 +947,7 @@ int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct
switch (mtype) {
case GSM48_MT_RR_PAG_RESP:
if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*paging_response))
if (l3_len < sizeof(*gh) + sizeof(*paging_response))
return -EBADMSG;
paging_response = (struct gsm48_pag_resp*)gh->data;
cm2_len = paging_response->cm2_len;
@ -964,7 +966,7 @@ got_cm2:
/* MI (Mobile Identity) LV follows the Classmark2 */
/* There must be at least a mi_len byte after the CM2 */
if (cm2_buf + cm2_len + 1 > msg->tail)
if (cm2_buf + cm2_len + 1 > l3_data + l3_len)
return -EBADMSG;
mi_start = cm2_buf + cm2_len;
@ -973,12 +975,27 @@ got_cm2:
got_mi:
/* mi_data points at the start of the Mobile Identity coding of mi_len bytes */
if (mi_data + mi_len > msg->tail)
if (mi_data + mi_len > l3_data + l3_len)
return -EBADMSG;
return osmo_mobile_identity_decode(mi, mi_data, mi_len, allow_hex);
}
/*! Extract Mobile Identity from a Complete Layer 3 message.
*
* Determine the Mobile Identity data and call osmo_mobile_identity_decode() to return a decoded struct
* osmo_mobile_identity.
*
* \param[out] mi Return buffer for decoded Mobile Identity.
* \param[in] msg The Complete Layer 3 message to extract from (LU, CM Service Req or Paging Resp).
* \returns 0 on success, negative on error: return codes as defined in osmo_mobile_identity_decode(), or
* -ENOTSUP = not a Complete Layer 3 message,
*/
int osmo_mobile_identity_decode_from_l3(struct osmo_mobile_identity *mi, struct msgb *msg, bool allow_hex)
{
return osmo_mobile_identity_decode_from_l3_buf(mi, msgb_l3(msg), msgb_l3len(msg), allow_hex);
}
/*! Return a human readable representation of a struct osmo_mobile_identity.
* Write a string like "IMSI-1234567", "TMSI-0x1234ABCD" or "NONE", "NULL".
* \param[out] buf String buffer to write to.

1
src/gsm/libosmogsm.map
View File

@ -391,6 +391,7 @@ osmo_mobile_identity_to_str_buf;
osmo_mobile_identity_to_str_c;
osmo_mobile_identity_cmp;
osmo_mobile_identity_decode;
osmo_mobile_identity_decode_from_l3_buf;
osmo_mobile_identity_decode_from_l3;
osmo_mobile_identity_encoded_len;
osmo_mobile_identity_encode_buf;