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gsm/gsm0480.c: introduce gsm0480_extract_ie_by_tag() 

In some cases, there is no need to parse the whole message,
e.g. during the conversion from DTAP to GSUP/MAP. This
function can be used to extract given IE from a message.

Change-Id: I3989d061903352473305f80712f1a1560d05df3d
This commit is contained in:
Vadim Yanitskiy 2018-06-11 03:51:11 +07:00
parent 11eb4b5add
commit 52e44121db
5 changed files with 172 additions and 0 deletions
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2
include/osmocom/gsm/gsm0480.h
View File

@ -91,6 +91,8 @@ struct ss_request {
uint8_t invoke_id;
};
int gsm0480_extract_ie_by_tag(const struct gsm48_hdr *hdr, uint16_t msg_len,
uint8_t **ie, uint16_t *ie_len, uint8_t ie_tag);
int gsm0480_decode_ss_request(const struct gsm48_hdr *hdr, uint16_t len,
struct ss_request *request);

88
src/gsm/gsm0480.c
View File

@ -33,6 +33,7 @@
#include <osmocom/gsm/protocol/gsm_04_80.h>
#include <string.h>
#include <errno.h>
static inline unsigned char *msgb_wrap_with_TL(struct msgb *msgb, uint8_t tag)
{
@ -214,6 +215,93 @@ static int parse_ss_for_bs_req(const uint8_t *ss_req_data,
uint16_t length,
struct ss_request *req);
/*! Get pointer to the IE of a given type
* \param[in] hdr Pointer to the message starting from header
* \param[in] msg_len Length of the whole message + header
* \param[out] ie External pointer to be set
* \param[out] ie_len External IE length variable
* \param[in] ie_tag Tag value of the required IE
* \returns 0 in case of success, otherwise -ERRNO
*
* This function iterates over existing IEs within a given
* message (depending on its type), and looks for the one with
* given \ref ie_tag value. If the IE is found, the external
* pointer pointed by \ref ie will be set to its value part
* (omitting TL), and \ref ie_len will be set to the length.
* Otherwise, e.g. in case of parsing error, both \ref ie
* and \ref ie_len are set to NULL and 0 respectively.
*/
int gsm0480_extract_ie_by_tag(const struct gsm48_hdr *hdr, uint16_t msg_len,
uint8_t **ie, uint16_t *ie_len, uint8_t ie_tag)
{
uint8_t pdisc, msg_type;
uint8_t *tlv, len;
/* Init external variables */
*ie_len = 0;
*ie = NULL;
/* Drop incomplete / corrupted messages */
if (msg_len < sizeof(*hdr))
return -EINVAL;
pdisc = gsm48_hdr_pdisc(hdr);
msg_type = gsm48_hdr_msg_type(hdr);
/* Drop non-SS related messages */
if (pdisc != GSM48_PDISC_NC_SS)
return -EINVAL;
len = msg_len - sizeof(*hdr);
tlv = (uint8_t *) hdr->data;
/* Parse a message depending on its type */
switch (msg_type) {
/* See table 2.5: RELEASE COMPLETE message content */
case GSM0480_MTYPE_RELEASE_COMPLETE:
/* See tables 2.3 and 2.4: REGISTER message content */
case GSM0480_MTYPE_REGISTER:
/* Iterate over TLV-based IEs */
while (len > 2) {
if (tlv[0] == ie_tag) {
*ie_len = tlv[1];
*ie = tlv + 2;
return 0;
}
len -= tlv[1] + 2;
tlv += tlv[1] + 2;
continue;
}
/* The Facility IE is mandatory for REGISTER */
if (msg_type == GSM0480_MTYPE_REGISTER)
if (ie_tag == GSM0480_IE_FACILITY)
return -EINVAL;
break;
/* See table 2.2: FACILITY message content */
case GSM0480_MTYPE_FACILITY:
/* There is no other IEs */
if (ie_tag != GSM0480_IE_FACILITY)
break;
/* Mandatory LV-based Facility IE */
if (len < 2)
return -EINVAL;
*ie_len = tlv[0];
*ie = tlv + 1;
return 0;
default:
/* Wrong message type, out of specs */
return -EINVAL;
}
return 0;
}
/* Decode a mobile-originated USSD-request message */
int gsm0480_decode_ussd_request(const struct gsm48_hdr *hdr, uint16_t len,
struct ussd_request *req)

1
src/gsm/libosmogsm.map
View File

@ -89,6 +89,7 @@ gsm0480_create_unstructuredSS_Notify;
gsm0480_create_ussd_resp;
gsm0480_create_ussd_notify;
gsm0480_create_ussd_release_complete;
gsm0480_extract_ie_by_tag;
gsm0480_decode_ussd_request;
gsm0480_decode_ss_request;
gsm0480_wrap_facility;

75
tests/ussd/ussd_test.c
View File

@ -34,6 +34,17 @@ static const uint8_t ussd_request[] = {
0x01, 0x7f, 0x01, 0x00
};
static const uint8_t ussd_facility[] = {
0x1b, 0x3a, 0x12, 0xa2, 0x10, 0x02, 0x01, 0x01,
0x30, 0x0b, 0x02, 0x01, 0x3c, 0x30, 0x06, 0x04,
0x01, 0x0f, 0x04, 0x01, 0x32
};
static const uint8_t ussd_release[] = {
0x8b, 0x2a, 0x1c, 0x08, 0xa3, 0x06, 0x02, 0x01,
0x05, 0x02, 0x01, 0x24
};
static const uint8_t interrogate_ss[] = {
0x0b, 0x7b, 0x1c, 0x0d, 0xa1, 0x0b, 0x02, 0x01,
0x03, 0x02, 0x01, 0x0e, 0x30, 0x03, 0x04, 0x01,
@ -116,6 +127,67 @@ static void test_7bit_ussd(const char *text, const char *encoded_hex, const char
}
}
static void test_extract_ie_by_tag(void)
{
uint16_t ie_len;
uint8_t *ie;
int rc;
printf("[i] Testing gsm0480_extract_ie_by_tag()\n");
/* REGISTER message with Facility IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_request,
sizeof(ussd_request), &ie, &ie_len, GSM0480_IE_FACILITY);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie != NULL && ie_len > 0);
printf("[?] REGISTER message with Facility IE "
"(len=%u): %s\n", ie_len, osmo_hexdump(ie, ie_len));
/* REGISTER message with SS version IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_request,
sizeof(ussd_request), &ie, &ie_len, GSM0480_IE_SS_VERSION);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie != NULL && ie_len > 0);
printf("[?] REGISTER message with SS version IE "
"(len=%u): %s\n", ie_len, osmo_hexdump(ie, ie_len));
/* REGISTER message with unknown IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_request,
sizeof(ussd_request), &ie, &ie_len, 0xff);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie == NULL && ie_len == 0);
/* FACILITY message with Facility IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_facility,
sizeof(ussd_facility), &ie, &ie_len, GSM0480_IE_FACILITY);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie != NULL && ie_len > 0);
printf("[?] FACILITY message with Facility IE "
"(len=%u): %s\n", ie_len, osmo_hexdump(ie, ie_len));
/* FACILITY message with unknown IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_facility,
sizeof(ussd_facility), &ie, &ie_len, 0xff);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie == NULL && ie_len == 0);
/* RELEASE COMPLETE message with Facility IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_release,
sizeof(ussd_release), &ie, &ie_len, GSM0480_IE_FACILITY);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie != NULL && ie_len > 0);
printf("[?] RELEASE COMPLETE message with Facility IE "
"(len=%u): %s\n", ie_len, osmo_hexdump(ie, ie_len));
/* RELEASE COMPLETE message without Facility IE */
rc = gsm0480_extract_ie_by_tag((struct gsm48_hdr *) ussd_release,
sizeof(struct gsm48_hdr), &ie, &ie_len, GSM0480_IE_FACILITY);
OSMO_ASSERT(rc == 0);
OSMO_ASSERT(ie == NULL && ie_len == 0);
printf("\n");
}
int main(int argc, char **argv)
{
struct ss_request req;
@ -126,6 +198,9 @@ int main(int argc, char **argv)
osmo_init_logging2(ctx, &info);
/* Test gsm0480_extract_ie_by_tag() */
test_extract_ie_by_tag();
memset(&req, 0, sizeof(req));
gsm0480_decode_ss_request((struct gsm48_hdr *) ussd_request,
sizeof(ussd_request), &req);

6
tests/ussd/ussd_test.ok
View File

@ -1,3 +1,9 @@
[i] Testing gsm0480_extract_ie_by_tag()
[?] REGISTER message with Facility IE (len=21): a1 13 02 01 03 02 01 3b 30 0b 04 01 0f 04 06 2a d5 4c 16 1b 01
[?] REGISTER message with SS version IE (len=1): 00
[?] FACILITY message with Facility IE (len=18): a2 10 02 01 01 30 0b 02 01 3c 30 06 04 01 0f 04 01 32
[?] RELEASE COMPLETE message with Facility IE (len=8): a3 06 02 01 05 02 01 24
Tested if it still works. Text was: **321#
interrogateSS CFU text..'' code 33
Testing parsing a USSD request and truncated versions