Common library for all Osmocom projects (libosmocore, libosmogsm, libosmovty, libosmogb, libosmosim, libosmousb, ...) https://osmocom.org/projects/libosmocore
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libosmocore/src/gsm/tlv_parser.c

179 lines
3.9 KiB

#include <stdio.h>
#include <stdint.h>
#include <osmocore/utils.h>
#include <osmocore/tlv.h>
struct tlv_definition tvlv_att_def;
int tlv_dump(struct tlv_parsed *dec)
{
int i;
for (i = 0; i <= 0xff; i++) {
if (!dec->lv[i].val)
continue;
printf("T=%02x L=%d\n", i, dec->lv[i].len);
}
return 0;
}
/* o_tag: output: tag found
* o_len: output: length of the data
* o_val: output: pointer to the data
* def: input: a structure defining the valid TLV tags / configurations
* buf: input: the input data buffer to be parsed
* buf_len: input: the length of the input data buffer
*
* Also, returns the number of bytes consumed by the TLV entry
*/
int tlv_parse_one(uint8_t *o_tag, uint16_t *o_len, const uint8_t **o_val,
const struct tlv_definition *def,
const uint8_t *buf, int buf_len)
{
uint8_t tag;
int len;
tag = *buf;
*o_tag = tag;
/* single octet TV IE */
if (def->def[tag & 0xf0].type == TLV_TYPE_SINGLE_TV) {
*o_tag = tag & 0xf0;
*o_val = buf;
*o_len = 1;
return 1;
}
/* FIXME: use tables for knwon IEI */
switch (def->def[tag].type) {
case TLV_TYPE_T:
/* GSM TS 04.07 11.2.4: Type 1 TV or Type 2 T */
*o_val = buf;
*o_len = 0;
len = 1;
break;
case TLV_TYPE_TV:
*o_val = buf+1;
*o_len = 1;
len = 2;
break;
case TLV_TYPE_FIXED:
*o_val = buf+1;
*o_len = def->def[tag].fixed_len;
len = def->def[tag].fixed_len + 1;
break;
case TLV_TYPE_TLV:
/* GSM TS 04.07 11.2.4: Type 4 TLV */
if (buf + 1 > buf + buf_len)
return -1;
*o_val = buf+2;
*o_len = *(buf+1);
len = *o_len + 2;
if (len > buf_len)
return -2;
break;
case TLV_TYPE_TvLV:
if (*(buf+1) & 0x80) {
/* like TLV, but without highest bit of len */
if (buf + 1 > buf + buf_len)
return -1;
*o_val = buf+2;
*o_len = *(buf+1) & 0x7f;
len = *o_len + 2;
if (len > buf_len)
return -2;
break;
}
/* like TL16V, fallthrough */
case TLV_TYPE_TL16V:
if (2 > buf_len)
return -1;
*o_val = buf+3;
*o_len = *(buf+1) << 8 | *(buf+2);
len = *o_len + 3;
if (len > buf_len)
return -2;
break;
default:
return -3;
}
return len;
}
/* dec: output: a caller-allocated pointer to a struct tlv_parsed,
* def: input: a structure defining the valid TLV tags / configurations
* buf: input: the input data buffer to be parsed
* buf_len: input: the length of the input data buffer
* lv_tag: input: an initial LV tag at the start of the buffer
* lv_tag2: input: a second initial LV tag following lv_tag
*/
int tlv_parse(struct tlv_parsed *dec, const struct tlv_definition *def,
const uint8_t *buf, int buf_len, uint8_t lv_tag,
uint8_t lv_tag2)
{
int ofs = 0, num_parsed = 0;
uint16_t len;
memset(dec, 0, sizeof(*dec));
if (lv_tag) {
if (ofs > buf_len)
return -1;
dec->lv[lv_tag].val = &buf[ofs+1];
dec->lv[lv_tag].len = buf[ofs];
len = dec->lv[lv_tag].len + 1;
if (ofs + len > buf_len)
return -2;
num_parsed++;
ofs += len;
}
if (lv_tag2) {
if (ofs > buf_len)
return -1;
dec->lv[lv_tag2].val = &buf[ofs+1];
dec->lv[lv_tag2].len = buf[ofs];
len = dec->lv[lv_tag2].len + 1;
if (ofs + len > buf_len)
return -2;
num_parsed++;
ofs += len;
}
while (ofs < buf_len) {
int rv;
uint8_t tag;
const uint8_t *val;
rv = tlv_parse_one(&tag, &len, &val, def,
&buf[ofs], buf_len-ofs);
if (rv < 0)
return rv;
dec->lv[tag].val = val;
dec->lv[tag].len = len;
ofs += rv;
num_parsed++;
}
//tlv_dump(dec);
return num_parsed;
}
/* take a master (src) tlvdev and fill up all empty slots in 'dst' */
void tlv_def_patch(struct tlv_definition *dst, const struct tlv_definition *src)
{
int i;
for (i = 0; i < ARRAY_SIZE(dst->def); i++) {
if (src->def[i].type == TLV_TYPE_NONE)
continue;
if (dst->def[i].type == TLV_TYPE_NONE)
dst->def[i] = src->def[i];
}
}
static __attribute__((constructor)) void on_dso_load_tlv(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(tvlv_att_def.def); i++)
tvlv_att_def.def[i].type = TLV_TYPE_TvLV;
}