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libosmocore/src/gsm/gad.c

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/* 3GPP TS 23.032 GAD: Universal Geographical Area Description */
/*
* (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
*
* All Rights Reserved
*
* Author: Neels Hofmeyr <neels@hofmeyr.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <errno.h>
#include <inttypes.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/utils.h>
#include <osmocom/gsm/gad.h>
/*! \addtogroup gad
* @{
* \file gad.c
* Message encoding and decoding for 3GPP TS 23.032 GAD: Universal Geographical Area Description.
*/
const struct value_string osmo_gad_type_names[] = {
{ GAD_TYPE_ELL_POINT, "Ellipsoid-point" },
{ GAD_TYPE_ELL_POINT_UNC_CIRCLE, "Ellipsoid-point-with-uncertainty-circle" },
{ GAD_TYPE_ELL_POINT_UNC_ELLIPSE, "Ellipsoid-point-with-uncertainty-ellipse" },
{ GAD_TYPE_POLYGON, "Polygon" },
{ GAD_TYPE_ELL_POINT_ALT, "Ellipsoid-point-with-altitude" },
{ GAD_TYPE_ELL_POINT_ALT_UNC_ELL, "Ellipsoid-point-with-altitude-and-uncertainty-ellipsoid" },
{ GAD_TYPE_ELL_ARC, "Ellipsoid-arc" },
{ GAD_TYPE_HA_ELL_POINT_UNC_ELLIPSE, "High-accuracy-ellipsoid-point-with-uncertainty-ellipse" },
{ GAD_TYPE_HA_ELL_POINT_ALT_UNC_ELL, "High-accuracy-ellipsoid-point-with-altitude-and-uncertainty-ellipsoid" },
{}
};
/*! Encode a latitude value according to 3GPP TS 23.032.
* Useful to clamp a latitude to an actually encodable accuracy:
* set_lat = osmo_gad_dec_lat(osmo_gad_enc_lat(orig_lat));
* \param[in] deg_1e6 Latitude in micro degrees (degrees * 1e6), -90'000'000 (S) .. 90'000'000 (N).
* \returns encoded latitude in host-byte-order (24bit).
*/
uint32_t osmo_gad_enc_lat(int32_t deg_1e6)
{
/* N <= ((2**23)/90)*X < N+1
* N: encoded latitude
* X: latitude in degrees
*/
int32_t sign = 0;
int64_t x;
deg_1e6 = OSMO_MAX(-90000000, OSMO_MIN(90000000, deg_1e6));
if (deg_1e6 < 0) {
sign = 1 << 23;
deg_1e6 = -deg_1e6;
}
x = deg_1e6;
x <<= 23;
x += (1 << 23) - 1;
x /= 90 * 1000000;
return sign | (x & 0x7fffff);
}
/*! Decode a latitude value according to 3GPP TS 23.032.
* Useful to clamp a latitude to an actually encodable accuracy:
* set_lat = osmo_gad_dec_lat(osmo_gad_enc_lat(orig_lat));
* \param[in] lat encoded latitude in host-byte-order (24bit).
* \returns decoded latitude in micro degrees (degrees * 1e6), -90'000'000 (S) .. 90'000'000 (N).
*/
int32_t osmo_gad_dec_lat(uint32_t lat)
{
int64_t sign = 1;
int64_t x;
if (lat & 0x800000) {
sign = -1;
lat &= 0x7fffff;
}
x = lat;
x *= 90 * 1000000;
x >>= 23;
x *= sign;
return x;
}
/*! Encode a longitude value according to 3GPP TS 23.032.
* Useful to clamp a longitude to an actually encodable accuracy:
* set_lon = osmo_gad_dec_lon(osmo_gad_enc_lon(orig_lon));
* \param[in] deg_1e6 Longitude in micro degrees (degrees * 1e6), -180'000'000 (W) .. 180'000'000 (E).
* \returns encoded longitude in host-byte-order (24bit).
*/
uint32_t osmo_gad_enc_lon(int32_t deg_1e6)
{
/* -180 .. 180 degrees mapped to a signed 24 bit integer.
* N <= ((2**24)/360) * X < N+1
* N: encoded longitude
* X: longitude in degrees
*/
int64_t x;
deg_1e6 = OSMO_MAX(-180000000, OSMO_MIN(180000000, deg_1e6));
x = deg_1e6;
x *= (1 << 24);
if (deg_1e6 >= 0)
x += (1 << 24) - 1;
else
x -= (1 << 24) - 1;
x /= 360 * 1000000;
return (uint32_t)(x & 0xffffff);
}
/*! Decode a longitude value according to 3GPP TS 23.032.
* Normally, encoding and decoding is done via osmo_gad_enc() and osmo_gad_dec() for entire PDUs. But calling this
* directly can be useful to clamp a longitude to an actually encodable accuracy:
* int32_t set_lon = osmo_gad_dec_lon(osmo_gad_enc_lon(orig_lon));
* \param[in] lon Encoded longitude.
* \returns Longitude in micro degrees (degrees * 1e6), -180'000'000 (W) .. 180'000'000 (E).
*/
int32_t osmo_gad_dec_lon(uint32_t lon)
{
/* -180 .. 180 degrees mapped to a signed 24 bit integer.
* N <= ((2**24)/360) * X < N+1
* N: encoded longitude
* X: longitude in degrees
*/
int32_t slon;
int64_t x;
if (lon & 0x800000) {
/* make the 24bit negative number to a 32bit negative number */
slon = lon | 0xff000000;
} else {
slon = lon;
}
x = slon;
x *= 360 * 1000000;
x /= (1 << 24);
return x;
}
/*
* r = C((1+x)**K - 1)
* C = 10, x = 0.1
*
* def r(k):
* return 10.*(((1+0.1)**k) -1 )
* for k in range(128):
* print('%d,' % (r(k) * 1000.))
*/
static uint32_t table_uncertainty_1e3[128] = {
0, 1000, 2100, 3310, 4641, 6105, 7715, 9487, 11435, 13579, 15937, 18531, 21384, 24522, 27974, 31772, 35949,
40544, 45599, 51159, 57274, 64002, 71402, 79543, 88497, 98347, 109181, 121099, 134209, 148630, 164494, 181943,
201137, 222251, 245476, 271024, 299126, 330039, 364043, 401447, 442592, 487851, 537636, 592400, 652640, 718904,
791795, 871974, 960172, 1057189, 1163908, 1281299, 1410429, 1552472, 1708719, 1880591, 2069650, 2277615,
2506377, 2758014, 3034816, 3339298, 3674227, 4042650, 4447915, 4893707, 5384077, 5923485, 6516834, 7169517,
7887469, 8677216, 9545938, 10501531, 11552685, 12708953, 13980849, 15379933, 16918927, 18611820, 20474002,
22522402, 24775642, 27254206, 29980627, 32979690, 36278659, 39907525, 43899277, 48290205, 53120226, 58433248,
64277573, 70706330, 77777964, 85556760, 94113436, 103525780, 113879358, 125268293, 137796123, 151576735,
166735409, 183409950, 201751945, 221928139, 244121953, 268535149, 295389664, 324929630, 357423593, 393166952,
432484648, 475734112, 523308524, 575640376, 633205414, 696526955, 766180651, 842799716, 927080688, 1019789756,
1121769732, 1233947705, 1357343476, 1493078824, 1642387706, 1806627477,
};
/*! Decode an uncertainty circle value according to 3GPP TS 23.032.
* Useful to clamp a value to an actually encodable accuracy:
* set_unc = osmo_gad_dec_unc(osmo_gad_enc_unc(orig_unc));
* \param[in] unc Encoded uncertainty value.
* \returns Uncertainty value in millimeters.
*/
uint32_t osmo_gad_dec_unc(uint8_t unc)
{
return table_uncertainty_1e3[unc & 0x7f];
}
/*! Encode an uncertainty circle value according to 3GPP TS 23.032.
* Normally, encoding and decoding is done via osmo_gad_enc() and osmo_gad_dec() for entire PDUs. But calling this
* directly can be useful to clamp a value to an actually encodable accuracy:
* uint32_t set_unc = osmo_gad_dec_unc(osmo_gad_enc_unc(orig_unc));
* \param[in] mm Uncertainty value in millimeters.
* \returns Encoded uncertainty value.
*/
uint8_t osmo_gad_enc_unc(uint32_t mm)
{
uint8_t unc;
for (unc = 0; unc < ARRAY_SIZE(table_uncertainty_1e3); unc++) {
if (table_uncertainty_1e3[unc] > mm)
return unc - 1;
}
return 127;
}
/* So far we don't encode a high-accuracy uncertainty anywhere, so these static items would flag as compiler warnings
* for unused items. As soon as any HA items get used, remove this ifdef. */
#ifdef GAD_FUTURE
/*
* r = C((1+x)**K - 1)
* C = 0.3, x = 0.02
*
* def r(k):
* return 0.3*(((1+0.02)**k) -1 )
* for k in range(256):
* print('%d,' % (r(k) * 1000.))
*/
static uint32_t table_ha_uncertainty_1e3[256] = {
0, 6, 12, 18, 24, 31, 37, 44, 51, 58, 65, 73, 80, 88, 95, 103, 111, 120, 128, 137, 145, 154, 163, 173, 182, 192,
202, 212, 222, 232, 243, 254, 265, 276, 288, 299, 311, 324, 336, 349, 362, 375, 389, 402, 417, 431, 445, 460,
476, 491, 507, 523, 540, 556, 574, 591, 609, 627, 646, 665, 684, 703, 724, 744, 765, 786, 808, 830, 853, 876,
899, 923, 948, 973, 998, 1024, 1051, 1078, 1105, 1133, 1162, 1191, 1221, 1252, 1283, 1314, 1347, 1380, 1413,
1447, 1482, 1518, 1554, 1592, 1629, 1668, 1707, 1748, 1788, 1830, 1873, 1916, 1961, 2006, 2052, 2099, 2147,
2196, 2246, 2297, 2349, 2402, 2456, 2511, 2567, 2625, 2683, 2743, 2804, 2866, 2929, 2994, 3060, 3127, 3195,
3265, 3336, 3409, 3483, 3559, 3636, 3715, 3795, 3877, 3961, 4046, 4133, 4222, 4312, 4404, 4498, 4594, 4692,
4792, 4894, 4998, 5104, 5212, 5322, 5435, 5549, 5666, 5786, 5907, 6032, 6158, 6287, 6419, 6554, 6691, 6830,
6973, 7119, 7267, 7418, 7573, 7730, 7891, 8055, 8222, 8392, 8566, 8743, 8924, 9109, 9297, 9489, 9685, 9884,
10088, 10296, 10508, 10724, 10944, 11169, 11399, 11633, 11871, 12115, 12363, 12616, 12875, 13138, 13407, 13681,
13961, 14246, 14537, 14834, 15136, 15445, 15760, 16081, 16409, 16743, 17084, 17431, 17786, 18148, 18517, 18893,
19277, 19669, 20068, 20475, 20891, 21315, 21747, 22188, 22638, 23096, 23564, 24042, 24529, 25025, 25532, 26048,
26575, 27113, 27661, 28220, 28791, 29372, 29966, 30571, 31189, 31818, 32461, 33116, 33784, 34466, 35161, 35871,
36594, 37332, 38085, 38852, 39635, 40434, 41249, 42080, 42927, 43792, 44674, 45573, 46491,
};
static uint32_t osmo_gad_dec_ha_unc(uint8_t unc)
{
return table_uncertainty_1e3[unc];
}
static uint8_t osmo_gad_enc_ha_unc(uint32_t mm)
{
uint8_t unc;
for (unc = 0; unc < ARRAY_SIZE(table_ha_uncertainty_1e3); unc++) {
if (table_uncertainty_1e3[unc] > mm)
return unc - 1;
}
return 255;
}
#endif /* GAD_FUTURE */
/* Return error code, and, if required, allocate and populate struct osmo_gad_err. */
#define DEC_ERR(RC, TYPE, fmt, args...) do { \
if (err) { \
*err = talloc_zero(err_ctx, struct osmo_gad_err); \
**err = (struct osmo_gad_err){ \
.rc = (RC), \
.type = (TYPE), \
.logmsg = talloc_asprintf(*err, "Error decoding GAD%s%s: " fmt, \
((int)(TYPE)) >= 0 ? " " : "", \
((int)(TYPE)) >= 0 ? osmo_gad_type_name(TYPE) : "", ##args), \
}; \
} \
return RC; \
} while(0)
static int osmo_gad_enc_ell_point_unc_circle(struct gad_raw_ell_point_unc_circle *raw, const struct osmo_gad_ell_point_unc_circle *v)
{
if (v->lat < -90000000 || v->lat > 90000000)
return -EINVAL;
if (v->lon < -180000000 || v->lon > 180000000)
return -EINVAL;
*raw = (struct gad_raw_ell_point_unc_circle){
.h = { .type = GAD_TYPE_ELL_POINT_UNC_CIRCLE },
.unc = osmo_gad_enc_unc(v->unc),
};
osmo_store32be_ext(osmo_gad_enc_lat(v->lat), raw->lat, 3);
osmo_store32be_ext(osmo_gad_enc_lon(v->lon), raw->lon, 3);
return sizeof(raw);
}
static int osmo_gad_dec_ell_point_unc_circle(struct osmo_gad_ell_point_unc_circle *v,
struct osmo_gad_err **err, void *err_ctx,
const struct gad_raw_ell_point_unc_circle *raw)
{
/* Load 24bit big endian */
v->lat = osmo_gad_dec_lat(osmo_load32be_ext_2(raw->lat, 3));
v->lon = osmo_gad_dec_lon(osmo_load32be_ext_2(raw->lon, 3));
if (raw->spare2)
DEC_ERR(-EINVAL, raw->h.type, "Bit 8 of Uncertainty code should be zero");
v->unc = osmo_gad_dec_unc(raw->unc);
return 0;
}
static int osmo_gad_raw_len(const union gad_raw *gad_raw)
{
switch (gad_raw->h.type) {
case GAD_TYPE_ELL_POINT:
return sizeof(gad_raw->ell_point);
case GAD_TYPE_ELL_POINT_UNC_CIRCLE:
return sizeof(gad_raw->ell_point_unc_circle);
case GAD_TYPE_ELL_POINT_UNC_ELLIPSE:
return sizeof(gad_raw->ell_point_unc_ellipse);
case GAD_TYPE_POLYGON:
if (gad_raw->polygon.h.num_points < 3)
return -EINVAL;
return sizeof(gad_raw->polygon.h)
+ gad_raw->polygon.h.num_points * sizeof(gad_raw->polygon.point[0]);
case GAD_TYPE_ELL_POINT_ALT:
return sizeof(gad_raw->ell_point_alt);
case GAD_TYPE_ELL_POINT_ALT_UNC_ELL:
return sizeof(gad_raw->ell_point_alt_unc_ell);
case GAD_TYPE_ELL_ARC:
return sizeof(gad_raw->ell_arc);
case GAD_TYPE_HA_ELL_POINT_UNC_ELLIPSE:
return sizeof(gad_raw->ha_ell_point_unc_ell);
case GAD_TYPE_HA_ELL_POINT_ALT_UNC_ELL:
return sizeof(gad_raw->ha_ell_point_alt_unc_ell);
default:
return -ENOTSUP;
}
}
/*! Append a GAD PDU to the msgb.
* Write the correct number of bytes depending on the GAD type and possibly on variable length attributes.
* \param[out] msg Append to this msgb.
* \param[in] gad_raw GAD data to write.
* \returns number of bytes appended to msgb, or negative on failure.
*/
int osmo_gad_raw_write(struct msgb *msg, const union gad_raw *gad_raw)
{
int len;
uint8_t *dst;
len = osmo_gad_raw_len(gad_raw);
if (len < 0)
return len;
dst = msgb_put(msg, len);
memcpy(dst, (void*)gad_raw, len);
return len;
}
/*! Read a GAD PDU and validate structure.
* Memcpy from data to gad_raw struct, and validate correct length depending on the GAD type and possibly on variable
* length attributes.
* \param[out] gad_raw Copy GAD PDU here.
* \param[out] err Returned pointer to error info, dynamically allocated; NULL to not return any.
* \param[in] err_ctx Talloc context to allocate err from, if required.
* \param[in] data Encoded GAD bytes buffer.
* \param[in] len Length of data in bytes.
* \returns 0 on success, negative on error. If returning negative and err was non-NULL, *err is guaranteed to point to
* an allocated struct osmo_gad_err.
*/
int osmo_gad_raw_read(union gad_raw *gad_raw, struct osmo_gad_err **err, void *err_ctx, const uint8_t *data, uint8_t len)
{
int gad_len;
const union gad_raw *src;
if (err)
*err = NULL;
if (len < sizeof(src->h))
DEC_ERR(-EINVAL, -1, "GAD data too short for header (%u bytes)", len);
src = (void*)data;
gad_len = osmo_gad_raw_len(src);
if (gad_len < 0)
DEC_ERR(-EINVAL, src->h.type, "GAD data invalid (rc=%d)", gad_len);
if (gad_len != len)
DEC_ERR(-EINVAL, src->h.type, "GAD data with unexpected length: expected %d bytes, got %u",
gad_len, len);
memcpy((void*)gad_raw, data, gad_len);
return 0;
}
/*! Write GAD values with consistent units to raw GAD PDU representation.
* \param[out] gad_raw Write to this buffer.
* \param[in] gad GAD values to encode.
* \returns number of bytes written, or negative on failure.
*/
int osmo_gad_enc(union gad_raw *gad_raw, const struct osmo_gad *gad)
{
switch (gad->type) {
case GAD_TYPE_ELL_POINT_UNC_CIRCLE:
return osmo_gad_enc_ell_point_unc_circle(&gad_raw->ell_point_unc_circle, &gad->ell_point_unc_circle);
default:
return -ENOTSUP;
}
}
/*! Decode GAD raw PDU to values with consistent units.
* \param[out] gad Decoded GAD values are written here.
* \param[out] err Returned pointer to error info, dynamically allocated; NULL to not return any.
* \param[in] err_ctx Talloc context to allocate err from, if required.
* \param[in] raw Raw GAD data in network-byte-order.
* \returns 0 on success, negative on error. If returning negative and err was non-NULL, *err is guaranteed to point to
* an allocated struct osmo_gad_err.
*/
int osmo_gad_dec(struct osmo_gad *gad, struct osmo_gad_err **err, void *err_ctx, const union gad_raw *raw)
{
*gad = (struct osmo_gad){
.type = raw->h.type,
};
switch (raw->h.type) {
case GAD_TYPE_ELL_POINT_UNC_CIRCLE:
return osmo_gad_dec_ell_point_unc_circle(&gad->ell_point_unc_circle, err, err_ctx,
&raw->ell_point_unc_circle);
default:
DEC_ERR(-ENOTSUP, raw->h.type, "unsupported GAD type");
}
}
/*! Return a human readable representation of a raw GAD PDU.
* Convert to GAD values and feed the result to osmo_gad_to_str_buf().
* \param[out] buf Buffer to write string to.
* \param[in] buflen sizeof(buf).
* \param[in] gad Location data.
* \returns number of chars that would be written, like snprintf().
*/
int osmo_gad_raw_to_str_buf(char *buf, size_t buflen, const union gad_raw *raw)
{
struct osmo_gad gad;
if (osmo_gad_dec(&gad, NULL, NULL, raw)) {
struct osmo_strbuf sb = { .buf = buf, .len = buflen };
OSMO_STRBUF_PRINTF(sb, "invalid");
return sb.chars_needed;
}
return osmo_gad_to_str_buf(buf, buflen, &gad);
}
/*! Return a human readable representation of a raw GAD PDU.
* Convert to GAD values and feed the result to osmo_gad_to_str_buf().
* \param[in] ctx Talloc ctx to allocate string buffer from.
* \param[in] raw GAD data in network-byte-order.
* \returns resulting string, dynamically allocated.
*/
char *osmo_gad_raw_to_str_c(void *ctx, const union gad_raw *raw)
{
OSMO_NAME_C_IMPL(ctx, 128, "ERROR", osmo_gad_raw_to_str_buf, raw)
}
/*! Return a human readable representation of GAD (location estimate) values.
* \param[out] buf Buffer to write string to.
* \param[in] buflen sizeof(buf).
* \param[in] gad Location data.
* \returns number of chars that would be written, like snprintf().
*/
int osmo_gad_to_str_buf(char *buf, size_t buflen, const struct osmo_gad *gad)
{
struct osmo_strbuf sb = { .buf = buf, .len = buflen };
if (!gad) {
OSMO_STRBUF_PRINTF(sb, "null");
return sb.chars_needed;
}
OSMO_STRBUF_PRINTF(sb, "%s{", osmo_gad_type_name(gad->type));
switch (gad->type) {
case GAD_TYPE_ELL_POINT:
OSMO_STRBUF_PRINTF(sb, "lat=");
OSMO_STRBUF_APPEND(sb, osmo_int_to_float_str_buf, gad->ell_point.lat, 6);
OSMO_STRBUF_PRINTF(sb, ",lon=");
OSMO_STRBUF_APPEND(sb, osmo_int_to_float_str_buf, gad->ell_point.lon, 6);
break;
case GAD_TYPE_ELL_POINT_UNC_CIRCLE:
OSMO_STRBUF_PRINTF(sb, "lat=");
OSMO_STRBUF_APPEND(sb, osmo_int_to_float_str_buf, gad->ell_point_unc_circle.lat, 6);
OSMO_STRBUF_PRINTF(sb, ",lon=");
OSMO_STRBUF_APPEND(sb, osmo_int_to_float_str_buf, gad->ell_point_unc_circle.lon, 6);
OSMO_STRBUF_PRINTF(sb, ",unc=");
OSMO_STRBUF_APPEND(sb, osmo_int_to_float_str_buf, gad->ell_point_unc_circle.unc, 3);
OSMO_STRBUF_PRINTF(sb, "m");
break;
default:
OSMO_STRBUF_PRINTF(sb, "to-str-not-implemented");
break;
}
OSMO_STRBUF_PRINTF(sb, "}");
return sb.chars_needed;
}
/*! Return a human readable representation of GAD (location estimate) values.
* \param[in] ctx Talloc ctx to allocate string buffer from.
* \param[in] val Value to convert to float.
* \returns resulting string, dynamically allocated.
*/
char *osmo_gad_to_str_c(void *ctx, const struct osmo_gad *gad)
{
OSMO_NAME_C_IMPL(ctx, 128, "ERROR", osmo_gad_to_str_buf, gad)
}
/*! @} */
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