/* * (C) 2008 by Daniel Willmann * (C) 2009,2013 by Holger Hans Peter Freyther * (C) 2009-2010 by Harald Welte * (C) 2010-2012 by Nico Golde * * All Rights Reserved * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 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 General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. * */ /*! \mainpage libosmogsm Documentation * * \section sec_intro Introduction * This library is a collection of common code used in various * GSM related sub-projects inside the Osmocom family of projects. It * includes A5/1 and A5/2 ciphers, COMP128v1, a LAPDm implementation, * a GSM TLV parser, SMS utility routines as well as * protocol definitions for a series of protocols: * * Um L2 (04.06) * * Um L3 (04.08) * * A-bis RSL (08.58) * * A-bis OML (08.59, 12.21) * * A (08.08) * \n\n * Please note that C language projects inside Osmocom are typically * single-threaded event-loop state machine designs. As such, * routines in libosmogsm are not thread-safe. If you must use them in * a multi-threaded context, you have to add your own locking. * * \section sec_copyright Copyright and License * Copyright © 2008-2011 - Harald Welte, Holger Freyther and contributors\n * All rights reserved. \n\n * The source code of libosmogsm is licensed under the terms of the GNU * General Public License as published by the Free Software Foundation; * either version 2 of the License, or (at your option) any later * version.\n * See or COPYING included in the source * code package istelf.\n * The information detailed here is provided AS IS with NO WARRANTY OF * ANY KIND, INCLUDING THE WARRANTY OF DESIGN, MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE. * \n\n * * \section sec_contact Contact and Support * Community-based support is available at the OpenBSC mailing list * \n * Commercial support options available upon request from * */ //#include #include #include #include #include #include #include #include #include #include #include #include #include #include "../../config.h" /* ETSI GSM 03.38 6.2.1 and 6.2.1.1 default alphabet * Greek symbols at hex positions 0x10 and 0x12-0x1a * left out as they can't be handled with a char and * since most phones don't display or write these * characters this would only needlessly make the code * more complex. * * Note that this table contains the latin1->7bit mapping _and_ has * been merged with the reverse mapping (7bit->latin1) for the * extended characters at offset 0x7f. */ static unsigned char gsm_7bit_alphabet[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0a, 0xff, 0xff, 0x0d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x20, 0x21, 0x22, 0x23, 0x02, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x00, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x3c, 0x2f, 0x3e, 0x14, 0x11, 0xff, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x28, 0x40, 0x29, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0c, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5e, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x40, 0xff, 0x01, 0xff, 0x03, 0xff, 0x7b, 0x7d, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5c, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5b, 0x7e, 0x5d, 0xff, 0x7c, 0xff, 0xff, 0xff, 0xff, 0x5b, 0x0e, 0x1c, 0x09, 0xff, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5d, 0xff, 0xff, 0xff, 0xff, 0x5c, 0xff, 0x0b, 0xff, 0xff, 0xff, 0x5e, 0xff, 0xff, 0x1e, 0x7f, 0xff, 0xff, 0xff, 0x7b, 0x0f, 0x1d, 0xff, 0x04, 0x05, 0xff, 0xff, 0x07, 0xff, 0xff, 0xff, 0xff, 0x7d, 0x08, 0xff, 0xff, 0xff, 0x7c, 0xff, 0x0c, 0x06, 0xff, 0xff, 0x7e, 0xff, 0xff }; /* GSM 03.38 6.2.1 Character lookup for decoding */ static int gsm_septet_lookup(uint8_t ch) { int i = 0; for (; i < sizeof(gsm_7bit_alphabet); i++) { if (gsm_7bit_alphabet[i] == ch) return i; } return -1; } /* Compute the number of octets from the number of septets, for instance: 47 septets needs 41,125 = 42 octets */ uint8_t gsm_get_octet_len(const uint8_t sept_len){ int octet_len = (sept_len * 7) / 8; if ((sept_len * 7) % 8 != 0) octet_len++; return octet_len; } /* GSM 03.38 6.2.1 Character unpacking */ int gsm_7bit_decode_n_hdr(char *text, size_t n, const uint8_t *user_data, uint8_t septet_l, uint8_t ud_hdr_ind) { unsigned shift = 0; uint8_t c7, c8, next_is_ext = 0, lu, ru; const uint8_t maxlen = gsm_get_octet_len(septet_l); const char *text_buf_begin = text; const char *text_buf_end = text + n; OSMO_ASSERT (n > 0); /* skip the user data header */ if (ud_hdr_ind) { /* get user data header length + 1 (for the 'user data header length'-field) */ shift = ((user_data[0] + 1) * 8) / 7; if ((((user_data[0] + 1) * 8) % 7) != 0) shift++; septet_l = septet_l - shift; } unsigned i, l, r; for (i = 0; i < septet_l && text != text_buf_end - 1; i++) { l = ((i + shift) * 7 + 7) >> 3; r = ((i + shift) * 7) >> 3; /* the left side index is always >= right side index sometimes it even gets beyond array boundary check for that explicitly and force 0 instead */ if (l >= maxlen) lu = 0; else lu = user_data[l] << (7 - (((i + shift) * 7 + 7) & 7)); ru = user_data[r] >> (((i + shift) * 7) & 7); c7 = (lu | ru) & 0x7f; if (next_is_ext) { /* this is an extension character */ next_is_ext = 0; c8 = gsm_7bit_alphabet[0x7f + c7]; } else if (c7 == 0x1b && i + 1 < septet_l) { next_is_ext = 1; continue; } else { c8 = gsm_septet_lookup(c7); } *(text++) = c8; } *text = '\0'; return text - text_buf_begin; } int gsm_7bit_decode_n(char *text, size_t n, const uint8_t *user_data, uint8_t septet_l) { return gsm_7bit_decode_n_hdr(text, n, user_data, septet_l, 0); } int gsm_7bit_decode_n_ussd(char *text, size_t n, const uint8_t *user_data, uint8_t length) { int nchars; nchars = gsm_7bit_decode_n_hdr(text, n, user_data, length, 0); /* remove last , if it fits up to the end of last octet */ if (nchars && (user_data[gsm_get_octet_len(length) - 1] >> 1) == '\r') text[--nchars] = '\0'; return nchars; } /* GSM 03.38 6.2.1 Prepare character packing */ int gsm_septet_encode(uint8_t *result, const char *data) { int i, y = 0; uint8_t ch; for (i = 0; i < strlen(data); i++) { ch = data[i]; switch(ch){ /* fall-through for extension characters */ case 0x0c: case 0x5e: case 0x7b: case 0x7d: case 0x5c: case 0x5b: case 0x7e: case 0x5d: case 0x7c: result[y++] = 0x1b; default: result[y] = gsm_7bit_alphabet[ch]; break; } y++; } return y; } /* 7bit to octet packing */ int gsm_septets2octets(uint8_t *result, const uint8_t *rdata, uint8_t septet_len, uint8_t padding) { int i = 0, z = 0; uint8_t cb, nb; int shift = 0; uint8_t *data = calloc(septet_len + 1, sizeof(uint8_t)); if (padding) { shift = 7 - padding; /* the first zero is needed for padding */ memcpy(data + 1, rdata, septet_len); septet_len++; } else memcpy(data, rdata, septet_len); for (i = 0; i < septet_len; i++) { if (shift == 7) { /* * special end case with the. This is necessary if the * last septet fits into the previous octet. E.g. 48 * non-extension characters: * ....ag ( a = 1100001, g = 1100111) * result[40] = 100001 XX, result[41] = 1100111 1 */ if (i + 1 < septet_len) { shift = 0; continue; } else if (i + 1 == septet_len) break; } cb = (data[i] & 0x7f) >> shift; if (i + 1 < septet_len) { nb = (data[i + 1] & 0x7f) << (7 - shift); cb = cb | nb; } result[z++] = cb; shift++; } free(data); return z; } /* GSM 03.38 6.2.1 Character packing */ int gsm_7bit_encode_n(uint8_t *result, size_t n, const char *data, int *octets) { int y = 0; int o; size_t max_septets = n * 8 / 7; /* prepare for the worst case, every character expanding to two bytes */ uint8_t *rdata = calloc(strlen(data) * 2, sizeof(uint8_t)); y = gsm_septet_encode(rdata, data); if (y > max_septets) { /* * Limit the number of septets to avoid the generation * of more than n octets. */ y = max_septets; } o = gsm_septets2octets(result, rdata, y, 0); if (octets) *octets = o; free(rdata); /* * We don't care about the number of octets, because they are not * unique. E.g.: * 1.) 46 non-extension characters + 1 extension character * => (46 * 7 bit + (1 * (2 * 7 bit))) / 8 bit = 42 octets * 2.) 47 non-extension characters * => (47 * 7 bit) / 8 bit = 41,125 = 42 octets * 3.) 48 non-extension characters * => (48 * 7 bit) / 8 bit = 42 octects */ return y; } int gsm_7bit_encode_n_ussd(uint8_t *result, size_t n, const char *data, int *octets) { int y; y = gsm_7bit_encode_n(result, n, data, octets); /* if last octet contains only one bit, add */ if (((y * 7) & 7) == 1) result[(*octets) - 1] |= ('\r' << 1); /* if last character is and completely fills last octet, add * another . */ if (y && ((y * 7) & 7) == 0 && (result[(*octets) - 1] >> 1) == '\r' && *octets < n - 1) { result[(*octets)++] = '\r'; y++; } return y; } /*! \brief Build the RSL uplink measurement IE (3GPP TS 08.58 § 9.3.25) * \param[in] mru Unidirectional measurement report structure * \param[in] dtxd_used Indicates if DTXd was used during measurement report * period * \param[out] buf Pre-allocated bufer for storing IE * \returns Number of bytes filled in buf */ size_t gsm0858_rsl_ul_meas_enc(struct gsm_meas_rep_unidir *mru, bool dtxd_used, uint8_t *buf) { buf[0] = dtxd_used ? (1 << 6) : 0; buf[0] |= (mru->full.rx_lev & 0x3f); buf[1] = (mru->sub.rx_lev & 0x3f); buf[2] = ((mru->full.rx_qual & 7) << 3) | (mru->sub.rx_qual & 7); return 3; } /* convert power class to dBm according to GSM TS 05.05 */ unsigned int ms_class_gmsk_dbm(enum gsm_band band, int class) { switch (band) { case GSM_BAND_450: case GSM_BAND_480: case GSM_BAND_750: case GSM_BAND_900: case GSM_BAND_810: case GSM_BAND_850: if (class == 1) return 43; /* 20W */ if (class == 2) return 39; /* 8W */ if (class == 3) return 37; /* 5W */ if (class == 4) return 33; /* 2W */ if (class == 5) return 29; /* 0.8W */ break; case GSM_BAND_1800: if (class == 1) return 30; /* 1W */ if (class == 2) return 24; /* 0.25W */ if (class == 3) return 36; /* 4W */ break; case GSM_BAND_1900: if (class == 1) return 30; /* 1W */ if (class == 2) return 24; /* 0.25W */ if (class == 3) return 33; /* 2W */ break; } return -EINVAL; } /* determine power control level for given dBm value, as indicated * by the tables in chapter 4.1.1 of GSM TS 05.05 */ int ms_pwr_ctl_lvl(enum gsm_band band, unsigned int dbm) { switch (band) { case GSM_BAND_450: case GSM_BAND_480: case GSM_BAND_750: case GSM_BAND_900: case GSM_BAND_810: case GSM_BAND_850: if (dbm >= 39) return 0; else if (dbm < 5) return 19; else { /* we are guaranteed to have (5 <= dbm < 39) */ return 2 + ((39 - dbm) / 2); } break; case GSM_BAND_1800: if (dbm >= 36) return 29; else if (dbm >= 34) return 30; else if (dbm >= 32) return 31; else if (dbm == 31) return 0; else { /* we are guaranteed to have (0 <= dbm < 31) */ return (30 - dbm) / 2; } break; case GSM_BAND_1900: if (dbm >= 33) return 30; else if (dbm >= 32) return 31; else if (dbm == 31) return 0; else { /* we are guaranteed to have (0 <= dbm < 31) */ return (30 - dbm) / 2; } break; } return -EINVAL; } int ms_pwr_dbm(enum gsm_band band, uint8_t lvl) { lvl &= 0x1f; switch (band) { case GSM_BAND_450: case GSM_BAND_480: case GSM_BAND_750: case GSM_BAND_900: case GSM_BAND_810: case GSM_BAND_850: if (lvl < 2) return 39; else if (lvl < 20) return 39 - ((lvl - 2) * 2) ; else return 5; break; case GSM_BAND_1800: if (lvl < 16) return 30 - (lvl * 2); else if (lvl < 29) return 0; else return 36 - ((lvl - 29) * 2); break; case GSM_BAND_1900: if (lvl < 16) return 30 - (lvl * 2); else if (lvl < 30) return -EINVAL; else return 33 - (lvl - 30); break; } return -EINVAL; } /* According to TS 05.08 Chapter 8.1.4 */ int rxlev2dbm(uint8_t rxlev) { if (rxlev > 63) rxlev = 63; return -110 + rxlev; } /* According to TS 05.08 Chapter 8.1.4 */ uint8_t dbm2rxlev(int dbm) { int rxlev = dbm + 110; if (rxlev > 63) rxlev = 63; else if (rxlev < 0) rxlev = 0; return rxlev; } const char *gsm_band_name(enum gsm_band band) { switch (band) { case GSM_BAND_450: return "GSM450"; case GSM_BAND_480: return "GSM480"; case GSM_BAND_750: return "GSM750"; case GSM_BAND_810: return "GSM810"; case GSM_BAND_850: return "GSM850"; case GSM_BAND_900: return "GSM900"; case GSM_BAND_1800: return "DCS1800"; case GSM_BAND_1900: return "PCS1900"; } return "invalid"; } enum gsm_band gsm_band_parse(const char* mhz) { while (*mhz && !isdigit(*mhz)) mhz++; if (*mhz == '\0') return -EINVAL; switch (strtol(mhz, NULL, 10)) { case 450: return GSM_BAND_450; case 480: return GSM_BAND_480; case 750: return GSM_BAND_750; case 810: return GSM_BAND_810; case 850: return GSM_BAND_850; case 900: return GSM_BAND_900; case 1800: return GSM_BAND_1800; case 1900: return GSM_BAND_1900; default: return -EINVAL; } } enum gsm_band gsm_arfcn2band(uint16_t arfcn) { int is_pcs = arfcn & ARFCN_PCS; arfcn &= ~ARFCN_FLAG_MASK; if (is_pcs) return GSM_BAND_1900; else if (arfcn <= 124) return GSM_BAND_900; else if (arfcn >= 955 && arfcn <= 1023) return GSM_BAND_900; else if (arfcn >= 128 && arfcn <= 251) return GSM_BAND_850; else if (arfcn >= 512 && arfcn <= 885) return GSM_BAND_1800; else if (arfcn >= 259 && arfcn <= 293) return GSM_BAND_450; else if (arfcn >= 306 && arfcn <= 340) return GSM_BAND_480; else if (arfcn >= 350 && arfcn <= 425) return GSM_BAND_810; else if (arfcn >= 438 && arfcn <= 511) return GSM_BAND_750; else return GSM_BAND_1800; } struct gsm_freq_range { uint16_t arfcn_first; uint16_t arfcn_last; uint16_t freq_ul_first; uint16_t freq_dl_offset; uint16_t flags; }; static struct gsm_freq_range gsm_ranges[] = { { 512, 810, 18502, 800, ARFCN_PCS }, /* PCS 1900 */ { 0, 124, 8900, 450, 0 }, /* P-GSM + E-GSM ARFCN 0 */ { 955, 1023, 8762, 450, 0 }, /* E-GSM + R-GSM */ { 128, 251, 8242, 450, 0 }, /* GSM 850 */ { 512, 885, 17102, 950, 0 }, /* DCS 1800 */ { 259, 293, 4506, 100, 0 }, /* GSM 450 */ { 306, 340, 4790, 100, 0 }, /* GSM 480 */ { 350, 425, 8060, 450, 0 }, /* GSM 810 */ { 438, 511, 7472, 300, 0 }, /* GSM 750 */ { /* Guard */ } }; /* Convert an ARFCN to the frequency in MHz * 10 */ uint16_t gsm_arfcn2freq10(uint16_t arfcn, int uplink) { struct gsm_freq_range *r; uint16_t flags = arfcn & ARFCN_FLAG_MASK; uint16_t freq10_ul = 0xffff; uint16_t freq10_dl = 0xffff; arfcn &= ~ARFCN_FLAG_MASK; for (r=gsm_ranges; r->freq_ul_first>0; r++) { if ((flags == r->flags) && (arfcn >= r->arfcn_first) && (arfcn <= r->arfcn_last)) { freq10_ul = r->freq_ul_first + 2 * (arfcn - r->arfcn_first); freq10_dl = freq10_ul + r->freq_dl_offset; break; } } return uplink ? freq10_ul : freq10_dl; } /* Convert a Frequency in MHz * 10 to ARFCN */ uint16_t gsm_freq102arfcn(uint16_t freq10, int uplink) { struct gsm_freq_range *r; uint16_t freq10_lo, freq10_hi; uint16_t arfcn = 0xffff; for (r=gsm_ranges; r->freq_ul_first>0; r++) { /* Generate frequency limits */ freq10_lo = r->freq_ul_first; freq10_hi = freq10_lo + 2 * (r->arfcn_last - r->arfcn_first); if (!uplink) { freq10_lo += r->freq_dl_offset; freq10_hi += r->freq_dl_offset; } /* Check if this fits */ if (freq10 >= freq10_lo && freq10 <= freq10_hi) { arfcn = r->arfcn_first + ((freq10 - freq10_lo) >> 1); arfcn |= r->flags; break; } } if (uplink) arfcn |= ARFCN_UPLINK; return arfcn; } void gsm_fn2gsmtime(struct gsm_time *time, uint32_t fn) { time->fn = fn; time->t1 = time->fn / (26*51); time->t2 = time->fn % 26; time->t3 = time->fn % 51; time->tc = (time->fn / 51) % 8; } uint32_t gsm_gsmtime2fn(struct gsm_time *time) { /* TS 05.02 Chapter 4.3.3 TDMA frame number */ return (51 * ((time->t3 - time->t2 + 26) % 26) + time->t3 + (26 * 51 * time->t1)); } /*! \brief append range1024 encoded data to bit vector */ void bitvec_add_range1024(struct bitvec *bv, const struct gsm48_range_1024 *r) { bitvec_set_uint(bv, r->w1_hi, 2); bitvec_set_uint(bv, r->w1_lo, 8); bitvec_set_uint(bv, r->w2_hi, 8); bitvec_set_uint(bv, r->w2_lo, 1); bitvec_set_uint(bv, r->w3_hi, 7); bitvec_set_uint(bv, r->w3_lo, 2); bitvec_set_uint(bv, r->w4_hi, 6); bitvec_set_uint(bv, r->w4_lo, 2); bitvec_set_uint(bv, r->w5_hi, 6); bitvec_set_uint(bv, r->w5_lo, 2); bitvec_set_uint(bv, r->w6_hi, 6); bitvec_set_uint(bv, r->w6_lo, 2); bitvec_set_uint(bv, r->w7_hi, 6); bitvec_set_uint(bv, r->w7_lo, 2); bitvec_set_uint(bv, r->w8_hi, 6); bitvec_set_uint(bv, r->w8_lo, 1); bitvec_set_uint(bv, r->w9, 7); bitvec_set_uint(bv, r->w10, 7); bitvec_set_uint(bv, r->w11_hi, 1); bitvec_set_uint(bv, r->w11_lo, 6); bitvec_set_uint(bv, r->w12_hi, 2); bitvec_set_uint(bv, r->w12_lo, 5); bitvec_set_uint(bv, r->w13_hi, 3); bitvec_set_uint(bv, r->w13_lo, 4); bitvec_set_uint(bv, r->w14_hi, 4); bitvec_set_uint(bv, r->w14_lo, 3); bitvec_set_uint(bv, r->w15_hi, 5); bitvec_set_uint(bv, r->w15_lo, 2); bitvec_set_uint(bv, r->w16, 6); } /* TS 23.003 Chapter 2.6 */ int gprs_tlli_type(uint32_t tlli) { if ((tlli & 0xc0000000) == 0xc0000000) return TLLI_LOCAL; else if ((tlli & 0xc0000000) == 0x80000000) return TLLI_FOREIGN; else if ((tlli & 0xf8000000) == 0x78000000) return TLLI_RANDOM; else if ((tlli & 0xf8000000) == 0x70000000) return TLLI_AUXILIARY; else if ((tlli & 0xf0000000) == 0x00000000) return TLLI_G_RNTI; else if ((tlli & 0xf0000000) == 0x10000000) return TLLI_RAND_G_RNTI; return TLLI_RESERVED; } uint32_t gprs_tmsi2tlli(uint32_t p_tmsi, enum gprs_tlli_type type) { uint32_t tlli; switch (type) { case TLLI_LOCAL: tlli = p_tmsi | 0xc0000000; break; case TLLI_FOREIGN: tlli = (p_tmsi & 0x3fffffff) | 0x80000000; break; default: tlli = 0; break; } return tlli; } /* Wrappers for deprecated functions: */ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t septet_l) { gsm_7bit_decode_n(text, GSM_7BIT_LEGACY_MAX_BUFFER_SIZE, user_data, septet_l); /* Mimic the original behaviour. */ return septet_l; } int gsm_7bit_decode_ussd(char *text, const uint8_t *user_data, uint8_t length) { return gsm_7bit_decode_n_ussd(text, GSM_7BIT_LEGACY_MAX_BUFFER_SIZE, user_data, length); } int gsm_7bit_encode(uint8_t *result, const char *data) { int out; return gsm_7bit_encode_n(result, GSM_7BIT_LEGACY_MAX_BUFFER_SIZE, data, &out); } int gsm_7bit_encode_ussd(uint8_t *result, const char *data, int *octets) { return gsm_7bit_encode_n_ussd(result, GSM_7BIT_LEGACY_MAX_BUFFER_SIZE, data, octets); } int gsm_7bit_encode_oct(uint8_t *result, const char *data, int *octets) { return gsm_7bit_encode_n(result, GSM_7BIT_LEGACY_MAX_BUFFER_SIZE, data, octets); }