Harald Welte | c676c68 | 2017-12-24 20:38:20 +0100 | [diff] [blame] | 1 | |
| 2 | #include "Octetstring.hh" |
| 3 | #include "Error.hh" |
| 4 | #include "Logger.hh" |
| 5 | |
| 6 | #include "IuUP_Types.hh" |
| 7 | |
| 8 | #include <stdint.h> |
| 9 | |
| 10 | extern "C" { |
| 11 | |
| 12 | typedef uint8_t ubit_t; |
| 13 | typedef uint8_t pbit_t; |
| 14 | |
| 15 | static int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits) |
| 16 | { |
| 17 | unsigned int i; |
| 18 | ubit_t *cur = out; |
| 19 | ubit_t *limit = out + num_bits; |
| 20 | |
| 21 | for (i = 0; i < (num_bits/8)+1; i++) { |
| 22 | pbit_t byte = in[i]; |
| 23 | *cur++ = (byte >> 7) & 1; |
| 24 | if (cur >= limit) |
| 25 | break; |
| 26 | *cur++ = (byte >> 6) & 1; |
| 27 | if (cur >= limit) |
| 28 | break; |
| 29 | *cur++ = (byte >> 5) & 1; |
| 30 | if (cur >= limit) |
| 31 | break; |
| 32 | *cur++ = (byte >> 4) & 1; |
| 33 | if (cur >= limit) |
| 34 | break; |
| 35 | *cur++ = (byte >> 3) & 1; |
| 36 | if (cur >= limit) |
| 37 | break; |
| 38 | *cur++ = (byte >> 2) & 1; |
| 39 | if (cur >= limit) |
| 40 | break; |
| 41 | *cur++ = (byte >> 1) & 1; |
| 42 | if (cur >= limit) |
| 43 | break; |
| 44 | *cur++ = (byte >> 0) & 1; |
| 45 | if (cur >= limit) |
| 46 | break; |
| 47 | } |
| 48 | return cur - out; |
| 49 | } |
| 50 | |
| 51 | |
| 52 | struct osmo_crc8gen_code { |
| 53 | int bits; /*!< Actual number of bits of the CRC */ |
| 54 | uint8_t poly; /*!< Polynom (normal representation, MSB omitted */ |
| 55 | uint8_t init; /*!< Initialization value of the CRC state */ |
| 56 | uint8_t remainder; /*!< Remainder of the CRC (final XOR) */ |
| 57 | }; |
| 58 | |
| 59 | static uint8_t |
| 60 | osmo_crc8gen_compute_bits(const struct osmo_crc8gen_code *code, |
| 61 | const ubit_t *in, int len) |
| 62 | { |
| 63 | const uint8_t poly = code->poly; |
| 64 | uint8_t crc = code->init; |
| 65 | int i, n = code->bits-1; |
| 66 | |
| 67 | for (i=0; i<len; i++) { |
| 68 | uint8_t bit = in[i] & 1; |
| 69 | crc ^= (bit << n); |
| 70 | if (crc & ((uint8_t)1 << n)) { |
| 71 | crc <<= 1; |
| 72 | crc ^= poly; |
| 73 | } else { |
| 74 | crc <<= 1; |
| 75 | } |
| 76 | crc &= ((uint8_t)1 << code->bits) - 1; |
| 77 | } |
| 78 | |
| 79 | crc ^= code->remainder; |
| 80 | |
| 81 | return crc; |
| 82 | } |
| 83 | |
| 84 | struct osmo_crc16gen_code { |
| 85 | int bits; /*!< Actual number of bits of the CRC */ |
| 86 | uint16_t poly; /*!< Polynom (normal representation, MSB omitted */ |
| 87 | uint16_t init; /*!< Initialization value of the CRC state */ |
| 88 | uint16_t remainder; /*!< Remainder of the CRC (final XOR) */ |
| 89 | }; |
| 90 | |
| 91 | static uint16_t |
| 92 | osmo_crc16gen_compute_bits(const struct osmo_crc16gen_code *code, |
| 93 | const ubit_t *in, int len) |
| 94 | { |
| 95 | const uint16_t poly = code->poly; |
| 96 | uint16_t crc = code->init; |
| 97 | int i, n = code->bits-1; |
| 98 | |
| 99 | for (i=0; i<len; i++) { |
| 100 | uint16_t bit = in[i] & 1; |
| 101 | crc ^= (bit << n); |
| 102 | if (crc & ((uint16_t)1 << n)) { |
| 103 | crc <<= 1; |
| 104 | crc ^= poly; |
| 105 | } else { |
| 106 | crc <<= 1; |
| 107 | } |
| 108 | crc &= ((uint16_t)1 << code->bits) - 1; |
| 109 | } |
| 110 | |
| 111 | crc ^= code->remainder; |
| 112 | |
| 113 | return crc; |
| 114 | } |
| 115 | |
| 116 | } |
| 117 | |
| 118 | |
| 119 | static const struct osmo_crc8gen_code iuup_hdr_crc_code = { |
| 120 | .bits = 6, |
| 121 | .poly = 47, |
| 122 | .init = 0, |
| 123 | .remainder = 0, |
| 124 | }; |
| 125 | |
| 126 | static const struct osmo_crc16gen_code iuup_data_crc_code = { |
| 127 | .bits = 10, |
| 128 | .poly = 563, |
| 129 | .init = 0, |
| 130 | .remainder = 0, |
| 131 | }; |
| 132 | |
| 133 | static int iuup_get_payload_offset(const uint8_t *iuup_pdu) |
| 134 | { |
| 135 | uint8_t pdu_type = iuup_pdu[0] >> 4; |
| 136 | switch (pdu_type) { |
| 137 | case 0: |
| 138 | case 14: |
| 139 | return 4; |
| 140 | case 1: |
| 141 | return 3; |
| 142 | default: |
| 143 | return -1; |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | int osmo_iuup_compute_payload_crc(const uint8_t *iuup_pdu, unsigned int pdu_len) |
| 148 | { |
| 149 | ubit_t buf[1024*8]; |
| 150 | uint8_t pdu_type; |
| 151 | int offset, payload_len_bytes; |
| 152 | |
| 153 | if (pdu_len < 1) |
| 154 | return -1; |
| 155 | |
| 156 | pdu_type = iuup_pdu[0] >> 4; |
| 157 | |
| 158 | /* Type 1 has no CRC */ |
| 159 | if (pdu_type == 1) |
| 160 | return 0; |
| 161 | |
| 162 | offset = iuup_get_payload_offset(iuup_pdu); |
| 163 | if (offset < 0) |
| 164 | return offset; |
| 165 | |
| 166 | if (pdu_len < (unsigned int)offset) |
| 167 | return -1; |
| 168 | |
| 169 | payload_len_bytes = pdu_len - offset; |
| 170 | osmo_pbit2ubit(buf, iuup_pdu+offset, payload_len_bytes*8); |
| 171 | return osmo_crc16gen_compute_bits(&iuup_data_crc_code, buf, payload_len_bytes*8); |
| 172 | } |
| 173 | |
| 174 | int osmo_iuup_compute_header_crc(const uint8_t *iuup_pdu, unsigned int pdu_len) |
| 175 | { |
| 176 | ubit_t buf[2*8]; |
| 177 | |
| 178 | if (pdu_len < 2) |
| 179 | return -1; |
| 180 | |
| 181 | osmo_pbit2ubit(buf, iuup_pdu, 2*8); |
| 182 | return osmo_crc8gen_compute_bits(&iuup_hdr_crc_code, buf, 2*8); |
| 183 | } |
| 184 | /* IuUP CRC Implementation */ |
| 185 | |
| 186 | /* (C) 2017 by Harald Welte <laforge@gnumonks.org> |
| 187 | * |
| 188 | * All Rights Reserved |
| 189 | * |
| 190 | * This program is free software; you can redistribute it and/or modify |
| 191 | * it under the terms of the GNU General Public License as published by |
| 192 | * the Free Software Foundation; either version 2 of the License, or |
| 193 | * (at your option) any later version. |
| 194 | * |
| 195 | * This program is distributed in the hope that it will be useful, |
| 196 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 197 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
Harald Welte | 4895d7a | 2020-03-01 20:26:26 +0100 | [diff] [blame] | 198 | * GNU General Public License for more details. |
Harald Welte | c676c68 | 2017-12-24 20:38:20 +0100 | [diff] [blame] | 199 | * |
Harald Welte | 4895d7a | 2020-03-01 20:26:26 +0100 | [diff] [blame] | 200 | * You should have received a copy of the GNU General Public License |
Harald Welte | c676c68 | 2017-12-24 20:38:20 +0100 | [diff] [blame] | 201 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 202 | * |
| 203 | */ |
| 204 | |
| 205 | namespace IuUP__Types { |
| 206 | |
| 207 | |
| 208 | INTEGER f__IuUP__compute__crc__payload(OCTETSTRING const &in) |
| 209 | { |
| 210 | int crc_calc; |
| 211 | const unsigned char *data = (const unsigned char *)in; |
| 212 | int len = in.lengthof(); |
| 213 | |
| 214 | crc_calc = osmo_iuup_compute_payload_crc(data, len); |
| 215 | |
| 216 | return INTEGER(crc_calc); |
| 217 | } |
| 218 | |
| 219 | INTEGER f__IuUP__compute__crc__header(OCTETSTRING const &in) |
| 220 | { |
| 221 | int crc_calc; |
| 222 | const unsigned char *data = (const unsigned char *)in; |
| 223 | int len = in.lengthof(); |
| 224 | |
| 225 | crc_calc = osmo_iuup_compute_header_crc(data, len); |
| 226 | |
| 227 | return INTEGER(crc_calc); |
| 228 | } |
| 229 | |
| 230 | OCTETSTRING f__enc__IuUP__PDU(const IuUP__PDU& pdu) |
| 231 | { |
| 232 | TTCN_Buffer buf; |
| 233 | int crc_hdr, crc_payload; |
| 234 | uint8_t in[2]; |
| 235 | pdu.encode(IuUP__PDU_descr_, buf, TTCN_EncDec::CT_RAW); |
| 236 | OCTETSTRING ret_val(buf.get_len(), buf.get_data()); |
| 237 | |
| 238 | crc_hdr = osmo_iuup_compute_header_crc(buf.get_data(), buf.get_len()); |
| 239 | crc_payload = osmo_iuup_compute_payload_crc(buf.get_data(), buf.get_len()); |
| 240 | in[0] = (crc_hdr & 0x3f) << 2; |
| 241 | in[0] |= (crc_payload & 0x3ff) >> 8; |
| 242 | in[1] = crc_payload & 0xff; |
| 243 | OCTETSTRING CHECKSUM(2, in); |
| 244 | |
| 245 | ret_val = substr(ret_val, 0, 2) + CHECKSUM + substr(ret_val, 4, ret_val.lengthof()-4); |
| 246 | |
| 247 | return ret_val; |
| 248 | } |
| 249 | |
| 250 | } |