Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 1 | /* Copyright (c) 2008-2009, 2012-2014, The Linux Foundation. |
| 2 | * All rights reserved. |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 and |
| 6 | * only version 2 as published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | * GNU General Public License for more details. |
| 12 | * |
| 13 | */ |
| 14 | |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 15 | #include <stdint.h> |
| 16 | #include <stdlib.h> |
| 17 | #include <stdio.h> |
| 18 | #include <string.h> |
| 19 | #include <errno.h> |
| 20 | #include <sys/types.h> |
| 21 | |
| 22 | #include <osmocom/core/crc16.h> |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 23 | #include "diagchar_hdlc.h" |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 24 | |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 25 | #define CONTROL_CHAR 0x7E |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 26 | |
| 27 | #define CRC_16_L_SEED 0xFFFF |
| 28 | |
| 29 | #define CRC_16_L_STEP(xx_crc, xx_c) \ |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 30 | osmo_crc16_ccitt_byte(xx_crc, xx_c) |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 31 | |
| 32 | void diag_hdlc_encode(struct diag_send_desc_type *src_desc, |
| 33 | struct diag_hdlc_dest_type *enc) |
| 34 | { |
| 35 | uint8_t *dest; |
| 36 | uint8_t *dest_last; |
| 37 | const uint8_t *src; |
| 38 | const uint8_t *src_last; |
| 39 | uint16_t crc; |
| 40 | unsigned char src_byte = 0; |
| 41 | enum diag_send_state_enum_type state; |
| 42 | unsigned int used = 0; |
| 43 | |
| 44 | if (src_desc && enc) { |
| 45 | |
| 46 | /* Copy parts to local variables. */ |
| 47 | src = src_desc->pkt; |
| 48 | src_last = src_desc->last; |
| 49 | state = src_desc->state; |
| 50 | dest = enc->dest; |
| 51 | dest_last = enc->dest_last; |
| 52 | |
| 53 | if (state == DIAG_STATE_START) { |
| 54 | crc = CRC_16_L_SEED; |
| 55 | state++; |
| 56 | } else { |
| 57 | /* Get a local copy of the CRC */ |
| 58 | crc = enc->crc; |
| 59 | } |
| 60 | |
| 61 | /* dest or dest_last may be NULL to trigger a |
| 62 | state transition only */ |
| 63 | if (dest && dest_last) { |
| 64 | /* This condition needs to include the possibility |
| 65 | of 2 dest bytes for an escaped byte */ |
| 66 | while (src <= src_last && dest <= dest_last) { |
| 67 | |
| 68 | src_byte = *src++; |
| 69 | |
| 70 | if ((src_byte == CONTROL_CHAR) || |
| 71 | (src_byte == ESC_CHAR)) { |
| 72 | |
| 73 | /* If the escape character is not the |
| 74 | last byte */ |
| 75 | if (dest != dest_last) { |
| 76 | crc = CRC_16_L_STEP(crc, |
| 77 | src_byte); |
| 78 | |
| 79 | *dest++ = ESC_CHAR; |
| 80 | used++; |
| 81 | |
| 82 | *dest++ = src_byte |
| 83 | ^ ESC_MASK; |
| 84 | used++; |
| 85 | } else { |
| 86 | |
| 87 | src--; |
| 88 | break; |
| 89 | } |
| 90 | |
| 91 | } else { |
| 92 | crc = CRC_16_L_STEP(crc, src_byte); |
| 93 | *dest++ = src_byte; |
| 94 | used++; |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | if (src > src_last) { |
| 99 | |
| 100 | if (state == DIAG_STATE_BUSY) { |
| 101 | if (src_desc->terminate) { |
| 102 | crc = ~crc; |
| 103 | state++; |
| 104 | } else { |
| 105 | /* Done with fragment */ |
| 106 | state = DIAG_STATE_COMPLETE; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | while (dest <= dest_last && |
| 111 | state >= DIAG_STATE_CRC1 && |
| 112 | state < DIAG_STATE_TERM) { |
| 113 | /* Encode a byte of the CRC next */ |
| 114 | src_byte = crc & 0xFF; |
| 115 | |
| 116 | if ((src_byte == CONTROL_CHAR) |
| 117 | || (src_byte == ESC_CHAR)) { |
| 118 | |
| 119 | if (dest != dest_last) { |
| 120 | |
| 121 | *dest++ = ESC_CHAR; |
| 122 | used++; |
| 123 | *dest++ = src_byte ^ |
| 124 | ESC_MASK; |
| 125 | used++; |
| 126 | |
| 127 | crc >>= 8; |
| 128 | } else { |
| 129 | |
| 130 | break; |
| 131 | } |
| 132 | } else { |
| 133 | |
| 134 | crc >>= 8; |
| 135 | *dest++ = src_byte; |
| 136 | used++; |
| 137 | } |
| 138 | |
| 139 | state++; |
| 140 | } |
| 141 | |
| 142 | if (state == DIAG_STATE_TERM) { |
| 143 | if (dest_last >= dest) { |
| 144 | *dest++ = CONTROL_CHAR; |
| 145 | used++; |
| 146 | state++; /* Complete */ |
| 147 | } |
| 148 | } |
| 149 | } |
| 150 | } |
| 151 | /* Copy local variables back into the encode structure. */ |
| 152 | |
| 153 | enc->dest = dest; |
| 154 | enc->dest_last = dest_last; |
| 155 | enc->crc = crc; |
| 156 | src_desc->pkt = src; |
| 157 | src_desc->last = src_last; |
| 158 | src_desc->state = state; |
| 159 | } |
| 160 | |
| 161 | return; |
| 162 | } |
| 163 | |
| 164 | |
| 165 | int diag_hdlc_decode(struct diag_hdlc_decode_type *hdlc) |
| 166 | { |
| 167 | uint8_t *src_ptr = NULL, *dest_ptr = NULL; |
| 168 | unsigned int src_length = 0, dest_length = 0; |
| 169 | |
| 170 | unsigned int len = 0; |
| 171 | unsigned int i; |
| 172 | uint8_t src_byte; |
| 173 | |
| 174 | int pkt_bnd = HDLC_INCOMPLETE; |
| 175 | int msg_start; |
| 176 | |
| 177 | if (hdlc && hdlc->src_ptr && hdlc->dest_ptr && |
| 178 | (hdlc->src_size > hdlc->src_idx) && |
| 179 | (hdlc->dest_size > hdlc->dest_idx)) { |
| 180 | |
| 181 | msg_start = (hdlc->src_idx == 0) ? 1 : 0; |
| 182 | |
| 183 | src_ptr = hdlc->src_ptr; |
| 184 | src_ptr = &src_ptr[hdlc->src_idx]; |
| 185 | src_length = hdlc->src_size - hdlc->src_idx; |
| 186 | |
| 187 | dest_ptr = hdlc->dest_ptr; |
| 188 | dest_ptr = &dest_ptr[hdlc->dest_idx]; |
| 189 | dest_length = hdlc->dest_size - hdlc->dest_idx; |
| 190 | |
| 191 | for (i = 0; i < src_length; i++) { |
| 192 | |
| 193 | src_byte = src_ptr[i]; |
| 194 | |
| 195 | if (hdlc->escaping) { |
| 196 | dest_ptr[len++] = src_byte ^ ESC_MASK; |
| 197 | hdlc->escaping = 0; |
| 198 | } else if (src_byte == ESC_CHAR) { |
| 199 | if (i == (src_length - 1)) { |
| 200 | hdlc->escaping = 1; |
| 201 | i++; |
| 202 | break; |
| 203 | } else { |
| 204 | dest_ptr[len++] = src_ptr[++i] |
| 205 | ^ ESC_MASK; |
| 206 | } |
| 207 | } else if (src_byte == CONTROL_CHAR) { |
| 208 | if (msg_start && i == 0 && src_length > 1) |
| 209 | continue; |
| 210 | /* Byte 0x7E will be considered |
| 211 | as end of packet */ |
| 212 | dest_ptr[len++] = src_byte; |
| 213 | i++; |
| 214 | pkt_bnd = HDLC_COMPLETE; |
| 215 | break; |
| 216 | } else { |
| 217 | dest_ptr[len++] = src_byte; |
| 218 | } |
| 219 | |
| 220 | if (len >= dest_length) { |
| 221 | i++; |
| 222 | break; |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | hdlc->src_idx += i; |
| 227 | hdlc->dest_idx += len; |
| 228 | } |
| 229 | |
| 230 | return pkt_bnd; |
| 231 | } |
| 232 | |
| 233 | int crc_check(uint8_t *buf, uint16_t len) |
| 234 | { |
| 235 | uint16_t crc = CRC_16_L_SEED; |
| 236 | uint8_t sent_crc[2] = {0, 0}; |
| 237 | |
| 238 | /* |
| 239 | * The minimum length of a valid incoming packet is 4. 1 byte |
| 240 | * of data and 3 bytes for CRC |
| 241 | */ |
| 242 | if (!buf || len < 4) { |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 243 | fprintf(stderr, "diag: In %s, invalid packet or length, buf: 0x%p, len: %d", |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 244 | __func__, buf, len); |
| 245 | return -EIO; |
| 246 | } |
| 247 | |
| 248 | /* |
| 249 | * Run CRC check for the original input. Skip the last 3 CRC |
| 250 | * bytes |
| 251 | */ |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 252 | crc = osmo_crc16_ccitt(crc, buf, len-3); |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 253 | crc ^= CRC_16_L_SEED; |
| 254 | |
| 255 | /* Check the computed CRC against the original CRC bytes. */ |
| 256 | sent_crc[0] = buf[len-3]; |
| 257 | sent_crc[1] = buf[len-2]; |
| 258 | if (crc != *((uint16_t *)sent_crc)) { |
Harald Welte | 6a50b96 | 2016-12-23 22:54:30 +0100 | [diff] [blame] | 259 | fprintf(stderr, "diag: In %s, crc mismatch. expected: %x, sent %x.\n", |
Harald Welte | 99ac1f3 | 2016-12-23 22:07:51 +0100 | [diff] [blame] | 260 | __func__, crc, *((uint16_t *)sent_crc)); |
| 261 | return -EIO; |
| 262 | } |
| 263 | |
| 264 | return 0; |
| 265 | } |