2009-09-05 05:30:18 +00:00
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/*
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*
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2009-09-05 22:25:16 +00:00
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* AT chat library with GLib integration
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2009-09-05 05:30:18 +00:00
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*
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2010-01-02 01:00:10 +00:00
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* Copyright (C) 2010 Intel Corporation. All rights reserved.
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2009-09-05 05:30:18 +00:00
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* Copyright (C) 2009 Trolltech ASA.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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2009-09-05 04:57:11 +00:00
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2009-09-05 05:25:31 +00:00
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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2009-09-05 04:57:11 +00:00
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#include <string.h>
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2009-10-14 20:50:55 +00:00
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#include <glib.h>
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2009-09-05 04:57:11 +00:00
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2009-10-14 20:50:55 +00:00
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#include "gsm0710.h"
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2009-09-05 04:57:11 +00:00
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2009-09-05 05:09:46 +00:00
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static const unsigned char crc_table[256] = {
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2009-09-05 22:08:53 +00:00
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0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
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0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
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0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
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0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
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0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
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0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
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0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
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0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
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0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
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0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
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0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
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0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
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0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
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0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
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0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
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0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
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0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
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0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
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0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
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0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
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0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
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0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
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0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
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0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
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0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
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0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
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0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
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0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
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0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
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0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
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0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
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0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
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2009-09-05 05:09:46 +00:00
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};
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2009-10-14 20:50:55 +00:00
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static inline guint8 gsm0710_crc(const guint8 *data, int len)
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2009-09-05 05:09:46 +00:00
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{
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2009-10-14 20:50:55 +00:00
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guint8 crc = 0xFF;
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int i;
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for (i = 0; i < len; i++)
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crc = crc_table[crc ^ data[i]];
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return crc;
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2009-09-05 05:09:46 +00:00
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}
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2009-10-14 20:50:55 +00:00
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static inline guint8 gsm0710_fcs(const guint8 *data, int len)
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2009-09-05 05:09:46 +00:00
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{
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2009-10-14 20:50:55 +00:00
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return 0xff - gsm0710_crc(data, len);
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2009-09-05 05:09:46 +00:00
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}
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2009-10-14 20:50:55 +00:00
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static inline gboolean gsm0710_check_fcs(const guint8 *data, int len,
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guint8 cfcs)
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2009-09-05 04:57:11 +00:00
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{
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2009-10-14 20:50:55 +00:00
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guint8 fcs = gsm0710_crc(data, len);
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fcs = crc_table[fcs ^ cfcs];
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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if (fcs == 0xcf)
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return TRUE;
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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return FALSE;
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2009-09-05 04:57:11 +00:00
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}
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2009-10-14 20:50:55 +00:00
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int gsm0710_advanced_extract_frame(guint8 *buf, int len,
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guint8 *out_dlc, guint8 *out_control,
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guint8 **out_frame, int *out_len)
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2009-09-05 04:57:11 +00:00
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{
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2009-10-14 20:50:55 +00:00
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int posn = 0;
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int posn2;
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int framelen;
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guint8 dlc;
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guint8 control;
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while (posn < len) {
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if (buf[posn] != 0x7E) {
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posn += 1;
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continue;
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}
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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/* Skip additional 0x7E bytes between frames */
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while ((posn + 1) < len && buf[posn + 1] == 0x7E)
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posn += 1;
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/* Search for the end of the packet (the next 0x7E byte) */
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framelen = posn + 1;
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while (framelen < len && buf[framelen] != 0x7E)
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framelen += 1;
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if (framelen >= len)
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break;
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if (framelen < 4) {
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posn = framelen;
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2009-10-06 23:21:01 +00:00
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continue;
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2009-10-14 20:50:55 +00:00
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}
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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/* Undo control byte quoting in the packet */
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posn2 = 0;
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++posn;
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while (posn < framelen) {
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if (buf[posn] == 0x7D) {
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++posn;
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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if (posn >= framelen)
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break;
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2009-09-05 04:57:11 +00:00
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2009-10-14 20:50:55 +00:00
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buf[posn2++] = buf[posn++] ^ 0x20;
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} else {
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buf[posn2++] = buf[posn++];
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}
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}
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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/* Validate the checksum on the packet header */
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if (!gsm0710_check_fcs(buf, 2, buf[posn2 - 1]))
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continue;
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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/* Decode and dispatch the packet */
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dlc = (buf[0] >> 2) & 0x3F;
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control = buf[1] & 0xEF; /* Strip "PF" bit */
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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if (out_frame)
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*out_frame = buf + 2;
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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if (out_len)
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*out_len = posn2 - 3;
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2009-09-05 04:57:11 +00:00
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2009-10-14 20:50:55 +00:00
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if (out_dlc)
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*out_dlc = dlc;
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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if (out_control)
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*out_control = control;
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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break;
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}
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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return posn;
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2009-09-05 04:57:11 +00:00
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}
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2009-10-14 20:50:55 +00:00
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int gsm0710_advanced_fill_frame(guint8 *frame, guint8 dlc, guint8 type,
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const guint8 *data, int len)
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2009-09-05 04:57:11 +00:00
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{
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2009-10-14 20:50:55 +00:00
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int temp, crc;
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int size;
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2009-09-05 04:57:11 +00:00
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2009-10-14 20:50:55 +00:00
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frame[0] = 0x7E;
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frame[1] = ((dlc << 2) | 0x03);
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frame[2] = type;
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crc = gsm0710_fcs(frame + 1, 2);
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/* The Address field might need to be escaped if this is a response
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* frame
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*/
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/* Need to quote the type field now that crc has been computed */
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if (type == 0x7E || type == 0x7D) {
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frame[2] = 0x7D;
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frame[3] = (type ^ 0x20);
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size = 4;
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} else {
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size = 3;
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2009-09-05 22:08:53 +00:00
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}
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2009-10-14 20:50:55 +00:00
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while (len > 0) {
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temp = *data++ & 0xFF;
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--len;
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if (temp != 0x7E && temp != 0x7D) {
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frame[size++] = temp;
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} else {
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frame[size++] = 0x7D;
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frame[size++] = (temp ^ 0x20);
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2009-09-05 22:08:53 +00:00
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}
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2009-10-14 20:50:55 +00:00
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}
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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if (crc != 0x7E && crc != 0x7D) {
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frame[size++] = crc;
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} else {
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frame[size++] = 0x7D;
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frame[size++] = (crc ^ 0x20);
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2009-09-05 22:08:53 +00:00
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}
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2009-10-06 23:21:01 +00:00
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2009-10-14 20:50:55 +00:00
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frame[size++] = 0x7E;
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return size;
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2009-09-05 04:57:11 +00:00
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}
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2009-10-14 20:50:55 +00:00
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int gsm0710_basic_extract_frame(guint8 *buf, int len,
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guint8 *out_dlc, guint8 *out_control,
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guint8 **out_frame, int *out_len)
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2009-09-05 04:57:11 +00:00
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{
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2009-10-14 20:50:55 +00:00
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int posn = 0;
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int framelen;
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int header_size;
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guint8 fcs;
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guint8 dlc;
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guint8 type;
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while (posn < len) {
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if (buf[posn] != 0xF9) {
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posn += 1;
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continue;
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}
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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/* Skip additional 0xF9 bytes between frames */
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while ((posn + 1) < len && buf[posn + 1] == 0xF9)
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posn += 1;
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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/* We need at least 4 bytes for the flag + header */
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if ((posn + 4) > len)
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break;
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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/* The low bit of the second byte should be 1,
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which indicates a short channel number. According to
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27.010 Section 5.2.3, if this is not true, then
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the frame is invalid and should be discarded
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*/
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if ((buf[posn + 1] & 0x01) == 0) {
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++posn;
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continue;
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}
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/* Get the packet length and validate it */
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framelen = buf[posn + 3] >> 1;
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if ((buf[posn + 3] & 0x01) != 0) {
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/* Single-byte length indication */
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header_size = 3;
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} else {
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/* Double-byte length indication */
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if ((posn + 5) > len)
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2009-09-05 22:08:53 +00:00
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break;
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2009-10-14 20:50:55 +00:00
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framelen |= buf[posn + 4] << 7;
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header_size = 4;
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}
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2009-09-05 22:08:53 +00:00
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2009-10-14 20:50:55 +00:00
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/* Total size of the packet is the flag + 3 or 4 byte header
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* Address Control Length followed by Information and FCS.
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* However, we must check the presence of the end flag
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* according to 27.010 Section 5.2.3
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*/
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if ((posn + header_size + 3 + framelen) > len)
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break;
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fcs = buf[posn + 1 + header_size + framelen];
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/*
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* The end flag is not guaranteed to be only ours
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* according to 27.010 Section 5.2.6.1:
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* "The closing flag may also be the opening flag of the
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* following frame", thus we do not consume it in the following
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* stages
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*/
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/*
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* If FCS is invalid, discard the packet in accordance to
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* Section 5.2.3 of 27.010
|
|
|
|
*/
|
|
|
|
if (!gsm0710_check_fcs(buf + posn + 1, header_size, fcs)) {
|
|
|
|
posn += header_size + framelen + 2;
|
|
|
|
continue;
|
|
|
|
}
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
if (buf[posn + header_size + framelen + 2] != 0xF9) {
|
|
|
|
posn += header_size + framelen + 2;
|
|
|
|
continue;
|
|
|
|
}
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
/* Get the channel number and packet type from the header */
|
|
|
|
dlc = buf[posn + 1] >> 2;
|
|
|
|
type = buf[posn + 2] & 0xEF; /* Strip "PF" bit */
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
if (out_frame)
|
|
|
|
*out_frame = buf + posn + 1 + header_size;
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
if (out_len)
|
|
|
|
*out_len = framelen;
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
if (out_dlc)
|
|
|
|
*out_dlc = dlc;
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
if (out_control)
|
|
|
|
*out_control = type;
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
posn += header_size + framelen + 2;
|
2009-09-05 22:08:53 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
break;
|
2009-09-05 22:08:53 +00:00
|
|
|
}
|
2009-10-14 20:50:55 +00:00
|
|
|
|
|
|
|
return posn;
|
2009-09-05 04:57:11 +00:00
|
|
|
}
|
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
int gsm0710_basic_fill_frame(guint8 *frame, guint8 dlc, guint8 type,
|
|
|
|
const guint8 *data, int len)
|
2009-09-05 04:57:11 +00:00
|
|
|
{
|
2009-10-14 20:50:55 +00:00
|
|
|
int size;
|
|
|
|
int header_size;
|
|
|
|
|
|
|
|
frame[0] = 0xF9;
|
|
|
|
frame[1] = ((dlc << 2) | 0x03);
|
|
|
|
frame[2] = type;
|
|
|
|
|
|
|
|
if (len <= 127) {
|
|
|
|
frame[3] = ((len << 1) | 0x01);
|
|
|
|
header_size = 4;
|
|
|
|
} else {
|
|
|
|
frame[3] = (len << 1);
|
|
|
|
frame[4] = (len >> 7);
|
|
|
|
header_size = 5;
|
2009-09-05 22:08:53 +00:00
|
|
|
}
|
2009-09-05 04:57:11 +00:00
|
|
|
|
2009-10-14 20:50:55 +00:00
|
|
|
size = header_size;
|
|
|
|
|
|
|
|
if (len > 0) {
|
|
|
|
memcpy(frame + header_size, data, len);
|
|
|
|
size += len;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Note: GSM 07.10 says that the CRC is only computed over the header */
|
|
|
|
frame[size++] = gsm0710_fcs(frame + 1, header_size - 1);
|
|
|
|
frame[size++] = 0xF9;
|
|
|
|
|
|
|
|
return size;
|
2009-09-05 04:57:11 +00:00
|
|
|
}
|