miscutils/rx.c

   1 /*-------------------------------------------------------------------------
   2  * Filename:      xmodem.c
   3  * Version:       $Id: rx.c,v 1.2 2004/03/15 08:28:46 andersen Exp $
   4  * Copyright:     Copyright (C) 2001, Hewlett-Packard Company
   5  * Author:        Christopher Hoover <ch@hpl.hp.com>
   6  * Description:   xmodem functionality for uploading of kernels
   7  *                and the like
   8  * Created at:    Thu Dec 20 01:58:08 PST 2001
   9  *-----------------------------------------------------------------------*/
  10 /*
  11  * xmodem.c: xmodem functionality for uploading of kernels and
  12  *            the like
  13  *
  14  * Copyright (C) 2001 Hewlett-Packard Laboratories
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful,
  22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  * GNU General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with this program; if not, write to the Free Software
  28  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  29  *
  30  *
  31  * This was originally written for blob and then adapted for busybox.
  32  *
  33  */
  34
  35 #include <stdlib.h>
  36 #include <stdarg.h>
  37 #include <stdio.h>
  38 #include <unistd.h>
  39 #include <errno.h>
  40 #include <termios.h>
  41 #include <signal.h>
  42 #include <sys/types.h>
  43 #include <sys/stat.h>
  44 #include <fcntl.h>
  45 #include <string.h>
  46 #include "busybox.h"
  47
  48
  49 #define SOH 0x01
  50 #define STX 0x02
  51 #define EOT 0x04
  52 #define ACK 0x06
  53 #define NAK 0x15
  54 #define CAN 0x18
  55 #define BS  0x08
  56
  57 /*
  58
  59 Cf:
  60
  61   http://www.textfiles.com/apple/xmodem
  62   http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
  63   http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
  64   http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
  65
  66 */
  67
  68 #define TIMEOUT 1
  69 #define TIMEOUT_LONG 10
  70 #define MAXERRORS 10
  71
  72 static inline void write_byte(int fd, char cc) {
  73         write(fd, &cc, 1);
  74 }
  75
  76 static inline void write_flush(int fd) {
  77         tcdrain(fd);
  78 }
  79
  80 static inline void read_flush(int fd) {
  81         tcflush(fd, TCIFLUSH);
  82 }
  83
  84 static int read_byte(int fd, unsigned int timeout) {
  85         char buf[1];
  86         int n;
  87
  88         alarm(timeout);
  89
  90         n = read(fd, &buf, 1);
  91
  92         alarm(0);
  93
  94         if (n == 1)
  95                 return buf[0] & 0xff;
  96         else
  97                 return -1;
  98 }
  99
 100 static int receive(char *error_buf, size_t error_buf_size,
 101                                    int ttyfd, int filefd)
 102 {
 103         char blockBuf[1024];
 104         unsigned int errors = 0;
 105         unsigned int wantBlockNo = 1;
 106         unsigned int length = 0;
 107         int docrc = 1;
 108         char nak = 'C';
 109         unsigned int timeout = TIMEOUT_LONG;
 110
 111 #define note_error(fmt,args...) \
 112         snprintf(error_buf, error_buf_size, fmt,##args)
 113
 114         read_flush(ttyfd);
 115
 116         /* Ask for CRC; if we get errors, we will go with checksum */
 117         write_byte(ttyfd, nak);
 118         write_flush(ttyfd);
 119
 120         for (;;) {
 121                 int blockBegin;
 122                 int blockNo, blockNoOnesCompl;
 123                 int blockLength;
 124                 int cksum = 0;
 125                 int crcHi = 0;
 126                 int crcLo = 0;
 127
 128                 blockBegin = read_byte(ttyfd, timeout);
 129                 if (blockBegin < 0)
 130                         goto timeout;
 131
 132                 timeout = TIMEOUT;
 133                 nak = NAK;
 134
 135                 switch (blockBegin) {
 136                 case SOH:
 137                 case STX:
 138                         break;
 139
 140                 case EOT:
 141                         write_byte(ttyfd, ACK);
 142                         write_flush(ttyfd);
 143                         goto done;
 144
 145                 default:
 146                         goto error;
 147                 }
 148
 149                 /* block no */
 150                 blockNo = read_byte(ttyfd, TIMEOUT);
 151                 if (blockNo < 0)
 152                         goto timeout;
 153
 154                 /* block no one's compliment */
 155                 blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
 156                 if (blockNoOnesCompl < 0)
 157                         goto timeout;
 158
 159                 if (blockNo != (255 - blockNoOnesCompl)) {
 160                         note_error("bad block ones compl");
 161                         goto error;
 162                 }
 163
 164                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 165
 166                 {
 167                         int i;
 168
 169                         for (i = 0; i < blockLength; i++) {
 170                                 int cc = read_byte(ttyfd, TIMEOUT);
 171                                 if (cc < 0)
 172                                         goto timeout;
 173                                 blockBuf[i] = cc;
 174                         }
 175                 }
 176
 177                 if (docrc) {
 178                         crcHi = read_byte(ttyfd, TIMEOUT);
 179                         if (crcHi < 0)
 180                                 goto timeout;
 181
 182                         crcLo = read_byte(ttyfd, TIMEOUT);
 183                         if (crcLo < 0)
 184                                 goto timeout;
 185                 } else {
 186                         cksum = read_byte(ttyfd, TIMEOUT);
 187                         if (cksum < 0)
 188                                 goto timeout;
 189                 }
 190
 191                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 192                         /* a repeat of the last block is ok, just ignore it. */
 193                         /* this also ignores the initial block 0 which is */
 194                         /* meta data. */
 195                         goto next;
 196                 } else if (blockNo != (wantBlockNo & 0xff)) {
 197                         note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 198                         goto error;
 199                 }
 200
 201                 if (docrc) {
 202                         int crc = 0;
 203                         int i, j;
 204                         int expectedCrcHi;
 205                         int expectedCrcLo;
 206
 207                         for (i = 0; i < blockLength; i++) {
 208                                 crc = crc ^ (int) blockBuf[i] << 8;
 209                                 for (j = 0; j < 8; j++)
 210                                         if (crc & 0x8000)
 211                                                 crc = crc << 1 ^ 0x1021;
 212                                         else
 213                                                 crc = crc << 1;
 214                         }
 215
 216                         expectedCrcHi = (crc >> 8) & 0xff;
 217                         expectedCrcLo = crc & 0xff;
 218
 219                         if ((crcHi != expectedCrcHi) ||
 220                             (crcLo != expectedCrcLo)) {
 221                                 note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
 222                                 goto error;
 223                         }
 224                 } else {
 225                         unsigned char expectedCksum = 0;
 226                         int i;
 227
 228                         for (i = 0; i < blockLength; i++)
 229                                 expectedCksum += blockBuf[i];
 230
 231                         if (cksum != expectedCksum) {
 232                                 note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
 233                                 goto error;
 234                         }
 235                 }
 236
 237                 wantBlockNo++;
 238                 length += blockLength;
 239
 240                 if (bb_full_write(filefd, blockBuf, blockLength) < 0) {
 241                         note_error("write to file failed: %m");
 242                         goto fatal;
 243                 }
 244
 245         next:
 246                 errors = 0;
 247                 write_byte(ttyfd, ACK);
 248                 write_flush(ttyfd);
 249                 continue;
 250
 251         error:
 252         timeout:
 253                 errors++;
 254                 if (errors == MAXERRORS) {
 255                         /* Abort */
 256                         int i;
 257
 258                         // if using crc, try again w/o crc
 259                         if (nak == 'C') {
 260                                 nak = NAK;
 261                                 errors = 0;
 262                                 docrc = 0;
 263                                 goto timeout;
 264                         }
 265
 266                         note_error("too many errors; giving up");
 267
 268                 fatal:
 269                         for (i = 0; i < 5; i ++)
 270                                 write_byte(ttyfd, CAN);
 271                         for (i = 0; i < 5; i ++)
 272                                 write_byte(ttyfd, BS);
 273                         write_flush(ttyfd);
 274                         return -1;
 275                 }
 276
 277                 read_flush(ttyfd);
 278                 write_byte(ttyfd, nak);
 279                 write_flush(ttyfd);
 280         }
 281
 282  done:
 283         return length;
 284
 285 #undef note_error
 286 }
 287
 288 static void sigalrm_handler(int signum)
 289 {
 290 }
 291
 292 int rx_main(int argc, char **argv)
 293 {
 294         char *fn;
 295         int ttyfd, filefd;
 296         struct termios tty, orig_tty;
 297         struct sigaction act;
 298         int n;
 299         char error_buf[256];
 300
 301         if (argc != 2)
 302                         bb_show_usage();
 303
 304         fn = argv[1];
 305         ttyfd = open("/dev/tty", O_RDWR);
 306         if (ttyfd < 0)
 307                         bb_error_msg_and_die("%s: open on /dev/tty failed: %m\n", argv[0]);
 308
 309         filefd = open(fn, O_RDWR|O_CREAT|O_TRUNC, 0666);
 310         if (filefd < 0)
 311                         bb_error_msg_and_die("%s: open on %s failed: %m\n", argv[0], fn);
 312
 313         if (tcgetattr(ttyfd, &tty) < 0)
 314                         bb_error_msg_and_die("%s: tcgetattr failed: %m\n", argv[0]);
 315
 316         orig_tty = tty;
 317
 318         cfmakeraw(&tty);
 319         tcsetattr(ttyfd, TCSAFLUSH, &tty);
 320
 321         memset(&act, 0, sizeof(act));
 322         act.sa_handler = sigalrm_handler;
 323         sigaction(SIGALRM, &act, 0);
 324
 325         n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
 326
 327         close(filefd);
 328
 329         tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
 330
 331         if (n < 0)
 332                         bb_error_msg_and_die("\n%s: receive failed:\n  %s\n",
 333                                                            argv[0], error_buf);
 334
 335         bb_fflush_stdout_and_exit(EXIT_SUCCESS);
 336 }
 337
 338 /*
 339 Local Variables:
 340 c-file-style: "linux"
 341 c-basic-offset: 4
 342 tab-width: 4
 343 End:
 344 */