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  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  17  *
  18  * This was originally written for blob and then adapted for busybox.
  19  *
  20  */
  21
  22 #include <stdlib.h>
  23 #include <stdarg.h>
  24 #include <stdio.h>
  25 #include <unistd.h>
  26 #include <errno.h>
  27 #include <termios.h>
  28 #include <signal.h>
  29 #include <sys/types.h>
  30 #include <sys/stat.h>
  31 #include <fcntl.h>
  32 #include <string.h>
  33 #include "busybox.h"
  34
  35
  36 #define SOH 0x01
  37 #define STX 0x02
  38 #define EOT 0x04
  39 #define ACK 0x06
  40 #define NAK 0x15
  41 #define CAN 0x18
  42 #define BS  0x08
  43
  44 /*
  45
  46 Cf:
  47
  48   http://www.textfiles.com/apple/xmodem
  49   http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
  50   http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
  51   http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
  52
  53 */
  54
  55 #define TIMEOUT 1
  56 #define TIMEOUT_LONG 10
  57 #define MAXERRORS 10
  58
  59 static inline void write_byte(int fd, char cc) {
  60         write(fd, &cc, 1);
  61 }
  62
  63 static inline void write_flush(int fd) {
  64         tcdrain(fd);
  65 }
  66
  67 static inline void read_flush(int fd) {
  68         tcflush(fd, TCIFLUSH);
  69 }
  70
  71 static int read_byte(int fd, unsigned int timeout) {
  72         char buf[1];
  73         int n;
  74
  75         alarm(timeout);
  76
  77         n = read(fd, &buf, 1);
  78
  79         alarm(0);
  80
  81         if (n == 1)
  82                 return buf[0] & 0xff;
  83         else
  84                 return -1;
  85 }
  86
  87 static int receive(char *error_buf, size_t error_buf_size,
  88                                    int ttyfd, int filefd)
  89 {
  90         char blockBuf[1024];
  91         unsigned int errors = 0;
  92         unsigned int wantBlockNo = 1;
  93         unsigned int length = 0;
  94         int docrc = 1;
  95         char nak = 'C';
  96         unsigned int timeout = TIMEOUT_LONG;
  97
  98 #define note_error(fmt,args...) \
  99         snprintf(error_buf, error_buf_size, fmt,##args)
 100
 101         read_flush(ttyfd);
 102
 103         /* Ask for CRC; if we get errors, we will go with checksum */
 104         write_byte(ttyfd, nak);
 105         write_flush(ttyfd);
 106
 107         for (;;) {
 108                 int blockBegin;
 109                 int blockNo, blockNoOnesCompl;
 110                 int blockLength;
 111                 int cksum = 0;
 112                 int crcHi = 0;
 113                 int crcLo = 0;
 114
 115                 blockBegin = read_byte(ttyfd, timeout);
 116                 if (blockBegin < 0)
 117                         goto timeout;
 118
 119                 timeout = TIMEOUT;
 120                 nak = NAK;
 121
 122                 switch (blockBegin) {
 123                 case SOH:
 124                 case STX:
 125                         break;
 126
 127                 case EOT:
 128                         write_byte(ttyfd, ACK);
 129                         write_flush(ttyfd);
 130                         goto done;
 131
 132                 default:
 133                         goto error;
 134                 }
 135
 136                 /* block no */
 137                 blockNo = read_byte(ttyfd, TIMEOUT);
 138                 if (blockNo < 0)
 139                         goto timeout;
 140
 141                 /* block no one's compliment */
 142                 blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
 143                 if (blockNoOnesCompl < 0)
 144                         goto timeout;
 145
 146                 if (blockNo != (255 - blockNoOnesCompl)) {
 147                         note_error("bad block ones compl");
 148                         goto error;
 149                 }
 150
 151                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 152
 153                 {
 154                         int i;
 155
 156                         for (i = 0; i < blockLength; i++) {
 157                                 int cc = read_byte(ttyfd, TIMEOUT);
 158                                 if (cc < 0)
 159                                         goto timeout;
 160                                 blockBuf[i] = cc;
 161                         }
 162                 }
 163
 164                 if (docrc) {
 165                         crcHi = read_byte(ttyfd, TIMEOUT);
 166                         if (crcHi < 0)
 167                                 goto timeout;
 168
 169                         crcLo = read_byte(ttyfd, TIMEOUT);
 170                         if (crcLo < 0)
 171                                 goto timeout;
 172                 } else {
 173                         cksum = read_byte(ttyfd, TIMEOUT);
 174                         if (cksum < 0)
 175                                 goto timeout;
 176                 }
 177
 178                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 179                         /* a repeat of the last block is ok, just ignore it. */
 180                         /* this also ignores the initial block 0 which is */
 181                         /* meta data. */
 182                         goto next;
 183                 } else if (blockNo != (wantBlockNo & 0xff)) {
 184                         note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 185                         goto error;
 186                 }
 187
 188                 if (docrc) {
 189                         int crc = 0;
 190                         int i, j;
 191                         int expectedCrcHi;
 192                         int expectedCrcLo;
 193
 194                         for (i = 0; i < blockLength; i++) {
 195                                 crc = crc ^ (int) blockBuf[i] << 8;
 196                                 for (j = 0; j < 8; j++)
 197                                         if (crc & 0x8000)
 198                                                 crc = crc << 1 ^ 0x1021;
 199                                         else
 200                                                 crc = crc << 1;
 201                         }
 202
 203                         expectedCrcHi = (crc >> 8) & 0xff;
 204                         expectedCrcLo = crc & 0xff;
 205
 206                         if ((crcHi != expectedCrcHi) ||
 207                             (crcLo != expectedCrcLo)) {
 208                                 note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
 209                                 goto error;
 210                         }
 211                 } else {
 212                         unsigned char expectedCksum = 0;
 213                         int i;
 214
 215                         for (i = 0; i < blockLength; i++)
 216                                 expectedCksum += blockBuf[i];
 217
 218                         if (cksum != expectedCksum) {
 219                                 note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
 220                                 goto error;
 221                         }
 222                 }
 223
 224                 wantBlockNo++;
 225                 length += blockLength;
 226
 227                 if (bb_full_write(filefd, blockBuf, blockLength) < 0) {
 228                         note_error("write to file failed: %m");
 229                         goto fatal;
 230                 }
 231
 232         next:
 233                 errors = 0;
 234                 write_byte(ttyfd, ACK);
 235                 write_flush(ttyfd);
 236                 continue;
 237
 238         error:
 239         timeout:
 240                 errors++;
 241                 if (errors == MAXERRORS) {
 242                         /* Abort */
 243                         int i;
 244
 245                         // if using crc, try again w/o crc
 246                         if (nak == 'C') {
 247                                 nak = NAK;
 248                                 errors = 0;
 249                                 docrc = 0;
 250                                 goto timeout;
 251                         }
 252
 253                         note_error("too many errors; giving up");
 254
 255                 fatal:
 256                         for (i = 0; i < 5; i ++)
 257                                 write_byte(ttyfd, CAN);
 258                         for (i = 0; i < 5; i ++)
 259                                 write_byte(ttyfd, BS);
 260                         write_flush(ttyfd);
 261                         return -1;
 262                 }
 263
 264                 read_flush(ttyfd);
 265                 write_byte(ttyfd, nak);
 266                 write_flush(ttyfd);
 267         }
 268
 269  done:
 270         return length;
 271
 272 #undef note_error
 273 }
 274
 275 static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
 276 {
 277 }
 278
 279 int rx_main(int argc, char **argv)
 280 {
 281         char *fn;
 282         int ttyfd, filefd;
 283         struct termios tty, orig_tty;
 284         struct sigaction act;
 285         int n;
 286         char error_buf[256];
 287
 288         if (argc != 2)
 289                         bb_show_usage();
 290
 291         fn = argv[1];
 292         ttyfd = open("/dev/tty", O_RDWR);
 293         if (ttyfd < 0)
 294                         bb_error_msg_and_die("%s: open on /dev/tty failed: %m\n", argv[0]);
 295
 296         filefd = open(fn, O_RDWR|O_CREAT|O_TRUNC, 0666);
 297         if (filefd < 0)
 298                         bb_error_msg_and_die("%s: open on %s failed: %m\n", argv[0], fn);
 299
 300         if (tcgetattr(ttyfd, &tty) < 0)
 301                         bb_error_msg_and_die("%s: tcgetattr failed: %m\n", argv[0]);
 302
 303         orig_tty = tty;
 304
 305         cfmakeraw(&tty);
 306         tcsetattr(ttyfd, TCSAFLUSH, &tty);
 307
 308         memset(&act, 0, sizeof(act));
 309         act.sa_handler = sigalrm_handler;
 310         sigaction(SIGALRM, &act, 0);
 311
 312         n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
 313
 314         close(filefd);
 315
 316         tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
 317
 318         if (n < 0)
 319                         bb_error_msg_and_die("\n%s: receive failed:\n  %s\n",
 320                                                            argv[0], error_buf);
 321
 322         bb_fflush_stdout_and_exit(EXIT_SUCCESS);
 323 }
 324
 325 /*
 326 Local Variables:
 327 c-file-style: "linux"
 328 c-basic-offset: 4
 329 tab-width: 4
 330 End:
 331 */