miscutils/rx.c

   1 /* vi: set sw=4 ts=4: */
   2 /*-------------------------------------------------------------------------
   3  * Filename:      xmodem.c
   4  * Version:       $Id: rx.c,v 1.2 2004/03/15 08:28:46 andersen Exp $
   5  * Copyright:     Copyright (C) 2001, Hewlett-Packard Company
   6  * Author:        Christopher Hoover <ch@hpl.hp.com>
   7  * Description:   xmodem functionality for uploading of kernels
   8  *                and the like
   9  * Created at:    Thu Dec 20 01:58:08 PST 2001
  10  *-----------------------------------------------------------------------*/
  11 /*
  12  * xmodem.c: xmodem functionality for uploading of kernels and
  13  *            the like
  14  *
  15  * Copyright (C) 2001 Hewlett-Packard Laboratories
  16  *
  17  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  18  *
  19  * This was originally written for blob and then adapted for busybox.
  20  *
  21  */
  22
  23 #include <stdlib.h>
  24 #include <stdarg.h>
  25 #include <stdio.h>
  26 #include <unistd.h>
  27 #include <errno.h>
  28 #include <termios.h>
  29 #include <signal.h>
  30 #include <sys/types.h>
  31 #include <sys/stat.h>
  32 #include <fcntl.h>
  33 #include <string.h>
  34 #include "busybox.h"
  35
  36
  37 #define SOH 0x01
  38 #define STX 0x02
  39 #define EOT 0x04
  40 #define ACK 0x06
  41 #define NAK 0x15
  42 #define CAN 0x18
  43 #define BS  0x08
  44
  45 /*
  46
  47 Cf:
  48
  49   http://www.textfiles.com/apple/xmodem
  50   http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
  51   http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
  52   http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
  53
  54 */
  55
  56 #define TIMEOUT 1
  57 #define TIMEOUT_LONG 10
  58 #define MAXERRORS 10
  59
  60 static inline void write_byte(int fd, char cc) {
  61         write(fd, &cc, 1);
  62 }
  63
  64 static inline void write_flush(int fd) {
  65         tcdrain(fd);
  66 }
  67
  68 static inline void read_flush(int fd) {
  69         tcflush(fd, TCIFLUSH);
  70 }
  71
  72 static int read_byte(int fd, unsigned int timeout) {
  73         char buf[1];
  74         int n;
  75
  76         alarm(timeout);
  77
  78         n = read(fd, &buf, 1);
  79
  80         alarm(0);
  81
  82         if (n == 1)
  83                 return buf[0] & 0xff;
  84         else
  85                 return -1;
  86 }
  87
  88 static int receive(char *error_buf, size_t error_buf_size,
  89                                    int ttyfd, int filefd)
  90 {
  91         char blockBuf[1024];
  92         unsigned int errors = 0;
  93         unsigned int wantBlockNo = 1;
  94         unsigned int length = 0;
  95         int docrc = 1;
  96         char nak = 'C';
  97         unsigned int timeout = TIMEOUT_LONG;
  98
  99 #define note_error(fmt,args...) \
 100         snprintf(error_buf, error_buf_size, fmt,##args)
 101
 102         read_flush(ttyfd);
 103
 104         /* Ask for CRC; if we get errors, we will go with checksum */
 105         write_byte(ttyfd, nak);
 106         write_flush(ttyfd);
 107
 108         for (;;) {
 109                 int blockBegin;
 110                 int blockNo, blockNoOnesCompl;
 111                 int blockLength;
 112                 int cksum = 0;
 113                 int crcHi = 0;
 114                 int crcLo = 0;
 115
 116                 blockBegin = read_byte(ttyfd, timeout);
 117                 if (blockBegin < 0)
 118                         goto timeout;
 119
 120                 timeout = TIMEOUT;
 121                 nak = NAK;
 122
 123                 switch (blockBegin) {
 124                 case SOH:
 125                 case STX:
 126                         break;
 127
 128                 case EOT:
 129                         write_byte(ttyfd, ACK);
 130                         write_flush(ttyfd);
 131                         goto done;
 132
 133                 default:
 134                         goto error;
 135                 }
 136
 137                 /* block no */
 138                 blockNo = read_byte(ttyfd, TIMEOUT);
 139                 if (blockNo < 0)
 140                         goto timeout;
 141
 142                 /* block no one's compliment */
 143                 blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
 144                 if (blockNoOnesCompl < 0)
 145                         goto timeout;
 146
 147                 if (blockNo != (255 - blockNoOnesCompl)) {
 148                         note_error("bad block ones compl");
 149                         goto error;
 150                 }
 151
 152                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 153
 154                 {
 155                         int i;
 156
 157                         for (i = 0; i < blockLength; i++) {
 158                                 int cc = read_byte(ttyfd, TIMEOUT);
 159                                 if (cc < 0)
 160                                         goto timeout;
 161                                 blockBuf[i] = cc;
 162                         }
 163                 }
 164
 165                 if (docrc) {
 166                         crcHi = read_byte(ttyfd, TIMEOUT);
 167                         if (crcHi < 0)
 168                                 goto timeout;
 169
 170                         crcLo = read_byte(ttyfd, TIMEOUT);
 171                         if (crcLo < 0)
 172                                 goto timeout;
 173                 } else {
 174                         cksum = read_byte(ttyfd, TIMEOUT);
 175                         if (cksum < 0)
 176                                 goto timeout;
 177                 }
 178
 179                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 180                         /* a repeat of the last block is ok, just ignore it. */
 181                         /* this also ignores the initial block 0 which is */
 182                         /* meta data. */
 183                         goto next;
 184                 } else if (blockNo != (wantBlockNo & 0xff)) {
 185                         note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 186                         goto error;
 187                 }
 188
 189                 if (docrc) {
 190                         int crc = 0;
 191                         int i, j;
 192                         int expectedCrcHi;
 193                         int expectedCrcLo;
 194
 195                         for (i = 0; i < blockLength; i++) {
 196                                 crc = crc ^ (int) blockBuf[i] << 8;
 197                                 for (j = 0; j < 8; j++)
 198                                         if (crc & 0x8000)
 199                                                 crc = crc << 1 ^ 0x1021;
 200                                         else
 201                                                 crc = crc << 1;
 202                         }
 203
 204                         expectedCrcHi = (crc >> 8) & 0xff;
 205                         expectedCrcLo = crc & 0xff;
 206
 207                         if ((crcHi != expectedCrcHi) ||
 208                             (crcLo != expectedCrcLo)) {
 209                                 note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
 210                                 goto error;
 211                         }
 212                 } else {
 213                         unsigned char expectedCksum = 0;
 214                         int i;
 215
 216                         for (i = 0; i < blockLength; i++)
 217                                 expectedCksum += blockBuf[i];
 218
 219                         if (cksum != expectedCksum) {
 220                                 note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
 221                                 goto error;
 222                         }
 223                 }
 224
 225                 wantBlockNo++;
 226                 length += blockLength;
 227
 228                 if (bb_full_write(filefd, blockBuf, blockLength) < 0) {
 229                         note_error("write to file failed: %m");
 230                         goto fatal;
 231                 }
 232
 233         next:
 234                 errors = 0;
 235                 write_byte(ttyfd, ACK);
 236                 write_flush(ttyfd);
 237                 continue;
 238
 239         error:
 240         timeout:
 241                 errors++;
 242                 if (errors == MAXERRORS) {
 243                         /* Abort */
 244                         int i;
 245
 246                         // if using crc, try again w/o crc
 247                         if (nak == 'C') {
 248                                 nak = NAK;
 249                                 errors = 0;
 250                                 docrc = 0;
 251                                 goto timeout;
 252                         }
 253
 254                         note_error("too many errors; giving up");
 255
 256                 fatal:
 257                         for (i = 0; i < 5; i ++)
 258                                 write_byte(ttyfd, CAN);
 259                         for (i = 0; i < 5; i ++)
 260                                 write_byte(ttyfd, BS);
 261                         write_flush(ttyfd);
 262                         return -1;
 263                 }
 264
 265                 read_flush(ttyfd);
 266                 write_byte(ttyfd, nak);
 267                 write_flush(ttyfd);
 268         }
 269
 270  done:
 271         return length;
 272
 273 #undef note_error
 274 }
 275
 276 static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
 277 {
 278 }
 279
 280 int rx_main(int argc, char **argv)
 281 {
 282         char *fn;
 283         int ttyfd, filefd;
 284         struct termios tty, orig_tty;
 285         struct sigaction act;
 286         int n;
 287         char error_buf[256];
 288
 289         if (argc != 2)
 290                         bb_show_usage();
 291
 292         fn = argv[1];
 293         ttyfd = bb_xopen3("/dev/tty", O_RDWR, 0);
 294         filefd = bb_xopen3(fn, O_RDWR|O_CREAT|O_TRUNC, 0666);
 295
 296         if (tcgetattr(ttyfd, &tty) < 0)
 297                         bb_error_msg_and_die("%s: tcgetattr failed: %m\n", argv[0]);
 298
 299         orig_tty = tty;
 300
 301         cfmakeraw(&tty);
 302         tcsetattr(ttyfd, TCSAFLUSH, &tty);
 303
 304         memset(&act, 0, sizeof(act));
 305         act.sa_handler = sigalrm_handler;
 306         sigaction(SIGALRM, &act, 0);
 307
 308         n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
 309
 310         close(filefd);
 311
 312         tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
 313
 314         if (n < 0)
 315                         bb_error_msg_and_die("\n%s: receive failed:\n  %s\n",
 316                                                            argv[0], error_buf);
 317
 318         bb_fflush_stdout_and_exit(EXIT_SUCCESS);
 319 }