miscutils/rx.c

   1 /* vi: set sw=4 ts=4: */
   2 /*-------------------------------------------------------------------------
   3  * Filename:      xmodem.c
   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 "busybox.h"
  23
  24 #define SOH 0x01
  25 #define STX 0x02
  26 #define EOT 0x04
  27 #define ACK 0x06
  28 #define NAK 0x15
  29 #define BS  0x08
  30
  31 /*
  32
  33 Cf:
  34
  35   http://www.textfiles.com/apple/xmodem
  36   http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
  37   http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
  38   http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
  39
  40 */
  41
  42 #define TIMEOUT 1
  43 #define TIMEOUT_LONG 10
  44 #define MAXERRORS 10
  45
  46 static int read_byte(int fd, unsigned int timeout) {
  47         char buf[1];
  48         int n;
  49
  50         alarm(timeout);
  51
  52         n = read(fd, &buf, 1);
  53
  54         alarm(0);
  55
  56         if (n == 1)
  57                 return buf[0] & 0xff;
  58         else
  59                 return -1;
  60 }
  61
  62 static int receive(char *error_buf, size_t error_buf_size,
  63                                    int ttyfd, int filefd)
  64 {
  65         char blockBuf[1024];
  66         unsigned int errors = 0;
  67         unsigned int wantBlockNo = 1;
  68         unsigned int length = 0;
  69         int docrc = 1;
  70         char nak = 'C';
  71         unsigned int timeout = TIMEOUT_LONG;
  72
  73 #define note_error(fmt,args...) \
  74         snprintf(error_buf, error_buf_size, fmt,##args)
  75
  76         /* Flush pending input */
  77         tcflush(ttyfd, TCIFLUSH);
  78
  79         /* Ask for CRC; if we get errors, we will go with checksum */
  80         write(ttyfd, &nak, 1);
  81
  82         for (;;) {
  83                 int blockBegin;
  84                 int blockNo, blockNoOnesCompl;
  85                 int blockLength;
  86                 int cksum = 0;
  87                 int crcHi = 0;
  88                 int crcLo = 0;
  89
  90                 blockBegin = read_byte(ttyfd, timeout);
  91                 if (blockBegin < 0)
  92                         goto timeout;
  93
  94                 timeout = TIMEOUT;
  95                 nak = NAK;
  96
  97                 switch (blockBegin) {
  98                 case SOH:
  99                 case STX:
 100                         break;
 101
 102                 case EOT:
 103                         nak = ACK;
 104                         write(ttyfd, &nak, 1);
 105                         goto done;
 106
 107                 default:
 108                         goto error;
 109                 }
 110
 111                 /* block no */
 112                 blockNo = read_byte(ttyfd, TIMEOUT);
 113                 if (blockNo < 0)
 114                         goto timeout;
 115
 116                 /* block no one's compliment */
 117                 blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
 118                 if (blockNoOnesCompl < 0)
 119                         goto timeout;
 120
 121                 if (blockNo != (255 - blockNoOnesCompl)) {
 122                         note_error("bad block ones compl");
 123                         goto error;
 124                 }
 125
 126                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 127
 128                 {
 129                         int i;
 130
 131                         for (i = 0; i < blockLength; i++) {
 132                                 int cc = read_byte(ttyfd, TIMEOUT);
 133                                 if (cc < 0)
 134                                         goto timeout;
 135                                 blockBuf[i] = cc;
 136                         }
 137                 }
 138
 139                 if (docrc) {
 140                         crcHi = read_byte(ttyfd, TIMEOUT);
 141                         if (crcHi < 0)
 142                                 goto timeout;
 143
 144                         crcLo = read_byte(ttyfd, TIMEOUT);
 145                         if (crcLo < 0)
 146                                 goto timeout;
 147                 } else {
 148                         cksum = read_byte(ttyfd, TIMEOUT);
 149                         if (cksum < 0)
 150                                 goto timeout;
 151                 }
 152
 153                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 154                         /* a repeat of the last block is ok, just ignore it. */
 155                         /* this also ignores the initial block 0 which is */
 156                         /* meta data. */
 157                         goto next;
 158                 } else if (blockNo != (wantBlockNo & 0xff)) {
 159                         note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 160                         goto error;
 161                 }
 162
 163                 if (docrc) {
 164                         int crc = 0;
 165                         int i, j;
 166                         int expectedCrcHi;
 167                         int expectedCrcLo;
 168
 169                         for (i = 0; i < blockLength; i++) {
 170                                 crc = crc ^ (int) blockBuf[i] << 8;
 171                                 for (j = 0; j < 8; j++)
 172                                         if (crc & 0x8000)
 173                                                 crc = crc << 1 ^ 0x1021;
 174                                         else
 175                                                 crc = crc << 1;
 176                         }
 177
 178                         expectedCrcHi = (crc >> 8) & 0xff;
 179                         expectedCrcLo = crc & 0xff;
 180
 181                         if ((crcHi != expectedCrcHi) ||
 182                             (crcLo != expectedCrcLo)) {
 183                                 note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
 184                                 goto error;
 185                         }
 186                 } else {
 187                         unsigned char expectedCksum = 0;
 188                         int i;
 189
 190                         for (i = 0; i < blockLength; i++)
 191                                 expectedCksum += blockBuf[i];
 192
 193                         if (cksum != expectedCksum) {
 194                                 note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
 195                                 goto error;
 196                         }
 197                 }
 198
 199                 wantBlockNo++;
 200                 length += blockLength;
 201
 202                 if (full_write(filefd, blockBuf, blockLength) < 0) {
 203                         note_error("write to file failed: %m");
 204                         goto fatal;
 205                 }
 206
 207         next:
 208                 errors = 0;
 209                 nak = ACK;
 210                 write(ttyfd, &nak, 1);
 211                 continue;
 212
 213         error:
 214         timeout:
 215                 errors++;
 216                 if (errors == MAXERRORS) {
 217                         /* Abort */
 218
 219                         // if using crc, try again w/o crc
 220                         if (nak == 'C') {
 221                                 nak = NAK;
 222                                 errors = 0;
 223                                 docrc = 0;
 224                                 goto timeout;
 225                         }
 226
 227                         note_error("too many errors; giving up");
 228
 229                 fatal:
 230                         /* 5 CAN followed by 5 BS */
 231                         write(ttyfd, "\030\030\030\030\030\010\010\010\010\010", 10);
 232                         return -1;
 233                 }
 234
 235                 /* Flush pending input */
 236                 tcflush(ttyfd, TCIFLUSH);
 237
 238                 write(ttyfd, &nak, 1);
 239         }
 240
 241  done:
 242         return length;
 243
 244 #undef note_error
 245 }
 246
 247 static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
 248 {
 249 }
 250
 251 int rx_main(int argc, char **argv)
 252 {
 253         char *fn;
 254         int ttyfd, filefd;
 255         struct termios tty, orig_tty;
 256         struct sigaction act;
 257         int n;
 258         char error_buf[256];
 259
 260         if (argc != 2)
 261                         bb_show_usage();
 262
 263         fn = argv[1];
 264         ttyfd = xopen(CURRENT_TTY, O_RDWR);
 265         filefd = xopen(fn, O_RDWR|O_CREAT|O_TRUNC);
 266
 267         if (tcgetattr(ttyfd, &tty) < 0)
 268                         bb_perror_msg_and_die("tcgetattr");
 269
 270         orig_tty = tty;
 271
 272         cfmakeraw(&tty);
 273         tcsetattr(ttyfd, TCSAFLUSH, &tty);
 274
 275         memset(&act, 0, sizeof(act));
 276         act.sa_handler = sigalrm_handler;
 277         sigaction(SIGALRM, &act, 0);
 278
 279         n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
 280
 281         close(filefd);
 282
 283         tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
 284
 285         if (n < 0)
 286                 bb_error_msg_and_die("\nreceive failed:\n  %s", error_buf);
 287
 288         fflush_stdout_and_exit(EXIT_SUCCESS);
 289 }