git.maemo.org Git - busybox4maemo/blob - 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 #include "libbb.h"
  22
  23 #define SOH 0x01
  24 #define STX 0x02
  25 #define EOT 0x04
  26 #define ACK 0x06
  27 #define NAK 0x15
  28 #define BS  0x08
  29
  30 /*
  31 Cf:
  32   http://www.textfiles.com/apple/xmodem
  33   http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
  34   http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
  35   http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
  36 */
  37
  38 #define TIMEOUT 1
  39 #define TIMEOUT_LONG 10
  40 #define MAXERRORS 10
  41
  42 #define read_fd  STDIN_FILENO
  43 #define write_fd STDOUT_FILENO
  44
  45 static int read_byte(unsigned timeout)
  46 {
  47         char buf[1];
  48         int n;
  49
  50         alarm(timeout);
  51         /* NOT safe_read! We want ALRM to interrupt us */
  52         n = read(read_fd, buf, 1);
  53         alarm(0);
  54         if (n == 1)
  55                 return (unsigned char)buf[0];
  56         return -1;
  57 }
  58
  59 static int receive(/*int read_fd, */int file_fd)
  60 {
  61         unsigned char blockBuf[1024];
  62         unsigned errors = 0;
  63         unsigned wantBlockNo = 1;
  64         unsigned length = 0;
  65         int do_crc = 1;
  66         char nak = 'C';
  67         unsigned timeout = TIMEOUT_LONG;
  68
  69         /* Flush pending input */
  70         tcflush(read_fd, TCIFLUSH);
  71
  72         /* Ask for CRC; if we get errors, we will go with checksum */
  73         full_write(write_fd, &nak, 1);
  74
  75         for (;;) {
  76                 int blockBegin;
  77                 int blockNo, blockNoOnesCompl;
  78                 int blockLength;
  79                 int cksum_crc;  /* cksum OR crc */
  80                 int expected;
  81                 int i,j;
  82
  83                 blockBegin = read_byte(timeout);
  84                 if (blockBegin < 0)
  85                         goto timeout;
  86
  87                 timeout = TIMEOUT;
  88                 nak = NAK;
  89
  90                 switch (blockBegin) {
  91                 case SOH:
  92                 case STX:
  93                         break;
  94
  95                 case EOT:
  96                         nak = ACK;
  97                         full_write(write_fd, &nak, 1);
  98                         return length;
  99
 100                 default:
 101                         goto error;
 102                 }
 103
 104                 /* block no */
 105                 blockNo = read_byte(TIMEOUT);
 106                 if (blockNo < 0)
 107                         goto timeout;
 108
 109                 /* block no one's compliment */
 110                 blockNoOnesCompl = read_byte(TIMEOUT);
 111                 if (blockNoOnesCompl < 0)
 112                         goto timeout;
 113
 114                 if (blockNo != (255 - blockNoOnesCompl)) {
 115                         bb_error_msg("bad block ones compl");
 116                         goto error;
 117                 }
 118
 119                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 120
 121                 for (i = 0; i < blockLength; i++) {
 122                         int cc = read_byte(TIMEOUT);
 123                         if (cc < 0)
 124                                 goto timeout;
 125                         blockBuf[i] = cc;
 126                 }
 127
 128                 if (do_crc) {
 129                         cksum_crc = read_byte(TIMEOUT);
 130                         if (cksum_crc < 0)
 131                                 goto timeout;
 132                         cksum_crc = (cksum_crc << 8) | read_byte(TIMEOUT);
 133                         if (cksum_crc < 0)
 134                                 goto timeout;
 135                 } else {
 136                         cksum_crc = read_byte(TIMEOUT);
 137                         if (cksum_crc < 0)
 138                                 goto timeout;
 139                 }
 140
 141                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 142                         /* a repeat of the last block is ok, just ignore it. */
 143                         /* this also ignores the initial block 0 which is */
 144                         /* meta data. */
 145                         goto next;
 146                 }
 147                 if (blockNo != (wantBlockNo & 0xff)) {
 148                         bb_error_msg("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 149                         goto error;
 150                 }
 151
 152                 expected = 0;
 153                 if (do_crc) {
 154                         for (i = 0; i < blockLength; i++) {
 155                                 expected = expected ^ blockBuf[i] << 8;
 156                                 for (j = 0; j < 8; j++) {
 157                                         if (expected & 0x8000)
 158                                                 expected = expected << 1 ^ 0x1021;
 159                                         else
 160                                                 expected = expected << 1;
 161                                 }
 162                         }
 163                         expected &= 0xffff;
 164                 } else {
 165                         for (i = 0; i < blockLength; i++)
 166                                 expected += blockBuf[i];
 167                         expected &= 0xff;
 168                 }
 169                 if (cksum_crc != expected) {
 170                         bb_error_msg(do_crc ? "crc error, expected 0x%04x, got 0x%04x"
 171                                            : "checksum error, expected 0x%02x, got 0x%02x",
 172                                             expected, cksum_crc);
 173                         goto error;
 174                 }
 175
 176                 wantBlockNo++;
 177                 length += blockLength;
 178
 179                 errno = 0;
 180                 if (full_write(file_fd, blockBuf, blockLength) != blockLength) {
 181                         bb_perror_msg("can't write to file");
 182                         goto fatal;
 183                 }
 184  next:
 185                 errors = 0;
 186                 nak = ACK;
 187                 full_write(write_fd, &nak, 1);
 188                 continue;
 189  error:
 190  timeout:
 191                 errors++;
 192                 if (errors == MAXERRORS) {
 193                         /* Abort */
 194
 195                         /* if were asking for crc, try again w/o crc */
 196                         if (nak == 'C') {
 197                                 nak = NAK;
 198                                 errors = 0;
 199                                 do_crc = 0;
 200                                 goto timeout;
 201                         }
 202                         bb_error_msg("too many errors; giving up");
 203  fatal:
 204                         /* 5 CAN followed by 5 BS. Don't try too hard... */
 205                         safe_write(write_fd, "\030\030\030\030\030\010\010\010\010\010", 10);
 206                         return -1;
 207                 }
 208
 209                 /* Flush pending input */
 210                 tcflush(read_fd, TCIFLUSH);
 211
 212                 full_write(write_fd, &nak, 1);
 213         } /* for (;;) */
 214 }
 215
 216 static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
 217 {
 218 }
 219
 220 int rx_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 221 int rx_main(int argc, char **argv)
 222 {
 223         struct termios tty, orig_tty;
 224         int termios_err;
 225         int file_fd;
 226         int n;
 227
 228         if (argc != 2)
 229                 bb_show_usage();
 230
 231         /* Disabled by vda:
 232          * why we can't receive from stdin? Why we *require*
 233          * controlling tty?? */
 234         /*read_fd = xopen(CURRENT_TTY, O_RDWR);*/
 235         file_fd = xopen(argv[1], O_RDWR|O_CREAT|O_TRUNC);
 236
 237         termios_err = tcgetattr(read_fd, &tty);
 238         if (termios_err == 0) {
 239                 orig_tty = tty;
 240                 cfmakeraw(&tty);
 241                 tcsetattr(read_fd, TCSAFLUSH, &tty);
 242         }
 243
 244         /* No SA_RESTART: we want ALRM to interrupt read() */
 245         signal_no_SA_RESTART_empty_mask(SIGALRM, sigalrm_handler);
 246
 247         n = receive(file_fd);
 248
 249         if (termios_err == 0)
 250                 tcsetattr(read_fd, TCSAFLUSH, &orig_tty);
 251         if (ENABLE_FEATURE_CLEAN_UP)
 252                 close(file_fd);
 253         fflush_stdout_and_exit(n >= 0);
 254 }