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 "busybox.h"
  24 #include <stdlib.h>
  25 #include <stdarg.h>
  26 #include <stdio.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <termios.h>
  30 #include <signal.h>
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <fcntl.h>
  34 #include <string.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 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 int read_byte(int fd, unsigned int timeout) {
  60         char buf[1];
  61         int n;
  62
  63         alarm(timeout);
  64
  65         n = read(fd, &buf, 1);
  66
  67         alarm(0);
  68
  69         if (n == 1)
  70                 return buf[0] & 0xff;
  71         else
  72                 return -1;
  73 }
  74
  75 static int receive(char *error_buf, size_t error_buf_size,
  76                                    int ttyfd, int filefd)
  77 {
  78         char blockBuf[1024];
  79         unsigned int errors = 0;
  80         unsigned int wantBlockNo = 1;
  81         unsigned int length = 0;
  82         int docrc = 1;
  83         char nak = 'C';
  84         unsigned int timeout = TIMEOUT_LONG;
  85
  86 #define note_error(fmt,args...) \
  87         snprintf(error_buf, error_buf_size, fmt,##args)
  88
  89         /* Flush pending input */
  90         tcflush(ttyfd, TCIFLUSH);
  91
  92         /* Ask for CRC; if we get errors, we will go with checksum */
  93         write(ttyfd, &nak, 1);
  94
  95         for (;;) {
  96                 int blockBegin;
  97                 int blockNo, blockNoOnesCompl;
  98                 int blockLength;
  99                 int cksum = 0;
 100                 int crcHi = 0;
 101                 int crcLo = 0;
 102
 103                 blockBegin = read_byte(ttyfd, timeout);
 104                 if (blockBegin < 0)
 105                         goto timeout;
 106
 107                 timeout = TIMEOUT;
 108                 nak = NAK;
 109
 110                 switch (blockBegin) {
 111                 case SOH:
 112                 case STX:
 113                         break;
 114
 115                 case EOT:
 116                         nak = ACK;
 117                         write(ttyfd, &nak, 1);
 118                         goto done;
 119
 120                 default:
 121                         goto error;
 122                 }
 123
 124                 /* block no */
 125                 blockNo = read_byte(ttyfd, TIMEOUT);
 126                 if (blockNo < 0)
 127                         goto timeout;
 128
 129                 /* block no one's compliment */
 130                 blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
 131                 if (blockNoOnesCompl < 0)
 132                         goto timeout;
 133
 134                 if (blockNo != (255 - blockNoOnesCompl)) {
 135                         note_error("bad block ones compl");
 136                         goto error;
 137                 }
 138
 139                 blockLength = (blockBegin == SOH) ? 128 : 1024;
 140
 141                 {
 142                         int i;
 143
 144                         for (i = 0; i < blockLength; i++) {
 145                                 int cc = read_byte(ttyfd, TIMEOUT);
 146                                 if (cc < 0)
 147                                         goto timeout;
 148                                 blockBuf[i] = cc;
 149                         }
 150                 }
 151
 152                 if (docrc) {
 153                         crcHi = read_byte(ttyfd, TIMEOUT);
 154                         if (crcHi < 0)
 155                                 goto timeout;
 156
 157                         crcLo = read_byte(ttyfd, TIMEOUT);
 158                         if (crcLo < 0)
 159                                 goto timeout;
 160                 } else {
 161                         cksum = read_byte(ttyfd, TIMEOUT);
 162                         if (cksum < 0)
 163                                 goto timeout;
 164                 }
 165
 166                 if (blockNo == ((wantBlockNo - 1) & 0xff)) {
 167                         /* a repeat of the last block is ok, just ignore it. */
 168                         /* this also ignores the initial block 0 which is */
 169                         /* meta data. */
 170                         goto next;
 171                 } else if (blockNo != (wantBlockNo & 0xff)) {
 172                         note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
 173                         goto error;
 174                 }
 175
 176                 if (docrc) {
 177                         int crc = 0;
 178                         int i, j;
 179                         int expectedCrcHi;
 180                         int expectedCrcLo;
 181
 182                         for (i = 0; i < blockLength; i++) {
 183                                 crc = crc ^ (int) blockBuf[i] << 8;
 184                                 for (j = 0; j < 8; j++)
 185                                         if (crc & 0x8000)
 186                                                 crc = crc << 1 ^ 0x1021;
 187                                         else
 188                                                 crc = crc << 1;
 189                         }
 190
 191                         expectedCrcHi = (crc >> 8) & 0xff;
 192                         expectedCrcLo = crc & 0xff;
 193
 194                         if ((crcHi != expectedCrcHi) ||
 195                             (crcLo != expectedCrcLo)) {
 196                                 note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
 197                                 goto error;
 198                         }
 199                 } else {
 200                         unsigned char expectedCksum = 0;
 201                         int i;
 202
 203                         for (i = 0; i < blockLength; i++)
 204                                 expectedCksum += blockBuf[i];
 205
 206                         if (cksum != expectedCksum) {
 207                                 note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
 208                                 goto error;
 209                         }
 210                 }
 211
 212                 wantBlockNo++;
 213                 length += blockLength;
 214
 215                 if (full_write(filefd, blockBuf, blockLength) < 0) {
 216                         note_error("write to file failed: %m");
 217                         goto fatal;
 218                 }
 219
 220         next:
 221                 errors = 0;
 222                 nak = ACK;
 223                 write(ttyfd, &nak, 1);
 224                 continue;
 225
 226         error:
 227         timeout:
 228                 errors++;
 229                 if (errors == MAXERRORS) {
 230                         /* Abort */
 231
 232                         // if using crc, try again w/o crc
 233                         if (nak == 'C') {
 234                                 nak = NAK;
 235                                 errors = 0;
 236                                 docrc = 0;
 237                                 goto timeout;
 238                         }
 239
 240                         note_error("too many errors; giving up");
 241
 242                 fatal:
 243                         /* 5 CAN followed by 5 BS */
 244                         write(ttyfd, "\030\030\030\030\030\010\010\010\010\010", 10);
 245                         return -1;
 246                 }
 247
 248                 /* Flush pending input */
 249                 tcflush(ttyfd, TCIFLUSH);
 250
 251                 write(ttyfd, &nak, 1);
 252         }
 253
 254  done:
 255         return length;
 256
 257 #undef note_error
 258 }
 259
 260 static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
 261 {
 262 }
 263
 264 int rx_main(int argc, char **argv)
 265 {
 266         char *fn;
 267         int ttyfd, filefd;
 268         struct termios tty, orig_tty;
 269         struct sigaction act;
 270         int n;
 271         char error_buf[256];
 272
 273         if (argc != 2)
 274                         bb_show_usage();
 275
 276         fn = argv[1];
 277         ttyfd = bb_xopen3(CURRENT_TTY, O_RDWR, 0);
 278         filefd = bb_xopen3(fn, O_RDWR|O_CREAT|O_TRUNC, 0666);
 279
 280         if (tcgetattr(ttyfd, &tty) < 0)
 281                         bb_error_msg_and_die("%s: tcgetattr failed: %m\n", argv[0]);
 282
 283         orig_tty = tty;
 284
 285         cfmakeraw(&tty);
 286         tcsetattr(ttyfd, TCSAFLUSH, &tty);
 287
 288         memset(&act, 0, sizeof(act));
 289         act.sa_handler = sigalrm_handler;
 290         sigaction(SIGALRM, &act, 0);
 291
 292         n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
 293
 294         close(filefd);
 295
 296         tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
 297
 298         if (n < 0)
 299                         bb_error_msg_and_die("\n%s: receive failed:\n  %s\n",
 300                                                            argv[0], error_buf);
 301
 302         bb_fflush_stdout_and_exit(EXIT_SUCCESS);
 303 }