[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Copyright: Copyright (C) 2001, Hewlett-Packard Company
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| 4 | * Author: Christopher Hoover <ch@hpl.hp.com>
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| 5 | * Description: xmodem functionality for uploading of kernels
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| 6 | * and the like
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| 7 | * Created at: Thu Dec 20 01:58:08 PST 2001
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| 8 | *
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| 9 | * xmodem functionality for uploading of kernels and the like
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| 10 | *
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| 11 | * Copyright (C) 2001 Hewlett-Packard Laboratories
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| 12 | *
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| 13 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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| 14 | *
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| 15 | * This was originally written for blob and then adapted for busybox.
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| 16 | */
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| 17 |
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| 18 | #include "libbb.h"
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| 19 |
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| 20 | #define SOH 0x01
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| 21 | #define STX 0x02
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| 22 | #define EOT 0x04
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| 23 | #define ACK 0x06
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| 24 | #define NAK 0x15
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| 25 | #define BS 0x08
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| 26 | #define PAD 0x1A
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| 27 |
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| 28 | /*
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| 29 | Cf:
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| 30 | http://www.textfiles.com/apple/xmodem
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| 31 | http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
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| 32 | http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
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| 33 | http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
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| 34 | */
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| 35 |
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| 36 | #define TIMEOUT 1
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| 37 | #define TIMEOUT_LONG 10
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| 38 | #define MAXERRORS 10
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| 39 |
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| 40 | #define read_fd STDIN_FILENO
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| 41 | #define write_fd STDOUT_FILENO
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| 42 |
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| 43 | static int read_byte(unsigned timeout)
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| 44 | {
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| 45 | unsigned char buf;
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| 46 | int n;
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| 47 |
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| 48 | alarm(timeout);
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| 49 | /* NOT safe_read! We want ALRM to interrupt us */
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| 50 | n = read(read_fd, &buf, 1);
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| 51 | alarm(0);
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| 52 | if (n == 1)
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| 53 | return buf;
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| 54 | return -1;
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| 55 | }
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| 56 |
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| 57 | static int receive(/*int read_fd, */int file_fd)
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| 58 | {
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| 59 | unsigned char blockBuf[1024];
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| 60 | unsigned blockLength = 0;
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| 61 | unsigned errors = 0;
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| 62 | unsigned wantBlockNo = 1;
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| 63 | unsigned length = 0;
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| 64 | int do_crc = 1;
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| 65 | char reply_char;
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| 66 | unsigned timeout = TIMEOUT_LONG;
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| 67 |
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| 68 | /* Flush pending input */
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| 69 | tcflush(read_fd, TCIFLUSH);
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| 70 |
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| 71 | /* Ask for CRC; if we get errors, we will go with checksum */
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| 72 | reply_char = 'C';
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| 73 | full_write(write_fd, &reply_char, 1);
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| 74 |
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| 75 | for (;;) {
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| 76 | int blockBegin;
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| 77 | int blockNo, blockNoOnesCompl;
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| 78 | int cksum_or_crc;
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| 79 | int expected;
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| 80 | int i, j;
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| 81 |
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| 82 | blockBegin = read_byte(timeout);
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| 83 | if (blockBegin < 0)
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| 84 | goto timeout;
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| 85 |
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| 86 | /* If last block, remove padding */
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| 87 | if (blockBegin == EOT) {
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| 88 | /* Data blocks can be padded with ^Z characters */
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| 89 | /* This code tries to detect and remove them */
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| 90 | if (blockLength >= 3
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| 91 | && blockBuf[blockLength - 1] == PAD
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| 92 | && blockBuf[blockLength - 2] == PAD
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| 93 | && blockBuf[blockLength - 3] == PAD
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| 94 | ) {
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| 95 | while (blockLength
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| 96 | && blockBuf[blockLength - 1] == PAD
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| 97 | ) {
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| 98 | blockLength--;
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| 99 | }
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| 100 | }
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| 101 | }
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| 102 | /* Write previously received block */
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| 103 | if (blockLength) {
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| 104 | errno = 0;
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| 105 | if (full_write(file_fd, blockBuf, blockLength) != blockLength) {
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| 106 | bb_perror_msg("can't write to file");
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| 107 | goto fatal;
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| 108 | }
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| 109 | }
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| 110 |
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| 111 | timeout = TIMEOUT;
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| 112 | reply_char = NAK;
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| 113 |
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| 114 | switch (blockBegin) {
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| 115 | case SOH:
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| 116 | case STX:
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| 117 | break;
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| 118 | case EOT:
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| 119 | reply_char = ACK;
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| 120 | full_write(write_fd, &reply_char, 1);
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| 121 | return length;
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| 122 | default:
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| 123 | goto error;
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| 124 | }
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| 125 |
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| 126 | /* Block no */
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| 127 | blockNo = read_byte(TIMEOUT);
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| 128 | if (blockNo < 0)
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| 129 | goto timeout;
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| 130 |
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| 131 | /* Block no, in one's complement form */
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| 132 | blockNoOnesCompl = read_byte(TIMEOUT);
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| 133 | if (blockNoOnesCompl < 0)
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| 134 | goto timeout;
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| 135 |
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| 136 | if (blockNo != (255 - blockNoOnesCompl)) {
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| 137 | bb_error_msg("bad block ones compl");
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| 138 | goto error;
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| 139 | }
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| 140 |
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| 141 | blockLength = (blockBegin == SOH) ? 128 : 1024;
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| 142 |
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| 143 | for (i = 0; i < blockLength; i++) {
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| 144 | int cc = read_byte(TIMEOUT);
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| 145 | if (cc < 0)
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| 146 | goto timeout;
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| 147 | blockBuf[i] = cc;
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| 148 | }
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| 149 |
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| 150 | if (do_crc) {
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| 151 | cksum_or_crc = read_byte(TIMEOUT);
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| 152 | if (cksum_or_crc < 0)
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| 153 | goto timeout;
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| 154 | cksum_or_crc = (cksum_or_crc << 8) | read_byte(TIMEOUT);
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| 155 | if (cksum_or_crc < 0)
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| 156 | goto timeout;
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| 157 | } else {
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| 158 | cksum_or_crc = read_byte(TIMEOUT);
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| 159 | if (cksum_or_crc < 0)
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| 160 | goto timeout;
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| 161 | }
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| 162 |
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| 163 | if (blockNo == ((wantBlockNo - 1) & 0xff)) {
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| 164 | /* a repeat of the last block is ok, just ignore it. */
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| 165 | /* this also ignores the initial block 0 which is */
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| 166 | /* meta data. */
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| 167 | goto next;
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| 168 | }
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| 169 | if (blockNo != (wantBlockNo & 0xff)) {
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| 170 | bb_error_msg("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
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| 171 | goto error;
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| 172 | }
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| 173 |
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| 174 | expected = 0;
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| 175 | if (do_crc) {
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| 176 | for (i = 0; i < blockLength; i++) {
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| 177 | expected = expected ^ blockBuf[i] << 8;
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| 178 | for (j = 0; j < 8; j++) {
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| 179 | if (expected & 0x8000)
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| 180 | expected = (expected << 1) ^ 0x1021;
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| 181 | else
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| 182 | expected = (expected << 1);
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| 183 | }
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| 184 | }
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| 185 | expected &= 0xffff;
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| 186 | } else {
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| 187 | for (i = 0; i < blockLength; i++)
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| 188 | expected += blockBuf[i];
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| 189 | expected &= 0xff;
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| 190 | }
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| 191 | if (cksum_or_crc != expected) {
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| 192 | bb_error_msg(do_crc ? "crc error, expected 0x%04x, got 0x%04x"
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| 193 | : "checksum error, expected 0x%02x, got 0x%02x",
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| 194 | expected, cksum_or_crc);
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| 195 | goto error;
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| 196 | }
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| 197 |
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| 198 | wantBlockNo++;
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| 199 | length += blockLength;
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| 200 | next:
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| 201 | errors = 0;
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| 202 | reply_char = ACK;
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| 203 | full_write(write_fd, &reply_char, 1);
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| 204 | continue;
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| 205 | error:
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| 206 | timeout:
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| 207 | errors++;
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| 208 | if (errors == MAXERRORS) {
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| 209 | /* Abort */
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| 210 |
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| 211 | /* If were asking for crc, try again w/o crc */
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| 212 | if (reply_char == 'C') {
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| 213 | reply_char = NAK;
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| 214 | errors = 0;
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| 215 | do_crc = 0;
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| 216 | goto timeout;
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| 217 | }
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| 218 | bb_error_msg("too many errors; giving up");
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| 219 | fatal:
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| 220 | /* 5 CAN followed by 5 BS. Don't try too hard... */
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| 221 | safe_write(write_fd, "\030\030\030\030\030\010\010\010\010\010", 10);
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| 222 | return -1;
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| 223 | }
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| 224 |
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| 225 | /* Flush pending input */
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| 226 | tcflush(read_fd, TCIFLUSH);
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| 227 |
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| 228 | full_write(write_fd, &reply_char, 1);
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| 229 | } /* for (;;) */
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| 230 | }
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| 231 |
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| 232 | static void sigalrm_handler(int UNUSED_PARAM signum)
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| 233 | {
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| 234 | }
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| 235 |
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| 236 | int rx_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 237 | int rx_main(int argc UNUSED_PARAM, char **argv)
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| 238 | {
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| 239 | struct termios tty, orig_tty;
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| 240 | int termios_err;
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| 241 | int file_fd;
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| 242 | int n;
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| 243 |
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| 244 | /* Disabled by vda:
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| 245 | * why we can't receive from stdin? Why we *require*
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| 246 | * controlling tty?? */
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| 247 | /*read_fd = xopen(CURRENT_TTY, O_RDWR);*/
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| 248 | file_fd = xopen(single_argv(argv), O_RDWR|O_CREAT|O_TRUNC);
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| 249 |
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| 250 | termios_err = tcgetattr(read_fd, &tty);
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| 251 | if (termios_err == 0) {
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| 252 | orig_tty = tty;
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| 253 | cfmakeraw(&tty);
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| 254 | tcsetattr(read_fd, TCSAFLUSH, &tty);
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| 255 | }
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| 256 |
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| 257 | /* No SA_RESTART: we want ALRM to interrupt read() */
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| 258 | signal_no_SA_RESTART_empty_mask(SIGALRM, sigalrm_handler);
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| 259 |
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| 260 | n = receive(file_fd);
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| 261 |
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| 262 | if (termios_err == 0)
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| 263 | tcsetattr(read_fd, TCSAFLUSH, &orig_tty);
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| 264 | if (ENABLE_FEATURE_CLEAN_UP)
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| 265 | close(file_fd);
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| 266 | fflush_stdout_and_exit(n >= 0);
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| 267 | }
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