282 lines
6.3 KiB
C
282 lines
6.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Copyright: Copyright (C) 2001, Hewlett-Packard Company
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* Author: Christopher Hoover <ch@hpl.hp.com>
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* Description: xmodem functionality for uploading of kernels
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* and the like
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* Created at: Thu Dec 20 01:58:08 PST 2001
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*
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* xmodem functionality for uploading of kernels and the like
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*
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* Copyright (C) 2001 Hewlett-Packard Laboratories
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*
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* This was originally written for blob and then adapted for busybox.
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*/
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//config:config RX
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//config: bool "rx"
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//config: default y
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//config: select PLATFORM_LINUX
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//config: help
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//config: Receive files using the Xmodem protocol.
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//applet:IF_RX(APPLET(rx, BB_DIR_USR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_RX) += rx.o
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//usage:#define rx_trivial_usage
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//usage: "FILE"
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//usage:#define rx_full_usage "\n\n"
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//usage: "Receive a file using the xmodem protocol"
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//usage:
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//usage:#define rx_example_usage
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//usage: "$ rx /tmp/foo\n"
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#include "libbb.h"
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#define SOH 0x01
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#define STX 0x02
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#define EOT 0x04
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#define ACK 0x06
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#define NAK 0x15
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#define BS 0x08
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#define PAD 0x1A
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/*
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Cf:
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http://www.textfiles.com/apple/xmodem
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http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
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http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
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http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
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*/
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#define TIMEOUT 1
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#define TIMEOUT_LONG 10
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#define MAXERRORS 10
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#define read_fd STDIN_FILENO
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#define write_fd STDOUT_FILENO
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static int read_byte(unsigned timeout)
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{
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unsigned char buf;
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int n;
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alarm(timeout);
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/* NOT safe_read! We want ALRM to interrupt us */
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n = read(read_fd, &buf, 1);
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alarm(0);
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if (n == 1)
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return buf;
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return -1;
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}
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static int receive(/*int read_fd, */int file_fd)
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{
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unsigned char blockBuf[1024];
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unsigned blockLength = 0;
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unsigned errors = 0;
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unsigned wantBlockNo = 1;
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unsigned length = 0;
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int do_crc = 1;
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char reply_char;
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unsigned timeout = TIMEOUT_LONG;
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/* Flush pending input */
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tcflush(read_fd, TCIFLUSH);
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/* Ask for CRC; if we get errors, we will go with checksum */
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reply_char = 'C';
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full_write(write_fd, &reply_char, 1);
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for (;;) {
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int blockBegin;
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int blockNo, blockNoOnesCompl;
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int cksum_or_crc;
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int expected;
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int i, j;
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blockBegin = read_byte(timeout);
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if (blockBegin < 0)
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goto timeout;
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/* If last block, remove padding */
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if (blockBegin == EOT) {
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/* Data blocks can be padded with ^Z characters */
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/* This code tries to detect and remove them */
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if (blockLength >= 3
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&& blockBuf[blockLength - 1] == PAD
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&& blockBuf[blockLength - 2] == PAD
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&& blockBuf[blockLength - 3] == PAD
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) {
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while (blockLength
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&& blockBuf[blockLength - 1] == PAD
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) {
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blockLength--;
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}
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}
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}
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/* Write previously received block */
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errno = 0;
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if (full_write(file_fd, blockBuf, blockLength) != blockLength) {
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bb_perror_msg(bb_msg_write_error);
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goto fatal;
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}
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timeout = TIMEOUT;
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reply_char = NAK;
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switch (blockBegin) {
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case SOH:
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case STX:
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break;
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case EOT:
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reply_char = ACK;
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full_write(write_fd, &reply_char, 1);
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return length;
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default:
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goto error;
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}
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/* Block no */
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blockNo = read_byte(TIMEOUT);
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if (blockNo < 0)
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goto timeout;
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/* Block no, in one's complement form */
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blockNoOnesCompl = read_byte(TIMEOUT);
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if (blockNoOnesCompl < 0)
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goto timeout;
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if (blockNo != (255 - blockNoOnesCompl)) {
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bb_error_msg("bad block ones compl");
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goto error;
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}
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blockLength = (blockBegin == SOH) ? 128 : 1024;
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for (i = 0; i < blockLength; i++) {
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int cc = read_byte(TIMEOUT);
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if (cc < 0)
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goto timeout;
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blockBuf[i] = cc;
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}
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cksum_or_crc = read_byte(TIMEOUT);
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if (cksum_or_crc < 0)
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goto timeout;
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if (do_crc) {
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cksum_or_crc = (cksum_or_crc << 8) | read_byte(TIMEOUT);
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if (cksum_or_crc < 0)
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goto timeout;
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}
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if (blockNo == ((wantBlockNo - 1) & 0xff)) {
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/* a repeat of the last block is ok, just ignore it. */
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/* this also ignores the initial block 0 which is */
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/* meta data. */
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blockLength = 0;
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goto next;
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}
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if (blockNo != (wantBlockNo & 0xff)) {
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bb_error_msg("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
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goto error;
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}
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expected = 0;
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if (do_crc) {
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for (i = 0; i < blockLength; i++) {
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expected = expected ^ blockBuf[i] << 8;
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for (j = 0; j < 8; j++) {
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if (expected & 0x8000)
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expected = (expected << 1) ^ 0x1021;
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else
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expected = (expected << 1);
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}
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}
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expected &= 0xffff;
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} else {
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for (i = 0; i < blockLength; i++)
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expected += blockBuf[i];
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expected &= 0xff;
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}
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if (cksum_or_crc != expected) {
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bb_error_msg(do_crc ? "crc error, expected 0x%04x, got 0x%04x"
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: "checksum error, expected 0x%02x, got 0x%02x",
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expected, cksum_or_crc);
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goto error;
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}
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wantBlockNo++;
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length += blockLength;
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next:
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errors = 0;
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reply_char = ACK;
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full_write(write_fd, &reply_char, 1);
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continue;
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error:
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timeout:
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blockLength = 0;
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errors++;
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if (errors == MAXERRORS) {
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/* Abort */
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/* If were asking for crc, try again w/o crc */
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if (reply_char == 'C') {
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reply_char = NAK;
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errors = 0;
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do_crc = 0;
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goto timeout;
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}
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bb_error_msg("too many errors; giving up");
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fatal:
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/* 5 CAN followed by 5 BS. Don't try too hard... */
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safe_write(write_fd, "\030\030\030\030\030\010\010\010\010\010", 10);
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return -1;
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}
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/* Flush pending input */
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tcflush(read_fd, TCIFLUSH);
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full_write(write_fd, &reply_char, 1);
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} /* for (;;) */
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}
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static void sigalrm_handler(int UNUSED_PARAM signum)
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{
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}
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int rx_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int rx_main(int argc UNUSED_PARAM, char **argv)
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{
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struct termios tty, orig_tty;
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int termios_err;
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int file_fd;
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int n;
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/* Disabled by vda:
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* why we can't receive from stdin? Why we *require*
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* controlling tty?? */
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/*read_fd = xopen(CURRENT_TTY, O_RDWR);*/
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file_fd = xopen(single_argv(argv), O_RDWR|O_CREAT|O_TRUNC);
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termios_err = tcgetattr(read_fd, &tty);
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if (termios_err == 0) {
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orig_tty = tty;
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cfmakeraw(&tty);
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tcsetattr(read_fd, TCSAFLUSH, &tty);
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}
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/* No SA_RESTART: we want ALRM to interrupt read() */
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signal_no_SA_RESTART_empty_mask(SIGALRM, sigalrm_handler);
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n = receive(file_fd);
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if (termios_err == 0)
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tcsetattr(read_fd, TCSAFLUSH, &orig_tty);
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if (ENABLE_FEATURE_CLEAN_UP)
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close(file_fd);
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fflush_stdout_and_exit(n >= 0);
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}
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