128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
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/*-
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* Copyright (c) 2006 M. Warner Losh. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This software is derived from software provide by Kwikbyte who specifically
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* disclaimed copyright on the code. This version of xmodem has been nearly
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* completely rewritten, but the CRC is from the original.
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*
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* $FreeBSD$
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*/
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#include "lib.h"
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#define PACKET_SIZE 128
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/* Line control codes */
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#define SOH 0x01 /* start of header */
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#define ACK 0x06 /* Acknowledge */
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#define NAK 0x15 /* Negative acknowledge */
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#define CAN 0x18 /* Cancel */
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#define EOT 0x04 /* end of text */
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/*
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* int GetRecord(char , char *)
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* This private function receives a x-modem record to the pointer and
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* returns non-zero on success.
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*/
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static int
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GetRecord(char blocknum, char *dest)
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{
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int size;
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int ch;
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unsigned chk, j;
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chk = 0;
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if ((ch = getc(1)) == -1)
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goto err;
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if (ch != blocknum)
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goto err;
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if ((ch = getc(1)) == -1)
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goto err;
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if (ch != (~blocknum & 0xff))
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goto err;
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for (size = 0; size < PACKET_SIZE; ++size) {
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if ((ch = getc(1)) == -1)
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goto err;
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chk = chk ^ ch << 8;
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for (j = 0; j < 8; ++j) {
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if (chk & 0x8000)
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chk = chk << 1 ^ 0x1021;
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else
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chk = chk << 1;
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}
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*dest++ = ch;
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}
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chk &= 0xFFFF;
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if (((ch = getc(1)) == -1) || ((ch & 0xff) != ((chk >> 8) & 0xFF)))
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goto err;
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if (((ch = getc(1)) == -1) || ((ch & 0xff) != (chk & 0xFF)))
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goto err;
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putc(ACK);
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return (1);
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err:;
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putc(CAN);
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// We should allow for resend, but we don't.
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return (0);
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}
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/*
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* int xmodem_rx(char *)
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* This global function receives a x-modem transmission consisting of
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* (potentially) several blocks. Returns the number of bytes received or
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* -1 on error.
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*/
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int
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xmodem_rx(char *dest)
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{
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int starting, ch;
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char packetNumber, *startAddress = dest;
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packetNumber = 1;
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starting = 1;
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while (1) {
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if (starting)
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putc('C');
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if (((ch = getc(1)) == -1) || (ch != SOH && ch != EOT))
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continue;
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if (ch == EOT) {
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putc(ACK);
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return (dest - startAddress);
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}
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starting = 0;
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// Xmodem packets: SOH PKT# ~PKT# 128-bytes CRC16
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if (!GetRecord(packetNumber, dest))
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return (-1);
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dest += PACKET_SIZE;
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packetNumber++;
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}
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// the loop above should return in all cases
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return (-1);
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}
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