mirror of https://github.com/lianthony/NT4.0
165 lines
3.6 KiB
165 lines
3.6 KiB
/*
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* %Z% %M% %I% %D% %Q%
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*
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* Copyright (C) Microsoft Corporation, 1983
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*
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* This Module contains Proprietary Information of Microsoft
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* Corporation and AT&T, and should be treated as Confidential.
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*/
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/*
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* bencode.c - part of mail
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*
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* Encode/decode binary data in/from printable ascii format.
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*
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* $Revision: 1.1 $ $Date: 85/08/05 18:26:01 $
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*
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* $Log: /u/vich/src/mailer/src/lib/RCS/bencode.c,v $
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* Revision 1.1 85/08/05 18:26:01 vich
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* Initial revision
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*
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*/
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/* only read this file if NOT using uu{en,de}code binary formatting... */
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#if !defined(UUCODE)
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#if defined (NT)
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#error BENCODE.C is not in portable format. Cannot compile this under NT.
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#endif
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/*
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static char rcsid[] = "@(#)bencode.c $Revision: 1.1 $";
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*/
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#include <ctype.h>
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int bencode (char *, char *, int);
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int b6toch(int);
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int chtob6(int);
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int bdecode(char *sp, char *dp, int n);
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int isbencode(int c);
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/*
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* bencode - encode n bytes of a possibly binary character string to use
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* a reasonable character set, copying from the source pointer to the
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* destination pointer. The destination pointer should point to space
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* for (n + (n + 2)/3) bytes, or ((4/3) * n) + 1. Return the number of
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* bytes stored in the destination string. No error is possible.
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*/
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int bencode(sp, dp, n)
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char *sp;
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char *dp;
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int n;
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{
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int c1;
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int c2;
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int c3;
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int cnt = n;
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while (n-- > 0) {
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*dp++ = (char) b6toch(c1 = *sp++);
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if (n-- > 0) {
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*dp++ = (char) b6toch(c2 = *sp++);
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if (n-- > 0) {
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*dp++ = (char) b6toch(c3 = *sp++);
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} else {
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c3 = 0;
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}
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} else {
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c2 = 0;
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}
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cnt++;
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*dp++ = (char) b6toch(((c1 & 0xc0) >> 2) | ((c2 & 0xc0) >> 4) |
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((c3 & 0xc0) >> 6));
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}
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return(cnt);
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}
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/*
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* bdecode - decode n bytes of a binary encoded character string back into
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* a possibly binary character string, copying from the source pointer
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* to the destination pointer. The destination pointer should point to
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* space for (3*n)/4 bytes. Return the number of bytes stored in the
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* destination string. Return -1 on error (unrecognized characters).
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*/
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int bdecode(sp, dp, n)
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char *sp;
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char *dp;
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int n;
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{
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int i;
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int hibits;
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int cnt = n;
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int c;
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while (n >= 2) {
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if ((i = n) > 4) {
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i = 4;
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}
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n -= i;
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if ((hibits = chtob6(sp[--i])) == -1) {
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return(-1);
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}
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while (i--) {
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if ((c = chtob6(*sp++)) == -1) {
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return(-1);
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}
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*dp++ = (char) (((hibits <<= 2) & 0xc0) | c);
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}
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sp++;
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cnt--;
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}
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if (n) {
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return(-1);
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}
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return(cnt);
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}
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/*
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* b6toch - encode a 6 bit binary value into a 64 ascii character set.
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*/
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int b6toch(c)
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int c;
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{
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if ((c &= 0x3f) > (12 + 26 - 1)) {
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c += 'a' - (12 + 26);
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} else if (c > (12 - 1)) {
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c += 'A' - 12;
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} else {
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c += '0';
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}
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return(c);
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}
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/*
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* chtob6 - decode an ascii character into its 6 bit binary equivalent.
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*/
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int chtob6(c)
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int c;
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{
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if (islower(c)) {
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c -= 'a' - (12 + 26);
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} else if (isupper(c)) {
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c -= 'A' - 12;
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} else if ((c -= '0') > 12) {
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c = -1;
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}
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return(c);
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}
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/*
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* isbencode - return true if the passed character is included in the
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* binary encoded character set.
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*/
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int isbencode(c)
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int c;
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{
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return ( ( ( c & 0xff80 ) == 0 && isalnum ( c ) ) || c == ':' ||
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c == ';' );
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}
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#endif /* !defined(UUCODE) */
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