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119 lines
2.6 KiB
C
119 lines
2.6 KiB
C
/*
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* File: base64.c
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* Description: Simple BASE64 conversion methods
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* Author: Ari Edelkind
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* License: Public Domain
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* Website: http://episec.com/people/edelkind/c.html
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*/
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#include <string.h>
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char b64string[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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long base64_encode (to, from, len)
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char *to, *from;
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unsigned int len;
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{
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char *fromp = from;
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char *top = to;
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unsigned char cbyte;
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unsigned char obyte;
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char end[3];
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for (; len >= 3; len -= 3) {
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cbyte = *fromp++;
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*top++ = b64string[(int)(cbyte >> 2)];
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obyte = (cbyte << 4) & 0x30; /* 0011 0000 */
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cbyte = *fromp++;
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obyte |= (cbyte >> 4); /* 0000 1111 */
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*top++ = b64string[(int)obyte];
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obyte = (cbyte << 2) & 0x3C; /* 0011 1100 */
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cbyte = *fromp++;
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obyte |= (cbyte >> 6); /* 0000 0011 */
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*top++ = b64string[(int)obyte];
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*top++ = b64string[(int)(cbyte & 0x3F)];/* 0011 1111 */
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}
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if (len) {
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end[0] = *fromp++;
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if (--len) end[1] = *fromp++; else end[1] = 0;
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end[2] = 0;
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cbyte = end[0];
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*top++ = b64string[(int)(cbyte >> 2)];
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obyte = (cbyte << 4) & 0x30; /* 0011 0000 */
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cbyte = end[1];
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obyte |= (cbyte >> 4);
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*top++ = b64string[(int)obyte];
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obyte = (cbyte << 2) & 0x3C; /* 0011 1100 */
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if (len) *top++ = b64string[(int)obyte];
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else *top++ = '=';
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*top++ = '=';
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}
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*top = 0;
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return top - to;
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}
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/* badchar(): check if c is decent; puts either the */
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/* location of c or null into p. */
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#define badchar(c,p) (!(p = memchr(b64string, c, 64)))
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long base64_decode (to, from, len)
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char *to, *from;
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unsigned int len;
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{
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char *fromp = from;
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char *top = to;
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char *p;
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unsigned char cbyte;
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unsigned char obyte;
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int padding = 0;
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for (; len >= 4; len -= 4) {
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if ((cbyte = *fromp++) == '=') cbyte = 0;
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else {
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if (badchar(cbyte, p)) return -1;
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cbyte = (p - b64string);
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}
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obyte = cbyte << 2; /* 1111 1100 */
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if ((cbyte = *fromp++) == '=') cbyte = 0;
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else {
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if (badchar(cbyte, p)) return -1;
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cbyte = p - b64string;
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}
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obyte |= cbyte >> 4; /* 0000 0011 */
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*top++ = obyte;
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obyte = cbyte << 4; /* 1111 0000 */
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if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
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else {
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padding = 0;
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if (badchar (cbyte, p)) return -1;
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cbyte = p - b64string;
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}
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obyte |= cbyte >> 2; /* 0000 1111 */
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*top++ = obyte;
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obyte = cbyte << 6; /* 1100 0000 */
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if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
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else {
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padding = 0;
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if (badchar (cbyte, p)) return -1;
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cbyte = p - b64string;
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}
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obyte |= cbyte; /* 0011 1111 */
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*top++ = obyte;
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}
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*top = 0;
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if (len) return -1;
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return (top - to) - padding;
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}
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