mirror of
https://github.com/yarrick/iodine.git
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339 lines
6.9 KiB
C
339 lines
6.9 KiB
C
/*
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* Copyright (c) 2006-2008 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "encoding.h"
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#include "common.h"
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#include "base64.h"
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static const char cb64[] =
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"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-0123456789.";
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static unsigned char rev64[128];
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static int reverse_init = 0;
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#define REV64(x) rev64[(int) (x)]
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#define MODE (cb64[62])
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#define P62 (cb64[62])
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#define P63 (cb64[63])
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static struct encoder base64_encoder =
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{
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"BASE64",
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base64_encode,
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base64_decode,
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base64_handles_dots,
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base64_handles_dots
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};
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struct encoder
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*get_base64_encoder()
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{
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return &base64_encoder;
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}
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int
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base64_handles_dots()
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{
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return 0;
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}
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static void
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findesc(int *count, unsigned char *esc, char c1, char c2, char c3, char c4)
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{
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int min1 = 0;
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int min2 = 0;
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int num1 = 0xFF; /* a very big number */
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int num2 = 0xFE; /* a nearly as big number */
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int i;
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/* check if no more escapes needed */
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if (count[62] == 0 && count[63] == 0) {
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esc[0] = MODE;
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esc[1] = MODE;
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return;
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}
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for (i = 0; i < 62; i++) {
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if (i == c1 || i == c2 || i == c3 || i == c4) {
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continue;
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}
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if (count[i] < num1) {
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min2 = min1;
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num2 = num1;
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min1 = i;
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num1 = count[i];
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} else if (count[i] < num2) {
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min2 = i;
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num2 = count[i];
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}
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}
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esc[0] = cb64[min1];
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esc[1] = cb64[min2];
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}
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static void
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escape_chars(char *buf, size_t buflen)
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{
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int counter[64];
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int escapes;
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int reset;
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int i;
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unsigned char temp[4096];
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unsigned char *r;
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unsigned char *w;
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unsigned char *e;
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unsigned char esc[2];
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memset(counter, 0, sizeof(counter));
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esc[0] = P62;
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esc[1] = P63;
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/* first, find the number of times each token is used */
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r = (unsigned char *) buf;
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w = temp;
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while (*r) {
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counter[REV64(*r)]++;
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*w++ = *r++;
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}
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/* check if work needed */
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if (counter[62] == 0 && counter[63] == 0)
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return;
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r = temp;
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w = (unsigned char *) buf;
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reset = 1;
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escapes = 0;
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/* check a block for esc chars */
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while (*r) {
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if (reset == 0 && escapes == 0 && (
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r[0] == esc[0] || r[1] == esc[0] ||r[2] == esc[0] ||r[2] == esc[0] ||
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r[0] == esc[1] || r[1] == esc[1] ||r[2] == esc[1] ||r[2] == esc[1])) {
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/* last set of escape chars were unused.
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* if we reset last escape switch then maybe we dont have to switch now */
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/* change the latest escape switch to 999 (RESET) */
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e[1] = MODE;
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e[2] = MODE;
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/* store default esc chars */
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esc[0] = P62;
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esc[1] = P63;
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reset = 1;
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}
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/* these two if blocks can not be combined because a block can contain both
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* char 9 and/or . and the current escape chars. */
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if (r[0] == esc[0] || r[1] == esc[0] ||r[2] == esc[0] ||r[2] == esc[0] ||
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r[0] == esc[1] || r[1] == esc[1] ||r[2] == esc[1] ||r[2] == esc[1]) {
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/* switch escape chars */
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escapes = 0;
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reset = 0;
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/* find 2 suitable escape chars */
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findesc(counter, esc, REV64(r[0]), REV64(r[1]), REV64(r[2]), REV64(r[3]));
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/* store escape switch position */
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e = w;
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/* write new escape chars */
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*w++ = MODE;
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*w++ = esc[0];
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*w++ = esc[1];
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}
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/* update counter on remaining chars */
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for (i = 0; i < 4; i++) {
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if (r[i])
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counter[REV64(r[i])]--;
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}
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/* do the escaping */
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for (i = 0; i < 4; i++) {
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if (r[i] == P62) {
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r[i] = esc[0];
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escapes++;
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} else if (r[i] == P63) {
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r[i] = esc[1];
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escapes++;
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}
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}
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/* copy back to buf */
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*w++ = *r++;
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*w++ = *r++;
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*w++ = *r++;
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*w++ = *r++;
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}
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}
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int
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base64_encode(char *buf, size_t *buflen, const void *data, size_t size)
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{
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size_t newsize;
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size_t maxsize;
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unsigned char c;
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unsigned char *s;
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unsigned char *p;
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unsigned char *q;
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int i;
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memset(buf, 0, *buflen);
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if (!reverse_init) {
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for (i = 0; i < 64; i++) {
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c = cb64[i];
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rev64[(int) c] = i;
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}
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reverse_init = 1;
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}
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/* how many chars can we encode within the buf */
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maxsize = 3 * (*buflen / 4 - 1) - 1;
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/* how big will the encoded data be */
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newsize = 4 * (size / 3 + 1) + 1;
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/* if the buffer is too small, eat some of the data */
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if (*buflen < newsize) {
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size = maxsize;
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}
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p = s = (unsigned char *) buf;
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q = (unsigned char *)data;
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for(i=0;i<size;i+=3) {
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p[0] = cb64[((q[0] & 0xfc) >> 2)];
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p[1] = cb64[(((q[0] & 0x03) << 4) | ((q[1] & 0xf0) >> 4))];
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p[2] = (i+1 < size) ? cb64[((q[1] & 0x0f) << 2 ) | ((q[2] & 0xc0) >> 6)] : '\0';
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p[3] = (i+2 < size) ? cb64[(q[2] & 0x3f)] : '\0';
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q += 3;
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p += 4;
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}
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*p = 0;
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escape_chars(buf, *buflen);
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/* store number of bytes from data that was used */
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*buflen = size;
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return strlen(buf) - 1;
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}
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#define DECODE_ERROR 0xffffffff
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static int
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decode_token(const unsigned char *t, unsigned char *data, size_t len)
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{
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if (len < 2)
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return 0;
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data[0] = ((REV64(t[0]) & 0x3f) << 2) |
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((REV64(t[1]) & 0x30) >> 4);
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if (len < 3)
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return 1;
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data[1] = ((REV64(t[1]) & 0x0f) << 4) |
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((REV64(t[2]) & 0x3c) >> 2);
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if (len < 4)
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return 2;
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data[2] = ((REV64(t[2]) & 0x03) << 6) |
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(REV64(t[3]) & 0x3f);
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return 3;
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}
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int
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base64_decode(void *buf, size_t *buflen, const char *str, size_t slen)
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{
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unsigned char *q;
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size_t newsize;
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size_t maxsize;
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const char *p;
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unsigned char c;
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unsigned char block[4];
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unsigned char prot62;
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unsigned char prot63;
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int len;
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int i;
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if (!reverse_init) {
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for (i = 0; i < 64; i++) {
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c = cb64[i];
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rev64[(int) c] = i;
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}
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reverse_init = 1;
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}
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/* chars needed to decode slen */
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newsize = 3 * (slen / 4 + 1) + 1;
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/* encoded chars that fit in buf */
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maxsize = 4 * (*buflen / 3 + 1) + 1;
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/* if the buffer is too small, eat some of the data */
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if (*buflen < newsize) {
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slen = maxsize;
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}
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prot62 = P62;
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prot63 = P63;
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q = buf;
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for (p = str; *p; p += 4) {
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/* handle escape instructions */
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if (*p == MODE) {
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p++;
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if (p[0] == MODE && p[1] == MODE) {
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/* reset escape chars */
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prot62 = P62;
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prot63 = P63;
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p += 2;
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} else {
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prot62 = *p++;
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prot63 = *p++;
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}
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}
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/* since the str is const, we unescape in another buf */
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for (i = 0; i < 4; i++) {
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block[i] = p[i];
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if (prot62 == block[i]) {
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block[i] = P62;
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} else if (prot63 == block[i]) {
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block[i] = P63;
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}
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}
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len = decode_token(block, (unsigned char *) q, slen);
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q += len;
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slen -= 4;
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if (len < 3)
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break;
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}
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*q = '\0';
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return q - (unsigned char *) buf;
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}
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