cryb-to/lib/enc/cryb_percent_decode.c

79 lines
2.5 KiB
C

/*-
* Copyright (c) 2014-2016 Dag-Erling Smørgrav
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "cryb/impl.h"
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <cryb/ctype.h>
#include <cryb/rfc3986.h>
#define unhex(ch) \
((ch >= '0' && ch <= '9') ? ch - '0' : \
(ch >= 'A' && ch <= 'F') ? 0xa + ch - 'A' : \
(ch >= 'a' && ch <= 'f') ? 0xa + ch - 'a' : 0)
/*
* Decodes a string in RFC 3986 percent-encoded representation.
*/
int
percent_decode(const char *in, size_t ilen, char *out, size_t *olen)
{
size_t len;
for (len = 0; ilen > 0 && *in != '\0'; --ilen, ++in) {
if (*in != '%') {
if (++len < *olen && out != NULL)
*out++ = *in;
} else if (ilen >= 3 && is_xdigit(in[1]) && is_xdigit(in[2])) {
if (++len < *olen && out != NULL)
*out++ = unhex(in[1]) << 4 | unhex(in[2]);
in += 2;
ilen -= 2;
} else {
if (*olen > 0 && out != NULL)
*out = '\0';
*olen = ++len;
errno = EINVAL;
return (-1);
}
}
if (*olen > 0 && out != NULL)
*out = '\0';
if (++len > *olen && out != NULL) {
/* overflow */
*olen = len;
errno = ENOSPC;
return (-1);
}
*olen = len;
return (0);
}