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#include <assert.h>
#include <stdio.h>
#include <string.h>
#include "houdini.h"
#define ESCAPE_GROW_FACTOR(x) (((x) * 12) / 10)
/*
* The following characters will not be escaped:
*
* -_.+!*'(),%#@?=;:/,+&$ alphanum
*
* Note that this character set is the addition of:
*
* - The characters which are safe to be in an URL
* - The characters which are *not* safe to be in
* an URL because they are RESERVED characters.
*
* We asume (lazily) that any RESERVED char that
* appears inside an URL is actually meant to
* have its native function (i.e. as an URL
* component/separator) and hence needs no escaping.
*
* There are two exceptions: the chacters & (amp)
* and ' (single quote) do not appear in the table.
* They are meant to appear in the URL as components,
* yet they require special HTML-entity escaping
* to generate valid HTML markup.
*
* All other characters will be escaped to %XX.
*
*/
static const char HREF_SAFE[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};
void
houdini_escape_href(struct buf *ob, const uint8_t *src, size_t size)
{
static const char hex_chars[] = "0123456789ABCDEF";
size_t i = 0, org;
char hex_str[3];
bufgrow(ob, ESCAPE_GROW_FACTOR(size));
hex_str[0] = '%';
while (i < size) {
org = i;
while (i < size && HREF_SAFE[src[i]] != 0)
i++;
if (i > org)
bufput(ob, src + org, i - org);
/* escaping */
if (i >= size)
break;
switch (src[i]) {
/* amp appears all the time in URLs, but needs
* HTML-entity escaping to be inside an href */
case '&':
BUFPUTSL(ob, "&amp;");
break;
/* the single quote is a valid URL character
* according to the standard; it needs HTML
* entity escaping too */
case '\'':
BUFPUTSL(ob, "&#x27;");
break;
/* the space can be escaped to %20 or a plus
* sign. we're going with the generic escape
* for now. the plus thing is more commonly seen
* when building GET strings */
#if 0
case ' ':
bufputc(ob, '+');
break;
#endif
/* every other character goes with a %XX escaping */
default:
hex_str[1] = hex_chars[(src[i] >> 4) & 0xF];
hex_str[2] = hex_chars[src[i] & 0xF];
bufput(ob, hex_str, 3);
}
i++;
}
}
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