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#include "escape.h"
#include <assert.h>
#include <stdio.h>
#include <string.h>
#define likely(x) __builtin_expect((x),1)
#define unlikely(x) __builtin_expect((x),0)
/*
* 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 assume (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 uint8_t HREF_SAFE[UINT8_MAX+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, 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
hoedown_escape_href(hoedown_buffer *ob, const uint8_t *data, size_t size)
{
static const char hex_chars[] = "0123456789ABCDEF";
size_t i = 0, mark;
char hex_str[3];
hex_str[0] = '%';
while (i < size) {
mark = i;
while (i < size && HREF_SAFE[data[i]]) i++;
/* Optimization for cases where there's nothing to escape */
if (mark == 0 && i >= size) {
hoedown_buffer_put(ob, data, size);
return;
}
if (likely(i > mark)) {
hoedown_buffer_put(ob, data + mark, i - mark);
}
/* escaping */
if (i >= size)
break;
switch (data[i]) {
/* amp appears all the time in URLs, but needs
* HTML-entity escaping to be inside an href */
case '&':
HOEDOWN_BUFPUTSL(ob, "&");
break;
/* the single quote is a valid URL character
* according to the standard; it needs HTML
* entity escaping too */
case '\'':
HOEDOWN_BUFPUTSL(ob, "'");
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 ' ':
hoedown_buffer_putc(ob, '+');
break;
#endif
/* every other character goes with a %XX escaping */
default:
hex_str[1] = hex_chars[(data[i] >> 4) & 0xF];
hex_str[2] = hex_chars[data[i] & 0xF];
hoedown_buffer_put(ob, (uint8_t *)hex_str, 3);
}
i++;
}
}
/**
* According to the OWASP rules:
*
* & --> &
* < --> <
* > --> >
* " --> "
* ' --> ' ' is not recommended
* / --> / forward slash is included as it helps end an HTML entity
*
*/
static const uint8_t HTML_ESCAPE_TABLE[UINT8_MAX+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, 1, 0, 0, 0, 2, 3, 0, 0, 0, 0, 0, 0, 0, 4,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 6, 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, 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,
};
static const char *HTML_ESCAPES[] = {
"",
""",
"&",
"'",
"/",
"<",
">"
};
void
hoedown_escape_html(hoedown_buffer *ob, const uint8_t *data, size_t size, int secure)
{
size_t i = 0, mark;
while (1) {
mark = i;
while (i < size && HTML_ESCAPE_TABLE[data[i]] == 0) i++;
/* Optimization for cases where there's nothing to escape */
if (mark == 0 && i >= size) {
hoedown_buffer_put(ob, data, size);
return;
}
if (likely(i > mark))
hoedown_buffer_put(ob, data + mark, i - mark);
if (i >= size) break;
/* The forward slash is only escaped in secure mode */
if (!secure && data[i] == '/') {
hoedown_buffer_putc(ob, '/');
} else {
hoedown_buffer_puts(ob, HTML_ESCAPES[HTML_ESCAPE_TABLE[data[i]]]);
}
i++;
}
}
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