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autolink.c
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autolink.c
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/*
* Copyright (c) 2011, Vicent Marti
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "buffer.h"
#include "autolink.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#if defined(_WIN32)
#define strncasecmp _strnicmp
#endif
int
sd_autolink_issafe(const uint8_t *link, size_t link_len)
{
static const size_t valid_uris_count = 5;
static const char *valid_uris[] = {
"/", "http://", "https://", "ftp://", "mailto:"
};
size_t i;
for (i = 0; i < valid_uris_count; ++i) {
size_t len = strlen(valid_uris[i]);
if (link_len > len &&
strncasecmp((char *)link, valid_uris[i], len) == 0 &&
isalnum(link[len]))
return 1;
}
return 0;
}
static size_t
autolink_delim(uint8_t *data, size_t link_end, size_t max_rewind, size_t size)
{
uint8_t cclose, copen = 0;
size_t i;
for (i = 0; i < link_end; ++i)
if (data[i] == '<') {
link_end = i;
break;
}
while (link_end > 0) {
if (strchr("?!.,", data[link_end - 1]) != NULL)
link_end--;
else if (data[link_end - 1] == ';') {
size_t new_end = link_end - 2;
while (new_end > 0 && isalpha(data[new_end]))
new_end--;
if (new_end < link_end - 2 && data[new_end] == '&')
link_end = new_end;
else
link_end--;
}
else break;
}
if (link_end == 0)
return 0;
cclose = data[link_end - 1];
switch (cclose) {
case '"': copen = '"'; break;
case '\'': copen = '\''; break;
case ')': copen = '('; break;
case ']': copen = '['; break;
case '}': copen = '{'; break;
}
if (copen != 0) {
size_t closing = 0;
size_t opening = 0;
size_t i = 0;
/* Try to close the final punctuation sign in this same line;
* if we managed to close it outside of the URL, that means that it's
* not part of the URL. If it closes inside the URL, that means it
* is part of the URL.
*
* Examples:
*
* foo http://www.pokemon.com/Pikachu_(Electric) bar
* => http://www.pokemon.com/Pikachu_(Electric)
*
* foo (http://www.pokemon.com/Pikachu_(Electric)) bar
* => http://www.pokemon.com/Pikachu_(Electric)
*
* foo http://www.pokemon.com/Pikachu_(Electric)) bar
* => http://www.pokemon.com/Pikachu_(Electric))
*
* (foo http://www.pokemon.com/Pikachu_(Electric)) bar
* => foo http://www.pokemon.com/Pikachu_(Electric)
*/
while (i < link_end) {
if (data[i] == copen)
opening++;
else if (data[i] == cclose)
closing++;
i++;
}
if (closing != opening)
link_end--;
}
return link_end;
}
static size_t
check_domain(uint8_t *data, size_t size, int allow_short)
{
size_t i, np = 0;
if (!isalnum(data[0]))
return 0;
for (i = 1; i < size - 1; ++i) {
if (data[i] == '.') np++;
else if (!isalnum(data[i]) && data[i] != '-') break;
}
if (allow_short) {
/* We don't need a valid domain in the strict sense (with
* least one dot; so just make sure it's composed of valid
* domain characters and return the length of the the valid
* sequence. */
return i;
} else {
/* a valid domain needs to have at least a dot.
* that's as far as we get */
return np ? i : 0;
}
}
size_t
sd_autolink__www(
size_t *rewind_p,
struct buf *link,
uint8_t *data,
size_t max_rewind,
size_t size,
unsigned int flags)
{
size_t link_end;
if (max_rewind > 0 && !ispunct(data[-1]) && !isspace(data[-1]))
return 0;
if (size < 4 || memcmp(data, "www.", strlen("www.")) != 0)
return 0;
link_end = check_domain(data, size, 0);
if (link_end == 0)
return 0;
while (link_end < size && !isspace(data[link_end]))
link_end++;
link_end = autolink_delim(data, link_end, max_rewind, size);
if (link_end == 0)
return 0;
bufput(link, data, link_end);
*rewind_p = 0;
return (int)link_end;
}
size_t
sd_autolink__email(
size_t *rewind_p,
struct buf *link,
uint8_t *data,
size_t max_rewind,
size_t size,
unsigned int flags)
{
size_t link_end, rewind;
int nb = 0, np = 0;
for (rewind = 0; rewind < max_rewind; ++rewind) {
uint8_t c = data[-rewind - 1];
if (isalnum(c))
continue;
if (strchr(".+-_", c) != NULL)
continue;
break;
}
if (rewind == 0)
return 0;
for (link_end = 0; link_end < size; ++link_end) {
uint8_t c = data[link_end];
if (isalnum(c))
continue;
if (c == '@')
nb++;
else if (c == '.' && link_end < size - 1)
np++;
else if (c != '-' && c != '_')
break;
}
if (link_end < 2 || nb != 1 || np == 0 ||
!isalpha(data[link_end - 1]))
return 0;
link_end = autolink_delim(data, link_end, max_rewind, size);
if (link_end == 0)
return 0;
bufput(link, data - rewind, link_end + rewind);
*rewind_p = rewind;
return link_end;
}
size_t
sd_autolink__url(
size_t *rewind_p,
struct buf *link,
uint8_t *data,
size_t max_rewind,
size_t size,
unsigned int flags)
{
size_t link_end, rewind = 0, domain_len;
if (size < 4 || data[1] != '/' || data[2] != '/')
return 0;
while (rewind < max_rewind && isalpha(data[-rewind - 1]))
rewind++;
if (!sd_autolink_issafe(data - rewind, size + rewind))
return 0;
link_end = strlen("://");
domain_len = check_domain(
data + link_end,
size - link_end,
flags & SD_AUTOLINK_SHORT_DOMAINS);
if (domain_len == 0)
return 0;
link_end += domain_len;
while (link_end < size && !isspace(data[link_end]))
link_end++;
link_end = autolink_delim(data, link_end, max_rewind, size);
if (link_end == 0)
return 0;
bufput(link, data - rewind, link_end + rewind);
*rewind_p = rewind;
return link_end;
}