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// SPDX-License-Identifier: GPL-3.0-or-later
#include "../libnetdata.h"
// ----------------------------------------------------------------------------
// URL encode / decode
// code from: http://www.geekhideout.com/urlcode.shtml
/* Converts a hex character to its integer value */
char from_hex(char ch) {
return (char)(isdigit(ch) ? ch - '0' : tolower(ch) - 'a' + 10);
}
/* Converts an integer value to its hex character*/
char to_hex(char code) {
static char hex[] = "0123456789abcdef";
return hex[code & 15];
}
/* Returns a url-encoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_encode(char *str) {
char *buf, *pbuf;
pbuf = buf = mallocz(strlen(str) * 3 + 1);
while (*str) {
if (isalnum(*str) || *str == '-' || *str == '_' || *str == '.' || *str == '~')
*pbuf++ = *str;
else if (*str == ' ')
*pbuf++ = '+';
else
*pbuf++ = '%', *pbuf++ = to_hex(*str >> 4), *pbuf++ = to_hex(*str & 15);
str++;
}
*pbuf = '\0';
pbuf = strdupz(buf);
freez(buf);
return pbuf;
}
/* Returns a url-decoded version of str */
/* IMPORTANT: be sure to free() the returned string after use */
char *url_decode(char *str) {
size_t size = strlen(str) + 1;
char *buf = mallocz(size);
return url_decode_r(buf, str, size);
}
//decode %XX character or return 0 if cannot
char url_percent_escape_decode(char *s) {
if(likely(s[1] && s[2]))
return from_hex(s[1]) << 4 | from_hex(s[2]);
return 0;
}
//this (utf8 string related) should be moved in separate file in future
char url_utf8_get_byte_length(char c) {
if(!IS_UTF8_BYTE(c))
return 1;
char length = 0;
while(likely(c & 0x80)) {
length++;
c <<= 1;
}
//4 byte is max size for UTF-8 char
//10XX XXXX is not valid character -> check length == 1
if(length > 4 || length == 1)
return -1;
return length;
}
//decode % encoded UTF-8 characters and copy them to *d
//return count of bytes written to *d
char url_decode_multibyte_utf8(char *s, char *d, char *d_end) {
char first_byte = url_percent_escape_decode(s);
if(unlikely(!first_byte || !IS_UTF8_STARTBYTE(first_byte)))
return 0;
char byte_length = url_utf8_get_byte_length(first_byte);
if(unlikely(byte_length <= 0 || d+byte_length >= d_end))
return 0;
char to_read = byte_length;
while(to_read > 0) {
char c = url_percent_escape_decode(s);
if(unlikely( !IS_UTF8_BYTE(c) ))
return 0;
if((to_read != byte_length) && IS_UTF8_STARTBYTE(c))
return 0;
*d++ = c;
s+=3;
to_read--;
}
return byte_length;
}
/*
* The utf8_check() function scans the '\0'-terminated string starting
* at s. It returns a pointer to the first byte of the first malformed
* or overlong UTF-8 sequence found, or NULL if the string contains
* only correct UTF-8. It also spots UTF-8 sequences that could cause
* trouble if converted to UTF-16, namely surrogate characters
* (U+D800..U+DFFF) and non-Unicode positions (U+FFFE..U+FFFF). This
* routine is very likely to find a malformed sequence if the input
* uses any other encoding than UTF-8. It therefore can be used as a
* very effective heuristic for distinguishing between UTF-8 and other
* encodings.
*
* Markus Kuhn <http://www.cl.cam.ac.uk/~mgk25/> -- 2005-03-30
* License: http://www.cl.cam.ac.uk/~mgk25/short-license.html
*/
unsigned char *utf8_check(unsigned char *s)
{
while (*s)
{
if (*s < 0x80)
/* 0xxxxxxx */
s++;
else if ((s[0] & 0xe0) == 0xc0)
{
/* 110XXXXx 10xxxxxx */
if ((s[1] & 0xc0) != 0x80 ||
(s[0] & 0xfe) == 0xc0) /* overlong? */
return s;
else
s += 2;
}
else if ((s[0] & 0xf0) == 0xe0)
{
/* 1110XXXX 10Xxxxxx 10xxxxxx */
if ((s[1] & 0xc0) != 0x80 ||
(s[2] & 0xc0) != 0x80 ||
(s[0] == 0xe0 && (s[1] & 0xe0) == 0x80) || /* overlong? */
(s[0] == 0xed && (s[1] & 0xe0) == 0xa0) || /* surrogate? */
(s[0] == 0xef && s[1] == 0xbf &&
(s[2] & 0xfe) == 0xbe)) /* U+FFFE or U+FFFF? */
return s;
else
s += 3;
}
else if ((s[0] & 0xf8) == 0xf0)
{
/* 11110XXX 10XXxxxx 10xxxxxx 10xxxxxx */
if ((s[1] & 0xc0) != 0x80 ||
(s[2] & 0xc0) != 0x80 ||
(s[3] & 0xc0) != 0x80 ||
(s[0] == 0xf0 && (s[1] & 0xf0) == 0x80) || /* overlong? */
(s[0] == 0xf4 && s[1] > 0x8f) || s[0] > 0xf4) /* > U+10FFFF? */
return s;
else
s += 4;
}
else
return s;
}
return NULL;
}
char *url_decode_r(char *to, char *url, size_t size) {
char *s = url, // source
*d = to, // destination
*e = &to[size - 1]; // destination end
while(*s && d < e) {
if(unlikely(*s == '%')) {
char t = url_percent_escape_decode(s);
if(IS_UTF8_BYTE(t)) {
char bytes_written = url_decode_multibyte_utf8(s, d, e);
if(likely(bytes_written)){
d += bytes_written;
s += (bytes_written * 3)-1;
}
else {
goto fail_cleanup;
}
}
else if(likely(t) && isprint(t)) {
// avoid HTTP header injection
*d++ = t;
s += 2;
}
else
goto fail_cleanup;
}
else if(unlikely(*s == '+'))
*d++ = ' ';
else
*d++ = *s;
s++;
}
*d = '\0';
if(unlikely( utf8_check(to) )) //NULL means sucess here
return NULL;
return to;
fail_cleanup:
*d = '\0';
return NULL;
}
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