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/* hex.c - conversion for hexadecimal and base32 strings.
*
* Copyright: 2008-2012 Aleksey Kravchenko <rhash.admin@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. Use this program at your own risk!
*/
#include <string.h>
#include <ctype.h>
#include "hex.h"
/**
* Convert a byte to a hexadecimal number. The result, consisting of two
* hexadecimal digits is stored into a buffer.
*
* @param dest the buffer to receive two symbols of hex representation
* @param byte the byte to decode
* @param upper_case flag to print string in uppercase
* @return pointer to the chararcter just after the written number (dest + 2)
*/
char* rhash_print_hex_byte(char *dest, const unsigned char byte, int upper_case)
{
const char add = (upper_case ? 'A' - 10 : 'a' - 10);
unsigned char c = (byte >> 4) & 15;
*dest++ = (c > 9 ? c + add : c + '0');
c = byte & 15;
*dest++ = (c > 9 ? c + add : c + '0');
return dest;
}
/**
* Store hexadecimal representation of a binary string to given buffer.
*
* @param dest the buffer to receive hexadecimal representation
* @param src binary string
* @param len string length
* @param upper_case flag to print string in uppercase
*/
void rhash_byte_to_hex(char *dest, const unsigned char *src, unsigned len, int upper_case)
{
while (len-- > 0) {
dest = rhash_print_hex_byte(dest, *src++, upper_case);
}
*dest = '\0';
}
/**
* Encode a binary string to base32.
*
* @param dest the buffer to store result
* @param src binary string
* @param len string length
* @param upper_case flag to print string in uppercase
*/
void rhash_byte_to_base32(char* dest, const unsigned char* src, unsigned len, int upper_case)
{
const char a = (upper_case ? 'A' : 'a');
unsigned shift = 0;
unsigned char word;
const unsigned char* e = src + len;
while (src < e) {
if (shift > 3) {
word = (*src & (0xFF >> shift));
shift = (shift + 5) % 8;
word <<= shift;
if (src + 1 < e)
word |= *(src + 1) >> (8 - shift);
++src;
} else {
shift = (shift + 5) % 8;
word = ( *src >> ( (8 - shift) & 7 ) ) & 0x1F;
if (shift == 0) src++;
}
*dest++ = ( word < 26 ? word + a : word + '2' - 26 );
}
*dest = '\0';
}
/**
* Encode a binary string to base64.
* Encoded output length is always a multiple of 4 bytes.
*
* @param dest the buffer to store result
* @param src binary string
* @param len string length
*/
void rhash_byte_to_base64(char* dest, const unsigned char* src, unsigned len)
{
static const char* tail = "0123456789+/";
unsigned shift = 0;
unsigned char word;
const unsigned char* e = src + len;
while (src < e) {
if (shift > 2) {
word = (*src & (0xFF >> shift));
shift = (shift + 6) % 8;
word <<= shift;
if (src + 1 < e)
word |= *(src + 1) >> (8 - shift);
++src;
} else {
shift = (shift + 6) % 8;
word = ( *src >> ( (8 - shift) & 7 ) ) & 0x3F;
if (shift == 0) src++;
}
*dest++ = ( word < 52 ? (word < 26 ? word + 'A' : word - 26 + 'a') : tail[word - 52]);
}
if (shift > 0) {
*dest++ = '=';
if (shift == 4) *dest++ = '=';
}
*dest = '\0';
}
/* unsafe characters are "<>{}[]%#/|\^~`@:;?=&+ */
#define IS_GOOD_URL_CHAR(c) (isalnum((unsigned char)c) || strchr("$-_.!'(),", c))
/**
* URL-encode a string.
*
* @param dst buffer to receive result or NULL to calculate
* the lengths of encoded string
* @param filename the file name
* @return the length of the result string
*/
int rhash_urlencode(char *dst, const char *name)
{
const char *start;
if (!dst) {
int len;
for (len = 0; *name; name++) len += (IS_GOOD_URL_CHAR(*name) ? 1 : 3);
return len;
}
/* encode URL as specified by RFC 1738 */
for (start = dst; *name; name++) {
if ( IS_GOOD_URL_CHAR(*name) ) {
*dst++ = *name;
} else {
*dst++ = '%';
dst = rhash_print_hex_byte(dst, *name, 'A');
}
}
*dst = 0;
return (int)(dst - start);
}
/**
* Print 64-bit number with trailing '\0' to a string buffer.
* if dst is NULL, then just return the length of the number.
*
* @param dst output buffer
* @param number the number to print
* @return length of the printed number (without trailing '\0')
*/
int rhash_sprintI64(char *dst, uint64_t number)
{
/* The biggest number has 20 digits: 2^64 = 18 446 744 073 709 551 616 */
char buf[24], *p;
size_t length;
if (dst == NULL) {
/* just calculate the length of the number */
if (number == 0) return 1;
for (length = 0; number != 0; number /= 10) length++;
return (int)length;
}
p = buf + 23;
*p = '\0'; /* last symbol should be '\0' */
if (number == 0) {
*(--p) = '0';
} else {
for (; p >= buf && number != 0; number /= 10) {
*(--p) = '0' + (char)(number % 10);
}
}
length = buf + 23 - p;
memcpy(dst, p, length + 1);
return (int)length;
}
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