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/* hex.c - conversion for hexadecimal and base32 strings.
*
* Copyright (c) 2008, Aleksey Kravchenko <rhash.admin@gmail.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* 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 "hex.h"
#include <assert.h>
#include <ctype.h>
#include <string.h>
/**
* Store hexadecimal representation of a binary string to given buffer.
*
* @param dst the buffer to receive hexadecimal representation
* @param src binary string
* @param length string length
* @param upper_case flag to print string in uppercase
*/
void rhash_byte_to_hex(char* dst, const unsigned char* src, size_t length, int upper_case)
{
const char hex_add = (upper_case ? 'A' - 10 : 'a' - 10);
for (; length > 0; src++, length--) {
const unsigned char hi = (*src >> 4) & 15;
const unsigned char lo = *src & 15;
*dst++ = (hi > 9 ? hi + hex_add : hi + '0');
*dst++ = (lo > 9 ? lo + hex_add : lo + '0');
}
*dst = '\0';
}
/**
* Encode a binary string to base32.
*
* @param dst the buffer to store result
* @param src binary string
* @param length string length
* @param upper_case flag to print string in uppercase
*/
void rhash_byte_to_base32(char* dst, const unsigned char* src, size_t length, int upper_case)
{
const char a = (upper_case ? 'A' : 'a');
unsigned shift = 0;
unsigned char word;
const unsigned char* e = src + length;
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++;
}
*dst++ = ( word < 26 ? word + a : word + '2' - 26 );
}
*dst = '\0';
}
/**
* Encode a binary string to base64.
* Encoded output length is always a multiple of 4 bytes.
*
* @param dst the buffer to store result
* @param src binary string
* @param length string length
*/
void rhash_byte_to_base64(char* dst, const unsigned char* src, size_t length)
{
static const char* tail = "0123456789+/";
unsigned shift = 0;
unsigned char word;
const unsigned char* e = src + length;
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++;
}
*dst++ = ( word < 52 ? (word < 26 ? word + 'A' : word - 26 + 'a') : tail[word - 52]);
}
if (shift > 0) {
*dst++ = '=';
if (shift == 4) *dst++ = '=';
}
*dst = '\0';
}
size_t rhash_base64_url_encoded_helper(char* dst, const unsigned char* src, size_t length, int url_encode, int upper_case)
{
#define B64_CHUNK_SIZE 120
char buffer[164];
#ifdef __clang_analyzer__
memset(buffer, 0, sizeof(buffer));
#endif
assert((BASE64_LENGTH(B64_CHUNK_SIZE) + 4) <= sizeof(buffer));
assert((B64_CHUNK_SIZE % 6) == 0);
if (url_encode) {
size_t result_length = 0;
for (; length > 0; src += B64_CHUNK_SIZE) {
size_t chunk_size = (length < B64_CHUNK_SIZE ? length : B64_CHUNK_SIZE);
size_t encoded_length;
rhash_byte_to_base64(buffer, src, chunk_size);
encoded_length = rhash_urlencode(dst, buffer, BASE64_LENGTH(chunk_size), upper_case);
result_length += encoded_length;
dst += encoded_length;
length -= chunk_size;
}
return result_length;
}
rhash_byte_to_base64(dst, src, length);
return BASE64_LENGTH(length);
}
/* RFC 3986: safe url characters are ascii alpha-numeric and "-._~", other characters should be percent-encoded */
static unsigned url_safe_char_mask[4] = { 0, 0x03ff6000, 0x87fffffe, 0x47fffffe };
#define IS_URL_GOOD_CHAR(c) ((unsigned)(c) < 128 && (url_safe_char_mask[c >> 5] & (1 << (c & 31))))
/**
* URL-encode specified binary string.
*
* @param dst (nullable) buffer to output encoded string to,
* NULL to just calculate the lengths of encoded string
* @param src binary string to encode
* @param size size of the binary string
* @param upper_case flag to output hex-codes in uppercase
* @return the length of the result string
*/
size_t rhash_urlencode(char* dst, const char* src, size_t size, int upper_case)
{
const char* start;
size_t i;
if (!dst) {
size_t length = size;
for (i = 0; i < size; i++)
if (!IS_URL_GOOD_CHAR(src[i]))
length += 2;
return length;
} else {
const char hex_add = (upper_case ? 'A' - 10 : 'a' - 10);
start = dst;
/* percent-encode all but unreserved URL characters */
for (i = 0; i < size; i++) {
if (IS_URL_GOOD_CHAR(src[i])) {
*dst++ = src[i];
} else {
unsigned char hi = ((unsigned char)(src[i]) >> 4) & 0x0f;
unsigned char lo = (unsigned char)(src[i]) & 0x0f;
*dst++ = '%';
*dst++ = (hi > 9 ? hi + hex_add : hi + '0');
*dst++ = (lo > 9 ? lo + hex_add : lo + '0');
}
}
*dst = 0;
}
return 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];
char* 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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