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#include <stdint.h>
#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <iostream>
#include "base32.hh"
using namespace std;
/* based on freebsd:src/contrib/opie/libopie/btoe.c extract: get bit ranges from a char* */
uint32_t extract_bits(const char *s, int start, int length)
{
uint32_t x;
unsigned char cl, cc, cr;
cl = s[start / 8];
cc = s[start / 8 + 1];
cr = s[start / 8 + 2];
x = ((uint32_t) (cl << 8 | cc) << 8 | cr);
x = x >> (24 - (length + (start % 8)));
x = (x & (0xffff >> (16 - length)));
return (x);
}
/* same, set bit ranges in a char* */
static void set_bits(char* s, int x, int start, int length)
{
unsigned char cl, cc, cr;
uint32_t y;
int shift;
shift = ((8 - ((start + length) % 8)) % 8);
y = (uint32_t) x << shift;
cl = (y >> 16) & 0xff;
cc = (y >> 8) & 0xff;
cr = y & 0xff;
if (shift + length > 16) {
s[start / 8] |= cl;
s[start / 8 + 1] |= cc;
s[start / 8 + 2] |= cr;
}
else {
if (shift + length > 8) {
s[start / 8] |= cc;
s[start / 8 + 1] |= cr;
} else {
s[start / 8] |= cr;
}
}
}
/* convert a base32 hex character to its decoded equivalent */
static int unbase32hex(char c)
{
if(c >= '0' && c<='9')
return c-'0';
if(c >= 'a' && c<='z')
return 10 + (c-'a');
if(c >= 'A' && c<='Z')
return 10 + (c-'A');
if(c=='=')
return '=';
return -1;
}
/* convert a binary string to base32hex */
string toBase32Hex(const std::string& input)
{
static const char base32hex[] = "0123456789ABCDEFGHIJKLMNOPQRSTUV=";
string ret;
ret.reserve(4+ 8*input.length()/5); // optimization
// process input in groups of 5 8-bit chunks, emit 8 5-bit chunks
for(string::size_type offset = 0 ; offset < input.length(); offset+=5) {
int todo = input.length() - offset;
int stuffing; // how much '=' to add at the end
switch(todo) {
case 1:
stuffing = 6; break;
case 2:
stuffing = 4; break;
case 3:
stuffing = 3; break;
case 4:
stuffing = 1; break;
default: // -> 0 or more than 5, no stuffing
stuffing = 0; break;
}
for(int n=0; n < 8 - stuffing; ++n)
ret.append(1, base32hex[extract_bits(input.c_str()+offset, n*5, 5)]);
ret.append(stuffing, '=');
}
return ret;
}
// convert base32hex encoded string to normal string
string fromBase32Hex(const std::string& input)
{
string ret;
char block[5]={0,0,0,0,0}; // we process 5 8-bit chunks at a time
string::size_type n, toWrite=0;
for(n = 0; n < input.length(); ++n) {
int c=unbase32hex(input[n]);
if(c == '=' || c < 0) // stop at stuffing or error
break;
set_bits(block, c , (n % 8) * 5, 5);
if(++toWrite == 8) {
ret.append(block, sizeof(block));
memset(block, 0, sizeof(block));
toWrite = 0;
}
}
ret.append(block, (7+toWrite*5)/8); // round up
return ret;
}
#if 0
int main(int argc, char **argv)
{
if(argc!=3 || (argc==3 && strcmp(argv[1],"from") && strcmp(argv[1],"to"))) {
printf("syntax: base32 from|to string\n");
exit(0);
}
if(!strcmp(argv[1],"to")) {
printf("input: '%s'\noutput: '%s'\n",
argv[2],
toBase32Hex(argv[2]).c_str());
}
else {
cout<<"input: '"<<argv[2]<<"'\noutput: '"<<fromBase32Hex(argv[2])<<"'\n";
}
}
#endif
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