knx/examples/knx-linux/fdsk.cpp
2024-08-09 21:30:35 +02:00

195 lines
4.0 KiB
C++

#include "fdsk.h"
#include <string.h>
// CRC-4 generator polynom: 10011 (x^4+x+1)
const uint8_t FdskCalculator::crc4_tab[16] =
{
0x0, 0x3, 0x6, 0x5, 0xc, 0xf, 0xa, 0x9,
0xb, 0x8, 0xd, 0xe, 0x7, 0x4, 0x1, 0x2
};
int FdskCalculator::snprintFdsk(char* str, int strSize, uint8_t* serialNumber, uint8_t* key)
{
char* tmpStr = generateFdskString(serialNumber, key);
int written = 0;
for (int i = 0; i < 36; i++)
{
if (((i % 6) == 0) && (i!=0))
{
*(str+written++) = '-';
if (written >= strSize-1)
break;
}
*(str+written++) = tmpStr[i];
if (written >= strSize-1)
break;
}
*(str+written++) = '\0';
delete[] tmpStr;
return written;
}
char* FdskCalculator::generateFdskString(uint8_t* serialNumber, uint8_t* key)
{
uint8_t buffer[6 + 16 + 1]; // 6 bytes serialnumber + 16 bytes key + 1 byte placeholder for crc-4
memcpy(&buffer[0], serialNumber, 6);
memcpy(&buffer[6], key, 16);
buffer[22] = (crc4Array(buffer, sizeof(buffer)-1)<<4) &0xFF;
uint8_t* outEncoded = nullptr;
toBase32(buffer, sizeof(buffer), outEncoded, false);
return (char*)outEncoded;
}
int FdskCalculator::ceil(float num)
{
int inum = (int)num;
if (num == (float)inum) {
return inum;
}
return inum + 1;
}
int FdskCalculator::toBase32(uint8_t* in, long length, uint8_t*& out, bool usePadding)
{
char base32StandardAlphabet[] = {"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"};
char standardPaddingChar = '=';
int result = 0;
int index = 0;
int size = 0; // size of temporary array
uint8_t* temp = nullptr;
if (length < 0 || length > 268435456LL)
{
return 0;
}
size = 8 * ceil(length / 4.0); // Calculating size of temporary array. Not very precise.
temp = new uint8_t[size];
if (length > 0)
{
int buffer = in[0];
int next = 1;
int bitsLeft = 8;
while (bitsLeft > 0 || next < length)
{
if (bitsLeft < 5)
{
if (next < length)
{
buffer <<= 8;
buffer |= in[next] & 0xFF;
next++;
bitsLeft += 8;
}
else
{
int pad = 5 - bitsLeft;
buffer <<= pad;
bitsLeft += pad;
}
}
index = 0x1F & (buffer >> (bitsLeft -5));
bitsLeft -= 5;
temp[result] = (uint8_t)base32StandardAlphabet[index];
result++;
}
}
if (usePadding)
{
int pads = (result % 8);
if (pads > 0)
{
pads = (8 - pads);
for (int i = 0; i < pads; i++)
{
temp[result] = standardPaddingChar;
result++;
}
}
}
out = new uint8_t[result];
memcpy(out, temp, result);
delete [] temp;
return result;
}
int FdskCalculator::fromBase32(uint8_t* in, long length, uint8_t*& out)
{
int result = 0; // Length of the array of decoded values.
int buffer = 0;
int bitsLeft = 0;
uint8_t* temp = NULL;
temp = new uint8_t[length]; // Allocating temporary array.
for (int i = 0; i < length; i++)
{
uint8_t ch = in[i];
// ignoring some characters: ' ', '\t', '\r', '\n', '='
if (ch == 0xA0 || ch == 0x09 || ch == 0x0A || ch == 0x0D || ch == 0x3D)
continue;
// recovering mistyped: '0' -> 'O', '1' -> 'L', '8' -> 'B'
if (ch == 0x30)
{
ch = 0x4F;
}
else if (ch == 0x31)
{
ch = 0x4C;
}
else if (ch == 0x38)
{
ch = 0x42;
}
// look up one base32 symbols: from 'A' to 'Z' or from 'a' to 'z' or from '2' to '7'
if ((ch >= 0x41 && ch <= 0x5A) || (ch >= 0x61 && ch <= 0x7A))
{
ch = ((ch & 0x1F) - 1);
}
else if (ch >= 0x32 && ch <= 0x37)
{
ch -= (0x32 - 26);
}
else {
delete [] temp;
return 0;
}
buffer <<= 5;
buffer |= ch;
bitsLeft += 5;
if (bitsLeft >= 8)
{
temp[result] = (unsigned char)((unsigned int)(buffer >> (bitsLeft - 8)) & 0xFF);
result++;
bitsLeft -= 8;
}
}
out = new uint8_t[result];
memcpy(out, temp, result);
delete [] temp;
return result;
}