hex2bin.c

unsigned char* hex2bin(const char* hexstr, size_t* size)
{
    size_t hexstrLen = strlen(hexstr);
    size_t bytesLen = hexstrLen / 2;

    unsigned char* bytes = (unsigned char*) malloc(bytesLen);

    int count = 0;
    const char* pos = hexstr;

    for(count = 0; count < bytesLen; count++) {
        sscanf(pos, "%2hhx", &bytes[count]);
        pos += 2;
    }

    if( size != NULL )
        *size = bytesLen;

    return bytes;
}