util.c

#include "main.h"

static uint8_t hex[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

static void to_hex(uint8_t *a, uint8_t *p, int size)
{
    uint8_t b, *end = p + size;

    while(p != end) {
        b = *p++;

        *a++ = hex[b >> 4];
        *a++ = hex[b & 0xF];
    }
}

void key_to_string(uint8_t *dest, uint8_t *src)
{
    to_hex(dest, src, 32);
}

void id_to_string(uint8_t *dest, uint8_t *src)
{
    to_hex(dest, src, TOX_ID_SIZE);
}

_Bool string_to_id(uint8_t *w, uint8_t *a)
{
    uint8_t *end = w + TOX_ID_SIZE;
    while(w != end) {
        uint8_t c, v;

        c = *a++;
        if(c >= '0' && c <= '9') {
            v = (c - '0') << 4;
        } else if(c >= 'A' && c <= 'F') {
            v = (c - 'A' + 10) << 4;
        } else {
            return 0;
        }

        c = *a++;
        if(c >= '0' && c <= '9') {
            v |= (c - '0');
        } else if(c >= 'A' && c <= 'F') {
            v |= (c - 'A' + 10);
        } else {
            return 0;
        }

        *w++ = v;
    }

    return 1;
}

_Bool validate_id(uint8_t *id)
{
    uint8_t checksum[2] = {0};
    uint32_t i;

    for (i = 0; i < 36; ++i)
        checksum[i % 2] ^= id[i];

    return (id[36] == checksum[0] && id[37] == checksum[1]);
}