/*
 * This file is part of RTRlib.
 *
 * This file is subject to the terms and conditions of the MIT license.
 * See the file LICENSE in the top level directory for more details.
 *
 * Website: http://rtrlib.realmv6.org/
*/

#include "rtrlib/lib/ipv6.h"
#include "rtrlib/lib/ipv4.h"
#include "rtrlib/lib/utils.h"
#include <arpa/inet.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>

inline bool lrtr_ipv6_addr_equal(const struct lrtr_ipv6_addr *a, const struct lrtr_ipv6_addr *b)
{
    if(a->addr[0] == b->addr[0] && a->addr[1] == b->addr[1] && a->addr[2] == b->addr[2] && a->addr[3] == b->addr[3])
        return true;
    return false;
}

struct lrtr_ipv6_addr lrtr_ipv6_get_bits(const struct lrtr_ipv6_addr *val, const uint8_t first_bit, const uint8_t quantity)
{
    assert(first_bit <= 127);
    assert(quantity <= 128);
    assert(first_bit + quantity <= 128);

    // if no bytes get extracted the result has to be 0
    struct lrtr_ipv6_addr result;
    memset(&result, 0, sizeof(result));

    uint8_t bits_left = quantity;

    if(first_bit <= 31) {
        const uint8_t q = quantity > 32 ? 32 : quantity;
        assert(bits_left >= q);
        bits_left -= q;
        result.addr[0] = lrtr_get_bits(val->addr[0], first_bit, q);
    }

    if((first_bit <= 63) && ((first_bit + quantity) > 32)) {
        const uint8_t fr = first_bit < 32 ? 0 : first_bit - 32;
        const uint8_t q = bits_left > 32 ? 32 : bits_left;
        assert(bits_left >= q);
        bits_left -= q;
        result.addr[1] = lrtr_get_bits(val->addr[1], fr, q);
    }

    if((first_bit <= 95) && ((first_bit + quantity) > 64)) {
        const uint8_t fr = first_bit < 64 ? 0 : first_bit - 64;
        const uint8_t q = bits_left > 32 ? 32 : bits_left;
        assert(bits_left >= q);
        bits_left -= q;
        result.addr[2] = lrtr_get_bits(val->addr[2], fr, q);
    }

    if((first_bit <= 127) && ((first_bit + quantity) > 96)) {
        const uint8_t fr = first_bit < 96 ? 0 : first_bit - 127;
        const uint8_t q = bits_left > 32 ? 32 : bits_left;
        assert(bits_left >= q);
        bits_left -= q;
        result.addr[3] = lrtr_get_bits(val->addr[3], fr, q);
    }
    return result;
}

/*
 * This function was copied from the bird routing daemon's ip_pton(..) function.
 */
int lrtr_ipv6_str_to_addr(const char *a, struct lrtr_ipv6_addr *ip)
{
    uint32_t *o = ip->addr;
    uint16_t words[8];
    int i, j, k, l, hfil;
    const char *start;

    if (a[0] == ':') {          /* Leading :: */
        if (a[1] != ':')
            return -1;
        a++;
    }
    hfil = -1;
    i = 0;
    while (*a) {
        if (*a == ':') {        /* :: */
            if (hfil >= 0)
                return -1;
            hfil = i;
            a++;
            continue;
        }
        j = 0;
        l = 0;
        start = a;
        for(;;) {
            if (*a >= '0' && *a <= '9')
                k = *a++ - '0';
            else if (*a >= 'A' && *a <= 'F')
                k = *a++ - 'A' + 10;
            else if (*a >= 'a' && *a <= 'f')
                k = *a++ - 'a' + 10;
            else
                break;
            j = (j << 4) + k;
            if (j >= 0x10000 || ++l > 4)
                return -1;
        }
        if (*a == ':' && a[1])
            a++;
        else if (*a == '.' && (i == 6 || (i < 6 && hfil >= 0))) {             /* Embedded IPv4 address */
            struct lrtr_ipv4_addr addr4;
            if (lrtr_ipv4_str_to_addr(start, &addr4) == -1)
                return -1;
            words[i++] = addr4.addr >> 16;
            words[i++] = addr4.addr;
            break;
        } else if (*a)
            return -1;
        if (i >= 8)
            return -1;
        words[i++] = j;
    }

    /* Replace :: with an appropriate quantity of zeros */
    if (hfil >= 0) {
        j = 8 - i;
        for(i=7; i-j >= hfil; i--)
            words[i] = words[i-j];
        for(; i>=hfil; i--)
            words[i] = 0;
    }

    /* Convert the address to lrtr_ip_addr format */
    for(i=0; i<4; i++)
        o[i] = (words[2*i] << 16) | words[2*i+1];
    return 0;
}

/*
 * This function was copied from the bird routing daemon's ip_ntop(..) function.
*/
int lrtr_ipv6_addr_to_str(const struct lrtr_ipv6_addr *ip_addr, char *b, const unsigned int len)
{
    if(len < INET6_ADDRSTRLEN)
        return -1;
    const uint32_t *a = ip_addr->addr;
    uint16_t words[8];
    int bestpos, bestlen, curpos, curlen, i;

    /* First of all, preprocess the address and find the longest run of zeros */
    bestlen = bestpos = curpos = curlen = 0;
    for(i = 0; i < 8; i++) {
        uint32_t x = a[i/2];
        words[i] = ((i % 2) ? x : (x >> 16)) & 0xffff;
        if (words[i])
            curlen = 0;
        else {
            if (!curlen)
                curpos = i;
            curlen++;
            if (curlen > bestlen) {
                bestpos = curpos;
                bestlen = curlen;
            }
        }
    }
    if (bestlen < 2)
        bestpos = -1;

    /* Is it an encapsulated IPv4 address? */
    if (!bestpos && ((bestlen == 5 && a[2] == 0xffff) || bestlen == 6))
        //if (!bestpos && ((bestlen == 5 && (a[2] == 0xffff)) || bestlen == 6))
    {
        uint32_t x = a[3];
        b += sprintf(b, "::%s%d.%d.%d.%d", a[2] ? "ffff:" : "", ((x >> 24) & 0xff), ((x >> 16) & 0xff), ((x >> 8) & 0xff), (x & 0xff));
        return 0;
    }

    /* Normal IPv6 formatting, compress the largest sequence of zeros */
    for(i = 0; i < 8; i++) {
        if (i == bestpos) {
            i += bestlen - 1;
            *b++ = ':';
            if (i == 7)
                *b++ = ':';
        } else {
            if (i)
                *b++ = ':';
            b += sprintf(b, "%x", words[i]);
        }
    }
    *b = '\0';
    return 0;
}

void lrtr_ipv6_addr_to_host_byte_order(const uint32_t *src, uint32_t *dest)
{
    for(int i = 0; i < 4; i++)
        dest[i] = ntohl(src[i]);
}