/*
 * Copyright (c) 2014 Chris Anderson
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "minip-internal.h"

/* XXX alternate implementation, merge */
uint16_t ones_sum16(uint32_t sum, const void *_buf, int len)
{
    const uint16_t *buf = _buf;

    while (len >= 2) {
        sum += *buf++;
        if(sum & 0x80000000)
            sum = (sum & 0xffff) + (sum >> 16);
        len -= 2;
    }

    if (len) {
        uint16_t temp = htons((*(uint8_t *)buf) << 8);
        sum += temp;
    }

    while (sum >> 16)
        sum = (sum & 0xffff) + (sum >> 16);

    return sum;
}

uint16_t rfc1701_chksum(const uint8_t *buf, size_t len)
{
    uint32_t total = 0;
    uint16_t chksum = 0;
    const uint16_t *p = (const uint16_t *) buf;

    // Length is in bytes
    for (size_t i = 0; i < len / 2; i++ ) {
        total += p[i];
    }

    chksum = (total & 0xFFFF) + (total >> 16);
    chksum = ~chksum;

    return chksum;
}

#if MINIP_USE_UDP_CHECKSUM
uint16_t rfc768_chksum(struct ipv4_hdr *ipv4, struct udp_hdr *udp)
{
    uint32_t total = 0;
    uint16_t chksum = 0;
    size_t len = ntohs(udp->len);
    uint16_t *p;

    p = (uint16_t *)ipv4->src_addr;
    total += htons(p[0]);
    total += htons(p[1]);

    p = (uint16_t *)ipv4->dst_addr;
    total += htons(p[0]);
    total += htons(p[1]);

    p = (const uint16_t *)udp->data;
    for (size_t i = 0; i < len / 2; i++ ) {
        total += p[i];
    }

    total += IP_PROTO_UDP;
    total += udp->len;
    total += udp->src_port;
    total += udp->dst_port;
    total += ipv4->len;

    chksum = (total & 0xFFFF) + (total >> 16);
    chksum = ~chksum;

    return chksum;
}
#endif

// vim: set ts=4 sw=4 expandtab: