ether.c

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#include <core/system.h>
#include <core/string.h>
#include <net/byteorder.h>
#include <net/inet.h>

void ether_input(struct netif *netif, struct netbuf *nb)
{
    struct ether_hdr *eh = netbuf_pull(nb, sizeof(*eh));
 
    if (!eh) {
        netif->stats.rx_errors++;
        netbuf_free(nb);
        return;
    }
 
    switch (ntohs(eh->type)) {
        case ETHER_TYPE_ARP:
            arp_input(netif, nb);
            return;
        case ETHER_TYPE_IPV4:
            ipv4_input(netif, nb, eh->src);
            return;
    }
 
    netif->stats.rx_dropped++;
    netbuf_free(nb);
}

int ether_output(struct netif *netif, const uint8_t dst[6], uint16_t type, struct netbuf *nb)
{
    struct ether_hdr *eh = netbuf_push(nb, sizeof(*eh));
 
    memcpy(eh->dst, dst, 6);
    memcpy(eh->src, netif->mac, 6);
    eh->type = htons(type);
 
    int err = netif_output(netif, nb);
    netbuf_free(nb);
    return err;
}

uint16_t inet_checksum(const void *data, size_t len)
{
    const uint8_t *p = data;
    uint32_t sum = 0;
 
    for (; len > 1; len -= 2, p += 2)
        sum += (uint32_t) p[0] << 8 | p[1];
 
    if (len)
        sum += (uint32_t) p[0] << 8;
 
    while (sum >> 16)
        sum = (sum & 0xffff) + (sum >> 16);
 
    return htons(~sum & 0xffff);
}

uint16_t inet_checksum_pseudo(uint32_t src, uint32_t dst, uint8_t proto, const void *data, size_t len)
{
    struct {
        uint32_t src, dst;
        uint8_t zero, proto;
        uint16_t len;
    } __packed pseudo = {src, dst, 0, proto, htons(len)};
 
    const uint8_t *p = (const uint8_t *) &pseudo;
    uint32_t sum = 0;
 
    for (size_t i = 0; i < sizeof(pseudo); i += 2)
        sum += (uint32_t) p[i] << 8 | p[i + 1];
 
    for (p = data; len > 1; len -= 2, p += 2)
        sum += (uint32_t) p[0] << 8 | p[1];
 
    if (len)
        sum += (uint32_t) p[0] << 8;
 
    while (sum >> 16)
        sum = (sum & 0xffff) + (sum >> 16);
 
    return htons(~sum & 0xffff);
}