ipv4.c

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#include "ipv4.h"
#include "ethernet.h"
#include "libk/serial.h"
#include <str.h>
#include "net/netdev.h"
#include "net/netutils.h"
#include "type.h"
 
static void fill_ip_header(struct ipv4_header* ip_hdr, uint16_t total_length,
               uint16_t id, uint16_t flags_fragment,
               uint8_t protocol, uint32_t src_ip, uint32_t dst_ip) {
    UNUSED(id);
    UNUSED(flags_fragment);
    ip_hdr->version_ihl = 0x45; // Version 4, IHL 5 (20 bytes)
    ip_hdr->tos = 0;
    ip_hdr->total_length = vxHtons(total_length);
 
    // sementara belum butuh fragmentasi
    ip_hdr->id = 0;
    ip_hdr->flags_fragment = 0;
    ip_hdr->ttl = 64;
    ip_hdr->protocol = protocol;
    // sementara hardcode
    ip_hdr->src_ip = src_ip;
    ip_hdr->dst_ip = dst_ip;
 
    ip_hdr->checksum = 0;
    ip_hdr->checksum = checksum16_adc((uint16_t*) (void*) ip_hdr,
                      sizeof(struct ipv4_header));
}
 
void ipv4_send(netdev_t* dev, struct netbuff* nb, uint32_t dst_ip,
           uint8_t protocol, uint8_t mac_dest[6]) {
 
    uint16_t mtu = dev->mtu;
    uint16_t max_ip_payload = mtu - sizeof(struct ipv4_header);
    uint16_t total_payload_len = nb->length;
    uint16_t sent = 0;
    uint16_t ip_id = get_next_ip_id(dev);
 
    // hardcode
    auto ip_addr = vxInetAddr("192.168.100.80");
    // serial2_printf("ipv4\n");
 
    if (total_payload_len <= max_ip_payload) {
        struct ipv4_header* ip_hdr = (struct ipv4_header*) netbuff_push(
            nb, sizeof(struct ipv4_header));
        fill_ip_header(ip_hdr,
                   total_payload_len + sizeof(struct ipv4_header),
                   ip_id, 0, protocol, ip_addr, dst_ip);
        ethernet_send_frame(dev, nb, vxHtons(ETHER_TYPE_IP), mac_dest);
        return;
    }
 
    while (sent < total_payload_len) {
        uint16_t chunk_size =
            (total_payload_len - sent > max_ip_payload)
                ? max_ip_payload
                : (total_payload_len - sent);
 
        // Buat netbuff baru untuk fragmen ini
        auto frag_nb = create_netbuff();
        uint8_t* dest = netbuff_put(frag_nb, chunk_size);
 
        // Copy potongan data dari netbuff utama ke netbuff fragmen
        memcopy(dest, nb->data + sent, chunk_size);
 
        // Tempel Header IP
        struct ipv4_header* ip_hdr = (struct ipv4_header*) netbuff_push(
            frag_nb, sizeof(struct ipv4_header));
 
        // Hitung Flags & Offset
        uint16_t offset = sent / 8;
        uint16_t flags_offset = offset & 0x1FFF;
        if (sent + chunk_size < total_payload_len) {
            flags_offset |= 0x2000; // More Fragments (MF) = 1
        }
 
        fill_ip_header(ip_hdr, frag_nb->length, ip_id, flags_offset,
                   protocol, ip_addr, dst_ip);
 
        ethernet_send_frame(dev, frag_nb, vxHtons(ETHER_TYPE_IP),
                    mac_dest);
 
        sent += chunk_size;
        free_netbuff(frag_nb); // Hapus fragmen setelah dikirim
    }
}