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#include <assert.h>
#include <drivers/rtl8139.h>
#include <network/arp.h>
#include <network/bytes.h>
#include <network/ethernet.h>
#include <stdio.h>
#include <string.h>
struct ARP_DATA {
u16 htype; // Hardware type
u16 ptype; // Protocol type
u8 hlen; // Hardware address length (Ethernet = 6)
u8 plen; // Protocol address length (IPv4 = 4)
u16 opcode; // ARP Operation Code
u8 srchw[6]; // Source hardware address - hlen bytes (see above)
u8 srcpr[4]; // Source protocol address - plen bytes (see above).
// If IPv4 can just be a "u32" type.
u8 dsthw[6]; // Destination hardware address - hlen bytes (see above)
u8 dstpr[4]; // Destination protocol address - plen bytes (see
// above). If IPv4 can just be a "u32" type.
};
struct ARP_TABLE_ENTRY {
u8 is_used;
u8 mac[6];
u8 ip[4];
};
struct ARP_TABLE_ENTRY arp_table[10] = {0};
// FIXME: This is hardcoded, don't do this.
u8 ip_address[4] = {10, 0, 2, 15};
struct ARP_TABLE_ENTRY *find_arp_entry_to_use(void) {
// This does not need to find a "free" entry as a ARP table is
// just a cache, it just has to pick a entry efficently.
for (int i = 0; i < 10; i++) {
if (!arp_table[i].is_used) {
return &arp_table[i];
}
}
return &arp_table[0];
}
void print_mac(const char *str, u8 *mac) {
kprintf("%s: ", str);
for (int i = 0; i < 6; i++) {
kprintf("%x", mac[i]);
if (5 != i) {
kprintf(":");
}
}
kprintf("\n");
}
void print_ip(const char *str, const u8 *ip) {
kprintf("%s: ", str);
for (int i = 0; i < 4; i++) {
kprintf("%d", ip[i]);
if (3 != i) {
kprintf(".");
}
}
kprintf("\n");
}
void send_arp_request(const u8 ip[4]) {
struct ARP_DATA data;
data.htype = htons(1);
data.ptype = htons(0x0800);
data.hlen = 6;
data.plen = 4;
data.opcode = htons(0x0001);
get_mac_address(data.srchw);
memcpy(data.srcpr, ip_address, sizeof(u8[4]));
memset(data.dsthw, 0, sizeof(u8[6]));
memcpy(data.dstpr, ip, sizeof(u8[4]));
u8 broadcast[6];
memset(broadcast, 0xFF, sizeof(broadcast));
send_ethernet_packet(broadcast, 0x0806, (u8 *)&data, sizeof(data));
}
int get_mac_from_ip(const u8 ip[4], u8 mac[6]) {
for (int i = 0; i < 10; i++) {
if (0 != memcmp(arp_table[i].ip, ip, sizeof(u8[4]))) {
continue;
}
memcpy(mac, arp_table[i].mac, sizeof(u8[6]));
return 1;
}
klog("ARP cache miss", LOG_NOTE);
send_arp_request(ip);
// TODO: Maybe wait a bit?
for (int i = 0; i < 10; i++) {
if (0 != memcmp(arp_table[i].ip, ip, sizeof(u8[4]))) {
continue;
}
memcpy(mac, arp_table[i].mac, sizeof(u8[6]));
return 1;
}
return 0;
}
void handle_arp(const u8 *payload) {
struct ARP_DATA *data = (struct ARP_DATA *)payload;
// Assert that communication is over ethernet
assert(1 == ntohs(data->htype));
// Assert that request uses IP
assert(0x0800 == ntohs(data->ptype));
assert(6 == data->hlen);
assert(4 == data->plen);
// Assert it is a request
if (0x0001 /*arp_request*/ == ntohs(data->opcode)) {
struct ARP_TABLE_ENTRY *entry = find_arp_entry_to_use();
entry->is_used = 1;
memcpy(entry->mac, data->srchw, sizeof(uint8_t[6]));
memcpy(entry->ip, data->srcpr, sizeof(uint8_t[4]));
assert(0 == memcmp(data->dstpr, ip_address, sizeof(uint8_t[4])));
// Now we have to construct a ARP response
struct ARP_DATA response;
response.htype = htons(1);
response.ptype = htons(0x0800);
response.opcode = htons(0x00002);
response.hlen = 6;
response.plen = 4;
get_mac_address(response.srchw);
memcpy(response.srcpr, ip_address, sizeof(u8[4]));
memcpy(response.dsthw, data->srchw, sizeof(u8[6]));
memcpy(response.dstpr, data->srcpr, sizeof(u8[4]));
send_ethernet_packet(data->srchw, 0x0806, (u8 *)&response,
sizeof(response));
} else if (0x0002 /*arp_response*/ == ntohs(data->opcode)) {
// Find a entry to fill
struct ARP_TABLE_ENTRY *entry = find_arp_entry_to_use();
entry->is_used = 1;
memcpy(entry->mac, data->srchw, sizeof(u8[6]));
memcpy(entry->ip, data->srcpr, sizeof(u8[4]));
} else {
kprintf("GOT A ARP REQEUST WITH TYPE: %x\n", ntohs(data->opcode));
assert(0);
}
}
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