mykola/arper
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

implement link_send and link_recv

Browse source
This commit is contained in:
mykola2312 2024-12-18 11:08:23 +02:00
parent a37fa22b37
commit c526033ad9
1 changed files with 37 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

37
main.c
View file

@ -80,6 +80,43 @@ typedef struct arp_packet_s {
#define ARP_OP_REQUEST 0x01
#define ARP_OP_REPLY 0x02
int link_send(struct linkinterface* link, uint16_t type, uint8_t* packet, size_t len) {
struct ether_header* ether = (struct ether_header*)packet;
memcpy(ether->ether_shost, link->host, ETH_ALEN);
memcpy(ether->ether_dhost, link->gateway, ETH_ALEN);
ether->ether_type = htons(type);
return send(link->fd, packet, len, 0);
}
int link_recv(struct linkinterface* link, uint16_t type, uint8_t* packet, size_t len) {
char buffer[MTU];
uint16_t want_type = htons(type);
do {
ssize_t rd = recv(link->fd, buffer, MTU, 0);
if (rd < 0) return -1;
struct ether_header* ether = (struct ether_header*)buffer;
// check received packet's source MAC
// if its someone else than gateway - skip
if (memcmp(ether->ether_shost, link->gateway, ETH_ALEN)) {
continue; // not our gateway
}
if (memcmp(ether->ether_dhost, link->host, ETH_ALEN)) {
continue; // not our host
}
if (ether->ether_type != want_type) {
continue; // not wanted type
}
// copy packet to recv buffer
memcpy(packet, buffer, rd);
return rd;
} while (1);
// TODO: timeout
}
int main(int argc, char** argv) {
// ifname hostMAC gatewayMAC targetMAC
struct linkinterface* link = link_parse(argv[1], argv[2], argv[3]);