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make link structure, prepare ARP structure

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mykola2312 2024-12-18 10:44:52 +02:00
parent 9294334bf1
commit a37fa22b37
1 changed files with 67 additions and 16 deletions
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83
main.c
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@ -8,11 +8,10 @@
#include <netinet/in.h> #include <netinet/in.h>
#include <net/ethernet.h> #include <net/ethernet.h>
#include <linux/if_packet.h> #include <linux/if_packet.h>
#include <linux/if_arp.h>
typedef uint8_t mac_t[6]; #define MTU 1500
void parse_mac(const char* str, mac_t mac) { void parse_mac(const char* str, uint8_t* mac) {
char* s = strdup(str); char* s = strdup(str);
char* octet = strtok(s, ":"); char* octet = strtok(s, ":");
int i = 0; int i = 0;
@ -26,27 +25,79 @@ void parse_mac(const char* str, mac_t mac) {
free(s); free(s);
} }
int main(int argc, char** argv) { void print_mac(uint8_t* mac) {
// ifname hostMAC gatewayMAC targetMAC printf("%02x:%02x:%02x:%02x:%02x:%02x\n",
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
}
mac_t host, gateway, target; struct linkinterface {
parse_mac(argv[2], host); char* if_name;
parse_mac(argv[3], gateway); socklen_t if_len;
parse_mac(argv[4], target);
int raw = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); uint8_t host[ETH_ALEN];
if (raw < 0) { uint8_t gateway[ETH_ALEN];
perror("socket");
int fd; // raw socket
};
struct linkinterface* link_parse(const char* if_name, const char* host, const char* gateway) {
struct linkinterface* link = (struct linkinterface*)malloc(sizeof(struct linkinterface));
link->if_name = strdup(if_name);
link->if_len = strlen(link->if_name);
parse_mac(host, link->host);
parse_mac(gateway, link->gateway);
}
int link_open(struct linkinterface* link) {
link->fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (link->fd < 0) {
return 1; return 1;
} }
setsockopt(raw, SOL_SOCKET, SO_BINDTODEVICE, argv[1], strlen(argv[1])); setsockopt(link->fd, SOL_SOCKET, SO_BINDTODEVICE, link->if_name, link->if_name);
}
void link_free(struct linkinterface* link) {
close(link->fd);
free(link->if_name);
free(link);
}
typedef struct arp_packet_s {
struct ether_header ether;
uint16_t hrd; // Hardware address space (e.g., Ethernet, Packet Radio Net.)
uint16_t pro; // Protocol address space. For Ethernet hardware, this is from the set of type fields ether_typ$<protocol>.
uint8_t hln; // byte length of each hardware address
uint8_t pln; // byte length of each protocol address
uint16_t op; // opcode (ares_op$REQUEST | ares_op$REPLY)
uint8_t sha[ETH_ALEN]; // Hardware address of sender of this packet
uint8_t spa[4]; // Protocol address of sender of this packet
uint8_t tha[ETH_ALEN]; // Hardware address of sender of this packet
uint8_t tpa[4]; // Protocol address of sender of this packet
} __attribute__((packed)) arp_packet_t;
#define ARP_OP_REQUEST 0x01
#define ARP_OP_REPLY 0x02
int main(int argc, char** argv) {
// ifname hostMAC gatewayMAC targetMAC
struct linkinterface* link = link_parse(argv[1], argv[2], argv[3]);
uint8_t target[ETH_ALEN];
parse_mac(argv[4], target);
link_open(link);
// test receive // test receive
while (1) { while (1) {
uint8_t packet[1500]; uint8_t packet[MTU];
ssize_t rd = recv(raw, packet, 1500, 0); ssize_t rd = recv(link->fd, packet, MTU, 0);
printf("%lu\n", rd);
struct ether_header *ether = (struct ether_header *)&packet[0];
print_mac(ether->ether_shost);
} }
link_free(link);
return 0; return 0;
} }