sendethframe.c

/**
 * @brief Sends an ethernet frame
 */

#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <linux/ip.h>

#define pexit(x)                                \
        do {                                    \
                perror(x);                      \
                exit(EXIT_FAILURE);             \
        } while (0)

static char buf[BUFSIZ];

void parse_mac(char *hwstr,  uint8_t mac[6])
{
        char *ptr;
        int i;

        for (i = 0, ptr = hwstr; i < 6; i++) {
                mac[i] = strtol(ptr, NULL, 16);
                ptr = strchr(ptr, ':');
                if (!ptr)
                        return;
                ptr++;
        }

}

void print_mac(uint8_t mac[6])
{
        int i;

        printf("MAC: ");
        for (i = 0; i < 6; i++)
                printf("%02X:", mac[i]);

        putchar('\n');
}

int main(int argc, char **argv)
{
        int sock;
        struct ifreq ifr;
        struct ether_header *eh = (struct ether_header *) buf;
        struct sockaddr_ll sll;
        int len = 0;
        int i = 0;
        int ifidx;
        int n;

        if (argc != 4) {
                fprintf(stderr, "Usage: %s SRCIF DSTHW DATA\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        if ((sock = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1)
                pexit("socket");

        memset(&ifr, '\0', sizeof(ifr));
        strncpy(ifr.ifr_name, argv[1], IFNAMSIZ - 1);
        if (ioctl(sock, SIOCGIFINDEX, &ifr) < 0)
                pexit("SIOCGIFINDEX");
        printf("Source index: %d\n", ifr.ifr_ifindex);
        ifidx = ifr.ifr_ifindex;

        if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0)
                pexit("SIOCGIFHWADDR");

        /* Set Destination and Source */
        memcpy(eh->ether_shost, ifr.ifr_hwaddr.sa_data, 6);
        printf("Source ");
        print_mac(eh->ether_shost);

        parse_mac(argv[2], eh->ether_dhost);
        printf("Destination ");
        print_mac(eh->ether_dhost);
        eh->ether_type = htons(ETH_P_ALL);

        len += sizeof(struct ether_header);

        strncpy(&buf[len], argv[3], strlen(argv[3]));
        len += strlen(argv[3]);

        printf("LENGHT: %d\n", len);

        memset(&sll, '\0', sizeof(sll));
        sll.sll_ifindex = ifidx;
        sll.sll_halen = ETH_ALEN;
        sll.sll_family = AF_PACKET;
        parse_mac(argv[2], (uint8_t *)&sll.sll_addr);

        len += sizeof(struct ether_header);

        if (sendto(sock, buf, ETH_ALEN, 0, (struct sockaddr *)&sll, sizeof(sll)) < 0)
                perror("send");

        if ((n = recvfrom(sock, buf, BUFSIZ, 0, NULL, NULL)) < 0)
                perror("recvfrom");

        printf("Received %d bytes from %02x:%02x:%02x:%02x:%02x:%02x\n",
               n,
               eh->ether_dhost[0],
               eh->ether_dhost[1],
               eh->ether_dhost[2],
               eh->ether_dhost[3],
               eh->ether_dhost[4],
               eh->ether_dhost[5]);

        return 0;
}