Re: [developer] Raw ethernet packets

[Denis Kozadaev <denis@tambov.ru>]

witch% cat main.c 
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/ioctl.h>

#include <net/if.h>

#include <stdio.h>
#include <unistd.h>
#include <string.h>

int
main(void)
{
        int                     sock;
        struct sockaddr_ll      sll;
        struct lifreq           ifr;
        char                    buf[8192], dev[] = "dpi0";
        ssize_t                 result;

        sock = socket(AF_PACKET, SOCK_RAW, 0);
        if (sock < 0) {
                perror("socket");
                return (1);
        }

        strcpy(ifr.lifr_name, dev);
        result = ioctl(sock, SIOCGLIFINDEX, &ifr);
        sll.sll_family = AF_PACKET;
        sll.sll_ifindex = ifr.lifr_index;
        sll.sll_protocol = 0;
        result = bind(sock, (struct sockaddr *)&sll, sizeof(sll));

        for (;;) {
                result = recvfrom(sock, buf, sizeof(buf), 0, NULL, NULL);
                fprintf(stderr, "received %d bytes\n", (int)result);
        }

        close(sock);

        return (0);
}
/****************************/
This is my old code I played long time ago.
I hope this will help you...

On Friday 31 May 2024 11:54:26 Marcel Telka wrote:
> On Fri, May 31, 2024 at 10:43:03AM +0200, Marcel Telka wrote:
> > 1) socket()/bind()
> >
> >         int s = socket(AF_PACKET, SOCK_RAW, 0);
> >
> >         struct sockaddr_ll llp = {};
> >         llp.sll_family = AF_PACKET;
> >         llp.sll_protocol = 0x0800;
> >         llp.sll_ifindex = 5;    /* this is from ifconfig -a */
> >
> >         bind(s, (struct sockaddr *)&llp, sizeof (struct sockaddr_ll));
> >
> > The bind() call above failed.
>
> ... with ENOENT.  When I change the bind call to:
>
>         bind(s, (struct sockaddr *)&llp, sizeof (struct sockaddr));
>
> then it fails with EINVAL.