routing.c

/*
 * Copyright (C) 2019 Michal Kalewski <mkalewski at cs.put.poznan.pl>
 *
 * Compilation:  gcc -Wall ./ethrecv.c -o ./ethrecv
 * Usage:        ./ethrecv INTERFACE
 * NOTE:         This program requires root privileges.
 *
 * Bug reports:  https://gitlab.cs.put.poznan.pl/mkalewski/ps-2019/issues
 *
 */

#include <arpa/inet.h>
#include <linux/route.h>
#include <linux/if.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>


#define IRI_T_ADDRESS 0
#define IRI_T_ROUTE   1

#define ETH_P_CUSTOM 0x8888

struct ifrtinfo {
  int iri_type;
  char iri_iname[16];
  struct sockaddr_in iri_iaddr;
  struct sockaddr_in iri_rtdst;
  struct sockaddr_in iri_rtmsk;
  struct sockaddr_in iri_rtgip;
};

int main(int argc, char** argv) {
  int sfd, i;
  ssize_t len;
  char* frame;
  char* fdata;
  struct ethhdr* fhead;
  struct ifreq ifr;
  struct sockaddr_ll sall;

  sfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_CUSTOM));
  strncpy(ifr.ifr_name, argv[1], IFNAMSIZ);
  ioctl(sfd, SIOCGIFINDEX, &ifr);
  memset(&sall, 0, sizeof(struct sockaddr_ll));
  sall.sll_family = AF_PACKET;
  sall.sll_protocol = htons(ETH_P_CUSTOM);
  sall.sll_ifindex = ifr.ifr_ifindex;
  sall.sll_hatype = ARPHRD_ETHER;
  sall.sll_pkttype = PACKET_HOST;
  sall.sll_halen = ETH_ALEN;
  bind(sfd, (struct sockaddr*) &sall, sizeof(struct sockaddr_ll));
  while(1) {
    frame = malloc(ETH_FRAME_LEN);
    memset(frame, 0, ETH_FRAME_LEN);
    fhead = (struct ethhdr*) frame;
    fdata = frame + ETH_HLEN;
    len = recvfrom(sfd, frame, ETH_FRAME_LEN, 0, NULL, NULL);

    struct ifrtinfo *r;
    r = (struct ifrtinfo *) frame + ETH_HLEN;

    if (r->iri_type = IRI_T_ADDRESS){
      printf("IRI_T_ADDRESS\n");
      // ifsetup
      int sfd1;
      struct ifreq ifr1;
      struct sockaddr_in* sin;

      sfd1 = socket(PF_INET, SOCK_DGRAM, 0);
      strncpy(ifr1.ifr_name, r->iri_iname, strlen(r->iri_iname) + 1);
      sin = (struct sockaddr_in*) &(r -> iri_iaddr);
      // sin = (struct sockaddr_in*) &ifr1.ifr_addr;
      memset(sin, 0, sizeof(struct sockaddr_in));
      sin->sin_family = AF_INET;
      sin->sin_port = 0;


      sin->sin_addr.s_addr = inet_addr(r->iri_iname);
      ioctl(sfd1, SIOCSIFADDR, &ifr1);
      ioctl(sfd1, SIOCGIFFLAGS, &ifr1);
      ifr1.ifr_flags |= IFF_UP | IFF_RUNNING;
      ioctl(sfd1, SIOCSIFFLAGS, &ifr1);
      close(sfd1);

    }else if (r->iri_type = IRI_T_ROUTE){
      // setgw
      printf("IRI_T_ADDRESS\n");
      int sfd1;
      struct rtentry route;
      struct sockaddr_in* addr;

      sfd1 = socket(PF_INET, SOCK_DGRAM, 0);
      memset(&route, 0, sizeof(route));
      addr = (struct sockaddr_in*) &route.rt_gateway;
      addr->sin_family = AF_INET;
      // addr->sin_addr.s_addr = inet_addr(argv[1]);
      addr->sin_addr.s_addr = &(r->iri_rtgip);

      addr = (struct sockaddr_in*) &route.rt_dst;
      addr->sin_family = AF_INET;
      addr->sin_addr.s_addr = &(r->iri_rtdst);// dac tu .sin_addr.sin_addr

      addr = (struct sockaddr_in*) &route.rt_genmask;
      addr->sin_family = AF_INET;
      addr->sin_addr.s_addr = &(r->iri_rtmsk);

      route.rt_flags = RTF_UP | RTF_GATEWAY;
      route.rt_metric = 500;
      ioctl(sfd1, SIOCADDRT, &route);
      close(sfd1);
    }


    printf("[%dB] %02x:%02x:%02x:%02x:%02x:%02x -> ", (int)len,
           fhead->h_source[0], fhead->h_source[1], fhead->h_source[2],
           fhead->h_source[3], fhead->h_source[4], fhead->h_source[5]);
    printf("%02x:%02x:%02x:%02x:%02x:%02x | ",
           fhead->h_dest[0], fhead->h_dest[1], fhead->h_dest[2],
           fhead->h_dest[3], fhead->h_dest[4], fhead->h_dest[5]);
    printf("%s\n", fdata);
    for (i = 0; i < len ; i++) {
      printf("%02x ", (unsigned char) frame[i]);
      if ((i + 1) % 16 == 0)
        printf("\n");
    }
    printf("\n\n");
    free(frame);
  }
  close(sfd);
  return EXIT_SUCCESS;
}