Thread: Cannot get interface flags: Invalid argument

I am not able to connect flag interface using my program function. I need help. Please help me to solve this problem.

Code:

#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <stdlib.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <malloc.h>
#include <netinet/in_systm.h>
#include <net/if_arp.h>
#include <net/if.h>
#include <netinet/udp.h>
#define __FAVOR_BSD
#include <netinet/tcp.h> 
//#include <netinet/udp.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <linux/if_ether.h>
#include <syslog.h>

#define PKTLEN 96	/* Should be enough for what we want */
#ifndef IP_MF
#define IP_MF	0x2000
#endif

/***** WATCH LEVELS ******/

#define MYSELFONLY	1
#define MYSUBNET	2
#define HUMANITARIAN	3

/***** REPORT LEVELS *****/

#define REPORTALL	1
#define REPORTDOS	2
#define REPORTSCAN	3

struct floodinfo {
    u_short sport;
    struct floodinfo *next;
};

struct addrlist {
    u_long saddr;
    int cnt;
    int wwwcnt;
    struct addrlist *next;
};

struct atk {
    u_long saddr;
    u_char eaddr[ETH_ALEN];
    time_t atktime;
};

struct pktin {
    u_long saddr;
    u_short sport;
    u_short dport;
    time_t timein;
    u_char eaddr[ETH_ALEN];
    struct floodinfo *fi;
    struct pktin *next;
};

struct scaninfo {
    u_long addr;
    struct atk teardrop;
    struct atk land;
    struct atk icmpfrag;
    struct pktin *tcpin;
    struct pktin *udpin;
    struct scaninfo *next;
    u_long icmpcnt;
} ;

struct scaninfo *Gsilist = NULL, *Gsi;

u_long Gmaddr;
time_t Gtimer = 10, Gtimein;
int Gportlimit = 7;
int Gsynflood = 8;
int Gwebcount = 40;
int Gicmplimit = 5;
int Gwatchlevel = MYSELFONLY;
int Greportlevel = REPORTALL;
char *Gprogramname, *Gdevice = "eth0";

/******** IP packet info ********/

u_long Gsaddr, Gdaddr;
int Giplen, Gisfrag, Gid;

/****** Externals *************/
int SIOCGIFFLAGS;
int SIOCSIFFLAGS;


extern int errno;
extern char *optarg;
extern int optind, opterr;

void do_tcp(), do_udp(), do_icmp(), print_info(), process_packet();
void addtcp(), addudp(), clear_pktin(), buildnet();
void doargs(), usage(), addfloodinfo(), rmfloodinfo();
struct scaninfo *doicare(), *addtarget();
char *anetaddr(), *ether_ntoa();
u_char *readdevice();
int SIOCGIFFLAGS;
int SIOCSIFFLAGS;

main(argc, argv)
int argc;
char *argv[];
{
    int pktlen = 0, i, netfd;
    u_char *pkt;
    char hostname[32];
    struct hostent *hp;
    time_t t;

    doargs(argc, argv);
    openlog("WATCHER", 0, LOG_DAEMON);
    if(gethostname(hostname, sizeof(hostname)) < 0)
    {
	perror("gethostname");
	exit(-1);
    }
    if((hp = gethostbyname(hostname)) == NULL)
    {
	fprintf(stderr, "Cannot find own address\n");
	exit(-1);
    }
    memcpy((char *)&Gmaddr, hp->h_addr, hp->h_length);
    buildnet();
    if((netfd = initdevice(O_RDWR, 0)) < 0)
	exit(-1);

    /* Now read packets forever and process them. */

    t = time((time_t *)0);
    while(pkt = readdevice(netfd, &pktlen))
    {
	process_packet(pkt, pktlen);
	if(time((time_t *)0) - t > Gtimer)
	{
	    /* Times up.  Print what we found and clean out old stuff. */

	    for(Gsi = Gsilist, i = 0; Gsi; Gsi = Gsi->next, i++)
	    {
                clear_pktin(Gsi);
	        print_info();
		Gsi->icmpcnt = 0;
	    }
	    t = time((time_t *)0);
	}
    }
}

/************************************************************************
Function:  initdevice

Description: Set up the network device so we can read it.

**************************************************************************/
initdevice(int fd_flags, u_long dflags)

{
    struct ifreq ifr;
    int fd, flags = 0;

    if((fd = socket(PF_INET, SOCK_PACKET, htons(0x0003))) < 0)
    {
	perror("Cannot open device socket");
	exit(-1);
    }

    /* Get the existing interface flags */

    strcpy(ifr.ifr_name, Gdevice);
    if(ioctl(fd, SIOCGIFFLAGS, &ifr) < 0)
    {
	perror("Cannot get interface flags");
	exit(-1);
    }

    ifr.ifr_flags |= IFF_PROMISC;
    if(ioctl(fd, SIOCSIFFLAGS,  &ifr) < 0)
    {
	perror("Cannot set interface flags");
	exit(-1);
    }
    
    return(fd);
}