1. Obtain the local IP address and mask /******************************** ************************************
* Function name: get_host_info
* Parameter Name: local_ip (out) IP
* Local_mask (out) mask
* Return value: 0 successfully
*-1 failed
* Function: Obtain the IP address and mask of the local machine.
**************************************** ****************************/
Int get_host_info (string & local_ip, string & local_mask)
{
Struct sockaddr_in * my_ip;
Struct sockaddr_in * ADDR;
Struct sockaddr_in myip;
My_ip = & myip;
Struct ifreq IFR;
Int sock;
If (sock = socket (af_inet, sock_dgram, 0) <0)
{
Return-1;
}
Strcpy (IFR. ifr_name, "eth0 ");
// Obtain the local IP Address
If (IOCTL (sock, siocgifaddr, & IFR) <0)
{
Return-1;
}
My_ip-> sin_addr = (struct sockaddr_in *) (& IFR. ifr_addr)-> sin_addr;
Local_ip = inet_ntoa (my_ip-> sin_addr );
// Obtain the local mask
If (IOCTL (sock, siocgifnetmask, & IFR) =-1 ){
Perror ("[-] IOCTL ");
Return-1;
}
ADDR = (struct sockaddr_in *) & (IFR. ifr_addr );
Local_mask = inet_ntoa (ADDR-> sin_addr );
Close (sock );
Return 0;
} 2. Retrieve the local gateway from the Internet. The error has been modified. # Define bufsize 8192 struct route_info {
U_int dstaddr;
U_int srcaddr;
U_int gateway;
Char ifname [if_namesize];
}; Int readnlsock (INT sockfd, char * bufptr, int seqnum, int PID)
{
Struct nlmsghdr * nlhdr;
Int readlen = 0, msglen = 0; do {
// Receives the kernel response
If (readlen = Recv (sockfd, bufptr, bufsize-msglen, 0) <0)
{
Perror ("Sock read :");
Return-1;
}
Nlhdr = (struct nlmsghdr *) bufptr; // check whether the header is valid
If (nlmsg_ OK (nlhdr, readlen) = 0) | (nlhdr-> nlmsg_type = nlmsg_error ))
{
Perror ("error in recieved packet ");
Return-1;
}
/* Check if the its last message */
If (nlhdr-> nlmsg_type = nlmsg_done)
{
Break;
}
Else
{
/* Else move the pointer to buffer appropriately */
Bufptr + = readlen;
Msglen + = readlen;
}
/* Check if its a multi part message */
If (nlhdr-> nlmsg_flags & nlm_f_multi) = 0)
{
/* Return if its not */
Break;
}
} While (nlhdr-> nlmsg_seq! = Seqnum) | (nlhdr-> nlmsg_pid! = PID ));
Return msglen;
} // Analyze the returned route information
Void parseroutes (struct nlmsghdr * nlhdr, struct route_info * rtinfo, char * gateway)
{
Struct rtmsg * rtmsg;
Struct rtattr * rtattr;
Int rtlen;
Char * tempbuf = NULL;
// 2007-12-10
Struct in_addr DST;
Struct in_addr gate;
Tempbuf = (char *) malloc (100 );
Rtmsg = (struct rtmsg *) nlmsg_data (nlhdr); // if the route is not for af_inet or does not belong to main routing table
// Then return.
If (rtmsg-> rtm_family! = Af_inet) | (rtmsg-> rtm_table! = Rt_table_main ))
Return;/* Get the rtattr field */
Rtattr = (struct rtattr *) rtm_rta (rtmsg );
Rtlen = rtm_payload (nlhdr );
For (; rta_ OK (rtattr, rtlen); rtattr = rta_next (rtattr, rtlen )){
Switch (rtattr-> rta_type ){
Case rta_oif:
If_indextoname (* (int *) rta_data (rtattr), rtinfo-> ifname );
Break;
Case rta_gateway:
Rtinfo-> gateway = * (u_int *) rta_data (rtattr );
Break;
Case rta_prefsrc:
Rtinfo-> srcaddr = * (u_int *) rta_data (rtattr );
Break;
Case rta_dst:
Rtinfo-> dstaddr = * (u_int *) rta_data (rtattr );
Break;
}
}
// 2007-12-10
DST. s_addr = rtinfo-> dstaddr;
If (strstr (char *) inet_ntoa (DST), "0.0.0.0 "))
{
Gate. s_addr = rtinfo-> gateway;
Sprintf (gateway, (char *) inet_ntoa (gate ));
}
Free (tempbuf );
Return;
}/************************************** ******************************
* Function name: get_gateway
* Parameter Name: Gateway (out) Gateway
* Return value: 0 successfully
*-1 failed
* Function: Obtain the gateway of the local machine.
**************************************** ****************************/
Int get_gateway (char * gateway)
{
Struct nlmsghdr * nlmsg;
Struct rtmsg * rtmsg;
Struct route_info * rtinfo;
Char msgbuf [bufsize];
Int sock, Len, msgseq = 0; // create a socket
If (sock = socket (pf_netlink, sock_dgram, netlink_route) <0)
{
Perror ("socket creation :");
Return-1;
}
/* Initialize the buffer */
Memset (msgbuf, 0, bufsize );
/* Point the header and the MSG structure pointers into the buffer */
Nlmsg = (struct nlmsghdr *) msgbuf;
Rtmsg = (struct rtmsg *) nlmsg_data (nlmsg );
/* Fill in the nlmsg header */
Nlmsg-> nlmsg_len = nlmsg_length (sizeof (struct rtmsg); // length of message.
Nlmsg-> nlmsg_type = rtm_getroute; // get the routes from kernel routing table.
Nlmsg-> nlmsg_flags = nlm_f_dump | nlm_f_request; // The message is a request for dump.
Nlmsg-> nlmsg_seq = msgseq ++; // sequence of the message packet.
Nlmsg-> nlmsg_pid = getpid (); // PID of process sending the request.
/* Send the request */
If (send (sock, nlmsg, nlmsg-> nlmsg_len, 0) <0 ){
Printf ("write to socket failed.../N ");
Return-1;
}
/* Read the response */
If (LEN = readnlsock (sock, msgbuf, msgseq, getpid () <0 ){
Printf ("read from socket failed.../N ");
Return-1;
}
/* Parse and print the response */
Rtinfo = (struct route_info *) malloc (sizeof (struct route_info); For (; nlmsg_ OK (nlmsg, Len); nlmsg = nlmsg_next (nlmsg, Len )){
Memset (rtinfo, 0, sizeof (struct route_info ));
Parseroutes (nlmsg, rtinfo, Gateway );
}
Free (rtinfo );
Close (sock );
Return 0;
} Include all these header files. I didn't know which ones are useless, but I added them with no errors: # include <stdio. h>
# Include <string. h>
# Include <unistd. h>
# Include <net/If. h>
# Include <sys/IOCTL. h>
# Include <sys/types. h>
# Include <sys/socket. h>
# Include <netinet/in. h>
# Include <netdb. h>
# Include <ARPA/inet. h>
# Include <net/if_arp.h>
# Include <string> # include <ASM/types. h>
# Include <netinet/ether. h> # include <sys/IOCTL. h>
# Include <Linux/Netlink. h>
# Include <Linux/rtnetlink. h>
# Include <stdlib. h> If the string type is used, add: Using namespace STD; the above functions are compiled and run. Here, I will give you a memo, and I will give you convenience! Reference address: http://blog.chinaunix.net/u1/56834/showart.php? Id = 442919 |
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