Cách đặt địa chỉ IP từ chương trình C trong Linux?

#include <sys/ioctl.h>

#include <arpa/inet.h>

#include <net/if.h>

#include <string.h>

int main(int argc, const char *argv[]) {

    struct ifreq ifr;

    const char * name = “eth1”;

    int fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);

    strncpy(ifr.ifr_name, name, IFNAMSIZ);

    ifr.ifr_addr.sa_family = AF_INET;

    inet_pton(AF_INET, “10.12.0.1”, ifr.ifr_addr.sa_data + 2);

    ioctl(fd, SIOCSIFADDR, &ifr);

    inet_pton(AF_INET, “255.255.0.0”, ifr.ifr_addr.sa_data + 2);

    ioctl(fd, SIOCSIFNETMASK, &ifr);

    ioctl(fd, SIOCGIFFLAGS, &ifr);

    strncpy(ifr.ifr_name, name, IFNAMSIZ);

    ifr.ifr_flags |= (IFF_UP | IFF_RUNNING);

    ioctl(fd, SIOCSIFFLAGS, &ifr);

    return 0;

}

struct sockaddr_in* addr = (struct sockaddr_in*)&ifr.ifr_addr;

inet_pton(AF_INET, “10.12.0.1”, &addr->sin_addr);

set_ip(“eth0”, “192.168.181.128”, “192.168.181.1”);

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>           // close()

#include <string.h>           // strcpy, memset(), and memcpy()

#include <netdb.h>            // struct addrinfo

#include <sys/types.h>        // needed for socket(), uint8_t, uint16_t

#include <sys/socket.h>       // needed for socket()

#include <netinet/in.h>       // IPPROTO_RAW, INET_ADDRSTRLEN

#include <netinet/ip.h>       // IP_MAXPACKET (which is 65535)

#include <arpa/inet.h>        // inet_pton() and inet_ntop()

#include <sys/ioctl.h>        // macro ioctl is defined

#include <bits/ioctls.h>      // defines values for argument “request” of ioctl.

#include <net/if.h>           // struct ifreq

#include <linux/if_ether.h>   // ETH_P_ARP = 0x0806

#include <linux/if_packet.h>  // struct sockaddr_ll (see man 7 packet)

#include <net/ethernet.h>

#include <errno.h>            // errno, perror()

#include <netinet/in.h>

#include <net/route.h>    

 /**

    * Create socket function

    */

    int create_socket() {

      int sockfd = 0;

      sockfd = socket(AF_INET, SOCK_DGRAM, 0);

      if(sockfd == -1){

        fprintf(stderr, “Could not get socket.\n”);

        return -1;

      }

      return sockfd;

    }

    /**

    * Generic ioctrlcall to reduce code size

    */

    int generic_ioctrlcall(int sockfd, u_long *flags, struct ifreq *ifr) {

      if (ioctl(sockfd, (long unsigned int)flags, &ifr) < 0) {

        fprintf(stderr, “ioctl: %s\n”, (char *)flags);

        return -1;

      }

      return 1;

    }

    /**

    * Set route with metric 100

    */

    int set_route(int sockfd, char *gateway_addr,  struct sockaddr_in *addr) {

      struct rtentry route;

      int err = 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(gateway_addr);

      addr = (struct sockaddr_in*) &route.rt_dst;

      addr->sin_family = AF_INET;

      addr->sin_addr.s_addr = inet_addr(“0.0.0.0”);

      addr = (struct sockaddr_in*) &route.rt_genmask;

      addr->sin_family = AF_INET;

      addr->sin_addr.s_addr = inet_addr(“0.0.0.0”);

      route.rt_flags = RTF_UP | RTF_GATEWAY;

      route.rt_metric = 100;

      err = ioctl(sockfd, SIOCADDRT, &route);

      if ((err) < 0) {

        fprintf(stderr, “ioctl: %s\n”,  “mahdi MOAHMMADI Error”);

        return -1;

      }

      return 1;

    }

    /**

    * Set ip function

    */

    int set_ip(char *iface_name, char *ip_addr, char *gateway_addr)

    {

      if(!iface_name)

        return -1;

      struct ifreq ifr;

      struct sockaddr_in sin;

      int sockfd = create_socket();

      sin.sin_family = AF_INET;

      // Convert IP from numbers and dots to binary notation

      inet_aton(ip_addr,&sin.sin_addr.s_addr);

      /* get interface name */

      strncpy(ifr.ifr_name, iface_name, IFNAMSIZ);

      /* Read interface flags */

      generic_ioctrlcall(sockfd, (u_long *)”SIOCGIFFLAGS”, &ifr);

      /*

      * Expected in <net/if.h> according to

      * “UNIX Network Programming”.

      */

      #ifdef ifr_flags

      # define IRFFLAGS       ifr_flags

      #else   /* Present on kFreeBSD */

      # define IRFFLAGS       ifr_flagshigh

      #endif

      // If interface is down, bring it up

      if (ifr.IRFFLAGS | ~(IFF_UP)) {

        ifr.IRFFLAGS |= IFF_UP;

        generic_ioctrlcall(sockfd, (u_long *)”SIOCSIFFLAGS”, &ifr);

      }

      // Set route

      set_route(sockfd, gateway_addr    ,  &sin);

      memcpy(&ifr.ifr_addr, &sin, sizeof(struct sockaddr)); 

      // Set interface address

      if (ioctl(sockfd, SIOCSIFADDR, &ifr) < 0) {

        fprintf(stderr, “Cannot set IP address. “);

        perror(ifr.ifr_name);

        return -1;

      }             

      #undef IRFFLAGS 

      return 0;

    }