Linux下用C语言实现#获取机器IP/HOSTNAME


=Start=

缘由:

信息收集需要:IP/HOSTNAME

正文:

参考解答:

HOSTNAME的获取

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(void) {
    char hostname[1024];
    gethostname(hostname, 1024);
    puts(hostname);
    return EXIT_SUCCESS;
}

IP的获取

/*
 * Find local ip used as source ip in ip packets.
 * Read the /proc/net/route file
 */
#include <stdio.h> //printf
#include <string.h> //memset
#include <errno.h> //errno
#include <sys/socket.h>
#include <netdb.h>
#include <ifaddrs.h>
#include <stdlib.h>
#include <unistd.h>
int main ( int argc , char *argv[] )
{
    FILE *f;
    char line[100] , *p , *c;
    f = fopen("/proc/net/route" , "r");
    while(fgets(line , 100 , f))
    {
        p = strtok(line , " \t");
        c = strtok(NULL , " \t");
        if(p!=NULL && c!=NULL)
        {
            if(strcmp(c , "00000000") == 0)
            {
                printf("Default interface is : %s \n" , p);
                break;
            }
        }
    }
    //which family do we require , AF_INET or AF_INET6
    int fm = AF_INET;
    struct ifaddrs *ifaddr, *ifa;
    int family , s;
    char host[NI_MAXHOST];
    if (getifaddrs(&ifaddr) == -1)
    {
        perror("getifaddrs");
        exit(EXIT_FAILURE);
    }
    //Walk through linked list, maintaining head pointer so we can free list later
    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next)
    {
        if (ifa->ifa_addr == NULL)
        {
            continue;
        }
        family = ifa->ifa_addr->sa_family;
        if(strcmp( ifa->ifa_name , p) == 0)
        {
            if (family == fm)
            {
                s = getnameinfo( ifa->ifa_addr, (family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6) , host , NI_MAXHOST , NULL , 0 , NI_NUMERICHOST);
                if (s != 0)
                {
                    printf("getnameinfo() failed: %s\n", gai_strerror(s));
                    exit(EXIT_FAILURE);
                }
                printf("address: %s", host);
            }
            printf("\n");
        }
    }
    freeifaddrs(ifaddr);
    return 0;
}

&

#include <stdio.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/netdevice.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
int print_addresses(const int domain)
{
  int s;
  struct ifconf ifconf;
  struct ifreq ifr[50];
  int ifs;
  int i;
  s = socket(domain, SOCK_STREAM, 0);
  if (s < 0) {
    perror("socket");
    return 0;
  }
  ifconf.ifc_buf = (char *) ifr;
  ifconf.ifc_len = sizeof ifr;
  if (ioctl(s, SIOCGIFCONF, &ifconf) == -1) {
    perror("ioctl");
    return 0;
  }
  ifs = ifconf.ifc_len / sizeof(ifr[0]);
  printf("interfaces = %d:\n", ifs);
  for (i = 0; i < ifs; i++) {
    char ip[INET_ADDRSTRLEN];
    struct sockaddr_in *s_in = (struct sockaddr_in *) &ifr[i].ifr_addr;
    if (!inet_ntop(domain, &s_in->sin_addr, ip, sizeof(ip))) {
      perror("inet_ntop");
      return 0;
    }
    printf("%s - %s\n", ifr[i].ifr_name, ip);
  }
  close(s);
  return 1;
}
int main(int argc, char *argv[])
{
  int domains[] = { AF_INET, AF_INET6 };
  int i;
  for (i = 0; i < sizeof(domains) / sizeof(domains[0]); i++)
    if (!print_addresses(domains[i]))
      return 1;
  return 0;
}

=END=


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