Comment puis-je connaître l'adresse IP des interfaces en C?

Question

Disons que je cours un programme appelé IpAddresses.c. Je veux que ce programme obtienne toutes les adresses IP de cet appareil selon chaque interface. Tout comme ifconfig. Comment puis je faire ça?

Je ne sais pas grand chose sur ioctl, mais j'ai lu que cela pourrait m'aider.

Answer 1

Utilisez simplement getifaddrs(). Voici un exemple:

#include <arpa/inet.h> 
#include <sys/socket.h> 
#include <ifaddrs.h> 
#include <stdio.h> 

int main() 
{ 
    struct ifaddrs *ifap, *ifa; 
    struct sockaddr_in *sa; 
    char *addr; 

    getifaddrs (&ifap); 
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 
     if (ifa->ifa_addr->sa_family==AF_INET) { 
      sa = (struct sockaddr_in *) ifa->ifa_addr; 
      addr = inet_ntoa(sa->sin_addr); 
      printf("Interface: %s\tAddress: %s\n", ifa->ifa_name, addr); 
     } 
    } 

    freeifaddrs(ifap); 
    return 0; 
} 

Et voici la sortie que je reçois sur ma machine:

Interface: lo Address: 127.0.0.1 
Interface: eth0 Address: 69.72.234.7 
Interface: eth0:1  Address: 10.207.9.3 

Answer 2

Vérifiez la (Windows spécifique) IP Helper API - heureusement, vous n'avez pas besoin ioctl pour cela sur Windows.

Answer 3

Vous pouvez essayer quelque chose comme ça:

struct ifreq ifr[MAX_INTERFACES]; 
struct ifconf ifc; 
memset(ifr, 0, sizeof(ifr)); 
ifc.ifc_len = sizeof(ifr); 
ifc.ifc_req = ifr; 

// Get the list of interfaces 
if (ioctl(sock, SIOCGIFCONF, &ifc) == -1) { 
    fprintf(stderr, "ioctl SIOCGIFCONF failed: %d", errno); 
} 

for (int i=0; i < ifc.ifc_len/sizeof(struct ifreq); ++i) { 
    if (ifr[i].ifr_addr.sa_family != AF_INET) { 
     continue; 
    } 

    // Maybe some more filtering based on SIOCGIFFLAGS 

    // Your code 
} 

Answer 4

Voir cette autre question Stack Overflow, Enumerating each IP address assigned to network interfaces.

En résumé, vous pouvez utiliser:

• ioctl(SIOCGIFCONF) -> ioctl traditionnelle
• getifaddrs() -> de BSDi, maintenant aussi sur Linux et BSD de.
• RTNETLINK (Linux)

Answer 5

Voici quelques exemple de code Linux qui pourraient vous aider.

#include <stdio.h> 
#include <net/if.h> 
#include <netinet/in.h> 
#include <sys/ioctl.h> 
#include <sys/types.h> 
#include <sys/socket.h> 

#define INT_TO_ADDR(_addr) \ 
(_addr & 0xFF), \ 
(_addr >> 8 & 0xFF), \ 
(_addr >> 16 & 0xFF), \ 
(_addr >> 24 & 0xFF) 

int main() 
{ 
    struct ifconf ifc; 
    struct ifreq ifr[10]; 
    int sd, ifc_num, addr, bcast, mask, network, i; 

    /* Create a socket so we can use ioctl on the file 
    * descriptor to retrieve the interface info. 
    */ 

    sd = socket(PF_INET, SOCK_DGRAM, 0); 
    if (sd > 0) 
    { 
     ifc.ifc_len = sizeof(ifr); 
     ifc.ifc_ifcu.ifcu_buf = (caddr_t)ifr; 

     if (ioctl(sd, SIOCGIFCONF, &ifc) == 0) 
     { 
      ifc_num = ifc.ifc_len/sizeof(struct ifreq); 
      printf("%d interfaces found\n", ifc_num); 

      for (i = 0; i < ifc_num; ++i) 
      { 
       if (ifr[i].ifr_addr.sa_family != AF_INET) 
       { 
        continue; 
       } 

       /* display the interface name */ 
       printf("%d) interface: %s\n", i+1, ifr[i].ifr_name); 

       /* Retrieve the IP address, broadcast address, and subnet mask. */ 
       if (ioctl(sd, SIOCGIFADDR, &ifr[i]) == 0) 
       { 
        addr = ((struct sockaddr_in *)(&ifr[i].ifr_addr))->sin_addr.s_addr; 
        printf("%d) address: %d.%d.%d.%d\n", i+1, INT_TO_ADDR(addr)); 
       } 
       if (ioctl(sd, SIOCGIFBRDADDR, &ifr[i]) == 0) 
       { 
        bcast = ((struct sockaddr_in *)(&ifr[i].ifr_broadaddr))->sin_addr.s_addr; 
        printf("%d) broadcast: %d.%d.%d.%d\n", i+1, INT_TO_ADDR(bcast)); 
       } 
       if (ioctl(sd, SIOCGIFNETMASK, &ifr[i]) == 0) 
       { 
        mask = ((struct sockaddr_in *)(&ifr[i].ifr_netmask))->sin_addr.s_addr; 
        printf("%d) netmask: %d.%d.%d.%d\n", i+1, INT_TO_ADDR(mask)); 
       }     

       /* Compute the current network value from the address and netmask. */ 
       network = addr & mask; 
       printf("%d) network: %d.%d.%d.%d\n", i+1, INT_TO_ADDR(network)); 
      }      
     } 

     close(sd); 
    } 

    return 0; 
} 

Answer 6

La solution à l'aide getifaddrs() est grande. Je suggérerais seulement un améliorer:

--- chrisaycock 
+++ normando 
@@ -11,7 +11,7 @@ 

    getifaddrs (&ifap); 
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 
-  if (ifa->ifa_addr->sa_family==AF_INET) { 
+  if (ifa->ifa_addr && ifa->ifa_addr->sa_family==AF_INET) { 
      sa = (struct sockaddr_in *) ifa->ifa_addr; 
      addr = inet_ntoa(sa->sin_addr); 
      printf("Interface: %s\tAddress: %s\n", ifa->ifa_name, addr); 

Juste parce que j'ai moi-même eu une erreur de segmentation.