Linux obtiene información de la interfaz de red
La función que linux necesita usar para obtener información de la interfaz de red es ioctl (), estructura struct ifreq, struct ifconf
1.Función y prototipo de función ioctl ()
#include <sys/ioctl.h>
int ioctl(int d, int request, ...);
//参数
//int d：是一个文件描述符
//int request ：表示要请求的信息。如IP地址、网络掩码等
//......:可变参数，根据request而定
Los siguientes son los parámetros de solicitud de la solicitud ioctl y el tipo de datos al que debe apuntar la dirección arg:
2. estructura estructura ifreq
Esta estructura se define en include / net / if.h, se utiliza para configurar la dirección IP, activar la interfaz, configurar MTU y otra información de la interfaz
/* Interface request structure used for socket ioctl's. All interface
ioctl's must have parameter definitions which begin with ifr_name.
The remainder may be interface specific. */
struct ifreq
{
# define IFHWADDRLEN 6
# define IFNAMSIZ IF_NAMESIZE
union
{
char ifrn_name[IFNAMSIZ]; /* Interface name, e.g. "en0". */
} ifr_ifrn;
union
{
struct sockaddr ifru_addr;
struct sockaddr ifru_dstaddr;
struct sockaddr ifru_broadaddr;
struct sockaddr ifru_netmask;
struct sockaddr ifru_hwaddr;
short int ifru_flags;
int ifru_ivalue;
int ifru_mtu;
struct ifmap ifru_map;
char ifru_slave[IFNAMSIZ]; /* Just fits the size */
char ifru_newname[IFNAMSIZ];
__caddr_t ifru_data;
} ifr_ifru;
};
# define ifr_name ifr_ifrn.ifrn_name /* interface name */
# define ifr_hwaddr ifr_ifru.ifru_hwaddr /* MAC address */
# define ifr_addr ifr_ifru.ifru_addr /* address */
# define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-p lnk */
# define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */
# define ifr_netmask ifr_ifru.ifru_netmask /* interface net mask */
# define ifr_flags ifr_ifru.ifru_flags /* flags */
# define ifr_metric ifr_ifru.ifru_ivalue /* metric */
# define ifr_mtu ifr_ifru.ifru_mtu /* mtu */
# define ifr_map ifr_ifru.ifru_map /* device map */
# define ifr_slave ifr_ifru.ifru_slave /* slave device */
# define ifr_data ifr_ifru.ifru_data /* for use by interface */
# define ifr_ifindex ifr_ifru.ifru_ivalue /* interface index */
# define ifr_bandwidth ifr_ifru.ifru_ivalue /* link bandwidth */
# define ifr_qlen ifr_ifru.ifru_ivalue /* queue length */
# define ifr_newname ifr_ifru.ifru_newname /* New name */
# define _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)
# define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)
# define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)
3.struct ifconf
ifreq está incluido en la estructura ifconf. La estructura ifconf se usa generalmente para almacenar información sobre todas las interfaces.
/* Structure used in SIOCGIFCONF request. Used to retrieve interface
configuration for machine (useful for programs which must know all
networks accessible). */
struct ifconf
{
int ifc_len; /* Size of buffer. */
union
{
__caddr_t ifcu_buf;
struct ifreq *ifcu_req;
} ifc_ifcu;
};
# define ifc_buf ifc_ifcu.ifcu_buf /* Buffer address. */
# define ifc_req ifc_ifcu.ifcu_req /* Array of structures. */
# define _IOT_ifconf _IOT(_IOTS(struct ifconf),1,0,0,0,0) /* not right */
#endif /* Misc. */
El siguiente procedimiento es para obtener la dirección IP de la máquina.
#include <stdio.h>
#include <sys/socket.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <arpa/inet.h>
#ifndef IFNAMESZ
#define IFNAMESZ 16
#endif
int main(int argc, char *argv[])
{
if (argc != 2) {
printf("using %s <ETH_NAME>\n", argv[0]);
return 0;
}
int sock = 0;
struct sockaddr_in sin;
struct ifreq ifr;//用来保存接口的信息
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock == -1) {
perror("socket");
return 1;
}
memcpy(ifr.ifr_name, argv[1], IFNAMESZ);
ifr.ifr_name[IFNAMESZ - 1] = '\0';
if (ioctl(sock, SIOCGIFADDR, &ifr) == 0) {
//SIOCGIFADDR 获取接口地址
memcpy(&sin, &ifr.ifr_addr, sizeof(sin)); //将获得地址拷贝到 sockaddr_in 结构体中
printf("Ip: %s\n", inet_ntoa(sin.sin_addr));
}
if (ioctl(sock, SIOCGIFNETMASK, &ifr) == 0) {
memcpy(&sin, &ifr.ifr_netmask, sizeof(sin));
printf("netmask: %s\n", inet_ntoa(sin.sin_addr));
}
close(sock);
return 0;
}